diff options
Diffstat (limited to 'kernel/fs/notify')
24 files changed, 4499 insertions, 0 deletions
diff --git a/kernel/fs/notify/Kconfig b/kernel/fs/notify/Kconfig new file mode 100644 index 000000000..2a24249b3 --- /dev/null +++ b/kernel/fs/notify/Kconfig @@ -0,0 +1,7 @@ +config FSNOTIFY + def_bool n + select SRCU + +source "fs/notify/dnotify/Kconfig" +source "fs/notify/inotify/Kconfig" +source "fs/notify/fanotify/Kconfig" diff --git a/kernel/fs/notify/Makefile b/kernel/fs/notify/Makefile new file mode 100644 index 000000000..96d3420d0 --- /dev/null +++ b/kernel/fs/notify/Makefile @@ -0,0 +1,6 @@ +obj-$(CONFIG_FSNOTIFY) += fsnotify.o notification.o group.o inode_mark.o \ + mark.o vfsmount_mark.o fdinfo.o + +obj-y += dnotify/ +obj-y += inotify/ +obj-y += fanotify/ diff --git a/kernel/fs/notify/dnotify/Kconfig b/kernel/fs/notify/dnotify/Kconfig new file mode 100644 index 000000000..f9c1ca139 --- /dev/null +++ b/kernel/fs/notify/dnotify/Kconfig @@ -0,0 +1,11 @@ +config DNOTIFY + bool "Dnotify support" + select FSNOTIFY + default y + help + Dnotify is a directory-based per-fd file change notification system + that uses signals to communicate events to user-space. There exist + superior alternatives, but some applications may still rely on + dnotify. + + If unsure, say Y. diff --git a/kernel/fs/notify/dnotify/Makefile b/kernel/fs/notify/dnotify/Makefile new file mode 100644 index 000000000..f145251dc --- /dev/null +++ b/kernel/fs/notify/dnotify/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_DNOTIFY) += dnotify.o diff --git a/kernel/fs/notify/dnotify/dnotify.c b/kernel/fs/notify/dnotify/dnotify.c new file mode 100644 index 000000000..44523f4a6 --- /dev/null +++ b/kernel/fs/notify/dnotify/dnotify.c @@ -0,0 +1,388 @@ +/* + * Directory notifications for Linux. + * + * Copyright (C) 2000,2001,2002 Stephen Rothwell + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * dnotify was largly rewritten to use the new fsnotify infrastructure + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#include <linux/fs.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/dnotify.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/fdtable.h> +#include <linux/fsnotify_backend.h> + +int dir_notify_enable __read_mostly = 1; + +static struct kmem_cache *dnotify_struct_cache __read_mostly; +static struct kmem_cache *dnotify_mark_cache __read_mostly; +static struct fsnotify_group *dnotify_group __read_mostly; + +/* + * dnotify will attach one of these to each inode (i_fsnotify_marks) which + * is being watched by dnotify. If multiple userspace applications are watching + * the same directory with dnotify their information is chained in dn + */ +struct dnotify_mark { + struct fsnotify_mark fsn_mark; + struct dnotify_struct *dn; +}; + +/* + * When a process starts or stops watching an inode the set of events which + * dnotify cares about for that inode may change. This function runs the + * list of everything receiving dnotify events about this directory and calculates + * the set of all those events. After it updates what dnotify is interested in + * it calls the fsnotify function so it can update the set of all events relevant + * to this inode. + */ +static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) +{ + __u32 new_mask, old_mask; + struct dnotify_struct *dn; + struct dnotify_mark *dn_mark = container_of(fsn_mark, + struct dnotify_mark, + fsn_mark); + + assert_spin_locked(&fsn_mark->lock); + + old_mask = fsn_mark->mask; + new_mask = 0; + for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next) + new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); + fsnotify_set_mark_mask_locked(fsn_mark, new_mask); + + if (old_mask == new_mask) + return; + + if (fsn_mark->inode) + fsnotify_recalc_inode_mask(fsn_mark->inode); +} + +/* + * Mains fsnotify call where events are delivered to dnotify. + * Find the dnotify mark on the relevant inode, run the list of dnotify structs + * on that mark and determine which of them has expressed interest in receiving + * events of this type. When found send the correct process and signal and + * destroy the dnotify struct if it was not registered to receive multiple + * events. + */ +static int dnotify_handle_event(struct fsnotify_group *group, + struct inode *inode, + struct fsnotify_mark *inode_mark, + struct fsnotify_mark *vfsmount_mark, + u32 mask, void *data, int data_type, + const unsigned char *file_name, u32 cookie) +{ + struct dnotify_mark *dn_mark; + struct dnotify_struct *dn; + struct dnotify_struct **prev; + struct fown_struct *fown; + __u32 test_mask = mask & ~FS_EVENT_ON_CHILD; + + /* not a dir, dnotify doesn't care */ + if (!S_ISDIR(inode->i_mode)) + return 0; + + BUG_ON(vfsmount_mark); + + dn_mark = container_of(inode_mark, struct dnotify_mark, fsn_mark); + + spin_lock(&inode_mark->lock); + prev = &dn_mark->dn; + while ((dn = *prev) != NULL) { + if ((dn->dn_mask & test_mask) == 0) { + prev = &dn->dn_next; + continue; + } + fown = &dn->dn_filp->f_owner; + send_sigio(fown, dn->dn_fd, POLL_MSG); + if (dn->dn_mask & FS_DN_MULTISHOT) + prev = &dn->dn_next; + else { + *prev = dn->dn_next; + kmem_cache_free(dnotify_struct_cache, dn); + dnotify_recalc_inode_mask(inode_mark); + } + } + + spin_unlock(&inode_mark->lock); + + return 0; +} + +static void dnotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + struct dnotify_mark *dn_mark = container_of(fsn_mark, + struct dnotify_mark, + fsn_mark); + + BUG_ON(dn_mark->dn); + + kmem_cache_free(dnotify_mark_cache, dn_mark); +} + +static struct fsnotify_ops dnotify_fsnotify_ops = { + .handle_event = dnotify_handle_event, +}; + +/* + * Called every time a file is closed. Looks first for a dnotify mark on the + * inode. If one is found run all of the ->dn structures attached to that + * mark for one relevant to this process closing the file and remove that + * dnotify_struct. If that was the last dnotify_struct also remove the + * fsnotify_mark. + */ +void dnotify_flush(struct file *filp, fl_owner_t id) +{ + struct fsnotify_mark *fsn_mark; + struct dnotify_mark *dn_mark; + struct dnotify_struct *dn; + struct dnotify_struct **prev; + struct inode *inode; + + inode = file_inode(filp); + if (!S_ISDIR(inode->i_mode)) + return; + + fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode); + if (!fsn_mark) + return; + dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); + + mutex_lock(&dnotify_group->mark_mutex); + + spin_lock(&fsn_mark->lock); + prev = &dn_mark->dn; + while ((dn = *prev) != NULL) { + if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { + *prev = dn->dn_next; + kmem_cache_free(dnotify_struct_cache, dn); + dnotify_recalc_inode_mask(fsn_mark); + break; + } + prev = &dn->dn_next; + } + + spin_unlock(&fsn_mark->lock); + + /* nothing else could have found us thanks to the dnotify_groups + mark_mutex */ + if (dn_mark->dn == NULL) + fsnotify_destroy_mark_locked(fsn_mark, dnotify_group); + + mutex_unlock(&dnotify_group->mark_mutex); + + fsnotify_put_mark(fsn_mark); +} + +/* this conversion is done only at watch creation */ +static __u32 convert_arg(unsigned long arg) +{ + __u32 new_mask = FS_EVENT_ON_CHILD; + + if (arg & DN_MULTISHOT) + new_mask |= FS_DN_MULTISHOT; + if (arg & DN_DELETE) + new_mask |= (FS_DELETE | FS_MOVED_FROM); + if (arg & DN_MODIFY) + new_mask |= FS_MODIFY; + if (arg & DN_ACCESS) + new_mask |= FS_ACCESS; + if (arg & DN_ATTRIB) + new_mask |= FS_ATTRIB; + if (arg & DN_RENAME) + new_mask |= FS_DN_RENAME; + if (arg & DN_CREATE) + new_mask |= (FS_CREATE | FS_MOVED_TO); + + return new_mask; +} + +/* + * If multiple processes watch the same inode with dnotify there is only one + * dnotify mark in inode->i_fsnotify_marks but we chain a dnotify_struct + * onto that mark. This function either attaches the new dnotify_struct onto + * that list, or it |= the mask onto an existing dnofiy_struct. + */ +static int attach_dn(struct dnotify_struct *dn, struct dnotify_mark *dn_mark, + fl_owner_t id, int fd, struct file *filp, __u32 mask) +{ + struct dnotify_struct *odn; + + odn = dn_mark->dn; + while (odn != NULL) { + /* adding more events to existing dnofiy_struct? */ + if ((odn->dn_owner == id) && (odn->dn_filp == filp)) { + odn->dn_fd = fd; + odn->dn_mask |= mask; + return -EEXIST; + } + odn = odn->dn_next; + } + + dn->dn_mask = mask; + dn->dn_fd = fd; + dn->dn_filp = filp; + dn->dn_owner = id; + dn->dn_next = dn_mark->dn; + dn_mark->dn = dn; + + return 0; +} + +/* + * When a process calls fcntl to attach a dnotify watch to a directory it ends + * up here. Allocate both a mark for fsnotify to add and a dnotify_struct to be + * attached to the fsnotify_mark. + */ +int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) +{ + struct dnotify_mark *new_dn_mark, *dn_mark; + struct fsnotify_mark *new_fsn_mark, *fsn_mark; + struct dnotify_struct *dn; + struct inode *inode; + fl_owner_t id = current->files; + struct file *f; + int destroy = 0, error = 0; + __u32 mask; + + /* we use these to tell if we need to kfree */ + new_fsn_mark = NULL; + dn = NULL; + + if (!dir_notify_enable) { + error = -EINVAL; + goto out_err; + } + + /* a 0 mask means we are explicitly removing the watch */ + if ((arg & ~DN_MULTISHOT) == 0) { + dnotify_flush(filp, id); + error = 0; + goto out_err; + } + + /* dnotify only works on directories */ + inode = file_inode(filp); + if (!S_ISDIR(inode->i_mode)) { + error = -ENOTDIR; + goto out_err; + } + + /* expect most fcntl to add new rather than augment old */ + dn = kmem_cache_alloc(dnotify_struct_cache, GFP_KERNEL); + if (!dn) { + error = -ENOMEM; + goto out_err; + } + + /* new fsnotify mark, we expect most fcntl calls to add a new mark */ + new_dn_mark = kmem_cache_alloc(dnotify_mark_cache, GFP_KERNEL); + if (!new_dn_mark) { + error = -ENOMEM; + goto out_err; + } + + /* convert the userspace DN_* "arg" to the internal FS_* defines in fsnotify */ + mask = convert_arg(arg); + + /* set up the new_fsn_mark and new_dn_mark */ + new_fsn_mark = &new_dn_mark->fsn_mark; + fsnotify_init_mark(new_fsn_mark, dnotify_free_mark); + new_fsn_mark->mask = mask; + new_dn_mark->dn = NULL; + + /* this is needed to prevent the fcntl/close race described below */ + mutex_lock(&dnotify_group->mark_mutex); + + /* add the new_fsn_mark or find an old one. */ + fsn_mark = fsnotify_find_inode_mark(dnotify_group, inode); + if (fsn_mark) { + dn_mark = container_of(fsn_mark, struct dnotify_mark, fsn_mark); + spin_lock(&fsn_mark->lock); + } else { + fsnotify_add_mark_locked(new_fsn_mark, dnotify_group, inode, + NULL, 0); + spin_lock(&new_fsn_mark->lock); + fsn_mark = new_fsn_mark; + dn_mark = new_dn_mark; + /* we used new_fsn_mark, so don't free it */ + new_fsn_mark = NULL; + } + + rcu_read_lock(); + f = fcheck(fd); + rcu_read_unlock(); + + /* if (f != filp) means that we lost a race and another task/thread + * actually closed the fd we are still playing with before we grabbed + * the dnotify_groups mark_mutex and fsn_mark->lock. Since closing the + * fd is the only time we clean up the marks we need to get our mark + * off the list. */ + if (f != filp) { + /* if we added ourselves, shoot ourselves, it's possible that + * the flush actually did shoot this fsn_mark. That's fine too + * since multiple calls to destroy_mark is perfectly safe, if + * we found a dn_mark already attached to the inode, just sod + * off silently as the flush at close time dealt with it. + */ + if (dn_mark == new_dn_mark) + destroy = 1; + goto out; + } + + __f_setown(filp, task_pid(current), PIDTYPE_PID, 0); + + error = attach_dn(dn, dn_mark, id, fd, filp, mask); + /* !error means that we attached the dn to the dn_mark, so don't free it */ + if (!error) + dn = NULL; + /* -EEXIST means that we didn't add this new dn and used an old one. + * that isn't an error (and the unused dn should be freed) */ + else if (error == -EEXIST) + error = 0; + + dnotify_recalc_inode_mask(fsn_mark); +out: + spin_unlock(&fsn_mark->lock); + + if (destroy) + fsnotify_destroy_mark_locked(fsn_mark, dnotify_group); + + mutex_unlock(&dnotify_group->mark_mutex); + fsnotify_put_mark(fsn_mark); +out_err: + if (new_fsn_mark) + fsnotify_put_mark(new_fsn_mark); + if (dn) + kmem_cache_free(dnotify_struct_cache, dn); + return error; +} + +static int __init dnotify_init(void) +{ + dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC); + dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC); + + dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops); + if (IS_ERR(dnotify_group)) + panic("unable to allocate fsnotify group for dnotify\n"); + return 0; +} + +module_init(dnotify_init) diff --git a/kernel/fs/notify/fanotify/Kconfig b/kernel/fs/notify/fanotify/Kconfig new file mode 100644 index 000000000..e5f911bd8 --- /dev/null +++ b/kernel/fs/notify/fanotify/Kconfig @@ -0,0 +1,26 @@ +config FANOTIFY + bool "Filesystem wide access notification" + select FSNOTIFY + select ANON_INODES + default n + ---help--- + Say Y here to enable fanotify support. fanotify is a file access + notification system which differs from inotify in that it sends + an open file descriptor to the userspace listener along with + the event. + + If unsure, say Y. + +config FANOTIFY_ACCESS_PERMISSIONS + bool "fanotify permissions checking" + depends on FANOTIFY + depends on SECURITY + default n + ---help--- + Say Y here is you want fanotify listeners to be able to make permissions + decisions concerning filesystem events. This is used by some fanotify + listeners which need to scan files before allowing the system access to + use those files. This is used by some anti-malware vendors and by some + hierarchical storage managent systems. + + If unsure, say N. diff --git a/kernel/fs/notify/fanotify/Makefile b/kernel/fs/notify/fanotify/Makefile new file mode 100644 index 000000000..0999213e7 --- /dev/null +++ b/kernel/fs/notify/fanotify/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_FANOTIFY) += fanotify.o fanotify_user.o diff --git a/kernel/fs/notify/fanotify/fanotify.c b/kernel/fs/notify/fanotify/fanotify.c new file mode 100644 index 000000000..d2f97ecca --- /dev/null +++ b/kernel/fs/notify/fanotify/fanotify.c @@ -0,0 +1,270 @@ +#include <linux/fanotify.h> +#include <linux/fdtable.h> +#include <linux/fsnotify_backend.h> +#include <linux/init.h> +#include <linux/jiffies.h> +#include <linux/kernel.h> /* UINT_MAX */ +#include <linux/mount.h> +#include <linux/sched.h> +#include <linux/types.h> +#include <linux/wait.h> + +#include "fanotify.h" + +static bool should_merge(struct fsnotify_event *old_fsn, + struct fsnotify_event *new_fsn) +{ + struct fanotify_event_info *old, *new; + + pr_debug("%s: old=%p new=%p\n", __func__, old_fsn, new_fsn); + old = FANOTIFY_E(old_fsn); + new = FANOTIFY_E(new_fsn); + + if (old_fsn->inode == new_fsn->inode && old->tgid == new->tgid && + old->path.mnt == new->path.mnt && + old->path.dentry == new->path.dentry) + return true; + return false; +} + +/* and the list better be locked by something too! */ +static int fanotify_merge(struct list_head *list, struct fsnotify_event *event) +{ + struct fsnotify_event *test_event; + bool do_merge = false; + + pr_debug("%s: list=%p event=%p\n", __func__, list, event); + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + /* + * Don't merge a permission event with any other event so that we know + * the event structure we have created in fanotify_handle_event() is the + * one we should check for permission response. + */ + if (event->mask & FAN_ALL_PERM_EVENTS) + return 0; +#endif + + list_for_each_entry_reverse(test_event, list, list) { + if (should_merge(test_event, event)) { + do_merge = true; + break; + } + } + + if (!do_merge) + return 0; + + test_event->mask |= event->mask; + return 1; +} + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS +static int fanotify_get_response(struct fsnotify_group *group, + struct fanotify_perm_event_info *event) +{ + int ret; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + wait_event(group->fanotify_data.access_waitq, event->response || + atomic_read(&group->fanotify_data.bypass_perm)); + + if (!event->response) { /* bypass_perm set */ + /* + * Event was canceled because group is being destroyed. Remove + * it from group's event list because we are responsible for + * freeing the permission event. + */ + fsnotify_remove_event(group, &event->fae.fse); + return 0; + } + + /* userspace responded, convert to something usable */ + switch (event->response) { + case FAN_ALLOW: + ret = 0; + break; + case FAN_DENY: + default: + ret = -EPERM; + } + event->response = 0; + + pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__, + group, event, ret); + + return ret; +} +#endif + +static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark, + struct fsnotify_mark *vfsmnt_mark, + u32 event_mask, + void *data, int data_type) +{ + __u32 marks_mask, marks_ignored_mask; + struct path *path = data; + + pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p" + " data_type=%d\n", __func__, inode_mark, vfsmnt_mark, + event_mask, data, data_type); + + /* if we don't have enough info to send an event to userspace say no */ + if (data_type != FSNOTIFY_EVENT_PATH) + return false; + + /* sorry, fanotify only gives a damn about files and dirs */ + if (!d_is_reg(path->dentry) && + !d_can_lookup(path->dentry)) + return false; + + if (inode_mark && vfsmnt_mark) { + marks_mask = (vfsmnt_mark->mask | inode_mark->mask); + marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask); + } else if (inode_mark) { + /* + * if the event is for a child and this inode doesn't care about + * events on the child, don't send it! + */ + if ((event_mask & FS_EVENT_ON_CHILD) && + !(inode_mark->mask & FS_EVENT_ON_CHILD)) + return false; + marks_mask = inode_mark->mask; + marks_ignored_mask = inode_mark->ignored_mask; + } else if (vfsmnt_mark) { + marks_mask = vfsmnt_mark->mask; + marks_ignored_mask = vfsmnt_mark->ignored_mask; + } else { + BUG(); + } + + if (d_is_dir(path->dentry) && + !(marks_mask & FS_ISDIR & ~marks_ignored_mask)) + return false; + + if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask & + ~marks_ignored_mask) + return true; + + return false; +} + +struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask, + struct path *path) +{ + struct fanotify_event_info *event; + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (mask & FAN_ALL_PERM_EVENTS) { + struct fanotify_perm_event_info *pevent; + + pevent = kmem_cache_alloc(fanotify_perm_event_cachep, + GFP_KERNEL); + if (!pevent) + return NULL; + event = &pevent->fae; + pevent->response = 0; + goto init; + } +#endif + event = kmem_cache_alloc(fanotify_event_cachep, GFP_KERNEL); + if (!event) + return NULL; +init: __maybe_unused + fsnotify_init_event(&event->fse, inode, mask); + event->tgid = get_pid(task_tgid(current)); + if (path) { + event->path = *path; + path_get(&event->path); + } else { + event->path.mnt = NULL; + event->path.dentry = NULL; + } + return event; +} + +static int fanotify_handle_event(struct fsnotify_group *group, + struct inode *inode, + struct fsnotify_mark *inode_mark, + struct fsnotify_mark *fanotify_mark, + u32 mask, void *data, int data_type, + const unsigned char *file_name, u32 cookie) +{ + int ret = 0; + struct fanotify_event_info *event; + struct fsnotify_event *fsn_event; + + BUILD_BUG_ON(FAN_ACCESS != FS_ACCESS); + BUILD_BUG_ON(FAN_MODIFY != FS_MODIFY); + BUILD_BUG_ON(FAN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); + BUILD_BUG_ON(FAN_CLOSE_WRITE != FS_CLOSE_WRITE); + BUILD_BUG_ON(FAN_OPEN != FS_OPEN); + BUILD_BUG_ON(FAN_EVENT_ON_CHILD != FS_EVENT_ON_CHILD); + BUILD_BUG_ON(FAN_Q_OVERFLOW != FS_Q_OVERFLOW); + BUILD_BUG_ON(FAN_OPEN_PERM != FS_OPEN_PERM); + BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM); + BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR); + + if (!fanotify_should_send_event(inode_mark, fanotify_mark, mask, data, + data_type)) + return 0; + + pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, + mask); + + event = fanotify_alloc_event(inode, mask, data); + if (unlikely(!event)) + return -ENOMEM; + + fsn_event = &event->fse; + ret = fsnotify_add_event(group, fsn_event, fanotify_merge); + if (ret) { + /* Permission events shouldn't be merged */ + BUG_ON(ret == 1 && mask & FAN_ALL_PERM_EVENTS); + /* Our event wasn't used in the end. Free it. */ + fsnotify_destroy_event(group, fsn_event); + + return 0; + } + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (mask & FAN_ALL_PERM_EVENTS) { + ret = fanotify_get_response(group, FANOTIFY_PE(fsn_event)); + fsnotify_destroy_event(group, fsn_event); + } +#endif + return ret; +} + +static void fanotify_free_group_priv(struct fsnotify_group *group) +{ + struct user_struct *user; + + user = group->fanotify_data.user; + atomic_dec(&user->fanotify_listeners); + free_uid(user); +} + +static void fanotify_free_event(struct fsnotify_event *fsn_event) +{ + struct fanotify_event_info *event; + + event = FANOTIFY_E(fsn_event); + path_put(&event->path); + put_pid(event->tgid); +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (fsn_event->mask & FAN_ALL_PERM_EVENTS) { + kmem_cache_free(fanotify_perm_event_cachep, + FANOTIFY_PE(fsn_event)); + return; + } +#endif + kmem_cache_free(fanotify_event_cachep, event); +} + +const struct fsnotify_ops fanotify_fsnotify_ops = { + .handle_event = fanotify_handle_event, + .free_group_priv = fanotify_free_group_priv, + .free_event = fanotify_free_event, +}; diff --git a/kernel/fs/notify/fanotify/fanotify.h b/kernel/fs/notify/fanotify/fanotify.h new file mode 100644 index 000000000..2a5fb1411 --- /dev/null +++ b/kernel/fs/notify/fanotify/fanotify.h @@ -0,0 +1,50 @@ +#include <linux/fsnotify_backend.h> +#include <linux/path.h> +#include <linux/slab.h> + +extern struct kmem_cache *fanotify_event_cachep; +extern struct kmem_cache *fanotify_perm_event_cachep; + +/* + * Structure for normal fanotify events. It gets allocated in + * fanotify_handle_event() and freed when the information is retrieved by + * userspace + */ +struct fanotify_event_info { + struct fsnotify_event fse; + /* + * We hold ref to this path so it may be dereferenced at any point + * during this object's lifetime + */ + struct path path; + struct pid *tgid; +}; + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS +/* + * Structure for permission fanotify events. It gets allocated and freed in + * fanotify_handle_event() since we wait there for user response. When the + * information is retrieved by userspace the structure is moved from + * group->notification_list to group->fanotify_data.access_list to wait for + * user response. + */ +struct fanotify_perm_event_info { + struct fanotify_event_info fae; + int response; /* userspace answer to question */ + int fd; /* fd we passed to userspace for this event */ +}; + +static inline struct fanotify_perm_event_info * +FANOTIFY_PE(struct fsnotify_event *fse) +{ + return container_of(fse, struct fanotify_perm_event_info, fae.fse); +} +#endif + +static inline struct fanotify_event_info *FANOTIFY_E(struct fsnotify_event *fse) +{ + return container_of(fse, struct fanotify_event_info, fse); +} + +struct fanotify_event_info *fanotify_alloc_event(struct inode *inode, u32 mask, + struct path *path); diff --git a/kernel/fs/notify/fanotify/fanotify_user.c b/kernel/fs/notify/fanotify/fanotify_user.c new file mode 100644 index 000000000..cf275500a --- /dev/null +++ b/kernel/fs/notify/fanotify/fanotify_user.c @@ -0,0 +1,940 @@ +#include <linux/fanotify.h> +#include <linux/fcntl.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/anon_inodes.h> +#include <linux/fsnotify_backend.h> +#include <linux/init.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/poll.h> +#include <linux/security.h> +#include <linux/syscalls.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/uaccess.h> +#include <linux/compat.h> + +#include <asm/ioctls.h> + +#include "../../mount.h" +#include "../fdinfo.h" +#include "fanotify.h" + +#define FANOTIFY_DEFAULT_MAX_EVENTS 16384 +#define FANOTIFY_DEFAULT_MAX_MARKS 8192 +#define FANOTIFY_DEFAULT_MAX_LISTENERS 128 + +/* + * All flags that may be specified in parameter event_f_flags of fanotify_init. + * + * Internal and external open flags are stored together in field f_flags of + * struct file. Only external open flags shall be allowed in event_f_flags. + * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be + * excluded. + */ +#define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \ + O_ACCMODE | O_APPEND | O_NONBLOCK | \ + __O_SYNC | O_DSYNC | O_CLOEXEC | \ + O_LARGEFILE | O_NOATIME ) + +extern const struct fsnotify_ops fanotify_fsnotify_ops; + +static struct kmem_cache *fanotify_mark_cache __read_mostly; +struct kmem_cache *fanotify_event_cachep __read_mostly; +struct kmem_cache *fanotify_perm_event_cachep __read_mostly; + +/* + * Get an fsnotify notification event if one exists and is small + * enough to fit in "count". Return an error pointer if the count + * is not large enough. + * + * Called with the group->notification_mutex held. + */ +static struct fsnotify_event *get_one_event(struct fsnotify_group *group, + size_t count) +{ + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + + pr_debug("%s: group=%p count=%zd\n", __func__, group, count); + + if (fsnotify_notify_queue_is_empty(group)) + return NULL; + + if (FAN_EVENT_METADATA_LEN > count) + return ERR_PTR(-EINVAL); + + /* held the notification_mutex the whole time, so this is the + * same event we peeked above */ + return fsnotify_remove_first_event(group); +} + +static int create_fd(struct fsnotify_group *group, + struct fanotify_event_info *event, + struct file **file) +{ + int client_fd; + struct file *new_file; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + client_fd = get_unused_fd_flags(group->fanotify_data.f_flags); + if (client_fd < 0) + return client_fd; + + /* + * we need a new file handle for the userspace program so it can read even if it was + * originally opened O_WRONLY. + */ + /* it's possible this event was an overflow event. in that case dentry and mnt + * are NULL; That's fine, just don't call dentry open */ + if (event->path.dentry && event->path.mnt) + new_file = dentry_open(&event->path, + group->fanotify_data.f_flags | FMODE_NONOTIFY, + current_cred()); + else + new_file = ERR_PTR(-EOVERFLOW); + if (IS_ERR(new_file)) { + /* + * we still send an event even if we can't open the file. this + * can happen when say tasks are gone and we try to open their + * /proc files or we try to open a WRONLY file like in sysfs + * we just send the errno to userspace since there isn't much + * else we can do. + */ + put_unused_fd(client_fd); + client_fd = PTR_ERR(new_file); + } else { + *file = new_file; + } + + return client_fd; +} + +static int fill_event_metadata(struct fsnotify_group *group, + struct fanotify_event_metadata *metadata, + struct fsnotify_event *fsn_event, + struct file **file) +{ + int ret = 0; + struct fanotify_event_info *event; + + pr_debug("%s: group=%p metadata=%p event=%p\n", __func__, + group, metadata, fsn_event); + + *file = NULL; + event = container_of(fsn_event, struct fanotify_event_info, fse); + metadata->event_len = FAN_EVENT_METADATA_LEN; + metadata->metadata_len = FAN_EVENT_METADATA_LEN; + metadata->vers = FANOTIFY_METADATA_VERSION; + metadata->reserved = 0; + metadata->mask = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS; + metadata->pid = pid_vnr(event->tgid); + if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW)) + metadata->fd = FAN_NOFD; + else { + metadata->fd = create_fd(group, event, file); + if (metadata->fd < 0) + ret = metadata->fd; + } + + return ret; +} + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS +static struct fanotify_perm_event_info *dequeue_event( + struct fsnotify_group *group, int fd) +{ + struct fanotify_perm_event_info *event, *return_e = NULL; + + spin_lock(&group->fanotify_data.access_lock); + list_for_each_entry(event, &group->fanotify_data.access_list, + fae.fse.list) { + if (event->fd != fd) + continue; + + list_del_init(&event->fae.fse.list); + return_e = event; + break; + } + spin_unlock(&group->fanotify_data.access_lock); + + pr_debug("%s: found return_re=%p\n", __func__, return_e); + + return return_e; +} + +static int process_access_response(struct fsnotify_group *group, + struct fanotify_response *response_struct) +{ + struct fanotify_perm_event_info *event; + int fd = response_struct->fd; + int response = response_struct->response; + + pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, + fd, response); + /* + * make sure the response is valid, if invalid we do nothing and either + * userspace can send a valid response or we will clean it up after the + * timeout + */ + switch (response) { + case FAN_ALLOW: + case FAN_DENY: + break; + default: + return -EINVAL; + } + + if (fd < 0) + return -EINVAL; + + event = dequeue_event(group, fd); + if (!event) + return -ENOENT; + + event->response = response; + wake_up(&group->fanotify_data.access_waitq); + + return 0; +} +#endif + +static ssize_t copy_event_to_user(struct fsnotify_group *group, + struct fsnotify_event *event, + char __user *buf) +{ + struct fanotify_event_metadata fanotify_event_metadata; + struct file *f; + int fd, ret; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f); + if (ret < 0) + return ret; + + fd = fanotify_event_metadata.fd; + ret = -EFAULT; + if (copy_to_user(buf, &fanotify_event_metadata, + fanotify_event_metadata.event_len)) + goto out_close_fd; + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (event->mask & FAN_ALL_PERM_EVENTS) + FANOTIFY_PE(event)->fd = fd; +#endif + + if (fd != FAN_NOFD) + fd_install(fd, f); + return fanotify_event_metadata.event_len; + +out_close_fd: + if (fd != FAN_NOFD) { + put_unused_fd(fd); + fput(f); + } + return ret; +} + +/* intofiy userspace file descriptor functions */ +static unsigned int fanotify_poll(struct file *file, poll_table *wait) +{ + struct fsnotify_group *group = file->private_data; + int ret = 0; + + poll_wait(file, &group->notification_waitq, wait); + mutex_lock(&group->notification_mutex); + if (!fsnotify_notify_queue_is_empty(group)) + ret = POLLIN | POLLRDNORM; + mutex_unlock(&group->notification_mutex); + + return ret; +} + +static ssize_t fanotify_read(struct file *file, char __user *buf, + size_t count, loff_t *pos) +{ + struct fsnotify_group *group; + struct fsnotify_event *kevent; + char __user *start; + int ret; + DEFINE_WAIT_FUNC(wait, woken_wake_function); + + start = buf; + group = file->private_data; + + pr_debug("%s: group=%p\n", __func__, group); + + add_wait_queue(&group->notification_waitq, &wait); + while (1) { + mutex_lock(&group->notification_mutex); + kevent = get_one_event(group, count); + mutex_unlock(&group->notification_mutex); + + if (IS_ERR(kevent)) { + ret = PTR_ERR(kevent); + break; + } + + if (!kevent) { + ret = -EAGAIN; + if (file->f_flags & O_NONBLOCK) + break; + + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + + if (start != buf) + break; + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + continue; + } + + ret = copy_event_to_user(group, kevent, buf); + /* + * Permission events get queued to wait for response. Other + * events can be destroyed now. + */ + if (!(kevent->mask & FAN_ALL_PERM_EVENTS)) { + fsnotify_destroy_event(group, kevent); + if (ret < 0) + break; + } else { +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (ret < 0) { + FANOTIFY_PE(kevent)->response = FAN_DENY; + wake_up(&group->fanotify_data.access_waitq); + break; + } + spin_lock(&group->fanotify_data.access_lock); + list_add_tail(&kevent->list, + &group->fanotify_data.access_list); + spin_unlock(&group->fanotify_data.access_lock); +#endif + } + buf += ret; + count -= ret; + } + remove_wait_queue(&group->notification_waitq, &wait); + + if (start != buf && ret != -EFAULT) + ret = buf - start; + return ret; +} + +static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) +{ +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + struct fanotify_response response = { .fd = -1, .response = -1 }; + struct fsnotify_group *group; + int ret; + + group = file->private_data; + + if (count > sizeof(response)) + count = sizeof(response); + + pr_debug("%s: group=%p count=%zu\n", __func__, group, count); + + if (copy_from_user(&response, buf, count)) + return -EFAULT; + + ret = process_access_response(group, &response); + if (ret < 0) + count = ret; + + return count; +#else + return -EINVAL; +#endif +} + +static int fanotify_release(struct inode *ignored, struct file *file) +{ + struct fsnotify_group *group = file->private_data; + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + struct fanotify_perm_event_info *event, *next; + + /* + * There may be still new events arriving in the notification queue + * but since userspace cannot use fanotify fd anymore, no event can + * enter or leave access_list by now. + */ + spin_lock(&group->fanotify_data.access_lock); + + atomic_inc(&group->fanotify_data.bypass_perm); + + list_for_each_entry_safe(event, next, &group->fanotify_data.access_list, + fae.fse.list) { + pr_debug("%s: found group=%p event=%p\n", __func__, group, + event); + + list_del_init(&event->fae.fse.list); + event->response = FAN_ALLOW; + } + spin_unlock(&group->fanotify_data.access_lock); + + /* + * Since bypass_perm is set, newly queued events will not wait for + * access response. Wake up the already sleeping ones now. + * synchronize_srcu() in fsnotify_destroy_group() will wait for all + * processes sleeping in fanotify_handle_event() waiting for access + * response and thus also for all permission events to be freed. + */ + wake_up(&group->fanotify_data.access_waitq); +#endif + + /* matches the fanotify_init->fsnotify_alloc_group */ + fsnotify_destroy_group(group); + + return 0; +} + +static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct fsnotify_group *group; + struct fsnotify_event *fsn_event; + void __user *p; + int ret = -ENOTTY; + size_t send_len = 0; + + group = file->private_data; + + p = (void __user *) arg; + + switch (cmd) { + case FIONREAD: + mutex_lock(&group->notification_mutex); + list_for_each_entry(fsn_event, &group->notification_list, list) + send_len += FAN_EVENT_METADATA_LEN; + mutex_unlock(&group->notification_mutex); + ret = put_user(send_len, (int __user *) p); + break; + } + + return ret; +} + +static const struct file_operations fanotify_fops = { + .show_fdinfo = fanotify_show_fdinfo, + .poll = fanotify_poll, + .read = fanotify_read, + .write = fanotify_write, + .fasync = NULL, + .release = fanotify_release, + .unlocked_ioctl = fanotify_ioctl, + .compat_ioctl = fanotify_ioctl, + .llseek = noop_llseek, +}; + +static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + kmem_cache_free(fanotify_mark_cache, fsn_mark); +} + +static int fanotify_find_path(int dfd, const char __user *filename, + struct path *path, unsigned int flags) +{ + int ret; + + pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, + dfd, filename, flags); + + if (filename == NULL) { + struct fd f = fdget(dfd); + + ret = -EBADF; + if (!f.file) + goto out; + + ret = -ENOTDIR; + if ((flags & FAN_MARK_ONLYDIR) && + !(S_ISDIR(file_inode(f.file)->i_mode))) { + fdput(f); + goto out; + } + + *path = f.file->f_path; + path_get(path); + fdput(f); + } else { + unsigned int lookup_flags = 0; + + if (!(flags & FAN_MARK_DONT_FOLLOW)) + lookup_flags |= LOOKUP_FOLLOW; + if (flags & FAN_MARK_ONLYDIR) + lookup_flags |= LOOKUP_DIRECTORY; + + ret = user_path_at(dfd, filename, lookup_flags, path); + if (ret) + goto out; + } + + /* you can only watch an inode if you have read permissions on it */ + ret = inode_permission(path->dentry->d_inode, MAY_READ); + if (ret) + path_put(path); +out: + return ret; +} + +static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, + __u32 mask, + unsigned int flags, + int *destroy) +{ + __u32 oldmask = 0; + + spin_lock(&fsn_mark->lock); + if (!(flags & FAN_MARK_IGNORED_MASK)) { + __u32 tmask = fsn_mark->mask & ~mask; + + if (flags & FAN_MARK_ONDIR) + tmask &= ~FAN_ONDIR; + + oldmask = fsn_mark->mask; + fsnotify_set_mark_mask_locked(fsn_mark, tmask); + } else { + __u32 tmask = fsn_mark->ignored_mask & ~mask; + if (flags & FAN_MARK_ONDIR) + tmask &= ~FAN_ONDIR; + + fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); + } + *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask); + spin_unlock(&fsn_mark->lock); + + return mask & oldmask; +} + +static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt, __u32 mask, + unsigned int flags) +{ + struct fsnotify_mark *fsn_mark = NULL; + __u32 removed; + int destroy_mark; + + mutex_lock(&group->mark_mutex); + fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); + if (!fsn_mark) { + mutex_unlock(&group->mark_mutex); + return -ENOENT; + } + + removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, + &destroy_mark); + if (destroy_mark) + fsnotify_destroy_mark_locked(fsn_mark, group); + mutex_unlock(&group->mark_mutex); + + fsnotify_put_mark(fsn_mark); + if (removed & real_mount(mnt)->mnt_fsnotify_mask) + fsnotify_recalc_vfsmount_mask(mnt); + + return 0; +} + +static int fanotify_remove_inode_mark(struct fsnotify_group *group, + struct inode *inode, __u32 mask, + unsigned int flags) +{ + struct fsnotify_mark *fsn_mark = NULL; + __u32 removed; + int destroy_mark; + + mutex_lock(&group->mark_mutex); + fsn_mark = fsnotify_find_inode_mark(group, inode); + if (!fsn_mark) { + mutex_unlock(&group->mark_mutex); + return -ENOENT; + } + + removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags, + &destroy_mark); + if (destroy_mark) + fsnotify_destroy_mark_locked(fsn_mark, group); + mutex_unlock(&group->mark_mutex); + + /* matches the fsnotify_find_inode_mark() */ + fsnotify_put_mark(fsn_mark); + if (removed & inode->i_fsnotify_mask) + fsnotify_recalc_inode_mask(inode); + + return 0; +} + +static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, + __u32 mask, + unsigned int flags) +{ + __u32 oldmask = -1; + + spin_lock(&fsn_mark->lock); + if (!(flags & FAN_MARK_IGNORED_MASK)) { + __u32 tmask = fsn_mark->mask | mask; + + if (flags & FAN_MARK_ONDIR) + tmask |= FAN_ONDIR; + + oldmask = fsn_mark->mask; + fsnotify_set_mark_mask_locked(fsn_mark, tmask); + } else { + __u32 tmask = fsn_mark->ignored_mask | mask; + if (flags & FAN_MARK_ONDIR) + tmask |= FAN_ONDIR; + + fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); + if (flags & FAN_MARK_IGNORED_SURV_MODIFY) + fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; + } + spin_unlock(&fsn_mark->lock); + + return mask & ~oldmask; +} + +static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group, + struct inode *inode, + struct vfsmount *mnt) +{ + struct fsnotify_mark *mark; + int ret; + + if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) + return ERR_PTR(-ENOSPC); + + mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); + if (!mark) + return ERR_PTR(-ENOMEM); + + fsnotify_init_mark(mark, fanotify_free_mark); + ret = fsnotify_add_mark_locked(mark, group, inode, mnt, 0); + if (ret) { + fsnotify_put_mark(mark); + return ERR_PTR(ret); + } + + return mark; +} + + +static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt, __u32 mask, + unsigned int flags) +{ + struct fsnotify_mark *fsn_mark; + __u32 added; + + mutex_lock(&group->mark_mutex); + fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); + if (!fsn_mark) { + fsn_mark = fanotify_add_new_mark(group, NULL, mnt); + if (IS_ERR(fsn_mark)) { + mutex_unlock(&group->mark_mutex); + return PTR_ERR(fsn_mark); + } + } + added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); + mutex_unlock(&group->mark_mutex); + + if (added & ~real_mount(mnt)->mnt_fsnotify_mask) + fsnotify_recalc_vfsmount_mask(mnt); + + fsnotify_put_mark(fsn_mark); + return 0; +} + +static int fanotify_add_inode_mark(struct fsnotify_group *group, + struct inode *inode, __u32 mask, + unsigned int flags) +{ + struct fsnotify_mark *fsn_mark; + __u32 added; + + pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); + + /* + * If some other task has this inode open for write we should not add + * an ignored mark, unless that ignored mark is supposed to survive + * modification changes anyway. + */ + if ((flags & FAN_MARK_IGNORED_MASK) && + !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && + (atomic_read(&inode->i_writecount) > 0)) + return 0; + + mutex_lock(&group->mark_mutex); + fsn_mark = fsnotify_find_inode_mark(group, inode); + if (!fsn_mark) { + fsn_mark = fanotify_add_new_mark(group, inode, NULL); + if (IS_ERR(fsn_mark)) { + mutex_unlock(&group->mark_mutex); + return PTR_ERR(fsn_mark); + } + } + added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); + mutex_unlock(&group->mark_mutex); + + if (added & ~inode->i_fsnotify_mask) + fsnotify_recalc_inode_mask(inode); + + fsnotify_put_mark(fsn_mark); + return 0; +} + +/* fanotify syscalls */ +SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) +{ + struct fsnotify_group *group; + int f_flags, fd; + struct user_struct *user; + struct fanotify_event_info *oevent; + + pr_debug("%s: flags=%d event_f_flags=%d\n", + __func__, flags, event_f_flags); + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (flags & ~FAN_ALL_INIT_FLAGS) + return -EINVAL; + + if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS) + return -EINVAL; + + switch (event_f_flags & O_ACCMODE) { + case O_RDONLY: + case O_RDWR: + case O_WRONLY: + break; + default: + return -EINVAL; + } + + user = get_current_user(); + if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { + free_uid(user); + return -EMFILE; + } + + f_flags = O_RDWR | FMODE_NONOTIFY; + if (flags & FAN_CLOEXEC) + f_flags |= O_CLOEXEC; + if (flags & FAN_NONBLOCK) + f_flags |= O_NONBLOCK; + + /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ + group = fsnotify_alloc_group(&fanotify_fsnotify_ops); + if (IS_ERR(group)) { + free_uid(user); + return PTR_ERR(group); + } + + group->fanotify_data.user = user; + atomic_inc(&user->fanotify_listeners); + + oevent = fanotify_alloc_event(NULL, FS_Q_OVERFLOW, NULL); + if (unlikely(!oevent)) { + fd = -ENOMEM; + goto out_destroy_group; + } + group->overflow_event = &oevent->fse; + + if (force_o_largefile()) + event_f_flags |= O_LARGEFILE; + group->fanotify_data.f_flags = event_f_flags; +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + spin_lock_init(&group->fanotify_data.access_lock); + init_waitqueue_head(&group->fanotify_data.access_waitq); + INIT_LIST_HEAD(&group->fanotify_data.access_list); + atomic_set(&group->fanotify_data.bypass_perm, 0); +#endif + switch (flags & FAN_ALL_CLASS_BITS) { + case FAN_CLASS_NOTIF: + group->priority = FS_PRIO_0; + break; + case FAN_CLASS_CONTENT: + group->priority = FS_PRIO_1; + break; + case FAN_CLASS_PRE_CONTENT: + group->priority = FS_PRIO_2; + break; + default: + fd = -EINVAL; + goto out_destroy_group; + } + + if (flags & FAN_UNLIMITED_QUEUE) { + fd = -EPERM; + if (!capable(CAP_SYS_ADMIN)) + goto out_destroy_group; + group->max_events = UINT_MAX; + } else { + group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; + } + + if (flags & FAN_UNLIMITED_MARKS) { + fd = -EPERM; + if (!capable(CAP_SYS_ADMIN)) + goto out_destroy_group; + group->fanotify_data.max_marks = UINT_MAX; + } else { + group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; + } + + fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); + if (fd < 0) + goto out_destroy_group; + + return fd; + +out_destroy_group: + fsnotify_destroy_group(group); + return fd; +} + +SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags, + __u64, mask, int, dfd, + const char __user *, pathname) +{ + struct inode *inode = NULL; + struct vfsmount *mnt = NULL; + struct fsnotify_group *group; + struct fd f; + struct path path; + int ret; + + pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", + __func__, fanotify_fd, flags, dfd, pathname, mask); + + /* we only use the lower 32 bits as of right now. */ + if (mask & ((__u64)0xffffffff << 32)) + return -EINVAL; + + if (flags & ~FAN_ALL_MARK_FLAGS) + return -EINVAL; + switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { + case FAN_MARK_ADD: /* fallthrough */ + case FAN_MARK_REMOVE: + if (!mask) + return -EINVAL; + break; + case FAN_MARK_FLUSH: + if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH)) + return -EINVAL; + break; + default: + return -EINVAL; + } + + if (mask & FAN_ONDIR) { + flags |= FAN_MARK_ONDIR; + mask &= ~FAN_ONDIR; + } + +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD)) +#else + if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD)) +#endif + return -EINVAL; + + f = fdget(fanotify_fd); + if (unlikely(!f.file)) + return -EBADF; + + /* verify that this is indeed an fanotify instance */ + ret = -EINVAL; + if (unlikely(f.file->f_op != &fanotify_fops)) + goto fput_and_out; + group = f.file->private_data; + + /* + * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not + * allowed to set permissions events. + */ + ret = -EINVAL; + if (mask & FAN_ALL_PERM_EVENTS && + group->priority == FS_PRIO_0) + goto fput_and_out; + + if (flags & FAN_MARK_FLUSH) { + ret = 0; + if (flags & FAN_MARK_MOUNT) + fsnotify_clear_vfsmount_marks_by_group(group); + else + fsnotify_clear_inode_marks_by_group(group); + goto fput_and_out; + } + + ret = fanotify_find_path(dfd, pathname, &path, flags); + if (ret) + goto fput_and_out; + + /* inode held in place by reference to path; group by fget on fd */ + if (!(flags & FAN_MARK_MOUNT)) + inode = path.dentry->d_inode; + else + mnt = path.mnt; + + /* create/update an inode mark */ + switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) { + case FAN_MARK_ADD: + if (flags & FAN_MARK_MOUNT) + ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags); + else + ret = fanotify_add_inode_mark(group, inode, mask, flags); + break; + case FAN_MARK_REMOVE: + if (flags & FAN_MARK_MOUNT) + ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags); + else + ret = fanotify_remove_inode_mark(group, inode, mask, flags); + break; + default: + ret = -EINVAL; + } + + path_put(&path); +fput_and_out: + fdput(f); + return ret; +} + +#ifdef CONFIG_COMPAT +COMPAT_SYSCALL_DEFINE6(fanotify_mark, + int, fanotify_fd, unsigned int, flags, + __u32, mask0, __u32, mask1, int, dfd, + const char __user *, pathname) +{ + return sys_fanotify_mark(fanotify_fd, flags, +#ifdef __BIG_ENDIAN + ((__u64)mask0 << 32) | mask1, +#else + ((__u64)mask1 << 32) | mask0, +#endif + dfd, pathname); +} +#endif + +/* + * fanotify_user_setup - Our initialization function. Note that we cannot return + * error because we have compiled-in VFS hooks. So an (unlikely) failure here + * must result in panic(). + */ +static int __init fanotify_user_setup(void) +{ + fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); + fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC); +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + fanotify_perm_event_cachep = KMEM_CACHE(fanotify_perm_event_info, + SLAB_PANIC); +#endif + + return 0; +} +device_initcall(fanotify_user_setup); diff --git a/kernel/fs/notify/fdinfo.c b/kernel/fs/notify/fdinfo.c new file mode 100644 index 000000000..58b7cdb63 --- /dev/null +++ b/kernel/fs/notify/fdinfo.c @@ -0,0 +1,165 @@ +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/fsnotify_backend.h> +#include <linux/idr.h> +#include <linux/init.h> +#include <linux/inotify.h> +#include <linux/fanotify.h> +#include <linux/kernel.h> +#include <linux/namei.h> +#include <linux/sched.h> +#include <linux/types.h> +#include <linux/seq_file.h> +#include <linux/proc_fs.h> +#include <linux/exportfs.h> + +#include "inotify/inotify.h" +#include "../fs/mount.h" + +#if defined(CONFIG_PROC_FS) + +#if defined(CONFIG_INOTIFY_USER) || defined(CONFIG_FANOTIFY) + +static void show_fdinfo(struct seq_file *m, struct file *f, + void (*show)(struct seq_file *m, + struct fsnotify_mark *mark)) +{ + struct fsnotify_group *group = f->private_data; + struct fsnotify_mark *mark; + + mutex_lock(&group->mark_mutex); + list_for_each_entry(mark, &group->marks_list, g_list) { + show(m, mark); + if (seq_has_overflowed(m)) + break; + } + mutex_unlock(&group->mark_mutex); +} + +#if defined(CONFIG_EXPORTFS) +static void show_mark_fhandle(struct seq_file *m, struct inode *inode) +{ + struct { + struct file_handle handle; + u8 pad[MAX_HANDLE_SZ]; + } f; + int size, ret, i; + + f.handle.handle_bytes = sizeof(f.pad); + size = f.handle.handle_bytes >> 2; + + ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, 0); + if ((ret == FILEID_INVALID) || (ret < 0)) { + WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret); + return; + } + + f.handle.handle_type = ret; + f.handle.handle_bytes = size * sizeof(u32); + + seq_printf(m, "fhandle-bytes:%x fhandle-type:%x f_handle:", + f.handle.handle_bytes, f.handle.handle_type); + + for (i = 0; i < f.handle.handle_bytes; i++) + seq_printf(m, "%02x", (int)f.handle.f_handle[i]); +} +#else +static void show_mark_fhandle(struct seq_file *m, struct inode *inode) +{ +} +#endif + +#ifdef CONFIG_INOTIFY_USER + +static void inotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark) +{ + struct inotify_inode_mark *inode_mark; + struct inode *inode; + + if (!(mark->flags & (FSNOTIFY_MARK_FLAG_ALIVE | FSNOTIFY_MARK_FLAG_INODE))) + return; + + inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark); + inode = igrab(mark->inode); + if (inode) { + seq_printf(m, "inotify wd:%x ino:%lx sdev:%x mask:%x ignored_mask:%x ", + inode_mark->wd, inode->i_ino, inode->i_sb->s_dev, + mark->mask, mark->ignored_mask); + show_mark_fhandle(m, inode); + seq_putc(m, '\n'); + iput(inode); + } +} + +void inotify_show_fdinfo(struct seq_file *m, struct file *f) +{ + show_fdinfo(m, f, inotify_fdinfo); +} + +#endif /* CONFIG_INOTIFY_USER */ + +#ifdef CONFIG_FANOTIFY + +static void fanotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark) +{ + unsigned int mflags = 0; + struct inode *inode; + + if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) + return; + + if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY) + mflags |= FAN_MARK_IGNORED_SURV_MODIFY; + + if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) { + inode = igrab(mark->inode); + if (!inode) + return; + seq_printf(m, "fanotify ino:%lx sdev:%x mflags:%x mask:%x ignored_mask:%x ", + inode->i_ino, inode->i_sb->s_dev, + mflags, mark->mask, mark->ignored_mask); + show_mark_fhandle(m, inode); + seq_putc(m, '\n'); + iput(inode); + } else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT) { + struct mount *mnt = real_mount(mark->mnt); + + seq_printf(m, "fanotify mnt_id:%x mflags:%x mask:%x ignored_mask:%x\n", + mnt->mnt_id, mflags, mark->mask, mark->ignored_mask); + } +} + +void fanotify_show_fdinfo(struct seq_file *m, struct file *f) +{ + struct fsnotify_group *group = f->private_data; + unsigned int flags = 0; + + switch (group->priority) { + case FS_PRIO_0: + flags |= FAN_CLASS_NOTIF; + break; + case FS_PRIO_1: + flags |= FAN_CLASS_CONTENT; + break; + case FS_PRIO_2: + flags |= FAN_CLASS_PRE_CONTENT; + break; + } + + if (group->max_events == UINT_MAX) + flags |= FAN_UNLIMITED_QUEUE; + + if (group->fanotify_data.max_marks == UINT_MAX) + flags |= FAN_UNLIMITED_MARKS; + + seq_printf(m, "fanotify flags:%x event-flags:%x\n", + flags, group->fanotify_data.f_flags); + + show_fdinfo(m, f, fanotify_fdinfo); +} + +#endif /* CONFIG_FANOTIFY */ + +#endif /* CONFIG_INOTIFY_USER || CONFIG_FANOTIFY */ + +#endif /* CONFIG_PROC_FS */ diff --git a/kernel/fs/notify/fdinfo.h b/kernel/fs/notify/fdinfo.h new file mode 100644 index 000000000..9664c4904 --- /dev/null +++ b/kernel/fs/notify/fdinfo.h @@ -0,0 +1,27 @@ +#ifndef __FSNOTIFY_FDINFO_H__ +#define __FSNOTIFY_FDINFO_H__ + +#include <linux/errno.h> +#include <linux/proc_fs.h> + +struct seq_file; +struct file; + +#ifdef CONFIG_PROC_FS + +#ifdef CONFIG_INOTIFY_USER +void inotify_show_fdinfo(struct seq_file *m, struct file *f); +#endif + +#ifdef CONFIG_FANOTIFY +void fanotify_show_fdinfo(struct seq_file *m, struct file *f); +#endif + +#else /* CONFIG_PROC_FS */ + +#define inotify_show_fdinfo NULL +#define fanotify_show_fdinfo NULL + +#endif /* CONFIG_PROC_FS */ + +#endif /* __FSNOTIFY_FDINFO_H__ */ diff --git a/kernel/fs/notify/fsnotify.c b/kernel/fs/notify/fsnotify.c new file mode 100644 index 000000000..dd3fb0b17 --- /dev/null +++ b/kernel/fs/notify/fsnotify.c @@ -0,0 +1,299 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/dcache.h> +#include <linux/fs.h> +#include <linux/gfp.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/mount.h> +#include <linux/srcu.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" +#include "../mount.h" + +/* + * Clear all of the marks on an inode when it is being evicted from core + */ +void __fsnotify_inode_delete(struct inode *inode) +{ + fsnotify_clear_marks_by_inode(inode); +} +EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); + +void __fsnotify_vfsmount_delete(struct vfsmount *mnt) +{ + fsnotify_clear_marks_by_mount(mnt); +} + +/* + * Given an inode, first check if we care what happens to our children. Inotify + * and dnotify both tell their parents about events. If we care about any event + * on a child we run all of our children and set a dentry flag saying that the + * parent cares. Thus when an event happens on a child it can quickly tell if + * if there is a need to find a parent and send the event to the parent. + */ +void __fsnotify_update_child_dentry_flags(struct inode *inode) +{ + struct dentry *alias; + int watched; + + if (!S_ISDIR(inode->i_mode)) + return; + + /* determine if the children should tell inode about their events */ + watched = fsnotify_inode_watches_children(inode); + + spin_lock(&inode->i_lock); + /* run all of the dentries associated with this inode. Since this is a + * directory, there damn well better only be one item on this list */ + hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { + struct dentry *child; + + /* run all of the children of the original inode and fix their + * d_flags to indicate parental interest (their parent is the + * original inode) */ + spin_lock(&alias->d_lock); + list_for_each_entry(child, &alias->d_subdirs, d_child) { + if (!child->d_inode) + continue; + + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + if (watched) + child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; + else + child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; + spin_unlock(&child->d_lock); + } + spin_unlock(&alias->d_lock); + } + spin_unlock(&inode->i_lock); +} + +/* Notify this dentry's parent about a child's events. */ +int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) +{ + struct dentry *parent; + struct inode *p_inode; + int ret = 0; + + if (!dentry) + dentry = path->dentry; + + if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) + return 0; + + parent = dget_parent(dentry); + p_inode = parent->d_inode; + + if (unlikely(!fsnotify_inode_watches_children(p_inode))) + __fsnotify_update_child_dentry_flags(p_inode); + else if (p_inode->i_fsnotify_mask & mask) { + /* we are notifying a parent so come up with the new mask which + * specifies these are events which came from a child. */ + mask |= FS_EVENT_ON_CHILD; + + if (path) + ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, + dentry->d_name.name, 0); + else + ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, + dentry->d_name.name, 0); + } + + dput(parent); + + return ret; +} +EXPORT_SYMBOL_GPL(__fsnotify_parent); + +static int send_to_group(struct inode *to_tell, + struct fsnotify_mark *inode_mark, + struct fsnotify_mark *vfsmount_mark, + __u32 mask, void *data, + int data_is, u32 cookie, + const unsigned char *file_name) +{ + struct fsnotify_group *group = NULL; + __u32 inode_test_mask = 0; + __u32 vfsmount_test_mask = 0; + + if (unlikely(!inode_mark && !vfsmount_mark)) { + BUG(); + return 0; + } + + /* clear ignored on inode modification */ + if (mask & FS_MODIFY) { + if (inode_mark && + !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) + inode_mark->ignored_mask = 0; + if (vfsmount_mark && + !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) + vfsmount_mark->ignored_mask = 0; + } + + /* does the inode mark tell us to do something? */ + if (inode_mark) { + group = inode_mark->group; + inode_test_mask = (mask & ~FS_EVENT_ON_CHILD); + inode_test_mask &= inode_mark->mask; + inode_test_mask &= ~inode_mark->ignored_mask; + } + + /* does the vfsmount_mark tell us to do something? */ + if (vfsmount_mark) { + vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD); + group = vfsmount_mark->group; + vfsmount_test_mask &= vfsmount_mark->mask; + vfsmount_test_mask &= ~vfsmount_mark->ignored_mask; + if (inode_mark) + vfsmount_test_mask &= ~inode_mark->ignored_mask; + } + + pr_debug("%s: group=%p to_tell=%p mask=%x inode_mark=%p" + " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x" + " data=%p data_is=%d cookie=%d\n", + __func__, group, to_tell, mask, inode_mark, + inode_test_mask, vfsmount_mark, vfsmount_test_mask, data, + data_is, cookie); + + if (!inode_test_mask && !vfsmount_test_mask) + return 0; + + return group->ops->handle_event(group, to_tell, inode_mark, + vfsmount_mark, mask, data, data_is, + file_name, cookie); +} + +/* + * This is the main call to fsnotify. The VFS calls into hook specific functions + * in linux/fsnotify.h. Those functions then in turn call here. Here will call + * out to all of the registered fsnotify_group. Those groups can then use the + * notification event in whatever means they feel necessary. + */ +int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, + const unsigned char *file_name, u32 cookie) +{ + struct hlist_node *inode_node = NULL, *vfsmount_node = NULL; + struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL; + struct fsnotify_group *inode_group, *vfsmount_group; + struct mount *mnt; + int idx, ret = 0; + /* global tests shouldn't care about events on child only the specific event */ + __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); + + if (data_is == FSNOTIFY_EVENT_PATH) + mnt = real_mount(((struct path *)data)->mnt); + else + mnt = NULL; + + /* + * if this is a modify event we may need to clear the ignored masks + * otherwise return if neither the inode nor the vfsmount care about + * this type of event. + */ + if (!(mask & FS_MODIFY) && + !(test_mask & to_tell->i_fsnotify_mask) && + !(mnt && test_mask & mnt->mnt_fsnotify_mask)) + return 0; + + idx = srcu_read_lock(&fsnotify_mark_srcu); + + if ((mask & FS_MODIFY) || + (test_mask & to_tell->i_fsnotify_mask)) + inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, + &fsnotify_mark_srcu); + + if (mnt && ((mask & FS_MODIFY) || + (test_mask & mnt->mnt_fsnotify_mask))) { + vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first, + &fsnotify_mark_srcu); + inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, + &fsnotify_mark_srcu); + } + + /* + * We need to merge inode & vfsmount mark lists so that inode mark + * ignore masks are properly reflected for mount mark notifications. + * That's why this traversal is so complicated... + */ + while (inode_node || vfsmount_node) { + inode_group = NULL; + inode_mark = NULL; + vfsmount_group = NULL; + vfsmount_mark = NULL; + + if (inode_node) { + inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu), + struct fsnotify_mark, obj_list); + inode_group = inode_mark->group; + } + + if (vfsmount_node) { + vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu), + struct fsnotify_mark, obj_list); + vfsmount_group = vfsmount_mark->group; + } + + if (inode_group && vfsmount_group) { + int cmp = fsnotify_compare_groups(inode_group, + vfsmount_group); + if (cmp > 0) { + inode_group = NULL; + inode_mark = NULL; + } else if (cmp < 0) { + vfsmount_group = NULL; + vfsmount_mark = NULL; + } + } + ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask, + data, data_is, cookie, file_name); + + if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS)) + goto out; + + if (inode_group) + inode_node = srcu_dereference(inode_node->next, + &fsnotify_mark_srcu); + if (vfsmount_group) + vfsmount_node = srcu_dereference(vfsmount_node->next, + &fsnotify_mark_srcu); + } + ret = 0; +out: + srcu_read_unlock(&fsnotify_mark_srcu, idx); + + return ret; +} +EXPORT_SYMBOL_GPL(fsnotify); + +static __init int fsnotify_init(void) +{ + int ret; + + BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); + + ret = init_srcu_struct(&fsnotify_mark_srcu); + if (ret) + panic("initializing fsnotify_mark_srcu"); + + return 0; +} +core_initcall(fsnotify_init); diff --git a/kernel/fs/notify/fsnotify.h b/kernel/fs/notify/fsnotify.h new file mode 100644 index 000000000..13a00be51 --- /dev/null +++ b/kernel/fs/notify/fsnotify.h @@ -0,0 +1,60 @@ +#ifndef __FS_NOTIFY_FSNOTIFY_H_ +#define __FS_NOTIFY_FSNOTIFY_H_ + +#include <linux/list.h> +#include <linux/fsnotify.h> +#include <linux/srcu.h> +#include <linux/types.h> + +/* destroy all events sitting in this groups notification queue */ +extern void fsnotify_flush_notify(struct fsnotify_group *group); + +/* protects reads of inode and vfsmount marks list */ +extern struct srcu_struct fsnotify_mark_srcu; + +/* Calculate mask of events for a list of marks */ +extern u32 fsnotify_recalc_mask(struct hlist_head *head); + +/* compare two groups for sorting of marks lists */ +extern int fsnotify_compare_groups(struct fsnotify_group *a, + struct fsnotify_group *b); + +extern void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *fsn_mark, + __u32 mask); +/* Add mark to a proper place in mark list */ +extern int fsnotify_add_mark_list(struct hlist_head *head, + struct fsnotify_mark *mark, + int allow_dups); +/* add a mark to an inode */ +extern int fsnotify_add_inode_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group, struct inode *inode, + int allow_dups); +/* add a mark to a vfsmount */ +extern int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group, struct vfsmount *mnt, + int allow_dups); + +/* vfsmount specific destruction of a mark */ +extern void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark); +/* inode specific destruction of a mark */ +extern void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark); +/* Destroy all marks in the given list */ +extern void fsnotify_destroy_marks(struct list_head *to_free); +/* Find mark belonging to given group in the list of marks */ +extern struct fsnotify_mark *fsnotify_find_mark(struct hlist_head *head, + struct fsnotify_group *group); +/* run the list of all marks associated with inode and flag them to be freed */ +extern void fsnotify_clear_marks_by_inode(struct inode *inode); +/* run the list of all marks associated with vfsmount and flag them to be freed */ +extern void fsnotify_clear_marks_by_mount(struct vfsmount *mnt); +/* + * update the dentry->d_flags of all of inode's children to indicate if inode cares + * about events that happen to its children. + */ +extern void __fsnotify_update_child_dentry_flags(struct inode *inode); + +/* allocate and destroy and event holder to attach events to notification/access queues */ +extern struct fsnotify_event_holder *fsnotify_alloc_event_holder(void); +extern void fsnotify_destroy_event_holder(struct fsnotify_event_holder *holder); + +#endif /* __FS_NOTIFY_FSNOTIFY_H_ */ diff --git a/kernel/fs/notify/group.c b/kernel/fs/notify/group.c new file mode 100644 index 000000000..d16b62cb2 --- /dev/null +++ b/kernel/fs/notify/group.c @@ -0,0 +1,118 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/srcu.h> +#include <linux/rculist.h> +#include <linux/wait.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +#include <linux/atomic.h> + +/* + * Final freeing of a group + */ +static void fsnotify_final_destroy_group(struct fsnotify_group *group) +{ + if (group->ops->free_group_priv) + group->ops->free_group_priv(group); + + kfree(group); +} + +/* + * Trying to get rid of a group. Remove all marks, flush all events and release + * the group reference. + * Note that another thread calling fsnotify_clear_marks_by_group() may still + * hold a ref to the group. + */ +void fsnotify_destroy_group(struct fsnotify_group *group) +{ + /* clear all inode marks for this group */ + fsnotify_clear_marks_by_group(group); + + synchronize_srcu(&fsnotify_mark_srcu); + + /* clear the notification queue of all events */ + fsnotify_flush_notify(group); + + /* + * Destroy overflow event (we cannot use fsnotify_destroy_event() as + * that deliberately ignores overflow events. + */ + if (group->overflow_event) + group->ops->free_event(group->overflow_event); + + fsnotify_put_group(group); +} + +/* + * Get reference to a group. + */ +void fsnotify_get_group(struct fsnotify_group *group) +{ + atomic_inc(&group->refcnt); +} + +/* + * Drop a reference to a group. Free it if it's through. + */ +void fsnotify_put_group(struct fsnotify_group *group) +{ + if (atomic_dec_and_test(&group->refcnt)) + fsnotify_final_destroy_group(group); +} + +/* + * Create a new fsnotify_group and hold a reference for the group returned. + */ +struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) +{ + struct fsnotify_group *group; + + group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); + if (!group) + return ERR_PTR(-ENOMEM); + + /* set to 0 when there a no external references to this group */ + atomic_set(&group->refcnt, 1); + atomic_set(&group->num_marks, 0); + + mutex_init(&group->notification_mutex); + INIT_LIST_HEAD(&group->notification_list); + init_waitqueue_head(&group->notification_waitq); + group->max_events = UINT_MAX; + + mutex_init(&group->mark_mutex); + INIT_LIST_HEAD(&group->marks_list); + + group->ops = ops; + + return group; +} + +int fsnotify_fasync(int fd, struct file *file, int on) +{ + struct fsnotify_group *group = file->private_data; + + return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO; +} diff --git a/kernel/fs/notify/inode_mark.c b/kernel/fs/notify/inode_mark.c new file mode 100644 index 000000000..3daf513ee --- /dev/null +++ b/kernel/fs/notify/inode_mark.c @@ -0,0 +1,247 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> + +#include <linux/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +#include "../internal.h" + +/* + * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types + * any notifier is interested in hearing for this inode. + */ +void fsnotify_recalc_inode_mask(struct inode *inode) +{ + spin_lock(&inode->i_lock); + inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks); + spin_unlock(&inode->i_lock); + + __fsnotify_update_child_dentry_flags(inode); +} + +void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark) +{ + struct inode *inode = mark->inode; + + BUG_ON(!mutex_is_locked(&mark->group->mark_mutex)); + assert_spin_locked(&mark->lock); + + spin_lock(&inode->i_lock); + + hlist_del_init_rcu(&mark->obj_list); + mark->inode = NULL; + + /* + * this mark is now off the inode->i_fsnotify_marks list and we + * hold the inode->i_lock, so this is the perfect time to update the + * inode->i_fsnotify_mask + */ + inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks); + spin_unlock(&inode->i_lock); +} + +/* + * Given an inode, destroy all of the marks associated with that inode. + */ +void fsnotify_clear_marks_by_inode(struct inode *inode) +{ + struct fsnotify_mark *mark; + struct hlist_node *n; + LIST_HEAD(free_list); + + spin_lock(&inode->i_lock); + hlist_for_each_entry_safe(mark, n, &inode->i_fsnotify_marks, obj_list) { + list_add(&mark->free_list, &free_list); + hlist_del_init_rcu(&mark->obj_list); + fsnotify_get_mark(mark); + } + spin_unlock(&inode->i_lock); + + fsnotify_destroy_marks(&free_list); +} + +/* + * Given a group clear all of the inode marks associated with that group. + */ +void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group) +{ + fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE); +} + +/* + * given a group and inode, find the mark associated with that combination. + * if found take a reference to that mark and return it, else return NULL + */ +struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, + struct inode *inode) +{ + struct fsnotify_mark *mark; + + spin_lock(&inode->i_lock); + mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group); + spin_unlock(&inode->i_lock); + + return mark; +} + +/* + * If we are setting a mark mask on an inode mark we should pin the inode + * in memory. + */ +void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark, + __u32 mask) +{ + struct inode *inode; + + assert_spin_locked(&mark->lock); + + if (mask && + mark->inode && + !(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) { + mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED; + inode = igrab(mark->inode); + /* + * we shouldn't be able to get here if the inode wasn't + * already safely held in memory. But bug in case it + * ever is wrong. + */ + BUG_ON(!inode); + } +} + +/* + * Attach an initialized mark to a given inode. + * These marks may be used for the fsnotify backend to determine which + * event types should be delivered to which group and for which inodes. These + * marks are ordered according to priority, highest number first, and then by + * the group's location in memory. + */ +int fsnotify_add_inode_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group, struct inode *inode, + int allow_dups) +{ + int ret; + + mark->flags |= FSNOTIFY_MARK_FLAG_INODE; + + BUG_ON(!mutex_is_locked(&group->mark_mutex)); + assert_spin_locked(&mark->lock); + + spin_lock(&inode->i_lock); + mark->inode = inode; + ret = fsnotify_add_mark_list(&inode->i_fsnotify_marks, mark, + allow_dups); + inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks); + spin_unlock(&inode->i_lock); + + return ret; +} + +/** + * fsnotify_unmount_inodes - an sb is unmounting. handle any watched inodes. + * @list: list of inodes being unmounted (sb->s_inodes) + * + * Called during unmount with no locks held, so needs to be safe against + * concurrent modifiers. We temporarily drop inode_sb_list_lock and CAN block. + */ +void fsnotify_unmount_inodes(struct list_head *list) +{ + struct inode *inode, *next_i, *need_iput = NULL; + + spin_lock(&inode_sb_list_lock); + list_for_each_entry_safe(inode, next_i, list, i_sb_list) { + struct inode *need_iput_tmp; + + /* + * We cannot __iget() an inode in state I_FREEING, + * I_WILL_FREE, or I_NEW which is fine because by that point + * the inode cannot have any associated watches. + */ + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { + spin_unlock(&inode->i_lock); + continue; + } + + /* + * If i_count is zero, the inode cannot have any watches and + * doing an __iget/iput with MS_ACTIVE clear would actually + * evict all inodes with zero i_count from icache which is + * unnecessarily violent and may in fact be illegal to do. + */ + if (!atomic_read(&inode->i_count)) { + spin_unlock(&inode->i_lock); + continue; + } + + need_iput_tmp = need_iput; + need_iput = NULL; + + /* In case fsnotify_inode_delete() drops a reference. */ + if (inode != need_iput_tmp) + __iget(inode); + else + need_iput_tmp = NULL; + spin_unlock(&inode->i_lock); + + /* In case the dropping of a reference would nuke next_i. */ + while (&next_i->i_sb_list != list) { + spin_lock(&next_i->i_lock); + if (!(next_i->i_state & (I_FREEING | I_WILL_FREE)) && + atomic_read(&next_i->i_count)) { + __iget(next_i); + need_iput = next_i; + spin_unlock(&next_i->i_lock); + break; + } + spin_unlock(&next_i->i_lock); + next_i = list_entry(next_i->i_sb_list.next, + struct inode, i_sb_list); + } + + /* + * We can safely drop inode_sb_list_lock here because either + * we actually hold references on both inode and next_i or + * end of list. Also no new inodes will be added since the + * umount has begun. + */ + spin_unlock(&inode_sb_list_lock); + + if (need_iput_tmp) + iput(need_iput_tmp); + + /* for each watch, send FS_UNMOUNT and then remove it */ + fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0); + + fsnotify_inode_delete(inode); + + iput(inode); + + spin_lock(&inode_sb_list_lock); + } + spin_unlock(&inode_sb_list_lock); +} diff --git a/kernel/fs/notify/inotify/Kconfig b/kernel/fs/notify/inotify/Kconfig new file mode 100644 index 000000000..b981fc0c8 --- /dev/null +++ b/kernel/fs/notify/inotify/Kconfig @@ -0,0 +1,17 @@ +config INOTIFY_USER + bool "Inotify support for userspace" + select ANON_INODES + select FSNOTIFY + default y + ---help--- + Say Y here to enable inotify support for userspace, including the + associated system calls. Inotify allows monitoring of both files and + directories via a single open fd. Events are read from the file + descriptor, which is also select()- and poll()-able. + Inotify fixes numerous shortcomings in dnotify and introduces several + new features including multiple file events, one-shot support, and + unmount notification. + + For more information, see <file:Documentation/filesystems/inotify.txt> + + If unsure, say Y. diff --git a/kernel/fs/notify/inotify/Makefile b/kernel/fs/notify/inotify/Makefile new file mode 100644 index 000000000..a380dabe0 --- /dev/null +++ b/kernel/fs/notify/inotify/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_INOTIFY_USER) += inotify_fsnotify.o inotify_user.o diff --git a/kernel/fs/notify/inotify/inotify.h b/kernel/fs/notify/inotify/inotify.h new file mode 100644 index 000000000..ed855ef6f --- /dev/null +++ b/kernel/fs/notify/inotify/inotify.h @@ -0,0 +1,32 @@ +#include <linux/fsnotify_backend.h> +#include <linux/inotify.h> +#include <linux/slab.h> /* struct kmem_cache */ + +struct inotify_event_info { + struct fsnotify_event fse; + int wd; + u32 sync_cookie; + int name_len; + char name[]; +}; + +struct inotify_inode_mark { + struct fsnotify_mark fsn_mark; + int wd; +}; + +static inline struct inotify_event_info *INOTIFY_E(struct fsnotify_event *fse) +{ + return container_of(fse, struct inotify_event_info, fse); +} + +extern void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, + struct fsnotify_group *group); +extern int inotify_handle_event(struct fsnotify_group *group, + struct inode *inode, + struct fsnotify_mark *inode_mark, + struct fsnotify_mark *vfsmount_mark, + u32 mask, void *data, int data_type, + const unsigned char *file_name, u32 cookie); + +extern const struct fsnotify_ops inotify_fsnotify_ops; diff --git a/kernel/fs/notify/inotify/inotify_fsnotify.c b/kernel/fs/notify/inotify/inotify_fsnotify.c new file mode 100644 index 000000000..2cd900c2c --- /dev/null +++ b/kernel/fs/notify/inotify/inotify_fsnotify.c @@ -0,0 +1,184 @@ +/* + * fs/inotify_user.c - inotify support for userspace + * + * Authors: + * John McCutchan <ttb@tentacle.dhs.org> + * Robert Love <rml@novell.com> + * + * Copyright (C) 2005 John McCutchan + * Copyright 2006 Hewlett-Packard Development Company, L.P. + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * inotify was largely rewriten to make use of the fsnotify infrastructure + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include <linux/dcache.h> /* d_unlinked */ +#include <linux/fs.h> /* struct inode */ +#include <linux/fsnotify_backend.h> +#include <linux/inotify.h> +#include <linux/path.h> /* struct path */ +#include <linux/slab.h> /* kmem_* */ +#include <linux/types.h> +#include <linux/sched.h> + +#include "inotify.h" + +/* + * Check if 2 events contain the same information. + */ +static bool event_compare(struct fsnotify_event *old_fsn, + struct fsnotify_event *new_fsn) +{ + struct inotify_event_info *old, *new; + + if (old_fsn->mask & FS_IN_IGNORED) + return false; + old = INOTIFY_E(old_fsn); + new = INOTIFY_E(new_fsn); + if ((old_fsn->mask == new_fsn->mask) && + (old_fsn->inode == new_fsn->inode) && + (old->name_len == new->name_len) && + (!old->name_len || !strcmp(old->name, new->name))) + return true; + return false; +} + +static int inotify_merge(struct list_head *list, + struct fsnotify_event *event) +{ + struct fsnotify_event *last_event; + + last_event = list_entry(list->prev, struct fsnotify_event, list); + return event_compare(last_event, event); +} + +int inotify_handle_event(struct fsnotify_group *group, + struct inode *inode, + struct fsnotify_mark *inode_mark, + struct fsnotify_mark *vfsmount_mark, + u32 mask, void *data, int data_type, + const unsigned char *file_name, u32 cookie) +{ + struct inotify_inode_mark *i_mark; + struct inotify_event_info *event; + struct fsnotify_event *fsn_event; + int ret; + int len = 0; + int alloc_len = sizeof(struct inotify_event_info); + + BUG_ON(vfsmount_mark); + + if ((inode_mark->mask & FS_EXCL_UNLINK) && + (data_type == FSNOTIFY_EVENT_PATH)) { + struct path *path = data; + + if (d_unlinked(path->dentry)) + return 0; + } + if (file_name) { + len = strlen(file_name); + alloc_len += len + 1; + } + + pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode, + mask); + + i_mark = container_of(inode_mark, struct inotify_inode_mark, + fsn_mark); + + event = kmalloc(alloc_len, GFP_KERNEL); + if (unlikely(!event)) + return -ENOMEM; + + fsn_event = &event->fse; + fsnotify_init_event(fsn_event, inode, mask); + event->wd = i_mark->wd; + event->sync_cookie = cookie; + event->name_len = len; + if (len) + strcpy(event->name, file_name); + + ret = fsnotify_add_event(group, fsn_event, inotify_merge); + if (ret) { + /* Our event wasn't used in the end. Free it. */ + fsnotify_destroy_event(group, fsn_event); + } + + if (inode_mark->mask & IN_ONESHOT) + fsnotify_destroy_mark(inode_mark, group); + + return 0; +} + +static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group) +{ + inotify_ignored_and_remove_idr(fsn_mark, group); +} + +/* + * This is NEVER supposed to be called. Inotify marks should either have been + * removed from the idr when the watch was removed or in the + * fsnotify_destroy_mark_by_group() call when the inotify instance was being + * torn down. This is only called if the idr is about to be freed but there + * are still marks in it. + */ +static int idr_callback(int id, void *p, void *data) +{ + struct fsnotify_mark *fsn_mark; + struct inotify_inode_mark *i_mark; + static bool warned = false; + + if (warned) + return 0; + + warned = true; + fsn_mark = p; + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + + WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in " + "idr. Probably leaking memory\n", id, p, data); + + /* + * I'm taking the liberty of assuming that the mark in question is a + * valid address and I'm dereferencing it. This might help to figure + * out why we got here and the panic is no worse than the original + * BUG() that was here. + */ + if (fsn_mark) + printk(KERN_WARNING "fsn_mark->group=%p inode=%p wd=%d\n", + fsn_mark->group, fsn_mark->inode, i_mark->wd); + return 0; +} + +static void inotify_free_group_priv(struct fsnotify_group *group) +{ + /* ideally the idr is empty and we won't hit the BUG in the callback */ + idr_for_each(&group->inotify_data.idr, idr_callback, group); + idr_destroy(&group->inotify_data.idr); + if (group->inotify_data.user) { + atomic_dec(&group->inotify_data.user->inotify_devs); + free_uid(group->inotify_data.user); + } +} + +static void inotify_free_event(struct fsnotify_event *fsn_event) +{ + kfree(INOTIFY_E(fsn_event)); +} + +const struct fsnotify_ops inotify_fsnotify_ops = { + .handle_event = inotify_handle_event, + .free_group_priv = inotify_free_group_priv, + .free_event = inotify_free_event, + .freeing_mark = inotify_freeing_mark, +}; diff --git a/kernel/fs/notify/inotify/inotify_user.c b/kernel/fs/notify/inotify/inotify_user.c new file mode 100644 index 000000000..450648697 --- /dev/null +++ b/kernel/fs/notify/inotify/inotify_user.c @@ -0,0 +1,815 @@ +/* + * fs/inotify_user.c - inotify support for userspace + * + * Authors: + * John McCutchan <ttb@tentacle.dhs.org> + * Robert Love <rml@novell.com> + * + * Copyright (C) 2005 John McCutchan + * Copyright 2006 Hewlett-Packard Development Company, L.P. + * + * Copyright (C) 2009 Eric Paris <Red Hat Inc> + * inotify was largely rewriten to make use of the fsnotify infrastructure + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include <linux/file.h> +#include <linux/fs.h> /* struct inode */ +#include <linux/fsnotify_backend.h> +#include <linux/idr.h> +#include <linux/init.h> /* module_init */ +#include <linux/inotify.h> +#include <linux/kernel.h> /* roundup() */ +#include <linux/namei.h> /* LOOKUP_FOLLOW */ +#include <linux/sched.h> /* struct user */ +#include <linux/slab.h> /* struct kmem_cache */ +#include <linux/syscalls.h> +#include <linux/types.h> +#include <linux/anon_inodes.h> +#include <linux/uaccess.h> +#include <linux/poll.h> +#include <linux/wait.h> + +#include "inotify.h" +#include "../fdinfo.h" + +#include <asm/ioctls.h> + +/* these are configurable via /proc/sys/fs/inotify/ */ +static int inotify_max_user_instances __read_mostly; +static int inotify_max_queued_events __read_mostly; +static int inotify_max_user_watches __read_mostly; + +static struct kmem_cache *inotify_inode_mark_cachep __read_mostly; + +#ifdef CONFIG_SYSCTL + +#include <linux/sysctl.h> + +static int zero; + +struct ctl_table inotify_table[] = { + { + .procname = "max_user_instances", + .data = &inotify_max_user_instances, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + }, + { + .procname = "max_user_watches", + .data = &inotify_max_user_watches, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + }, + { + .procname = "max_queued_events", + .data = &inotify_max_queued_events, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero + }, + { } +}; +#endif /* CONFIG_SYSCTL */ + +static inline __u32 inotify_arg_to_mask(u32 arg) +{ + __u32 mask; + + /* + * everything should accept their own ignored, cares about children, + * and should receive events when the inode is unmounted + */ + mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT); + + /* mask off the flags used to open the fd */ + mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK)); + + return mask; +} + +static inline u32 inotify_mask_to_arg(__u32 mask) +{ + return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | + IN_Q_OVERFLOW); +} + +/* intofiy userspace file descriptor functions */ +static unsigned int inotify_poll(struct file *file, poll_table *wait) +{ + struct fsnotify_group *group = file->private_data; + int ret = 0; + + poll_wait(file, &group->notification_waitq, wait); + mutex_lock(&group->notification_mutex); + if (!fsnotify_notify_queue_is_empty(group)) + ret = POLLIN | POLLRDNORM; + mutex_unlock(&group->notification_mutex); + + return ret; +} + +static int round_event_name_len(struct fsnotify_event *fsn_event) +{ + struct inotify_event_info *event; + + event = INOTIFY_E(fsn_event); + if (!event->name_len) + return 0; + return roundup(event->name_len + 1, sizeof(struct inotify_event)); +} + +/* + * Get an inotify_kernel_event if one exists and is small + * enough to fit in "count". Return an error pointer if + * not large enough. + * + * Called with the group->notification_mutex held. + */ +static struct fsnotify_event *get_one_event(struct fsnotify_group *group, + size_t count) +{ + size_t event_size = sizeof(struct inotify_event); + struct fsnotify_event *event; + + if (fsnotify_notify_queue_is_empty(group)) + return NULL; + + event = fsnotify_peek_first_event(group); + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + event_size += round_event_name_len(event); + if (event_size > count) + return ERR_PTR(-EINVAL); + + /* held the notification_mutex the whole time, so this is the + * same event we peeked above */ + fsnotify_remove_first_event(group); + + return event; +} + +/* + * Copy an event to user space, returning how much we copied. + * + * We already checked that the event size is smaller than the + * buffer we had in "get_one_event()" above. + */ +static ssize_t copy_event_to_user(struct fsnotify_group *group, + struct fsnotify_event *fsn_event, + char __user *buf) +{ + struct inotify_event inotify_event; + struct inotify_event_info *event; + size_t event_size = sizeof(struct inotify_event); + size_t name_len; + size_t pad_name_len; + + pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event); + + event = INOTIFY_E(fsn_event); + name_len = event->name_len; + /* + * round up name length so it is a multiple of event_size + * plus an extra byte for the terminating '\0'. + */ + pad_name_len = round_event_name_len(fsn_event); + inotify_event.len = pad_name_len; + inotify_event.mask = inotify_mask_to_arg(fsn_event->mask); + inotify_event.wd = event->wd; + inotify_event.cookie = event->sync_cookie; + + /* send the main event */ + if (copy_to_user(buf, &inotify_event, event_size)) + return -EFAULT; + + buf += event_size; + + /* + * fsnotify only stores the pathname, so here we have to send the pathname + * and then pad that pathname out to a multiple of sizeof(inotify_event) + * with zeros. + */ + if (pad_name_len) { + /* copy the path name */ + if (copy_to_user(buf, event->name, name_len)) + return -EFAULT; + buf += name_len; + + /* fill userspace with 0's */ + if (clear_user(buf, pad_name_len - name_len)) + return -EFAULT; + event_size += pad_name_len; + } + + return event_size; +} + +static ssize_t inotify_read(struct file *file, char __user *buf, + size_t count, loff_t *pos) +{ + struct fsnotify_group *group; + struct fsnotify_event *kevent; + char __user *start; + int ret; + DEFINE_WAIT_FUNC(wait, woken_wake_function); + + start = buf; + group = file->private_data; + + add_wait_queue(&group->notification_waitq, &wait); + while (1) { + mutex_lock(&group->notification_mutex); + kevent = get_one_event(group, count); + mutex_unlock(&group->notification_mutex); + + pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent); + + if (kevent) { + ret = PTR_ERR(kevent); + if (IS_ERR(kevent)) + break; + ret = copy_event_to_user(group, kevent, buf); + fsnotify_destroy_event(group, kevent); + if (ret < 0) + break; + buf += ret; + count -= ret; + continue; + } + + ret = -EAGAIN; + if (file->f_flags & O_NONBLOCK) + break; + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + + if (start != buf) + break; + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + } + remove_wait_queue(&group->notification_waitq, &wait); + + if (start != buf && ret != -EFAULT) + ret = buf - start; + return ret; +} + +static int inotify_release(struct inode *ignored, struct file *file) +{ + struct fsnotify_group *group = file->private_data; + + pr_debug("%s: group=%p\n", __func__, group); + + /* free this group, matching get was inotify_init->fsnotify_obtain_group */ + fsnotify_destroy_group(group); + + return 0; +} + +static long inotify_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct fsnotify_group *group; + struct fsnotify_event *fsn_event; + void __user *p; + int ret = -ENOTTY; + size_t send_len = 0; + + group = file->private_data; + p = (void __user *) arg; + + pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd); + + switch (cmd) { + case FIONREAD: + mutex_lock(&group->notification_mutex); + list_for_each_entry(fsn_event, &group->notification_list, + list) { + send_len += sizeof(struct inotify_event); + send_len += round_event_name_len(fsn_event); + } + mutex_unlock(&group->notification_mutex); + ret = put_user(send_len, (int __user *) p); + break; + } + + return ret; +} + +static const struct file_operations inotify_fops = { + .show_fdinfo = inotify_show_fdinfo, + .poll = inotify_poll, + .read = inotify_read, + .fasync = fsnotify_fasync, + .release = inotify_release, + .unlocked_ioctl = inotify_ioctl, + .compat_ioctl = inotify_ioctl, + .llseek = noop_llseek, +}; + + +/* + * find_inode - resolve a user-given path to a specific inode + */ +static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags) +{ + int error; + + error = user_path_at(AT_FDCWD, dirname, flags, path); + if (error) + return error; + /* you can only watch an inode if you have read permissions on it */ + error = inode_permission(path->dentry->d_inode, MAY_READ); + if (error) + path_put(path); + return error; +} + +static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock, + struct inotify_inode_mark *i_mark) +{ + int ret; + + idr_preload(GFP_KERNEL); + spin_lock(idr_lock); + + ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT); + if (ret >= 0) { + /* we added the mark to the idr, take a reference */ + i_mark->wd = ret; + fsnotify_get_mark(&i_mark->fsn_mark); + } + + spin_unlock(idr_lock); + idr_preload_end(); + return ret < 0 ? ret : 0; +} + +static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group, + int wd) +{ + struct idr *idr = &group->inotify_data.idr; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + struct inotify_inode_mark *i_mark; + + assert_spin_locked(idr_lock); + + i_mark = idr_find(idr, wd); + if (i_mark) { + struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark; + + fsnotify_get_mark(fsn_mark); + /* One ref for being in the idr, one ref we just took */ + BUG_ON(atomic_read(&fsn_mark->refcnt) < 2); + } + + return i_mark; +} + +static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group, + int wd) +{ + struct inotify_inode_mark *i_mark; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + + spin_lock(idr_lock); + i_mark = inotify_idr_find_locked(group, wd); + spin_unlock(idr_lock); + + return i_mark; +} + +static void do_inotify_remove_from_idr(struct fsnotify_group *group, + struct inotify_inode_mark *i_mark) +{ + struct idr *idr = &group->inotify_data.idr; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + int wd = i_mark->wd; + + assert_spin_locked(idr_lock); + + idr_remove(idr, wd); + + /* removed from the idr, drop that ref */ + fsnotify_put_mark(&i_mark->fsn_mark); +} + +/* + * Remove the mark from the idr (if present) and drop the reference + * on the mark because it was in the idr. + */ +static void inotify_remove_from_idr(struct fsnotify_group *group, + struct inotify_inode_mark *i_mark) +{ + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + struct inotify_inode_mark *found_i_mark = NULL; + int wd; + + spin_lock(idr_lock); + wd = i_mark->wd; + + /* + * does this i_mark think it is in the idr? we shouldn't get called + * if it wasn't.... + */ + if (wd == -1) { + WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" + " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, + i_mark->fsn_mark.group, i_mark->fsn_mark.inode); + goto out; + } + + /* Lets look in the idr to see if we find it */ + found_i_mark = inotify_idr_find_locked(group, wd); + if (unlikely(!found_i_mark)) { + WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" + " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, + i_mark->fsn_mark.group, i_mark->fsn_mark.inode); + goto out; + } + + /* + * We found an mark in the idr at the right wd, but it's + * not the mark we were told to remove. eparis seriously + * fucked up somewhere. + */ + if (unlikely(found_i_mark != i_mark)) { + WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p " + "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d " + "found_i_mark->group=%p found_i_mark->inode=%p\n", + __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group, + i_mark->fsn_mark.inode, found_i_mark, found_i_mark->wd, + found_i_mark->fsn_mark.group, + found_i_mark->fsn_mark.inode); + goto out; + } + + /* + * One ref for being in the idr + * one ref held by the caller trying to kill us + * one ref grabbed by inotify_idr_find + */ + if (unlikely(atomic_read(&i_mark->fsn_mark.refcnt) < 3)) { + printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" + " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, + i_mark->fsn_mark.group, i_mark->fsn_mark.inode); + /* we can't really recover with bad ref cnting.. */ + BUG(); + } + + do_inotify_remove_from_idr(group, i_mark); +out: + /* match the ref taken by inotify_idr_find_locked() */ + if (found_i_mark) + fsnotify_put_mark(&found_i_mark->fsn_mark); + i_mark->wd = -1; + spin_unlock(idr_lock); +} + +/* + * Send IN_IGNORED for this wd, remove this wd from the idr. + */ +void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, + struct fsnotify_group *group) +{ + struct inotify_inode_mark *i_mark; + + /* Queue ignore event for the watch */ + inotify_handle_event(group, NULL, fsn_mark, NULL, FS_IN_IGNORED, + NULL, FSNOTIFY_EVENT_NONE, NULL, 0); + + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + /* remove this mark from the idr */ + inotify_remove_from_idr(group, i_mark); + + atomic_dec(&group->inotify_data.user->inotify_watches); +} + +/* ding dong the mark is dead */ +static void inotify_free_mark(struct fsnotify_mark *fsn_mark) +{ + struct inotify_inode_mark *i_mark; + + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + + kmem_cache_free(inotify_inode_mark_cachep, i_mark); +} + +static int inotify_update_existing_watch(struct fsnotify_group *group, + struct inode *inode, + u32 arg) +{ + struct fsnotify_mark *fsn_mark; + struct inotify_inode_mark *i_mark; + __u32 old_mask, new_mask; + __u32 mask; + int add = (arg & IN_MASK_ADD); + int ret; + + mask = inotify_arg_to_mask(arg); + + fsn_mark = fsnotify_find_inode_mark(group, inode); + if (!fsn_mark) + return -ENOENT; + + i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); + + spin_lock(&fsn_mark->lock); + + old_mask = fsn_mark->mask; + if (add) + fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask)); + else + fsnotify_set_mark_mask_locked(fsn_mark, mask); + new_mask = fsn_mark->mask; + + spin_unlock(&fsn_mark->lock); + + if (old_mask != new_mask) { + /* more bits in old than in new? */ + int dropped = (old_mask & ~new_mask); + /* more bits in this fsn_mark than the inode's mask? */ + int do_inode = (new_mask & ~inode->i_fsnotify_mask); + + /* update the inode with this new fsn_mark */ + if (dropped || do_inode) + fsnotify_recalc_inode_mask(inode); + + } + + /* return the wd */ + ret = i_mark->wd; + + /* match the get from fsnotify_find_mark() */ + fsnotify_put_mark(fsn_mark); + + return ret; +} + +static int inotify_new_watch(struct fsnotify_group *group, + struct inode *inode, + u32 arg) +{ + struct inotify_inode_mark *tmp_i_mark; + __u32 mask; + int ret; + struct idr *idr = &group->inotify_data.idr; + spinlock_t *idr_lock = &group->inotify_data.idr_lock; + + mask = inotify_arg_to_mask(arg); + + tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); + if (unlikely(!tmp_i_mark)) + return -ENOMEM; + + fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark); + tmp_i_mark->fsn_mark.mask = mask; + tmp_i_mark->wd = -1; + + ret = -ENOSPC; + if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) + goto out_err; + + ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark); + if (ret) + goto out_err; + + /* we are on the idr, now get on the inode */ + ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, group, inode, + NULL, 0); + if (ret) { + /* we failed to get on the inode, get off the idr */ + inotify_remove_from_idr(group, tmp_i_mark); + goto out_err; + } + + /* increment the number of watches the user has */ + atomic_inc(&group->inotify_data.user->inotify_watches); + + /* return the watch descriptor for this new mark */ + ret = tmp_i_mark->wd; + +out_err: + /* match the ref from fsnotify_init_mark() */ + fsnotify_put_mark(&tmp_i_mark->fsn_mark); + + return ret; +} + +static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) +{ + int ret = 0; + + mutex_lock(&group->mark_mutex); + /* try to update and existing watch with the new arg */ + ret = inotify_update_existing_watch(group, inode, arg); + /* no mark present, try to add a new one */ + if (ret == -ENOENT) + ret = inotify_new_watch(group, inode, arg); + mutex_unlock(&group->mark_mutex); + + return ret; +} + +static struct fsnotify_group *inotify_new_group(unsigned int max_events) +{ + struct fsnotify_group *group; + struct inotify_event_info *oevent; + + group = fsnotify_alloc_group(&inotify_fsnotify_ops); + if (IS_ERR(group)) + return group; + + oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL); + if (unlikely(!oevent)) { + fsnotify_destroy_group(group); + return ERR_PTR(-ENOMEM); + } + group->overflow_event = &oevent->fse; + fsnotify_init_event(group->overflow_event, NULL, FS_Q_OVERFLOW); + oevent->wd = -1; + oevent->sync_cookie = 0; + oevent->name_len = 0; + + group->max_events = max_events; + + spin_lock_init(&group->inotify_data.idr_lock); + idr_init(&group->inotify_data.idr); + group->inotify_data.user = get_current_user(); + + if (atomic_inc_return(&group->inotify_data.user->inotify_devs) > + inotify_max_user_instances) { + fsnotify_destroy_group(group); + return ERR_PTR(-EMFILE); + } + + return group; +} + + +/* inotify syscalls */ +SYSCALL_DEFINE1(inotify_init1, int, flags) +{ + struct fsnotify_group *group; + int ret; + + /* Check the IN_* constants for consistency. */ + BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); + BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); + + if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) + return -EINVAL; + + /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ + group = inotify_new_group(inotify_max_queued_events); + if (IS_ERR(group)) + return PTR_ERR(group); + + ret = anon_inode_getfd("inotify", &inotify_fops, group, + O_RDONLY | flags); + if (ret < 0) + fsnotify_destroy_group(group); + + return ret; +} + +SYSCALL_DEFINE0(inotify_init) +{ + return sys_inotify_init1(0); +} + +SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, + u32, mask) +{ + struct fsnotify_group *group; + struct inode *inode; + struct path path; + struct fd f; + int ret; + unsigned flags = 0; + + /* don't allow invalid bits: we don't want flags set */ + if (unlikely(!(mask & ALL_INOTIFY_BITS))) + return -EINVAL; + + f = fdget(fd); + if (unlikely(!f.file)) + return -EBADF; + + /* verify that this is indeed an inotify instance */ + if (unlikely(f.file->f_op != &inotify_fops)) { + ret = -EINVAL; + goto fput_and_out; + } + + if (!(mask & IN_DONT_FOLLOW)) + flags |= LOOKUP_FOLLOW; + if (mask & IN_ONLYDIR) + flags |= LOOKUP_DIRECTORY; + + ret = inotify_find_inode(pathname, &path, flags); + if (ret) + goto fput_and_out; + + /* inode held in place by reference to path; group by fget on fd */ + inode = path.dentry->d_inode; + group = f.file->private_data; + + /* create/update an inode mark */ + ret = inotify_update_watch(group, inode, mask); + path_put(&path); +fput_and_out: + fdput(f); + return ret; +} + +SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) +{ + struct fsnotify_group *group; + struct inotify_inode_mark *i_mark; + struct fd f; + int ret = 0; + + f = fdget(fd); + if (unlikely(!f.file)) + return -EBADF; + + /* verify that this is indeed an inotify instance */ + ret = -EINVAL; + if (unlikely(f.file->f_op != &inotify_fops)) + goto out; + + group = f.file->private_data; + + ret = -EINVAL; + i_mark = inotify_idr_find(group, wd); + if (unlikely(!i_mark)) + goto out; + + ret = 0; + + fsnotify_destroy_mark(&i_mark->fsn_mark, group); + + /* match ref taken by inotify_idr_find */ + fsnotify_put_mark(&i_mark->fsn_mark); + +out: + fdput(f); + return ret; +} + +/* + * inotify_user_setup - Our initialization function. Note that we cannot return + * error because we have compiled-in VFS hooks. So an (unlikely) failure here + * must result in panic(). + */ +static int __init inotify_user_setup(void) +{ + BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); + BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); + BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); + BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE); + BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); + BUILD_BUG_ON(IN_OPEN != FS_OPEN); + BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM); + BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO); + BUILD_BUG_ON(IN_CREATE != FS_CREATE); + BUILD_BUG_ON(IN_DELETE != FS_DELETE); + BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF); + BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF); + BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT); + BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW); + BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED); + BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK); + BUILD_BUG_ON(IN_ISDIR != FS_ISDIR); + BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT); + + BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21); + + inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC); + + inotify_max_queued_events = 16384; + inotify_max_user_instances = 128; + inotify_max_user_watches = 8192; + + return 0; +} +module_init(inotify_user_setup); diff --git a/kernel/fs/notify/mark.c b/kernel/fs/notify/mark.c new file mode 100644 index 000000000..92e48c70f --- /dev/null +++ b/kernel/fs/notify/mark.c @@ -0,0 +1,494 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +/* + * fsnotify inode mark locking/lifetime/and refcnting + * + * REFCNT: + * The group->recnt and mark->refcnt tell how many "things" in the kernel + * currently are referencing the objects. Both kind of objects typically will + * live inside the kernel with a refcnt of 2, one for its creation and one for + * the reference a group and a mark hold to each other. + * If you are holding the appropriate locks, you can take a reference and the + * object itself is guaranteed to survive until the reference is dropped. + * + * LOCKING: + * There are 3 locks involved with fsnotify inode marks and they MUST be taken + * in order as follows: + * + * group->mark_mutex + * mark->lock + * inode->i_lock + * + * group->mark_mutex protects the marks_list anchored inside a given group and + * each mark is hooked via the g_list. It also protects the groups private + * data (i.e group limits). + + * mark->lock protects the marks attributes like its masks and flags. + * Furthermore it protects the access to a reference of the group that the mark + * is assigned to as well as the access to a reference of the inode/vfsmount + * that is being watched by the mark. + * + * inode->i_lock protects the i_fsnotify_marks list anchored inside a + * given inode and each mark is hooked via the i_list. (and sorta the + * free_i_list) + * + * + * LIFETIME: + * Inode marks survive between when they are added to an inode and when their + * refcnt==0. + * + * The inode mark can be cleared for a number of different reasons including: + * - The inode is unlinked for the last time. (fsnotify_inode_remove) + * - The inode is being evicted from cache. (fsnotify_inode_delete) + * - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes) + * - Something explicitly requests that it be removed. (fsnotify_destroy_mark) + * - The fsnotify_group associated with the mark is going away and all such marks + * need to be cleaned up. (fsnotify_clear_marks_by_group) + * + * Worst case we are given an inode and need to clean up all the marks on that + * inode. We take i_lock and walk the i_fsnotify_marks safely. For each + * mark on the list we take a reference (so the mark can't disappear under us). + * We remove that mark form the inode's list of marks and we add this mark to a + * private list anchored on the stack using i_free_list; we walk i_free_list + * and before we destroy the mark we make sure that we dont race with a + * concurrent destroy_group by getting a ref to the marks group and taking the + * groups mutex. + + * Very similarly for freeing by group, except we use free_g_list. + * + * This has the very interesting property of being able to run concurrently with + * any (or all) other directions. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/kthread.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/srcu.h> + +#include <linux/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +struct srcu_struct fsnotify_mark_srcu; +static DEFINE_SPINLOCK(destroy_lock); +static LIST_HEAD(destroy_list); +static DECLARE_WAIT_QUEUE_HEAD(destroy_waitq); + +void fsnotify_get_mark(struct fsnotify_mark *mark) +{ + atomic_inc(&mark->refcnt); +} + +void fsnotify_put_mark(struct fsnotify_mark *mark) +{ + if (atomic_dec_and_test(&mark->refcnt)) { + if (mark->group) + fsnotify_put_group(mark->group); + mark->free_mark(mark); + } +} + +/* Calculate mask of events for a list of marks */ +u32 fsnotify_recalc_mask(struct hlist_head *head) +{ + u32 new_mask = 0; + struct fsnotify_mark *mark; + + hlist_for_each_entry(mark, head, obj_list) + new_mask |= mark->mask; + return new_mask; +} + +/* + * Any time a mark is getting freed we end up here. + * The caller had better be holding a reference to this mark so we don't actually + * do the final put under the mark->lock + */ +void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark, + struct fsnotify_group *group) +{ + struct inode *inode = NULL; + + BUG_ON(!mutex_is_locked(&group->mark_mutex)); + + spin_lock(&mark->lock); + + /* something else already called this function on this mark */ + if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) { + spin_unlock(&mark->lock); + return; + } + + mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE; + + if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) { + inode = mark->inode; + fsnotify_destroy_inode_mark(mark); + } else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT) + fsnotify_destroy_vfsmount_mark(mark); + else + BUG(); + + list_del_init(&mark->g_list); + + spin_unlock(&mark->lock); + + if (inode && (mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) + iput(inode); + /* release lock temporarily */ + mutex_unlock(&group->mark_mutex); + + spin_lock(&destroy_lock); + list_add(&mark->g_list, &destroy_list); + spin_unlock(&destroy_lock); + wake_up(&destroy_waitq); + /* + * We don't necessarily have a ref on mark from caller so the above destroy + * may have actually freed it, unless this group provides a 'freeing_mark' + * function which must be holding a reference. + */ + + /* + * Some groups like to know that marks are being freed. This is a + * callback to the group function to let it know that this mark + * is being freed. + */ + if (group->ops->freeing_mark) + group->ops->freeing_mark(mark, group); + + /* + * __fsnotify_update_child_dentry_flags(inode); + * + * I really want to call that, but we can't, we have no idea if the inode + * still exists the second we drop the mark->lock. + * + * The next time an event arrive to this inode from one of it's children + * __fsnotify_parent will see that the inode doesn't care about it's + * children and will update all of these flags then. So really this + * is just a lazy update (and could be a perf win...) + */ + + atomic_dec(&group->num_marks); + + mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); +} + +void fsnotify_destroy_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group) +{ + mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); + fsnotify_destroy_mark_locked(mark, group); + mutex_unlock(&group->mark_mutex); +} + +/* + * Destroy all marks in the given list. The marks must be already detached from + * the original inode / vfsmount. + */ +void fsnotify_destroy_marks(struct list_head *to_free) +{ + struct fsnotify_mark *mark, *lmark; + struct fsnotify_group *group; + + list_for_each_entry_safe(mark, lmark, to_free, free_list) { + spin_lock(&mark->lock); + fsnotify_get_group(mark->group); + group = mark->group; + spin_unlock(&mark->lock); + + fsnotify_destroy_mark(mark, group); + fsnotify_put_mark(mark); + fsnotify_put_group(group); + } +} + +void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask) +{ + assert_spin_locked(&mark->lock); + + mark->mask = mask; + + if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) + fsnotify_set_inode_mark_mask_locked(mark, mask); +} + +void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask) +{ + assert_spin_locked(&mark->lock); + + mark->ignored_mask = mask; +} + +/* + * Sorting function for lists of fsnotify marks. + * + * Fanotify supports different notification classes (reflected as priority of + * notification group). Events shall be passed to notification groups in + * decreasing priority order. To achieve this marks in notification lists for + * inodes and vfsmounts are sorted so that priorities of corresponding groups + * are descending. + * + * Furthermore correct handling of the ignore mask requires processing inode + * and vfsmount marks of each group together. Using the group address as + * further sort criterion provides a unique sorting order and thus we can + * merge inode and vfsmount lists of marks in linear time and find groups + * present in both lists. + * + * A return value of 1 signifies that b has priority over a. + * A return value of 0 signifies that the two marks have to be handled together. + * A return value of -1 signifies that a has priority over b. + */ +int fsnotify_compare_groups(struct fsnotify_group *a, struct fsnotify_group *b) +{ + if (a == b) + return 0; + if (!a) + return 1; + if (!b) + return -1; + if (a->priority < b->priority) + return 1; + if (a->priority > b->priority) + return -1; + if (a < b) + return 1; + return -1; +} + +/* Add mark into proper place in given list of marks */ +int fsnotify_add_mark_list(struct hlist_head *head, struct fsnotify_mark *mark, + int allow_dups) +{ + struct fsnotify_mark *lmark, *last = NULL; + int cmp; + + /* is mark the first mark? */ + if (hlist_empty(head)) { + hlist_add_head_rcu(&mark->obj_list, head); + return 0; + } + + /* should mark be in the middle of the current list? */ + hlist_for_each_entry(lmark, head, obj_list) { + last = lmark; + + if ((lmark->group == mark->group) && !allow_dups) + return -EEXIST; + + cmp = fsnotify_compare_groups(lmark->group, mark->group); + if (cmp >= 0) { + hlist_add_before_rcu(&mark->obj_list, &lmark->obj_list); + return 0; + } + } + + BUG_ON(last == NULL); + /* mark should be the last entry. last is the current last entry */ + hlist_add_behind_rcu(&mark->obj_list, &last->obj_list); + return 0; +} + +/* + * Attach an initialized mark to a given group and fs object. + * These marks may be used for the fsnotify backend to determine which + * event types should be delivered to which group. + */ +int fsnotify_add_mark_locked(struct fsnotify_mark *mark, + struct fsnotify_group *group, struct inode *inode, + struct vfsmount *mnt, int allow_dups) +{ + int ret = 0; + + BUG_ON(inode && mnt); + BUG_ON(!inode && !mnt); + BUG_ON(!mutex_is_locked(&group->mark_mutex)); + + /* + * LOCKING ORDER!!!! + * group->mark_mutex + * mark->lock + * inode->i_lock + */ + spin_lock(&mark->lock); + mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE; + + fsnotify_get_group(group); + mark->group = group; + list_add(&mark->g_list, &group->marks_list); + atomic_inc(&group->num_marks); + fsnotify_get_mark(mark); /* for i_list and g_list */ + + if (inode) { + ret = fsnotify_add_inode_mark(mark, group, inode, allow_dups); + if (ret) + goto err; + } else if (mnt) { + ret = fsnotify_add_vfsmount_mark(mark, group, mnt, allow_dups); + if (ret) + goto err; + } else { + BUG(); + } + + /* this will pin the object if appropriate */ + fsnotify_set_mark_mask_locked(mark, mark->mask); + spin_unlock(&mark->lock); + + if (inode) + __fsnotify_update_child_dentry_flags(inode); + + return ret; +err: + mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE; + list_del_init(&mark->g_list); + fsnotify_put_group(group); + mark->group = NULL; + atomic_dec(&group->num_marks); + + spin_unlock(&mark->lock); + + spin_lock(&destroy_lock); + list_add(&mark->g_list, &destroy_list); + spin_unlock(&destroy_lock); + wake_up(&destroy_waitq); + + return ret; +} + +int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, + struct inode *inode, struct vfsmount *mnt, int allow_dups) +{ + int ret; + mutex_lock(&group->mark_mutex); + ret = fsnotify_add_mark_locked(mark, group, inode, mnt, allow_dups); + mutex_unlock(&group->mark_mutex); + return ret; +} + +/* + * Given a list of marks, find the mark associated with given group. If found + * take a reference to that mark and return it, else return NULL. + */ +struct fsnotify_mark *fsnotify_find_mark(struct hlist_head *head, + struct fsnotify_group *group) +{ + struct fsnotify_mark *mark; + + hlist_for_each_entry(mark, head, obj_list) { + if (mark->group == group) { + fsnotify_get_mark(mark); + return mark; + } + } + return NULL; +} + +/* + * clear any marks in a group in which mark->flags & flags is true + */ +void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, + unsigned int flags) +{ + struct fsnotify_mark *lmark, *mark; + + mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING); + list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) { + if (mark->flags & flags) { + fsnotify_get_mark(mark); + fsnotify_destroy_mark_locked(mark, group); + fsnotify_put_mark(mark); + } + } + mutex_unlock(&group->mark_mutex); +} + +/* + * Given a group, destroy all of the marks associated with that group. + */ +void fsnotify_clear_marks_by_group(struct fsnotify_group *group) +{ + fsnotify_clear_marks_by_group_flags(group, (unsigned int)-1); +} + +void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old) +{ + assert_spin_locked(&old->lock); + new->inode = old->inode; + new->mnt = old->mnt; + if (old->group) + fsnotify_get_group(old->group); + new->group = old->group; + new->mask = old->mask; + new->free_mark = old->free_mark; +} + +/* + * Nothing fancy, just initialize lists and locks and counters. + */ +void fsnotify_init_mark(struct fsnotify_mark *mark, + void (*free_mark)(struct fsnotify_mark *mark)) +{ + memset(mark, 0, sizeof(*mark)); + spin_lock_init(&mark->lock); + atomic_set(&mark->refcnt, 1); + mark->free_mark = free_mark; +} + +static int fsnotify_mark_destroy(void *ignored) +{ + struct fsnotify_mark *mark, *next; + struct list_head private_destroy_list; + + for (;;) { + spin_lock(&destroy_lock); + /* exchange the list head */ + list_replace_init(&destroy_list, &private_destroy_list); + spin_unlock(&destroy_lock); + + synchronize_srcu(&fsnotify_mark_srcu); + + list_for_each_entry_safe(mark, next, &private_destroy_list, g_list) { + list_del_init(&mark->g_list); + fsnotify_put_mark(mark); + } + + wait_event_interruptible(destroy_waitq, !list_empty(&destroy_list)); + } + + return 0; +} + +static int __init fsnotify_mark_init(void) +{ + struct task_struct *thread; + + thread = kthread_run(fsnotify_mark_destroy, NULL, + "fsnotify_mark"); + if (IS_ERR(thread)) + panic("unable to start fsnotify mark destruction thread."); + + return 0; +} +device_initcall(fsnotify_mark_init); diff --git a/kernel/fs/notify/notification.c b/kernel/fs/notify/notification.c new file mode 100644 index 000000000..a95d8e037 --- /dev/null +++ b/kernel/fs/notify/notification.c @@ -0,0 +1,213 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +/* + * Basic idea behind the notification queue: An fsnotify group (like inotify) + * sends the userspace notification about events asynchronously some time after + * the event happened. When inotify gets an event it will need to add that + * event to the group notify queue. Since a single event might need to be on + * multiple group's notification queues we can't add the event directly to each + * queue and instead add a small "event_holder" to each queue. This event_holder + * has a pointer back to the original event. Since the majority of events are + * going to end up on one, and only one, notification queue we embed one + * event_holder into each event. This means we have a single allocation instead + * of always needing two. If the embedded event_holder is already in use by + * another group a new event_holder (from fsnotify_event_holder_cachep) will be + * allocated and used. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mount.h> +#include <linux/mutex.h> +#include <linux/namei.h> +#include <linux/path.h> +#include <linux/slab.h> +#include <linux/spinlock.h> + +#include <linux/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" + +static atomic_t fsnotify_sync_cookie = ATOMIC_INIT(0); + +/** + * fsnotify_get_cookie - return a unique cookie for use in synchronizing events. + * Called from fsnotify_move, which is inlined into filesystem modules. + */ +u32 fsnotify_get_cookie(void) +{ + return atomic_inc_return(&fsnotify_sync_cookie); +} +EXPORT_SYMBOL_GPL(fsnotify_get_cookie); + +/* return true if the notify queue is empty, false otherwise */ +bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group) +{ + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + return list_empty(&group->notification_list) ? true : false; +} + +void fsnotify_destroy_event(struct fsnotify_group *group, + struct fsnotify_event *event) +{ + /* Overflow events are per-group and we don't want to free them */ + if (!event || event->mask == FS_Q_OVERFLOW) + return; + /* If the event is still queued, we have a problem... */ + WARN_ON(!list_empty(&event->list)); + group->ops->free_event(event); +} + +/* + * Add an event to the group notification queue. The group can later pull this + * event off the queue to deal with. The function returns 0 if the event was + * added to the queue, 1 if the event was merged with some other queued event, + * 2 if the queue of events has overflown. + */ +int fsnotify_add_event(struct fsnotify_group *group, + struct fsnotify_event *event, + int (*merge)(struct list_head *, + struct fsnotify_event *)) +{ + int ret = 0; + struct list_head *list = &group->notification_list; + + pr_debug("%s: group=%p event=%p\n", __func__, group, event); + + mutex_lock(&group->notification_mutex); + + if (group->q_len >= group->max_events) { + ret = 2; + /* Queue overflow event only if it isn't already queued */ + if (!list_empty(&group->overflow_event->list)) { + mutex_unlock(&group->notification_mutex); + return ret; + } + event = group->overflow_event; + goto queue; + } + + if (!list_empty(list) && merge) { + ret = merge(list, event); + if (ret) { + mutex_unlock(&group->notification_mutex); + return ret; + } + } + +queue: + group->q_len++; + list_add_tail(&event->list, list); + mutex_unlock(&group->notification_mutex); + + wake_up(&group->notification_waitq); + kill_fasync(&group->fsn_fa, SIGIO, POLL_IN); + return ret; +} + +/* + * Remove @event from group's notification queue. It is the responsibility of + * the caller to destroy the event. + */ +void fsnotify_remove_event(struct fsnotify_group *group, + struct fsnotify_event *event) +{ + mutex_lock(&group->notification_mutex); + if (!list_empty(&event->list)) { + list_del_init(&event->list); + group->q_len--; + } + mutex_unlock(&group->notification_mutex); +} + +/* + * Remove and return the first event from the notification list. It is the + * responsibility of the caller to destroy the obtained event + */ +struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + + pr_debug("%s: group=%p\n", __func__, group); + + event = list_first_entry(&group->notification_list, + struct fsnotify_event, list); + /* + * We need to init list head for the case of overflow event so that + * check in fsnotify_add_event() works + */ + list_del_init(&event->list); + group->q_len--; + + return event; +} + +/* + * This will not remove the event, that must be done with + * fsnotify_remove_first_event() + */ +struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group) +{ + BUG_ON(!mutex_is_locked(&group->notification_mutex)); + + return list_first_entry(&group->notification_list, + struct fsnotify_event, list); +} + +/* + * Called when a group is being torn down to clean up any outstanding + * event notifications. + */ +void fsnotify_flush_notify(struct fsnotify_group *group) +{ + struct fsnotify_event *event; + + mutex_lock(&group->notification_mutex); + while (!fsnotify_notify_queue_is_empty(group)) { + event = fsnotify_remove_first_event(group); + fsnotify_destroy_event(group, event); + } + mutex_unlock(&group->notification_mutex); +} + +/* + * fsnotify_create_event - Allocate a new event which will be sent to each + * group's handle_event function if the group was interested in this + * particular event. + * + * @inode the inode which is supposed to receive the event (sometimes a + * parent of the inode to which the event happened. + * @mask what actually happened. + * @data pointer to the object which was actually affected + * @data_type flag indication if the data is a file, path, inode, nothing... + * @name the filename, if available + */ +void fsnotify_init_event(struct fsnotify_event *event, struct inode *inode, + u32 mask) +{ + INIT_LIST_HEAD(&event->list); + event->inode = inode; + event->mask = mask; +} diff --git a/kernel/fs/notify/vfsmount_mark.c b/kernel/fs/notify/vfsmount_mark.c new file mode 100644 index 000000000..326b148e6 --- /dev/null +++ b/kernel/fs/notify/vfsmount_mark.c @@ -0,0 +1,127 @@ +/* + * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2, or (at your option) + * any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mount.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> + +#include <linux/atomic.h> + +#include <linux/fsnotify_backend.h> +#include "fsnotify.h" +#include "../mount.h" + +void fsnotify_clear_marks_by_mount(struct vfsmount *mnt) +{ + struct fsnotify_mark *mark; + struct hlist_node *n; + struct mount *m = real_mount(mnt); + LIST_HEAD(free_list); + + spin_lock(&mnt->mnt_root->d_lock); + hlist_for_each_entry_safe(mark, n, &m->mnt_fsnotify_marks, obj_list) { + list_add(&mark->free_list, &free_list); + hlist_del_init_rcu(&mark->obj_list); + fsnotify_get_mark(mark); + } + spin_unlock(&mnt->mnt_root->d_lock); + + fsnotify_destroy_marks(&free_list); +} + +void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group) +{ + fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT); +} + +/* + * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types + * any notifier is interested in hearing for this mount point + */ +void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt) +{ + struct mount *m = real_mount(mnt); + + spin_lock(&mnt->mnt_root->d_lock); + m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks); + spin_unlock(&mnt->mnt_root->d_lock); +} + +void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark) +{ + struct vfsmount *mnt = mark->mnt; + struct mount *m = real_mount(mnt); + + BUG_ON(!mutex_is_locked(&mark->group->mark_mutex)); + assert_spin_locked(&mark->lock); + + spin_lock(&mnt->mnt_root->d_lock); + + hlist_del_init_rcu(&mark->obj_list); + mark->mnt = NULL; + + m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks); + spin_unlock(&mnt->mnt_root->d_lock); +} + +/* + * given a group and vfsmount, find the mark associated with that combination. + * if found take a reference to that mark and return it, else return NULL + */ +struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, + struct vfsmount *mnt) +{ + struct mount *m = real_mount(mnt); + struct fsnotify_mark *mark; + + spin_lock(&mnt->mnt_root->d_lock); + mark = fsnotify_find_mark(&m->mnt_fsnotify_marks, group); + spin_unlock(&mnt->mnt_root->d_lock); + + return mark; +} + +/* + * Attach an initialized mark to a given group and vfsmount. + * These marks may be used for the fsnotify backend to determine which + * event types should be delivered to which groups. + */ +int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark, + struct fsnotify_group *group, struct vfsmount *mnt, + int allow_dups) +{ + struct mount *m = real_mount(mnt); + int ret; + + mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT; + + BUG_ON(!mutex_is_locked(&group->mark_mutex)); + assert_spin_locked(&mark->lock); + + spin_lock(&mnt->mnt_root->d_lock); + mark->mnt = mnt; + ret = fsnotify_add_mark_list(&m->mnt_fsnotify_marks, mark, allow_dups); + m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks); + spin_unlock(&mnt->mnt_root->d_lock); + + return ret; +} |