diff options
Diffstat (limited to 'kernel/fs/notify/fanotify')
| -rw-r--r-- | kernel/fs/notify/fanotify/Kconfig | 26 | ||||
| -rw-r--r-- | kernel/fs/notify/fanotify/Makefile | 1 | ||||
| -rw-r--r-- | kernel/fs/notify/fanotify/fanotify.c | 270 | ||||
| -rw-r--r-- | kernel/fs/notify/fanotify/fanotify.h | 50 | ||||
| -rw-r--r-- | kernel/fs/notify/fanotify/fanotify_user.c | 940 |
5 files changed, 1287 insertions, 0 deletions
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); |