diff options
Diffstat (limited to 'kernel/ipc/mqueue.c')
| -rw-r--r-- | kernel/ipc/mqueue.c | 1474 |
1 files changed, 1474 insertions, 0 deletions
diff --git a/kernel/ipc/mqueue.c b/kernel/ipc/mqueue.c new file mode 100644 index 000000000..a24ba9fe5 --- /dev/null +++ b/kernel/ipc/mqueue.c @@ -0,0 +1,1474 @@ +/* + * POSIX message queues filesystem for Linux. + * + * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) + * Michal Wronski (michal.wronski@gmail.com) + * + * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) + * Lockless receive & send, fd based notify: + * Manfred Spraul (manfred@colorfullife.com) + * + * Audit: George Wilson (ltcgcw@us.ibm.com) + * + * This file is released under the GPL. + */ + +#include <linux/capability.h> +#include <linux/init.h> +#include <linux/pagemap.h> +#include <linux/file.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/sysctl.h> +#include <linux/poll.h> +#include <linux/mqueue.h> +#include <linux/msg.h> +#include <linux/skbuff.h> +#include <linux/vmalloc.h> +#include <linux/netlink.h> +#include <linux/syscalls.h> +#include <linux/audit.h> +#include <linux/signal.h> +#include <linux/mutex.h> +#include <linux/nsproxy.h> +#include <linux/pid.h> +#include <linux/ipc_namespace.h> +#include <linux/user_namespace.h> +#include <linux/slab.h> + +#include <net/sock.h> +#include "util.h" + +#define MQUEUE_MAGIC 0x19800202 +#define DIRENT_SIZE 20 +#define FILENT_SIZE 80 + +#define SEND 0 +#define RECV 1 + +#define STATE_NONE 0 +#define STATE_READY 1 + +struct posix_msg_tree_node { + struct rb_node rb_node; + struct list_head msg_list; + int priority; +}; + +struct ext_wait_queue { /* queue of sleeping tasks */ + struct task_struct *task; + struct list_head list; + struct msg_msg *msg; /* ptr of loaded message */ + int state; /* one of STATE_* values */ +}; + +struct mqueue_inode_info { + spinlock_t lock; + struct inode vfs_inode; + wait_queue_head_t wait_q; + + struct rb_root msg_tree; + struct posix_msg_tree_node *node_cache; + struct mq_attr attr; + + struct sigevent notify; + struct pid *notify_owner; + struct user_namespace *notify_user_ns; + struct user_struct *user; /* user who created, for accounting */ + struct sock *notify_sock; + struct sk_buff *notify_cookie; + + /* for tasks waiting for free space and messages, respectively */ + struct ext_wait_queue e_wait_q[2]; + + unsigned long qsize; /* size of queue in memory (sum of all msgs) */ +}; + +static const struct inode_operations mqueue_dir_inode_operations; +static const struct file_operations mqueue_file_operations; +static const struct super_operations mqueue_super_ops; +static void remove_notification(struct mqueue_inode_info *info); + +static struct kmem_cache *mqueue_inode_cachep; + +static struct ctl_table_header *mq_sysctl_table; + +static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) +{ + return container_of(inode, struct mqueue_inode_info, vfs_inode); +} + +/* + * This routine should be called with the mq_lock held. + */ +static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) +{ + return get_ipc_ns(inode->i_sb->s_fs_info); +} + +static struct ipc_namespace *get_ns_from_inode(struct inode *inode) +{ + struct ipc_namespace *ns; + + spin_lock(&mq_lock); + ns = __get_ns_from_inode(inode); + spin_unlock(&mq_lock); + return ns; +} + +/* Auxiliary functions to manipulate messages' list */ +static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info) +{ + struct rb_node **p, *parent = NULL; + struct posix_msg_tree_node *leaf; + + p = &info->msg_tree.rb_node; + while (*p) { + parent = *p; + leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node); + + if (likely(leaf->priority == msg->m_type)) + goto insert_msg; + else if (msg->m_type < leaf->priority) + p = &(*p)->rb_left; + else + p = &(*p)->rb_right; + } + if (info->node_cache) { + leaf = info->node_cache; + info->node_cache = NULL; + } else { + leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC); + if (!leaf) + return -ENOMEM; + INIT_LIST_HEAD(&leaf->msg_list); + info->qsize += sizeof(*leaf); + } + leaf->priority = msg->m_type; + rb_link_node(&leaf->rb_node, parent, p); + rb_insert_color(&leaf->rb_node, &info->msg_tree); +insert_msg: + info->attr.mq_curmsgs++; + info->qsize += msg->m_ts; + list_add_tail(&msg->m_list, &leaf->msg_list); + return 0; +} + +static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) +{ + struct rb_node **p, *parent = NULL; + struct posix_msg_tree_node *leaf; + struct msg_msg *msg; + +try_again: + p = &info->msg_tree.rb_node; + while (*p) { + parent = *p; + /* + * During insert, low priorities go to the left and high to the + * right. On receive, we want the highest priorities first, so + * walk all the way to the right. + */ + p = &(*p)->rb_right; + } + if (!parent) { + if (info->attr.mq_curmsgs) { + pr_warn_once("Inconsistency in POSIX message queue, " + "no tree element, but supposedly messages " + "should exist!\n"); + info->attr.mq_curmsgs = 0; + } + return NULL; + } + leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node); + if (unlikely(list_empty(&leaf->msg_list))) { + pr_warn_once("Inconsistency in POSIX message queue, " + "empty leaf node but we haven't implemented " + "lazy leaf delete!\n"); + rb_erase(&leaf->rb_node, &info->msg_tree); + if (info->node_cache) { + info->qsize -= sizeof(*leaf); + kfree(leaf); + } else { + info->node_cache = leaf; + } + goto try_again; + } else { + msg = list_first_entry(&leaf->msg_list, + struct msg_msg, m_list); + list_del(&msg->m_list); + if (list_empty(&leaf->msg_list)) { + rb_erase(&leaf->rb_node, &info->msg_tree); + if (info->node_cache) { + info->qsize -= sizeof(*leaf); + kfree(leaf); + } else { + info->node_cache = leaf; + } + } + } + info->attr.mq_curmsgs--; + info->qsize -= msg->m_ts; + return msg; +} + +static struct inode *mqueue_get_inode(struct super_block *sb, + struct ipc_namespace *ipc_ns, umode_t mode, + struct mq_attr *attr) +{ + struct user_struct *u = current_user(); + struct inode *inode; + int ret = -ENOMEM; + + inode = new_inode(sb); + if (!inode) + goto err; + + inode->i_ino = get_next_ino(); + inode->i_mode = mode; + inode->i_uid = current_fsuid(); + inode->i_gid = current_fsgid(); + inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME; + + if (S_ISREG(mode)) { + struct mqueue_inode_info *info; + unsigned long mq_bytes, mq_treesize; + + inode->i_fop = &mqueue_file_operations; + inode->i_size = FILENT_SIZE; + /* mqueue specific info */ + info = MQUEUE_I(inode); + spin_lock_init(&info->lock); + init_waitqueue_head(&info->wait_q); + INIT_LIST_HEAD(&info->e_wait_q[0].list); + INIT_LIST_HEAD(&info->e_wait_q[1].list); + info->notify_owner = NULL; + info->notify_user_ns = NULL; + info->qsize = 0; + info->user = NULL; /* set when all is ok */ + info->msg_tree = RB_ROOT; + info->node_cache = NULL; + memset(&info->attr, 0, sizeof(info->attr)); + info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, + ipc_ns->mq_msg_default); + info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max, + ipc_ns->mq_msgsize_default); + if (attr) { + info->attr.mq_maxmsg = attr->mq_maxmsg; + info->attr.mq_msgsize = attr->mq_msgsize; + } + /* + * We used to allocate a static array of pointers and account + * the size of that array as well as one msg_msg struct per + * possible message into the queue size. That's no longer + * accurate as the queue is now an rbtree and will grow and + * shrink depending on usage patterns. We can, however, still + * account one msg_msg struct per message, but the nodes are + * allocated depending on priority usage, and most programs + * only use one, or a handful, of priorities. However, since + * this is pinned memory, we need to assume worst case, so + * that means the min(mq_maxmsg, max_priorities) * struct + * posix_msg_tree_node. + */ + mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) + + min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) * + sizeof(struct posix_msg_tree_node); + + mq_bytes = mq_treesize + (info->attr.mq_maxmsg * + info->attr.mq_msgsize); + + spin_lock(&mq_lock); + if (u->mq_bytes + mq_bytes < u->mq_bytes || + u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) { + spin_unlock(&mq_lock); + /* mqueue_evict_inode() releases info->messages */ + ret = -EMFILE; + goto out_inode; + } + u->mq_bytes += mq_bytes; + spin_unlock(&mq_lock); + + /* all is ok */ + info->user = get_uid(u); + } else if (S_ISDIR(mode)) { + inc_nlink(inode); + /* Some things misbehave if size == 0 on a directory */ + inode->i_size = 2 * DIRENT_SIZE; + inode->i_op = &mqueue_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + } + + return inode; +out_inode: + iput(inode); +err: + return ERR_PTR(ret); +} + +static int mqueue_fill_super(struct super_block *sb, void *data, int silent) +{ + struct inode *inode; + struct ipc_namespace *ns = data; + + sb->s_blocksize = PAGE_CACHE_SIZE; + sb->s_blocksize_bits = PAGE_CACHE_SHIFT; + sb->s_magic = MQUEUE_MAGIC; + sb->s_op = &mqueue_super_ops; + + inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); + if (IS_ERR(inode)) + return PTR_ERR(inode); + + sb->s_root = d_make_root(inode); + if (!sb->s_root) + return -ENOMEM; + return 0; +} + +static struct dentry *mqueue_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, + void *data) +{ + if (!(flags & MS_KERNMOUNT)) { + struct ipc_namespace *ns = current->nsproxy->ipc_ns; + /* Don't allow mounting unless the caller has CAP_SYS_ADMIN + * over the ipc namespace. + */ + if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) + return ERR_PTR(-EPERM); + + data = ns; + } + return mount_ns(fs_type, flags, data, mqueue_fill_super); +} + +static void init_once(void *foo) +{ + struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; + + inode_init_once(&p->vfs_inode); +} + +static struct inode *mqueue_alloc_inode(struct super_block *sb) +{ + struct mqueue_inode_info *ei; + + ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); + if (!ei) + return NULL; + return &ei->vfs_inode; +} + +static void mqueue_i_callback(struct rcu_head *head) +{ + struct inode *inode = container_of(head, struct inode, i_rcu); + kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); +} + +static void mqueue_destroy_inode(struct inode *inode) +{ + call_rcu(&inode->i_rcu, mqueue_i_callback); +} + +static void mqueue_evict_inode(struct inode *inode) +{ + struct mqueue_inode_info *info; + struct user_struct *user; + unsigned long mq_bytes, mq_treesize; + struct ipc_namespace *ipc_ns; + struct msg_msg *msg; + + clear_inode(inode); + + if (S_ISDIR(inode->i_mode)) + return; + + ipc_ns = get_ns_from_inode(inode); + info = MQUEUE_I(inode); + spin_lock(&info->lock); + while ((msg = msg_get(info)) != NULL) + free_msg(msg); + kfree(info->node_cache); + spin_unlock(&info->lock); + + /* Total amount of bytes accounted for the mqueue */ + mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) + + min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) * + sizeof(struct posix_msg_tree_node); + + mq_bytes = mq_treesize + (info->attr.mq_maxmsg * + info->attr.mq_msgsize); + + user = info->user; + if (user) { + spin_lock(&mq_lock); + user->mq_bytes -= mq_bytes; + /* + * get_ns_from_inode() ensures that the + * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns + * to which we now hold a reference, or it is NULL. + * We can't put it here under mq_lock, though. + */ + if (ipc_ns) + ipc_ns->mq_queues_count--; + spin_unlock(&mq_lock); + free_uid(user); + } + if (ipc_ns) + put_ipc_ns(ipc_ns); +} + +static int mqueue_create(struct inode *dir, struct dentry *dentry, + umode_t mode, bool excl) +{ + struct inode *inode; + struct mq_attr *attr = dentry->d_fsdata; + int error; + struct ipc_namespace *ipc_ns; + + spin_lock(&mq_lock); + ipc_ns = __get_ns_from_inode(dir); + if (!ipc_ns) { + error = -EACCES; + goto out_unlock; + } + + if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && + !capable(CAP_SYS_RESOURCE)) { + error = -ENOSPC; + goto out_unlock; + } + ipc_ns->mq_queues_count++; + spin_unlock(&mq_lock); + + inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); + if (IS_ERR(inode)) { + error = PTR_ERR(inode); + spin_lock(&mq_lock); + ipc_ns->mq_queues_count--; + goto out_unlock; + } + + put_ipc_ns(ipc_ns); + dir->i_size += DIRENT_SIZE; + dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; + + d_instantiate(dentry, inode); + dget(dentry); + return 0; +out_unlock: + spin_unlock(&mq_lock); + if (ipc_ns) + put_ipc_ns(ipc_ns); + return error; +} + +static int mqueue_unlink(struct inode *dir, struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + + dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; + dir->i_size -= DIRENT_SIZE; + drop_nlink(inode); + dput(dentry); + return 0; +} + +/* +* This is routine for system read from queue file. +* To avoid mess with doing here some sort of mq_receive we allow +* to read only queue size & notification info (the only values +* that are interesting from user point of view and aren't accessible +* through std routines) +*/ +static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, + size_t count, loff_t *off) +{ + struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp)); + char buffer[FILENT_SIZE]; + ssize_t ret; + + spin_lock(&info->lock); + snprintf(buffer, sizeof(buffer), + "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", + info->qsize, + info->notify_owner ? info->notify.sigev_notify : 0, + (info->notify_owner && + info->notify.sigev_notify == SIGEV_SIGNAL) ? + info->notify.sigev_signo : 0, + pid_vnr(info->notify_owner)); + spin_unlock(&info->lock); + buffer[sizeof(buffer)-1] = '\0'; + + ret = simple_read_from_buffer(u_data, count, off, buffer, + strlen(buffer)); + if (ret <= 0) + return ret; + + file_inode(filp)->i_atime = file_inode(filp)->i_ctime = CURRENT_TIME; + return ret; +} + +static int mqueue_flush_file(struct file *filp, fl_owner_t id) +{ + struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp)); + + spin_lock(&info->lock); + if (task_tgid(current) == info->notify_owner) + remove_notification(info); + + spin_unlock(&info->lock); + return 0; +} + +static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) +{ + struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp)); + int retval = 0; + + poll_wait(filp, &info->wait_q, poll_tab); + + spin_lock(&info->lock); + if (info->attr.mq_curmsgs) + retval = POLLIN | POLLRDNORM; + + if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) + retval |= POLLOUT | POLLWRNORM; + spin_unlock(&info->lock); + + return retval; +} + +/* Adds current to info->e_wait_q[sr] before element with smaller prio */ +static void wq_add(struct mqueue_inode_info *info, int sr, + struct ext_wait_queue *ewp) +{ + struct ext_wait_queue *walk; + + ewp->task = current; + + list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { + if (walk->task->static_prio <= current->static_prio) { + list_add_tail(&ewp->list, &walk->list); + return; + } + } + list_add_tail(&ewp->list, &info->e_wait_q[sr].list); +} + +/* + * Puts current task to sleep. Caller must hold queue lock. After return + * lock isn't held. + * sr: SEND or RECV + */ +static int wq_sleep(struct mqueue_inode_info *info, int sr, + ktime_t *timeout, struct ext_wait_queue *ewp) +{ + int retval; + signed long time; + + wq_add(info, sr, ewp); + + for (;;) { + __set_current_state(TASK_INTERRUPTIBLE); + + spin_unlock(&info->lock); + time = schedule_hrtimeout_range_clock(timeout, 0, + HRTIMER_MODE_ABS, CLOCK_REALTIME); + + if (ewp->state == STATE_READY) { + retval = 0; + goto out; + } + spin_lock(&info->lock); + if (ewp->state == STATE_READY) { + retval = 0; + goto out_unlock; + } + if (signal_pending(current)) { + retval = -ERESTARTSYS; + break; + } + if (time == 0) { + retval = -ETIMEDOUT; + break; + } + } + list_del(&ewp->list); +out_unlock: + spin_unlock(&info->lock); +out: + return retval; +} + +/* + * Returns waiting task that should be serviced first or NULL if none exists + */ +static struct ext_wait_queue *wq_get_first_waiter( + struct mqueue_inode_info *info, int sr) +{ + struct list_head *ptr; + + ptr = info->e_wait_q[sr].list.prev; + if (ptr == &info->e_wait_q[sr].list) + return NULL; + return list_entry(ptr, struct ext_wait_queue, list); +} + + +static inline void set_cookie(struct sk_buff *skb, char code) +{ + ((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code; +} + +/* + * The next function is only to split too long sys_mq_timedsend + */ +static void __do_notify(struct mqueue_inode_info *info) +{ + /* notification + * invoked when there is registered process and there isn't process + * waiting synchronously for message AND state of queue changed from + * empty to not empty. Here we are sure that no one is waiting + * synchronously. */ + if (info->notify_owner && + info->attr.mq_curmsgs == 1) { + struct siginfo sig_i; + switch (info->notify.sigev_notify) { + case SIGEV_NONE: + break; + case SIGEV_SIGNAL: + /* sends signal */ + + sig_i.si_signo = info->notify.sigev_signo; + sig_i.si_errno = 0; + sig_i.si_code = SI_MESGQ; + sig_i.si_value = info->notify.sigev_value; + /* map current pid/uid into info->owner's namespaces */ + rcu_read_lock(); + sig_i.si_pid = task_tgid_nr_ns(current, + ns_of_pid(info->notify_owner)); + sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid()); + rcu_read_unlock(); + + kill_pid_info(info->notify.sigev_signo, + &sig_i, info->notify_owner); + break; + case SIGEV_THREAD: + set_cookie(info->notify_cookie, NOTIFY_WOKENUP); + netlink_sendskb(info->notify_sock, info->notify_cookie); + break; + } + /* after notification unregisters process */ + put_pid(info->notify_owner); + put_user_ns(info->notify_user_ns); + info->notify_owner = NULL; + info->notify_user_ns = NULL; + } + wake_up(&info->wait_q); +} + +static int prepare_timeout(const struct timespec __user *u_abs_timeout, + ktime_t *expires, struct timespec *ts) +{ + if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec))) + return -EFAULT; + if (!timespec_valid(ts)) + return -EINVAL; + + *expires = timespec_to_ktime(*ts); + return 0; +} + +static void remove_notification(struct mqueue_inode_info *info) +{ + if (info->notify_owner != NULL && + info->notify.sigev_notify == SIGEV_THREAD) { + set_cookie(info->notify_cookie, NOTIFY_REMOVED); + netlink_sendskb(info->notify_sock, info->notify_cookie); + } + put_pid(info->notify_owner); + put_user_ns(info->notify_user_ns); + info->notify_owner = NULL; + info->notify_user_ns = NULL; +} + +static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) +{ + int mq_treesize; + unsigned long total_size; + + if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) + return -EINVAL; + if (capable(CAP_SYS_RESOURCE)) { + if (attr->mq_maxmsg > HARD_MSGMAX || + attr->mq_msgsize > HARD_MSGSIZEMAX) + return -EINVAL; + } else { + if (attr->mq_maxmsg > ipc_ns->mq_msg_max || + attr->mq_msgsize > ipc_ns->mq_msgsize_max) + return -EINVAL; + } + /* check for overflow */ + if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) + return -EOVERFLOW; + mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) + + min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) * + sizeof(struct posix_msg_tree_node); + total_size = attr->mq_maxmsg * attr->mq_msgsize; + if (total_size + mq_treesize < total_size) + return -EOVERFLOW; + return 0; +} + +/* + * Invoked when creating a new queue via sys_mq_open + */ +static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir, + struct path *path, int oflag, umode_t mode, + struct mq_attr *attr) +{ + const struct cred *cred = current_cred(); + int ret; + + if (attr) { + ret = mq_attr_ok(ipc_ns, attr); + if (ret) + return ERR_PTR(ret); + /* store for use during create */ + path->dentry->d_fsdata = attr; + } else { + struct mq_attr def_attr; + + def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max, + ipc_ns->mq_msg_default); + def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max, + ipc_ns->mq_msgsize_default); + ret = mq_attr_ok(ipc_ns, &def_attr); + if (ret) + return ERR_PTR(ret); + } + + mode &= ~current_umask(); + ret = vfs_create(dir, path->dentry, mode, true); + path->dentry->d_fsdata = NULL; + if (ret) + return ERR_PTR(ret); + return dentry_open(path, oflag, cred); +} + +/* Opens existing queue */ +static struct file *do_open(struct path *path, int oflag) +{ + static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, + MAY_READ | MAY_WRITE }; + int acc; + if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) + return ERR_PTR(-EINVAL); + acc = oflag2acc[oflag & O_ACCMODE]; + if (inode_permission(d_inode(path->dentry), acc)) + return ERR_PTR(-EACCES); + return dentry_open(path, oflag, current_cred()); +} + +SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode, + struct mq_attr __user *, u_attr) +{ + struct path path; + struct file *filp; + struct filename *name; + struct mq_attr attr; + int fd, error; + struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; + struct vfsmount *mnt = ipc_ns->mq_mnt; + struct dentry *root = mnt->mnt_root; + int ro; + + if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) + return -EFAULT; + + audit_mq_open(oflag, mode, u_attr ? &attr : NULL); + + if (IS_ERR(name = getname(u_name))) + return PTR_ERR(name); + + fd = get_unused_fd_flags(O_CLOEXEC); + if (fd < 0) + goto out_putname; + + ro = mnt_want_write(mnt); /* we'll drop it in any case */ + error = 0; + mutex_lock(&d_inode(root)->i_mutex); + path.dentry = lookup_one_len(name->name, root, strlen(name->name)); + if (IS_ERR(path.dentry)) { + error = PTR_ERR(path.dentry); + goto out_putfd; + } + path.mnt = mntget(mnt); + + if (oflag & O_CREAT) { + if (d_really_is_positive(path.dentry)) { /* entry already exists */ + audit_inode(name, path.dentry, 0); + if (oflag & O_EXCL) { + error = -EEXIST; + goto out; + } + filp = do_open(&path, oflag); + } else { + if (ro) { + error = ro; + goto out; + } + audit_inode_parent_hidden(name, root); + filp = do_create(ipc_ns, d_inode(root), + &path, oflag, mode, + u_attr ? &attr : NULL); + } + } else { + if (d_really_is_negative(path.dentry)) { + error = -ENOENT; + goto out; + } + audit_inode(name, path.dentry, 0); + filp = do_open(&path, oflag); + } + + if (!IS_ERR(filp)) + fd_install(fd, filp); + else + error = PTR_ERR(filp); +out: + path_put(&path); +out_putfd: + if (error) { + put_unused_fd(fd); + fd = error; + } + mutex_unlock(&d_inode(root)->i_mutex); + if (!ro) + mnt_drop_write(mnt); +out_putname: + putname(name); + return fd; +} + +SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) +{ + int err; + struct filename *name; + struct dentry *dentry; + struct inode *inode = NULL; + struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; + struct vfsmount *mnt = ipc_ns->mq_mnt; + + name = getname(u_name); + if (IS_ERR(name)) + return PTR_ERR(name); + + audit_inode_parent_hidden(name, mnt->mnt_root); + err = mnt_want_write(mnt); + if (err) + goto out_name; + mutex_lock_nested(&d_inode(mnt->mnt_root)->i_mutex, I_MUTEX_PARENT); + dentry = lookup_one_len(name->name, mnt->mnt_root, + strlen(name->name)); + if (IS_ERR(dentry)) { + err = PTR_ERR(dentry); + goto out_unlock; + } + + inode = d_inode(dentry); + if (!inode) { + err = -ENOENT; + } else { + ihold(inode); + err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL); + } + dput(dentry); + +out_unlock: + mutex_unlock(&d_inode(mnt->mnt_root)->i_mutex); + if (inode) + iput(inode); + mnt_drop_write(mnt); +out_name: + putname(name); + + return err; +} + +/* Pipelined send and receive functions. + * + * If a receiver finds no waiting message, then it registers itself in the + * list of waiting receivers. A sender checks that list before adding the new + * message into the message array. If there is a waiting receiver, then it + * bypasses the message array and directly hands the message over to the + * receiver. The receiver accepts the message and returns without grabbing the + * queue spinlock: + * + * - Set pointer to message. + * - Queue the receiver task for later wakeup (without the info->lock). + * - Update its state to STATE_READY. Now the receiver can continue. + * - Wake up the process after the lock is dropped. Should the process wake up + * before this wakeup (due to a timeout or a signal) it will either see + * STATE_READY and continue or acquire the lock to check the state again. + * + * The same algorithm is used for senders. + */ + +/* pipelined_send() - send a message directly to the task waiting in + * sys_mq_timedreceive() (without inserting message into a queue). + */ +static inline void pipelined_send(struct wake_q_head *wake_q, + struct mqueue_inode_info *info, + struct msg_msg *message, + struct ext_wait_queue *receiver) +{ + receiver->msg = message; + list_del(&receiver->list); + wake_q_add(wake_q, receiver->task); + /* + * Rely on the implicit cmpxchg barrier from wake_q_add such + * that we can ensure that updating receiver->state is the last + * write operation: As once set, the receiver can continue, + * and if we don't have the reference count from the wake_q, + * yet, at that point we can later have a use-after-free + * condition and bogus wakeup. + */ + receiver->state = STATE_READY; +} + +/* pipelined_receive() - if there is task waiting in sys_mq_timedsend() + * gets its message and put to the queue (we have one free place for sure). */ +static inline void pipelined_receive(struct wake_q_head *wake_q, + struct mqueue_inode_info *info) +{ + struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); + + if (!sender) { + /* for poll */ + wake_up_interruptible(&info->wait_q); + return; + } + if (msg_insert(sender->msg, info)) + return; + + list_del(&sender->list); + wake_q_add(wake_q, sender->task); + sender->state = STATE_READY; +} + +SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, + size_t, msg_len, unsigned int, msg_prio, + const struct timespec __user *, u_abs_timeout) +{ + struct fd f; + struct inode *inode; + struct ext_wait_queue wait; + struct ext_wait_queue *receiver; + struct msg_msg *msg_ptr; + struct mqueue_inode_info *info; + ktime_t expires, *timeout = NULL; + struct timespec ts; + struct posix_msg_tree_node *new_leaf = NULL; + int ret = 0; + WAKE_Q(wake_q); + + if (u_abs_timeout) { + int res = prepare_timeout(u_abs_timeout, &expires, &ts); + if (res) + return res; + timeout = &expires; + } + + if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) + return -EINVAL; + + audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL); + + f = fdget(mqdes); + if (unlikely(!f.file)) { + ret = -EBADF; + goto out; + } + + inode = file_inode(f.file); + if (unlikely(f.file->f_op != &mqueue_file_operations)) { + ret = -EBADF; + goto out_fput; + } + info = MQUEUE_I(inode); + audit_file(f.file); + + if (unlikely(!(f.file->f_mode & FMODE_WRITE))) { + ret = -EBADF; + goto out_fput; + } + + if (unlikely(msg_len > info->attr.mq_msgsize)) { + ret = -EMSGSIZE; + goto out_fput; + } + + /* First try to allocate memory, before doing anything with + * existing queues. */ + msg_ptr = load_msg(u_msg_ptr, msg_len); + if (IS_ERR(msg_ptr)) { + ret = PTR_ERR(msg_ptr); + goto out_fput; + } + msg_ptr->m_ts = msg_len; + msg_ptr->m_type = msg_prio; + + /* + * msg_insert really wants us to have a valid, spare node struct so + * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will + * fall back to that if necessary. + */ + if (!info->node_cache) + new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL); + + spin_lock(&info->lock); + + if (!info->node_cache && new_leaf) { + /* Save our speculative allocation into the cache */ + INIT_LIST_HEAD(&new_leaf->msg_list); + info->node_cache = new_leaf; + info->qsize += sizeof(*new_leaf); + new_leaf = NULL; + } else { + kfree(new_leaf); + } + + if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { + if (f.file->f_flags & O_NONBLOCK) { + ret = -EAGAIN; + } else { + wait.task = current; + wait.msg = (void *) msg_ptr; + wait.state = STATE_NONE; + ret = wq_sleep(info, SEND, timeout, &wait); + /* + * wq_sleep must be called with info->lock held, and + * returns with the lock released + */ + goto out_free; + } + } else { + receiver = wq_get_first_waiter(info, RECV); + if (receiver) { + pipelined_send(&wake_q, info, msg_ptr, receiver); + } else { + /* adds message to the queue */ + ret = msg_insert(msg_ptr, info); + if (ret) + goto out_unlock; + __do_notify(info); + } + inode->i_atime = inode->i_mtime = inode->i_ctime = + CURRENT_TIME; + } +out_unlock: + spin_unlock(&info->lock); + wake_up_q(&wake_q); +out_free: + if (ret) + free_msg(msg_ptr); +out_fput: + fdput(f); +out: + return ret; +} + +SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, + size_t, msg_len, unsigned int __user *, u_msg_prio, + const struct timespec __user *, u_abs_timeout) +{ + ssize_t ret; + struct msg_msg *msg_ptr; + struct fd f; + struct inode *inode; + struct mqueue_inode_info *info; + struct ext_wait_queue wait; + ktime_t expires, *timeout = NULL; + struct timespec ts; + struct posix_msg_tree_node *new_leaf = NULL; + + if (u_abs_timeout) { + int res = prepare_timeout(u_abs_timeout, &expires, &ts); + if (res) + return res; + timeout = &expires; + } + + audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL); + + f = fdget(mqdes); + if (unlikely(!f.file)) { + ret = -EBADF; + goto out; + } + + inode = file_inode(f.file); + if (unlikely(f.file->f_op != &mqueue_file_operations)) { + ret = -EBADF; + goto out_fput; + } + info = MQUEUE_I(inode); + audit_file(f.file); + + if (unlikely(!(f.file->f_mode & FMODE_READ))) { + ret = -EBADF; + goto out_fput; + } + + /* checks if buffer is big enough */ + if (unlikely(msg_len < info->attr.mq_msgsize)) { + ret = -EMSGSIZE; + goto out_fput; + } + + /* + * msg_insert really wants us to have a valid, spare node struct so + * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will + * fall back to that if necessary. + */ + if (!info->node_cache) + new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL); + + spin_lock(&info->lock); + + if (!info->node_cache && new_leaf) { + /* Save our speculative allocation into the cache */ + INIT_LIST_HEAD(&new_leaf->msg_list); + info->node_cache = new_leaf; + info->qsize += sizeof(*new_leaf); + } else { + kfree(new_leaf); + } + + if (info->attr.mq_curmsgs == 0) { + if (f.file->f_flags & O_NONBLOCK) { + spin_unlock(&info->lock); + ret = -EAGAIN; + } else { + wait.task = current; + wait.state = STATE_NONE; + ret = wq_sleep(info, RECV, timeout, &wait); + msg_ptr = wait.msg; + } + } else { + WAKE_Q(wake_q); + + msg_ptr = msg_get(info); + + inode->i_atime = inode->i_mtime = inode->i_ctime = + CURRENT_TIME; + + /* There is now free space in queue. */ + pipelined_receive(&wake_q, info); + spin_unlock(&info->lock); + wake_up_q(&wake_q); + ret = 0; + } + if (ret == 0) { + ret = msg_ptr->m_ts; + + if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || + store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { + ret = -EFAULT; + } + free_msg(msg_ptr); + } +out_fput: + fdput(f); +out: + return ret; +} + +/* + * Notes: the case when user wants us to deregister (with NULL as pointer) + * and he isn't currently owner of notification, will be silently discarded. + * It isn't explicitly defined in the POSIX. + */ +SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, + const struct sigevent __user *, u_notification) +{ + int ret; + struct fd f; + struct sock *sock; + struct inode *inode; + struct sigevent notification; + struct mqueue_inode_info *info; + struct sk_buff *nc; + + if (u_notification) { + if (copy_from_user(¬ification, u_notification, + sizeof(struct sigevent))) + return -EFAULT; + } + + audit_mq_notify(mqdes, u_notification ? ¬ification : NULL); + + nc = NULL; + sock = NULL; + if (u_notification != NULL) { + if (unlikely(notification.sigev_notify != SIGEV_NONE && + notification.sigev_notify != SIGEV_SIGNAL && + notification.sigev_notify != SIGEV_THREAD)) + return -EINVAL; + if (notification.sigev_notify == SIGEV_SIGNAL && + !valid_signal(notification.sigev_signo)) { + return -EINVAL; + } + if (notification.sigev_notify == SIGEV_THREAD) { + long timeo; + + /* create the notify skb */ + nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); + if (!nc) { + ret = -ENOMEM; + goto out; + } + if (copy_from_user(nc->data, + notification.sigev_value.sival_ptr, + NOTIFY_COOKIE_LEN)) { + ret = -EFAULT; + goto out; + } + + /* TODO: add a header? */ + skb_put(nc, NOTIFY_COOKIE_LEN); + /* and attach it to the socket */ +retry: + f = fdget(notification.sigev_signo); + if (!f.file) { + ret = -EBADF; + goto out; + } + sock = netlink_getsockbyfilp(f.file); + fdput(f); + if (IS_ERR(sock)) { + ret = PTR_ERR(sock); + sock = NULL; + goto out; + } + + timeo = MAX_SCHEDULE_TIMEOUT; + ret = netlink_attachskb(sock, nc, &timeo, NULL); + if (ret == 1) + goto retry; + if (ret) { + sock = NULL; + nc = NULL; + goto out; + } + } + } + + f = fdget(mqdes); + if (!f.file) { + ret = -EBADF; + goto out; + } + + inode = file_inode(f.file); + if (unlikely(f.file->f_op != &mqueue_file_operations)) { + ret = -EBADF; + goto out_fput; + } + info = MQUEUE_I(inode); + + ret = 0; + spin_lock(&info->lock); + if (u_notification == NULL) { + if (info->notify_owner == task_tgid(current)) { + remove_notification(info); + inode->i_atime = inode->i_ctime = CURRENT_TIME; + } + } else if (info->notify_owner != NULL) { + ret = -EBUSY; + } else { + switch (notification.sigev_notify) { + case SIGEV_NONE: + info->notify.sigev_notify = SIGEV_NONE; + break; + case SIGEV_THREAD: + info->notify_sock = sock; + info->notify_cookie = nc; + sock = NULL; + nc = NULL; + info->notify.sigev_notify = SIGEV_THREAD; + break; + case SIGEV_SIGNAL: + info->notify.sigev_signo = notification.sigev_signo; + info->notify.sigev_value = notification.sigev_value; + info->notify.sigev_notify = SIGEV_SIGNAL; + break; + } + + info->notify_owner = get_pid(task_tgid(current)); + info->notify_user_ns = get_user_ns(current_user_ns()); + inode->i_atime = inode->i_ctime = CURRENT_TIME; + } + spin_unlock(&info->lock); +out_fput: + fdput(f); +out: + if (sock) + netlink_detachskb(sock, nc); + else if (nc) + dev_kfree_skb(nc); + + return ret; +} + +SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, + const struct mq_attr __user *, u_mqstat, + struct mq_attr __user *, u_omqstat) +{ + int ret; + struct mq_attr mqstat, omqstat; + struct fd f; + struct inode *inode; + struct mqueue_inode_info *info; + + if (u_mqstat != NULL) { + if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr))) + return -EFAULT; + if (mqstat.mq_flags & (~O_NONBLOCK)) + return -EINVAL; + } + + f = fdget(mqdes); + if (!f.file) { + ret = -EBADF; + goto out; + } + + inode = file_inode(f.file); + if (unlikely(f.file->f_op != &mqueue_file_operations)) { + ret = -EBADF; + goto out_fput; + } + info = MQUEUE_I(inode); + + spin_lock(&info->lock); + + omqstat = info->attr; + omqstat.mq_flags = f.file->f_flags & O_NONBLOCK; + if (u_mqstat) { + audit_mq_getsetattr(mqdes, &mqstat); + spin_lock(&f.file->f_lock); + if (mqstat.mq_flags & O_NONBLOCK) + f.file->f_flags |= O_NONBLOCK; + else + f.file->f_flags &= ~O_NONBLOCK; + spin_unlock(&f.file->f_lock); + + inode->i_atime = inode->i_ctime = CURRENT_TIME; + } + + spin_unlock(&info->lock); + + ret = 0; + if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat, + sizeof(struct mq_attr))) + ret = -EFAULT; + +out_fput: + fdput(f); +out: + return ret; +} + +static const struct inode_operations mqueue_dir_inode_operations = { + .lookup = simple_lookup, + .create = mqueue_create, + .unlink = mqueue_unlink, +}; + +static const struct file_operations mqueue_file_operations = { + .flush = mqueue_flush_file, + .poll = mqueue_poll_file, + .read = mqueue_read_file, + .llseek = default_llseek, +}; + +static const struct super_operations mqueue_super_ops = { + .alloc_inode = mqueue_alloc_inode, + .destroy_inode = mqueue_destroy_inode, + .evict_inode = mqueue_evict_inode, + .statfs = simple_statfs, +}; + +static struct file_system_type mqueue_fs_type = { + .name = "mqueue", + .mount = mqueue_mount, + .kill_sb = kill_litter_super, + .fs_flags = FS_USERNS_MOUNT, +}; + +int mq_init_ns(struct ipc_namespace *ns) +{ + ns->mq_queues_count = 0; + ns->mq_queues_max = DFLT_QUEUESMAX; + ns->mq_msg_max = DFLT_MSGMAX; + ns->mq_msgsize_max = DFLT_MSGSIZEMAX; + ns->mq_msg_default = DFLT_MSG; + ns->mq_msgsize_default = DFLT_MSGSIZE; + + ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); + if (IS_ERR(ns->mq_mnt)) { + int err = PTR_ERR(ns->mq_mnt); + ns->mq_mnt = NULL; + return err; + } + return 0; +} + +void mq_clear_sbinfo(struct ipc_namespace *ns) +{ + ns->mq_mnt->mnt_sb->s_fs_info = NULL; +} + +void mq_put_mnt(struct ipc_namespace *ns) +{ + kern_unmount(ns->mq_mnt); +} + +static int __init init_mqueue_fs(void) +{ + int error; + + mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", + sizeof(struct mqueue_inode_info), 0, + SLAB_HWCACHE_ALIGN, init_once); + if (mqueue_inode_cachep == NULL) + return -ENOMEM; + + /* ignore failures - they are not fatal */ + mq_sysctl_table = mq_register_sysctl_table(); + + error = register_filesystem(&mqueue_fs_type); + if (error) + goto out_sysctl; + + spin_lock_init(&mq_lock); + + error = mq_init_ns(&init_ipc_ns); + if (error) + goto out_filesystem; + + return 0; + +out_filesystem: + unregister_filesystem(&mqueue_fs_type); +out_sysctl: + if (mq_sysctl_table) + unregister_sysctl_table(mq_sysctl_table); + kmem_cache_destroy(mqueue_inode_cachep); + return error; +} + +device_initcall(init_mqueue_fs); |