/* * POSIX message queues filesystem for Linux. * * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) * Michal Wronski (Michal.Wronski@motorola.com) * * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) * Lockless receive & send, fd based notify: * Manfred Spraul (manfred@colorfullife.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/netlink.h> #include <linux/syscalls.h> #include <linux/signal.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_PENDING 1 #define STATE_READY 2 /* used by sysctl */ #define FS_MQUEUE 1 #define CTL_QUEUESMAX 2 #define CTL_MSGMAX 3 #define CTL_MSGSIZEMAX 4 /* default values */ #define DFLT_QUEUESMAX 256 /* max number of message queues */ #define DFLT_MSGMAX 10 /* max number of messages in each queue */ #define HARD_MSGMAX (131072/sizeof(void*)) #define DFLT_MSGSIZEMAX 8192 /* max message size */ #define NOTIFY_COOKIE_LEN 32 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 msg_msg **messages; struct mq_attr attr; struct sigevent notify; pid_t notify_owner; 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 struct inode_operations mqueue_dir_inode_operations; static struct file_operations mqueue_file_operations; static struct super_operations mqueue_super_ops; static void remove_notification(struct mqueue_inode_info *info); static spinlock_t mq_lock; static kmem_cache_t *mqueue_inode_cachep; static struct vfsmount *mqueue_mnt; static unsigned int queues_count; static unsigned int queues_max = DFLT_QUEUESMAX; static unsigned int msg_max = DFLT_MSGMAX; static unsigned int msgsize_max = DFLT_MSGSIZEMAX; 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); } static struct inode *mqueue_get_inode(struct super_block *sb, int mode, struct mq_attr *attr) { struct inode *inode; inode = new_inode(sb); if (inode) { inode->i_mode = mode; inode->i_uid = current->fsuid; inode->i_gid = current->fsgid; inode->i_blksize = PAGE_CACHE_SIZE; inode->i_blocks = 0; inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME; if (S_ISREG(mode)) { struct mqueue_inode_info *info; struct task_struct *p = current; struct user_struct *u = p->user; unsigned long mq_bytes, mq_msg_tblsz; 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->messages = NULL; info->notify_owner = 0; info->qsize = 0; info->user = NULL; /* set when all is ok */ memset(&info->attr, 0, sizeof(info->attr)); info->attr.mq_maxmsg = DFLT_MSGMAX; info->attr.mq_msgsize = DFLT_MSGSIZEMAX; if (attr) { info->attr.mq_maxmsg = attr->mq_maxmsg; info->attr.mq_msgsize = attr->mq_msgsize; } mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *); mq_bytes = (mq_msg_tblsz + (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 > p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) { spin_unlock(&mq_lock); goto out_inode; } u->mq_bytes += mq_bytes; spin_unlock(&mq_lock); info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL); if (!info->messages) { spin_lock(&mq_lock); u->mq_bytes -= mq_bytes; spin_unlock(&mq_lock); goto out_inode; } /* all is ok */ info->user = get_uid(u); } else if (S_ISDIR(mode)) { inode->i_nlink++; /* 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: make_bad_inode(inode); iput(inode); return NULL; } static int mqueue_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; 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, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); if (!inode) return -ENOMEM; sb->s_root = d_alloc_root(inode); if (!sb->s_root) { iput(inode); return -ENOMEM; } return 0; } static struct super_block *mqueue_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return get_sb_single(fs_type, flags, data, mqueue_fill_super); } static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags) { struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) 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, SLAB_KERNEL); if (!ei) return NULL; return &ei->vfs_inode; } static void mqueue_destroy_inode(struct inode *inode) { kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); } static void mqueue_delete_inode(struct inode *inode) { struct mqueue_inode_info *info; struct user_struct *user; unsigned long mq_bytes; int i; if (S_ISDIR(inode->i_mode)) { clear_inode(inode); return; } info = MQUEUE_I(inode); spin_lock(&info->lock); for (i = 0; i < info->attr.mq_curmsgs; i++) free_msg(info->messages[i]); kfree(info->messages); spin_unlock(&info->lock); clear_inode(inode); mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) + (info->attr.mq_maxmsg * info->attr.mq_msgsize)); user = info->user; if (user) { spin_lock(&mq_lock); user->mq_bytes -= mq_bytes; queues_count--; spin_unlock(&mq_lock); free_uid(user); } } static int mqueue_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd) { struct inode *inode; struct mq_attr *attr = dentry->d_fsdata; int error; spin_lock(&mq_lock); if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) { error = -ENOSPC; goto out_lock; } queues_count++; spin_unlock(&mq_lock); inode = mqueue_get_inode(dir->i_sb, mode, attr); if (!inode) { error = -ENOMEM; spin_lock(&mq_lock); queues_count--; goto out_lock; } 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_lock: spin_unlock(&mq_lock); return error; } static int mqueue_unlink(struct inode *dir, struct dentry *dentry) { struct inode *inode = dentry->d_inode; dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME; dir->i_size -= DIRENT_SIZE; inode->i_nlink--; 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(filp->f_dentry->d_inode); char buffer[FILENT_SIZE]; size_t slen; loff_t o; if (!count) return 0; 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, info->notify_owner); spin_unlock(&info->lock); buffer[sizeof(buffer)-1] = '\0'; slen = strlen(buffer)+1; o = *off; if (o > slen) return 0; if (o + count > slen) count = slen - o; if (copy_to_user(u_data, buffer + o, count)) return -EFAULT; *off = o + count; filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME; return count; } static int mqueue_flush_file(struct file *filp) { struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode); spin_lock(&info->lock); if (current->tgid == 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(filp->f_dentry->d_inode); 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, long 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_timeout(timeout); while (ewp->state == STATE_PENDING) cpu_relax(); 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); } /* Auxiliary functions to manipulate messages' list */ static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info) { int k; k = info->attr.mq_curmsgs - 1; while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) { info->messages[k + 1] = info->messages[k]; k--; } info->attr.mq_curmsgs++; info->qsize += ptr->m_ts; info->messages[k + 1] = ptr; } static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) { info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts; return info->messages[info->attr.mq_curmsgs]; } 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; sig_i.si_pid = current->tgid; sig_i.si_uid = current->uid; kill_proc_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, 0); break; } /* after notification unregisters process */ info->notify_owner = 0; } wake_up(&info->wait_q); } static long prepare_timeout(const struct timespec __user *u_arg) { struct timespec ts, nowts; long timeout; if (u_arg) { if (unlikely(copy_from_user(&ts, u_arg, sizeof(struct timespec)))) return -EFAULT; if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0 || ts.tv_nsec >= NSEC_PER_SEC)) return -EINVAL; nowts = CURRENT_TIME; /* first subtract as jiffies can't be too big */ ts.tv_sec -= nowts.tv_sec; if (ts.tv_nsec < nowts.tv_nsec) { ts.tv_nsec += NSEC_PER_SEC; ts.tv_sec--; } ts.tv_nsec -= nowts.tv_nsec; if (ts.tv_sec < 0) return 0; timeout = timespec_to_jiffies(&ts) + 1; } else return MAX_SCHEDULE_TIMEOUT; return timeout; } static void remove_notification(struct mqueue_inode_info *info) { if (info->notify_owner != 0 && info->notify.sigev_notify == SIGEV_THREAD) { set_cookie(info->notify_cookie, NOTIFY_REMOVED); netlink_sendskb(info->notify_sock, info->notify_cookie, 0); } info->notify_owner = 0; } static int mq_attr_ok(struct mq_attr *attr) { if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) return 0; if (capable(CAP_SYS_RESOURCE)) { if (attr->mq_maxmsg > HARD_MSGMAX) return 0; } else { if (attr->mq_maxmsg > msg_max || attr->mq_msgsize > msgsize_max) return 0; } /* check for overflow */ if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) return 0; if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) + (attr->mq_maxmsg * sizeof (struct msg_msg *)) < (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize)) return 0; return 1; } /* * Invoked when creating a new queue via sys_mq_open */ static struct file *do_create(struct dentry *dir, struct dentry *dentry, int oflag, mode_t mode, struct mq_attr __user *u_attr) { struct mq_attr attr; int ret; if (u_attr) { ret = -EFAULT; if (copy_from_user(&attr, u_attr, sizeof(attr))) goto out; ret = -EINVAL; if (!mq_attr_ok(&attr)) goto out; /* store for use during create */ dentry->d_fsdata = &attr; } mode &= ~current->fs->umask; ret = vfs_create(dir->d_inode, dentry, mode, NULL); dentry->d_fsdata = NULL; if (ret) goto out; return dentry_open(dentry, mqueue_mnt, oflag); out: dput(dentry); mntput(mqueue_mnt); return ERR_PTR(ret); } /* Opens existing queue */ static struct file *do_open(struct dentry *dentry, int oflag) { static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, MAY_READ | MAY_WRITE }; if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) { dput(dentry); mntput(mqueue_mnt); return ERR_PTR(-EINVAL); } if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) { dput(dentry); mntput(mqueue_mnt); return ERR_PTR(-EACCES); } return dentry_open(dentry, mqueue_mnt, oflag); } asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode, struct mq_attr __user *u_attr) { struct dentry *dentry; struct file *filp; char *name; int fd, error; if (IS_ERR(name = getname(u_name))) return PTR_ERR(name); fd = get_unused_fd(); if (fd < 0) goto out_putname; mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); if (IS_ERR(dentry)) { error = PTR_ERR(dentry); goto out_err; } mntget(mqueue_mnt); if (oflag & O_CREAT) { if (dentry->d_inode) { /* entry already exists */ error = -EEXIST; if (oflag & O_EXCL) goto out; filp = do_open(dentry, oflag); } else { filp = do_create(mqueue_mnt->mnt_root, dentry, oflag, mode, u_attr); } } else { error = -ENOENT; if (!dentry->d_inode) goto out; filp = do_open(dentry, oflag); } if (IS_ERR(filp)) { error = PTR_ERR(filp); goto out_putfd; } set_close_on_exec(fd, 1); fd_install(fd, filp); goto out_upsem; out: dput(dentry); mntput(mqueue_mnt); out_putfd: put_unused_fd(fd); out_err: fd = error; out_upsem: mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); out_putname: putname(name); return fd; } asmlinkage long sys_mq_unlink(const char __user *u_name) { int err; char *name; struct dentry *dentry; struct inode *inode = NULL; name = getname(u_name); if (IS_ERR(name)) return PTR_ERR(name); mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex); dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name)); if (IS_ERR(dentry)) { err = PTR_ERR(dentry); goto out_unlock; } if (!dentry->d_inode) { err = -ENOENT; goto out_err; } inode = dentry->d_inode; if (inode) atomic_inc(&inode->i_count); err = vfs_unlink(dentry->d_parent->d_inode, dentry); out_err: dput(dentry); out_unlock: mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex); putname(name); if (inode) iput(inode); 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. Therefore an intermediate STATE_PENDING state and memory barriers * are necessary. The same algorithm is used for sysv semaphores, see * ipc/sem.c fore more details. * * 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 mqueue_inode_info *info, struct msg_msg *message, struct ext_wait_queue *receiver) { receiver->msg = message; list_del(&receiver->list); receiver->state = STATE_PENDING; wake_up_process(receiver->task); smp_wmb(); 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 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; } msg_insert(sender->msg, info); list_del(&sender->list); sender->state = STATE_PENDING; wake_up_process(sender->task); smp_wmb(); sender->state = STATE_READY; } asmlinkage long sys_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 file *filp; struct inode *inode; struct ext_wait_queue wait; struct ext_wait_queue *receiver; struct msg_msg *msg_ptr; struct mqueue_inode_info *info; long timeout; int ret; if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) return -EINVAL; timeout = prepare_timeout(u_abs_timeout); ret = -EBADF; filp = fget(mqdes); if (unlikely(!filp)) goto out; inode = filp->f_dentry->d_inode; if (unlikely(filp->f_op != &mqueue_file_operations)) goto out_fput; info = MQUEUE_I(inode); if (unlikely(!(filp->f_mode & FMODE_WRITE))) 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; spin_lock(&info->lock); if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { if (filp->f_flags & O_NONBLOCK) { spin_unlock(&info->lock); ret = -EAGAIN; } else if (unlikely(timeout < 0)) { spin_unlock(&info->lock); ret = timeout; } else { wait.task = current; wait.msg = (void *) msg_ptr; wait.state = STATE_NONE; ret = wq_sleep(info, SEND, timeout, &wait); } if (ret < 0) free_msg(msg_ptr); } else { receiver = wq_get_first_waiter(info, RECV); if (receiver) { pipelined_send(info, msg_ptr, receiver); } else { /* adds message to the queue */ msg_insert(msg_ptr, info); __do_notify(info); } inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; spin_unlock(&info->lock); ret = 0; } out_fput: fput(filp); out: return ret; } asmlinkage ssize_t sys_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) { long timeout; ssize_t ret; struct msg_msg *msg_ptr; struct file *filp; struct inode *inode; struct mqueue_inode_info *info; struct ext_wait_queue wait; timeout = prepare_timeout(u_abs_timeout); ret = -EBADF; filp = fget(mqdes); if (unlikely(!filp)) goto out; inode = filp->f_dentry->d_inode; if (unlikely(filp->f_op != &mqueue_file_operations)) goto out_fput; info = MQUEUE_I(inode); if (unlikely(!(filp->f_mode & FMODE_READ))) goto out_fput; /* checks if buffer is big enough */ if (unlikely(msg_len < info->attr.mq_msgsize)) { ret = -EMSGSIZE; goto out_fput; } spin_lock(&info->lock); if (info->attr.mq_curmsgs == 0) { if (filp->f_flags & O_NONBLOCK) { spin_unlock(&info->lock); ret = -EAGAIN; msg_ptr = NULL; } else if (unlikely(timeout < 0)) { spin_unlock(&info->lock); ret = timeout; msg_ptr = NULL; } else { wait.task = current; wait.state = STATE_NONE; ret = wq_sleep(info, RECV, timeout, &wait); msg_ptr = wait.msg; } } else { 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(info); spin_unlock(&info->lock); 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: fput(filp); 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. */ asmlinkage long sys_mq_notify(mqd_t mqdes, const struct sigevent __user *u_notification) { int ret; struct file *filp; struct sock *sock; struct inode *inode; struct sigevent notification; struct mqueue_inode_info *info; struct sk_buff *nc; nc = NULL; sock = NULL; if (u_notification != NULL) { if (copy_from_user(¬ification, u_notification, sizeof(struct sigevent))) return -EFAULT; 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) { /* create the notify skb */ nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); ret = -ENOMEM; if (!nc) goto out; ret = -EFAULT; if (copy_from_user(nc->data, notification.sigev_value.sival_ptr, NOTIFY_COOKIE_LEN)) { goto out; } /* TODO: add a header? */ skb_put(nc, NOTIFY_COOKIE_LEN); /* and attach it to the socket */ retry: filp = fget(notification.sigev_signo); ret = -EBADF; if (!filp) goto out; sock = netlink_getsockbyfilp(filp); fput(filp); if (IS_ERR(sock)) { ret = PTR_ERR(sock); sock = NULL; goto out; } ret = netlink_attachskb(sock, nc, 0, MAX_SCHEDULE_TIMEOUT, NULL); if (ret == 1) goto retry; if (ret) { sock = NULL; nc = NULL; goto out; } } } ret = -EBADF; filp = fget(mqdes); if (!filp) goto out; inode = filp->f_dentry->d_inode; if (unlikely(filp->f_op != &mqueue_file_operations)) goto out_fput; info = MQUEUE_I(inode); ret = 0; spin_lock(&info->lock); if (u_notification == NULL) { if (info->notify_owner == current->tgid) { remove_notification(info); inode->i_atime = inode->i_ctime = CURRENT_TIME; } } else if (info->notify_owner != 0) { 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 = current->tgid; inode->i_atime = inode->i_ctime = CURRENT_TIME; } spin_unlock(&info->lock); out_fput: fput(filp); out: if (sock) { netlink_detachskb(sock, nc); } else if (nc) { dev_kfree_skb(nc); } return ret; } asmlinkage long sys_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 file *filp; 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; } ret = -EBADF; filp = fget(mqdes); if (!filp) goto out; inode = filp->f_dentry->d_inode; if (unlikely(filp->f_op != &mqueue_file_operations)) goto out_fput; info = MQUEUE_I(inode); spin_lock(&info->lock); omqstat = info->attr; omqstat.mq_flags = filp->f_flags & O_NONBLOCK; if (u_mqstat) { if (mqstat.mq_flags & O_NONBLOCK) filp->f_flags |= O_NONBLOCK; else filp->f_flags &= ~O_NONBLOCK; 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: fput(filp); out: return ret; } static struct inode_operations mqueue_dir_inode_operations = { .lookup = simple_lookup, .create = mqueue_create, .unlink = mqueue_unlink, }; static struct file_operations mqueue_file_operations = { .flush = mqueue_flush_file, .poll = mqueue_poll_file, .read = mqueue_read_file, }; static struct super_operations mqueue_super_ops = { .alloc_inode = mqueue_alloc_inode, .destroy_inode = mqueue_destroy_inode, .statfs = simple_statfs, .delete_inode = mqueue_delete_inode, .drop_inode = generic_delete_inode, }; static struct file_system_type mqueue_fs_type = { .name = "mqueue", .get_sb = mqueue_get_sb, .kill_sb = kill_litter_super, }; static int msg_max_limit_min = DFLT_MSGMAX; static int msg_max_limit_max = HARD_MSGMAX; static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX; static int msg_maxsize_limit_max = INT_MAX; static ctl_table mq_sysctls[] = { { .ctl_name = CTL_QUEUESMAX, .procname = "queues_max", .data = &queues_max, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec, }, { .ctl_name = CTL_MSGMAX, .procname = "msg_max", .data = &msg_max, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec_minmax, .extra1 = &msg_max_limit_min, .extra2 = &msg_max_limit_max, }, { .ctl_name = CTL_MSGSIZEMAX, .procname = "msgsize_max", .data = &msgsize_max, .maxlen = sizeof(int), .mode = 0644, .proc_handler = &proc_dointvec_minmax, .extra1 = &msg_maxsize_limit_min, .extra2 = &msg_maxsize_limit_max, }, { .ctl_name = 0 } }; static ctl_table mq_sysctl_dir[] = { { .ctl_name = FS_MQUEUE, .procname = "mqueue", .mode = 0555, .child = mq_sysctls, }, { .ctl_name = 0 } }; static ctl_table mq_sysctl_root[] = { { .ctl_name = CTL_FS, .procname = "fs", .mode = 0555, .child = mq_sysctl_dir, }, { .ctl_name = 0 } }; 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, NULL); if (mqueue_inode_cachep == NULL) return -ENOMEM; /* ignore failues - they are not fatal */ mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0); error = register_filesystem(&mqueue_fs_type); if (error) goto out_sysctl; if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) { error = PTR_ERR(mqueue_mnt); goto out_filesystem; } /* internal initialization - not common for vfs */ queues_count = 0; spin_lock_init(&mq_lock); return 0; out_filesystem: unregister_filesystem(&mqueue_fs_type); out_sysctl: if (mq_sysctl_table) unregister_sysctl_table(mq_sysctl_table); if (kmem_cache_destroy(mqueue_inode_cachep)) { printk(KERN_INFO "mqueue_inode_cache: not all structures were freed\n"); } return error; } __initcall(init_mqueue_fs);