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linux/ipc/mqueue.c
Alexey Dobriyan b87221de6a const: mark remaining super_operations const 
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-22 07:17:24 -07:00

1304 lines
31 KiB
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/*
* 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/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/ima.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
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;
struct pid* 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 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;
}
static struct inode *mqueue_get_inode(struct super_block *sb,
struct ipc_namespace *ipc_ns, int mode,
struct mq_attr *attr)
{
struct user_struct *u = current_user();
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_mtime = inode->i_ctime = inode->i_atime =
CURRENT_TIME;
if (S_ISREG(mode)) {
struct mqueue_inode_info *info;
struct task_struct *p = current;
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 = NULL;
info->qsize = 0;
info->user = NULL; /* set when all is ok */
memset(&info->attr, 0, sizeof(info->attr));
info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
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)) {
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:
make_bad_inode(inode);
iput(inode);
return NULL;
}
static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
struct ipc_namespace *ns = data;
int error = 0;
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 (!inode) {
error = -ENOMEM;
goto out;
}
sb->s_root = d_alloc_root(inode);
if (!sb->s_root) {
iput(inode);
error = -ENOMEM;
}
out:
return error;
}
static int mqueue_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt)
{
if (!(flags & MS_KERNMOUNT))
data = current->nsproxy->ipc_ns;
return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
}
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_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;
struct ipc_namespace *ipc_ns;
if (S_ISDIR(inode->i_mode)) {
clear_inode(inode);
return;
}
ipc_ns = get_ns_from_inode(inode);
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;
/*
* 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,
int mode, struct nameidata *nd)
{
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 (!inode) {
error = -ENOMEM;
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 = dentry->d_inode;
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(filp->f_path.dentry->d_inode);
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;
filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->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(filp->f_path.dentry->d_inode);
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(filp->f_path.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 = task_tgid_nr_ns(current,
ns_of_pid(info->notify_owner));
sig_i.si_uid = current_uid();
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);
info->notify_owner = NULL;
}
wake_up(&info->wait_q);
}
static long prepare_timeout(struct timespec *p)
{
struct timespec nowts;
long timeout;
if (p) {
if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
|| p->tv_nsec >= NSEC_PER_SEC))
return -EINVAL;
nowts = CURRENT_TIME;
/* first subtract as jiffies can't be too big */
p->tv_sec -= nowts.tv_sec;
if (p->tv_nsec < nowts.tv_nsec) {
p->tv_nsec += NSEC_PER_SEC;
p->tv_sec--;
}
p->tv_nsec -= nowts.tv_nsec;
if (p->tv_sec < 0)
return 0;
timeout = timespec_to_jiffies(p) + 1;
} else
return MAX_SCHEDULE_TIMEOUT;
return timeout;
}
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);
info->notify_owner = NULL;
}
static int mq_attr_ok(struct ipc_namespace *ipc_ns, 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 > ipc_ns->mq_msg_max ||
attr->mq_msgsize > ipc_ns->mq_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 ipc_namespace *ipc_ns, struct dentry *dir,
struct dentry *dentry, int oflag, mode_t mode,
struct mq_attr *attr)
{
const struct cred *cred = current_cred();
struct file *result;
int ret;
if (attr) {
ret = -EINVAL;
if (!mq_attr_ok(ipc_ns, attr))
goto out;
/* store for use during create */
dentry->d_fsdata = attr;
}
mode &= ~current_umask();
ret = mnt_want_write(ipc_ns->mq_mnt);
if (ret)
goto out;
ret = vfs_create(dir->d_inode, dentry, mode, NULL);
dentry->d_fsdata = NULL;
if (ret)
goto out_drop_write;
result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
/*
* dentry_open() took a persistent mnt_want_write(),
* so we can now drop this one.
*/
mnt_drop_write(ipc_ns->mq_mnt);
return result;
out_drop_write:
mnt_drop_write(ipc_ns->mq_mnt);
out:
dput(dentry);
mntput(ipc_ns->mq_mnt);
return ERR_PTR(ret);
}
/* Opens existing queue */
static struct file *do_open(struct ipc_namespace *ipc_ns,
struct dentry *dentry, int oflag)
{
const struct cred *cred = current_cred();
static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
MAY_READ | MAY_WRITE };
if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
dput(dentry);
mntput(ipc_ns->mq_mnt);
return ERR_PTR(-EINVAL);
}
if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
dput(dentry);
mntput(ipc_ns->mq_mnt);
return ERR_PTR(-EACCES);
}
return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
}
SYSCALL_DEFINE4(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;
struct mq_attr attr;
int fd, error;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
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;
mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
if (IS_ERR(dentry)) {
error = PTR_ERR(dentry);
goto out_err;
}
mntget(ipc_ns->mq_mnt);
if (oflag & O_CREAT) {
if (dentry->d_inode) { /* entry already exists */
audit_inode(name, dentry);
error = -EEXIST;
if (oflag & O_EXCL)
goto out;
filp = do_open(ipc_ns, dentry, oflag);
} else {
filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
dentry, oflag, mode,
u_attr ? &attr : NULL);
}
} else {
error = -ENOENT;
if (!dentry->d_inode)
goto out;
audit_inode(name, dentry);
filp = do_open(ipc_ns, dentry, oflag);
}
if (IS_ERR(filp)) {
error = PTR_ERR(filp);
goto out_putfd;
}
ima_counts_get(filp);
fd_install(fd, filp);
goto out_upsem;
out:
dput(dentry);
mntput(ipc_ns->mq_mnt);
out_putfd:
put_unused_fd(fd);
out_err:
fd = error;
out_upsem:
mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
out_putname:
putname(name);
return fd;
}
SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
{
int err;
char *name;
struct dentry *dentry;
struct inode *inode = NULL;
struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
name = getname(u_name);
if (IS_ERR(name))
return PTR_ERR(name);
mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
I_MUTEX_PARENT);
dentry = lookup_one_len(name, ipc_ns->mq_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 = mnt_want_write(ipc_ns->mq_mnt);
if (err)
goto out_err;
err = vfs_unlink(dentry->d_parent->d_inode, dentry);
mnt_drop_write(ipc_ns->mq_mnt);
out_err:
dput(dentry);
out_unlock:
mutex_unlock(&ipc_ns->mq_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 for 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;
}
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 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;
struct timespec ts, *p = NULL;
long timeout;
int ret;
if (u_abs_timeout) {
if (copy_from_user(&ts, u_abs_timeout,
sizeof(struct timespec)))
return -EFAULT;
p = &ts;
}
if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
return -EINVAL;
audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
timeout = prepare_timeout(p);
ret = -EBADF;
filp = fget(mqdes);
if (unlikely(!filp))
goto out;
inode = filp->f_path.dentry->d_inode;
if (unlikely(filp->f_op != &mqueue_file_operations))
goto out_fput;
info = MQUEUE_I(inode);
audit_inode(NULL, filp->f_path.dentry);
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;
}
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)
{
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;
struct timespec ts, *p = NULL;
if (u_abs_timeout) {
if (copy_from_user(&ts, u_abs_timeout,
sizeof(struct timespec)))
return -EFAULT;
p = &ts;
}
audit_mq_sendrecv(mqdes, msg_len, 0, p);
timeout = prepare_timeout(p);
ret = -EBADF;
filp = fget(mqdes);
if (unlikely(!filp))
goto out;
inode = filp->f_path.dentry->d_inode;
if (unlikely(filp->f_op != &mqueue_file_operations))
goto out_fput;
info = MQUEUE_I(inode);
audit_inode(NULL, filp->f_path.dentry);
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.
*/
SYSCALL_DEFINE2(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;
if (u_notification) {
if (copy_from_user(&notification, u_notification,
sizeof(struct sigevent)))
return -EFAULT;
}
audit_mq_notify(mqdes, u_notification ? &notification : 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);
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;
}
timeo = MAX_SCHEDULE_TIMEOUT;
ret = netlink_attachskb(sock, nc, &timeo, 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_path.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 == 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));
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;
}
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 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_path.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) {
audit_mq_getsetattr(mqdes, &mqstat);
spin_lock(&filp->f_lock);
if (mqstat.mq_flags & O_NONBLOCK)
filp->f_flags |= O_NONBLOCK;
else
filp->f_flags &= ~O_NONBLOCK;
spin_unlock(&filp->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:
fput(filp);
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,
};
static const 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,
};
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_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)
{
mntput(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 failues - 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);
init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
if (IS_ERR(init_ipc_ns.mq_mnt)) {
error = PTR_ERR(init_ipc_ns.mq_mnt);
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;
}
__initcall(init_mqueue_fs);
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