make fanotify_read() restartable across signals

[net-next-2.6.git] / fs / notify / fanotify / fanotify_user.c

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 5ed8e58d7bfc316f44c056e6208c3787dbc5f445..063224812b7e607879bffeedd5b90f9c4967346f 100644 (file)
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -16,6 +16,10 @@
 
 #include <asm/ioctls.h>
 
+#define FANOTIFY_DEFAULT_MAX_EVENTS    16384
+#define FANOTIFY_DEFAULT_MAX_MARKS     8192
+#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
+
 extern const struct fsnotify_ops fanotify_fsnotify_ops;
 
 static struct kmem_cache *fanotify_mark_cache __read_mostly;
@@ -326,7 +330,7 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
                ret = -EAGAIN;
                if (file->f_flags & O_NONBLOCK)
                        break;
-               ret = -EINTR;
+               ret = -ERESTARTSYS;
                if (signal_pending(current))
                        break;
 
@@ -372,11 +376,10 @@ static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t
 static int fanotify_release(struct inode *ignored, struct file *file)
 {
        struct fsnotify_group *group = file->private_data;
-       struct fanotify_response_event *re, *lre;
-
-       pr_debug("%s: file=%p group=%p\n", __func__, file, group);
 
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
+       struct fanotify_response_event *re, *lre;
+
        mutex_lock(&group->fanotify_data.access_mutex);
 
        group->fanotify_data.bypass_perm = true;
@@ -433,6 +436,7 @@ static const struct file_operations fanotify_fops = {
        .release        = fanotify_release,
        .unlocked_ioctl = fanotify_ioctl,
        .compat_ioctl   = fanotify_ioctl,
+       .llseek         = noop_llseek,
 };
 
 static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
@@ -553,18 +557,24 @@ static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
                                       __u32 mask,
                                       unsigned int flags)
 {
-       __u32 oldmask;
+       __u32 oldmask = -1;
 
        spin_lock(&fsn_mark->lock);
        if (!(flags & FAN_MARK_IGNORED_MASK)) {
                oldmask = fsn_mark->mask;
                fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
        } else {
-               oldmask = fsn_mark->ignored_mask;
-               fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask | mask));
+               __u32 tmask = fsn_mark->ignored_mask | mask;
+               fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
                if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
                        fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
        }
+
+       if (!(flags & FAN_MARK_ONDIR)) {
+               __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR;
+               fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
+       }
+
        spin_unlock(&fsn_mark->lock);
 
        return mask & ~oldmask;
@@ -581,6 +591,9 @@ static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
        if (!fsn_mark) {
                int ret;
 
+               if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
+                       return -ENOSPC;
+
                fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
                if (!fsn_mark)
                        return -ENOMEM;
@@ -609,10 +622,23 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
 
        pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
 
+       /*
+        * If some other task has this inode open for write we should not add
+        * an ignored mark, unless that ignored mark is supposed to survive
+        * modification changes anyway.
+        */
+       if ((flags & FAN_MARK_IGNORED_MASK) &&
+           !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
+           (atomic_read(&inode->i_writecount) > 0))
+               return 0;
+
        fsn_mark = fsnotify_find_inode_mark(group, inode);
        if (!fsn_mark) {
                int ret;
 
+               if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
+                       return -ENOSPC;
+
                fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
                if (!fsn_mark)
                        return -ENOMEM;
@@ -636,6 +662,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 {
        struct fsnotify_group *group;
        int f_flags, fd;
+       struct user_struct *user;
 
        pr_debug("%s: flags=%d event_f_flags=%d\n",
                __func__, flags, event_f_flags);
@@ -646,6 +673,12 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
        if (flags & ~FAN_ALL_INIT_FLAGS)
                return -EINVAL;
 
+       user = get_current_user();
+       if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
+               free_uid(user);
+               return -EMFILE;
+       }
+
        f_flags = O_RDWR | FMODE_NONOTIFY;
        if (flags & FAN_CLOEXEC)
                f_flags |= O_CLOEXEC;
@@ -657,12 +690,47 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
        if (IS_ERR(group))
                return PTR_ERR(group);
 
+       group->fanotify_data.user = user;
+       atomic_inc(&user->fanotify_listeners);
+
        group->fanotify_data.f_flags = event_f_flags;
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
        mutex_init(&group->fanotify_data.access_mutex);
        init_waitqueue_head(&group->fanotify_data.access_waitq);
        INIT_LIST_HEAD(&group->fanotify_data.access_list);
 #endif
+       switch (flags & FAN_ALL_CLASS_BITS) {
+       case FAN_CLASS_NOTIF:
+               group->priority = FS_PRIO_0;
+               break;
+       case FAN_CLASS_CONTENT:
+               group->priority = FS_PRIO_1;
+               break;
+       case FAN_CLASS_PRE_CONTENT:
+               group->priority = FS_PRIO_2;
+               break;
+       default:
+               fd = -EINVAL;
+               goto out_put_group;
+       }
+
+       if (flags & FAN_UNLIMITED_QUEUE) {
+               fd = -EPERM;
+               if (!capable(CAP_SYS_ADMIN))
+                       goto out_put_group;
+               group->max_events = UINT_MAX;
+       } else {
+               group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
+       }
+
+       if (flags & FAN_UNLIMITED_MARKS) {
+               fd = -EPERM;
+               if (!capable(CAP_SYS_ADMIN))
+                       goto out_put_group;
+               group->fanotify_data.max_marks = UINT_MAX;
+       } else {
+               group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
+       }
 
        fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
        if (fd < 0)
@@ -703,6 +771,12 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
        default:
                return -EINVAL;
        }
+
+       if (mask & FAN_ONDIR) {
+               flags |= FAN_MARK_ONDIR;
+               mask &= ~FAN_ONDIR;
+       }
+
 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
        if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
 #else
@@ -718,6 +792,16 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
        ret = -EINVAL;
        if (unlikely(filp->f_op != &fanotify_fops))
                goto fput_and_out;
+       group = filp->private_data;
+
+       /*
+        * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF.  These are not
+        * allowed to set permissions events.
+        */
+       ret = -EINVAL;
+       if (mask & FAN_ALL_PERM_EVENTS &&
+           group->priority == FS_PRIO_0)
+               goto fput_and_out;
 
        ret = fanotify_find_path(dfd, pathname, &path, flags);
        if (ret)
@@ -728,7 +812,6 @@ SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
                inode = path.dentry->d_inode;
        else
                mnt = path.mnt;
-       group = filp->private_data;
 
        /* create/update an inode mark */
        switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {