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-rw-r--r--fs/notify/fanotify/fanotify_user.c22
-rw-r--r--fs/proc/root.c2
-rw-r--r--include/linux/fs.h1
3 files changed, 24 insertions, 1 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index a90bb19dcfa2..91006f47e420 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -920,6 +920,22 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
return 0;
}
+static int fanotify_events_supported(struct path *path, __u64 mask)
+{
+ /*
+ * Some filesystems such as 'proc' acquire unusual locks when opening
+ * files. For them fanotify permission events have high chances of
+ * deadlocking the system - open done when reporting fanotify event
+ * blocks on this "unusual" lock while another process holding the lock
+ * waits for fanotify permission event to be answered. Just disallow
+ * permission events for such filesystems.
+ */
+ if (mask & FANOTIFY_PERM_EVENTS &&
+ path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM)
+ return -EINVAL;
+ return 0;
+}
+
static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
int dfd, const char __user *pathname)
{
@@ -1018,6 +1034,12 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
if (ret)
goto fput_and_out;
+ if (flags & FAN_MARK_ADD) {
+ ret = fanotify_events_supported(&path, mask);
+ if (ret)
+ goto path_put_and_out;
+ }
+
if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
ret = fanotify_test_fid(&path, &__fsid);
if (ret)
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 8b145e7b9661..522199e9525e 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -211,7 +211,7 @@ static struct file_system_type proc_fs_type = {
.init_fs_context = proc_init_fs_context,
.parameters = &proc_fs_parameters,
.kill_sb = proc_kill_sb,
- .fs_flags = FS_USERNS_MOUNT,
+ .fs_flags = FS_USERNS_MOUNT | FS_DISALLOW_NOTIFY_PERM,
};
void __init proc_root_init(void)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f7fdfe93e25d..c7136c98b5ba 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2184,6 +2184,7 @@ struct file_system_type {
#define FS_BINARY_MOUNTDATA 2
#define FS_HAS_SUBTYPE 4
#define FS_USERNS_MOUNT 8 /* Can be mounted by userns root */
+#define FS_DISALLOW_NOTIFY_PERM 16 /* Disable fanotify permission events */
#define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() during rename() internally. */
int (*init_fs_context)(struct fs_context *);
const struct fs_parameter_description *parameters;