diff options
| -rw-r--r-- | fs/notify/fanotify/fanotify_user.c | 61 | ||||
| -rw-r--r-- | include/linux/fanotify.h | 2 |
2 files changed, 61 insertions, 2 deletions
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index cd82dd713c91..1638c171ca82 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -17,6 +17,8 @@ #include <linux/compat.h> #include <linux/sched/signal.h> #include <linux/memcontrol.h> +#include <linux/statfs.h> +#include <linux/exportfs.h> #include <asm/ioctls.h> @@ -768,6 +770,10 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) return -EINVAL; } + if ((flags & FAN_REPORT_FID) && + (flags & FANOTIFY_CLASS_BITS) != FAN_CLASS_NOTIF) + return -EINVAL; + user = get_current_user(); if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { free_uid(user); @@ -854,6 +860,52 @@ out_destroy_group: return fd; } +/* Check if filesystem can encode a unique fid */ +static int fanotify_test_fid(struct path *path) +{ + struct kstatfs stat, root_stat; + struct path root = { + .mnt = path->mnt, + .dentry = path->dentry->d_sb->s_root, + }; + int err; + + /* + * Make sure path is not in filesystem with zero fsid (e.g. tmpfs). + */ + err = vfs_statfs(path, &stat); + if (err) + return err; + + if (!stat.f_fsid.val[0] && !stat.f_fsid.val[1]) + return -ENODEV; + + /* + * Make sure path is not inside a filesystem subvolume (e.g. btrfs) + * which uses a different fsid than sb root. + */ + err = vfs_statfs(&root, &root_stat); + if (err) + return err; + + if (root_stat.f_fsid.val[0] != stat.f_fsid.val[0] || + root_stat.f_fsid.val[1] != stat.f_fsid.val[1]) + return -EXDEV; + + /* + * We need to make sure that the file system supports at least + * encoding a file handle so user can use name_to_handle_at() to + * compare fid returned with event to the file handle of watched + * objects. However, name_to_handle_at() requires that the + * filesystem also supports decoding file handles. + */ + if (!path->dentry->d_sb->s_export_op || + !path->dentry->d_sb->s_export_op->fh_to_dentry) + return -EOPNOTSUPP; + + return 0; +} + static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, int dfd, const char __user *pathname) { @@ -939,6 +991,12 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, if (ret) goto fput_and_out; + if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) { + ret = fanotify_test_fid(&path); + if (ret) + goto path_put_and_out; + } + /* inode held in place by reference to path; group by fget on fd */ if (mark_type == FAN_MARK_INODE) inode = path.dentry->d_inode; @@ -967,6 +1025,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, ret = -EINVAL; } +path_put_and_out: path_put(&path); fput_and_out: fdput(f); @@ -1003,7 +1062,7 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark, */ static int __init fanotify_user_setup(void) { - BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 7); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 8); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9); fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index 9e2142795335..f59be967f72b 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -19,7 +19,7 @@ FAN_CLASS_PRE_CONTENT) #define FANOTIFY_INIT_FLAGS (FANOTIFY_CLASS_BITS | \ - FAN_REPORT_TID | \ + FAN_REPORT_TID | FAN_REPORT_FID | \ FAN_CLOEXEC | FAN_NONBLOCK | \ FAN_UNLIMITED_QUEUE | FAN_UNLIMITED_MARKS) |