Commit 36c79551 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'fsnotify_for_v5.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 

Pull fsnotify fixes from Jan Kara:
 "A fix for permission checking with fanotify unpriviledged groups.

  Also there's a small update in MAINTAINERS file for fanotify"

* tag 'fsnotify_for_v5.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fanotify: fix permission model of unprivileged group
  MAINTAINERS: Add Matthew Bobrowski as a reviewer
parents 8124c8a6 a8b98c80

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -6945,6 +6945,7 @@ F: net/core/failover.c 
FANOTIFY

M:	Jan Kara <jack@suse.cz>

R:	Amir Goldstein <amir73il@gmail.com>

R:	Matthew Bobrowski <repnop@google.com>

L:	linux-fsdevel@vger.kernel.org

S:	Maintained

F:	fs/notify/fanotify/

fs/notify/fanotify/fanotify_user.c

+24 −6
Original line number Diff line number Diff line
@@ -424,11 +424,18 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, 
	 * events generated by the listener process itself, without disclosing

	 * the pids of other processes.

	 */

	if (!capable(CAP_SYS_ADMIN) &&

	if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&

	    task_tgid(current) != event->pid)

		metadata.pid = 0;



	if (path && path->mnt && path->dentry) {

	/*

	 * For now, fid mode is required for an unprivileged listener and

	 * fid mode does not report fd in events.  Keep this check anyway

	 * for safety in case fid mode requirement is relaxed in the future

	 * to allow unprivileged listener to get events with no fd and no fid.

	 */

	if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&

	    path && path->mnt && path->dentry) {

		fd = create_fd(group, path, &f);

		if (fd < 0)

			return fd;
@@ -1040,6 +1047,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
	int f_flags, fd;

	unsigned int fid_mode = flags & FANOTIFY_FID_BITS;

	unsigned int class = flags & FANOTIFY_CLASS_BITS;

	unsigned int internal_flags = 0;



	pr_debug("%s: flags=%x event_f_flags=%x\n",

		 __func__, flags, event_f_flags);
@@ -1053,6 +1061,13 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
		 */

		if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode)

			return -EPERM;



		/*

		 * Setting the internal flag FANOTIFY_UNPRIV on the group

		 * prevents setting mount/filesystem marks on this group and

		 * prevents reporting pid and open fd in events.

		 */

		internal_flags |= FANOTIFY_UNPRIV;

	}



#ifdef CONFIG_AUDITSYSCALL
@@ -1105,7 +1120,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) 
		goto out_destroy_group;

	}



	group->fanotify_data.flags = flags;

	group->fanotify_data.flags = flags | internal_flags;

	group->memcg = get_mem_cgroup_from_mm(current->mm);



	group->fanotify_data.merge_hash = fanotify_alloc_merge_hash();
@@ -1305,11 +1320,13 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, 
	group = f.file->private_data;



	/*

	 * An unprivileged user is not allowed to watch a mount point nor

	 * a filesystem.

	 * An unprivileged user is not allowed to setup mount nor filesystem

	 * marks.  This also includes setting up such marks by a group that

	 * was initialized by an unprivileged user.

	 */

	ret = -EPERM;

	if (!capable(CAP_SYS_ADMIN) &&

	if ((!capable(CAP_SYS_ADMIN) ||

	     FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) &&

	    mark_type != FAN_MARK_INODE)

		goto fput_and_out;
@@ -1460,6 +1477,7 @@ static int __init fanotify_user_setup(void) 
	max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS,

				     FANOTIFY_DEFAULT_MAX_USER_MARKS);



	BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS);

	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 10);

	BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9);

fs/notify/fdinfo.c

+1 −1
Original line number Diff line number Diff line
@@ -144,7 +144,7 @@ void fanotify_show_fdinfo(struct seq_file *m, struct file *f) 
	struct fsnotify_group *group = f->private_data;



	seq_printf(m, "fanotify flags:%x event-flags:%x\n",

		   group->fanotify_data.flags,

		   group->fanotify_data.flags & FANOTIFY_INIT_FLAGS,

		   group->fanotify_data.f_flags);



	show_fdinfo(m, f, fanotify_fdinfo);

include/linux/fanotify.h

+4 −0
Original line number Diff line number Diff line
@@ -51,6 +51,10 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */ 
#define FANOTIFY_INIT_FLAGS	(FANOTIFY_ADMIN_INIT_FLAGS | \

				 FANOTIFY_USER_INIT_FLAGS)



/* Internal group flags */

#define FANOTIFY_UNPRIV		0x80000000

#define FANOTIFY_INTERNAL_GROUP_FLAGS	(FANOTIFY_UNPRIV)



#define FANOTIFY_MARK_TYPE_BITS	(FAN_MARK_INODE | FAN_MARK_MOUNT | \

				 FAN_MARK_FILESYSTEM)