linux-kernel - [GIT PULL] apparmor: Final fix for v6.7-rc8

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Date: Wed, 3 Jan 2024 12:26:25 -0800
From: John Johansen <john.johansen@...onical.com>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: LKLM <linux-kernel@...r.kernel.org>,
 "open list:SECURITY SUBSYSTEM" <linux-security-module@...r.kernel.org>
Subject: [GIT PULL] apparmor: Final fix for v6.7-rc8

Linus,

Please pull the following fix for the apparmor move_mount regression

- detect that the source mount is not in the namespace and if it
   isn't don't use it as a source path match. This prevent apparmor
   from applying the attach_disconnected flag to move_mount() source
   which prevents detached mounts from appearing as / when applying
   mount mediation, which is not only incorrect but could result in
   bad policy being generated.


The following changes since commit 610a9b8f49fbcf1100716370d3b5f6f884a2835a:

   Linux 6.7-rc8 (2023-12-31 12:51:25 -0800)

are available in the Git repository at:

   git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor tags/apparmor-pr-2024-01-03

for you to fetch changes up to 8026e40608b4d552216d2a818ca7080a4264bb44:

   apparmor: Fix move_mount mediation by detecting if source is detached (2024-01-03 12:10:29 -0800)

----------------------------------------------------------------
+ Bug Fix
   - Fix move_mount mediation regression when source is detached

----------------------------------------------------------------
John Johansen (1):
       apparmor: Fix move_mount mediation by detecting if source is detached

  security/apparmor/apparmorfs.c | 1 +
  security/apparmor/mount.c      | 4 ++++
  2 files changed, 5 insertions(+)
---------------------------
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 38650e52ef57..2d9f2a4b4519 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -2373,6 +2373,7 @@ static struct aa_sfs_entry aa_sfs_entry_policy[] = {
  
  static struct aa_sfs_entry aa_sfs_entry_mount[] = {
  	AA_SFS_FILE_STRING("mask", "mount umount pivot_root"),
+	AA_SFS_FILE_STRING("move_mount", "detached"),
  	{ }
  };
  
diff --git a/security/apparmor/mount.c b/security/apparmor/mount.c
index fb30204c761a..49fe8da6fea4 100644
--- a/security/apparmor/mount.c
+++ b/security/apparmor/mount.c
@@ -499,6 +499,10 @@ int aa_move_mount(const struct cred *subj_cred,
  	error = -ENOMEM;
  	if (!to_buffer || !from_buffer)
  		goto out;
+
+	if (!our_mnt(from_path->mnt))
+		/* moving a mount detached from the namespace */
+		from_path = NULL;
  	error = fn_for_each_confined(label, profile,
  			match_mnt(subj_cred, profile, to_path, to_buffer,
  				  from_path, from_buffer,