From 8026e40608b4d552216d2a818ca7080a4264bb44 Mon Sep 17 00:00:00 2001 From: John Johansen Date: Mon, 18 Dec 2023 01:10:03 -0800 Subject: [PATCH] apparmor: Fix move_mount mediation by detecting if source is detached Prevent move_mount from applying the attach_disconnected flag to move_mount(). This prevents detached mounts from appearing as / when applying mount mediation, which is not only incorrect but could result in bad policy being generated. Basic mount rules like allow mount, allow mount options=(move) -> /target/, will allow detached mounts, allowing older policy to continue to function. New policy gains the ability to specify `detached` as a source option allow mount detached -> /target/, In addition make sure support of move_mount is advertised as a feature to userspace so that applications that generate policy can respond to the addition. Note: this fixes mediation of move_mount when a detached mount is used, it does not fix the broader regression of apparmor mediation of mounts under the new mount api. Link: https://lore.kernel.org/all/68c166b8-5b4d-4612-8042-1dee3334385b@leemhuis.info/T/#mb35fdde37f999f08f0b02d58dc1bf4e6b65b8da2 Fixes: 157a3537d6bc ("apparmor: Fix regression in mount mediation") Reviewed-by: Georgia Garcia Signed-off-by: John Johansen --- 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,