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| author | Ondrej Mosnacek <omosnace@redhat.com> | 2023-09-11 16:23:58 +0200 |
|---|---|---|
| committer | Paul Moore <paul@paul-moore.com> | 2023-09-12 17:31:08 -0400 |
| commit | ccf1dab96be4caed7c5235b1cfdb606ac161b996 (patch) | |
| tree | 60271c741ee17f9f3758f0a7b9a5cfefded0ad09 /security | |
| parent | 0bb80ecc33a8fb5a682236443c1e740d5c917d1d (diff) | |
| download | linux-stable-ccf1dab96be4caed7c5235b1cfdb606ac161b996.tar.gz linux-stable-ccf1dab96be4caed7c5235b1cfdb606ac161b996.tar.bz2 linux-stable-ccf1dab96be4caed7c5235b1cfdb606ac161b996.zip | |
selinux: fix handling of empty opts in selinux_fs_context_submount()
selinux_set_mnt_opts() relies on the fact that the mount options pointer
is always NULL when all options are unset (specifically in its
!selinux_initialized() branch. However, the new
selinux_fs_context_submount() hook breaks this rule by allocating a new
structure even if no options are set. That causes any submount created
before a SELinux policy is loaded to be rejected in
selinux_set_mnt_opts().
Fix this by making selinux_fs_context_submount() leave fc->security
set to NULL when there are no options to be copied from the reference
superblock.
Cc: <stable@vger.kernel.org>
Reported-by: Adam Williamson <awilliam@redhat.com>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2236345
Fixes: d80a8f1b58c2 ("vfs, security: Fix automount superblock LSM init problem, preventing NFS sb sharing")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security')
| -rw-r--r-- | security/selinux/hooks.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 10350534de6d..2aa0e219d721 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2775,14 +2775,20 @@ static int selinux_umount(struct vfsmount *mnt, int flags) static int selinux_fs_context_submount(struct fs_context *fc, struct super_block *reference) { - const struct superblock_security_struct *sbsec; + const struct superblock_security_struct *sbsec = selinux_superblock(reference); struct selinux_mnt_opts *opts; + /* + * Ensure that fc->security remains NULL when no options are set + * as expected by selinux_set_mnt_opts(). + */ + if (!(sbsec->flags & (FSCONTEXT_MNT|CONTEXT_MNT|DEFCONTEXT_MNT))) + return 0; + opts = kzalloc(sizeof(*opts), GFP_KERNEL); if (!opts) return -ENOMEM; - sbsec = selinux_superblock(reference); if (sbsec->flags & FSCONTEXT_MNT) opts->fscontext_sid = sbsec->sid; if (sbsec->flags & CONTEXT_MNT) |