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authorOndrej Mosnacek <omosnace@redhat.com>2023-09-11 16:23:58 +0200
committerPaul Moore <paul@paul-moore.com>2023-09-12 23:31:08 +0200
commitccf1dab96be4caed7c5235b1cfdb606ac161b996 (patch)
tree60271c741ee17f9f3758f0a7b9a5cfefded0ad09 /security
parentLinux 6.6-rc1 (diff)
downloadlinux-ccf1dab96be4caed7c5235b1cfdb606ac161b996.tar.xz
linux-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.c10
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)