From 3815a245b50124f0865415dcb606a034e97494d4 Mon Sep 17 00:00:00 2001
From: "J. Bruce Fields" <bfields@redhat.com>
Date: Tue, 5 Mar 2019 16:17:58 -0500
Subject: [PATCH] security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused
superblock
In the case when we're reusing a superblock, selinux_sb_clone_mnt_opts()
fails to set set_kern_flags, with the result that
nfs_clone_sb_security() incorrectly clears NFS_CAP_SECURITY_LABEL.
The result is that if you mount the same NFS filesystem twice, NFS
security labels are turned off, even if they would work fine if you
mounted the filesystem only once.
("fixes" may be not exactly the right tag, it may be more like
"fixed-other-cases-but-missed-this-one".)
Cc: Scott Mayhew <smayhew@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 0b4d3452b8b4 "security/selinux: allow security_sb_clone_mnt_opts..."
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
security/selinux/hooks.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 3745922c71329..0fe5ed8c33a0a 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -981,8 +981,11 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb,
BUG_ON(!(oldsbsec->flags & SE_SBINITIALIZED));
/* if fs is reusing a sb, make sure that the contexts match */
- if (newsbsec->flags & SE_SBINITIALIZED)
+ if (newsbsec->flags & SE_SBINITIALIZED) {
+ if ((kern_flags & SECURITY_LSM_NATIVE_LABELS) && !set_context)
+ *set_kern_flags |= SECURITY_LSM_NATIVE_LABELS;
return selinux_cmp_sb_context(oldsb, newsb);
+ }
mutex_lock(&newsbsec->lock);
--
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