4.19-stable review patch. If anyone has any objections, please let me know.
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From: J. Bruce Fields bfields@redhat.com
commit 3815a245b50124f0865415dcb606a034e97494d4 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- security/selinux/hooks.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1034,8 +1034,11 @@ static int selinux_sb_clone_mnt_opts(con 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);