When an NFSv4 client performs a mount operation, it first mounts the
NFSv4 root and then does path walk to the exported path and performs a
submount on that, cloning the security mount options from the root's
superblock to the submount's superblock in the process.
Unless the NFS server has an explicit fsid=0 export with the
"security_label" option, the NFSv4 root superblock will not have
SBLABEL_MNT set, and neither will the submount superblock after cloning
the security mount options. As a result, setxattr's of security labels
over NFSv4.2 will fail.
Allowing the NFSv4 client to override the SECURITY_LSM_NATIVE_LABELS
flag on an initialized superblock will ensure that SBLABEL_MNT is set
when the client traverses from an exported path without the
"security_label" option to one with the "security_label" option.
Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx>
---
security/selinux/hooks.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e67a526..366ab86 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -730,7 +730,7 @@ static int selinux_set_mnt_opts(struct super_block *sb,
* will be used for both mounts)
*/
if ((sbsec->flags & SE_SBINITIALIZED) && (sb->s_type->fs_flags & FS_BINARY_MOUNTDATA)
- && (num_opts == 0))
+ && (num_opts == 0) && !(kern_flags & SECURITY_LSM_NATIVE_LABELS))
goto out;
root_isec = backing_inode_security_novalidate(root);
@@ -797,7 +797,7 @@ static int selinux_set_mnt_opts(struct super_block *sb,
}
}
- if (sbsec->flags & SE_SBINITIALIZED) {
+ if (sbsec->flags & SE_SBINITIALIZED && !(kern_flags & SECURITY_LSM_NATIVE_LABELS)) {
/* previously mounted with options, but not on this attempt? */
if ((sbsec->flags & SE_MNTMASK) && !num_opts)
goto out_double_mount;
--
2.9.3
--
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