BACKPORT: Kernel threads excluded from smack checks

Adds an ignore case for kernel tasks,
so that they can access all resources.

Since kernel worker threads are spawned with
floor label, they are severely restricted by
Smack policy. It is not an issue without onlycap,
as these processes also run with root,
so CAP_MAC_OVERRIDE kicks in. But with onlycap
turned on, there is no way to change the label
for these processes.

Signed-off-by: Roman Kubiak <r.kubiak@samsung.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
(cherry-picked from upstream 41a2d5751616e38d1e293e3cb35a6e2bc7a03473)

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index 00f6b38bffbde4546c51c929f1ad7ffb8c669f28..bc1053fb5d1d062a165b0b91c6553428aab653cf 100644 (file)
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -639,6 +639,12 @@ int smack_privileged(int cap)
        struct smack_known *skp = smk_of_current();
        struct smack_onlycap *sop;
 
+       /*
+        * All kernel tasks are privileged
+        */
+       if (unlikely(current->flags & PF_KTHREAD))
+               return 1;
+
        if (!capable(cap))
                return 0;