selinux: Implement the watch_key security hook

Implement the watch_key security hook to make sure that a key grants the
caller View permission in order to set a watch on a key.

For the moment, the watch_devices security hook is left unimplemented as
it's not obvious what the object should be since the queue is global and
didn't previously exist.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 196acac..5b3191b 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6619,6 +6619,17 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
        *_buffer = context;
        return rc;
 }
+
+#ifdef CONFIG_KEY_NOTIFICATIONS
+static int selinux_watch_key(struct key *key)
+{
+       struct key_security_struct *ksec = key->security;
+       u32 sid = current_sid();
+
+       return avc_has_perm(&selinux_state,
+                           sid, ksec->sid, SECCLASS_KEY, KEY__VIEW, NULL);
+}
+#endif
 #endif
 
 #ifdef CONFIG_SECURITY_INFINIBAND
@@ -7134,6 +7145,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
        LSM_HOOK_INIT(key_free, selinux_key_free),
        LSM_HOOK_INIT(key_permission, selinux_key_permission),
        LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity),
+#ifdef CONFIG_KEY_NOTIFICATIONS
+       LSM_HOOK_INIT(watch_key, selinux_watch_key),
+#endif
 #endif
 
 #ifdef CONFIG_AUDIT