NetLabel: Allow passing the LSM domain as a shared pointer

Smack doesn't have the need to create a private copy of the LSM "domain" when
setting NetLabel security attributes like SELinux, however, the current
NetLabel code requires a private copy of the LSM "domain".  This patches fixes
that by letting the LSM determine how it wants to pass the domain value.

 * NETLBL_SECATTR_DOMAIN_CPY
   The current behavior, NetLabel assumes that the domain value is a copy and
   frees it when done

 * NETLBL_SECATTR_DOMAIN
   New, Smack-friendly behavior, NetLabel assumes that the domain value is a
   reference to a string managed by the LSM and does not free it when done

Signed-off-by: Paul Moore <paul.moore@hp.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 4 deletions

diff --git a/include/net/netlabel.h b/include/net/netlabel.h
index 0ca67d73c7ad..5e53a85b5ca1 100644
--- a/include/net/netlabel.h
+++ b/include/net/netlabel.h
@@ -162,7 +162,7 @@ struct netlbl_lsm_secattr_catmap {
 
 /**
  * struct netlbl_lsm_secattr - NetLabel LSM security attributes
- * @flags: indicate which attributes are contained in this structure
+ * @flags: indicate structure attributes, see NETLBL_SECATTR_*
  * @type: indicate the NLTYPE of the attributes
  * @domain: the NetLabel LSM domain
  * @cache: NetLabel LSM specific cache
@@ -180,17 +180,22 @@ struct netlbl_lsm_secattr_catmap {
  * NetLabel itself when returning security attributes to the LSM.
  *
  */
+struct netlbl_lsm_secattr {
+        u32 flags;
+        /* bitmap values for 'flags' */
 #define NETLBL_SECATTR_NONE             0x00000000
 #define NETLBL_SECATTR_DOMAIN           0x00000001
+#define NETLBL_SECATTR_DOMAIN_CPY       (NETLBL_SECATTR_DOMAIN | \
+                                         NETLBL_SECATTR_FREE_DOMAIN)
 #define NETLBL_SECATTR_CACHE            0x00000002
 #define NETLBL_SECATTR_MLS_LVL          0x00000004
 #define NETLBL_SECATTR_MLS_CAT          0x00000008
 #define NETLBL_SECATTR_SECID            0x00000010
+        /* bitmap meta-values for 'flags' */
+#define NETLBL_SECATTR_FREE_DOMAIN      0x01000000
 #define NETLBL_SECATTR_CACHEABLE        (NETLBL_SECATTR_MLS_LVL | \
                                          NETLBL_SECATTR_MLS_CAT | \
                                          NETLBL_SECATTR_SECID)
-struct netlbl_lsm_secattr {
-        u32 flags;
         u32 type;
         char *domain;
         struct netlbl_lsm_cache *cache;
@@ -303,7 +308,8 @@ static inline void netlbl_secattr_init(struct netlbl_lsm_secattr *secattr)
  */
 static inline void netlbl_secattr_destroy(struct netlbl_lsm_secattr *secattr)
 {
-        kfree(secattr->domain);
+        if (secattr->flags & NETLBL_SECATTR_FREE_DOMAIN)
+                kfree(secattr->domain);
         if (secattr->flags & NETLBL_SECATTR_CACHE)
                 netlbl_secattr_cache_free(secattr->cache);
         if (secattr->flags & NETLBL_SECATTR_MLS_CAT)