NetLabel: make netlbl_lsm_secattr struct easier/quicker to understand

The existing netlbl_lsm_secattr struct required the LSM to check all of the
fields to determine if any security attributes were present resulting in a lot
of work in the common case of no attributes.  This patch adds a 'flags' field
which is used to indicate which attributes are present in the structure; this
should allow the LSM to do a quick comparison to determine if the structure
holds any security attributes.

Example:

 if (netlbl_lsm_secattr->flags)
	/* security attributes present */
 else
	/* NO security attributes present */

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 14 insertions, 8 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 095038ad72a4..f0a0785047fe 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -319,6 +319,7 @@ static int cipso_v4_cache_check(const unsigned char *key,
                         entry->activity += 1;
                         atomic_inc(&entry->lsm_data->refcount);
                         secattr->cache = entry->lsm_data;
+                        secattr->flags |= NETLBL_SECATTR_CACHE;
                         if (prev_entry == NULL) {
                                 spin_unlock_bh(&cipso_v4_cache[bkt].lock);
                                 return 0;
@@ -991,12 +992,15 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
                                unsigned char **buffer,
                                u32 *buffer_len)
 {
-        int ret_val = -EPERM;
+        int ret_val;
         unsigned char *buf = NULL;
         u32 buf_len;
         u32 level;
 
-        if (secattr->mls_cat) {
+        if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
+                return -EPERM;
+
+        if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
                 buf = kzalloc(CIPSO_V4_HDR_LEN + 4 + CIPSO_V4_TAG1_CAT_LEN,
                               GFP_ATOMIC);
                 if (buf == NULL)
@@ -1013,10 +1017,10 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
                 /* This will send packets using the "optimized" format when
                  * possibile as specified in  section 3.4.2.6 of the
                  * CIPSO draft. */
-                if (cipso_v4_rbm_optfmt && (ret_val > 0 && ret_val < 10))
-                        ret_val = 10;
-
-                buf_len = 4 + ret_val;
+                if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)
+                        buf_len = 14;
+                else
+                        buf_len = 4 + ret_val;
         } else {
                 buf = kzalloc(CIPSO_V4_HDR_LEN + 4, GFP_ATOMIC);
                 if (buf == NULL)
@@ -1070,7 +1074,7 @@ static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
         if (ret_val != 0)
                 return ret_val;
         secattr->mls_lvl = level;
-        secattr->mls_lvl_vld = 1;
+        secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
         if (tag_len > 4) {
                 switch (doi_def->type) {
@@ -1094,8 +1098,10 @@ static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
                 if (ret_val < 0) {
                         kfree(secattr->mls_cat);
                         return ret_val;
+                } else if (ret_val > 0) {
+                        secattr->mls_cat_len = ret_val;
+                        secattr->flags |= NETLBL_SECATTR_MLS_CAT;
                 }
-                secattr->mls_cat_len = ret_val;
         }
 
         return 0;