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>

4 files changed, 45 insertions, 19 deletions

diff --git a/include/net/netlabel.h b/include/net/netlabel.h
index 4e223aa25e5..d605d795401 100644
--- a/include/net/netlabel.h
+++ b/include/net/netlabel.h
@@ -111,11 +111,17 @@ struct netlbl_lsm_cache {
         void (*free) (const void *data);
         void *data;
 };
+#define NETLBL_SECATTR_NONE             0x00000000
+#define NETLBL_SECATTR_DOMAIN           0x00000001
+#define NETLBL_SECATTR_CACHE            0x00000002
+#define NETLBL_SECATTR_MLS_LVL          0x00000004
+#define NETLBL_SECATTR_MLS_CAT          0x00000008
 struct netlbl_lsm_secattr {
+        u32 flags;
+
         char *domain;
 
         u32 mls_lvl;
-        u32 mls_lvl_vld;
         unsigned char *mls_cat;
         size_t mls_cat_len;
 
@@ -174,7 +180,10 @@ static inline void netlbl_secattr_cache_free(struct netlbl_lsm_cache *cache)
  */
 static inline void netlbl_secattr_init(struct netlbl_lsm_secattr *secattr)
 {
-        memset(secattr, 0, sizeof(*secattr));
+        secattr->flags = 0;
+        secattr->domain = NULL;
+        secattr->mls_cat = NULL;
+        secattr->cache = NULL;
 }
 
 /**
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 095038ad72a..f0a0785047f 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;
diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
index ff971103fd0..da2f1975a04 100644
--- a/net/netlabel/netlabel_kapi.c
+++ b/net/netlabel/netlabel_kapi.c
@@ -62,6 +62,9 @@ int netlbl_socket_setattr(const struct socket *sock,
         int ret_val = -ENOENT;
         struct netlbl_dom_map *dom_entry;
 
+        if ((secattr->flags & NETLBL_SECATTR_DOMAIN) == 0)
+                return -ENOENT;
+
         rcu_read_lock();
         dom_entry = netlbl_domhsh_getentry(secattr->domain);
         if (dom_entry == NULL)
@@ -200,7 +203,7 @@ void netlbl_cache_invalidate(void)
 int netlbl_cache_add(const struct sk_buff *skb,
                      const struct netlbl_lsm_secattr *secattr)
 {
-        if (secattr->cache == NULL)
+        if ((secattr->flags & NETLBL_SECATTR_CACHE) == 0)
                 return -ENOMSG;
 
         if (CIPSO_V4_OPTEXIST(skb))
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 408820486af..1f5bbb246d2 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2254,8 +2254,6 @@ static void selinux_netlbl_cache_add(struct sk_buff *skb, struct context *ctx)
         cache = kzalloc(sizeof(*cache), GFP_ATOMIC);
         if (cache == NULL)
                 goto netlbl_cache_add_return;
-        secattr.cache->free = selinux_netlbl_cache_free;
-        secattr.cache->data = (void *)cache;
 
         cache->type = NETLBL_CACHE_T_MLS;
         if (ebitmap_cpy(&cache->data.mls_label.level[0].cat,
@@ -2268,6 +2266,10 @@ static void selinux_netlbl_cache_add(struct sk_buff *skb, struct context *ctx)
         cache->data.mls_label.level[0].sens = ctx->range.level[0].sens;
         cache->data.mls_label.level[1].sens = ctx->range.level[0].sens;
 
+        secattr.cache->free = selinux_netlbl_cache_free;
+        secattr.cache->data = (void *)cache;
+        secattr.flags = NETLBL_SECATTR_CACHE;
+
         netlbl_cache_add(skb, &secattr);
 
 netlbl_cache_add_return:
@@ -2313,7 +2315,7 @@ static int selinux_netlbl_secattr_to_sid(struct sk_buff *skb,
 
         POLICY_RDLOCK;
 
-        if (secattr->cache) {
+        if (secattr->flags & NETLBL_SECATTR_CACHE) {
                 cache = NETLBL_CACHE(secattr->cache->data);
                 switch (cache->type) {
                 case NETLBL_CACHE_T_SID:
@@ -2346,7 +2348,7 @@ static int selinux_netlbl_secattr_to_sid(struct sk_buff *skb,
                 default:
                         goto netlbl_secattr_to_sid_return;
                 }
-        } else if (secattr->mls_lvl_vld) {
+        } else if (secattr->flags & NETLBL_SECATTR_MLS_LVL) {
                 ctx = sidtab_search(&sidtab, base_sid);
                 if (ctx == NULL)
                         goto netlbl_secattr_to_sid_return;
@@ -2355,7 +2357,7 @@ static int selinux_netlbl_secattr_to_sid(struct sk_buff *skb,
                 ctx_new.role = ctx->role;
                 ctx_new.type = ctx->type;
                 mls_import_lvl(&ctx_new, secattr->mls_lvl, secattr->mls_lvl);
-                if (secattr->mls_cat) {
+                if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
                         if (mls_import_cat(&ctx_new,
                                            secattr->mls_cat,
                                            secattr->mls_cat_len,
@@ -2414,11 +2416,13 @@ static int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 
         netlbl_secattr_init(&secattr);
         rc = netlbl_skbuff_getattr(skb, &secattr);
-        if (rc == 0)
+        if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
                 rc = selinux_netlbl_secattr_to_sid(skb,
                                                    &secattr,
                                                    base_sid,
                                                    sid);
+        else
+                *sid = SECSID_NULL;
         netlbl_secattr_destroy(&secattr);
 
         return rc;
@@ -2455,7 +2459,6 @@ static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
         secattr.domain = kstrdup(policydb.p_type_val_to_name[ctx->type - 1],
                                  GFP_ATOMIC);
         mls_export_lvl(ctx, &secattr.mls_lvl, NULL);
-        secattr.mls_lvl_vld = 1;
         rc = mls_export_cat(ctx,
                             &secattr.mls_cat,
                             &secattr.mls_cat_len,
@@ -2464,6 +2467,10 @@ static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
         if (rc != 0)
                 goto netlbl_socket_setsid_return;
 
+        secattr.flags |= NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
+        if (secattr.mls_cat)
+                secattr.flags |= NETLBL_SECATTR_MLS_CAT;
+
         rc = netlbl_socket_setattr(sock, &secattr);
         if (rc == 0)
                 sksec->nlbl_state = NLBL_LABELED;
@@ -2564,6 +2571,7 @@ void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
 
         netlbl_secattr_init(&secattr);
         if (netlbl_sock_getattr(sk, &secattr) == 0 &&
+            secattr.flags != NETLBL_SECATTR_NONE &&
             selinux_netlbl_secattr_to_sid(NULL,
                                           &secattr,
                                           SECINITSID_UNLABELED,
@@ -2756,7 +2764,7 @@ int selinux_netlbl_socket_setsockopt(struct socket *sock,
             sksec->nlbl_state == NLBL_LABELED) {
                 netlbl_secattr_init(&secattr);
                 rc = netlbl_socket_getattr(sock, &secattr);
-                if (rc == 0 && (secattr.cache || secattr.mls_lvl_vld))
+                if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
                         rc = -EACCES;
                 netlbl_secattr_destroy(&secattr);
         }