NetLabel: Add secid token support to the NetLabel secattr struct

This patch adds support to the NetLabel LSM secattr struct for a secid token
and a type field, paving the way for full LSM/SELinux context support and
"static" or "fallback" labels.  In addition, this patch adds a fair amount
of documentation to the core NetLabel structures used as part of the
NetLabel kernel API.

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

5 files changed, 120 insertions, 46 deletions

diff --git a/include/net/netlabel.h b/include/net/netlabel.h
index 2e5b2f6f9fa0..18b73cf507df 100644
--- a/include/net/netlabel.h
+++ b/include/net/netlabel.h
@@ -105,17 +105,49 @@ struct netlbl_dom_map;
 /* Domain mapping operations */
 int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info);
 
-/* LSM security attributes */
+/*
+ * LSM security attributes
+ */
+
+/**
+ * struct netlbl_lsm_cache - NetLabel LSM security attribute cache
+ * @refcount: atomic reference counter
+ * @free: LSM supplied function to free the cache data
+ * @data: LSM supplied cache data
+ *
+ * Description:
+ * This structure is provided for LSMs which wish to make use of the NetLabel
+ * caching mechanism to store LSM specific data/attributes in the NetLabel
+ * cache.  If the LSM has to perform a lot of translation from the NetLabel
+ * security attributes into it's own internal representation then the cache
+ * mechanism can provide a way to eliminate some or all of that translation
+ * overhead on a cache hit.
+ *
+ */
 struct netlbl_lsm_cache {
         atomic_t refcount;
         void (*free) (const void *data);
         void *data;
 };
-/* The catmap bitmap field MUST be a power of two in length and large
+
+/**
+ * struct netlbl_lsm_secattr_catmap - NetLabel LSM secattr category bitmap
+ * @startbit: the value of the lowest order bit in the bitmap
+ * @bitmap: the category bitmap
+ * @next: pointer to the next bitmap "node" or NULL
+ *
+ * Description:
+ * This structure is used to represent category bitmaps.  Due to the large
+ * number of categories supported by most labeling protocols it is not
+ * practical to transfer a full bitmap internally so NetLabel adopts a sparse
+ * bitmap structure modeled after SELinux's ebitmap structure.
+ * The catmap bitmap field MUST be a power of two in length and large
  * enough to hold at least 240 bits.  Special care (i.e. check the code!)
  * should be used when changing these values as the LSM implementation
  * probably has functions which rely on the sizes of these types to speed
- * processing. */
+ * processing.
+ *
+ */
 #define NETLBL_CATMAP_MAPTYPE           u64
 #define NETLBL_CATMAP_MAPCNT            4
 #define NETLBL_CATMAP_MAPSIZE           (sizeof(NETLBL_CATMAP_MAPTYPE) * 8)
@@ -127,22 +159,48 @@ struct netlbl_lsm_secattr_catmap {
         NETLBL_CATMAP_MAPTYPE bitmap[NETLBL_CATMAP_MAPCNT];
         struct netlbl_lsm_secattr_catmap *next;
 };
+
+/**
+ * struct netlbl_lsm_secattr - NetLabel LSM security attributes
+ * @flags: indicate which attributes are contained in this structure
+ * @type: indicate the NLTYPE of the attributes
+ * @domain: the NetLabel LSM domain
+ * @cache: NetLabel LSM specific cache
+ * @attr.mls: MLS sensitivity label
+ * @attr.mls.cat: MLS category bitmap
+ * @attr.mls.lvl: MLS sensitivity level
+ * @attr.secid: LSM specific secid token
+ *
+ * Description:
+ * This structure is used to pass security attributes between NetLabel and the
+ * LSM modules.  The flags field is used to specify which fields within the
+ * struct are valid and valid values can be created by bitwise OR'ing the
+ * NETLBL_SECATTR_* defines.  The domain field is typically set by the LSM to
+ * specify domain specific configuration settings and is not usually used by
+ * NetLabel itself when returning security attributes to the LSM.
+ *
+ */
 #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
+#define NETLBL_SECATTR_SECID            0x00000010
 #define NETLBL_SECATTR_CACHEABLE        (NETLBL_SECATTR_MLS_LVL | \
-                                         NETLBL_SECATTR_MLS_CAT)
+                                         NETLBL_SECATTR_MLS_CAT | \
+                                         NETLBL_SECATTR_SECID)
 struct netlbl_lsm_secattr {
         u32 flags;
-
+        u32 type;
         char *domain;
-
-        u32 mls_lvl;
-        struct netlbl_lsm_secattr_catmap *mls_cat;
-
         struct netlbl_lsm_cache *cache;
+        union {
+                struct {
+                        struct netlbl_lsm_secattr_catmap *cat;
+                        u32 lvl;
+                } mls;
+                u32 secid;
+        } attr;
 };
 
 /*
@@ -231,10 +289,7 @@ static inline void netlbl_secattr_catmap_free(
  */
 static inline void netlbl_secattr_init(struct netlbl_lsm_secattr *secattr)
 {
-        secattr->flags = 0;
-        secattr->domain = NULL;
-        secattr->mls_cat = NULL;
-        secattr->cache = NULL;
+        memset(secattr, 0, sizeof(*secattr));
 }
 
 /**
@@ -248,11 +303,11 @@ static inline void netlbl_secattr_init(struct netlbl_lsm_secattr *secattr)
  */
 static inline void netlbl_secattr_destroy(struct netlbl_lsm_secattr *secattr)
 {
-        if (secattr->cache)
-                netlbl_secattr_cache_free(secattr->cache);
         kfree(secattr->domain);
-        if (secattr->mls_cat)
-                netlbl_secattr_catmap_free(secattr->mls_cat);
+        if (secattr->flags & NETLBL_SECATTR_CACHE)
+                netlbl_secattr_cache_free(secattr->cache);
+        if (secattr->flags & NETLBL_SECATTR_MLS_CAT)
+                netlbl_secattr_catmap_free(secattr->attr.mls.cat);
 }
 
 /**
@@ -300,7 +355,7 @@ int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
                                  gfp_t flags);
 
 /*
- * LSM protocol operations
+ * LSM protocol operations (NetLabel LSM/kernel API)
  */
 int netlbl_enabled(void);
 int netlbl_sock_setattr(struct sock *sk,
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index d4dc4eb48d95..a2241060113b 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -348,6 +348,7 @@ static int cipso_v4_cache_check(const unsigned char *key,
                         atomic_inc(&entry->lsm_data->refcount);
                         secattr->cache = entry->lsm_data;
                         secattr->flags |= NETLBL_SECATTR_CACHE;
+                        secattr->type = NETLBL_NLTYPE_CIPSOV4;
                         if (prev_entry == NULL) {
                                 spin_unlock_bh(&cipso_v4_cache[bkt].lock);
                                 return 0;
@@ -865,7 +866,7 @@ static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
         }
 
         for (;;) {
-                host_spot = netlbl_secattr_catmap_walk(secattr->mls_cat,
+                host_spot = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
                                                        host_spot + 1);
                 if (host_spot < 0)
                         break;
@@ -948,7 +949,7 @@ static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
                                 return -EPERM;
                         break;
                 }
-                ret_val = netlbl_secattr_catmap_setbit(secattr->mls_cat,
+                ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,
                                                        host_spot,
                                                        GFP_ATOMIC);
                 if (ret_val != 0)
@@ -1014,7 +1015,8 @@ static int cipso_v4_map_cat_enum_hton(const struct cipso_v4_doi *doi_def,
         u32 cat_iter = 0;
 
         for (;;) {
-                cat = netlbl_secattr_catmap_walk(secattr->mls_cat, cat + 1);
+                cat = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
+                                                 cat + 1);
                 if (cat < 0)
                         break;
                 if ((cat_iter + 2) > net_cat_len)
@@ -1049,7 +1051,7 @@ static int cipso_v4_map_cat_enum_ntoh(const struct cipso_v4_doi *doi_def,
         u32 iter;
 
         for (iter = 0; iter < net_cat_len; iter += 2) {
-                ret_val = netlbl_secattr_catmap_setbit(secattr->mls_cat,
+                ret_val = netlbl_secattr_catmap_setbit(secattr->attr.mls.cat,
                                 ntohs(get_unaligned((__be16 *)&net_cat[iter])),
                                 GFP_ATOMIC);
                 if (ret_val != 0)
@@ -1130,7 +1132,8 @@ static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def,
                 return -ENOSPC;
 
         for (;;) {
-                iter = netlbl_secattr_catmap_walk(secattr->mls_cat, iter + 1);
+                iter = netlbl_secattr_catmap_walk(secattr->attr.mls.cat,
+                                                  iter + 1);
                 if (iter < 0)
                         break;
                 cat_size += (iter == 0 ? 0 : sizeof(u16));
@@ -1138,7 +1141,8 @@ static int cipso_v4_map_cat_rng_hton(const struct cipso_v4_doi *doi_def,
                         return -ENOSPC;
                 array[array_cnt++] = iter;
 
-                iter = netlbl_secattr_catmap_walk_rng(secattr->mls_cat, iter);
+                iter = netlbl_secattr_catmap_walk_rng(secattr->attr.mls.cat,
+                                                      iter);
                 if (iter < 0)
                         return -EFAULT;
                 cat_size += sizeof(u16);
@@ -1191,7 +1195,7 @@ static int cipso_v4_map_cat_rng_ntoh(const struct cipso_v4_doi *doi_def,
                 else
                         cat_low = 0;
 
-                ret_val = netlbl_secattr_catmap_setrng(secattr->mls_cat,
+                ret_val = netlbl_secattr_catmap_setrng(secattr->attr.mls.cat,
                                                        cat_low,
                                                        cat_high,
                                                        GFP_ATOMIC);
@@ -1251,7 +1255,9 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
         if ((secattr->flags & NETLBL_SECATTR_MLS_LVL) == 0)
                 return -EPERM;
 
-        ret_val = cipso_v4_map_lvl_hton(doi_def, secattr->mls_lvl, &level);
+        ret_val = cipso_v4_map_lvl_hton(doi_def,
+                                        secattr->attr.mls.lvl,
+                                        &level);
         if (ret_val != 0)
                 return ret_val;
 
@@ -1303,12 +1309,13 @@ static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
         ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
         if (ret_val != 0)
                 return ret_val;
-        secattr->mls_lvl = level;
+        secattr->attr.mls.lvl = level;
         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
         if (tag_len > 4) {
-                secattr->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
-                if (secattr->mls_cat == NULL)
+                secattr->attr.mls.cat =
+                                       netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+                if (secattr->attr.mls.cat == NULL)
                         return -ENOMEM;
 
                 ret_val = cipso_v4_map_cat_rbm_ntoh(doi_def,
@@ -1316,7 +1323,7 @@ static int cipso_v4_parsetag_rbm(const struct cipso_v4_doi *doi_def,
                                                     tag_len - 4,
                                                     secattr);
                 if (ret_val != 0) {
-                        netlbl_secattr_catmap_free(secattr->mls_cat);
+                        netlbl_secattr_catmap_free(secattr->attr.mls.cat);
                         return ret_val;
                 }
 
@@ -1350,7 +1357,9 @@ static int cipso_v4_gentag_enum(const struct cipso_v4_doi *doi_def,
         if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
                 return -EPERM;
 
-        ret_val = cipso_v4_map_lvl_hton(doi_def, secattr->mls_lvl, &level);
+        ret_val = cipso_v4_map_lvl_hton(doi_def,
+                                        secattr->attr.mls.lvl,
+                                        &level);
         if (ret_val != 0)
                 return ret_val;
 
@@ -1396,12 +1405,13 @@ static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
         ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
         if (ret_val != 0)
                 return ret_val;
-        secattr->mls_lvl = level;
+        secattr->attr.mls.lvl = level;
         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
         if (tag_len > 4) {
-                secattr->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
-                if (secattr->mls_cat == NULL)
+                secattr->attr.mls.cat =
+                                       netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+                if (secattr->attr.mls.cat == NULL)
                         return -ENOMEM;
 
                 ret_val = cipso_v4_map_cat_enum_ntoh(doi_def,
@@ -1409,7 +1419,7 @@ static int cipso_v4_parsetag_enum(const struct cipso_v4_doi *doi_def,
                                                      tag_len - 4,
                                                      secattr);
                 if (ret_val != 0) {
-                        netlbl_secattr_catmap_free(secattr->mls_cat);
+                        netlbl_secattr_catmap_free(secattr->attr.mls.cat);
                         return ret_val;
                 }
 
@@ -1443,7 +1453,9 @@ static int cipso_v4_gentag_rng(const struct cipso_v4_doi *doi_def,
         if (!(secattr->flags & NETLBL_SECATTR_MLS_LVL))
                 return -EPERM;
 
-        ret_val = cipso_v4_map_lvl_hton(doi_def, secattr->mls_lvl, &level);
+        ret_val = cipso_v4_map_lvl_hton(doi_def,
+                                        secattr->attr.mls.lvl,
+                                        &level);
         if (ret_val != 0)
                 return ret_val;
 
@@ -1488,12 +1500,13 @@ static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
         ret_val = cipso_v4_map_lvl_ntoh(doi_def, tag[3], &level);
         if (ret_val != 0)
                 return ret_val;
-        secattr->mls_lvl = level;
+        secattr->attr.mls.lvl = level;
         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 
         if (tag_len > 4) {
-                secattr->mls_cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
-                if (secattr->mls_cat == NULL)
+                secattr->attr.mls.cat =
+                                       netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+                if (secattr->attr.mls.cat == NULL)
                         return -ENOMEM;
 
                 ret_val = cipso_v4_map_cat_rng_ntoh(doi_def,
@@ -1501,7 +1514,7 @@ static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
                                                     tag_len - 4,
                                                     secattr);
                 if (ret_val != 0) {
-                        netlbl_secattr_catmap_free(secattr->mls_cat);
+                        netlbl_secattr_catmap_free(secattr->attr.mls.cat);
                         return ret_val;
                 }
 
@@ -1850,6 +1863,8 @@ static int cipso_v4_getattr(const unsigned char *cipso,
                 ret_val = cipso_v4_parsetag_rng(doi_def, &cipso[6], secattr);
                 break;
         }
+        if (ret_val == 0)
+                secattr->type = NETLBL_NLTYPE_CIPSOV4;
 
 getattr_return:
         rcu_read_unlock();
diff --git a/net/netlabel/netlabel_unlabeled.c b/net/netlabel/netlabel_unlabeled.c
index fd53c7ae2977..7f5df0cbc63f 100644
--- a/net/netlabel/netlabel_unlabeled.c
+++ b/net/netlabel/netlabel_unlabeled.c
@@ -241,6 +241,7 @@ int netlbl_unlabel_getattr(struct netlbl_lsm_secattr *secattr)
         if (netlabel_unlabel_acceptflg == 0)
                 return -ENOMSG;
         netlbl_secattr_init(secattr);
+        secattr->type = NETLBL_NLTYPE_UNLABELED;
         return 0;
 }
 
diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c
index 3bbcb5369af9..feaf0a5b828f 100644
--- a/security/selinux/ss/mls.c
+++ b/security/selinux/ss/mls.c
@@ -562,7 +562,7 @@ void mls_export_netlbl_lvl(struct context *context,
         if (!selinux_mls_enabled)
                 return;
 
-        secattr->mls_lvl = context->range.level[0].sens - 1;
+        secattr->attr.mls.lvl = context->range.level[0].sens - 1;
         secattr->flags |= NETLBL_SECATTR_MLS_LVL;
 }
 
@@ -582,7 +582,7 @@ void mls_import_netlbl_lvl(struct context *context,
         if (!selinux_mls_enabled)
                 return;
 
-        context->range.level[0].sens = secattr->mls_lvl + 1;
+        context->range.level[0].sens = secattr->attr.mls.lvl + 1;
         context->range.level[1].sens = context->range.level[0].sens;
 }
 
@@ -605,8 +605,8 @@ int mls_export_netlbl_cat(struct context *context,
                 return 0;
 
         rc = ebitmap_netlbl_export(&context->range.level[0].cat,
-                                   &secattr->mls_cat);
-        if (rc == 0 && secattr->mls_cat != NULL)
+                                   &secattr->attr.mls.cat);
+        if (rc == 0 && secattr->attr.mls.cat != NULL)
                 secattr->flags |= NETLBL_SECATTR_MLS_CAT;
 
         return rc;
@@ -633,7 +633,7 @@ int mls_import_netlbl_cat(struct context *context,
                 return 0;
 
         rc = ebitmap_netlbl_import(&context->range.level[0].cat,
-                                   secattr->mls_cat);
+                                   secattr->attr.mls.cat);
         if (rc != 0)
                 goto import_netlbl_cat_failure;
 
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 4bf715d4cf29..0f97ef578370 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2550,6 +2550,9 @@ int security_netlbl_secattr_to_sid(struct netlbl_lsm_secattr *secattr,
                 default:
                         goto netlbl_secattr_to_sid_return;
                 }
+        } else if (secattr->flags & NETLBL_SECATTR_SECID) {
+                *sid = secattr->attr.secid;
+                rc = 0;
         } else if (secattr->flags & NETLBL_SECATTR_MLS_LVL) {
                 ctx = sidtab_search(&sidtab, base_sid);
                 if (ctx == NULL)
@@ -2561,7 +2564,7 @@ int security_netlbl_secattr_to_sid(struct netlbl_lsm_secattr *secattr,
                 mls_import_netlbl_lvl(&ctx_new, secattr);
                 if (secattr->flags & NETLBL_SECATTR_MLS_CAT) {
                         if (ebitmap_netlbl_import(&ctx_new.range.level[0].cat,
-                                                  secattr->mls_cat) != 0)
+                                                  secattr->attr.mls.cat) != 0)
                                 goto netlbl_secattr_to_sid_return;
                         ctx_new.range.level[1].cat.highbit =
                                 ctx_new.range.level[0].cat.highbit;