cipso: Add support for native local labeling and fixup mapping names

This patch accomplishes three minor tasks: add a new tag type for local
labeling, rename the CIPSO_V4_MAP_STD define to CIPSO_V4_MAP_TRANS and
replace some of the CIPSO "magic numbers" with constants from the header
file.  The first change allows CIPSO to support full LSM labels/contexts,
not just MLS attributes.  The second change brings the mapping names inline
with what userspace is using, compatibility is preserved since we don't
actually change the value.  The last change is to aid readability and help
prevent mistakes.

Signed-off-by: Paul Moore <paul.moore@hp.com>

2 files changed, 108 insertions, 21 deletions

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 23768b9d6b64..490e035c6d90 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -109,6 +109,19 @@ int cipso_v4_rbm_strictvalid = 1;
  * be omitted. */
 #define CIPSO_V4_TAG_RNG_CAT_MAX      8
 
+/* Base length of the local tag (non-standard tag).
+ *  Tag definition (may change between kernel versions)
+ *
+ * 0          8          16         24         32
+ * +----------+----------+----------+----------+
+ * | 10000000 | 00000110 | 32-bit secid value  |
+ * +----------+----------+----------+----------+
+ * | in (host byte order)|
+ * +----------+----------+
+ *
+ */
+#define CIPSO_V4_TAG_LOC_BLEN         6
+
 /*
  * Helper Functions
  */
@@ -467,6 +480,10 @@ int cipso_v4_doi_add(struct cipso_v4_doi *doi_def)
 			if (doi_def->type != CIPSO_V4_MAP_PASS)
 				return -EINVAL;
 			break;
+		case CIPSO_V4_TAG_LOCAL:
+			if (doi_def->type != CIPSO_V4_MAP_LOCAL)
+				return -EINVAL;
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -502,7 +519,7 @@ void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
 		return;
 
 	switch (doi_def->type) {
-	case CIPSO_V4_MAP_STD:
+	case CIPSO_V4_MAP_TRANS:
 		kfree(doi_def->map.std->lvl.cipso);
 		kfree(doi_def->map.std->lvl.local);
 		kfree(doi_def->map.std->cat.cipso);
@@ -673,7 +690,7 @@ static int cipso_v4_map_lvl_valid(const struct cipso_v4_doi *doi_def, u8 level)
 	switch (doi_def->type) {
 	case CIPSO_V4_MAP_PASS:
 		return 0;
-	case CIPSO_V4_MAP_STD:
+	case CIPSO_V4_MAP_TRANS:
 		if (doi_def->map.std->lvl.cipso[level] < CIPSO_V4_INV_LVL)
 			return 0;
 		break;
@@ -702,7 +719,7 @@ static int cipso_v4_map_lvl_hton(const struct cipso_v4_doi *doi_def,
 	case CIPSO_V4_MAP_PASS:
 		*net_lvl = host_lvl;
 		return 0;
-	case CIPSO_V4_MAP_STD:
+	case CIPSO_V4_MAP_TRANS:
 		if (host_lvl < doi_def->map.std->lvl.local_size &&
 		    doi_def->map.std->lvl.local[host_lvl] < CIPSO_V4_INV_LVL) {
 			*net_lvl = doi_def->map.std->lvl.local[host_lvl];
@@ -736,7 +753,7 @@ static int cipso_v4_map_lvl_ntoh(const struct cipso_v4_doi *doi_def,
 	case CIPSO_V4_MAP_PASS:
 		*host_lvl = net_lvl;
 		return 0;
-	case CIPSO_V4_MAP_STD:
+	case CIPSO_V4_MAP_TRANS:
 		map_tbl = doi_def->map.std;
 		if (net_lvl < map_tbl->lvl.cipso_size &&
 		    map_tbl->lvl.cipso[net_lvl] < CIPSO_V4_INV_LVL) {
@@ -773,7 +790,7 @@ static int cipso_v4_map_cat_rbm_valid(const struct cipso_v4_doi *doi_def,
 	switch (doi_def->type) {
 	case CIPSO_V4_MAP_PASS:
 		return 0;
-	case CIPSO_V4_MAP_STD:
+	case CIPSO_V4_MAP_TRANS:
 		cipso_cat_size = doi_def->map.std->cat.cipso_size;
 		cipso_array = doi_def->map.std->cat.cipso;
 		for (;;) {
@@ -821,7 +838,7 @@ static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
 	u32 host_cat_size = 0;
 	u32 *host_cat_array = NULL;
 
-	if (doi_def->type == CIPSO_V4_MAP_STD) {
+	if (doi_def->type == CIPSO_V4_MAP_TRANS) {
 		host_cat_size = doi_def->map.std->cat.local_size;
 		host_cat_array = doi_def->map.std->cat.local;
 	}
@@ -836,7 +853,7 @@ static int cipso_v4_map_cat_rbm_hton(const struct cipso_v4_doi *doi_def,
 		case CIPSO_V4_MAP_PASS:
 			net_spot = host_spot;
 			break;
-		case CIPSO_V4_MAP_STD:
+		case CIPSO_V4_MAP_TRANS:
 			if (host_spot >= host_cat_size)
 				return -EPERM;
 			net_spot = host_cat_array[host_spot];
@@ -882,7 +899,7 @@ static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
 	u32 net_cat_size = 0;
 	u32 *net_cat_array = NULL;
 
-	if (doi_def->type == CIPSO_V4_MAP_STD) {
+	if (doi_def->type == CIPSO_V4_MAP_TRANS) {
 		net_cat_size = doi_def->map.std->cat.cipso_size;
 		net_cat_array = doi_def->map.std->cat.cipso;
 	}
@@ -902,7 +919,7 @@ static int cipso_v4_map_cat_rbm_ntoh(const struct cipso_v4_doi *doi_def,
 		case CIPSO_V4_MAP_PASS:
 			host_spot = net_spot;
 			break;
-		case CIPSO_V4_MAP_STD:
+		case CIPSO_V4_MAP_TRANS:
 			if (net_spot >= net_cat_size)
 				return -EPERM;
 			host_spot = net_cat_array[net_spot];
@@ -1238,7 +1255,7 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
 	} else
 		tag_len = 4;
 
-	buffer[0] = 0x01;
+	buffer[0] = CIPSO_V4_TAG_RBITMAP;
 	buffer[1] = tag_len;
 	buffer[3] = level;
 
@@ -1334,7 +1351,7 @@ static int cipso_v4_gentag_enum(const struct cipso_v4_doi *doi_def,
 	} else
 		tag_len = 4;
 
-	buffer[0] = 0x02;
+	buffer[0] = CIPSO_V4_TAG_ENUM;
 	buffer[1] = tag_len;
 	buffer[3] = level;
 
@@ -1430,7 +1447,7 @@ static int cipso_v4_gentag_rng(const struct cipso_v4_doi *doi_def,
 	} else
 		tag_len = 4;
 
-	buffer[0] = 0x05;
+	buffer[0] = CIPSO_V4_TAG_RANGE;
 	buffer[1] = tag_len;
 	buffer[3] = level;
 
@@ -1484,6 +1501,54 @@ static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
 }
 
 /**
+ * cipso_v4_gentag_loc - Generate a CIPSO local tag (non-standard)
+ * @doi_def: the DOI definition
+ * @secattr: the security attributes
+ * @buffer: the option buffer
+ * @buffer_len: length of buffer in bytes
+ *
+ * Description:
+ * Generate a CIPSO option using the local tag.  Returns the size of the tag
+ * on success, negative values on failure.
+ *
+ */
+static int cipso_v4_gentag_loc(const struct cipso_v4_doi *doi_def,
+			       const struct netlbl_lsm_secattr *secattr,
+			       unsigned char *buffer,
+			       u32 buffer_len)
+{
+	if (!(secattr->flags & NETLBL_SECATTR_SECID))
+		return -EPERM;
+
+	buffer[0] = CIPSO_V4_TAG_LOCAL;
+	buffer[1] = CIPSO_V4_TAG_LOC_BLEN;
+	*(u32 *)&buffer[2] = secattr->attr.secid;
+
+	return CIPSO_V4_TAG_LOC_BLEN;
+}
+
+/**
+ * cipso_v4_parsetag_loc - Parse a CIPSO local tag
+ * @doi_def: the DOI definition
+ * @tag: the CIPSO tag
+ * @secattr: the security attributes
+ *
+ * Description:
+ * Parse a CIPSO local tag and return the security attributes in @secattr.
+ * Return zero on success, negatives values on failure.
+ *
+ */
+static int cipso_v4_parsetag_loc(const struct cipso_v4_doi *doi_def,
+				 const unsigned char *tag,
+				 struct netlbl_lsm_secattr *secattr)
+{
+	secattr->attr.secid = *(u32 *)&tag[2];
+	secattr->flags |= NETLBL_SECATTR_SECID;
+
+	return 0;
+}
+
+/**
  * cipso_v4_validate - Validate a CIPSO option
  * @option: the start of the option, on error it is set to point to the error
  *
@@ -1502,7 +1567,7 @@ static int cipso_v4_parsetag_rng(const struct cipso_v4_doi *doi_def,
  *   that is unrecognized."
  *
  */
-int cipso_v4_validate(unsigned char **option)
+int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
 {
 	unsigned char *opt = *option;
 	unsigned char *tag;
@@ -1527,7 +1592,7 @@ int cipso_v4_validate(unsigned char **option)
 		goto validate_return_locked;
 	}
 
-	opt_iter = 6;
+	opt_iter = CIPSO_V4_HDR_LEN;
 	tag = opt + opt_iter;
 	while (opt_iter < opt_len) {
 		for (tag_iter = 0; doi_def->tags[tag_iter] != tag[0];)
@@ -1545,7 +1610,7 @@ int cipso_v4_validate(unsigned char **option)
 
 		switch (tag[0]) {
 		case CIPSO_V4_TAG_RBITMAP:
-			if (tag_len < 4) {
+			if (tag_len < CIPSO_V4_TAG_RBM_BLEN) {
 				err_offset = opt_iter + 1;
 				goto validate_return_locked;
 			}
@@ -1563,7 +1628,7 @@ int cipso_v4_validate(unsigned char **option)
 					err_offset = opt_iter + 3;
 					goto validate_return_locked;
 				}
-				if (tag_len > 4 &&
+				if (tag_len > CIPSO_V4_TAG_RBM_BLEN &&
 				    cipso_v4_map_cat_rbm_valid(doi_def,
 							    &tag[4],
 							    tag_len - 4) < 0) {
@@ -1573,7 +1638,7 @@ int cipso_v4_validate(unsigned char **option)
 			}
 			break;
 		case CIPSO_V4_TAG_ENUM:
-			if (tag_len < 4) {
+			if (tag_len < CIPSO_V4_TAG_ENUM_BLEN) {
 				err_offset = opt_iter + 1;
 				goto validate_return_locked;
 			}
@@ -1583,7 +1648,7 @@ int cipso_v4_validate(unsigned char **option)
 				err_offset = opt_iter + 3;
 				goto validate_return_locked;
 			}
-			if (tag_len > 4 &&
+			if (tag_len > CIPSO_V4_TAG_ENUM_BLEN &&
 			    cipso_v4_map_cat_enum_valid(doi_def,
 							&tag[4],
 							tag_len - 4) < 0) {
@@ -1592,7 +1657,7 @@ int cipso_v4_validate(unsigned char **option)
 			}
 			break;
 		case CIPSO_V4_TAG_RANGE:
-			if (tag_len < 4) {
+			if (tag_len < CIPSO_V4_TAG_RNG_BLEN) {
 				err_offset = opt_iter + 1;
 				goto validate_return_locked;
 			}
@@ -1602,7 +1667,7 @@ int cipso_v4_validate(unsigned char **option)
 				err_offset = opt_iter + 3;
 				goto validate_return_locked;
 			}
-			if (tag_len > 4 &&
+			if (tag_len > CIPSO_V4_TAG_RNG_BLEN &&
 			    cipso_v4_map_cat_rng_valid(doi_def,
 						       &tag[4],
 						       tag_len - 4) < 0) {
@@ -1610,6 +1675,19 @@ int cipso_v4_validate(unsigned char **option)
 				goto validate_return_locked;
 			}
 			break;
+		case CIPSO_V4_TAG_LOCAL:
+			/* This is a non-standard tag that we only allow for
+			 * local connections, so if the incoming interface is
+			 * not the loopback device drop the packet. */
+			if (!(skb->dev->flags & IFF_LOOPBACK)) {
+				err_offset = opt_iter;
+				goto validate_return_locked;
+			}
+			if (tag_len != CIPSO_V4_TAG_LOC_BLEN) {
+				err_offset = opt_iter + 1;
+				goto validate_return_locked;
+			}
+			break;
 		default:
 			err_offset = opt_iter;
 			goto validate_return_locked;
@@ -1712,6 +1790,12 @@ static int cipso_v4_genopt(unsigned char *buf, u32 buf_len,
 						   &buf[CIPSO_V4_HDR_LEN],
 						   buf_len - CIPSO_V4_HDR_LEN);
 			break;
+		case CIPSO_V4_TAG_LOCAL:
+			ret_val = cipso_v4_gentag_loc(doi_def,
+						   secattr,
+						   &buf[CIPSO_V4_HDR_LEN],
+						   buf_len - CIPSO_V4_HDR_LEN);
+			break;
 		default:
 			return -EPERM;
 		}
@@ -1921,6 +2005,9 @@ static int cipso_v4_getattr(const unsigned char *cipso,
 	case CIPSO_V4_TAG_RANGE:
 		ret_val = cipso_v4_parsetag_rng(doi_def, &cipso[6], secattr);
 		break;
+	case CIPSO_V4_TAG_LOCAL:
+		ret_val = cipso_v4_parsetag_loc(doi_def, &cipso[6], secattr);
+		break;
 	}
 	if (ret_val == 0)
 		secattr->type = NETLBL_NLTYPE_CIPSOV4;
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index be3f18a7a40e..2c88da6e7862 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -438,7 +438,7 @@ int ip_options_compile(struct net *net,
 				goto error;
 			}
 			opt->cipso = optptr - iph;
-			if (cipso_v4_validate(&optptr)) {
+			if (cipso_v4_validate(skb, &optptr)) {
 				pp_ptr = optptr;
 				goto error;
 			}