Smack: allow for significantly longer Smack labels v4

V4 updated to current linux-security#next
Targeted for git://gitorious.org/smack-next/kernel.git

Modern application runtime environments like to use
naming schemes that are structured and generated without
human intervention. Even though the Smack limit of 23
characters for a label name is perfectly rational for
human use there have been complaints that the limit is
a problem in environments where names are composed from
a set or sources, including vendor, author, distribution
channel and application name. Names like

	softwarehouse-pgwodehouse-coolappstore-mellowmuskrats

are becoming harder to avoid. This patch introduces long
label support in Smack. Labels are now limited to 255
characters instead of the old 23.

The primary reason for limiting the labels to 23 characters
was so they could be directly contained in CIPSO category sets.
This is still done were possible, but for labels that are too
large a mapping is required. This is perfectly safe for communication
that stays "on the box" and doesn't require much coordination
between boxes beyond what would have been required to keep label
names consistent.

The bulk of this patch is in smackfs, adding and updating
administrative interfaces. Because existing APIs can't be
changed new ones that do much the same things as old ones
have been introduced.

The Smack specific CIPSO data representation has been removed
and replaced with the data format used by netlabel. The CIPSO
header is now computed when a label is imported rather than
on use. This results in improved IP performance. The smack
label is now allocated separately from the containing structure,
allowing for larger strings.

Four new /smack interfaces have been introduced as four
of the old interfaces strictly required labels be specified
in fixed length arrays.

The access interface is supplemented with the check interface:
	access  "Subject                 Object                  rwxat"
	access2 "Subject Object rwaxt"

The load interface is supplemented with the rules interface:
	load   "Subject                 Object                  rwxat"
	load2  "Subject Object rwaxt"

The load-self interface is supplemented with the self-rules interface:
	load-self   "Subject                 Object                  rwxat"
	load-self2  "Subject Object rwaxt"

The cipso interface is supplemented with the wire interface:
	cipso  "Subject                  lvl cnt  c1  c2 ..."
	cipso2 "Subject lvl cnt  c1  c2 ..."

The old interfaces are maintained for compatibility.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

1 files changed, 116 insertions, 117 deletions

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index c8115f7308f..9f3705e9271 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -19,37 +19,31 @@
 struct smack_known smack_known_huh = {
 	.smk_known	= "?",
 	.smk_secid	= 2,
-	.smk_cipso	= NULL,
 };
 
 struct smack_known smack_known_hat = {
 	.smk_known	= "^",
 	.smk_secid	= 3,
-	.smk_cipso	= NULL,
 };
 
 struct smack_known smack_known_star = {
 	.smk_known	= "*",
 	.smk_secid	= 4,
-	.smk_cipso	= NULL,
 };
 
 struct smack_known smack_known_floor = {
 	.smk_known	= "_",
 	.smk_secid	= 5,
-	.smk_cipso	= NULL,
 };
 
 struct smack_known smack_known_invalid = {
 	.smk_known	= "",
 	.smk_secid	= 6,
-	.smk_cipso	= NULL,
 };
 
 struct smack_known smack_known_web = {
 	.smk_known	= "@",
 	.smk_secid	= 7,
-	.smk_cipso	= NULL,
 };
 
 LIST_HEAD(smack_known_list);
@@ -331,7 +325,7 @@ void smack_log(char *subject_label, char *object_label, int request,
 }
 #endif
 
-static DEFINE_MUTEX(smack_known_lock);
+DEFINE_MUTEX(smack_known_lock);
 
 /**
  * smk_find_entry - find a label on the list, return the list entry
@@ -345,7 +339,7 @@ struct smack_known *smk_find_entry(const char *string)
 	struct smack_known *skp;
 
 	list_for_each_entry_rcu(skp, &smack_known_list, list) {
-		if (strncmp(skp->smk_known, string, SMK_MAXLEN) == 0)
+		if (strcmp(skp->smk_known, string) == 0)
 			return skp;
 	}
 
@@ -356,27 +350,76 @@ struct smack_known *smk_find_entry(const char *string)
  * smk_parse_smack - parse smack label from a text string
  * @string: a text string that might contain a Smack label
  * @len: the maximum size, or zero if it is NULL terminated.
- * @smack: parsed smack label, or NULL if parse error
+ *
+ * Returns a pointer to the clean label, or NULL
  */
-void smk_parse_smack(const char *string, int len, char *smack)
+char *smk_parse_smack(const char *string, int len)
 {
-	int found;
+	char *smack;
 	int i;
 
-	if (len <= 0 || len > SMK_MAXLEN)
-		len = SMK_MAXLEN;
-
-	for (i = 0, found = 0; i < SMK_LABELLEN; i++) {
-		if (found)
-			smack[i] = '\0';
-		else if (i >= len || string[i] > '~' || string[i] <= ' ' ||
-			 string[i] == '/' || string[i] == '"' ||
-			 string[i] == '\\' || string[i] == '\'') {
-			smack[i] = '\0';
-			found = 1;
-		} else
-			smack[i] = string[i];
+	if (len <= 0)
+		len = strlen(string) + 1;
+
+	/*
+	 * Reserve a leading '-' as an indicator that
+	 * this isn't a label, but an option to interfaces
+	 * including /smack/cipso and /smack/cipso2
+	 */
+	if (string[0] == '-')
+		return NULL;
+
+	for (i = 0; i < len; i++)
+		if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
+		    string[i] == '"' || string[i] == '\\' || string[i] == '\'')
+			break;
+
+	if (i == 0 || i >= SMK_LONGLABEL)
+		return NULL;
+
+	smack = kzalloc(i + 1, GFP_KERNEL);
+	if (smack != NULL) {
+		strncpy(smack, string, i + 1);
+		smack[i] = '\0';
 	}
+	return smack;
+}
+
+/**
+ * smk_netlbl_mls - convert a catset to netlabel mls categories
+ * @catset: the Smack categories
+ * @sap: where to put the netlabel categories
+ *
+ * Allocates and fills attr.mls
+ * Returns 0 on success, error code on failure.
+ */
+int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
+			int len)
+{
+	unsigned char *cp;
+	unsigned char m;
+	int cat;
+	int rc;
+	int byte;
+
+	sap->flags |= NETLBL_SECATTR_MLS_CAT;
+	sap->attr.mls.lvl = level;
+	sap->attr.mls.cat = netlbl_secattr_catmap_alloc(GFP_ATOMIC);
+	sap->attr.mls.cat->startbit = 0;
+
+	for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
+		for (m = 0x80; m != 0; m >>= 1, cat++) {
+			if ((m & *cp) == 0)
+				continue;
+			rc = netlbl_secattr_catmap_setbit(sap->attr.mls.cat,
+							  cat, GFP_ATOMIC);
+			if (rc < 0) {
+				netlbl_secattr_catmap_free(sap->attr.mls.cat);
+				return rc;
+			}
+		}
+
+	return 0;
 }
 
 /**
@@ -390,33 +433,59 @@ void smk_parse_smack(const char *string, int len, char *smack)
 struct smack_known *smk_import_entry(const char *string, int len)
 {
 	struct smack_known *skp;
-	char smack[SMK_LABELLEN];
+	char *smack;
+	int slen;
+	int rc;
 
-	smk_parse_smack(string, len, smack);
-	if (smack[0] == '\0')
+	smack = smk_parse_smack(string, len);
+	if (smack == NULL)
 		return NULL;
 
 	mutex_lock(&smack_known_lock);
 
 	skp = smk_find_entry(smack);
+	if (skp != NULL)
+		goto freeout;
 
-	if (skp == NULL) {
-		skp = kzalloc(sizeof(struct smack_known), GFP_KERNEL);
-		if (skp != NULL) {
-			strncpy(skp->smk_known, smack, SMK_MAXLEN);
-			skp->smk_secid = smack_next_secid++;
-			skp->smk_cipso = NULL;
-			INIT_LIST_HEAD(&skp->smk_rules);
-			spin_lock_init(&skp->smk_cipsolock);
-			mutex_init(&skp->smk_rules_lock);
-			/*
-			 * Make sure that the entry is actually
-			 * filled before putting it on the list.
-			 */
-			list_add_rcu(&skp->list, &smack_known_list);
-		}
-	}
+	skp = kzalloc(sizeof(*skp), GFP_KERNEL);
+	if (skp == NULL)
+		goto freeout;
 
+	skp->smk_known = smack;
+	skp->smk_secid = smack_next_secid++;
+	skp->smk_netlabel.domain = skp->smk_known;
+	skp->smk_netlabel.flags =
+		NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
+	/*
+	 * If direct labeling works use it.
+	 * Otherwise use mapped labeling.
+	 */
+	slen = strlen(smack);
+	if (slen < SMK_CIPSOLEN)
+		rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
+			       &skp->smk_netlabel, slen);
+	else
+		rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
+			       &skp->smk_netlabel, sizeof(skp->smk_secid));
+
+	if (rc >= 0) {
+		INIT_LIST_HEAD(&skp->smk_rules);
+		mutex_init(&skp->smk_rules_lock);
+		/*
+		 * Make sure that the entry is actually
+		 * filled before putting it on the list.
+		 */
+		list_add_rcu(&skp->list, &smack_known_list);
+		goto unlockout;
+	}
+	/*
+	 * smk_netlbl_mls failed.
+	 */
+	kfree(skp);
+	skp = NULL;
+freeout:
+	kfree(smack);
+unlockout:
 	mutex_unlock(&smack_known_lock);
 
 	return skp;
@@ -479,79 +548,9 @@ char *smack_from_secid(const u32 secid)
  */
 u32 smack_to_secid(const char *smack)
 {
-	struct smack_known *skp;
+	struct smack_known *skp = smk_find_entry(smack);
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(skp, &smack_known_list, list) {
-		if (strncmp(skp->smk_known, smack, SMK_MAXLEN) == 0) {
-			rcu_read_unlock();
-			return skp->smk_secid;
-		}
-	}
-	rcu_read_unlock();
-	return 0;
-}
-
-/**
- * smack_from_cipso - find the Smack label associated with a CIPSO option
- * @level: Bell & LaPadula level from the network
- * @cp: Bell & LaPadula categories from the network
- *
- * This is a simple lookup in the label table.
- *
- * Return the matching label from the label list or NULL.
- */
-char *smack_from_cipso(u32 level, char *cp)
-{
-	struct smack_known *kp;
-	char *final = NULL;
-
-	rcu_read_lock();
-	list_for_each_entry(kp, &smack_known_list, list) {
-		if (kp->smk_cipso == NULL)
-			continue;
-
-		spin_lock_bh(&kp->smk_cipsolock);
-
-		if (kp->smk_cipso->smk_level == level &&
-		    memcmp(kp->smk_cipso->smk_catset, cp, SMK_LABELLEN) == 0)
-			final = kp->smk_known;
-
-		spin_unlock_bh(&kp->smk_cipsolock);
-
-		if (final != NULL)
-			break;
-	}
-	rcu_read_unlock();
-
-	return final;
-}
-
-/**
- * smack_to_cipso - find the CIPSO option to go with a Smack label
- * @smack: a pointer to the smack label in question
- * @cp: where to put the result
- *
- * Returns zero if a value is available, non-zero otherwise.
- */
-int smack_to_cipso(const char *smack, struct smack_cipso *cp)
-{
-	struct smack_known *kp;
-	int found = 0;
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(kp, &smack_known_list, list) {
-		if (kp->smk_known == smack ||
-		    strcmp(kp->smk_known, smack) == 0) {
-			found = 1;
-			break;
-		}
-	}
-	rcu_read_unlock();
-
-	if (found == 0 || kp->smk_cipso == NULL)
-		return -ENOENT;
-
-	memcpy(cp, kp->smk_cipso, sizeof(struct smack_cipso));
-	return 0;
+	if (skp == NULL)
+		return 0;
+	return skp->smk_secid;
 }