Smack: Use the netlabel cache

Utilize the Netlabel cache mechanism for incoming packet matching.
Refactor the initialization of secattr structures, as it was being
done in two places.

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

Author: cschaufler

security/smack/smack.h

@@ -297,6 +297,7 @@ struct smack_known *smk_find_entry(const char *);
 bool smack_privileged(int cap);
 bool smack_privileged_cred(int cap, const struct cred *cred);
 void smk_destroy_label_list(struct list_head *list);
+int smack_populate_secattr(struct smack_known *skp);
 
 /*
  * Shared data.

security/smack/smack_access.c

@@ -510,6 +510,42 @@ int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
 	return 0;
 }
 
+/**
+ * smack_populate_secattr - fill in the smack_known netlabel information
+ * @skp: pointer to the structure to fill
+ *
+ * Populate the netlabel secattr structure for a Smack label.
+ *
+ * Returns 0 unless creating the category mapping fails
+ */
+int smack_populate_secattr(struct smack_known *skp)
+{
+	int slen;
+
+	skp->smk_netlabel.attr.secid = skp->smk_secid;
+	skp->smk_netlabel.domain = skp->smk_known;
+	skp->smk_netlabel.cache = netlbl_secattr_cache_alloc(GFP_ATOMIC);
+	if (skp->smk_netlabel.cache != NULL) {
+		skp->smk_netlabel.flags |= NETLBL_SECATTR_CACHE;
+		skp->smk_netlabel.cache->free = NULL;
+		skp->smk_netlabel.cache->data = skp;
+	}
+	skp->smk_netlabel.flags |= NETLBL_SECATTR_SECID |
+				   NETLBL_SECATTR_MLS_LVL |
+				   NETLBL_SECATTR_DOMAIN;
+	/*
+	 * If direct labeling works use it.
+	 * Otherwise use mapped labeling.
+	 */
+	slen = strlen(skp->smk_known);
+	if (slen < SMK_CIPSOLEN)
+		return smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
+				      &skp->smk_netlabel, slen);
+
+	return smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
+			      &skp->smk_netlabel, sizeof(skp->smk_secid));
+}
+
 /**
  * smk_import_entry - import a label, return the list entry
  * @string: a text string that might be a Smack label
@@ -523,7 +559,6 @@ struct smack_known *smk_import_entry(const char *string, int len)
 {
 	struct smack_known *skp;
 	char *smack;
-	int slen;
 	int rc;
 
 	smack = smk_parse_smack(string, len);
@@ -544,21 +579,8 @@ struct smack_known *smk_import_entry(const char *string, int len)
 
 	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));
 
+	rc = smack_populate_secattr(skp);
 	if (rc >= 0) {
 		INIT_LIST_HEAD(&skp->smk_rules);
 		mutex_init(&skp->smk_rules_lock);
@@ -569,9 +591,6 @@ struct smack_known *smk_import_entry(const char *string, int len)
 		smk_insert_entry(skp);
 		goto unlockout;
 	}
-	/*
-	 * smk_netlbl_mls failed.
-	 */
 	kfree(skp);
 	skp = ERR_PTR(rc);
 freeout:

security/smack/smack_lsm.c

@@ -3715,6 +3715,18 @@ static struct smack_known *smack_from_secattr(struct netlbl_lsm_secattr *sap,
 	int acat;
 	int kcat;
 
+	/*
+	 * Netlabel found it in the cache.
+	 */
+	if ((sap->flags & NETLBL_SECATTR_CACHE) != 0)
+		return (struct smack_known *)sap->cache->data;
+
+	if ((sap->flags & NETLBL_SECATTR_SECID) != 0)
+		/*
+		 * Looks like a fallback, which gives us a secid.
+		 */
+		return smack_from_secid(sap->attr.secid);
+
 	if ((sap->flags & NETLBL_SECATTR_MLS_LVL) != 0) {
 		/*
 		 * Looks like a CIPSO packet.
@@ -3762,11 +3774,6 @@ static struct smack_known *smack_from_secattr(struct netlbl_lsm_secattr *sap,
 			return &smack_known_web;
 		return &smack_known_star;
 	}
-	if ((sap->flags & NETLBL_SECATTR_SECID) != 0)
-		/*
-		 * Looks like a fallback, which gives us a secid.
-		 */
-		return smack_from_secid(sap->attr.secid);
 	/*
 	 * Without guidance regarding the smack value
 	 * for the packet fall back on the network
@@ -3845,6 +3852,9 @@ static struct smack_known *smack_from_skb(struct sk_buff *skb)
  * @family: address family
  * @skb: packet
  *
+ * Find the Smack label in the IP options. If it hasn't been
+ * added to the netlabel cache, add it here.
+ *
  * Returns smack_known of the IP options or NULL if that won't work.
  */
 static struct smack_known *smack_from_netlbl(struct sock *sk, u16 family,
@@ -3853,13 +3863,18 @@ static struct smack_known *smack_from_netlbl(struct sock *sk, u16 family,
 	struct netlbl_lsm_secattr secattr;
 	struct socket_smack *ssp = NULL;
 	struct smack_known *skp = NULL;
+	int rc = 0;
 
 	netlbl_secattr_init(&secattr);
 
 	if (sk)
 		ssp = sk->sk_security;
-	if (netlbl_skbuff_getattr(skb, family, &secattr) == 0)
+
+	if (netlbl_skbuff_getattr(skb, family, &secattr) == 0) {
 		skp = smack_from_secattr(&secattr, ssp);
+		if (secattr.flags & NETLBL_SECATTR_CACHEABLE)
+			rc = netlbl_cache_add(skb, family, &skp->smk_netlabel);
+	}
 
 	netlbl_secattr_destroy(&secattr);
 

security/smack/smackfs.c

@@ -922,6 +922,10 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
 		skp->smk_netlabel.attr.mls.cat = ncats.attr.mls.cat;
 		skp->smk_netlabel.attr.mls.lvl = ncats.attr.mls.lvl;
 		rc = count;
+		/*
+		 * This mapping may have been cached, so clear the cache.
+		 */
+		netlbl_cache_invalidate();
 	}
 
 out:
@@ -2950,15 +2954,6 @@ static struct file_system_type smk_fs_type = {
 
 static struct vfsmount *smackfs_mount;
 
-static int __init smk_preset_netlabel(struct smack_known *skp)
-{
-	skp->smk_netlabel.domain = skp->smk_known;
-	skp->smk_netlabel.flags =
-		NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
-	return smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
-				&skp->smk_netlabel, strlen(skp->smk_known));
-}
-
 /**
  * init_smk_fs - get the smackfs superblock
  *
@@ -2997,19 +2992,19 @@ static int __init init_smk_fs(void)
 	smk_cipso_doi();
 	smk_unlbl_ambient(NULL);
 
-	rc = smk_preset_netlabel(&smack_known_floor);
+	rc = smack_populate_secattr(&smack_known_floor);
 	if (err == 0 && rc < 0)
 		err = rc;
-	rc = smk_preset_netlabel(&smack_known_hat);
+	rc = smack_populate_secattr(&smack_known_hat);
 	if (err == 0 && rc < 0)
 		err = rc;
-	rc = smk_preset_netlabel(&smack_known_huh);
+	rc = smack_populate_secattr(&smack_known_huh);
 	if (err == 0 && rc < 0)
 		err = rc;
-	rc = smk_preset_netlabel(&smack_known_star);
+	rc = smack_populate_secattr(&smack_known_star);
 	if (err == 0 && rc < 0)
 		err = rc;
-	rc = smk_preset_netlabel(&smack_known_web);
+	rc = smack_populate_secattr(&smack_known_web);
 	if (err == 0 && rc < 0)
 		err = rc;