1 files changed, 168 insertions, 72 deletions

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index e493063a3c34..07f033634b27 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -74,7 +74,7 @@ struct ima_rule_entry {
 	int pcr;
 	struct {
 		void *rule;	/* LSM file metadata specific */
-		void *args_p;	/* audit value */
+		char *args_p;	/* audit value */
 		int type;	/* audit type */
 	} lsm[MAX_LSM_RULES];
 	char *fsname;
@@ -258,9 +258,24 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry)
 	int i;
 
 	for (i = 0; i < MAX_LSM_RULES; i++) {
-		kfree(entry->lsm[i].rule);
+		ima_filter_rule_free(entry->lsm[i].rule);
 		kfree(entry->lsm[i].args_p);
 	}
+}
+
+static void ima_free_rule(struct ima_rule_entry *entry)
+{
+	if (!entry)
+		return;
+
+	/*
+	 * entry->template->fields may be allocated in ima_parse_rule() but that
+	 * reference is owned by the corresponding ima_template_desc element in
+	 * the defined_templates list and cannot be freed here
+	 */
+	kfree(entry->fsname);
+	kfree(entry->keyrings);
+	ima_lsm_free_rule(entry);
 	kfree(entry);
 }
 
@@ -285,24 +300,22 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 			continue;
 
 		nentry->lsm[i].type = entry->lsm[i].type;
-		nentry->lsm[i].args_p = kstrdup(entry->lsm[i].args_p,
-						GFP_KERNEL);
-		if (!nentry->lsm[i].args_p)
-			goto out_err;
-
-		security_filter_rule_init(nentry->lsm[i].type,
-					  Audit_equal,
-					  nentry->lsm[i].args_p,
-					  &nentry->lsm[i].rule);
+		nentry->lsm[i].args_p = entry->lsm[i].args_p;
+		/*
+		 * Remove the reference from entry so that the associated
+		 * memory will not be freed during a later call to
+		 * ima_lsm_free_rule(entry).
+		 */
+		entry->lsm[i].args_p = NULL;
+
+		ima_filter_rule_init(nentry->lsm[i].type, Audit_equal,
+				     nentry->lsm[i].args_p,
+				     &nentry->lsm[i].rule);
 		if (!nentry->lsm[i].rule)
 			pr_warn("rule for LSM \'%s\' is undefined\n",
-				(char *)entry->lsm[i].args_p);
+				nentry->lsm[i].args_p);
 	}
 	return nentry;
-
-out_err:
-	ima_lsm_free_rule(nentry);
-	return NULL;
 }
 
 static int ima_lsm_update_rule(struct ima_rule_entry *entry)
@@ -315,11 +328,29 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
 
 	list_replace_rcu(&entry->list, &nentry->list);
 	synchronize_rcu();
+	/*
+	 * ima_lsm_copy_rule() shallow copied all references, except for the
+	 * LSM references, from entry to nentry so we only want to free the LSM
+	 * references and the entry itself. All other memory refrences will now
+	 * be owned by nentry.
+	 */
 	ima_lsm_free_rule(entry);
+	kfree(entry);
 
 	return 0;
 }
 
+static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
+{
+	int i;
+
+	for (i = 0; i < MAX_LSM_RULES; i++)
+		if (entry->lsm[i].args_p)
+			return true;
+
+	return false;
+}
+
 /*
  * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
  * to the old, stale LSM policy.  Update the IMA LSM based rules to reflect
@@ -328,17 +359,10 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
 static void ima_lsm_update_rules(void)
 {
 	struct ima_rule_entry *entry, *e;
-	int i, result, needs_update;
+	int result;
 
 	list_for_each_entry_safe(entry, e, &ima_policy_rules, list) {
-		needs_update = 0;
-		for (i = 0; i < MAX_LSM_RULES; i++) {
-			if (entry->lsm[i].args_p) {
-				needs_update = 1;
-				break;
-			}
-		}
-		if (!needs_update)
+		if (!ima_rule_contains_lsm_cond(entry))
 			continue;
 
 		result = ima_lsm_update_rule(entry);
@@ -418,13 +442,9 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 {
 	int i;
 
-	if ((func == KEXEC_CMDLINE) || (func == KEY_CHECK)) {
-		if ((rule->flags & IMA_FUNC) && (rule->func == func)) {
-			if (func == KEY_CHECK)
-				return ima_match_keyring(rule, keyring, cred);
-			return true;
-		}
-		return false;
+	if (func == KEY_CHECK) {
+		return (rule->flags & IMA_FUNC) && (rule->func == func) &&
+		       ima_match_keyring(rule, keyring, cred);
 	}
 	if ((rule->flags & IMA_FUNC) &&
 	    (rule->func != func && func != POST_SETATTR))
@@ -474,18 +494,16 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
 		case LSM_OBJ_ROLE:
 		case LSM_OBJ_TYPE:
 			security_inode_getsecid(inode, &osid);
-			rc = security_filter_rule_match(osid,
-							rule->lsm[i].type,
-							Audit_equal,
-							rule->lsm[i].rule);
+			rc = ima_filter_rule_match(osid, rule->lsm[i].type,
+						   Audit_equal,
+						   rule->lsm[i].rule);
 			break;
 		case LSM_SUBJ_USER:
 		case LSM_SUBJ_ROLE:
 		case LSM_SUBJ_TYPE:
-			rc = security_filter_rule_match(secid,
-							rule->lsm[i].type,
-							Audit_equal,
-							rule->lsm[i].rule);
+			rc = ima_filter_rule_match(secid, rule->lsm[i].type,
+						   Audit_equal,
+						   rule->lsm[i].rule);
 		default:
 			break;
 		}
@@ -880,16 +898,16 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 		return -ENOMEM;
 
 	entry->lsm[lsm_rule].type = audit_type;
-	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
-					   Audit_equal,
-					   entry->lsm[lsm_rule].args_p,
-					   &entry->lsm[lsm_rule].rule);
+	result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal,
+				      entry->lsm[lsm_rule].args_p,
+				      &entry->lsm[lsm_rule].rule);
 	if (!entry->lsm[lsm_rule].rule) {
 		pr_warn("rule for LSM \'%s\' is undefined\n",
-			(char *)entry->lsm[lsm_rule].args_p);
+			entry->lsm[lsm_rule].args_p);
 
 		if (ima_rules == &ima_default_rules) {
 			kfree(entry->lsm[lsm_rule].args_p);
+			entry->lsm[lsm_rule].args_p = NULL;
 			result = -EINVAL;
 		} else
 			result = 0;
@@ -949,6 +967,96 @@ static void check_template_modsig(const struct ima_template_desc *template)
 #undef MSG
 }
 
+static bool ima_validate_rule(struct ima_rule_entry *entry)
+{
+	/* Ensure that the action is set and is compatible with the flags */
+	if (entry->action == UNKNOWN)
+		return false;
+
+	if (entry->action != MEASURE && entry->flags & IMA_PCR)
+		return false;
+
+	if (entry->action != APPRAISE &&
+	    entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST))
+		return false;
+
+	/*
+	 * The IMA_FUNC bit must be set if and only if there's a valid hook
+	 * function specified, and vice versa. Enforcing this property allows
+	 * for the NONE case below to validate a rule without an explicit hook
+	 * function.
+	 */
+	if (((entry->flags & IMA_FUNC) && entry->func == NONE) ||
+	    (!(entry->flags & IMA_FUNC) && entry->func != NONE))
+		return false;
+
+	/*
+	 * Ensure that the hook function is compatible with the other
+	 * components of the rule
+	 */
+	switch (entry->func) {
+	case NONE:
+	case FILE_CHECK:
+	case MMAP_CHECK:
+	case BPRM_CHECK:
+	case CREDS_CHECK:
+	case POST_SETATTR:
+	case FIRMWARE_CHECK:
+	case POLICY_CHECK:
+		if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
+				     IMA_UID | IMA_FOWNER | IMA_FSUUID |
+				     IMA_INMASK | IMA_EUID | IMA_PCR |
+				     IMA_FSNAME | IMA_DIGSIG_REQUIRED |
+				     IMA_PERMIT_DIRECTIO))
+			return false;
+
+		break;
+	case MODULE_CHECK:
+	case KEXEC_KERNEL_CHECK:
+	case KEXEC_INITRAMFS_CHECK:
+		if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
+				     IMA_UID | IMA_FOWNER | IMA_FSUUID |
+				     IMA_INMASK | IMA_EUID | IMA_PCR |
+				     IMA_FSNAME | IMA_DIGSIG_REQUIRED |
+				     IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED |
+				     IMA_CHECK_BLACKLIST))
+			return false;
+
+		break;
+	case KEXEC_CMDLINE:
+		if (entry->action & ~(MEASURE | DONT_MEASURE))
+			return false;
+
+		if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID |
+				     IMA_FOWNER | IMA_FSUUID | IMA_EUID |
+				     IMA_PCR | IMA_FSNAME))
+			return false;
+
+		break;
+	case KEY_CHECK:
+		if (entry->action & ~(MEASURE | DONT_MEASURE))
+			return false;
+
+		if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR |
+				     IMA_KEYRINGS))
+			return false;
+
+		if (ima_rule_contains_lsm_cond(entry))
+			return false;
+
+		break;
+	default:
+		return false;
+	}
+
+	/* Ensure that combinations of flags are compatible with each other */
+	if (entry->flags & IMA_CHECK_BLACKLIST &&
+	    !(entry->flags & IMA_MODSIG_ALLOWED))
+		return false;
+
+	return true;
+}
+
 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 {
 	struct audit_buffer *ab;
@@ -1126,8 +1234,6 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			keyrings_len = strlen(args[0].from) + 1;
 
 			if ((entry->keyrings) ||
-			    (entry->action != MEASURE) ||
-			    (entry->func != KEY_CHECK) ||
 			    (keyrings_len < 2)) {
 				result = -EINVAL;
 				break;
@@ -1267,15 +1373,10 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 						   AUDIT_SUBJ_TYPE);
 			break;
 		case Opt_appraise_type:
-			if (entry->action != APPRAISE) {
-				result = -EINVAL;
-				break;
-			}
-
 			ima_log_string(ab, "appraise_type", args[0].from);
 			if ((strcmp(args[0].from, "imasig")) == 0)
 				entry->flags |= IMA_DIGSIG_REQUIRED;
-			else if (ima_hook_supports_modsig(entry->func) &&
+			else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
 				 strcmp(args[0].from, "imasig|modsig") == 0)
 				entry->flags |= IMA_DIGSIG_REQUIRED |
 						IMA_MODSIG_ALLOWED;
@@ -1284,17 +1385,16 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			break;
 		case Opt_appraise_flag:
 			ima_log_string(ab, "appraise_flag", args[0].from);
-			if (strstr(args[0].from, "blacklist"))
+			if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
+			    strstr(args[0].from, "blacklist"))
 				entry->flags |= IMA_CHECK_BLACKLIST;
+			else
+				result = -EINVAL;
 			break;
 		case Opt_permit_directio:
 			entry->flags |= IMA_PERMIT_DIRECTIO;
 			break;
 		case Opt_pcr:
-			if (entry->action != MEASURE) {
-				result = -EINVAL;
-				break;
-			}
 			ima_log_string(ab, "pcr", args[0].from);
 
 			result = kstrtoint(args[0].from, 10, &entry->pcr);
@@ -1332,7 +1432,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			break;
 		}
 	}
-	if (!result && (entry->action == UNKNOWN))
+	if (!result && !ima_validate_rule(entry))
 		result = -EINVAL;
 	else if (entry->action == APPRAISE)
 		temp_ima_appraise |= ima_appraise_flag(entry->func);
@@ -1381,7 +1481,7 @@ ssize_t ima_parse_add_rule(char *rule)
 
 	result = ima_parse_rule(p, entry);
 	if (result) {
-		kfree(entry);
+		ima_free_rule(entry);
 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 				    NULL, op, "invalid-policy", result,
 				    audit_info);
@@ -1402,19 +1502,15 @@ ssize_t ima_parse_add_rule(char *rule)
 void ima_delete_rules(void)
 {
 	struct ima_rule_entry *entry, *tmp;
-	int i;
 
 	temp_ima_appraise = 0;
 	list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
-		for (i = 0; i < MAX_LSM_RULES; i++)
-			kfree(entry->lsm[i].args_p);
-
 		list_del(&entry->list);
-		kfree(entry);
+		ima_free_rule(entry);
 	}
 }
 
-#define __ima_hook_stringify(str)	(#str),
+#define __ima_hook_stringify(func, str)	(#func),
 
 const char *const func_tokens[] = {
 	__ima_hooks(__ima_hook_stringify)
@@ -1589,27 +1685,27 @@ int ima_policy_show(struct seq_file *m, void *v)
 			switch (i) {
 			case LSM_OBJ_USER:
 				seq_printf(m, pt(Opt_obj_user),
-					   (char *)entry->lsm[i].args_p);
+					   entry->lsm[i].args_p);
 				break;
 			case LSM_OBJ_ROLE:
 				seq_printf(m, pt(Opt_obj_role),
-					   (char *)entry->lsm[i].args_p);
+					   entry->lsm[i].args_p);
 				break;
 			case LSM_OBJ_TYPE:
 				seq_printf(m, pt(Opt_obj_type),
-					   (char *)entry->lsm[i].args_p);
+					   entry->lsm[i].args_p);
 				break;
 			case LSM_SUBJ_USER:
 				seq_printf(m, pt(Opt_subj_user),
-					   (char *)entry->lsm[i].args_p);
+					   entry->lsm[i].args_p);
 				break;
 			case LSM_SUBJ_ROLE:
 				seq_printf(m, pt(Opt_subj_role),
-					   (char *)entry->lsm[i].args_p);
+					   entry->lsm[i].args_p);
 				break;
 			case LSM_SUBJ_TYPE:
 				seq_printf(m, pt(Opt_subj_type),
-					   (char *)entry->lsm[i].args_p);
+					   entry->lsm[i].args_p);
 				break;
 			}
 			seq_puts(m, " ");