1 files changed, 116 insertions, 84 deletions

diff --git a/lib/nlattr.c b/lib/nlattr.c
index d26de6156b97..cace9b307781 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -69,7 +69,8 @@ static int validate_nla_bitfield32(const struct nlattr *nla,
 
 static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
 			      const struct nla_policy *policy,
-			      struct netlink_ext_ack *extack)
+			      struct netlink_ext_ack *extack,
+			      unsigned int validate)
 {
 	const struct nlattr *entry;
 	int rem;
@@ -86,8 +87,8 @@ static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
 			return -ERANGE;
 		}
 
-		ret = nla_validate(nla_data(entry), nla_len(entry),
-				   maxtype, policy, extack);
+		ret = __nla_validate(nla_data(entry), nla_len(entry),
+				     maxtype, policy, validate, extack);
 		if (ret < 0)
 			return ret;
 	}
@@ -154,13 +155,17 @@ static int nla_validate_int_range(const struct nla_policy *pt,
 }
 
 static int validate_nla(const struct nlattr *nla, int maxtype,
-			const struct nla_policy *policy,
+			const struct nla_policy *policy, unsigned int validate,
 			struct netlink_ext_ack *extack)
 {
+	u16 strict_start_type = policy[0].strict_start_type;
 	const struct nla_policy *pt;
 	int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
 	int err = -ERANGE;
 
+	if (strict_start_type && type >= strict_start_type)
+		validate |= NL_VALIDATE_STRICT;
+
 	if (type <= 0 || type > maxtype)
 		return 0;
 
@@ -172,6 +177,26 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 	    (pt->type == NLA_EXACT_LEN_WARN && attrlen != pt->len)) {
 		pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
 				    current->comm, type);
+		if (validate & NL_VALIDATE_STRICT_ATTRS) {
+			NL_SET_ERR_MSG_ATTR(extack, nla,
+					    "invalid attribute length");
+			return -EINVAL;
+		}
+	}
+
+	if (validate & NL_VALIDATE_NESTED) {
+		if ((pt->type == NLA_NESTED || pt->type == NLA_NESTED_ARRAY) &&
+		    !(nla->nla_type & NLA_F_NESTED)) {
+			NL_SET_ERR_MSG_ATTR(extack, nla,
+					    "NLA_F_NESTED is missing");
+			return -EINVAL;
+		}
+		if (pt->type != NLA_NESTED && pt->type != NLA_NESTED_ARRAY &&
+		    pt->type != NLA_UNSPEC && (nla->nla_type & NLA_F_NESTED)) {
+			NL_SET_ERR_MSG_ATTR(extack, nla,
+					    "NLA_F_NESTED not expected");
+			return -EINVAL;
+		}
 	}
 
 	switch (pt->type) {
@@ -244,8 +269,9 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 		if (attrlen < NLA_HDRLEN)
 			goto out_err;
 		if (pt->validation_data) {
-			err = nla_validate(nla_data(nla), nla_len(nla), pt->len,
-					   pt->validation_data, extack);
+			err = __nla_validate(nla_data(nla), nla_len(nla), pt->len,
+					     pt->validation_data, validate,
+					     extack);
 			if (err < 0) {
 				/*
 				 * return directly to preserve the inner
@@ -268,7 +294,7 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 
 			err = nla_validate_array(nla_data(nla), nla_len(nla),
 						 pt->len, pt->validation_data,
-						 extack);
+						 extack, validate);
 			if (err < 0) {
 				/*
 				 * return directly to preserve the inner
@@ -278,10 +304,23 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 			}
 		}
 		break;
+
+	case NLA_UNSPEC:
+		if (validate & NL_VALIDATE_UNSPEC) {
+			NL_SET_ERR_MSG_ATTR(extack, nla,
+					    "Unsupported attribute");
+			return -EINVAL;
+		}
+		/* fall through */
+	case NLA_MIN_LEN:
+		if (attrlen < pt->len)
+			goto out_err;
+		break;
+
 	default:
 		if (pt->len)
 			minlen = pt->len;
-		else if (pt->type != NLA_UNSPEC)
+		else
 			minlen = nla_attr_minlen[pt->type];
 
 		if (attrlen < minlen)
@@ -315,37 +354,76 @@ out_err:
 	return err;
 }
 
+static int __nla_validate_parse(const struct nlattr *head, int len, int maxtype,
+				const struct nla_policy *policy,
+				unsigned int validate,
+				struct netlink_ext_ack *extack,
+				struct nlattr **tb)
+{
+	const struct nlattr *nla;
+	int rem;
+
+	if (tb)
+		memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
+
+	nla_for_each_attr(nla, head, len, rem) {
+		u16 type = nla_type(nla);
+
+		if (type == 0 || type > maxtype) {
+			if (validate & NL_VALIDATE_MAXTYPE) {
+				NL_SET_ERR_MSG_ATTR(extack, nla,
+						    "Unknown attribute type");
+				return -EINVAL;
+			}
+			continue;
+		}
+		if (policy) {
+			int err = validate_nla(nla, maxtype, policy,
+					       validate, extack);
+
+			if (err < 0)
+				return err;
+		}
+
+		if (tb)
+			tb[type] = (struct nlattr *)nla;
+	}
+
+	if (unlikely(rem > 0)) {
+		pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
+				    rem, current->comm);
+		NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
+		if (validate & NL_VALIDATE_TRAILING)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
 /**
- * nla_validate - Validate a stream of attributes
+ * __nla_validate - Validate a stream of attributes
  * @head: head of attribute stream
  * @len: length of attribute stream
  * @maxtype: maximum attribute type to be expected
  * @policy: validation policy
+ * @validate: validation strictness
  * @extack: extended ACK report struct
  *
  * Validates all attributes in the specified attribute stream against the
- * specified policy. Attributes with a type exceeding maxtype will be
- * ignored. See documenation of struct nla_policy for more details.
+ * specified policy. Validation depends on the validate flags passed, see
+ * &enum netlink_validation for more details on that.
+ * See documenation of struct nla_policy for more details.
  *
  * Returns 0 on success or a negative error code.
  */
-int nla_validate(const struct nlattr *head, int len, int maxtype,
-		 const struct nla_policy *policy,
-		 struct netlink_ext_ack *extack)
+int __nla_validate(const struct nlattr *head, int len, int maxtype,
+		   const struct nla_policy *policy, unsigned int validate,
+		   struct netlink_ext_ack *extack)
 {
-	const struct nlattr *nla;
-	int rem;
-
-	nla_for_each_attr(nla, head, len, rem) {
-		int err = validate_nla(nla, maxtype, policy, extack);
-
-		if (err < 0)
-			return err;
-	}
-
-	return 0;
+	return __nla_validate_parse(head, len, maxtype, policy, validate,
+				    extack, NULL);
 }
-EXPORT_SYMBOL(nla_validate);
+EXPORT_SYMBOL(__nla_validate);
 
 /**
  * nla_policy_len - Determin the max. length of a policy
@@ -377,76 +455,30 @@ nla_policy_len(const struct nla_policy *p, int n)
 EXPORT_SYMBOL(nla_policy_len);
 
 /**
- * nla_parse - Parse a stream of attributes into a tb buffer
+ * __nla_parse - Parse a stream of attributes into a tb buffer
  * @tb: destination array with maxtype+1 elements
  * @maxtype: maximum attribute type to be expected
  * @head: head of attribute stream
  * @len: length of attribute stream
  * @policy: validation policy
+ * @validate: validation strictness
+ * @extack: extended ACK pointer
  *
  * Parses a stream of attributes and stores a pointer to each attribute in
- * the tb array accessible via the attribute type. Attributes with a type
- * exceeding maxtype will be silently ignored for backwards compatibility
- * reasons. policy may be set to NULL if no validation is required.
+ * the tb array accessible via the attribute type.
+ * Validation is controlled by the @validate parameter.
  *
  * Returns 0 on success or a negative error code.
  */
-static int __nla_parse(struct nlattr **tb, int maxtype,
-		       const struct nlattr *head, int len,
-		       bool strict, const struct nla_policy *policy,
-		       struct netlink_ext_ack *extack)
-{
-	const struct nlattr *nla;
-	int rem;
-
-	memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
-
-	nla_for_each_attr(nla, head, len, rem) {
-		u16 type = nla_type(nla);
-
-		if (type == 0 || type > maxtype) {
-			if (strict) {
-				NL_SET_ERR_MSG(extack, "Unknown attribute type");
-				return -EINVAL;
-			}
-			continue;
-		}
-		if (policy) {
-			int err = validate_nla(nla, maxtype, policy, extack);
-
-			if (err < 0)
-				return err;
-		}
-
-		tb[type] = (struct nlattr *)nla;
-	}
-
-	if (unlikely(rem > 0)) {
-		pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
-				    rem, current->comm);
-		NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
-		if (strict)
-			return -EINVAL;
-	}
-
-	return 0;
-}
-
-int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
-	      int len, const struct nla_policy *policy,
-	      struct netlink_ext_ack *extack)
-{
-	return __nla_parse(tb, maxtype, head, len, false, policy, extack);
-}
-EXPORT_SYMBOL(nla_parse);
-
-int nla_parse_strict(struct nlattr **tb, int maxtype, const struct nlattr *head,
-		     int len, const struct nla_policy *policy,
-		     struct netlink_ext_ack *extack)
+int __nla_parse(struct nlattr **tb, int maxtype,
+		const struct nlattr *head, int len,
+		const struct nla_policy *policy, unsigned int validate,
+		struct netlink_ext_ack *extack)
 {
-	return __nla_parse(tb, maxtype, head, len, true, policy, extack);
+	return __nla_validate_parse(head, len, maxtype, policy, validate,
+				    extack, tb);
 }
-EXPORT_SYMBOL(nla_parse_strict);
+EXPORT_SYMBOL(__nla_parse);
 
 /**
  * nla_find - Find a specific attribute in a stream of attributes