netlink: remove NLA_EXACT_LEN_WARN

Use a validation type instead, so we can later expose
the NLA_* values to userspace for policy descriptions.

Some transformations were done with this spatch:

    @@
    identifier p;
    expression X, L, A;
    @@
    struct nla_policy p[X] = {
    [A] =
    -{ .type = NLA_EXACT_LEN_WARN, .len = L },
    +NLA_POLICY_EXACT_LEN_WARN(L),
    ...
    };

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 6 deletions

diff --git a/lib/nlattr.c b/lib/nlattr.c
index 21ef3998b9d9..6dcbe1bedd3b 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -261,7 +261,9 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 	BUG_ON(pt->type > NLA_TYPE_MAX);
 
 	if ((nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) ||
-	    (pt->type == NLA_EXACT_LEN_WARN && attrlen != pt->len)) {
+	    (pt->type == NLA_EXACT_LEN &&
+	     pt->validation_type == NLA_VALIDATE_WARN_TOO_LONG &&
+	     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) {
@@ -287,11 +289,6 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 	}
 
 	switch (pt->type) {
-	case NLA_EXACT_LEN:
-		if (attrlen != pt->len)
-			goto out_err;
-		break;
-
 	case NLA_REJECT:
 		if (extack && pt->reject_message) {
 			NL_SET_BAD_ATTR(extack, nla);
@@ -405,6 +402,13 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
 			goto out_err;
 		break;
 
+	case NLA_EXACT_LEN:
+		if (pt->validation_type != NLA_VALIDATE_WARN_TOO_LONG) {
+			if (attrlen != pt->len)
+				goto out_err;
+			break;
+		}
+		/* fall through */
 	default:
 		if (pt->len)
 			minlen = pt->len;