netfilter: nfnetlink: cleanup for nfnetlink_rcv_msg() function

This patch cleans up the message handling path in two aspects:

 * it uses NLMSG_LENGTH() instead of NLMSG_SPACE() like rtnetlink
does in this case to check if there is enough room for the
Netlink/nfnetlink headers. No need to check for the padding room.

 * it removes a redundant header size checking that has been
 already do at the beginning of the function.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index b8ab37ad7ed56f60978d3827c31d722654c74fe0..9dbd5709aad745b8bd09a3ebc08b5bd963a0fdbf 100644 (file)
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -136,7 +136,7 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
                return -EPERM;
 
        /* All the messages must at least contain nfgenmsg */
-       if (nlh->nlmsg_len < NLMSG_SPACE(sizeof(struct nfgenmsg)))
+       if (nlh->nlmsg_len < NLMSG_LENGTH(sizeof(struct nfgenmsg)))
                return 0;
 
        type = nlh->nlmsg_type;
@@ -160,19 +160,14 @@ replay:
        {
                int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
                u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
-               u_int16_t attr_count = ss->cb[cb_id].attr_count;
-               struct nlattr *cda[attr_count+1];
-
-               if (likely(nlh->nlmsg_len >= min_len)) {
-                       struct nlattr *attr = (void *)nlh + NLMSG_ALIGN(min_len);
-                       int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
-
-                       err = nla_parse(cda, attr_count, attr, attrlen,
-                                       ss->cb[cb_id].policy);
-                       if (err < 0)
-                               return err;
-               } else
-                       return -EINVAL;
+               struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
+               struct nlattr *attr = (void *)nlh + min_len;
+               int attrlen = nlh->nlmsg_len - min_len;
+
+               err = nla_parse(cda, ss->cb[cb_id].attr_count,
+                               attr, attrlen, ss->cb[cb_id].policy);
+               if (err < 0)
+                       return err;
 
                err = nc->call(nfnl, skb, nlh, cda);
                if (err == -EAGAIN)