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>

1 files changed, 9 insertions, 14 deletions

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index b8ab37ad7ed5..9dbd5709aad7 100644
--- 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)