[NETFILTER]: nfnetlink: parse attributes with nfattr_parse in nfnetlink_check_attribute

Use nfattr_parse to parse attributes, this patch also modifies the default
behaviour since unknown attributes will be ignored instead of returning
EINVAL. This ensure backward compatibility: new libraries with new
attributes and old kernels can work.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 14 deletions

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 9ba6aa486f35..dec36abdf949 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -151,26 +151,14 @@ nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
                            struct nlmsghdr *nlh, struct nfattr *cda[])
 {
         int min_len = NLMSG_SPACE(sizeof(struct nfgenmsg));
-        u_int16_t attr_count;
         u_int8_t cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
-
-        attr_count = subsys->cb[cb_id].attr_count;
-        memset(cda, 0, sizeof(struct nfattr *) * attr_count);
+        u_int16_t attr_count = subsys->cb[cb_id].attr_count;
 
         /* check attribute lengths. */
         if (likely(nlh->nlmsg_len > min_len)) {
                 struct nfattr *attr = NFM_NFA(NLMSG_DATA(nlh));
                 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
-
-                while (NFA_OK(attr, attrlen)) {
-                        unsigned flavor = NFA_TYPE(attr);
-                        if (flavor) {
-                                if (flavor > attr_count)
-                                        return -EINVAL;
-                                cda[flavor - 1] = attr;
-                        }
-                        attr = NFA_NEXT(attr, attrlen);
-                }
+                nfattr_parse(cda, attr_count, attr, attrlen);
         }
 
         /* implicit: if nlmsg_len == min_len, we return 0, and an empty