[NETFILTER] nfnetlink: use highest bit of nfa_type to indicate nested TLV

As Henrik Nordstrom pointed out, all our efforts with "split endian" (i.e.
host byte order tags, net byte order values) are useless, unless a parser
can determine whether an attribute is nested or not.

This patch steals the highest bit of nfattr.nfa_type to indicate whether
the data payload contains a nested nfattr (1) or not (0).

This will break userspace compatibility, but luckily no kernel with
nfnetlink was released so far.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 1caaca06f698..4bc27a6334c1 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -133,7 +133,7 @@ int nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
         memset(tb, 0, sizeof(struct nfattr *) * maxattr);
 
         while (NFA_OK(nfa, len)) {
-                unsigned flavor = nfa->nfa_type;
+                unsigned flavor = NFA_TYPE(nfa);
                 if (flavor && flavor <= maxattr)
                         tb[flavor-1] = nfa;
                 nfa = NFA_NEXT(nfa, len);
@@ -177,7 +177,7 @@ nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
                 int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
 
                 while (NFA_OK(attr, attrlen)) {
-                        unsigned flavor = attr->nfa_type;
+                        unsigned flavor = NFA_TYPE(attr);
                         if (flavor) {
                                 if (flavor > attr_count)
                                         return -EINVAL;