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[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>
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@ -41,11 +41,15 @@ enum nfnetlink_groups {
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struct nfattr
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{
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u_int16_t nfa_len;
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u_int16_t nfa_type;
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u_int16_t nfa_type; /* we use 15 bits for the type, and the highest
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* bit to indicate whether the payload is nested */
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} __attribute__ ((packed));
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/* FIXME: Shamelessly copy and pasted from rtnetlink.h, it's time
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* to put this in a generic file */
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/* FIXME: Apart from NFNL_NFA_NESTED shamelessly copy and pasted from
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* rtnetlink.h, it's time to put this in a generic file */
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#define NFNL_NFA_NEST 0x8000
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#define NFA_TYPE(attr) ((attr)->nfa_type & 0x7fff)
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#define NFA_ALIGNTO 4
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#define NFA_ALIGN(len) (((len) + NFA_ALIGNTO - 1) & ~(NFA_ALIGNTO - 1))
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@ -59,7 +63,7 @@ struct nfattr
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#define NFA_PAYLOAD(nfa) ((int)((nfa)->nfa_len) - NFA_LENGTH(0))
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#define NFA_NEST(skb, type) \
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({ struct nfattr *__start = (struct nfattr *) (skb)->tail; \
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NFA_PUT(skb, type, 0, NULL); \
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NFA_PUT(skb, (NFNL_NFA_NEST | type), 0, NULL); \
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__start; })
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#define NFA_NEST_END(skb, start) \
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({ (start)->nfa_len = ((skb)->tail - (unsigned char *) (start)); \
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@ -133,7 +133,7 @@ int nfattr_parse(struct nfattr *tb[], int maxattr, struct nfattr *nfa, int len)
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memset(tb, 0, sizeof(struct nfattr *) * maxattr);
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while (NFA_OK(nfa, len)) {
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unsigned flavor = nfa->nfa_type;
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unsigned flavor = NFA_TYPE(nfa);
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if (flavor && flavor <= maxattr)
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tb[flavor-1] = nfa;
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nfa = NFA_NEXT(nfa, len);
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@ -177,7 +177,7 @@ nfnetlink_check_attributes(struct nfnetlink_subsystem *subsys,
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int attrlen = nlh->nlmsg_len - NLMSG_ALIGN(min_len);
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while (NFA_OK(attr, attrlen)) {
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unsigned flavor = attr->nfa_type;
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unsigned flavor = NFA_TYPE(attr);
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if (flavor) {
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if (flavor > attr_count)
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return -EINVAL;
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