Commit e00c7f1f authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 



Pablo Neira Ayuso says:

====================
The following patchset contains Netfilter fixes. They are targeted to the
TCP option targets, that have receive some scrinity in the last week. The
changes are:

* Fix TCPOPTSTRIP, it stopped working in the forward chain as tcp_hdr
  uses skb->transport_header, and we cannot use that in the forwarding
  case, from myself.

* Fix default IPv6 MSS in TCPMSS in case of absence of TCP MSS options,
  from Phil Oester.

* Fix missing fragmentation handling again in TCPMSS, from Phil Oester.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents ab69bde6 b396966c

net/netfilter/xt_TCPMSS.c

+18 −7
Original line number Diff line number Diff line
@@ -45,17 +45,22 @@ optlen(const u_int8_t *opt, unsigned int offset) 


static int

tcpmss_mangle_packet(struct sk_buff *skb,

		     const struct xt_tcpmss_info *info,

		     const struct xt_action_param *par,

		     unsigned int in_mtu,

		     unsigned int tcphoff,

		     unsigned int minlen)

{

	const struct xt_tcpmss_info *info = par->targinfo;

	struct tcphdr *tcph;

	unsigned int tcplen, i;

	__be16 oldval;

	u16 newmss;

	u8 *opt;



	/* This is a fragment, no TCP header is available */

	if (par->fragoff != 0)

		return XT_CONTINUE;



	if (!skb_make_writable(skb, skb->len))

		return -1;
@@ -125,11 +130,17 @@ tcpmss_mangle_packet(struct sk_buff *skb, 


	skb_put(skb, TCPOLEN_MSS);



	/* RFC 879 states that the default MSS is 536 without specific

	 * knowledge that the destination host is prepared to accept larger.

	 * Since no MSS was provided, we MUST NOT set a value > 536.

	/*

	 * IPv4: RFC 1122 states "If an MSS option is not received at

	 * connection setup, TCP MUST assume a default send MSS of 536".

	 * IPv6: RFC 2460 states IPv6 has a minimum MTU of 1280 and a minimum

	 * length IPv6 header of 60, ergo the default MSS value is 1220

	 * Since no MSS was provided, we must use the default values

	 */

	if (par->family == NFPROTO_IPV4)

		newmss = min(newmss, (u16)536);

	else

		newmss = min(newmss, (u16)1220);



	opt = (u_int8_t *)tcph + sizeof(struct tcphdr);

	memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr));
@@ -188,7 +199,7 @@ tcpmss_tg4(struct sk_buff *skb, const struct xt_action_param *par) 
	__be16 newlen;

	int ret;



	ret = tcpmss_mangle_packet(skb, par->targinfo,

	ret = tcpmss_mangle_packet(skb, par,

				   tcpmss_reverse_mtu(skb, PF_INET),

				   iph->ihl * 4,

				   sizeof(*iph) + sizeof(struct tcphdr));
@@ -217,7 +228,7 @@ tcpmss_tg6(struct sk_buff *skb, const struct xt_action_param *par) 
	tcphoff = ipv6_skip_exthdr(skb, sizeof(*ipv6h), &nexthdr, &frag_off);

	if (tcphoff < 0)

		return NF_DROP;

	ret = tcpmss_mangle_packet(skb, par->targinfo,

	ret = tcpmss_mangle_packet(skb, par,

				   tcpmss_reverse_mtu(skb, PF_INET6),

				   tcphoff,

				   sizeof(*ipv6h) + sizeof(struct tcphdr));

net/netfilter/xt_TCPOPTSTRIP.c

+4 −2
Original line number Diff line number Diff line
@@ -48,11 +48,13 @@ tcpoptstrip_mangle_packet(struct sk_buff *skb, 
		return NF_DROP;



	len = skb->len - tcphoff;

	if (len < (int)sizeof(struct tcphdr) ||

	    tcp_hdr(skb)->doff * 4 > len)

	if (len < (int)sizeof(struct tcphdr))

		return NF_DROP;



	tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff);

	if (tcph->doff * 4 > len)

		return NF_DROP;



	opt  = (u_int8_t *)tcph;



	/*

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