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

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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2013-06-17 16:13:45 -07:00
commit e00c7f1fad
2 changed files with 22 additions and 9 deletions
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25
net/netfilter/xt_TCPMSS.c
View File

@ -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
*/
newmss = min(newmss, (u16)536);
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));

6
net/netfilter/xt_TCPOPTSTRIP.c
View File

@ -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;
/*