From c8b37154268611691b395e4dd19a3bf1a87d57ef Mon Sep 17 00:00:00 2001 From: Phil Oester Date: Wed, 12 Jun 2013 10:58:20 +0200 Subject: [PATCH] netfilter: xt_TCPMSS: Fix missing fragmentation handling commit b396966c4688522863572927cb30aa874b3ec504 upstream. Similar to commit bc6bcb59 ("netfilter: xt_TCPOPTSTRIP: fix possible mangling beyond packet boundary"), add safe fragment handling to xt_TCPMSS. Signed-off-by: Phil Oester Signed-off-by: Pablo Neira Ayuso [bwh: Backported to 3.2: Change parameters for tcpmss_mangle_packet() as done upstream in commit 70d19f805f8c "netfilter: xt_TCPMSS: Fix IPv6 default MSS too"] Signed-off-by: Ben Hutchings --- net/netfilter/xt_TCPMSS.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c index 9e63b43faeed..3bbe241e0de8 100644 --- a/net/netfilter/xt_TCPMSS.c +++ b/net/netfilter/xt_TCPMSS.c @@ -44,17 +44,22 @@ 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; @@ -183,7 +188,7 @@ 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)); @@ -211,7 +216,7 @@ tcpmss_tg6(struct sk_buff *skb, const struct xt_action_param *par) tcphoff = ipv6_skip_exthdr(skb, sizeof(*ipv6h), &nexthdr); 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)); -- 2.39.5