| Message ID | 1373387377-23413-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c index 71a266d..4960b66 100644 --- a/net/netfilter/xt_TCPMSS.c +++ b/net/netfilter/xt_TCPMSS.c @@ -124,6 +124,12 @@ 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. + */ + newmss = min(newmss, (u16)536); + opt = (u_int8_t *)tcph + sizeof(struct tcphdr); memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr));
This is a note to let you know that I have just added a patch titled netfilter: xt_TCPMSS: Fix violation of RFC879 in absence of to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From b00a45085e067d8e584759806dbe57eacb165a30 Mon Sep 17 00:00:00 2001 From: Phil Oester <kernel@linuxace.com> Date: Tue, 4 Jun 2013 05:09:27 +0000 Subject: [PATCH] netfilter: xt_TCPMSS: Fix violation of RFC879 in absence of MSS option commit 409b545ac10d9548929557a75ad86540f59a2c83 upstream. The clamp-mss-to-pmtu option of the xt_TCPMSS target can cause issues connecting to websites if there was no MSS option present in the original SYN packet from the client. In these cases, it may add a MSS higher than the default specified in RFC879. Fix this by never setting a value > 536 if no MSS option was specified by the client. This closes netfilter's bugzilla #662. Signed-off-by: Phil Oester <kernel@linuxace.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/netfilter/xt_TCPMSS.c | 6 ++++++ 1 file changed, 6 insertions(+) -- 1.8.1.2