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author | David S. Miller <davem@davemloft.net> | 2013-06-17 23:13:45 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2013-06-17 23:13:45 (GMT) |
commit | e00c7f1fad21ff81ac0a8dfbbb7cc3b7c806fa73 (patch) | |
tree | 12e29890b5feb323c762abf28d2c1b6ff217c0fa /net | |
parent | ab69bde6b2e9c37456eeb0051a185446336aef9f (diff) | |
parent | b396966c4688522863572927cb30aa874b3ec504 (diff) | |
download | linux-e00c7f1fad21ff81ac0a8dfbbb7cc3b7c806fa73.tar.xz |
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: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r-- | net/netfilter/xt_TCPMSS.c | 25 | ||||
-rw-r--r-- | net/netfilter/xt_TCPOPTSTRIP.c | 6 |
2 files changed, 22 insertions, 9 deletions
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c index afaebc7..7011c71 100644 --- a/net/netfilter/xt_TCPMSS.c +++ b/net/netfilter/xt_TCPMSS.c @@ -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)); diff --git a/net/netfilter/xt_TCPOPTSTRIP.c b/net/netfilter/xt_TCPOPTSTRIP.c index 1eb1a44..b68fa19 100644 --- a/net/netfilter/xt_TCPOPTSTRIP.c +++ b/net/netfilter/xt_TCPOPTSTRIP.c @@ -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; /* |