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authorDavid S. Miller <davem@davemloft.net>2013-06-17 16:13:45 -0700
committerDavid S. Miller <davem@davemloft.net>2013-06-17 16:13:45 -0700
commite00c7f1fad21ff81ac0a8dfbbb7cc3b7c806fa73 (patch)
tree12e29890b5feb323c762abf28d2c1b6ff217c0fa /net
parentab69bde6b2e9c37456eeb0051a185446336aef9f (diff)
parentb396966c4688522863572927cb30aa874b3ec504 (diff)
downloadlinux-e00c7f1fad21ff81ac0a8dfbbb7cc3b7c806fa73.tar.bz2
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.c25
-rw-r--r--net/netfilter/xt_TCPOPTSTRIP.c6
2 files changed, 22 insertions, 9 deletions
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index afaebc766933..7011c71646f0 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 1eb1a44bfd3d..b68fa191710f 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;
/*