#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/tcp.h>
+#include <net/dst.h>
+#include <net/flow.h>
#include <net/ipv6.h>
+#include <net/route.h>
#include <net/tcp.h>
#include <linux/netfilter_ipv4/ip_tables.h>
static int
tcpmss_mangle_packet(struct sk_buff *skb,
const struct xt_tcpmss_info *info,
+ unsigned int in_mtu,
unsigned int tcphoff,
unsigned int minlen)
{
tcplen = skb->len - tcphoff;
tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff);
- /* Since it passed flags test in tcp match, we know it is is
- not a fragment, and has data >= tcp header length. SYN
- packets should not contain data: if they did, then we risk
- running over MTU, sending Frag Needed and breaking things
- badly. --RR */
- if (tcplen != tcph->doff*4) {
- if (net_ratelimit())
- printk(KERN_ERR "xt_TCPMSS: bad length (%u bytes)\n",
- skb->len);
+ /* Header cannot be larger than the packet */
+ if (tcplen < tcph->doff*4)
return -1;
- }
if (info->mss == XT_TCPMSS_CLAMP_PMTU) {
- if (dst_mtu(skb->dst) <= minlen) {
+ if (dst_mtu(skb_dst(skb)) <= minlen) {
if (net_ratelimit())
printk(KERN_ERR "xt_TCPMSS: "
"unknown or invalid path-MTU (%u)\n",
- dst_mtu(skb->dst));
+ dst_mtu(skb_dst(skb)));
+ return -1;
+ }
+ if (in_mtu <= minlen) {
+ if (net_ratelimit())
+ printk(KERN_ERR "xt_TCPMSS: unknown or "
+ "invalid path-MTU (%u)\n", in_mtu);
return -1;
}
- newmss = dst_mtu(skb->dst) - minlen;
+ newmss = min(dst_mtu(skb_dst(skb)), in_mtu) - minlen;
} else
newmss = info->mss;
}
}
+ /* There is data after the header so the option can't be added
+ without moving it, and doing so may make the SYN packet
+ itself too large. Accept the packet unmodified instead. */
+ if (tcplen > tcph->doff*4)
+ return 0;
+
/*
* MSS Option not found ?! add it..
*/
return TCPOLEN_MSS;
}
+static u_int32_t tcpmss_reverse_mtu(const struct sk_buff *skb,
+ unsigned int family)
+{
+ struct flowi fl = {};
+ const struct nf_afinfo *ai;
+ struct rtable *rt = NULL;
+ u_int32_t mtu = ~0U;
+
+ if (family == PF_INET)
+ fl.fl4_dst = ip_hdr(skb)->saddr;
+ else
+ fl.fl6_dst = ipv6_hdr(skb)->saddr;
+
+ rcu_read_lock();
+ ai = nf_get_afinfo(family);
+ if (ai != NULL)
+ ai->route((struct dst_entry **)&rt, &fl);
+ rcu_read_unlock();
+
+ if (rt != NULL) {
+ mtu = dst_mtu(&rt->u.dst);
+ dst_release(&rt->u.dst);
+ }
+ return mtu;
+}
+
static unsigned int
-tcpmss_tg4(struct sk_buff *skb, const struct net_device *in,
- const struct net_device *out, unsigned int hooknum,
- const struct xt_target *target, const void *targinfo)
+tcpmss_tg4(struct sk_buff *skb, const struct xt_target_param *par)
{
struct iphdr *iph = ip_hdr(skb);
__be16 newlen;
int ret;
- ret = tcpmss_mangle_packet(skb, targinfo, iph->ihl * 4,
+ ret = tcpmss_mangle_packet(skb, par->targinfo,
+ tcpmss_reverse_mtu(skb, PF_INET),
+ iph->ihl * 4,
sizeof(*iph) + sizeof(struct tcphdr));
if (ret < 0)
return NF_DROP;
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
static unsigned int
-tcpmss_tg6(struct sk_buff *skb, const struct net_device *in,
- const struct net_device *out, unsigned int hooknum,
- const struct xt_target *target, const void *targinfo)
+tcpmss_tg6(struct sk_buff *skb, const struct xt_target_param *par)
{
struct ipv6hdr *ipv6h = ipv6_hdr(skb);
u8 nexthdr;
tcphoff = ipv6_skip_exthdr(skb, sizeof(*ipv6h), &nexthdr);
if (tcphoff < 0)
return NF_DROP;
- ret = tcpmss_mangle_packet(skb, targinfo, tcphoff,
+ ret = tcpmss_mangle_packet(skb, par->targinfo,
+ tcpmss_reverse_mtu(skb, PF_INET6),
+ tcphoff,
sizeof(*ipv6h) + sizeof(struct tcphdr));
if (ret < 0)
return NF_DROP;
return false;
}
-static bool
-tcpmss_tg4_check(const char *tablename, const void *entry,
- const struct xt_target *target, void *targinfo,
- unsigned int hook_mask)
+static bool tcpmss_tg4_check(const struct xt_tgchk_param *par)
{
- const struct xt_tcpmss_info *info = targinfo;
- const struct ipt_entry *e = entry;
+ const struct xt_tcpmss_info *info = par->targinfo;
+ const struct ipt_entry *e = par->entryinfo;
if (info->mss == XT_TCPMSS_CLAMP_PMTU &&
- (hook_mask & ~((1 << NF_INET_FORWARD) |
+ (par->hook_mask & ~((1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING))) != 0) {
printk("xt_TCPMSS: path-MTU clamping only supported in "
}
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
-static bool
-tcpmss_tg6_check(const char *tablename, const void *entry,
- const struct xt_target *target, void *targinfo,
- unsigned int hook_mask)
+static bool tcpmss_tg6_check(const struct xt_tgchk_param *par)
{
- const struct xt_tcpmss_info *info = targinfo;
- const struct ip6t_entry *e = entry;
+ const struct xt_tcpmss_info *info = par->targinfo;
+ const struct ip6t_entry *e = par->entryinfo;
if (info->mss == XT_TCPMSS_CLAMP_PMTU &&
- (hook_mask & ~((1 << NF_INET_FORWARD) |
+ (par->hook_mask & ~((1 << NF_INET_FORWARD) |
(1 << NF_INET_LOCAL_OUT) |
(1 << NF_INET_POST_ROUTING))) != 0) {
printk("xt_TCPMSS: path-MTU clamping only supported in "
static struct xt_target tcpmss_tg_reg[] __read_mostly = {
{
- .family = AF_INET,
+ .family = NFPROTO_IPV4,
.name = "TCPMSS",
.checkentry = tcpmss_tg4_check,
.target = tcpmss_tg4,
},
#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
{
- .family = AF_INET6,
+ .family = NFPROTO_IPV6,
.name = "TCPMSS",
.checkentry = tcpmss_tg6_check,
.target = tcpmss_tg6,
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff