| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Fri, 26 Oct 2012 16:05:15 -0700
From: Stephen Hemminger <shemminger@...tta.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: [RFC] gretap: don't do MTU discovery
This came up during review of VXLAN.
Since gretap is a L2 tunnel, and it is not necessarily in the same IP
network space as there is no way to safely do MTU discovery.
The IP address in the inner header may not be reachable or conflict
with the IP address visible to the kernel.
Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
--- a/net/ipv4/ip_gre.c 2012-10-26 15:50:39.579955151 -0700
+++ b/net/ipv4/ip_gre.c 2012-10-26 15:58:31.667213979 -0700
@@ -765,7 +765,6 @@ static netdev_tx_t ipgre_tunnel_xmit(str
unsigned int max_headroom; /* The extra header space needed */
int gre_hlen;
__be32 dst;
- int mtu;
if (skb->ip_summed == CHECKSUM_PARTIAL &&
skb_checksum_help(skb))
@@ -853,44 +852,54 @@ static netdev_tx_t ipgre_tunnel_xmit(str
}
df = tiph->frag_off;
- if (df)
- mtu = dst_mtu(&rt->dst) - dev->hard_header_len - tunnel->hlen;
- else
- mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
-
- if (skb_dst(skb))
- skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);
-
- if (skb->protocol == htons(ETH_P_IP)) {
- df |= (old_iph->frag_off&htons(IP_DF));
-
- if ((old_iph->frag_off&htons(IP_DF)) &&
- mtu < ntohs(old_iph->tot_len)) {
- icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
- ip_rt_put(rt);
- goto tx_error;
+ if (dev->type == ARPHRD_IPGRE) {
+ unsigned int mtu;
+
+ if (df)
+ mtu = dst_mtu(&rt->dst)
+ - dev->hard_header_len - tunnel->hlen;
+ else
+ mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu;
+
+ if (skb_dst(skb))
+ skb_dst(skb)->ops->update_pmtu(skb_dst(skb),
+ NULL, skb, mtu);
+
+ if (skb->protocol == htons(ETH_P_IP)) {
+ df |= (old_iph->frag_off&htons(IP_DF));
+
+ if ((old_iph->frag_off&htons(IP_DF)) &&
+ mtu < ntohs(old_iph->tot_len)) {
+ icmp_send(skb, ICMP_DEST_UNREACH,
+ ICMP_FRAG_NEEDED, htonl(mtu));
+ ip_rt_put(rt);
+ goto tx_error;
+ }
}
- }
#if IS_ENABLED(CONFIG_IPV6)
- else if (skb->protocol == htons(ETH_P_IPV6)) {
- struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb);
+ else if (skb->protocol == htons(ETH_P_IPV6)) {
+ struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb);
- if (rt6 && mtu < dst_mtu(skb_dst(skb)) && mtu >= IPV6_MIN_MTU) {
- if ((tunnel->parms.iph.daddr &&
- !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||
- rt6->rt6i_dst.plen == 128) {
- rt6->rt6i_flags |= RTF_MODIFIED;
- dst_metric_set(skb_dst(skb), RTAX_MTU, mtu);
+ if (rt6 && mtu < dst_mtu(skb_dst(skb)) &&
+ mtu >= IPV6_MIN_MTU) {
+ if ((tunnel->parms.iph.daddr &&
+ !ipv4_is_multicast(tunnel->parms.iph.daddr)) ||
+ rt6->rt6i_dst.plen == 128) {
+ rt6->rt6i_flags |= RTF_MODIFIED;
+ dst_metric_set(skb_dst(skb),
+ RTAX_MTU, mtu);
+ }
}
- }
- if (mtu >= IPV6_MIN_MTU && mtu < skb->len - tunnel->hlen + gre_hlen) {
- icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
- ip_rt_put(rt);
- goto tx_error;
+ if (mtu >= IPV6_MIN_MTU &&
+ mtu < skb->len - tunnel->hlen + gre_hlen) {
+ icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+ ip_rt_put(rt);
+ goto tx_error;
+ }
}
- }
#endif
+ }
if (tunnel->err_count > 0) {
if (time_before(jiffies,
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists