3.2.62-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
This reverts commit caa5344994778a2b4725b2d75c74430f76925e4a, which
was commit fe6cc55f3a9a053482a76f5a6b2257cee51b4663 upstream. In 3.2,
the transport header length is not calculated in the forwarding path,
so skb_gso_network_seglen() returns an incorrect result. We also have
problems due to the local_df flag not being set correctly.
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
include/linux/skbuff.h | 17 -------------
net/ipv4/ip_forward.c | 68 ++------------------------------------------------
net/ipv6/ip6_output.c | 13 +---------
3 files changed, 3 insertions(+), 95 deletions(-)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2583,22 +2583,5 @@ static inline bool skb_is_recycleable(co
return true;
}
-
-/**
- * skb_gso_network_seglen - Return length of individual segments of a gso packet
- *
- * @skb: GSO skb
- *
- * skb_gso_network_seglen is used to determine the real size of the
- * individual segments, including Layer3 (IP, IPv6) and L4 headers (TCP/UDP).
- *
- * The MAC/L2 header is not accounted for.
- */
-static inline unsigned int skb_gso_network_seglen(const struct sk_buff *skb)
-{
- unsigned int hdr_len = skb_transport_header(skb) -
- skb_network_header(skb);
- return hdr_len + skb_gso_transport_seglen(skb);
-}
#endif /* __KERNEL__ */
#endif /* _LINUX_SKBUFF_H */
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -39,68 +39,6 @@
#include <net/route.h>
#include <net/xfrm.h>
-static bool ip_may_fragment(const struct sk_buff *skb)
-{
- return unlikely((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0) ||
- !skb->local_df;
-}
-
-static bool ip_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
-{
- if (skb->len <= mtu || skb->local_df)
- return false;
-
- if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
- return false;
-
- return true;
-}
-
-static bool ip_gso_exceeds_dst_mtu(const struct sk_buff *skb)
-{
- unsigned int mtu;
-
- if (skb->local_df || !skb_is_gso(skb))
- return false;
-
- mtu = dst_mtu(skb_dst(skb));
-
- /* if seglen > mtu, do software segmentation for IP fragmentation on
- * output. DF bit cannot be set since ip_forward would have sent
- * icmp error.
- */
- return skb_gso_network_seglen(skb) > mtu;
-}
-
-/* called if GSO skb needs to be fragmented on forward */
-static int ip_forward_finish_gso(struct sk_buff *skb)
-{
- struct sk_buff *segs;
- int ret = 0;
-
- segs = skb_gso_segment(skb, 0);
- if (IS_ERR(segs)) {
- kfree_skb(skb);
- return -ENOMEM;
- }
-
- consume_skb(skb);
-
- do {
- struct sk_buff *nskb = segs->next;
- int err;
-
- segs->next = NULL;
- err = dst_output(segs);
-
- if (err && ret == 0)
- ret = err;
- segs = nskb;
- } while (segs);
-
- return ret;
-}
-
static int ip_forward_finish(struct sk_buff *skb)
{
struct ip_options * opt = &(IPCB(skb)->opt);
@@ -110,9 +48,6 @@ static int ip_forward_finish(struct sk_b
if (unlikely(opt->optlen))
ip_forward_options(skb);
- if (ip_gso_exceeds_dst_mtu(skb))
- return ip_forward_finish_gso(skb);
-
return dst_output(skb);
}
@@ -152,7 +87,8 @@ int ip_forward(struct sk_buff *skb)
if (opt->is_strictroute && opt->nexthop != rt->rt_gateway)
goto sr_failed;
- if (!ip_may_fragment(skb) && ip_exceeds_mtu(skb, dst_mtu(&rt->dst))) {
+ if (unlikely(skb->len > dst_mtu(&rt->dst) && !skb_is_gso(skb) &&
+ (ip_hdr(skb)->frag_off & htons(IP_DF))) && !skb->local_df) {
IP_INC_STATS(dev_net(rt->dst.dev), IPSTATS_MIB_FRAGFAILS);
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(dst_mtu(&rt->dst)));
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -381,17 +381,6 @@ static inline int ip6_forward_finish(str
return dst_output(skb);
}
-static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
-{
- if (skb->len <= mtu || skb->local_df)
- return false;
-
- if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu)
- return false;
-
- return true;
-}
-
int ip6_forward(struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
@@ -515,7 +504,7 @@ int ip6_forward(struct sk_buff *skb)
if (mtu < IPV6_MIN_MTU)
mtu = IPV6_MIN_MTU;
- if (ip6_pkt_too_big(skb, mtu)) {
+ if (skb->len > mtu && !skb_is_gso(skb)) {
/* Again, force OUTPUT device used as source address */
skb->dev = dst->dev;
icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
--
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