| Message ID | 1609854201-30143-1-git-send-email-ayal@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,V2] net: ipv6: Validate GSO SKB before finish IPv6 processing | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 4 maintainers not CCed: jengelh@medozas.de kaber@trash.net kuznet@ms2.inr.ac.ru yoshfuji@linux-ipv6.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 43 this patch: 43 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 55 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 35 this patch: 35 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On Tue, 5 Jan 2021 15:43:21 +0200 Aya Levin wrote: > There are cases where GSO segment's length exceeds the egress MTU. Please name same for posterity. Please widen the CC list. > If so: > - Consume the SKB and its segments. > - Issue an ICMP packet with 'Packet Too Big' message containing the > MTU, allowing the source host to reduce its Path MTU appropriately. > > Note: These cases are handled in the same manner in IPv4 output finish. > This patch aligns the behavior of IPv6 and the one of IPv4. > > Fixes: 9e50849054a4 ("netfilter: ipv6: move POSTROUTING invocation before fragmentation") Not sure if this commit actually adds the problem or just moves the problematic snippet around. But probably doesn't matter that much for 10+ years old code. > Signed-off-by: Aya Levin <ayal@nvidia.com> > Reviewed-by: Tariq Toukan <tariqt@nvidia.com> The code itself looks reasonable AFAICT.
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 749ad72386b2..077d43af8226 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -125,8 +125,43 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * return -EINVAL; } +static int +ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk, + struct sk_buff *skb, unsigned int mtu) +{ + struct sk_buff *segs, *nskb; + netdev_features_t features; + int ret = 0; + + /* Please see corresponding comment in ip_finish_output_gso + * describing the cases where GSO segment length exceeds the + * egress MTU. + */ + features = netif_skb_features(skb); + segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); + if (IS_ERR_OR_NULL(segs)) { + kfree_skb(skb); + return -ENOMEM; + } + + consume_skb(skb); + + skb_list_walk_safe(segs, segs, nskb) { + int err; + + skb_mark_not_on_list(segs); + err = ip6_fragment(net, sk, segs, ip6_finish_output2); + if (err && ret == 0) + ret = err; + } + + return ret; +} + static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb) { + unsigned int mtu; + #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) /* Policy lookup after SNAT yielded a new policy */ if (skb_dst(skb)->xfrm) { @@ -135,7 +170,11 @@ static int __ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff } #endif - if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) || + mtu = ip6_skb_dst_mtu(skb); + if (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu)) + return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu); + + if ((skb->len > mtu && !skb_is_gso(skb)) || dst_allfrag(skb_dst(skb)) || (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size)) return ip6_fragment(net, sk, skb, ip6_finish_output2);
There are cases where GSO segment's length exceeds the egress MTU. If so: - Consume the SKB and its segments. - Issue an ICMP packet with 'Packet Too Big' message containing the MTU, allowing the source host to reduce its Path MTU appropriately. Note: These cases are handled in the same manner in IPv4 output finish. This patch aligns the behavior of IPv6 and the one of IPv4. Fixes: 9e50849054a4 ("netfilter: ipv6: move POSTROUTING invocation before fragmentation") Signed-off-by: Aya Levin <ayal@nvidia.com> Reviewed-by: Tariq Toukan <tariqt@nvidia.com> --- net/ipv6/ip6_output.c | 41 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) Hi, Please queue to -stable >= v2.6.35. Thanks, Aya v2: Addressed error: uninitialized symbol 'ret', reported by kernel test robot <lkp@intel.com> / Dan Carpenter <dan.carpenter@oracle.com>.