From: Andy Zhou <[email protected]> Current ip_fragment() API assumes there is a netdev device attached to the skb. The MTU size is then derived from the attached device. However, skbs incoming from OVS vports do not have a netdevice attached, so it is not possible to query it for the MTU size.
This patch splits the original function into two pieces: The core fragmentation logic is now provided by ip_fragment_mtu(), The call back function with this API accepts two arguments: skb and an application specific pointer. ip_fragment() retains the original API, and it in turn calls ip_fragment_mtu() to do the work. Future patches will make use of the new ip_fragment_mtu() from OVS modules. Signed-off-by: Andy Zhou <[email protected]> --- include/net/ip.h | 3 ++ net/ipv4/ip_output.c | 113 ++++++++++++++++++++++++++++---------------------- 2 files changed, 66 insertions(+), 50 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index 025c61c..e73ac20 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -109,6 +109,9 @@ int ip_mr_input(struct sk_buff *skb); int ip_output(struct sock *sk, struct sk_buff *skb); int ip_mc_output(struct sock *sk, struct sk_buff *skb); int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)); +int ip_fragment_mtu(struct sk_buff *skb, unsigned int mtu, unsigned int ll_rs, + struct net_device *dev, void *output_arg, + int (*output)(struct sk_buff *, void *output_arg)); int ip_do_nat(struct sk_buff *skb); void ip_send_check(struct iphdr *ip); int __ip_local_out(struct sk_buff *skb); diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index d68199d..57ed8ef 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -472,54 +472,22 @@ static void ip_copy_metadata(struct sk_buff *to, struct sk_buff *from) skb_copy_secmark(to, from); } -/* - * This IP datagram is too large to be sent in one piece. Break it up into - * smaller pieces (each of size equal to IP header plus - * a block of the data of the original IP data part) that will yet fit in a - * single device frame, and queue such a frame for sending. - */ - -int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) +int ip_fragment_mtu(struct sk_buff *skb, unsigned int mtu, unsigned int ll_rs, + struct net_device *dev, void *output_arg, + int (*output)(struct sk_buff *, void *output_arg)) { struct iphdr *iph; int ptr; - struct net_device *dev; struct sk_buff *skb2; - unsigned int mtu, hlen, left, len, ll_rs; + unsigned int hlen, left, len; int offset; __be16 not_last_frag; - struct rtable *rt = skb_rtable(skb); int err = 0; - dev = rt->dst.dev; - - /* - * Point into the IP datagram header. - */ - iph = ip_hdr(skb); - - mtu = ip_skb_dst_mtu(skb); - if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || - (IPCB(skb)->frag_max_size && - IPCB(skb)->frag_max_size > mtu))) { - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); - icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, - htonl(mtu)); - kfree_skb(skb); - return -EMSGSIZE; - } - - /* - * Setup starting values. - */ - hlen = iph->ihl * 4; mtu = mtu - hlen; /* Size of data space */ -#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) - if (skb->nf_bridge) - mtu -= nf_bridge_mtu_reduction(skb); -#endif + IPCB(skb)->flags |= IPSKB_FRAG_COMPLETE; /* When frag_list is given, use it. First, check its validity: @@ -592,10 +560,11 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) ip_send_check(iph); } - err = output(skb); + err = output(skb, output_arg); - if (!err) - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); + if (!err && dev) + IP_INC_STATS(dev_net(dev), + IPSTATS_MIB_FRAGCREATES); if (err || !frag) break; @@ -605,7 +574,8 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) } if (err == 0) { - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); + if (dev) + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); return 0; } @@ -614,7 +584,8 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) kfree_skb(frag); frag = skb; } - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + if (dev) + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); return err; slow_path_clean: @@ -636,10 +607,6 @@ slow_path: left = skb->len - hlen; /* Space per frame */ ptr = hlen; /* Where to start from */ - /* for bridged IP traffic encapsulated inside f.e. a vlan header, - * we need to make room for the encapsulating header - */ - ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); /* * Fragment the datagram. @@ -732,21 +699,67 @@ slow_path: ip_send_check(iph); - err = output(skb2); + err = output(skb2, output_arg); if (err) goto fail; - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); + if (dev) + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGCREATES); } consume_skb(skb); - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); + if (dev) + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGOKS); return err; fail: kfree_skb(skb); - IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + if (dev) + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); return err; } +EXPORT_SYMBOL(ip_fragment_mtu); + +/*This IP datagram is too large to be sent in one piece. Break it up into + *smaller pieces (each of size equal to IP header plus + *a block of the data of the original IP data part) that will yet fit in a + *single device frame, and queue such a frame for sending. + */ +int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) +{ + struct iphdr *iph; + struct net_device *dev; + unsigned int mtu, ll_rs; + struct rtable *rt = skb_rtable(skb); + + dev = rt->dst.dev; + + /* Point into the IP datagram header. */ + iph = ip_hdr(skb); + + mtu = ip_skb_dst_mtu(skb); + if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || + (IPCB(skb)->frag_max_size && + IPCB(skb)->frag_max_size > mtu))) { + IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); + icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, + htonl(mtu)); + kfree_skb(skb); + return -EMSGSIZE; + } + + /* Setup starting values. */ +#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) + if (skb->nf_bridge) + mtu -= nf_bridge_mtu_reduction(skb); +#endif + /* for bridged IP traffic encapsulated inside f.e. a vlan header, + * we need to make room for the encapsulating header + */ + ll_rs = LL_RESERVED_SPACE_EXTRA(rt->dst.dev, nf_bridge_pad(skb)); + + return ip_fragment_mtu(skb, mtu, ll_rs, NULL, dev, + (int (*)(struct sk_buff *, void *output_arg))output); +} EXPORT_SYMBOL(ip_fragment); int -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
