diff options
| -rw-r--r-- | include/net/inet_frag.h | 2 | ||||
| -rw-r--r-- | include/net/ip.h | 1 | ||||
| -rw-r--r-- | net/ipv4/ip_fragment.c | 31 | ||||
| -rw-r--r-- | net/ipv4/ip_output.c | 12 |
4 files changed, 38 insertions, 8 deletions
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index 8d1765577acc..e1300b3dd597 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -43,7 +43,7 @@ enum { * @len: total length of the original datagram * @meat: length of received fragments so far * @flags: fragment queue flags - * @max_size: (ipv4 only) maximum received fragment size with IP_DF set + * @max_size: maximum received fragment size * @net: namespace that this frag belongs to */ struct inet_frag_queue { diff --git a/include/net/ip.h b/include/net/ip.h index 7921a36b805c..9b976cf99122 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -45,6 +45,7 @@ struct inet_skb_parm { #define IPSKB_FRAG_COMPLETE BIT(3) #define IPSKB_REROUTED BIT(4) #define IPSKB_DOREDIRECT BIT(5) +#define IPSKB_FRAG_PMTU BIT(6) u16 frag_max_size; }; diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index 47fa64ee82b1..a50dc6d408d1 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -75,6 +75,7 @@ struct ipq { __be16 id; u8 protocol; u8 ecn; /* RFC3168 support */ + u16 max_df_size; /* largest frag with DF set seen */ int iif; unsigned int rid; struct inet_peer *peer; @@ -326,6 +327,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) { struct sk_buff *prev, *next; struct net_device *dev; + unsigned int fragsize; int flags, offset; int ihl, end; int err = -ENOENT; @@ -481,9 +483,14 @@ found: if (offset == 0) qp->q.flags |= INET_FRAG_FIRST_IN; + fragsize = skb->len + ihl; + + if (fragsize > qp->q.max_size) + qp->q.max_size = fragsize; + if (ip_hdr(skb)->frag_off & htons(IP_DF) && - skb->len + ihl > qp->q.max_size) - qp->q.max_size = skb->len + ihl; + fragsize > qp->max_df_size) + qp->max_df_size = fragsize; if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && qp->q.meat == qp->q.len) { @@ -613,13 +620,27 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, head->next = NULL; head->dev = dev; head->tstamp = qp->q.stamp; - IPCB(head)->frag_max_size = qp->q.max_size; + IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size); iph = ip_hdr(head); - /* max_size != 0 implies at least one fragment had IP_DF set */ - iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0; iph->tot_len = htons(len); iph->tos |= ecn; + + /* When we set IP_DF on a refragmented skb we must also force a + * call to ip_fragment to avoid forwarding a DF-skb of size s while + * original sender only sent fragments of size f (where f < s). + * + * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest + * frag seen to avoid sending tiny DF-fragments in case skb was built + * from one very small df-fragment and one large non-df frag. + */ + if (qp->max_df_size == qp->q.max_size) { + IPCB(head)->flags |= IPSKB_FRAG_PMTU; + iph->frag_off = htons(IP_DF); + } else { + iph->frag_off = 0; + } + IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); qp->q.fragments = NULL; qp->q.fragments_tail = NULL; diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index d6dd8ba04441..f5f5ef1cebd5 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -278,7 +278,7 @@ static int ip_finish_output(struct sock *sk, struct sk_buff *skb) if (skb_is_gso(skb)) return ip_finish_output_gso(sk, skb, mtu); - if (skb->len > mtu) + if (skb->len > mtu || (IPCB(skb)->flags & IPSKB_FRAG_PMTU)) return ip_fragment(sk, skb, mtu, ip_finish_output2); return ip_finish_output2(sk, skb); @@ -492,7 +492,10 @@ static int ip_fragment(struct sock *sk, struct sk_buff *skb, { struct iphdr *iph = ip_hdr(skb); - if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || + if ((iph->frag_off & htons(IP_DF)) == 0) + return ip_do_fragment(sk, skb, output); + + if (unlikely(!skb->ignore_df || (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size > mtu))) { struct rtable *rt = skb_rtable(skb); @@ -537,6 +540,8 @@ int ip_do_fragment(struct sock *sk, struct sk_buff *skb, iph = ip_hdr(skb); mtu = ip_skb_dst_mtu(skb); + if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu) + mtu = IPCB(skb)->frag_max_size; /* * Setup starting values. @@ -732,6 +737,9 @@ slow_path: iph = ip_hdr(skb2); iph->frag_off = htons((offset >> 3)); + if (IPCB(skb)->flags & IPSKB_FRAG_PMTU) + iph->frag_off |= htons(IP_DF); + /* ANK: dirty, but effective trick. Upgrade options only if * the segment to be fragmented was THE FIRST (otherwise, * options are already fixed) and make it ONCE |