From 628a5c561890a9a9a74dea017873530584aab06e Mon Sep 17 00:00:00 2001 From: John Heffner Date: Fri, 20 Apr 2007 15:53:27 -0700 Subject: [PATCH] [INET]: Add IP(V6)_PMTUDISC_RPOBE Add IP(V6)_PMTUDISC_PROBE value for IP(V6)_MTU_DISCOVER. This option forces us not to fragment, but does not make use of the kernel path MTU discovery. That is, it allows for user-mode MTU probing (or, packetization-layer path MTU discovery). This is particularly useful for diagnostic utilities, like traceroute/tracepath. Signed-off-by: John Heffner Signed-off-by: David S. Miller --- include/linux/in.h | 1 + include/linux/in6.h | 1 + net/ipv4/ip_output.c | 20 +++++++++++++++----- net/ipv4/ip_sockglue.c | 2 +- net/ipv6/ip6_output.c | 15 ++++++++++++--- net/ipv6/ipv6_sockglue.c | 2 +- 6 files changed, 31 insertions(+), 10 deletions(-) diff --git a/include/linux/in.h b/include/linux/in.h index 1912e7c0bc26..3975cbf52f20 100644 --- a/include/linux/in.h +++ b/include/linux/in.h @@ -83,6 +83,7 @@ struct in_addr { #define IP_PMTUDISC_DONT 0 /* Never send DF frames */ #define IP_PMTUDISC_WANT 1 /* Use per route hints */ #define IP_PMTUDISC_DO 2 /* Always DF */ +#define IP_PMTUDISC_PROBE 3 /* Ignore dst pmtu */ #define IP_MULTICAST_IF 32 #define IP_MULTICAST_TTL 33 diff --git a/include/linux/in6.h b/include/linux/in6.h index 4e8350ae8869..d559fac4a26d 100644 --- a/include/linux/in6.h +++ b/include/linux/in6.h @@ -179,6 +179,7 @@ struct in6_flowlabel_req #define IPV6_PMTUDISC_DONT 0 #define IPV6_PMTUDISC_WANT 1 #define IPV6_PMTUDISC_DO 2 +#define IPV6_PMTUDISC_PROBE 3 /* Flowlabel */ #define IPV6_FLOWLABEL_MGR 32 diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 34606eff8a05..534650cad3a8 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -189,6 +189,14 @@ static inline int ip_finish_output2(struct sk_buff *skb) return -EINVAL; } +static inline int ip_skb_dst_mtu(struct sk_buff *skb) +{ + struct inet_sock *inet = skb->sk ? inet_sk(skb->sk) : NULL; + + return (inet && inet->pmtudisc == IP_PMTUDISC_PROBE) ? + skb->dst->dev->mtu : dst_mtu(skb->dst); +} + static inline int ip_finish_output(struct sk_buff *skb) { #if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM) @@ -198,7 +206,7 @@ static inline int ip_finish_output(struct sk_buff *skb) return dst_output(skb); } #endif - if (skb->len > dst_mtu(skb->dst) && !skb_is_gso(skb)) + if (skb->len > ip_skb_dst_mtu(skb) && !skb_is_gso(skb)) return ip_fragment(skb, ip_finish_output2); else return ip_finish_output2(skb); @@ -422,7 +430,7 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff*)) if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { IP_INC_STATS(IPSTATS_MIB_FRAGFAILS); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, - htonl(dst_mtu(&rt->u.dst))); + htonl(ip_skb_dst_mtu(skb))); kfree_skb(skb); return -EMSGSIZE; } @@ -787,7 +795,9 @@ int ip_append_data(struct sock *sk, inet->cork.addr = ipc->addr; } dst_hold(&rt->u.dst); - inet->cork.fragsize = mtu = dst_mtu(rt->u.dst.path); + inet->cork.fragsize = mtu = inet->pmtudisc == IP_PMTUDISC_PROBE ? + rt->u.dst.dev->mtu : + dst_mtu(rt->u.dst.path); inet->cork.rt = rt; inet->cork.length = 0; sk->sk_sndmsg_page = NULL; @@ -1203,13 +1213,13 @@ int ip_push_pending_frames(struct sock *sk) * to fragment the frame generated here. No matter, what transforms * how transforms change size of the packet, it will come out. */ - if (inet->pmtudisc != IP_PMTUDISC_DO) + if (inet->pmtudisc < IP_PMTUDISC_DO) skb->local_df = 1; /* DF bit is set when we want to see DF on outgoing frames. * If local_df is set too, we still allow to fragment this frame * locally. */ - if (inet->pmtudisc == IP_PMTUDISC_DO || + if (inet->pmtudisc >= IP_PMTUDISC_DO || (skb->len <= dst_mtu(&rt->u.dst) && ip_dont_fragment(sk, &rt->u.dst))) df = htons(IP_DF); diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index c199d2311731..4d544573f48a 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -542,7 +542,7 @@ static int do_ip_setsockopt(struct sock *sk, int level, inet->hdrincl = val ? 1 : 0; break; case IP_MTU_DISCOVER: - if (val<0 || val>2) + if (val<0 || val>3) goto e_inval; inet->pmtudisc = val; break; diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 5a5b7d4ad31c..f508171bab73 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -137,9 +137,17 @@ static int ip6_output2(struct sk_buff *skb) return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb,NULL, skb->dev,ip6_output_finish); } +static inline int ip6_skb_dst_mtu(struct sk_buff *skb) +{ + struct ipv6_pinfo *np = skb->sk ? inet6_sk(skb->sk) : NULL; + + return (np && np->pmtudisc == IPV6_PMTUDISC_PROBE) ? + skb->dst->dev->mtu : dst_mtu(skb->dst); +} + int ip6_output(struct sk_buff *skb) { - if ((skb->len > dst_mtu(skb->dst) && !skb_is_gso(skb)) || + if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) || dst_allfrag(skb->dst)) return ip6_fragment(skb, ip6_output2); else @@ -566,7 +574,7 @@ static int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) hlen = ip6_find_1stfragopt(skb, &prevhdr); nexthdr = *prevhdr; - mtu = dst_mtu(&rt->u.dst); + mtu = ip6_skb_dst_mtu(skb); /* We must not fragment if the socket is set to force MTU discovery * or if the skb it not generated by a local socket. (This last @@ -1063,7 +1071,8 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to, inet->cork.fl = *fl; np->cork.hop_limit = hlimit; np->cork.tclass = tclass; - mtu = dst_mtu(rt->u.dst.path); + mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ? + rt->u.dst.dev->mtu : dst_mtu(rt->u.dst.path); if (np->frag_size < mtu) { if (np->frag_size) mtu = np->frag_size; diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c index da930fa089c9..aa3d07c52a8f 100644 --- a/net/ipv6/ipv6_sockglue.c +++ b/net/ipv6/ipv6_sockglue.c @@ -694,7 +694,7 @@ done: retv = ip6_ra_control(sk, val, NULL); break; case IPV6_MTU_DISCOVER: - if (val<0 || val>2) + if (val<0 || val>3) goto e_inval; np->pmtudisc = val; retv = 0;