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Commit 628a5c56 authored by John Heffner's avatar John Heffner Committed by David S. Miller
Browse files

[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: default avatarJohn Heffner <jheffner@psc.edu>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b881ef76

include/linux/in.h

+1 −0
Original line number Diff line number Diff line
@@ -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

include/linux/in6.h

+1 −0
Original line number Diff line number Diff line
@@ -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

net/ipv4/ip_output.c

+15 −5
Original line number Diff line number Diff line
@@ -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);

net/ipv4/ip_sockglue.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/ipv6/ip6_output.c

+12 −3
Original line number Diff line number Diff line
@@ -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;