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Commit 0b95227a authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by David S. Miller
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ipv6: yet another new IPV6_MTU_DISCOVER option IPV6_PMTUDISC_OMIT 



This option has the same semantic as IP_PMTUDISC_OMIT for IPv4 which
got recently introduced. It doesn't honor the path mtu discovered by the
host but in contrary to IPV6_PMTUDISC_INTERFACE allows the generation of
fragments if the packet size exceeds the MTU of the outgoing interface
MTU.

Fixes: 93b36cf3 ("ipv6: support IPV6_PMTU_INTERFACE on sockets")
Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1b346576

include/net/ip6_route.h

+8 −1
Original line number Diff line number Diff line
@@ -171,7 +171,14 @@ static inline int ip6_skb_dst_mtu(struct sk_buff *skb) 


static inline bool ip6_sk_accept_pmtu(const struct sock *sk)

{

	return inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_INTERFACE;

	return inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_INTERFACE &&

	       inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_OMIT;

}



static inline bool ip6_sk_local_df(const struct sock *sk)

{

	return inet6_sk(sk)->pmtudisc < IPV6_PMTUDISC_DO ||

	       inet6_sk(sk)->pmtudisc == IPV6_PMTUDISC_OMIT;

}



static inline struct in6_addr *rt6_nexthop(struct rt6_info *rt)

include/uapi/linux/in6.h

+4 −0
Original line number Diff line number Diff line
@@ -185,6 +185,10 @@ struct in6_flowlabel_req { 
 * also see comments on IP_PMTUDISC_INTERFACE

 */

#define IPV6_PMTUDISC_INTERFACE		4

/* weaker version of IPV6_PMTUDISC_INTERFACE, which allows packets to

 * get fragmented if they exceed the interface mtu

 */

#define IPV6_PMTUDISC_OMIT		5



/* Flowlabel */

#define IPV6_FLOWLABEL_MGR	32

net/ipv6/ip6_output.c

+5 −4
Original line number Diff line number Diff line
@@ -1234,8 +1234,10 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to, 
			      sizeof(struct frag_hdr) : 0) +

			     rt->rt6i_nfheader_len;



		maxnonfragsize = (np->pmtudisc >= IPV6_PMTUDISC_DO) ?

				 mtu : sizeof(struct ipv6hdr) + IPV6_MAXPLEN;

		if (ip6_sk_local_df(sk))

			maxnonfragsize = sizeof(struct ipv6hdr) + IPV6_MAXPLEN;

		else

			maxnonfragsize = mtu;



		/* dontfrag active */

		if ((cork->length + length > mtu - headersize) && dontfrag &&
@@ -1543,8 +1545,7 @@ int ip6_push_pending_frames(struct sock *sk) 
	}



	/* Allow local fragmentation. */

	if (np->pmtudisc < IPV6_PMTUDISC_DO)

		skb->local_df = 1;

	skb->local_df = ip6_sk_local_df(sk);



	*final_dst = fl6->daddr;

	__skb_pull(skb, skb_network_header_len(skb));

net/ipv6/ipv6_sockglue.c

+1 −1
Original line number Diff line number Diff line
@@ -722,7 +722,7 @@ done: 
	case IPV6_MTU_DISCOVER:

		if (optlen < sizeof(int))

			goto e_inval;

		if (val < IPV6_PMTUDISC_DONT || val > IPV6_PMTUDISC_INTERFACE)

		if (val < IPV6_PMTUDISC_DONT || val > IPV6_PMTUDISC_OMIT)

			goto e_inval;

		np->pmtudisc = val;

		retv = 0;