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ipv6: support IPV6_PMTU_INTERFACE on sockets
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IPV6_PMTU_INTERFACE is the same as IPV6_PMTU_PROBE for ipv6. Add it
nontheless for symmetry with IPv4 sockets. Also drop incoming MTU
information if this mode is enabled.

The additional bit in ipv6_pinfo just eats in the padding behind the
bitfield. There are no changes to the layout of the struct at all.

Signed-off-by: Hannes Frederic Sowa <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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strssndktn authored and davem330 committed Dec 18, 2013
1 parent cd174e6 commit 93b36cf
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Showing 9 changed files with 28 additions and 7 deletions.
2 changes: 1 addition & 1 deletion include/linux/ipv6.h
Original file line number Diff line number Diff line change
Expand Up @@ -191,7 +191,7 @@ struct ipv6_pinfo {
/* sockopt flags */
__u16 recverr:1,
sndflow:1,
pmtudisc:2,
pmtudisc:3,
ipv6only:1,
srcprefs:3, /* 001: prefer temporary address
* 010: prefer public address
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7 changes: 6 additions & 1 deletion include/net/ip6_route.h
Original file line number Diff line number Diff line change
Expand Up @@ -178,10 +178,15 @@ 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) ?
return (np && np->pmtudisc >= IPV6_PMTUDISC_PROBE) ?
skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
}

static inline bool ip6_sk_accept_pmtu(const struct sock *sk)
{
return inet6_sk(sk)->pmtudisc != IPV6_PMTUDISC_INTERFACE;
}

static inline struct in6_addr *rt6_nexthop(struct rt6_info *rt)
{
return &rt->rt6i_gateway;
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4 changes: 4 additions & 0 deletions include/uapi/linux/in6.h
Original file line number Diff line number Diff line change
Expand Up @@ -188,6 +188,10 @@ enum {
#define IPV6_PMTUDISC_WANT 1
#define IPV6_PMTUDISC_DO 2
#define IPV6_PMTUDISC_PROBE 3
/* same as IPV6_PMTUDISC_PROBE, provided for symetry with IPv4
* also see comments on IP_PMTUDISC_INTERFACE
*/
#define IPV6_PMTUDISC_INTERFACE 4

/* Flowlabel */
#define IPV6_FLOWLABEL_MGR 32
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3 changes: 3 additions & 0 deletions net/dccp/ipv6.c
Original file line number Diff line number Diff line change
Expand Up @@ -141,6 +141,9 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
if (type == ICMPV6_PKT_TOOBIG) {
struct dst_entry *dst = NULL;

if (!ip6_sk_accept_pmtu(sk))
goto out;

if (sock_owned_by_user(sk))
goto out;
if ((1 << sk->sk_state) & (DCCPF_LISTEN | DCCPF_CLOSED))
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6 changes: 3 additions & 3 deletions net/ipv6/ip6_output.c
Original file line number Diff line number Diff line change
Expand Up @@ -1165,10 +1165,10 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
np->cork.hop_limit = hlimit;
np->cork.tclass = tclass;
if (rt->dst.flags & DST_XFRM_TUNNEL)
mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
rt->dst.dev->mtu : dst_mtu(&rt->dst);
else
mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
rt->dst.dev->mtu : dst_mtu(rt->dst.path);
if (np->frag_size < mtu) {
if (np->frag_size)
Expand Down Expand Up @@ -1270,7 +1270,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
if (skb == NULL || skb_prev == NULL)
ip6_append_data_mtu(&mtu, &maxfraglen,
fragheaderlen, skb, rt,
np->pmtudisc ==
np->pmtudisc >=
IPV6_PMTUDISC_PROBE);

skb_prev = skb;
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2 changes: 1 addition & 1 deletion net/ipv6/ipv6_sockglue.c
Original file line number Diff line number Diff line change
Expand Up @@ -722,7 +722,7 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
case IPV6_MTU_DISCOVER:
if (optlen < sizeof(int))
goto e_inval;
if (val < IP_PMTUDISC_DONT || val > IP_PMTUDISC_PROBE)
if (val < IPV6_PMTUDISC_DONT || val > IPV6_PMTUDISC_INTERFACE)
goto e_inval;
np->pmtudisc = val;
retv = 0;
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3 changes: 3 additions & 0 deletions net/ipv6/tcp_ipv6.c
Original file line number Diff line number Diff line change
Expand Up @@ -397,6 +397,9 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
if (sk->sk_state == TCP_LISTEN)
goto out;

if (!ip6_sk_accept_pmtu(sk))
goto out;

tp->mtu_info = ntohl(info);
if (!sock_owned_by_user(sk))
tcp_v6_mtu_reduced(sk);
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5 changes: 4 additions & 1 deletion net/ipv6/udp.c
Original file line number Diff line number Diff line change
Expand Up @@ -538,8 +538,11 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
if (sk == NULL)
return;

if (type == ICMPV6_PKT_TOOBIG)
if (type == ICMPV6_PKT_TOOBIG) {
if (!ip6_sk_accept_pmtu(sk))
goto out;
ip6_sk_update_pmtu(skb, sk, info);
}
if (type == NDISC_REDIRECT) {
ip6_sk_redirect(skb, sk);
goto out;
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3 changes: 3 additions & 0 deletions net/sctp/input.c
Original file line number Diff line number Diff line change
Expand Up @@ -389,6 +389,9 @@ void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
if (!t || (t->pathmtu <= pmtu))
return;

if (!ip6_sk_accept_pmtu(sk))
return;

if (sock_owned_by_user(sk)) {
asoc->pmtu_pending = 1;
t->pmtu_pending = 1;
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