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Date: Wed, 18 Apr 2007 21:07:44 -0400
From: John Heffner <jheffner@....edu>
To: David Miller <davem@...emloft.net>
Cc: Patrick McHardy <kaber@...sh.net>, netdev@...r.kernel.org,
John Heffner <jheffner@....edu>
Subject: [PATCH] [NET] 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 <jheffner@....edu>
---
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 1912e7c..3975cbf 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 4e8350a..d559fac 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 34606ef..66e2c3a 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 c199d23..4d54457 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 5a5b7d4..f508171 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 da930fa..aa3d07c 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;
--
1.5.1.rc3.30.ga8f4-dirty
-
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