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Date: Fri, 23 Mar 2007 20:06:46 -0400
From: John Heffner <jheffner@....edu>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, John Heffner <jheffner@....edu>
Subject: [PATCH 3/3] [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 +
include/linux/skbuff.h | 3 ++-
include/net/ip.h | 2 +-
net/core/skbuff.c | 2 ++
net/ipv4/ip_output.c | 14 ++++++++++----
net/ipv4/ip_sockglue.c | 2 +-
net/ipv4/raw.c | 3 +++
net/ipv6/ip6_output.c | 12 ++++++++----
net/ipv6/ipv6_sockglue.c | 2 +-
net/ipv6/raw.c | 3 +++
11 files changed, 33 insertions(+), 12 deletions(-)
diff --git a/include/linux/in.h b/include/linux/in.h
index 1912e7c..2dc1f8a 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/include/linux/skbuff.h b/include/linux/skbuff.h
index 4ff3940..64038b4 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -284,7 +284,8 @@ struct sk_buff {
nfctinfo:3;
__u8 pkt_type:3,
fclone:2,
- ipvs_property:1;
+ ipvs_property:1,
+ ign_dst_mtu;
__be16 protocol;
void (*destructor)(struct sk_buff *skb);
diff --git a/include/net/ip.h b/include/net/ip.h
index e79c3e3..f5874a3 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -201,7 +201,7 @@ int ip_decrease_ttl(struct iphdr *iph)
static inline
int ip_dont_fragment(struct sock *sk, struct dst_entry *dst)
{
- return (inet_sk(sk)->pmtudisc == IP_PMTUDISC_DO ||
+ return (inet_sk(sk)->pmtudisc >= IP_PMTUDISC_DO ||
(inet_sk(sk)->pmtudisc == IP_PMTUDISC_WANT &&
!(dst_metric(dst, RTAX_LOCK)&(1<<RTAX_MTU))));
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 702fa8f..5c8515c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -474,6 +474,7 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
C(ipvs_property);
#endif
+ C(ign_dst_mtu);
C(protocol);
n->destructor = NULL;
C(mark);
@@ -549,6 +550,7 @@ static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
#if defined(CONFIG_IP_VS) || defined(CONFIG_IP_VS_MODULE)
new->ipvs_property = old->ipvs_property;
#endif
+ new->ign_dst_mtu = old->ign_dst_mtu;
#ifdef CONFIG_BRIDGE_NETFILTER
new->nf_bridge = old->nf_bridge;
nf_bridge_get(old->nf_bridge);
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 90bdd53..a7e8944 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -201,7 +201,8 @@ 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 > dst_mtu(skb->dst) &&
+ !skb->ign_dst_mtu && !skb_is_gso(skb))
return ip_fragment(skb, ip_finish_output2);
else
return ip_finish_output2(skb);
@@ -801,7 +802,9 @@ 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;
@@ -1220,13 +1223,16 @@ 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;
+ if (inet->pmtudisc == IP_PMTUDISC_PROBE)
+ skb->ign_dst_mtu = 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 23048d9..98fa088 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -536,7 +536,7 @@ 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/ipv4/raw.c b/net/ipv4/raw.c
index f252f4e..f562262 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -302,6 +302,9 @@ static int raw_send_hdrinc(struct sock *sk, void *from, size_t length,
if (err)
goto error_fault;
+ if (inet->pmtudisc == IP_PMTUDISC_PROBE)
+ skb->ign_dst_mtu = 1;
+
/* We don't modify invalid header */
if (length >= sizeof(*iph) && iph->ihl * 4U <= length) {
if (!iph->saddr)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 711dfc3..8b8c04b 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -139,8 +139,8 @@ static int ip6_output2(struct sk_buff *skb)
int ip6_output(struct sk_buff *skb)
{
- if ((skb->len > dst_mtu(skb->dst) && !skb_is_gso(skb)) ||
- dst_allfrag(skb->dst))
+ if ((skb->len > dst_mtu(skb->dst) && !skb->ign_dst_mtu &&
+ !skb_is_gso(skb)) || dst_allfrag(skb->dst))
return ip6_fragment(skb, ip6_output2);
else
return ip6_output2(skb);
@@ -574,7 +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 = skb->ign_dst_mtu ? skb->len : dst_mtu(&rt->u.dst);
if (np && np->frag_size < mtu) {
if (np->frag_size)
mtu = np->frag_size;
@@ -1015,7 +1015,8 @@ 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;
@@ -1303,6 +1304,9 @@ int ip6_push_pending_frames(struct sock *sk)
tmp_skb->sk = NULL;
}
+ if (np->pmtudisc == IPV6_PMTUDISC_PROBE)
+ skb->ign_dst_mtu = 1;
+
ipv6_addr_copy(final_dst, &fl->fl6_dst);
__skb_pull(skb, skb->h.raw - skb->nh.raw);
if (opt && opt->opt_flen)
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index f5f9582..6e88597 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;
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 75db277..9ef0946 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -587,6 +587,9 @@ static int rawv6_send_hdrinc(struct sock *sk, void *from, int length,
if (err)
goto error_fault;
+ if (np->pmtudisc == IPV6_PMTUDISC_PROBE)
+ skb->ign_dst_mtu = 1;
+
IP6_INC_STATS(rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
dst_output);
--
1.5.0.2.gc260-dirty
-
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