Check the pmtu check at the transport layer (for UDP, ICMP and raw), and
send a local error if socket is PMTUDISC_DO and packet is too big.  This is
actually a pure bugfix for ipv6.  For ipv4, it allows us to do pmtu checks
in the same way as for ipv6.

Signed-off-by: John Heffner <[EMAIL PROTECTED]>
---
 net/ipv4/ip_output.c  |    4 +++-
 net/ipv4/raw.c        |    8 +++++---
 net/ipv6/ip6_output.c |   11 ++++++-----
 net/ipv6/raw.c        |    7 +++++--
 4 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index d096332..593acf7 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -822,7 +822,9 @@ int ip_append_data(struct sock *sk,
        fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
        maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
 
-       if (inet->cork.length + length > 0xFFFF - fragheaderlen) {
+       if (inet->cork.length + length > 0xFFFF - fragheaderlen ||
+           (inet->pmtudisc >= IP_PMTUDISC_DO &&
+            inet->cork.length + length > mtu)) {
                ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, 
mtu-exthdrlen);
                return -EMSGSIZE;
        }
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 87e9c16..f252f4e 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -271,10 +271,12 @@ static int raw_send_hdrinc(struct sock *sk, void *from, 
size_t length,
        struct iphdr *iph;
        struct sk_buff *skb;
        int err;
+       int mtu;
 
-       if (length > rt->u.dst.dev->mtu) {
-               ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport,
-                              rt->u.dst.dev->mtu);
+       mtu = inet->pmtudisc == IP_PMTUDISC_DO ? dst_mtu(&rt->u.dst) :
+                                                rt->u.dst.dev->mtu;
+       if (length > mtu) {
+               ip_local_error(sk, EMSGSIZE, rt->rt_dst, inet->dport, mtu);
                return -EMSGSIZE;
        }
        if (flags&MSG_PROBE)
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 3055169..711dfc3 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1044,11 +1044,12 @@ int ip6_append_data(struct sock *sk, int getfrag(void 
*from, char *to,
        fragheaderlen = sizeof(struct ipv6hdr) + rt->u.dst.nfheader_len + (opt 
? opt->opt_nflen : 0);
        maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen - 
sizeof(struct frag_hdr);
 
-       if (mtu <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN) {
-               if (inet->cork.length + length > sizeof(struct ipv6hdr) + 
IPV6_MAXPLEN - fragheaderlen) {
-                       ipv6_local_error(sk, EMSGSIZE, fl, mtu-exthdrlen);
-                       return -EMSGSIZE;
-               }
+       if ((mtu <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN &&
+            inet->cork.length + length > sizeof(struct ipv6hdr) + IPV6_MAXPLEN 
- fragheaderlen) ||
+           (np->pmtudisc >= IPV6_PMTUDISC_DO &&
+            inet->cork.length + length > mtu)) {
+               ipv6_local_error(sk, EMSGSIZE, fl, mtu-exthdrlen);
+               return -EMSGSIZE;
        }
 
        /*
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 306d5d8..75db277 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -556,9 +556,12 @@ static int rawv6_send_hdrinc(struct sock *sk, void *from, 
int length,
        struct sk_buff *skb;
        unsigned int hh_len;
        int err;
+       int mtu;
 
-       if (length > rt->u.dst.dev->mtu) {
-               ipv6_local_error(sk, EMSGSIZE, fl, rt->u.dst.dev->mtu);
+       mtu = np->pmtudisc == IPV6_PMTUDISC_DO ? dst_mtu(&rt->u.dst) :
+                                                rt->u.dst.dev->mtu;
+       if (length > mtu) {
+               ipv6_local_error(sk, EMSGSIZE, fl, mtu);
                return -EMSGSIZE;
        }
        if (flags&MSG_PROBE)
-- 
1.5.0.2.gc260-dirty

-
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