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authorHannes Frederic Sowa <hannes@stressinduktion.org>2014-02-26 01:20:42 +0100
committerDavid S. Miller <davem@davemloft.net>2014-02-26 15:51:00 -0500
commit1b346576359c72bee34b1476b4fc63d77d37b314 (patch)
treec39719e520d1771322b8e9e801c873587e05d237 /net/ipv4
parent69647ce46a236a355a7a3096d793819a9bd7c1d3 (diff)
ipv4: yet another new IP_MTU_DISCOVER option IP_PMTUDISC_OMIT
IP_PMTUDISC_INTERFACE has a design error: because it does not allow the generation of fragments if the interface mtu is exceeded, it is very hard to make use of this option in already deployed name server software for which I introduced this option. This patch adds yet another new IP_MTU_DISCOVER option to not honor any path mtu information and not accepting new icmp notifications destined for the socket this option is enabled on. But we allow outgoing fragmentation in case the packet size exceeds the outgoing interface mtu. As such this new option can be used as a drop-in replacement for IP_PMTUDISC_DONT, which is currently in use by most name server software making the adoption of this option very smooth and easy. The original advantage of IP_PMTUDISC_INTERFACE is still maintained: ignoring incoming path MTU updates and not honoring discovered path MTUs in the output path. Fixes: 482fc6094afad5 ("ipv4: introduce new IP_MTU_DISCOVER mode IP_PMTUDISC_INTERFACE") Cc: Florian Weimer <fweimer@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ip_output.c9
-rw-r--r--net/ipv4/ip_sockglue.c2
2 files changed, 4 insertions, 7 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 22aa11971ed..e85445b2b10 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -824,8 +824,7 @@ static int __ip_append_data(struct sock *sk,
fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
- maxnonfragsize = (inet->pmtudisc >= IP_PMTUDISC_DO) ?
- mtu : 0xFFFF;
+ maxnonfragsize = ip_sk_local_df(sk) ? 0xFFFF : mtu;
if (cork->length + length > maxnonfragsize - fragheaderlen) {
ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
@@ -1148,8 +1147,7 @@ ssize_t ip_append_page(struct sock *sk, struct flowi4 *fl4, struct page *page,
fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0);
maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen;
- maxnonfragsize = (inet->pmtudisc >= IP_PMTUDISC_DO) ?
- mtu : 0xFFFF;
+ maxnonfragsize = ip_sk_local_df(sk) ? 0xFFFF : mtu;
if (cork->length + size > maxnonfragsize - fragheaderlen) {
ip_local_error(sk, EMSGSIZE, fl4->daddr, inet->inet_dport,
@@ -1310,8 +1308,7 @@ struct sk_buff *__ip_make_skb(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)
- skb->local_df = 1;
+ skb->local_df = ip_sk_local_df(sk);
/* 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
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 0968b28c4cf..64741b93863 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -643,7 +643,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
inet->nodefrag = val ? 1 : 0;
break;
case IP_MTU_DISCOVER:
- if (val < IP_PMTUDISC_DONT || val > IP_PMTUDISC_INTERFACE)
+ if (val < IP_PMTUDISC_DONT || val > IP_PMTUDISC_OMIT)
goto e_inval;
inet->pmtudisc = val;
break;