diff options
| author |   Hannes Frederic Sowa <hannes@stressinduktion.org> | 2014-02-26 01:20:42 +0100 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2014-02-26 15:51:00 -0500 |
| commit | 1b346576359c72bee34b1476b4fc63d77d37b314 (patch) | |
| tree | c39719e520d1771322b8e9e801c873587e05d237 /include | |
| parent | ipv4: use ip_skb_dst_mtu to determine mtu in ip_fragment (diff) | |
| download | linux-dev-1b346576359c72bee34b1476b4fc63d77d37b314.tar.xz linux-dev-1b346576359c72bee34b1476b4fc63d77d37b314.zip | |
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 'include')
| -rw-r--r-- | include/net/ip.h | 9 | ||||
| -rw-r--r-- | include/uapi/linux/in.h | 4 |
2 files changed, 12 insertions, 1 deletions
diff --git a/include/net/ip.h b/include/net/ip.h index 4aa781b7f609..b885d75cede4 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -266,7 +266,8 @@ int ip_dont_fragment(struct sock *sk, struct dst_entry *dst) static inline bool ip_sk_accept_pmtu(const struct sock *sk) { - return inet_sk(sk)->pmtudisc != IP_PMTUDISC_INTERFACE; + return inet_sk(sk)->pmtudisc != IP_PMTUDISC_INTERFACE && + inet_sk(sk)->pmtudisc != IP_PMTUDISC_OMIT; } static inline bool ip_sk_use_pmtu(const struct sock *sk) @@ -274,6 +275,12 @@ static inline bool ip_sk_use_pmtu(const struct sock *sk) return inet_sk(sk)->pmtudisc < IP_PMTUDISC_PROBE; } +static inline bool ip_sk_local_df(const struct sock *sk) +{ + return inet_sk(sk)->pmtudisc < IP_PMTUDISC_DO || + inet_sk(sk)->pmtudisc == IP_PMTUDISC_OMIT; +} + static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, bool forwarding) { diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h index 393c5de09d42..c33a65e3d62c 100644 --- a/include/uapi/linux/in.h +++ b/include/uapi/linux/in.h @@ -120,6 +120,10 @@ struct in_addr { * this socket to prevent accepting spoofed ones. */ #define IP_PMTUDISC_INTERFACE 4 +/* weaker version of IP_PMTUDISC_INTERFACE, which allos packets to get + * fragmented if they exeed the interface mtu + */ +#define IP_PMTUDISC_OMIT 5 #define IP_MULTICAST_IF 32 #define IP_MULTICAST_TTL 33 |