diff options
Diffstat (limited to 'include/net/ip6_route.h')
| -rw-r--r-- | include/net/ip6_route.h | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index 7c5512baa4b2..bcbd5eb1a078 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -266,6 +266,12 @@ static inline bool ipv6_anycast_destination(const struct dst_entry *dst, int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, int (*output)(struct net *, struct sock *, struct sk_buff *)); +/* Variant of dst_mtu() for IPv6 users */ +static inline u32 dst6_mtu(const struct dst_entry *dst) +{ + return INDIRECT_CALL_1(dst->ops->mtu, ip6_mtu, dst); +} + static inline unsigned int ip6_skb_dst_mtu(const struct sk_buff *skb) { const struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ? @@ -346,6 +352,43 @@ out: return mtu - lwtunnel_headroom(dst->lwtstate, mtu); } +/* Configured/administrative MTU of a route, for advertising the TCP MSS. + * + * Unlike ip6_dst_mtu_maybe_forward(), this ignores any ICMPv6-learned path + * MTU (which is kept on the RTF_CACHE exception route) and returns the MTU of + * the underlying route (fib6_pmtu) or the egress device. The advertised MSS + * bounds what the peer may send to us and must reflect our receive + * capability, not a path MTU learned on the reverse (send) direction. See + * RFC 2923 section 2.3 and the comment above tcp_advertise_mss(). + */ +static inline unsigned int ip6_dst_mtu_configured(const struct dst_entry *dst) +{ + const struct rt6_info *rt = dst_rt6_info(dst); + const struct fib6_info *from; + struct inet6_dev *idev; + unsigned int mtu = 0; + + rcu_read_lock(); + /* IPv6 keeps the learned PMTU and the configured MTU in the same + * RTAX_MTU slot: the learned value sits on this (possibly RTF_CACHE) + * dst, the configured one on the underlying route. Reach the latter + * via ->from (fib6_pmtu), populated by ip6_route_info_create(). + */ + from = rcu_dereference(rt->from); + if (from) + mtu = from->fib6_pmtu; + if (!mtu) { + mtu = IPV6_MIN_MTU; + idev = __in6_dev_get(dst_dev_rcu(dst)); + if (idev) + mtu = max_t(unsigned int, mtu, READ_ONCE(idev->cnf.mtu6)); + } + rcu_read_unlock(); + + mtu = min_t(unsigned int, mtu, IP6_MAX_MTU); + return mtu - lwtunnel_headroom(dst->lwtstate, mtu); +} + u32 ip6_mtu_from_fib6(const struct fib6_result *res, const struct in6_addr *daddr, const struct in6_addr *saddr); |