[PATCH net-next 2/3] ipv6: add IPV6_RECVFRAGSIZE cmsg
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2016-11-02 15:02:28
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
From: Willem de Bruijn <willemb@google.com> When reading a datagram or raw packet that arrived fragmented, expose the maximum fragment size if recorded to allow applications to estimate receive path MTU. At this point, the field is only recorded when ipv6 connection tracking is enabled. A follow-up patch will record this field also in the ipv6 input path. Tested using the test for IP_RECVFRAGSIZE plus ip netns exec to ip addr add dev veth1 fc07::1/64 ip netns exec from ip addr add dev veth0 fc07::2/64 ip netns exec to ./recv_cmsg_recvfragsize -6 -u -p 6000 & ip netns exec from nc -q 1 -u fc07::1 6000 < payload Both with and without enabling connection tracking ip6tables -A INPUT -m state --state NEW -p udp -j LOG Signed-off-by: Willem de Bruijn <willemb@google.com> --- include/linux/ipv6.h | 5 +++-- include/uapi/linux/in6.h | 1 + net/ipv6/datagram.c | 5 +++++ net/ipv6/ipv6_sockglue.c | 8 ++++++++ 4 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index ca1ad9e..1afb6e8 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h@@ -229,8 +229,9 @@ struct ipv6_pinfo { rxflow:1, rxtclass:1, rxpmtu:1, - rxorigdstaddr:1; - /* 2 bits hole */ + rxorigdstaddr:1, + recvfragsize:1; + /* 1 bits hole */ } bits; __u16 all; } rxopt;
diff --git a/include/uapi/linux/in6.h b/include/uapi/linux/in6.h
index b39ea4f..46444f8 100644
--- a/include/uapi/linux/in6.h
+++ b/include/uapi/linux/in6.h@@ -283,6 +283,7 @@ struct in6_flowlabel_req { #define IPV6_RECVORIGDSTADDR IPV6_ORIGDSTADDR #define IPV6_TRANSPARENT 75 #define IPV6_UNICAST_IF 76 +#define IPV6_RECVFRAGSIZE 77 /* * Multicast Routing:
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 37874e2..620c79a 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c@@ -715,6 +715,11 @@ void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg, put_cmsg(msg, SOL_IPV6, IPV6_ORIGDSTADDR, sizeof(sin6), &sin6); } } + if (np->rxopt.bits.recvfragsize && opt->frag_max_size) { + int val = opt->frag_max_size; + + put_cmsg(msg, SOL_IPV6, IPV6_RECVFRAGSIZE, sizeof(val), &val); + } } void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 636ec56..6c12678 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c@@ -868,6 +868,10 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname, np->autoflowlabel = valbool; retv = 0; break; + case IPV6_RECVFRAGSIZE: + np->rxopt.bits.recvfragsize = valbool; + retv = 0; + break; } release_sock(sk);
@@ -1310,6 +1314,10 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname, val = np->autoflowlabel; break; + case IPV6_RECVFRAGSIZE: + val = np->rxopt.bits.recvfragsize; + break; + default: return -ENOPROTOOPT; }
--
2.8.0.rc3.226.g39d4020