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Message-Id: <1328651073-976-1-git-send-email-ehoover@mines.edu>
Date: Tue, 7 Feb 2012 14:44:32 -0700
From: "Erich E. Hoover" <ehoover@...es.edu>
To: Linux Netdev <netdev@...r.kernel.org>
Cc: "Erich E. Hoover" <ehoover@...es.edu>
Subject: [PATCH v6 1/2] Implement IP_UNICAST_IF socket option.
The IP_UNICAST_IF feature is needed by the Wine project. This patch implements the feature by setting the outgoing interface in a similar fashion to that of IP_MULTICAST_IF. A separate option is needed to handle this feature since the existing options do not provide all of the characteristics required by IP_UNICAST_IF, a summary is provided below.
SO_BINDTODEVICE:
* SO_BINDTODEVICE requires administrative privileges, IP_UNICAST_IF does not. From reading some old mailing list articles my understanding is that SO_BINDTODEVICE requires administrative privileges because it can override the administrator's routing settings.
* The SO_BINDTODEVICE option restricts both outbound and inbound traffic, IP_UNICAST_IF only impacts outbound traffic.
IP_PKTINFO:
* Since IP_PKTINFO and IP_UNICAST_IF are independent options, implementing IP_UNICAST_IF with IP_PKTINFO will likely break some applications.
* Implementing IP_UNICAST_IF on top of IP_PKTINFO significantly complicates the Wine codebase and reduces the socket performance (doing this requires a lot of extra communication between the "server" and "user" layers).
bind():
* bind() does not work on broadcast packets, IP_UNICAST_IF is specifically intended to work with broadcast packets.
* Like SO_BINDTODEVICE, bind() restricts both outbound and inbound traffic.
Signed-off-by: Erich E. Hoover <ehoover@...es.edu>
---
include/linux/in.h | 1 +
include/net/inet_sock.h | 2 ++
net/ipv4/ip_sockglue.c | 33 +++++++++++++++++++++++++++++++++
net/ipv4/ping.c | 3 ++-
net/ipv4/raw.c | 3 ++-
net/ipv4/udp.c | 3 ++-
6 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/include/linux/in.h b/include/linux/in.h
index 01129c0..e0337f1 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -111,6 +111,7 @@ struct in_addr {
#define MCAST_LEAVE_SOURCE_GROUP 47
#define MCAST_MSFILTER 48
#define IP_MULTICAST_ALL 49
+#define IP_UNICAST_IF 50
#define MCAST_EXCLUDE 0
#define MCAST_INCLUDE 1
diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index e3e4051..022f772 100644
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -132,6 +132,7 @@ struct rtable;
* @tos - TOS
* @mc_ttl - Multicasting TTL
* @is_icsk - is this an inet_connection_sock?
+ * @uc_index - Unicast outgoing device index
* @mc_index - Multicast device index
* @mc_list - Group array
* @cork - info to build ip hdr on each ip frag while socket is corked
@@ -167,6 +168,7 @@ struct inet_sock {
transparent:1,
mc_all:1,
nodefrag:1;
+ int uc_index;
int mc_index;
__be32 mc_addr;
struct ip_mc_socklist __rcu *mc_list;
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 8aa87c1..9125529 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -469,6 +469,7 @@ static int do_ip_setsockopt(struct sock *sk, int level,
(1<<IP_ROUTER_ALERT) | (1<<IP_FREEBIND) |
(1<<IP_PASSSEC) | (1<<IP_TRANSPARENT) |
(1<<IP_MINTTL) | (1<<IP_NODEFRAG))) ||
+ optname == IP_UNICAST_IF ||
optname == IP_MULTICAST_TTL ||
optname == IP_MULTICAST_ALL ||
optname == IP_MULTICAST_LOOP ||
@@ -628,6 +629,35 @@ static int do_ip_setsockopt(struct sock *sk, int level,
goto e_inval;
inet->mc_loop = !!val;
break;
+ case IP_UNICAST_IF:
+ {
+ struct net_device *dev = NULL;
+ int ifindex;
+
+ if (optlen != sizeof(int))
+ goto e_inval;
+
+ ifindex = (__force int)ntohl((__force __be32)val);
+ if (ifindex == 0) {
+ inet->uc_index = 0;
+ err = 0;
+ break;
+ }
+
+ dev = dev_get_by_index(sock_net(sk), ifindex);
+ err = -EADDRNOTAVAIL;
+ if (!dev)
+ break;
+ dev_put(dev);
+
+ err = -EINVAL;
+ if (sk->sk_bound_dev_if)
+ break;
+
+ inet->uc_index = ifindex;
+ err = 0;
+ break;
+ }
case IP_MULTICAST_IF:
{
struct ip_mreqn mreq;
@@ -1178,6 +1208,9 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
case IP_MULTICAST_LOOP:
val = inet->mc_loop;
break;
+ case IP_UNICAST_IF:
+ val = (__force int)htonl((__u32) inet->uc_index);
+ break;
case IP_MULTICAST_IF:
{
struct in_addr addr;
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index aea5a19..cfc82cf 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -556,7 +556,8 @@ static int ping_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
ipc.oif = inet->mc_index;
if (!saddr)
saddr = inet->mc_addr;
- }
+ } else if (!ipc.oif)
+ ipc.oif = inet->uc_index;
flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
RT_SCOPE_UNIVERSE, sk->sk_protocol,
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 3ccda5a..ab46630 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -563,7 +563,8 @@ static int raw_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
ipc.oif = inet->mc_index;
if (!saddr)
saddr = inet->mc_addr;
- }
+ } else if (!ipc.oif)
+ ipc.oif = inet->uc_index;
flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos,
RT_SCOPE_UNIVERSE,
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5d075b5..cd99f1a 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -917,7 +917,8 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
if (!saddr)
saddr = inet->mc_addr;
connected = 0;
- }
+ } else if (!ipc.oif)
+ ipc.oif = inet->uc_index;
if (connected)
rt = (struct rtable *)sk_dst_check(sk, 0);
--
1.7.5.4
--
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