Commit 76e21053 authored by Erich E. Hoover's avatar Erich E. Hoover Committed by David S. Miller
Browse files

ipv4: 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: default avatarErich E. Hoover <ehoover@mines.edu>
Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 43480aec

include/linux/in.h

+1 −0
Original line number Diff line number Diff line
@@ -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

include/net/inet_sock.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

net/ipv4/ip_sockglue.c

+33 −0
Original line number Diff line number Diff line
@@ -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;

net/ipv4/ping.c

+2 −1
Original line number Diff line number Diff line
@@ -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,

net/ipv4/raw.c

+2 −1
Original line number Diff line number Diff line
@@ -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,

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