net-ipv6: add support for sockopt(SOL_IPV6, IPV6_FREEBIND)
So far we've been relying on sockopt(SOL_IP, IP_FREEBIND) being usable
even on IPv6 sockets.
However, it turns out it is perfectly reasonable to want to set freebind
on an AF_INET6 SOCK_RAW socket - but there is no way to set any SOL_IP
socket option on such a socket (they're all blindly errored out).
One use case for this is to allow spoofing src ip on a raw socket
via sendmsg cmsg.
Tested:
built, and booted
# python
>>> import socket
>>> SOL_IP = socket.SOL_IP
>>> SOL_IPV6 = socket.IPPROTO_IPV6
>>> IP_FREEBIND = 15
>>> IPV6_FREEBIND = 78
>>> s = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM, 0)
>>> s.getsockopt(SOL_IP, IP_FREEBIND)
0
>>> s.getsockopt(SOL_IPV6, IPV6_FREEBIND)
0
>>> s.setsockopt(SOL_IPV6, IPV6_FREEBIND, 1)
>>> s.getsockopt(SOL_IP, IP_FREEBIND)
1
>>> s.getsockopt(SOL_IPV6, IPV6_FREEBIND)
1
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index a5e466d..b9404fe 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -377,6 +377,14 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
retv = 0;
break;
+ case IPV6_FREEBIND:
+ if (optlen < sizeof(int))
+ goto e_inval;
+ /* we also don't have a separate freebind bit for IPV6 */
+ inet_sk(sk)->freebind = valbool;
+ retv = 0;
+ break;
+
case IPV6_RECVORIGDSTADDR:
if (optlen < sizeof(int))
goto e_inval;
@@ -1214,6 +1222,10 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
val = inet_sk(sk)->transparent;
break;
+ case IPV6_FREEBIND:
+ val = inet_sk(sk)->freebind;
+ break;
+
case IPV6_RECVORIGDSTADDR:
val = np->rxopt.bits.rxorigdstaddr;
break;