linux-user: Add support for setsockopt() options IPV6_<ADD|DROP>_MEMBERSHIP

Add support for the option IPV6_<ADD|DROP>_MEMBERSHIP of the syscall
setsockopt(). This option controls membership in multicast groups.
Argument is a pointer to a struct ipv6_mreq.

The glibc <netinet/in.h> header defines the ipv6_mreq structure,
which includes the following members:

  struct in6_addr  ipv6mr_multiaddr;
  unsigned int     ipv6mr_interface;

Whereas the kernel in its <linux/in6.h> header defines following
members of the same structure:

  struct in6_addr  ipv6mr_multiaddr;
  int              ipv6mr_ifindex;

POSIX defines ipv6mr_interface [1].

__UAPI_DEF_IVP6_MREQ appears in kernel headers with v3.12:

  cfd280c91253 net: sync some IP headers with glibc

Without __UAPI_DEF_IVP6_MREQ, kernel defines ipv6mr_ifindex, and
this is explained in cfd280c91253:

  "If you include the kernel headers first you get those,
  and if you include the glibc headers first you get those,
  and the following patch arranges a coordination and
  synchronization between the two."

So before 3.12, a program can't include both <netinet/in.h> and
<linux/in6.h>.

In linux-user/syscall.c, we only include <netinet/in.h> (glibc) and
not <linux/in6.h> (kernel headers), so ipv6mr_interface is the one
to use.

[1] http://pubs.opengroup.org/onlinepubs/009695399/basedefs/netinet/in.h.html

Signed-off-by: Neng Chen <nchen@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <1560953834-29584-2-git-send-email-aleksandar.markovic@rt-rk.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 19 insertions, 0 deletions

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ed1c9b0..d2c9817 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1892,6 +1892,25 @@ static abi_long do_setsockopt(int sockfd, int level, int optname,
                                        &pki, sizeof(pki)));
             break;
         }
+        case IPV6_ADD_MEMBERSHIP:
+        case IPV6_DROP_MEMBERSHIP:
+        {
+            struct ipv6_mreq ipv6mreq;
+
+            if (optlen < sizeof(ipv6mreq)) {
+                return -TARGET_EINVAL;
+            }
+
+            if (copy_from_user(&ipv6mreq, optval_addr, sizeof(ipv6mreq))) {
+                return -TARGET_EFAULT;
+            }
+
+            ipv6mreq.ipv6mr_interface = tswap32(ipv6mreq.ipv6mr_interface);
+
+            ret = get_errno(setsockopt(sockfd, level, optname,
+                                       &ipv6mreq, sizeof(ipv6mreq)));
+            break;
+        }
         default:
             goto unimplemented;
         }