[NETLINK]: Add set/getsockopt options to support more than 32 groups

NETLINK_ADD_MEMBERSHIP/NETLINK_DROP_MEMBERSHIP are used to join/leave
groups, NETLINK_PKTINFO is used to enable nl_pktinfo control messages
for received packets to get the extended destination group number.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 103 insertions, 2 deletions

diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index c724c9d4984a..36a40449f9f1 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -90,6 +90,15 @@ struct nlmsgerr
         struct nlmsghdr msg;
 };
 
+#define NETLINK_ADD_MEMBERSHIP  1
+#define NETLINK_DROP_MEMBERSHIP 2
+#define NETLINK_PKTINFO         3
+
+struct nl_pktinfo
+{
+        __u32   group;
+};
+
 #define NET_MAJOR 36            /* Major 36 is reserved for networking                                          */
 
 enum {
diff --git a/include/linux/socket.h b/include/linux/socket.h
index ddf22559f484..acc55aac8a43 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -272,6 +272,7 @@ struct ucred {
 #define SOL_NETBEUI     267
 #define SOL_LLC         268
 #define SOL_DCCP        269
+#define SOL_NETLINK     270
 
 /* IPX options */
 #define IPX_TYPE        1
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 58d4ca42ac32..47e791738014 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -81,6 +81,7 @@ struct netlink_sock {
 };
 
 #define NETLINK_KERNEL_SOCKET   0x1
+#define NETLINK_RECV_PKTINFO    0x2
 
 static inline struct netlink_sock *nlk_sk(struct sock *sk)
 {
@@ -946,6 +947,94 @@ void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
         read_unlock(&nl_table_lock);
 }
 
+static int netlink_setsockopt(struct socket *sock, int level, int optname,
+                              char __user *optval, int optlen)
+{
+        struct sock *sk = sock->sk;
+        struct netlink_sock *nlk = nlk_sk(sk);
+        int val = 0, err;
+
+        if (level != SOL_NETLINK)
+                return -ENOPROTOOPT;
+
+        if (optlen >= sizeof(int) &&
+            get_user(val, (int __user *)optval))
+                return -EFAULT;
+
+        switch (optname) {
+        case NETLINK_PKTINFO:
+                if (val)
+                        nlk->flags |= NETLINK_RECV_PKTINFO;
+                else
+                        nlk->flags &= ~NETLINK_RECV_PKTINFO;
+                err = 0;
+                break;
+        case NETLINK_ADD_MEMBERSHIP:
+        case NETLINK_DROP_MEMBERSHIP: {
+                unsigned int subscriptions;
+                int old, new = optname == NETLINK_ADD_MEMBERSHIP ? 1 : 0;
+
+                if (!netlink_capable(sock, NL_NONROOT_RECV))
+                        return -EPERM;
+                if (!val || val - 1 >= nlk->ngroups)
+                        return -EINVAL;
+                netlink_table_grab();
+                old = test_bit(val - 1, nlk->groups);
+                subscriptions = nlk->subscriptions - old + new;
+                if (new)
+                        __set_bit(val - 1, nlk->groups);
+                else
+                        __clear_bit(val - 1, nlk->groups);
+                netlink_update_subscriptions(sk, subscriptions);
+                netlink_table_ungrab();
+                err = 0;
+                break;
+        }
+        default:
+                err = -ENOPROTOOPT;
+        }
+        return err;
+}
+
+static int netlink_getsockopt(struct socket *sock, int level, int optname,
+                              char __user *optval, int __user *optlen)
+{
+        struct sock *sk = sock->sk;
+        struct netlink_sock *nlk = nlk_sk(sk);
+        int len, val, err;
+
+        if (level != SOL_NETLINK)
+                return -ENOPROTOOPT;
+
+        if (get_user(len, optlen))
+                return -EFAULT;
+        if (len < 0)
+                return -EINVAL;
+
+        switch (optname) {
+        case NETLINK_PKTINFO:
+                if (len < sizeof(int))
+                        return -EINVAL;
+                len = sizeof(int);
+                val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0;
+                put_user(len, optlen);
+                put_user(val, optval);
+                err = 0;
+                break;
+        default:
+                err = -ENOPROTOOPT;
+        }
+        return err;
+}
+
+static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
+{
+        struct nl_pktinfo info;
+
+        info.group = NETLINK_CB(skb).dst_group;
+        put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
+}
+
 static inline void netlink_rcv_wake(struct sock *sk)
 {
         struct netlink_sock *nlk = nlk_sk(sk);
@@ -1091,6 +1180,8 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
                 netlink_dump(sk);
 
         scm_recv(sock, msg, siocb->scm, flags);
+        if (nlk->flags & NETLINK_RECV_PKTINFO)
+                netlink_cmsg_recv_pktinfo(msg, skb);
 
 out:
         netlink_rcv_wake(sk);
@@ -1465,8 +1556,8 @@ static struct proto_ops netlink_ops = {
         .ioctl =        sock_no_ioctl,
         .listen =       sock_no_listen,
         .shutdown =     sock_no_shutdown,
-        .setsockopt =   sock_no_setsockopt,
-        .getsockopt =   sock_no_getsockopt,
+        .setsockopt =   netlink_setsockopt,
+        .getsockopt =   netlink_getsockopt,
         .sendmsg =      netlink_sendmsg,
         .recvmsg =      netlink_recvmsg,
         .mmap =         sock_no_mmap,