Commit b42be38b authored by David Herrmann's avatar David Herrmann Committed by David S. Miller

netlink: add API to retrieve all group memberships

This patch adds getsockopt(SOL_NETLINK, NETLINK_LIST_MEMBERSHIPS) to
retrieve all groups a socket is a member of. Currently, we have to use
getsockname() and look at the nl.nl_groups bitmask. However, this mask is
limited to 32 groups. Hence, similar to NETLINK_ADD_MEMBERSHIP and
NETLINK_DROP_MEMBERSHIP, this adds a separate sockopt to manager higher
groups IDs than 32.

This new NETLINK_LIST_MEMBERSHIPS option takes a pointer to __u32 and the
size of the array. The array is filled with the full membership-set of the
socket, and the required array size is returned in optlen. Hence,
user-space can retry with a properly sized array in case it was too small.
Signed-off-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e0df02e0
......@@ -101,14 +101,15 @@ struct nlmsgerr {
struct nlmsghdr msg;
};
#define NETLINK_ADD_MEMBERSHIP 1
#define NETLINK_DROP_MEMBERSHIP 2
#define NETLINK_PKTINFO 3
#define NETLINK_BROADCAST_ERROR 4
#define NETLINK_NO_ENOBUFS 5
#define NETLINK_RX_RING 6
#define NETLINK_TX_RING 7
#define NETLINK_LISTEN_ALL_NSID 8
#define NETLINK_ADD_MEMBERSHIP 1
#define NETLINK_DROP_MEMBERSHIP 2
#define NETLINK_PKTINFO 3
#define NETLINK_BROADCAST_ERROR 4
#define NETLINK_NO_ENOBUFS 5
#define NETLINK_RX_RING 6
#define NETLINK_TX_RING 7
#define NETLINK_LISTEN_ALL_NSID 8
#define NETLINK_LIST_MEMBERSHIPS 9
struct nl_pktinfo {
__u32 group;
......
......@@ -2290,6 +2290,28 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
return -EFAULT;
err = 0;
break;
case NETLINK_LIST_MEMBERSHIPS: {
int pos, idx, shift;
err = 0;
netlink_table_grab();
for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
if (len - pos < sizeof(u32))
break;
idx = pos / sizeof(unsigned long);
shift = (pos % sizeof(unsigned long)) * 8;
if (put_user((u32)(nlk->groups[idx] >> shift),
(u32 __user *)(optval + pos))) {
err = -EFAULT;
break;
}
}
if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
err = -EFAULT;
netlink_table_ungrab();
break;
}
default:
err = -ENOPROTOOPT;
}
......
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