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authorDavid Herrmann <dh.herrmann@gmail.com>2015-06-17 15:14:33 (GMT)
committerDavid S. Miller <davem@davemloft.net>2015-06-21 17:18:18 (GMT)
commitb42be38b2778eda2237fc759e55e3b698b05b315 (patch)
tree52e997d4f7487cc1f09f503bb22df0a132d9dc1a /net/netlink
parente0df02e0c2118892b302e8248dbbb21698bedfed (diff)
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: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink')
-rw-r--r--net/netlink/af_netlink.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 69d67c3..dea9253 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -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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