[NETLINK]: Don't prevent creating sockets when no kernel socket is registered

This broke the pam audit module which includes an incorrect check for
-ENOENT instead of -EPROTONOTSUPP.

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

1 files changed, 41 insertions, 18 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 62435ffc6184..a64e1d5ce3ca 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -398,24 +398,13 @@ static int netlink_create(struct socket *sock, int protocol)
         if (nl_table[protocol].registered &&
             try_module_get(nl_table[protocol].module))
                 module = nl_table[protocol].module;
-        else
-                err = -EPROTONOSUPPORT;
         groups = nl_table[protocol].groups;
         netlink_unlock_table();
 
-        if (err || (err = __netlink_create(sock, protocol) < 0))
+        if ((err = __netlink_create(sock, protocol) < 0))
                 goto out_module;
 
         nlk = nlk_sk(sock->sk);
-
-        nlk->groups = kmalloc(NLGRPSZ(groups), GFP_KERNEL);
-        if (nlk->groups == NULL) {
-                err = -ENOMEM;
-                goto out_module;
-        }
-        memset(nlk->groups, 0, NLGRPSZ(groups));
-        nlk->ngroups = groups;
-
         nlk->module = module;
 out:
         return err;
@@ -534,6 +523,29 @@ netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
         nlk->subscriptions = subscriptions;
 }
 
+static int netlink_alloc_groups(struct sock *sk)
+{
+        struct netlink_sock *nlk = nlk_sk(sk);
+        unsigned int groups;
+        int err = 0;
+
+        netlink_lock_table();
+        groups = nl_table[sk->sk_protocol].groups;
+        if (!nl_table[sk->sk_protocol].registered)
+                err = -ENOENT;
+        netlink_unlock_table();
+
+        if (err)
+                return err;
+
+        nlk->groups = kmalloc(NLGRPSZ(groups), GFP_KERNEL);
+        if (nlk->groups == NULL)
+                return -ENOMEM;
+        memset(nlk->groups, 0, NLGRPSZ(groups));
+        nlk->ngroups = groups;
+        return 0;
+}
+
 static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 {
         struct sock *sk = sock->sk;
@@ -545,8 +557,15 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len
                 return -EINVAL;
 
         /* Only superuser is allowed to listen multicasts */
-        if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_RECV))
-                return -EPERM;
+        if (nladdr->nl_groups) {
+                if (!netlink_capable(sock, NL_NONROOT_RECV))
+                        return -EPERM;
+                if (nlk->groups == NULL) {
+                        err = netlink_alloc_groups(sk);
+                        if (err)
+                                return err;
+                }
+        }
 
         if (nlk->pid) {
                 if (nladdr->nl_pid != nlk->pid)
@@ -559,7 +578,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len
                         return err;
         }
 
-        if (!nladdr->nl_groups && !(u32)nlk->groups[0])
+        if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
                 return 0;
 
         netlink_table_grab();
@@ -620,7 +639,7 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr, int *addr
                 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
         } else {
                 nladdr->nl_pid = nlk->pid;
-                nladdr->nl_groups = nlk->groups[0];
+                nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
         }
         return 0;
 }
@@ -976,6 +995,11 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
 
                 if (!netlink_capable(sock, NL_NONROOT_RECV))
                         return -EPERM;
+                if (nlk->groups == NULL) {
+                        err = netlink_alloc_groups(sk);
+                        if (err)
+                                return err;
+                }
                 if (!val || val - 1 >= nlk->ngroups)
                         return -EINVAL;
                 netlink_table_grab();
@@ -1483,8 +1507,7 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
                            s,
                            s->sk_protocol,
                            nlk->pid,
-                           nlk->flags & NETLINK_KERNEL_SOCKET ?
-                                0 : (unsigned int)nlk->groups[0],
+                           nlk->groups ? (u32)nlk->groups[0] : 0,
                            atomic_read(&s->sk_rmem_alloc),
                            atomic_read(&s->sk_wmem_alloc),
                            nlk->cb,