[PATCH net-next RFC v1 24/27] afnetns: check afnetns user_ns in inet6_bind

[Hannes Frederic Sowa]

Signed-off-by: Hannes Frederic Sowa <han...@stressinduktion.org>
---
 net/ipv6/af_inet6.c | 40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 30aff01eba5be0..4aa221826e753c 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -273,6 +273,26 @@ static int inet6_create(struct net *net, struct socket 
*sock, int protocol,
        goto out;
 }
 
+static int inet6_allow_bind(struct net *net, struct in6_addr *addr,
+                           unsigned short snum, struct net_device *dev)
+{
+       struct user_namespace *user_ns;
+#if IS_ENABLED(CONFIG_AFNETNS)
+       struct afnetns *afnetns;
+
+       afnetns = ipv6_get_ifaddr_afnetns_rcu(net, addr, dev);
+       user_ns = afnetns ? afnetns->user_ns : net->user_ns;
+#else
+       user_ns = net->user_ns;
+#endif
+
+       if (snum && snum < inet_prot_sock(net) &&
+           !ns_capable(user_ns, CAP_NET_BIND_SERVICE))
+               return -EADDRNOTAVAIL;
+
+       return 0;
+}
+
 
 /* bind for INET6 API */
 int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
@@ -301,11 +321,6 @@ int inet6_bind(struct socket *sock, struct sockaddr 
*uaddr, int addr_len)
        if ((addr_type & IPV6_ADDR_MULTICAST) && sock->type == SOCK_STREAM)
                return -EINVAL;
 
-       snum = ntohs(addr->sin6_port);
-       if (snum && snum < inet_prot_sock(net) &&
-           !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE))
-               return -EACCES;
-
        lock_sock(sk);
 
        /* Check these errors (active socket, double bind). */
@@ -314,6 +329,8 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, 
int addr_len)
                goto out;
        }
 
+       snum = ntohs(addr->sin6_port);
+
        /* Check if the address belongs to the host. */
        if (addr_type == IPV6_ADDR_MAPPED) {
                /* Binding to v4-mapped address on a v6-only socket
@@ -330,10 +347,12 @@ int inet6_bind(struct socket *sock, struct sockaddr 
*uaddr, int addr_len)
                else
                        err = 0;
        } else {
+               struct net_device *dev = NULL;
+
+               rcu_read_lock();
+
                if (addr_type != IPV6_ADDR_ANY) {
-                       struct net_device *dev = NULL;
 
-                       rcu_read_lock();
                        if (__ipv6_addr_needs_scope_id(addr_type)) {
                                if (addr_len >= sizeof(struct sockaddr_in6) &&
                                    addr->sin6_scope_id) {
@@ -371,8 +390,13 @@ int inet6_bind(struct socket *sock, struct sockaddr 
*uaddr, int addr_len)
                                        goto out_unlock;
                                }
                        }
-                       rcu_read_unlock();
                }
+
+               err = inet6_allow_bind(net, &addr->sin6_addr, snum, dev);
+               if (err)
+                       goto out_unlock;
+
+               rcu_read_unlock();
        }
 
        inet->inet_rcv_saddr = v4addr;
-- 
2.9.3