forked from Minki/linux
Merge branch 'l2tp-tunnel-creation-fixes'
Guillaume Nault says: ==================== l2tp: tunnel creation fixes L2TP tunnel creation is racy. We need to make sure that the tunnel returned by l2tp_tunnel_create() isn't going to be freed while the caller is using it. This is done in patch #1, by separating tunnel creation from tunnel registration. With the tunnel registration code in place, we can now check for duplicate tunnels in a race-free way. This is done in patch #2, which incidentally removes the last use of l2tp_tunnel_find(). ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
commit
0c84cee8f1
@ -335,26 +335,6 @@ err_tlock:
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(l2tp_session_register);
|
||||
|
||||
/* Lookup a tunnel by id
|
||||
*/
|
||||
struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id)
|
||||
{
|
||||
struct l2tp_tunnel *tunnel;
|
||||
struct l2tp_net *pn = l2tp_pernet(net);
|
||||
|
||||
rcu_read_lock_bh();
|
||||
list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
|
||||
if (tunnel->tunnel_id == tunnel_id) {
|
||||
rcu_read_unlock_bh();
|
||||
return tunnel;
|
||||
}
|
||||
}
|
||||
rcu_read_unlock_bh();
|
||||
|
||||
return NULL;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
|
||||
|
||||
struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth)
|
||||
{
|
||||
struct l2tp_net *pn = l2tp_pernet(net);
|
||||
@ -1436,74 +1416,11 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
|
||||
{
|
||||
struct l2tp_tunnel *tunnel = NULL;
|
||||
int err;
|
||||
struct socket *sock = NULL;
|
||||
struct sock *sk = NULL;
|
||||
struct l2tp_net *pn;
|
||||
enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
|
||||
|
||||
/* Get the tunnel socket from the fd, which was opened by
|
||||
* the userspace L2TP daemon. If not specified, create a
|
||||
* kernel socket.
|
||||
*/
|
||||
if (fd < 0) {
|
||||
err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id,
|
||||
cfg, &sock);
|
||||
if (err < 0)
|
||||
goto err;
|
||||
} else {
|
||||
sock = sockfd_lookup(fd, &err);
|
||||
if (!sock) {
|
||||
pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n",
|
||||
tunnel_id, fd, err);
|
||||
err = -EBADF;
|
||||
goto err;
|
||||
}
|
||||
|
||||
/* Reject namespace mismatches */
|
||||
if (!net_eq(sock_net(sock->sk), net)) {
|
||||
pr_err("tunl %u: netns mismatch\n", tunnel_id);
|
||||
err = -EINVAL;
|
||||
goto err;
|
||||
}
|
||||
}
|
||||
|
||||
sk = sock->sk;
|
||||
|
||||
if (cfg != NULL)
|
||||
encap = cfg->encap;
|
||||
|
||||
/* Quick sanity checks */
|
||||
err = -EPROTONOSUPPORT;
|
||||
if (sk->sk_type != SOCK_DGRAM) {
|
||||
pr_debug("tunl %hu: fd %d wrong socket type\n",
|
||||
tunnel_id, fd);
|
||||
goto err;
|
||||
}
|
||||
switch (encap) {
|
||||
case L2TP_ENCAPTYPE_UDP:
|
||||
if (sk->sk_protocol != IPPROTO_UDP) {
|
||||
pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
|
||||
tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP);
|
||||
goto err;
|
||||
}
|
||||
break;
|
||||
case L2TP_ENCAPTYPE_IP:
|
||||
if (sk->sk_protocol != IPPROTO_L2TP) {
|
||||
pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n",
|
||||
tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP);
|
||||
goto err;
|
||||
}
|
||||
break;
|
||||
}
|
||||
|
||||
/* Check if this socket has already been prepped */
|
||||
tunnel = l2tp_tunnel(sk);
|
||||
if (tunnel != NULL) {
|
||||
/* This socket has already been prepped */
|
||||
err = -EBUSY;
|
||||
goto err;
|
||||
}
|
||||
|
||||
tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
|
||||
if (tunnel == NULL) {
|
||||
err = -ENOMEM;
|
||||
@ -1520,72 +1437,126 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
|
||||
rwlock_init(&tunnel->hlist_lock);
|
||||
tunnel->acpt_newsess = true;
|
||||
|
||||
/* The net we belong to */
|
||||
tunnel->l2tp_net = net;
|
||||
pn = l2tp_pernet(net);
|
||||
|
||||
if (cfg != NULL)
|
||||
tunnel->debug = cfg->debug;
|
||||
|
||||
/* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
|
||||
tunnel->encap = encap;
|
||||
if (encap == L2TP_ENCAPTYPE_UDP) {
|
||||
struct udp_tunnel_sock_cfg udp_cfg = { };
|
||||
|
||||
udp_cfg.sk_user_data = tunnel;
|
||||
udp_cfg.encap_type = UDP_ENCAP_L2TPINUDP;
|
||||
udp_cfg.encap_rcv = l2tp_udp_encap_recv;
|
||||
udp_cfg.encap_destroy = l2tp_udp_encap_destroy;
|
||||
|
||||
setup_udp_tunnel_sock(net, sock, &udp_cfg);
|
||||
} else {
|
||||
sk->sk_user_data = tunnel;
|
||||
}
|
||||
|
||||
/* Bump the reference count. The tunnel context is deleted
|
||||
* only when this drops to zero. A reference is also held on
|
||||
* the tunnel socket to ensure that it is not released while
|
||||
* the tunnel is extant. Must be done before sk_destruct is
|
||||
* set.
|
||||
*/
|
||||
refcount_set(&tunnel->ref_count, 1);
|
||||
sock_hold(sk);
|
||||
tunnel->sock = sk;
|
||||
tunnel->fd = fd;
|
||||
|
||||
/* Hook on the tunnel socket destructor so that we can cleanup
|
||||
* if the tunnel socket goes away.
|
||||
*/
|
||||
tunnel->old_sk_destruct = sk->sk_destruct;
|
||||
sk->sk_destruct = &l2tp_tunnel_destruct;
|
||||
lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock");
|
||||
|
||||
sk->sk_allocation = GFP_ATOMIC;
|
||||
|
||||
/* Init delete workqueue struct */
|
||||
INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
|
||||
|
||||
/* Add tunnel to our list */
|
||||
INIT_LIST_HEAD(&tunnel->list);
|
||||
spin_lock_bh(&pn->l2tp_tunnel_list_lock);
|
||||
list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
|
||||
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
|
||||
|
||||
err = 0;
|
||||
err:
|
||||
if (tunnelp)
|
||||
*tunnelp = tunnel;
|
||||
|
||||
/* If tunnel's socket was created by the kernel, it doesn't
|
||||
* have a file.
|
||||
*/
|
||||
if (sock && sock->file)
|
||||
sockfd_put(sock);
|
||||
|
||||
return err;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
|
||||
|
||||
static int l2tp_validate_socket(const struct sock *sk, const struct net *net,
|
||||
enum l2tp_encap_type encap)
|
||||
{
|
||||
if (!net_eq(sock_net(sk), net))
|
||||
return -EINVAL;
|
||||
|
||||
if (sk->sk_type != SOCK_DGRAM)
|
||||
return -EPROTONOSUPPORT;
|
||||
|
||||
if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) ||
|
||||
(encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP))
|
||||
return -EPROTONOSUPPORT;
|
||||
|
||||
if (sk->sk_user_data)
|
||||
return -EBUSY;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
|
||||
struct l2tp_tunnel_cfg *cfg)
|
||||
{
|
||||
struct l2tp_tunnel *tunnel_walk;
|
||||
struct l2tp_net *pn;
|
||||
struct socket *sock;
|
||||
struct sock *sk;
|
||||
int ret;
|
||||
|
||||
if (tunnel->fd < 0) {
|
||||
ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id,
|
||||
tunnel->peer_tunnel_id, cfg,
|
||||
&sock);
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
} else {
|
||||
sock = sockfd_lookup(tunnel->fd, &ret);
|
||||
if (!sock)
|
||||
goto err;
|
||||
|
||||
ret = l2tp_validate_socket(sock->sk, net, tunnel->encap);
|
||||
if (ret < 0)
|
||||
goto err_sock;
|
||||
}
|
||||
|
||||
sk = sock->sk;
|
||||
|
||||
sock_hold(sk);
|
||||
tunnel->sock = sk;
|
||||
tunnel->l2tp_net = net;
|
||||
|
||||
pn = l2tp_pernet(net);
|
||||
|
||||
spin_lock_bh(&pn->l2tp_tunnel_list_lock);
|
||||
list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) {
|
||||
if (tunnel_walk->tunnel_id == tunnel->tunnel_id) {
|
||||
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
|
||||
|
||||
ret = -EEXIST;
|
||||
goto err_sock;
|
||||
}
|
||||
}
|
||||
list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
|
||||
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
|
||||
|
||||
if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
|
||||
struct udp_tunnel_sock_cfg udp_cfg = {
|
||||
.sk_user_data = tunnel,
|
||||
.encap_type = UDP_ENCAP_L2TPINUDP,
|
||||
.encap_rcv = l2tp_udp_encap_recv,
|
||||
.encap_destroy = l2tp_udp_encap_destroy,
|
||||
};
|
||||
|
||||
setup_udp_tunnel_sock(net, sock, &udp_cfg);
|
||||
} else {
|
||||
sk->sk_user_data = tunnel;
|
||||
}
|
||||
|
||||
tunnel->old_sk_destruct = sk->sk_destruct;
|
||||
sk->sk_destruct = &l2tp_tunnel_destruct;
|
||||
lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class,
|
||||
"l2tp_sock");
|
||||
sk->sk_allocation = GFP_ATOMIC;
|
||||
|
||||
if (tunnel->fd >= 0)
|
||||
sockfd_put(sock);
|
||||
|
||||
return 0;
|
||||
|
||||
err_sock:
|
||||
if (tunnel->fd < 0)
|
||||
sock_release(sock);
|
||||
else
|
||||
sockfd_put(sock);
|
||||
err:
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(l2tp_tunnel_register);
|
||||
|
||||
/* This function is used by the netlink TUNNEL_DELETE command.
|
||||
*/
|
||||
void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
|
||||
|
||||
@ -220,12 +220,14 @@ struct l2tp_session *l2tp_session_get(const struct net *net,
|
||||
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
|
||||
struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
|
||||
const char *ifname);
|
||||
struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id);
|
||||
struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
|
||||
|
||||
int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
|
||||
u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,
|
||||
struct l2tp_tunnel **tunnelp);
|
||||
int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
|
||||
struct l2tp_tunnel_cfg *cfg);
|
||||
|
||||
void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel);
|
||||
void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel);
|
||||
struct l2tp_session *l2tp_session_create(int priv_size,
|
||||
|
||||
@ -236,12 +236,6 @@ static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info
|
||||
if (info->attrs[L2TP_ATTR_DEBUG])
|
||||
cfg.debug = nla_get_u32(info->attrs[L2TP_ATTR_DEBUG]);
|
||||
|
||||
tunnel = l2tp_tunnel_find(net, tunnel_id);
|
||||
if (tunnel != NULL) {
|
||||
ret = -EEXIST;
|
||||
goto out;
|
||||
}
|
||||
|
||||
ret = -EINVAL;
|
||||
switch (cfg.encap) {
|
||||
case L2TP_ENCAPTYPE_UDP:
|
||||
@ -251,9 +245,19 @@ static int l2tp_nl_cmd_tunnel_create(struct sk_buff *skb, struct genl_info *info
|
||||
break;
|
||||
}
|
||||
|
||||
if (ret >= 0)
|
||||
ret = l2tp_tunnel_notify(&l2tp_nl_family, info,
|
||||
tunnel, L2TP_CMD_TUNNEL_CREATE);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
|
||||
l2tp_tunnel_inc_refcount(tunnel);
|
||||
ret = l2tp_tunnel_register(tunnel, net, &cfg);
|
||||
if (ret < 0) {
|
||||
kfree(tunnel);
|
||||
goto out;
|
||||
}
|
||||
ret = l2tp_tunnel_notify(&l2tp_nl_family, info, tunnel,
|
||||
L2TP_CMD_TUNNEL_CREATE);
|
||||
l2tp_tunnel_dec_refcount(tunnel);
|
||||
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
@ -698,6 +698,15 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
|
||||
error = l2tp_tunnel_create(sock_net(sk), fd, ver, tunnel_id, peer_tunnel_id, &tcfg, &tunnel);
|
||||
if (error < 0)
|
||||
goto end;
|
||||
|
||||
l2tp_tunnel_inc_refcount(tunnel);
|
||||
error = l2tp_tunnel_register(tunnel, sock_net(sk),
|
||||
&tcfg);
|
||||
if (error < 0) {
|
||||
kfree(tunnel);
|
||||
goto end;
|
||||
}
|
||||
drop_tunnel = true;
|
||||
}
|
||||
} else {
|
||||
/* Error if we can't find the tunnel */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user