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author | David S. Miller <davem@davemloft.net> | 2018-04-11 17:41:28 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2018-04-11 17:41:28 -0400 |
commit | 0c84cee8f131a090f77f5a3dea5d6a7bd99c00db (patch) | |
tree | f616d85bc1fa0339fc227d4672cea1f4b4042a30 | |
parent | 83c1f36f9880814b24cdf6c2f91f66f61db65326 (diff) | |
parent | f6cd651b056ffd3b4e8496afd44d4ed44bf69136 (diff) | |
download | linux-stable-0c84cee8f131a090f77f5a3dea5d6a7bd99c00db.tar.gz linux-stable-0c84cee8f131a090f77f5a3dea5d6a7bd99c00db.tar.bz2 linux-stable-0c84cee8f131a090f77f5a3dea5d6a7bd99c00db.zip |
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>
-rw-r--r-- | net/l2tp/l2tp_core.c | 225 | ||||
-rw-r--r-- | net/l2tp/l2tp_core.h | 4 | ||||
-rw-r--r-- | net/l2tp/l2tp_netlink.c | 22 | ||||
-rw-r--r-- | net/l2tp/l2tp_ppp.c | 9 |
4 files changed, 123 insertions, 137 deletions
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 14b67dfacc4b..0fbd3ee26165 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -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) diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h index 2718d0b284d0..ba33cbec71eb 100644 --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -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, diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c index e7ea9c4b89ff..b05dbd9ffcb2 100644 --- a/net/l2tp/l2tp_netlink.c +++ b/net/l2tp/l2tp_netlink.c @@ -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; } diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index d6deca11da19..896bbca9bdaa 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -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 */ |