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Diffstat (limited to 'net/l2tp/l2tp_ppp.c')
-rw-r--r--net/l2tp/l2tp_ppp.c248
1 files changed, 155 insertions, 93 deletions
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 0c2738349442..5f5c78b632d0 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -122,8 +122,11 @@
struct pppol2tp_session {
int owner; /* pid that opened the socket */
- struct sock *sock; /* Pointer to the session
+ struct mutex sk_lock; /* Protects .sk */
+ struct sock __rcu *sk; /* Pointer to the session
* PPPoX socket */
+ struct sock *__sk; /* Copy of .sk, for cleanup */
+ struct rcu_head rcu; /* For asynchronous release */
struct sock *tunnel_sock; /* Pointer to the tunnel UDP
* socket */
int flags; /* accessed by PPPIOCGFLAGS.
@@ -138,6 +141,24 @@ static const struct ppp_channel_ops pppol2tp_chan_ops = {
static const struct proto_ops pppol2tp_ops;
+/* Retrieves the pppol2tp socket associated to a session.
+ * A reference is held on the returned socket, so this function must be paired
+ * with sock_put().
+ */
+static struct sock *pppol2tp_session_get_sock(struct l2tp_session *session)
+{
+ struct pppol2tp_session *ps = l2tp_session_priv(session);
+ struct sock *sk;
+
+ rcu_read_lock();
+ sk = rcu_dereference(ps->sk);
+ if (sk)
+ sock_hold(sk);
+ rcu_read_unlock();
+
+ return sk;
+}
+
/* Helpers to obtain tunnel/session contexts from sockets.
*/
static inline struct l2tp_session *pppol2tp_sock_to_session(struct sock *sk)
@@ -224,7 +245,8 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
/* If the socket is bound, send it in to PPP's input queue. Otherwise
* queue it on the session socket.
*/
- sk = ps->sock;
+ rcu_read_lock();
+ sk = rcu_dereference(ps->sk);
if (sk == NULL)
goto no_sock;
@@ -247,30 +269,16 @@ static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int
kfree_skb(skb);
}
}
+ rcu_read_unlock();
return;
no_sock:
+ rcu_read_unlock();
l2tp_info(session, L2TP_MSG_DATA, "%s: no socket\n", session->name);
kfree_skb(skb);
}
-static void pppol2tp_session_sock_hold(struct l2tp_session *session)
-{
- struct pppol2tp_session *ps = l2tp_session_priv(session);
-
- if (ps->sock)
- sock_hold(ps->sock);
-}
-
-static void pppol2tp_session_sock_put(struct l2tp_session *session)
-{
- struct pppol2tp_session *ps = l2tp_session_priv(session);
-
- if (ps->sock)
- sock_put(ps->sock);
-}
-
/************************************************************************
* Transmit handling
***********************************************************************/
@@ -431,17 +439,16 @@ abort:
*/
static void pppol2tp_session_close(struct l2tp_session *session)
{
- struct pppol2tp_session *ps = l2tp_session_priv(session);
- struct sock *sk = ps->sock;
- struct socket *sock = sk->sk_socket;
+ struct sock *sk;
BUG_ON(session->magic != L2TP_SESSION_MAGIC);
- if (sock)
- inet_shutdown(sock, SEND_SHUTDOWN);
-
- /* Don't let the session go away before our socket does */
- l2tp_session_inc_refcount(session);
+ sk = pppol2tp_session_get_sock(session);
+ if (sk) {
+ if (sk->sk_socket)
+ inet_shutdown(sk->sk_socket, SEND_SHUTDOWN);
+ sock_put(sk);
+ }
}
/* Really kill the session socket. (Called from sock_put() if
@@ -461,6 +468,14 @@ static void pppol2tp_session_destruct(struct sock *sk)
}
}
+static void pppol2tp_put_sk(struct rcu_head *head)
+{
+ struct pppol2tp_session *ps;
+
+ ps = container_of(head, typeof(*ps), rcu);
+ sock_put(ps->__sk);
+}
+
/* Called when the PPPoX socket (session) is closed.
*/
static int pppol2tp_release(struct socket *sock)
@@ -486,11 +501,23 @@ static int pppol2tp_release(struct socket *sock)
session = pppol2tp_sock_to_session(sk);
- /* Purge any queued data */
if (session != NULL) {
- __l2tp_session_unhash(session);
- l2tp_session_queue_purge(session);
- sock_put(sk);
+ struct pppol2tp_session *ps;
+
+ l2tp_session_delete(session);
+
+ ps = l2tp_session_priv(session);
+ mutex_lock(&ps->sk_lock);
+ ps->__sk = rcu_dereference_protected(ps->sk,
+ lockdep_is_held(&ps->sk_lock));
+ RCU_INIT_POINTER(ps->sk, NULL);
+ mutex_unlock(&ps->sk_lock);
+ call_rcu(&ps->rcu, pppol2tp_put_sk);
+
+ /* Rely on the sock_put() call at the end of the function for
+ * dropping the reference held by pppol2tp_sock_to_session().
+ * The last reference will be dropped by pppol2tp_put_sk().
+ */
}
release_sock(sk);
@@ -557,16 +584,47 @@ out:
static void pppol2tp_show(struct seq_file *m, void *arg)
{
struct l2tp_session *session = arg;
- struct pppol2tp_session *ps = l2tp_session_priv(session);
+ struct sock *sk;
+
+ sk = pppol2tp_session_get_sock(session);
+ if (sk) {
+ struct pppox_sock *po = pppox_sk(sk);
- if (ps) {
- struct pppox_sock *po = pppox_sk(ps->sock);
- if (po)
- seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan));
+ seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan));
+ sock_put(sk);
}
}
#endif
+static void pppol2tp_session_init(struct l2tp_session *session)
+{
+ struct pppol2tp_session *ps;
+ struct dst_entry *dst;
+
+ session->recv_skb = pppol2tp_recv;
+ session->session_close = pppol2tp_session_close;
+#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
+ session->show = pppol2tp_show;
+#endif
+
+ ps = l2tp_session_priv(session);
+ mutex_init(&ps->sk_lock);
+ ps->tunnel_sock = session->tunnel->sock;
+ ps->owner = current->pid;
+
+ /* If PMTU discovery was enabled, use the MTU that was discovered */
+ dst = sk_dst_get(session->tunnel->sock);
+ if (dst) {
+ u32 pmtu = dst_mtu(dst);
+
+ if (pmtu) {
+ session->mtu = pmtu - PPPOL2TP_HEADER_OVERHEAD;
+ session->mru = pmtu - PPPOL2TP_HEADER_OVERHEAD;
+ }
+ dst_release(dst);
+ }
+}
+
/* connect() handler. Attach a PPPoX socket to a tunnel UDP socket
*/
static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
@@ -578,7 +636,6 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
struct l2tp_session *session = NULL;
struct l2tp_tunnel *tunnel;
struct pppol2tp_session *ps;
- struct dst_entry *dst;
struct l2tp_session_cfg cfg = { 0, };
int error = 0;
u32 tunnel_id, peer_tunnel_id;
@@ -688,7 +745,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
if (tunnel->peer_tunnel_id == 0)
tunnel->peer_tunnel_id = peer_tunnel_id;
- session = l2tp_session_get(sock_net(sk), tunnel, session_id, false);
+ session = l2tp_session_get(sock_net(sk), tunnel, session_id);
if (session) {
drop_refcnt = true;
ps = l2tp_session_priv(session);
@@ -696,13 +753,17 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
/* Using a pre-existing session is fine as long as it hasn't
* been connected yet.
*/
- if (ps->sock) {
+ mutex_lock(&ps->sk_lock);
+ if (rcu_dereference_protected(ps->sk,
+ lockdep_is_held(&ps->sk_lock))) {
+ mutex_unlock(&ps->sk_lock);
error = -EEXIST;
goto end;
}
/* consistency checks */
if (ps->tunnel_sock != tunnel->sock) {
+ mutex_unlock(&ps->sk_lock);
error = -EEXIST;
goto end;
}
@@ -718,35 +779,19 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
error = PTR_ERR(session);
goto end;
}
- }
-
- /* Associate session with its PPPoL2TP socket */
- ps = l2tp_session_priv(session);
- ps->owner = current->pid;
- ps->sock = sk;
- ps->tunnel_sock = tunnel->sock;
-
- session->recv_skb = pppol2tp_recv;
- session->session_close = pppol2tp_session_close;
-#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
- session->show = pppol2tp_show;
-#endif
-
- /* We need to know each time a skb is dropped from the reorder
- * queue.
- */
- session->ref = pppol2tp_session_sock_hold;
- session->deref = pppol2tp_session_sock_put;
- /* If PMTU discovery was enabled, use the MTU that was discovered */
- dst = sk_dst_get(tunnel->sock);
- if (dst != NULL) {
- u32 pmtu = dst_mtu(dst);
+ pppol2tp_session_init(session);
+ ps = l2tp_session_priv(session);
+ l2tp_session_inc_refcount(session);
- if (pmtu != 0)
- session->mtu = session->mru = pmtu -
- PPPOL2TP_HEADER_OVERHEAD;
- dst_release(dst);
+ mutex_lock(&ps->sk_lock);
+ error = l2tp_session_register(session, tunnel);
+ if (error < 0) {
+ mutex_unlock(&ps->sk_lock);
+ kfree(session);
+ goto end;
+ }
+ drop_refcnt = true;
}
/* Special case: if source & dest session_id == 0x0000, this
@@ -771,12 +816,23 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
po->chan.mtu = session->mtu;
error = ppp_register_net_channel(sock_net(sk), &po->chan);
- if (error)
+ if (error) {
+ mutex_unlock(&ps->sk_lock);
goto end;
+ }
out_no_ppp:
/* This is how we get the session context from the socket. */
sk->sk_user_data = session;
+ rcu_assign_pointer(ps->sk, sk);
+ mutex_unlock(&ps->sk_lock);
+
+ /* Keep the reference we've grabbed on the session: sk doesn't expect
+ * the session to disappear. pppol2tp_session_destruct() is responsible
+ * for dropping it.
+ */
+ drop_refcnt = false;
+
sk->sk_state = PPPOX_CONNECTED;
l2tp_info(session, L2TP_MSG_CONTROL, "%s: created\n",
session->name);
@@ -800,12 +856,11 @@ static int pppol2tp_session_create(struct net *net, struct l2tp_tunnel *tunnel,
{
int error;
struct l2tp_session *session;
- struct pppol2tp_session *ps;
/* Error if tunnel socket is not prepped */
if (!tunnel->sock) {
error = -ENOENT;
- goto out;
+ goto err;
}
/* Default MTU values. */
@@ -820,18 +875,20 @@ static int pppol2tp_session_create(struct net *net, struct l2tp_tunnel *tunnel,
peer_session_id, cfg);
if (IS_ERR(session)) {
error = PTR_ERR(session);
- goto out;
+ goto err;
}
- ps = l2tp_session_priv(session);
- ps->tunnel_sock = tunnel->sock;
+ pppol2tp_session_init(session);
- l2tp_info(session, L2TP_MSG_CONTROL, "%s: created\n",
- session->name);
+ error = l2tp_session_register(session, tunnel);
+ if (error < 0)
+ goto err_sess;
- error = 0;
+ return 0;
-out:
+err_sess:
+ kfree(session);
+err:
return error;
}
@@ -992,12 +1049,10 @@ static int pppol2tp_session_ioctl(struct l2tp_session *session,
"%s: pppol2tp_session_ioctl(cmd=%#x, arg=%#lx)\n",
session->name, cmd, arg);
- sk = ps->sock;
+ sk = pppol2tp_session_get_sock(session);
if (!sk)
return -EBADR;
- sock_hold(sk);
-
switch (cmd) {
case SIOCGIFMTU:
err = -ENXIO;
@@ -1143,13 +1198,11 @@ static int pppol2tp_tunnel_ioctl(struct l2tp_tunnel *tunnel,
/* resend to session ioctl handler */
struct l2tp_session *session =
l2tp_session_get(sock_net(sk), tunnel,
- stats.session_id, true);
+ stats.session_id);
if (session) {
err = pppol2tp_session_ioctl(session, cmd,
arg);
- if (session->deref)
- session->deref(session);
l2tp_session_dec_refcount(session);
} else {
err = -EBADR;
@@ -1273,7 +1326,6 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
int optname, int val)
{
int err = 0;
- struct pppol2tp_session *ps = l2tp_session_priv(session);
switch (optname) {
case PPPOL2TP_SO_RECVSEQ:
@@ -1294,8 +1346,8 @@ static int pppol2tp_session_setsockopt(struct sock *sk,
}
session->send_seq = !!val;
{
- struct sock *ssk = ps->sock;
- struct pppox_sock *po = pppox_sk(ssk);
+ struct pppox_sock *po = pppox_sk(sk);
+
po->chan.hdrlen = val ? PPPOL2TP_L2TP_HDR_SIZE_SEQ :
PPPOL2TP_L2TP_HDR_SIZE_NOSEQ;
}
@@ -1566,7 +1618,7 @@ static void pppol2tp_next_tunnel(struct net *net, struct pppol2tp_seq_data *pd)
static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
{
- pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx, true);
+ pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
pd->session_idx++;
if (pd->session == NULL) {
@@ -1634,8 +1686,9 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
{
struct l2tp_session *session = v;
struct l2tp_tunnel *tunnel = session->tunnel;
- struct pppol2tp_session *ps = l2tp_session_priv(session);
- struct pppox_sock *po = pppox_sk(ps->sock);
+ unsigned char state;
+ char user_data_ok;
+ struct sock *sk;
u32 ip = 0;
u16 port = 0;
@@ -1645,6 +1698,15 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
port = ntohs(inet->inet_sport);
}
+ sk = pppol2tp_session_get_sock(session);
+ if (sk) {
+ state = sk->sk_state;
+ user_data_ok = (session == sk->sk_user_data) ? 'Y' : 'N';
+ } else {
+ state = 0;
+ user_data_ok = 'N';
+ }
+
seq_printf(m, " SESSION '%s' %08X/%d %04X/%04X -> "
"%04X/%04X %d %c\n",
session->name, ip, port,
@@ -1652,9 +1714,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
session->session_id,
tunnel->peer_tunnel_id,
session->peer_session_id,
- ps->sock->sk_state,
- (session == ps->sock->sk_user_data) ?
- 'Y' : 'N');
+ state, user_data_ok);
seq_printf(m, " %d/%d/%c/%c/%s %08x %u\n",
session->mtu, session->mru,
session->recv_seq ? 'R' : '-',
@@ -1671,8 +1731,12 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v)
atomic_long_read(&session->stats.rx_bytes),
atomic_long_read(&session->stats.rx_errors));
- if (po)
+ if (sk) {
+ struct pppox_sock *po = pppox_sk(sk);
+
seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan));
+ sock_put(sk);
+ }
}
static int pppol2tp_seq_show(struct seq_file *m, void *v)
@@ -1697,8 +1761,6 @@ static int pppol2tp_seq_show(struct seq_file *m, void *v)
pppol2tp_seq_tunnel_show(m, pd->tunnel);
} else {
pppol2tp_seq_session_show(m, pd->session);
- if (pd->session->deref)
- pd->session->deref(pd->session);
l2tp_session_dec_refcount(pd->session);
}