From: "phil.turnbull@oracle.com" phil.turnbull@oracle.com

commit 4ac36a4adaf80013a60013d6f829f5863d5d0e05 upstream.

If 'tunnel' is NULL we should return -EBADF but the 'end_put_sess' path unconditionally sets 'error' back to zero. Rework the error path so it more closely matches pppol2tp_sendmsg.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts") Signed-off-by: Phil Turnbull phil.turnbull@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Will Deacon will@kernel.org --- net/l2tp/l2tp_ppp.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index d3f1222c1a8c..bc5fca07d2ee 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -889,10 +889,8 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr,

pls = l2tp_session_priv(session); tunnel = l2tp_sock_to_tunnel(pls->tunnel_sock); - if (tunnel == NULL) { - error = -EBADF; + if (tunnel == NULL) goto end_put_sess; - }

inet = inet_sk(tunnel->sock); if ((tunnel->version == 2) && (tunnel->sock->sk_family == AF_INET)) { @@ -970,12 +968,11 @@ static int pppol2tp_getname(struct socket *sock, struct sockaddr *uaddr, }

*usockaddr_len = len; + error = 0;

sock_put(pls->tunnel_sock); end_put_sess: sock_put(sk); - error = 0; - end: return error; }

From: Guillaume Nault g.nault@alphalink.fr

commit 61b9a047729bb230978178bca6729689d0c50ca2 upstream.

Taking a reference on sessions in l2tp_recv_common() is racy; this has to be done by the callers.

To this end, a new function is required (l2tp_session_get()) to atomically lookup a session and take a reference on it. Callers then have to manually drop this reference.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts") Signed-off-by: Guillaume Nault g.nault@alphalink.fr Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Will Deacon will@kernel.org --- net/l2tp/l2tp_core.c | 73 ++++++++++++++++++++++++++++++++++++-------- net/l2tp/l2tp_core.h | 3 ++ net/l2tp/l2tp_ip.c | 17 ++++++++--- net/l2tp/l2tp_ip6.c | 18 ++++++++--- 4 files changed, 88 insertions(+), 23 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 429dbb064240..4d41fe40723d 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -277,6 +277,55 @@ struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunn } EXPORT_SYMBOL_GPL(l2tp_session_find);

+/* Like l2tp_session_find() but takes a reference on the returned session. + * Optionally calls session->ref() too if do_ref is true. + */ +struct l2tp_session *l2tp_session_get(struct net *net, + struct l2tp_tunnel *tunnel, + u32 session_id, bool do_ref) +{ + struct hlist_head *session_list; + struct l2tp_session *session; + + if (!tunnel) { + struct l2tp_net *pn = l2tp_pernet(net); + + session_list = l2tp_session_id_hash_2(pn, session_id); + + rcu_read_lock_bh(); + hlist_for_each_entry_rcu(session, session_list, global_hlist) { + if (session->session_id == session_id) { + l2tp_session_inc_refcount(session); + if (do_ref && session->ref) + session->ref(session); + rcu_read_unlock_bh(); + + return session; + } + } + rcu_read_unlock_bh(); + + return NULL; + } + + session_list = l2tp_session_id_hash(tunnel, session_id); + read_lock_bh(&tunnel->hlist_lock); + hlist_for_each_entry(session, session_list, hlist) { + if (session->session_id == session_id) { + l2tp_session_inc_refcount(session); + if (do_ref && session->ref) + session->ref(session); + read_unlock_bh(&tunnel->hlist_lock); + + return session; + } + } + read_unlock_bh(&tunnel->hlist_lock); + + return NULL; +} +EXPORT_SYMBOL_GPL(l2tp_session_get); + struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth, bool do_ref) { @@ -636,6 +685,9 @@ discard: * a data (not control) frame before coming here. Fields up to the * session-id have already been parsed and ptr points to the data * after the session-id. + * + * session->ref() must have been called prior to l2tp_recv_common(). + * session->deref() will be called automatically after skb is processed. */ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, unsigned char *ptr, unsigned char *optr, u16 hdrflags, @@ -645,14 +697,6 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, int offset; u32 ns, nr;

- /* The ref count is increased since we now hold a pointer to - * the session. Take care to decrement the refcnt when exiting - * this function from now on... - */ - l2tp_session_inc_refcount(session); - if (session->ref) - (*session->ref)(session); - /* Parse and check optional cookie */ if (session->peer_cookie_len > 0) { if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { @@ -803,8 +847,6 @@ void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, /* Try to dequeue as many skbs from reorder_q as we can. */ l2tp_recv_dequeue(session);

- l2tp_session_dec_refcount(session); - return;

discard: @@ -813,8 +855,6 @@ discard:

if (session->deref) (*session->deref)(session); - - l2tp_session_dec_refcount(session); } EXPORT_SYMBOL(l2tp_recv_common);

@@ -921,8 +961,14 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, }

/* Find the session context */ - session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id); + session = l2tp_session_get(tunnel->l2tp_net, tunnel, session_id, true); if (!session || !session->recv_skb) { + if (session) { + if (session->deref) + session->deref(session); + l2tp_session_dec_refcount(session); + } + /* Not found? Pass to userspace to deal with */ l2tp_info(tunnel, L2TP_MSG_DATA, "%s: no session found (%u/%u). Passing up.\n", @@ -935,6 +981,7 @@ static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, goto error;

l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook); + l2tp_session_dec_refcount(session);

return 0;

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h index fad47e9d74bc..705fbc63ddc2 100644 --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -243,6 +243,9 @@ out: return tunnel; }

+struct l2tp_session *l2tp_session_get(struct net *net, + struct l2tp_tunnel *tunnel, + u32 session_id, bool do_ref); struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id); diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index 7efb3cadc152..58f87bdd12c7 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -142,19 +142,19 @@ static int l2tp_ip_recv(struct sk_buff *skb) }

/* Ok, this is a data packet. Lookup the session. */ - session = l2tp_session_find(net, NULL, session_id); - if (session == NULL) + session = l2tp_session_get(net, NULL, session_id, true); + if (!session) goto discard;

tunnel = session->tunnel; - if (tunnel == NULL) - goto discard; + if (!tunnel) + goto discard_sess;

/* Trace packet contents, if enabled */ if (tunnel->debug & L2TP_MSG_DATA) { length = min(32u, skb->len); if (!pskb_may_pull(skb, length)) - goto discard; + goto discard_sess;

/* Point to L2TP header */ optr = ptr = skb->data; @@ -167,6 +167,7 @@ static int l2tp_ip_recv(struct sk_buff *skb) goto discard;

l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook); + l2tp_session_dec_refcount(session);

return 0;

@@ -204,6 +205,12 @@ pass_up:

return sk_receive_skb(sk, skb, 1);

+discard_sess: + if (session->deref) + session->deref(session); + l2tp_session_dec_refcount(session); + goto discard; + discard_put: sock_put(sk);

diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index 391dd9d8144f..af04a8a68269 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -154,19 +154,19 @@ static int l2tp_ip6_recv(struct sk_buff *skb) }

/* Ok, this is a data packet. Lookup the session. */ - session = l2tp_session_find(net, NULL, session_id); - if (session == NULL) + session = l2tp_session_get(net, NULL, session_id, true); + if (!session) goto discard;

tunnel = session->tunnel; - if (tunnel == NULL) - goto discard; + if (!tunnel) + goto discard_sess;

/* Trace packet contents, if enabled */ if (tunnel->debug & L2TP_MSG_DATA) { length = min(32u, skb->len); if (!pskb_may_pull(skb, length)) - goto discard; + goto discard_sess;

/* Point to L2TP header */ optr = ptr = skb->data; @@ -180,6 +180,8 @@ static int l2tp_ip6_recv(struct sk_buff *skb)

l2tp_recv_common(session, skb, ptr, optr, 0, skb->len, tunnel->recv_payload_hook); + l2tp_session_dec_refcount(session); + return 0;

pass_up: @@ -217,6 +219,12 @@ pass_up:

return sk_receive_skb(sk, skb, 1);

+discard_sess: + if (session->deref) + session->deref(session); + l2tp_session_dec_refcount(session); + goto discard; + discard_put: sock_put(sk);

From: Guillaume Nault g.nault@alphalink.fr

commit dbdbc73b44782e22b3b4b6e8b51e7a3d245f3086 upstream.

l2tp_session_create() relies on its caller for checking for duplicate sessions. This is racy since a session can be concurrently inserted after the caller's verification.

Fix this by letting l2tp_session_create() verify sessions uniqueness upon insertion. Callers need to be adapted to check for l2tp_session_create()'s return code instead of calling l2tp_session_find().

pppol2tp_connect() is a bit special because it has to work on existing sessions (if they're not connected) or to create a new session if none is found. When acting on a preexisting session, a reference must be held or it could go away on us. So we have to use l2tp_session_get() instead of l2tp_session_find() and drop the reference before exiting.

Fixes: d9e31d17ceba ("l2tp: Add L2TP ethernet pseudowire support") Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts") Signed-off-by: Guillaume Nault g.nault@alphalink.fr Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Will Deacon will@kernel.org --- net/l2tp/l2tp_core.c | 70 +++++++++++++++++++++++++++++++++----------- net/l2tp/l2tp_eth.c | 10 ++----- net/l2tp/l2tp_ppp.c | 60 ++++++++++++++++++------------------- 3 files changed, 84 insertions(+), 56 deletions(-)

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 4d41fe40723d..03475b124841 100644 --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -377,6 +377,48 @@ struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname) } EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname);

+static int l2tp_session_add_to_tunnel(struct l2tp_tunnel *tunnel, + struct l2tp_session *session) +{ + struct l2tp_session *session_walk; + struct hlist_head *g_head; + struct hlist_head *head; + struct l2tp_net *pn; + + head = l2tp_session_id_hash(tunnel, session->session_id); + + write_lock_bh(&tunnel->hlist_lock); + hlist_for_each_entry(session_walk, head, hlist) + if (session_walk->session_id == session->session_id) + goto exist; + + if (tunnel->version == L2TP_HDR_VER_3) { + pn = l2tp_pernet(tunnel->l2tp_net); + g_head = l2tp_session_id_hash_2(l2tp_pernet(tunnel->l2tp_net), + session->session_id); + + spin_lock_bh(&pn->l2tp_session_hlist_lock); + hlist_for_each_entry(session_walk, g_head, global_hlist) + if (session_walk->session_id == session->session_id) + goto exist_glob; + + hlist_add_head_rcu(&session->global_hlist, g_head); + spin_unlock_bh(&pn->l2tp_session_hlist_lock); + } + + hlist_add_head(&session->hlist, head); + write_unlock_bh(&tunnel->hlist_lock); + + return 0; + +exist_glob: + spin_unlock_bh(&pn->l2tp_session_hlist_lock); +exist: + write_unlock_bh(&tunnel->hlist_lock); + + return -EEXIST; +} + /* Lookup a tunnel by id */ struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id) @@ -1792,6 +1834,7 @@ EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg) { struct l2tp_session *session; + int err;

session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); if (session != NULL) { @@ -1847,6 +1890,13 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn

l2tp_session_set_header_len(session, tunnel->version);

+ err = l2tp_session_add_to_tunnel(tunnel, session); + if (err) { + kfree(session); + + return ERR_PTR(err); + } + /* Bump the reference count. The session context is deleted * only when this drops to zero. */ @@ -1856,28 +1906,14 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn /* Ensure tunnel socket isn't deleted */ sock_hold(tunnel->sock);

- /* Add session to the tunnel's hash list */ - write_lock_bh(&tunnel->hlist_lock); - hlist_add_head(&session->hlist, - l2tp_session_id_hash(tunnel, session_id)); - write_unlock_bh(&tunnel->hlist_lock); - - /* And to the global session list if L2TPv3 */ - if (tunnel->version != L2TP_HDR_VER_2) { - struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); - - spin_lock_bh(&pn->l2tp_session_hlist_lock); - hlist_add_head_rcu(&session->global_hlist, - l2tp_session_id_hash_2(pn, session_id)); - spin_unlock_bh(&pn->l2tp_session_hlist_lock); - } - /* Ignore management session in session count value */ if (session->session_id != 0) atomic_inc(&l2tp_session_count); + + return session; }

- return session; + return ERR_PTR(-ENOMEM); } EXPORT_SYMBOL_GPL(l2tp_session_create);

diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c index e253c26f31ac..c94160df71af 100644 --- a/net/l2tp/l2tp_eth.c +++ b/net/l2tp/l2tp_eth.c @@ -223,12 +223,6 @@ static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 p goto out; }

- session = l2tp_session_find(net, tunnel, session_id); - if (session) { - rc = -EEXIST; - goto out; - } - if (cfg->ifname) { dev = dev_get_by_name(net, cfg->ifname); if (dev) { @@ -242,8 +236,8 @@ static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 p

session = l2tp_session_create(sizeof(*spriv), tunnel, session_id, peer_session_id, cfg); - if (!session) { - rc = -ENOMEM; + if (IS_ERR(session)) { + rc = PTR_ERR(session); goto out; }

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index 74b211312d4d..97155145c0c5 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -600,6 +600,7 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr, int error = 0; u32 tunnel_id, peer_tunnel_id; u32 session_id, peer_session_id; + bool drop_refcnt = false; int ver = 2; int fd;

@@ -708,36 +709,36 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr, if (tunnel->peer_tunnel_id == 0) tunnel->peer_tunnel_id = peer_tunnel_id;

- /* Create session if it doesn't already exist. We handle the - * case where a session was previously created by the netlink - * interface by checking that the session doesn't already have - * a socket and its tunnel socket are what we expect. If any - * of those checks fail, return EEXIST to the caller. - */ - session = l2tp_session_find(sock_net(sk), tunnel, session_id); - if (session == NULL) { - /* Default MTU must allow space for UDP/L2TP/PPP - * headers. + session = l2tp_session_get(sock_net(sk), tunnel, session_id, false); + if (session) { + drop_refcnt = true; + ps = l2tp_session_priv(session); + + /* Using a pre-existing session is fine as long as it hasn't + * been connected yet. */ - cfg.mtu = cfg.mru = 1500 - PPPOL2TP_HEADER_OVERHEAD; + if (ps->sock) { + error = -EEXIST; + goto end; + }

- /* Allocate and initialize a new session context. */ - session = l2tp_session_create(sizeof(struct pppol2tp_session), - tunnel, session_id, - peer_session_id, &cfg); - if (session == NULL) { - error = -ENOMEM; + /* consistency checks */ + if (ps->tunnel_sock != tunnel->sock) { + error = -EEXIST; goto end; } } else { - ps = l2tp_session_priv(session); - error = -EEXIST; - if (ps->sock != NULL) - goto end; + /* Default MTU must allow space for UDP/L2TP/PPP headers */ + cfg.mtu = 1500 - PPPOL2TP_HEADER_OVERHEAD; + cfg.mru = cfg.mtu;

- /* consistency checks */ - if (ps->tunnel_sock != tunnel->sock) + session = l2tp_session_create(sizeof(struct pppol2tp_session), + tunnel, session_id, + peer_session_id, &cfg); + if (IS_ERR(session)) { + error = PTR_ERR(session); goto end; + } }

/* Associate session with its PPPoL2TP socket */ @@ -802,6 +803,8 @@ out_no_ppp: session->name);

end: + if (drop_refcnt) + l2tp_session_dec_refcount(session); release_sock(sk);

return error; @@ -829,12 +832,6 @@ static int pppol2tp_session_create(struct net *net, u32 tunnel_id, u32 session_i if (tunnel->sock == NULL) goto out;

- /* Check that this session doesn't already exist */ - error = -EEXIST; - session = l2tp_session_find(net, tunnel, session_id); - if (session != NULL) - goto out; - /* Default MTU values. */ if (cfg->mtu == 0) cfg->mtu = 1500 - PPPOL2TP_HEADER_OVERHEAD; @@ -842,12 +839,13 @@ static int pppol2tp_session_create(struct net *net, u32 tunnel_id, u32 session_i cfg->mru = cfg->mtu;

/* Allocate and initialize a new session context. */ - error = -ENOMEM; session = l2tp_session_create(sizeof(struct pppol2tp_session), tunnel, session_id, peer_session_id, cfg); - if (session == NULL) + if (IS_ERR(session)) { + error = PTR_ERR(session); goto out; + }

ps = l2tp_session_priv(session); ps->tunnel_sock = tunnel->sock;

From: Guillaume Nault g.nault@alphalink.fr

commit cdd10c9627496ad25c87ce6394e29752253c69d3 upstream.

If l2tp_tunnel_delete() or l2tp_tunnel_closeall() deletes a session right after pppol2tp_release() orphaned its socket, then the 'sock' variable of the pppol2tp_session_close() callback is NULL. Yet the session is still used by pppol2tp_release().

Therefore we need to take an extra reference in any case, to prevent l2tp_tunnel_delete() or l2tp_tunnel_closeall() from freeing the session.

Since the pppol2tp_session_close() callback is only set if the session is associated to a PPPOL2TP socket and that both l2tp_tunnel_delete() and l2tp_tunnel_closeall() hold the PPPOL2TP socket before calling pppol2tp_session_close(), we're sure that pppol2tp_session_close() and pppol2tp_session_destruct() are paired and called in the right order. So the reference taken by the former will be released by the later.

Signed-off-by: Guillaume Nault g.nault@alphalink.fr Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Will Deacon will@kernel.org --- net/l2tp/l2tp_ppp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index 98d4fa47b6a5..bc5d6b8f8ede 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -452,11 +452,11 @@ static void pppol2tp_session_close(struct l2tp_session *session)

BUG_ON(session->magic != L2TP_SESSION_MAGIC);

- if (sock) { + if (sock) inet_shutdown(sock, SEND_SHUTDOWN); - /* Don't let the session go away before our socket does */ - l2tp_session_inc_refcount(session); - } + + /* Don't let the session go away before our socket does */ + l2tp_session_inc_refcount(session); }

/* Really kill the session socket. (Called from sock_put() if