* [PATCH 6.1 1/2] mptcp: use the workqueue to destroy unaccepted sockets
2023-03-23 17:49 [PATCH 6.1 0/2] mptcp: Stable backports for v6.1 Matthieu Baerts
@ 2023-03-23 17:49 ` Matthieu Baerts
2023-03-23 17:49 ` [PATCH 6.1 2/2] mptcp: fix UaF in listener shutdown Matthieu Baerts
2023-03-25 0:43 ` [PATCH 6.1 0/2] mptcp: Stable backports for v6.1 Sasha Levin
2 siblings, 0 replies; 4+ messages in thread
From: Matthieu Baerts @ 2023-03-23 17:49 UTC (permalink / raw)
To: Greg Kroah-Hartman, Sasha Levin
Cc: Paolo Abeni, stable, mptcp, Matthieu Baerts, Christoph Paasch,
Jakub Kicinski
From: Paolo Abeni <pabeni@redhat.com>
[ Upstream commit b6985b9b82954caa53f862d6059d06c0526254f0 ]
Backports notes: one simple conflict in net/mptcp/protocol.c with:
commit a5ef058dc4d9 ("net: introduce and use custom sockopt socket flag")
Where the two commits add a new line for different actions in the same
context in mptcp_stream_accept().
Christoph reported a UaF at token lookup time after having
refactored the passive socket initialization part:
BUG: KASAN: use-after-free in __token_bucket_busy+0x253/0x260
Read of size 4 at addr ffff88810698d5b0 by task syz-executor653/3198
CPU: 1 PID: 3198 Comm: syz-executor653 Not tainted 6.2.0-rc59af4eaa31c1f6c00c8f1e448ed99a45c66340dd5 #6
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0x91
print_report+0x16a/0x46f
kasan_report+0xad/0x130
__token_bucket_busy+0x253/0x260
mptcp_token_new_connect+0x13d/0x490
mptcp_connect+0x4ed/0x860
__inet_stream_connect+0x80e/0xd90
tcp_sendmsg_fastopen+0x3ce/0x710
mptcp_sendmsg+0xff1/0x1a20
inet_sendmsg+0x11d/0x140
__sys_sendto+0x405/0x490
__x64_sys_sendto+0xdc/0x1b0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
We need to properly clean-up all the paired MPTCP-level
resources and be sure to release the msk last, even when
the unaccepted subflow is destroyed by the TCP internals
via inet_child_forget().
We can re-use the existing MPTCP_WORK_CLOSE_SUBFLOW infra,
explicitly checking that for the critical scenario: the
closed subflow is the MPC one, the msk is not accepted and
eventually going through full cleanup.
With such change, __mptcp_destroy_sock() is always called
on msk sockets, even on accepted ones. We don't need anymore
to transiently drop one sk reference at msk clone time.
Please note this commit depends on the parent one:
mptcp: refactor passive socket initialization
Fixes: 58b09919626b ("mptcp: create msk early")
Cc: stable@vger.kernel.org
Reported-and-tested-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/347
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
net/mptcp/protocol.c | 41 +++++++++++++++++++++++++++++++----------
net/mptcp/protocol.h | 5 ++++-
net/mptcp/subflow.c | 17 ++++++++++++-----
3 files changed, 47 insertions(+), 16 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 777f795246ed..b679e8a430a8 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2357,7 +2357,6 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
goto out;
}
- sock_orphan(ssk);
subflow->disposable = 1;
/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
@@ -2365,7 +2364,20 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
* reference owned by msk;
*/
if (!inet_csk(ssk)->icsk_ulp_ops) {
+ WARN_ON_ONCE(!sock_flag(ssk, SOCK_DEAD));
kfree_rcu(subflow, rcu);
+ } else if (msk->in_accept_queue && msk->first == ssk) {
+ /* if the first subflow moved to a close state, e.g. due to
+ * incoming reset and we reach here before inet_child_forget()
+ * the TCP stack could later try to close it via
+ * inet_csk_listen_stop(), or deliver it to the user space via
+ * accept().
+ * We can't delete the subflow - or risk a double free - nor let
+ * the msk survive - or will be leaked in the non accept scenario:
+ * fallback and let TCP cope with the subflow cleanup.
+ */
+ WARN_ON_ONCE(sock_flag(ssk, SOCK_DEAD));
+ mptcp_subflow_drop_ctx(ssk);
} else {
/* otherwise tcp will dispose of the ssk and subflow ctx */
if (ssk->sk_state == TCP_LISTEN) {
@@ -2412,9 +2424,10 @@ static unsigned int mptcp_sync_mss(struct sock *sk, u32 pmtu)
return 0;
}
-static void __mptcp_close_subflow(struct mptcp_sock *msk)
+static void __mptcp_close_subflow(struct sock *sk)
{
struct mptcp_subflow_context *subflow, *tmp;
+ struct mptcp_sock *msk = mptcp_sk(sk);
might_sleep();
@@ -2428,7 +2441,15 @@ static void __mptcp_close_subflow(struct mptcp_sock *msk)
if (!skb_queue_empty_lockless(&ssk->sk_receive_queue))
continue;
- mptcp_close_ssk((struct sock *)msk, ssk, subflow);
+ mptcp_close_ssk(sk, ssk, subflow);
+ }
+
+ /* if the MPC subflow has been closed before the msk is accepted,
+ * msk will never be accept-ed, close it now
+ */
+ if (!msk->first && msk->in_accept_queue) {
+ sock_set_flag(sk, SOCK_DEAD);
+ inet_sk_state_store(sk, TCP_CLOSE);
}
}
@@ -2637,6 +2658,9 @@ static void mptcp_worker(struct work_struct *work)
__mptcp_check_send_data_fin(sk);
mptcp_check_data_fin(sk);
+ if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
+ __mptcp_close_subflow(sk);
+
/* There is no point in keeping around an orphaned sk timedout or
* closed, but we need the msk around to reply to incoming DATA_FIN,
* even if it is orphaned and in FIN_WAIT2 state
@@ -2652,9 +2676,6 @@ static void mptcp_worker(struct work_struct *work)
}
}
- if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
- __mptcp_close_subflow(msk);
-
if (test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags))
__mptcp_retrans(sk);
@@ -3084,6 +3105,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
msk->local_key = subflow_req->local_key;
msk->token = subflow_req->token;
msk->subflow = NULL;
+ msk->in_accept_queue = 1;
WRITE_ONCE(msk->fully_established, false);
if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD)
WRITE_ONCE(msk->csum_enabled, true);
@@ -3110,8 +3132,7 @@ struct sock *mptcp_sk_clone(const struct sock *sk,
security_inet_csk_clone(nsk, req);
bh_unlock_sock(nsk);
- /* keep a single reference */
- __sock_put(nsk);
+ /* note: the newly allocated socket refcount is 2 now */
return nsk;
}
@@ -3167,8 +3188,6 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
goto out;
}
- /* acquire the 2nd reference for the owning socket */
- sock_hold(new_mptcp_sock);
newsk = new_mptcp_sock;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEPASSIVEACK);
} else {
@@ -3726,6 +3745,8 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
struct mptcp_subflow_context *subflow;
struct sock *newsk = newsock->sk;
+ msk->in_accept_queue = 0;
+
lock_sock(newsk);
/* set ssk->sk_socket of accept()ed flows to mptcp socket.
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 6f22ae13c984..2cddd5b52e8f 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -286,7 +286,8 @@ struct mptcp_sock {
u8 recvmsg_inq:1,
cork:1,
nodelay:1,
- fastopening:1;
+ fastopening:1,
+ in_accept_queue:1;
int connect_flags;
struct work_struct work;
struct sk_buff *ooo_last_skb;
@@ -651,6 +652,8 @@ void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow);
bool mptcp_subflow_active(struct mptcp_subflow_context *subflow);
+void mptcp_subflow_drop_ctx(struct sock *ssk);
+
static inline void mptcp_subflow_tcp_fallback(struct sock *sk,
struct mptcp_subflow_context *ctx)
{
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index fe815103060c..459621a0410c 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -636,9 +636,10 @@ static bool subflow_hmac_valid(const struct request_sock *req,
static void mptcp_force_close(struct sock *sk)
{
- /* the msk is not yet exposed to user-space */
+ /* the msk is not yet exposed to user-space, and refcount is 2 */
inet_sk_state_store(sk, TCP_CLOSE);
sk_common_release(sk);
+ sock_put(sk);
}
static void subflow_ulp_fallback(struct sock *sk,
@@ -654,7 +655,7 @@ static void subflow_ulp_fallback(struct sock *sk,
mptcp_subflow_ops_undo_override(sk);
}
-static void subflow_drop_ctx(struct sock *ssk)
+void mptcp_subflow_drop_ctx(struct sock *ssk)
{
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
@@ -758,7 +759,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
if (new_msk)
mptcp_copy_inaddrs(new_msk, child);
- subflow_drop_ctx(child);
+ mptcp_subflow_drop_ctx(child);
goto out;
}
@@ -849,7 +850,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
return child;
dispose_child:
- subflow_drop_ctx(child);
+ mptcp_subflow_drop_ctx(child);
tcp_rsk(req)->drop_req = true;
inet_csk_prepare_for_destroy_sock(child);
tcp_done(child);
@@ -1804,7 +1805,6 @@ void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_s
struct sock *sk = (struct sock *)msk;
bool do_cancel_work;
- sock_hold(sk);
lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
next = msk->dl_next;
msk->first = NULL;
@@ -1892,6 +1892,13 @@ static void subflow_ulp_release(struct sock *ssk)
* when the subflow is still unaccepted
*/
release = ctx->disposable || list_empty(&ctx->node);
+
+ /* inet_child_forget() does not call sk_state_change(),
+ * explicitly trigger the socket close machinery
+ */
+ if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
+ &mptcp_sk(sk)->flags))
+ mptcp_schedule_work(sk);
sock_put(sk);
}
--
2.39.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 6.1 2/2] mptcp: fix UaF in listener shutdown
2023-03-23 17:49 [PATCH 6.1 0/2] mptcp: Stable backports for v6.1 Matthieu Baerts
2023-03-23 17:49 ` [PATCH 6.1 1/2] mptcp: use the workqueue to destroy unaccepted sockets Matthieu Baerts
@ 2023-03-23 17:49 ` Matthieu Baerts
2023-03-25 0:43 ` [PATCH 6.1 0/2] mptcp: Stable backports for v6.1 Sasha Levin
2 siblings, 0 replies; 4+ messages in thread
From: Matthieu Baerts @ 2023-03-23 17:49 UTC (permalink / raw)
To: Greg Kroah-Hartman, Sasha Levin
Cc: Paolo Abeni, stable, mptcp, Matthieu Baerts, Christoph Paasch,
Jakub Kicinski
From: Paolo Abeni <pabeni@redhat.com>
[ Upstream commit 0a3f4f1f9c27215e4ddcd312558342e57b93e518 ]
Backports notes: one simple conflict in net/mptcp/protocol.c with:
commit f8c9dfbd875b ("mptcp: add pm listener events")
Where one commit removes code in __mptcp_close_ssk() while the other
one adds one line at the same place. We can simply remove the whole
condition because this extra instruction is not present in v6.1.
As reported by Christoph after having refactored the passive
socket initialization, the mptcp listener shutdown path is prone
to an UaF issue.
BUG: KASAN: use-after-free in _raw_spin_lock_bh+0x73/0xe0
Write of size 4 at addr ffff88810cb23098 by task syz-executor731/1266
CPU: 1 PID: 1266 Comm: syz-executor731 Not tainted 6.2.0-rc59af4eaa31c1f6c00c8f1e448ed99a45c66340dd5 #6
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x6e/0x91
print_report+0x16a/0x46f
kasan_report+0xad/0x130
kasan_check_range+0x14a/0x1a0
_raw_spin_lock_bh+0x73/0xe0
subflow_error_report+0x6d/0x110
sk_error_report+0x3b/0x190
tcp_disconnect+0x138c/0x1aa0
inet_child_forget+0x6f/0x2e0
inet_csk_listen_stop+0x209/0x1060
__mptcp_close_ssk+0x52d/0x610
mptcp_destroy_common+0x165/0x640
mptcp_destroy+0x13/0x80
__mptcp_destroy_sock+0xe7/0x270
__mptcp_close+0x70e/0x9b0
mptcp_close+0x2b/0x150
inet_release+0xe9/0x1f0
__sock_release+0xd2/0x280
sock_close+0x15/0x20
__fput+0x252/0xa20
task_work_run+0x169/0x250
exit_to_user_mode_prepare+0x113/0x120
syscall_exit_to_user_mode+0x1d/0x40
do_syscall_64+0x48/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc
The msk grace period can legitly expire in between the last
reference count dropped in mptcp_subflow_queue_clean() and
the later eventual access in inet_csk_listen_stop()
After the previous patch we don't need anymore special-casing
msk listener socket cleanup: the mptcp worker will process each
of the unaccepted msk sockets.
Just drop the now unnecessary code.
Please note this commit depends on the two parent ones:
mptcp: refactor passive socket initialization
mptcp: use the workqueue to destroy unaccepted sockets
Fixes: 6aeed9045071 ("mptcp: fix race on unaccepted mptcp sockets")
Cc: stable@vger.kernel.org
Reported-and-tested-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/346
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
---
net/mptcp/protocol.c | 5 ----
net/mptcp/protocol.h | 1 -
net/mptcp/subflow.c | 72 ----------------------------------------------------
3 files changed, 78 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index b679e8a430a8..f0cde2d7233d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2380,11 +2380,6 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
mptcp_subflow_drop_ctx(ssk);
} else {
/* otherwise tcp will dispose of the ssk and subflow ctx */
- if (ssk->sk_state == TCP_LISTEN) {
- tcp_set_state(ssk, TCP_CLOSE);
- mptcp_subflow_queue_clean(sk, ssk);
- inet_csk_listen_stop(ssk);
- }
__tcp_close(ssk, 0);
/* close acquired an extra ref */
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 2cddd5b52e8f..051e8022d661 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -615,7 +615,6 @@ void mptcp_close_ssk(struct sock *sk, struct sock *ssk,
struct mptcp_subflow_context *subflow);
void __mptcp_subflow_send_ack(struct sock *ssk);
void mptcp_subflow_reset(struct sock *ssk);
-void mptcp_subflow_queue_clean(struct sock *sk, struct sock *ssk);
void mptcp_sock_graft(struct sock *sk, struct socket *parent);
struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk);
bool __mptcp_close(struct sock *sk, long timeout);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 459621a0410c..fc876c248002 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -1764,78 +1764,6 @@ static void subflow_state_change(struct sock *sk)
}
}
-void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
-{
- struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
- struct mptcp_sock *msk, *next, *head = NULL;
- struct request_sock *req;
-
- /* build a list of all unaccepted mptcp sockets */
- spin_lock_bh(&queue->rskq_lock);
- for (req = queue->rskq_accept_head; req; req = req->dl_next) {
- struct mptcp_subflow_context *subflow;
- struct sock *ssk = req->sk;
- struct mptcp_sock *msk;
-
- if (!sk_is_mptcp(ssk))
- continue;
-
- subflow = mptcp_subflow_ctx(ssk);
- if (!subflow || !subflow->conn)
- continue;
-
- /* skip if already in list */
- msk = mptcp_sk(subflow->conn);
- if (msk->dl_next || msk == head)
- continue;
-
- msk->dl_next = head;
- head = msk;
- }
- spin_unlock_bh(&queue->rskq_lock);
- if (!head)
- return;
-
- /* can't acquire the msk socket lock under the subflow one,
- * or will cause ABBA deadlock
- */
- release_sock(listener_ssk);
-
- for (msk = head; msk; msk = next) {
- struct sock *sk = (struct sock *)msk;
- bool do_cancel_work;
-
- lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
- next = msk->dl_next;
- msk->first = NULL;
- msk->dl_next = NULL;
-
- do_cancel_work = __mptcp_close(sk, 0);
- release_sock(sk);
- if (do_cancel_work) {
- /* lockdep will report a false positive ABBA deadlock
- * between cancel_work_sync and the listener socket.
- * The involved locks belong to different sockets WRT
- * the existing AB chain.
- * Using a per socket key is problematic as key
- * deregistration requires process context and must be
- * performed at socket disposal time, in atomic
- * context.
- * Just tell lockdep to consider the listener socket
- * released here.
- */
- mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
- mptcp_cancel_work(sk);
- mutex_acquire(&listener_sk->sk_lock.dep_map,
- SINGLE_DEPTH_NESTING, 0, _RET_IP_);
- }
- sock_put(sk);
- }
-
- /* we are still under the listener msk socket lock */
- lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
-}
-
static int subflow_ulp_init(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
--
2.39.2
^ permalink raw reply related [flat|nested] 4+ messages in thread