linux/net/mptcp/pm.c

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// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP
*
* Copyright (c) 2019, Intel Corporation.
*/
#define pr_fmt(fmt) "MPTCP: " fmt
#include <linux/kernel.h>
#include <net/tcp.h>
#include <net/mptcp.h>
#include "protocol.h"
/* path manager command handlers */
int mptcp_pm_announce_addr(struct mptcp_sock *msk,
const struct mptcp_addr_info *addr,
bool echo, bool port)
{
u8 add_addr = READ_ONCE(msk->pm.addr_signal);
pr_debug("msk=%p, local_id=%d", msk, addr->id);
lockdep_assert_held(&msk->pm.lock);
if (add_addr) {
pr_warn("addr_signal error, add_addr=%d", add_addr);
return -EINVAL;
}
msk->pm.local = *addr;
add_addr |= BIT(MPTCP_ADD_ADDR_SIGNAL);
if (echo)
add_addr |= BIT(MPTCP_ADD_ADDR_ECHO);
if (addr->family == AF_INET6)
add_addr |= BIT(MPTCP_ADD_ADDR_IPV6);
if (port)
add_addr |= BIT(MPTCP_ADD_ADDR_PORT);
WRITE_ONCE(msk->pm.addr_signal, add_addr);
return 0;
}
int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
{
u8 rm_addr = READ_ONCE(msk->pm.addr_signal);
pr_debug("msk=%p, local_id=%d", msk, local_id);
if (rm_addr) {
pr_warn("addr_signal error, rm_addr=%d", rm_addr);
return -EINVAL;
}
msk->pm.rm_id = local_id;
rm_addr |= BIT(MPTCP_RM_ADDR_SIGNAL);
WRITE_ONCE(msk->pm.addr_signal, rm_addr);
return 0;
}
int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 local_id)
{
pr_debug("msk=%p, local_id=%d", msk, local_id);
spin_lock_bh(&msk->pm.lock);
mptcp_pm_nl_rm_subflow_received(msk, local_id);
spin_unlock_bh(&msk->pm.lock);
return 0;
}
/* path manager event handlers */
void mptcp_pm_new_connection(struct mptcp_sock *msk, const struct sock *ssk, int server_side)
{
struct mptcp_pm_data *pm = &msk->pm;
pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
WRITE_ONCE(pm->server_side, server_side);
mptcp_event(MPTCP_EVENT_CREATED, msk, ssk, GFP_ATOMIC);
}
bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
{
struct mptcp_pm_data *pm = &msk->pm;
unsigned int subflows_max;
int ret = 0;
subflows_max = mptcp_pm_get_subflows_max(msk);
pr_debug("msk=%p subflows=%d max=%d allow=%d", msk, pm->subflows,
subflows_max, READ_ONCE(pm->accept_subflow));
/* try to avoid acquiring the lock below */
if (!READ_ONCE(pm->accept_subflow))
return false;
spin_lock_bh(&pm->lock);
if (READ_ONCE(pm->accept_subflow)) {
ret = pm->subflows < subflows_max;
if (ret && ++pm->subflows == subflows_max)
WRITE_ONCE(pm->accept_subflow, false);
}
spin_unlock_bh(&pm->lock);
return ret;
}
/* return true if the new status bit is currently cleared, that is, this event
* can be server, eventually by an already scheduled work
*/
static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
enum mptcp_pm_status new_status)
{
pr_debug("msk=%p status=%x new=%lx", msk, msk->pm.status,
BIT(new_status));
if (msk->pm.status & BIT(new_status))
return false;
msk->pm.status |= BIT(new_status);
mptcp_schedule_work((struct sock *)msk);
return true;
}
void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk, gfp_t gfp)
{
struct mptcp_pm_data *pm = &msk->pm;
bool announce = false;
pr_debug("msk=%p", msk);
spin_lock_bh(&pm->lock);
mptcp: link MPC subflow into msk only after accept Christoph reported the following splat: WARNING: CPU: 0 PID: 4615 at net/ipv4/inet_connection_sock.c:1031 inet_csk_listen_stop+0x8e8/0xad0 net/ipv4/inet_connection_sock.c:1031 Modules linked in: CPU: 0 PID: 4615 Comm: syz-executor.4 Not tainted 5.9.0 #37 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:inet_csk_listen_stop+0x8e8/0xad0 net/ipv4/inet_connection_sock.c:1031 Code: 03 00 00 00 e8 79 b2 3d ff e9 ad f9 ff ff e8 1f 76 ba fe be 02 00 00 00 4c 89 f7 e8 62 b2 3d ff e9 14 f9 ff ff e8 08 76 ba fe <0f> 0b e9 97 f8 ff ff e8 fc 75 ba fe be 03 00 00 00 4c 89 f7 e8 3f RSP: 0018:ffffc900037f7948 EFLAGS: 00010293 RAX: ffff88810a349c80 RBX: ffff888114ee1b00 RCX: ffffffff827b14cd RDX: 0000000000000000 RSI: ffffffff827b1c38 RDI: 0000000000000005 RBP: ffff88810a2a8000 R08: ffff88810a349c80 R09: fffff520006fef1f R10: 0000000000000003 R11: fffff520006fef1e R12: ffff888114ee2d00 R13: dffffc0000000000 R14: 0000000000000001 R15: ffff888114ee1d68 FS: 00007f2ac1945700(0000) GS:ffff88811b400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffd44798bc0 CR3: 0000000109810002 CR4: 0000000000170ef0 Call Trace: __tcp_close+0xd86/0x1110 net/ipv4/tcp.c:2433 __mptcp_close_ssk+0x256/0x430 net/mptcp/protocol.c:1761 __mptcp_destroy_sock+0x49b/0x770 net/mptcp/protocol.c:2127 mptcp_close+0x62d/0x910 net/mptcp/protocol.c:2184 inet_release+0xe9/0x1f0 net/ipv4/af_inet.c:434 __sock_release+0xd2/0x280 net/socket.c:596 sock_close+0x15/0x20 net/socket.c:1277 __fput+0x276/0x960 fs/file_table.c:281 task_work_run+0x109/0x1d0 kernel/task_work.c:151 get_signal+0xe8f/0x1d40 kernel/signal.c:2561 arch_do_signal+0x88/0x1b60 arch/x86/kernel/signal.c:811 exit_to_user_mode_loop kernel/entry/common.c:161 [inline] exit_to_user_mode_prepare+0x9b/0xf0 kernel/entry/common.c:191 syscall_exit_to_user_mode+0x22/0x150 kernel/entry/common.c:266 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f2ac1254469 Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ff 49 2b 00 f7 d8 64 89 01 48 RSP: 002b:00007f2ac1944dc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffbf RBX: 000000000069bf00 RCX: 00007f2ac1254469 RDX: 0000000000000000 RSI: 0000000000008982 RDI: 0000000000000003 RBP: 000000000069bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000069bf0c R13: 00007ffeb53f178f R14: 00000000004668b0 R15: 0000000000000003 After commit 0397c6d85f9c ("mptcp: keep unaccepted MPC subflow into join list"), the msk's workqueue and/or PM can touch the MPC subflow - and acquire its socket lock - even if it's still unaccepted. If the above event races with the relevant listener socket close, we can end-up with the above splat. This change addresses the issue delaying the MPC socket insertion in conn_list at accept time - that is, partially reverting the blamed commit. We must additionally ensure that mptcp_pm_fully_established() happens after accept() time, or the PM will not be able to handle properly such event - conn_list could be empty otherwise. In the receive path, we check the subflow list node to ensure it is out of the listener queue. Be sure client subflows do not match transiently such condition moving them into the join list earlier at creation time. Since we now have multiple mptcp_pm_fully_established() call sites from different code-paths, said helper can now race with itself. Use an additional PM status bit to avoid multiple notifications. Reported-by: Christoph Paasch <cpaasch@apple.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/103 Fixes: 0397c6d85f9c ("mptcp: keep unaccepted MPC subflow into join list"), Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2020-12-09 19:03:29 +08:00
/* mptcp_pm_fully_established() can be invoked by multiple
* racing paths - accept() and check_fully_established()
* be sure to serve this event only once.
*/
if (READ_ONCE(pm->work_pending) &&
!(msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)))
mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
if ((msk->pm.status & BIT(MPTCP_PM_ALREADY_ESTABLISHED)) == 0)
announce = true;
msk->pm.status |= BIT(MPTCP_PM_ALREADY_ESTABLISHED);
spin_unlock_bh(&pm->lock);
if (announce)
mptcp_event(MPTCP_EVENT_ESTABLISHED, msk, ssk, gfp);
}
void mptcp_pm_connection_closed(struct mptcp_sock *msk)
{
pr_debug("msk=%p", msk);
}
void mptcp_pm_subflow_established(struct mptcp_sock *msk,
struct mptcp_subflow_context *subflow)
{
struct mptcp_pm_data *pm = &msk->pm;
pr_debug("msk=%p", msk);
if (!READ_ONCE(pm->work_pending))
return;
spin_lock_bh(&pm->lock);
if (READ_ONCE(pm->work_pending))
mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
spin_unlock_bh(&pm->lock);
}
void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
{
pr_debug("msk=%p", msk);
}
void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
const struct mptcp_addr_info *addr)
{
struct mptcp_pm_data *pm = &msk->pm;
pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
READ_ONCE(pm->accept_addr));
mptcp_event_addr_announced(msk, addr);
spin_lock_bh(&pm->lock);
if (!READ_ONCE(pm->accept_addr)) {
mptcp_pm_announce_addr(msk, addr, true, addr->port);
mptcp_pm_add_addr_send_ack(msk);
} else if (mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED)) {
pm->remote = *addr;
}
spin_unlock_bh(&pm->lock);
}
void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk)
{
if (!mptcp_pm_should_add_signal(msk))
return;
mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_SEND_ACK);
}
void mptcp_pm_rm_addr_received(struct mptcp_sock *msk, u8 rm_id)
{
struct mptcp_pm_data *pm = &msk->pm;
pr_debug("msk=%p remote_id=%d", msk, rm_id);
mptcp_event_addr_removed(msk, rm_id);
spin_lock_bh(&pm->lock);
mptcp_pm_schedule_work(msk, MPTCP_PM_RM_ADDR_RECEIVED);
pm->rm_id = rm_id;
spin_unlock_bh(&pm->lock);
}
void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
pr_debug("subflow->backup=%d, bkup=%d\n", subflow->backup, bkup);
subflow->backup = bkup;
mptcp_event(MPTCP_EVENT_SUB_PRIORITY, mptcp_sk(subflow->conn), sk, GFP_ATOMIC);
}
/* path manager helpers */
bool mptcp_pm_add_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
struct mptcp_addr_info *saddr, bool *echo, bool *port)
{
int ret = false;
spin_lock_bh(&msk->pm.lock);
/* double check after the lock is acquired */
if (!mptcp_pm_should_add_signal(msk))
goto out_unlock;
*echo = mptcp_pm_should_add_signal_echo(msk);
*port = mptcp_pm_should_add_signal_port(msk);
if (remaining < mptcp_add_addr_len(msk->pm.local.family, *echo, *port))
goto out_unlock;
*saddr = msk->pm.local;
WRITE_ONCE(msk->pm.addr_signal, 0);
ret = true;
out_unlock:
spin_unlock_bh(&msk->pm.lock);
return ret;
}
bool mptcp_pm_rm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
u8 *rm_id)
{
int ret = false;
spin_lock_bh(&msk->pm.lock);
/* double check after the lock is acquired */
if (!mptcp_pm_should_rm_signal(msk))
goto out_unlock;
if (remaining < TCPOLEN_MPTCP_RM_ADDR_BASE)
goto out_unlock;
*rm_id = msk->pm.rm_id;
WRITE_ONCE(msk->pm.addr_signal, 0);
ret = true;
out_unlock:
spin_unlock_bh(&msk->pm.lock);
return ret;
}
int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
{
return mptcp_pm_nl_get_local_id(msk, skc);
}
void mptcp_pm_data_init(struct mptcp_sock *msk)
{
msk->pm.add_addr_signaled = 0;
msk->pm.add_addr_accepted = 0;
msk->pm.local_addr_used = 0;
msk->pm.subflows = 0;
msk->pm.rm_id = 0;
WRITE_ONCE(msk->pm.work_pending, false);
WRITE_ONCE(msk->pm.addr_signal, 0);
WRITE_ONCE(msk->pm.accept_addr, false);
WRITE_ONCE(msk->pm.accept_subflow, false);
msk->pm.status = 0;
spin_lock_init(&msk->pm.lock);
INIT_LIST_HEAD(&msk->pm.anno_list);
mptcp_pm_nl_data_init(msk);
}
void __init mptcp_pm_init(void)
{
mptcp_pm_nl_init();
}