Commit message: net: rds: force to destroy connection if t_sock is NULL in rds_tcp_kill_sock().

When it is to cleanup net namespace, rds_tcp_exit_net() will call
rds_tcp_kill_sock(), if t_sock is NULL, it will not call
rds_conn_destroy(), rds_conn_path_destroy() and rds_tcp_conn_free() to free
connection, and the worker cp_conn_w is not stopped, afterwards the net is freed in
net_drop_ns(); While cp_conn_w rds_connect_worker() will call rds_tcp_conn_path_connect()
and reference 'net' which has already been freed.

In rds_tcp_conn_path_connect(), rds_tcp_set_callbacks() will set t_sock = sock before
sock->ops->connect, but if connect() is failed, it will call
rds_tcp_restore_callbacks() and set t_sock = NULL, if connect is always
failed, rds_connect_worker() will try to reconnect all the time, so
rds_tcp_kill_sock() will never to cancel worker cp_conn_w and free the
connections.

Therefore, the condition !tc->t_sock is not needed if it is going to do
cleanup_net->rds_tcp_exit_net->rds_tcp_kill_sock, because tc->t_sock is always
NULL, and there is on other path to cancel cp_conn_w and free
connection. So this patch is to fix this.

rds_tcp_kill_sock():
...
if (net != c_net || !tc->t_sock)
...
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

==================================================================
BUG: KASAN: use-after-free in inet_create+0xbcc/0xd28
net/ipv4/af_inet.c:340
Read of size 4 at addr ffff8003496a4684 by task kworker/u8:4/3721

CPU: 3 PID: 3721 Comm: kworker/u8:4 Not tainted 5.1.0 #11
Hardware name: linux,dummy-virt (DT)
Workqueue: krdsd rds_connect_worker
Call trace:
 dump_backtrace+0x0/0x3c0 arch/arm64/kernel/time.c:53
 show_stack+0x28/0x38 arch/arm64/kernel/traps.c:152
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x120/0x188 lib/dump_stack.c:113
 print_address_description+0x68/0x278 mm/kasan/report.c:253
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x21c/0x348 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x30/0x40 mm/kasan/report.c:429
 inet_create+0xbcc/0xd28 net/ipv4/af_inet.c:340
 __sock_create+0x4f8/0x770 net/socket.c:1276
 sock_create_kern+0x50/0x68 net/socket.c:1322
 rds_tcp_conn_path_connect+0x2b4/0x690 net/rds/tcp_connect.c:114
 rds_connect_worker+0x108/0x1d0 net/rds/threads.c:175
 process_one_work+0x6e8/0x1700 kernel/workqueue.c:2153
 worker_thread+0x3b0/0xdd0 kernel/workqueue.c:2296
 kthread+0x2f0/0x378 kernel/kthread.c:255
 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1117

Allocated by task 687:
 save_stack mm/kasan/kasan.c:448 [inline]
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xd4/0x180 mm/kasan/kasan.c:553
 kasan_slab_alloc+0x14/0x20 mm/kasan/kasan.c:490
 slab_post_alloc_hook mm/slab.h:444 [inline]
 slab_alloc_node mm/slub.c:2705 [inline]
 slab_alloc mm/slub.c:2713 [inline]
 kmem_cache_alloc+0x14c/0x388 mm/slub.c:2718
 kmem_cache_zalloc include/linux/slab.h:697 [inline]
 net_alloc net/core/net_namespace.c:384 [inline]
 copy_net_ns+0xc4/0x2d0 net/core/net_namespace.c:424
 create_new_namespaces+0x300/0x658 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xa0/0x198 kernel/nsproxy.c:206
 ksys_unshare+0x340/0x628 kernel/fork.c:2577
 __do_sys_unshare kernel/fork.c:2645 [inline]
 __se_sys_unshare kernel/fork.c:2643 [inline]
 __arm64_sys_unshare+0x38/0x58 kernel/fork.c:2643
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:47 [inline]
 el0_svc_common+0x168/0x390 arch/arm64/kernel/syscall.c:83
 el0_svc_handler+0x60/0xd0 arch/arm64/kernel/syscall.c:129
 el0_svc+0x8/0xc arch/arm64/kernel/entry.S:960

Freed by task 264:
 save_stack mm/kasan/kasan.c:448 [inline]
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x114/0x220 mm/kasan/kasan.c:521
 kasan_slab_free+0x10/0x18 mm/kasan/kasan.c:528
 slab_free_hook mm/slub.c:1370 [inline]
 slab_free_freelist_hook mm/slub.c:1397 [inline]
 slab_free mm/slub.c:2952 [inline]
 kmem_cache_free+0xb8/0x3a8 mm/slub.c:2968
 net_free net/core/net_namespace.c:400 [inline]
 net_drop_ns.part.6+0x78/0x90 net/core/net_namespace.c:407
 net_drop_ns net/core/net_namespace.c:406 [inline]
 cleanup_net+0x53c/0x6d8 net/core/net_namespace.c:569
 process_one_work+0x6e8/0x1700 kernel/workqueue.c:2153
 worker_thread+0x3b0/0xdd0 kernel/workqueue.c:2296
 kthread+0x2f0/0x378 kernel/kthread.c:255
 ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1117

The buggy address belongs to the object at ffff8003496a3f80
 which belongs to the cache net_namespace of size 7872
The buggy address is located 1796 bytes inside of
 7872-byte region [ffff8003496a3f80, ffff8003496a5e40)
The buggy address belongs to the page:
page:ffff7e000d25a800 count:1 mapcount:0 mapping:ffff80036ce4b000
index:0x0 compound_mapcount: 0
flags: 0xffffe0000008100(slab|head)
raw: 0ffffe0000008100 dead000000000100 dead000000000200 ffff80036ce4b000
raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8003496a4580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8003496a4600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8003496a4680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff8003496a4700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8003496a4780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Fixes: 467fa15356ac("RDS-TCP: Support multiple RDS-TCP listen endpoints, one per netns.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
CVE: CVE-2019-11815
CWE: CWE-362
Vulnerability description: An issue was discovered in rds_tcp_kill_sock in net/rds/tcp.c in the Linux kernel before 5.0.8. There is a race condition leading to a use-after-free, related to net namespace cleanup.

Project: linux
File: tcp.c

static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
{
	struct rds_tcp_connection *tc, *_tc;

	list_for_each_entry_safe(tc, _tc, list, t_tcp_node) {
		if (tc->t_cpath->cp_conn == conn)
			return true;
	}
	return false;
}

Project: linux
File: tcp.c

static void rds6_tcp_tc_info(struct socket *sock, unsigned int len,
			     struct rds_info_iterator *iter,
			     struct rds_info_lengths *lens)
{
	struct rds6_info_tcp_socket tsinfo6;
	struct rds_tcp_connection *tc;
	unsigned long flags;

	spin_lock_irqsave(&rds_tcp_tc_list_lock, flags);

	if (len / sizeof(tsinfo6) < rds6_tcp_tc_count)
		goto out;

	list_for_each_entry(tc, &rds_tcp_tc_list, t_list_item) {
		struct sock *sk = tc->t_sock->sk;
		struct inet_sock *inet = inet_sk(sk);

		tsinfo6.local_addr = sk->sk_v6_rcv_saddr;
		tsinfo6.local_port = inet->inet_sport;
		tsinfo6.peer_addr = sk->sk_v6_daddr;
		tsinfo6.peer_port = inet->inet_dport;

		tsinfo6.hdr_rem = tc->t_tinc_hdr_rem;
		tsinfo6.data_rem = tc->t_tinc_data_rem;
		tsinfo6.last_sent_nxt = tc->t_last_sent_nxt;
		tsinfo6.last_expected_una = tc->t_last_expected_una;
		tsinfo6.last_seen_una = tc->t_last_seen_una;

		rds_info_copy(iter, &tsinfo6, sizeof(tsinfo6));
	}

out:
	lens->nr = rds6_tcp_tc_count;
	lens->each = sizeof(tsinfo6);

	spin_unlock_irqrestore(&rds_tcp_tc_list_lock, flags);
}

Project: linux
File: tcp.c

void rds_tcp_accept_work(struct sock *sk)
{
	struct net *net = sock_net(sk);
	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);

	queue_work(rds_wq, &rtn->rds_tcp_accept_w);
}

Project: linux
File: tcp.c

static void rds_tcp_accept_worker(struct work_struct *work)
{
	struct rds_tcp_net *rtn = container_of(work,
					       struct rds_tcp_net,
					       rds_tcp_accept_w);

	while (rds_tcp_accept_one(rtn->rds_tcp_listen_sock) == 0)
		cond_resched();
}

Project: linux
File: tcp.c

static void rds_tcp_destroy_conns(void)
{
	struct rds_tcp_connection *tc, *_tc;
	LIST_HEAD(tmp_list);

	/* avoid calling conn_destroy with irqs off */
	spin_lock_irq(&rds_tcp_conn_lock);
	list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
		if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
			list_move_tail(&tc->t_tcp_node, &tmp_list);
	}
	spin_unlock_irq(&rds_tcp_conn_lock);

	list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
		rds_conn_destroy(tc->t_cpath->cp_conn);
}

Project: linux
File: tcp.c

static void rds_tcp_exit(void)
{
	rds_tcp_set_unloading();
	synchronize_rcu();
	rds_info_deregister_func(RDS_INFO_TCP_SOCKETS, rds_tcp_tc_info);
#if IS_ENABLED(CONFIG_IPV6)
	rds_info_deregister_func(RDS6_INFO_TCP_SOCKETS, rds6_tcp_tc_info);
#endif
	unregister_pernet_device(&rds_tcp_net_ops);
	rds_tcp_destroy_conns();
	rds_trans_unregister(&rds_tcp_transport);
	rds_tcp_recv_exit();
	kmem_cache_destroy(rds_tcp_conn_slab);
}

Project: linux
File: tcp.c

static void __net_exit rds_tcp_exit_net(struct net *net)
{
	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);

	rds_tcp_kill_sock(net);

	if (rtn->rds_tcp_sysctl)
		unregister_net_sysctl_table(rtn->rds_tcp_sysctl);

	if (net != &init_net)
		kfree(rtn->ctl_table);
}

Project: linux
File: tcp.c

static __net_init int rds_tcp_init_net(struct net *net)
{
	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
	struct ctl_table *tbl;
	int err = 0;

	memset(rtn, 0, sizeof(*rtn));

	/* {snd, rcv}buf_size default to 0, which implies we let the
	 * stack pick the value, and permit auto-tuning of buffer size.
	 */
	if (net == &init_net) {
		tbl = rds_tcp_sysctl_table;
	} else {
		tbl = kmemdup(rds_tcp_sysctl_table,
			      sizeof(rds_tcp_sysctl_table), GFP_KERNEL);
		if (!tbl) {
			pr_warn("could not set allocate syctl table\n");
			return -ENOMEM;
		}
		rtn->ctl_table = tbl;
	}
	tbl[RDS_TCP_SNDBUF].data = &rtn->sndbuf_size;
	tbl[RDS_TCP_RCVBUF].data = &rtn->rcvbuf_size;
	rtn->rds_tcp_sysctl = register_net_sysctl(net, "net/rds/tcp", tbl);
	if (!rtn->rds_tcp_sysctl) {
		pr_warn("could not register sysctl\n");
		err = -ENOMEM;
		goto fail;
	}

#if IS_ENABLED(CONFIG_IPV6)
	rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net, true);
#else
	rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net, false);
#endif
	if (!rtn->rds_tcp_listen_sock) {
		pr_warn("could not set up IPv6 listen sock\n");

#if IS_ENABLED(CONFIG_IPV6)
		/* Try IPv4 as some systems disable IPv6 */
		rtn->rds_tcp_listen_sock = rds_tcp_listen_init(net, false);
		if (!rtn->rds_tcp_listen_sock) {
#endif
			unregister_net_sysctl_table(rtn->rds_tcp_sysctl);
			rtn->rds_tcp_sysctl = NULL;
			err = -EAFNOSUPPORT;
			goto fail;
#if IS_ENABLED(CONFIG_IPV6)
		}
#endif
	}
	INIT_WORK(&rtn->rds_tcp_accept_w, rds_tcp_accept_worker);
	return 0;

fail:
	if (net != &init_net)
		kfree(tbl);
	return err;
}

Project: linux
File: tcp.c

static int rds_tcp_laddr_check(struct net *net, const struct in6_addr *addr,
			       __u32 scope_id)
{
	struct net_device *dev = NULL;
#if IS_ENABLED(CONFIG_IPV6)
	int ret;
#endif

	if (ipv6_addr_v4mapped(addr)) {
		if (inet_addr_type(net, addr->s6_addr32[3]) == RTN_LOCAL)
			return 0;
		return -EADDRNOTAVAIL;
	}

	/* If the scope_id is specified, check only those addresses
	 * hosted on the specified interface.
	 */
	if (scope_id != 0) {
		rcu_read_lock();
		dev = dev_get_by_index_rcu(net, scope_id);
		/* scope_id is not valid... */
		if (!dev) {
			rcu_read_unlock();
			return -EADDRNOTAVAIL;
		}
		rcu_read_unlock();
	}
#if IS_ENABLED(CONFIG_IPV6)
	ret = ipv6_chk_addr(net, addr, dev, 0);
	if (ret)
		return 0;
#endif
	return -EADDRNOTAVAIL;
}

Project: linux
File: tcp.c

void *rds_tcp_listen_sock_def_readable(struct net *net)
{
	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
	struct socket *lsock = rtn->rds_tcp_listen_sock;

	if (!lsock)
		return NULL;

	return lsock->sk->sk_user_data;
}

Project: linux
File: tcp.c

void rds_tcp_nonagle(struct socket *sock)
{
	int val = 1;

	kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (void *)&val,
			      sizeof(val));
}

Project: linux
File: tcp.c

void rds_tcp_reset_callbacks(struct socket *sock,
			     struct rds_conn_path *cp)
{
	struct rds_tcp_connection *tc = cp->cp_transport_data;
	struct socket *osock = tc->t_sock;

	if (!osock)
		goto newsock;

	/* Need to resolve a duelling SYN between peers.
	 * We have an outstanding SYN to this peer, which may
	 * potentially have transitioned to the RDS_CONN_UP state,
	 * so we must quiesce any send threads before resetting
	 * cp_transport_data. We quiesce these threads by setting
	 * cp_state to something other than RDS_CONN_UP, and then
	 * waiting for any existing threads in rds_send_xmit to
	 * complete release_in_xmit(). (Subsequent threads entering
	 * rds_send_xmit() will bail on !rds_conn_up().
	 *
	 * However an incoming syn-ack at this point would end up
	 * marking the conn as RDS_CONN_UP, and would again permit
	 * rds_send_xmi() threads through, so ideally we would
	 * synchronize on RDS_CONN_UP after lock_sock(), but cannot
	 * do that: waiting on !RDS_IN_XMIT after lock_sock() may
	 * end up deadlocking with tcp_sendmsg(), and the RDS_IN_XMIT
	 * would not get set. As a result, we set c_state to
	 * RDS_CONN_RESETTTING, to ensure that rds_tcp_state_change
	 * cannot mark rds_conn_path_up() in the window before lock_sock()
	 */
	atomic_set(&cp->cp_state, RDS_CONN_RESETTING);
	wait_event(cp->cp_waitq, !test_bit(RDS_IN_XMIT, &cp->cp_flags));
	lock_sock(osock->sk);
	/* reset receive side state for rds_tcp_data_recv() for osock  */
	cancel_delayed_work_sync(&cp->cp_send_w);
	cancel_delayed_work_sync(&cp->cp_recv_w);
	if (tc->t_tinc) {
		rds_inc_put(&tc->t_tinc->ti_inc);
		tc->t_tinc = NULL;
	}
	tc->t_tinc_hdr_rem = sizeof(struct rds_header);
	tc->t_tinc_data_rem = 0;
	rds_tcp_restore_callbacks(osock, tc);
	release_sock(osock->sk);
	sock_release(osock);
newsock:
	rds_send_path_reset(cp);
	lock_sock(sock->sk);
	rds_tcp_set_callbacks(sock, cp);
	release_sock(sock->sk);
}

Project: linux
File: tcp.c

void rds_tcp_restore_callbacks(struct socket *sock,
			       struct rds_tcp_connection *tc)
{
	rdsdebug("restoring sock %p callbacks from tc %p\n", sock, tc);
	write_lock_bh(&sock->sk->sk_callback_lock);

	/* done under the callback_lock to serialize with write_space */
	spin_lock(&rds_tcp_tc_list_lock);
	list_del_init(&tc->t_list_item);
#if IS_ENABLED(CONFIG_IPV6)
	rds6_tcp_tc_count--;
#endif
	if (!tc->t_cpath->cp_conn->c_isv6)
		rds_tcp_tc_count--;
	spin_unlock(&rds_tcp_tc_list_lock);

	tc->t_sock = NULL;

	sock->sk->sk_write_space = tc->t_orig_write_space;
	sock->sk->sk_data_ready = tc->t_orig_data_ready;
	sock->sk->sk_state_change = tc->t_orig_state_change;
	sock->sk->sk_user_data = NULL;

	write_unlock_bh(&sock->sk->sk_callback_lock);
}

Project: linux
File: tcp.c

void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp)
{
	struct rds_tcp_connection *tc = cp->cp_transport_data;

	rdsdebug("setting sock %p callbacks to tc %p\n", sock, tc);
	write_lock_bh(&sock->sk->sk_callback_lock);

	/* done under the callback_lock to serialize with write_space */
	spin_lock(&rds_tcp_tc_list_lock);
	list_add_tail(&tc->t_list_item, &rds_tcp_tc_list);
#if IS_ENABLED(CONFIG_IPV6)
	rds6_tcp_tc_count++;
#endif
	if (!tc->t_cpath->cp_conn->c_isv6)
		rds_tcp_tc_count++;
	spin_unlock(&rds_tcp_tc_list_lock);

	/* accepted sockets need our listen data ready undone */
	if (sock->sk->sk_data_ready == rds_tcp_listen_data_ready)
		sock->sk->sk_data_ready = sock->sk->sk_user_data;

	tc->t_sock = sock;
	tc->t_cpath = cp;
	tc->t_orig_data_ready = sock->sk->sk_data_ready;
	tc->t_orig_write_space = sock->sk->sk_write_space;
	tc->t_orig_state_change = sock->sk->sk_state_change;

	sock->sk->sk_user_data = cp;
	sock->sk->sk_data_ready = rds_tcp_data_ready;
	sock->sk->sk_write_space = rds_tcp_write_space;
	sock->sk->sk_state_change = rds_tcp_state_change;

	write_unlock_bh(&sock->sk->sk_callback_lock);
}

Project: linux
File: tcp.c

static void rds_tcp_set_unloading(void)
{
	atomic_set(&rds_tcp_unloading, 1);
}

Project: linux
File: tcp.c

u32 rds_tcp_snd_una(struct rds_tcp_connection *tc)
{
	return tcp_sk(tc->t_sock->sk)->snd_una;
}

Project: linux
File: tcp.c

static void rds_tcp_sysctl_reset(struct net *net)
{
	struct rds_tcp_connection *tc, *_tc;

	spin_lock_irq(&rds_tcp_conn_lock);
	list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
		struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);

		if (net != c_net || !tc->t_sock)
			continue;

		/* reconnect with new parameters */
		rds_conn_path_drop(tc->t_cpath, false);
	}
	spin_unlock_irq(&rds_tcp_conn_lock);
}

Project: linux
File: tcp.c

static void rds_tcp_tc_info(struct socket *rds_sock, unsigned int len,
			    struct rds_info_iterator *iter,
			    struct rds_info_lengths *lens)
{
	struct rds_info_tcp_socket tsinfo;
	struct rds_tcp_connection *tc;
	unsigned long flags;

	spin_lock_irqsave(&rds_tcp_tc_list_lock, flags);

	if (len / sizeof(tsinfo) < rds_tcp_tc_count)
		goto out;

	list_for_each_entry(tc, &rds_tcp_tc_list, t_list_item) {
		struct inet_sock *inet = inet_sk(tc->t_sock->sk);

		if (tc->t_cpath->cp_conn->c_isv6)
			continue;

		tsinfo.local_addr = inet->inet_saddr;
		tsinfo.local_port = inet->inet_sport;
		tsinfo.peer_addr = inet->inet_daddr;
		tsinfo.peer_port = inet->inet_dport;

		tsinfo.hdr_rem = tc->t_tinc_hdr_rem;
		tsinfo.data_rem = tc->t_tinc_data_rem;
		tsinfo.last_sent_nxt = tc->t_last_sent_nxt;
		tsinfo.last_expected_una = tc->t_last_expected_una;
		tsinfo.last_seen_una = tc->t_last_seen_una;
		tsinfo.tos = tc->t_cpath->cp_conn->c_tos;

		rds_info_copy(iter, &tsinfo, sizeof(tsinfo));
	}

out:
	lens->nr = rds_tcp_tc_count;
	lens->each = sizeof(tsinfo);

	spin_unlock_irqrestore(&rds_tcp_tc_list_lock, flags);
}

Project: linux
File: tcp.c

void rds_tcp_tune(struct socket *sock)
{
	struct sock *sk = sock->sk;
	struct net *net = sock_net(sk);
	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);

	rds_tcp_nonagle(sock);
	lock_sock(sk);
	if (rtn->sndbuf_size > 0) {
		sk->sk_sndbuf = rtn->sndbuf_size;
		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
	}
	if (rtn->rcvbuf_size > 0) {
		sk->sk_sndbuf = rtn->rcvbuf_size;
		sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
	}
	release_sock(sk);
}

Project: linux
File: tcp.c

u32 rds_tcp_write_seq(struct rds_tcp_connection *tc)
{
	/* seq# of the last byte of data in tcp send buffer */
	return tcp_sk(tc->t_sock->sk)->write_seq;
}