linux-toradex.git/net/l2tp, branch v4.4.151

l2tp: use sk_dst_check() to avoid race on sk->sk_dst_cache

2018-08-22T05:48:35+00:00

[ Upstream commit 6d37fa49da1e8db8fb1995be22ac837ca41ac8a8 ]

In l2tp code, if it is a L2TP_UDP_ENCAP tunnel, tunnel->sk points to a
UDP socket. User could call sendmsg() on both this tunnel and the UDP
socket itself concurrently. As l2tp_xmit_skb() holds socket lock and call
__sk_dst_check() to refresh sk->sk_dst_cache, while udpv6_sendmsg() is
lockless and call sk_dst_check() to refresh sk->sk_dst_cache, there
could be a race and cause the dst cache to be freed multiple times.
So we fix l2tp side code to always call sk_dst_check() to garantee
xchg() is called when refreshing sk->sk_dst_cache to avoid race
conditions.

Syzkaller reported stack trace:
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in atomic_fetch_add_unless include/linux/atomic.h:575 [inline]
BUG: KASAN: use-after-free in atomic_add_unless include/linux/atomic.h:597 [inline]
BUG: KASAN: use-after-free in dst_hold_safe include/net/dst.h:308 [inline]
BUG: KASAN: use-after-free in ip6_hold_safe+0xe6/0x670 net/ipv6/route.c:1029
Read of size 4 at addr ffff8801aea9a880 by task syz-executor129/4829

CPU: 0 PID: 4829 Comm: syz-executor129 Not tainted 4.18.0-rc7-next-20180802+ #30
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
 atomic_fetch_add_unless include/linux/atomic.h:575 [inline]
 atomic_add_unless include/linux/atomic.h:597 [inline]
 dst_hold_safe include/net/dst.h:308 [inline]
 ip6_hold_safe+0xe6/0x670 net/ipv6/route.c:1029
 rt6_get_pcpu_route net/ipv6/route.c:1249 [inline]
 ip6_pol_route+0x354/0xd20 net/ipv6/route.c:1922
 ip6_pol_route_output+0x54/0x70 net/ipv6/route.c:2098
 fib6_rule_lookup+0x283/0x890 net/ipv6/fib6_rules.c:122
 ip6_route_output_flags+0x2c5/0x350 net/ipv6/route.c:2126
 ip6_dst_lookup_tail+0x1278/0x1da0 net/ipv6/ip6_output.c:978
 ip6_dst_lookup_flow+0xc8/0x270 net/ipv6/ip6_output.c:1079
 ip6_sk_dst_lookup_flow+0x5ed/0xc50 net/ipv6/ip6_output.c:1117
 udpv6_sendmsg+0x2163/0x36b0 net/ipv6/udp.c:1354
 inet_sendmsg+0x1a1/0x690 net/ipv4/af_inet.c:798
 sock_sendmsg_nosec net/socket.c:622 [inline]
 sock_sendmsg+0xd5/0x120 net/socket.c:632
 ___sys_sendmsg+0x51d/0x930 net/socket.c:2115
 __sys_sendmmsg+0x240/0x6f0 net/socket.c:2210
 __do_sys_sendmmsg net/socket.c:2239 [inline]
 __se_sys_sendmmsg net/socket.c:2236 [inline]
 __x64_sys_sendmmsg+0x9d/0x100 net/socket.c:2236
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446a29
Code: e8 ac b8 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4de5532db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000006dcc38 RCX: 0000000000446a29
RDX: 00000000000000b8 RSI: 0000000020001b00 RDI: 0000000000000003
RBP: 00000000006dcc30 R08: 00007f4de5533700 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dcc3c
R13: 00007ffe2b830fdf R14: 00007f4de55339c0 R15: 0000000000000001

Fixes: 71b1391a4128 ("l2tp: ensure sk->dst is still valid")
Reported-by: syzbot+05f840f3b04f211bad55@syzkaller.appspotmail.com
Signed-off-by: Wei Wang 
Signed-off-by: Martin KaFai Lau 
Cc: Guillaume Nault 
Cc: David Ahern 
Cc: Cong Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

l2tp: revert "l2tp: fix missing print session offset info"

2018-05-26T06:48:50+00:00

commit de3b58bc359a861d5132300f53f95e83f71954b3 upstream.

Revert commit 820da5357572 ("l2tp: fix missing print session offset
info").  The peer_offset parameter is removed.

Signed-off-by: James Chapman 
Signed-off-by: David S. Miller 
Cc: Guillaume Nault 
Signed-off-by: Greg Kroah-Hartman

l2tp: check sockaddr length in pppol2tp_connect()

2018-04-29T05:50:04+00:00

[ Upstream commit eb1c28c05894a4b1f6b56c5bf072205e64cfa280 ]

Check sockaddr_len before dereferencing sp->sa_protocol, to ensure that
it actually points to valid data.

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Reported-by: syzbot+a70ac890b23b1bf29f5c@syzkaller.appspotmail.com
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

l2tp: fix missing print session offset info

2018-04-13T17:50:12+00:00

[ Upstream commit 820da5357572715c6235ba3b3daa2d5b43a1198f ]

Report offset parameter in L2TP_CMD_SESSION_GET command if
it has been configured by userspace

Fixes: 309795f4bec ("l2tp: Add netlink control API for L2TP")
Reported-by: Jianlin Shi 
Signed-off-by: Hangbin Liu 
Signed-off-by: Lorenzo Bianconi 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

l2tp: do not accept arbitrary sockets

2018-03-31T16:12:33+00:00

[ Upstream commit 17cfe79a65f98abe535261856c5aef14f306dff7 ]

syzkaller found an issue caused by lack of sufficient checks
in l2tp_tunnel_create()

RAW sockets can not be considered as UDP ones for instance.

In another patch, we shall replace all pr_err() by less intrusive
pr_debug() so that syzkaller can find other bugs faster.
Acked-by: Guillaume Nault 
Acked-by: James Chapman 

==================================================================
BUG: KASAN: slab-out-of-bounds in setup_udp_tunnel_sock+0x3ee/0x5f0 net/ipv4/udp_tunnel.c:69
dst_release: dst:00000000d53d0d0f refcnt:-1
Write of size 1 at addr ffff8801d013b798 by task syz-executor3/6242

CPU: 1 PID: 6242 Comm: syz-executor3 Not tainted 4.16.0-rc2+ #253
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:435
 setup_udp_tunnel_sock+0x3ee/0x5f0 net/ipv4/udp_tunnel.c:69
 l2tp_tunnel_create+0x1354/0x17f0 net/l2tp/l2tp_core.c:1596
 pppol2tp_connect+0x14b1/0x1dd0 net/l2tp/l2tp_ppp.c:707
 SYSC_connect+0x213/0x4a0 net/socket.c:1640
 SyS_connect+0x24/0x30 net/socket.c:1621
 do_syscall_64+0x280/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

l2tp: cleanup l2tp_tunnel_delete calls

2017-12-20T09:04:59+00:00

[ Upstream commit 4dc12ffeaeac939097a3f55c881d3dc3523dff0c ]

l2tp_tunnel_delete does not return anything since commit 62b982eeb458
("l2tp: fix race condition in l2tp_tunnel_delete").  But call sites of
l2tp_tunnel_delete still do casts to void to avoid unused return value
warnings.

Kill these now useless casts.

Signed-off-by: Jiri Slaby 
Cc: Sabrina Dubroca 
Cc: Guillaume Nault 
Cc: David S. Miller 
Cc: netdev@vger.kernel.org
Acked-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

l2tp: check ps->sock before running pppol2tp_session_ioctl()

2017-11-18T10:11:05+00:00

[ Upstream commit 5903f594935a3841137c86b9d5b75143a5b7121c ]

When pppol2tp_session_ioctl() is called by pppol2tp_tunnel_ioctl(),
the session may be unconnected. That is, it was created by
pppol2tp_session_create() and hasn't been connected with
pppol2tp_connect(). In this case, ps->sock is NULL, so we need to check
for this case in order to avoid dereferencing a NULL pointer.

Fixes: 309795f4bec2 ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

l2tp: fix race condition in l2tp_tunnel_delete

2017-10-21T15:09:03+00:00

[ Upstream commit 62b982eeb4589b2e6d7c01a90590e3a4c2b2ca19 ]

If we try to delete the same tunnel twice, the first delete operation
does a lookup (l2tp_tunnel_get), finds the tunnel, calls
l2tp_tunnel_delete, which queues it for deletion by
l2tp_tunnel_del_work.

The second delete operation also finds the tunnel and calls
l2tp_tunnel_delete. If the workqueue has already fired and started
running l2tp_tunnel_del_work, then l2tp_tunnel_delete will queue the
same tunnel a second time, and try to free the socket again.

Add a dead flag to prevent firing the workqueue twice. Then we can
remove the check of queue_work's result that was meant to prevent that
race but doesn't.

Reproducer:

    ip l2tp add tunnel tunnel_id 3000 peer_tunnel_id 4000 local 192.168.0.2 remote 192.168.0.1 encap udp udp_sport 5000 udp_dport 6000
    ip l2tp add session name l2tp1 tunnel_id 3000 session_id 1000 peer_session_id 2000
    ip link set l2tp1 up
    ip l2tp del tunnel tunnel_id 3000
    ip l2tp del tunnel tunnel_id 3000

Fixes: f8ccac0e4493 ("l2tp: put tunnel socket release on a workqueue")
Reported-by: Jianlin Shi 
Signed-off-by: Sabrina Dubroca 
Acked-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

l2tp: Avoid schedule while atomic in exit_net

2017-10-21T15:09:03+00:00

[ Upstream commit 12d656af4e3d2781b9b9f52538593e1717e7c979 ]

While destroying a network namespace that contains a L2TP tunnel a
"BUG: scheduling while atomic" can be observed.

Enabling lockdep shows that this is happening because l2tp_exit_net()
is calling l2tp_tunnel_closeall() (via l2tp_tunnel_delete()) from
within an RCU critical section.

l2tp_exit_net() takes rcu_read_lock_bh()
  << list_for_each_entry_rcu() >>
  l2tp_tunnel_delete()
    l2tp_tunnel_closeall()
      __l2tp_session_unhash()
        synchronize_rcu() << Illegal inside RCU critical section >>

BUG: sleeping function called from invalid context
in_atomic(): 1, irqs_disabled(): 0, pid: 86, name: kworker/u16:2
INFO: lockdep is turned off.
CPU: 2 PID: 86 Comm: kworker/u16:2 Tainted: G        W  O    4.4.6-at1 #2
Hardware name: Xen HVM domU, BIOS 4.6.1-xs125300 05/09/2016
Workqueue: netns cleanup_net
 0000000000000000 ffff880202417b90 ffffffff812b0013 ffff880202410ac0
 ffffffff81870de8 ffff880202417bb8 ffffffff8107aee8 ffffffff81870de8
 0000000000000c51 0000000000000000 ffff880202417be0 ffffffff8107b024
Call Trace:
 [] dump_stack+0x85/0xc2
 [] ___might_sleep+0x148/0x240
 [] __might_sleep+0x44/0x80
 [] synchronize_sched+0x2d/0xe0
 [] ? trace_hardirqs_on+0xd/0x10
 [] ? __local_bh_enable_ip+0x6b/0xc0
 [] ? _raw_spin_unlock_bh+0x30/0x40
 [] __l2tp_session_unhash+0x172/0x220
 [] ? __l2tp_session_unhash+0x87/0x220
 [] l2tp_tunnel_closeall+0x9b/0x140
 [] l2tp_tunnel_delete+0x14/0x60
 [] l2tp_exit_net+0x110/0x270
 [] ? l2tp_exit_net+0x9c/0x270
 [] ops_exit_list.isra.6+0x33/0x60
 [] cleanup_net+0x1b6/0x280
 ...

This bug can easily be reproduced with a few steps:

 $ sudo unshare -n bash  # Create a shell in a new namespace
 # ip link set lo up
 # ip addr add 127.0.0.1 dev lo
 # ip l2tp add tunnel remote 127.0.0.1 local 127.0.0.1 tunnel_id 1 \
    peer_tunnel_id 1 udp_sport 50000 udp_dport 50000
 # ip l2tp add session name foo tunnel_id 1 session_id 1 \
    peer_session_id 1
 # ip link set foo up
 # exit  # Exit the shell, in turn exiting the namespace
 $ dmesg
 ...
 [942121.089216] BUG: scheduling while atomic: kworker/u16:3/13872/0x00000200
 ...

To fix this, move the call to l2tp_tunnel_closeall() out of the RCU
critical section, and instead call it from l2tp_tunnel_del_work(), which
is running from the l2tp_wq workqueue.

Fixes: 2b551c6e7d5b ("l2tp: close sessions before initiating tunnel delete")
Signed-off-by: Ridge Kennedy 
Acked-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

l2tp: fix PPP pseudo-wire auto-loading

2017-05-03T04:19:52+00:00

[ Upstream commit 249ee819e24c180909f43c1173c8ef6724d21faf ]

PPP pseudo-wire type is 7 (11 is L2TP_PWTYPE_IP).

Fixes: f1f39f911027 ("l2tp: auto load type modules")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman