linux-stable.git/drivers/net/ppp, branch v3.16.67

pppoe: fix reception of frames with no mac header

2018-12-16T22:09:19+00:00

commit 8540827ebac6b654ab2f69c8fbce9e4fbd6304a0 upstream.

pppoe_rcv() needs to look back at the Ethernet header in order to
lookup the PPPoE session. Therefore we need to ensure that the mac
header is big enough to contain an Ethernet header. Otherwise
eth_hdr(skb)->h_source might access invalid data.

==================================================================
BUG: KMSAN: uninit-value in __get_item drivers/net/ppp/pppoe.c:172 [inline]
BUG: KMSAN: uninit-value in get_item drivers/net/ppp/pppoe.c:236 [inline]
BUG: KMSAN: uninit-value in pppoe_rcv+0xcef/0x10e0 drivers/net/ppp/pppoe.c:450
CPU: 0 PID: 4543 Comm: syz-executor355 Not tainted 4.16.0+ #87
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+0x185/0x1d0 lib/dump_stack.c:53
 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067
 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
 __get_item drivers/net/ppp/pppoe.c:172 [inline]
 get_item drivers/net/ppp/pppoe.c:236 [inline]
 pppoe_rcv+0xcef/0x10e0 drivers/net/ppp/pppoe.c:450
 __netif_receive_skb_core+0x47df/0x4a90 net/core/dev.c:4562
 __netif_receive_skb net/core/dev.c:4627 [inline]
 netif_receive_skb_internal+0x49d/0x630 net/core/dev.c:4701
 netif_receive_skb+0x230/0x240 net/core/dev.c:4725
 tun_rx_batched drivers/net/tun.c:1555 [inline]
 tun_get_user+0x740f/0x7c60 drivers/net/tun.c:1962
 tun_chr_write_iter+0x1d4/0x330 drivers/net/tun.c:1990
 call_write_iter include/linux/fs.h:1782 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x7fb/0x9f0 fs/read_write.c:482
 vfs_write+0x463/0x8d0 fs/read_write.c:544
 SYSC_write+0x172/0x360 fs/read_write.c:589
 SyS_write+0x55/0x80 fs/read_write.c:581
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
RIP: 0033:0x4447c9
RSP: 002b:00007fff64c8fc28 EFLAGS: 00000297 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004447c9
RDX: 000000000000fd87 RSI: 0000000020000600 RDI: 0000000000000004
RBP: 00000000006cf018 R08: 00007fff64c8fda8 R09: 00007fff00006bda
R10: 0000000000005fe7 R11: 0000000000000297 R12: 00000000004020d0
R13: 0000000000402160 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314
 kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321
 slab_post_alloc_hook mm/slab.h:445 [inline]
 slab_alloc_node mm/slub.c:2737 [inline]
 __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369
 __kmalloc_reserve net/core/skbuff.c:138 [inline]
 __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206
 alloc_skb include/linux/skbuff.h:984 [inline]
 alloc_skb_with_frags+0x1d4/0xb20 net/core/skbuff.c:5234
 sock_alloc_send_pskb+0xb56/0x1190 net/core/sock.c:2085
 tun_alloc_skb drivers/net/tun.c:1532 [inline]
 tun_get_user+0x2242/0x7c60 drivers/net/tun.c:1829
 tun_chr_write_iter+0x1d4/0x330 drivers/net/tun.c:1990
 call_write_iter include/linux/fs.h:1782 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x7fb/0x9f0 fs/read_write.c:482
 vfs_write+0x463/0x8d0 fs/read_write.c:544
 SYSC_write+0x172/0x360 fs/read_write.c:589
 SyS_write+0x55/0x80 fs/read_write.c:581
 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x3d/0xa2
==================================================================

Fixes: 224cf5ad14c0 ("ppp: Move the PPP drivers")
Reported-by: syzbot+f5f6080811c849739212@syzkaller.appspotmail.com
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

ppp: remove the PPPIOCDETACH ioctl

2018-10-21T07:46:19+00:00

commit af8d3c7c001ae7df1ed2b2715f058113efc86187 upstream.

The PPPIOCDETACH ioctl effectively tries to "close" the given ppp file
before f_count has reached 0, which is fundamentally a bad idea.  It
does check 'f_count < 2', which excludes concurrent operations on the
file since they would only be possible with a shared fd table, in which
case each fdget() would take a file reference.  However, it fails to
account for the fact that even with 'f_count == 1' the file can still be
linked into epoll instances.  As reported by syzbot, this can trivially
be used to cause a use-after-free.

Yet, the only known user of PPPIOCDETACH is pppd versions older than
ppp-2.4.2, which was released almost 15 years ago (November 2003).
Also, PPPIOCDETACH apparently stopped working reliably at around the
same time, when the f_count check was added to the kernel, e.g. see
https://lkml.org/lkml/2002/12/31/83.  Also, the current 'f_count < 2'
check makes PPPIOCDETACH only work in single-threaded applications; it
always fails if called from a multithreaded application.

All pppd versions released in the last 15 years just close() the file
descriptor instead.

Therefore, instead of hacking around this bug by exporting epoll
internals to modules, and probably missing other related bugs, just
remove the PPPIOCDETACH ioctl and see if anyone actually notices.  Leave
a stub in place that prints a one-time warning and returns EINVAL.

Reported-by: syzbot+16363c99d4134717c05b@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Biggers 
Acked-by: Paul Mackerras 
Reviewed-by: Guillaume Nault 
Tested-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

ppp: unlock all_ppp_mutex before registering device

2018-10-21T07:46:19+00:00

commit 0171c41835591e9aa2e384b703ef9a6ae367c610 upstream.

ppp_dev_uninit(), which is the .ndo_uninit() handler of PPP devices,
needs to lock pn->all_ppp_mutex. Therefore we mustn't call
register_netdevice() with pn->all_ppp_mutex already locked, or we'd
deadlock in case register_netdevice() fails and calls .ndo_uninit().

Fortunately, we can unlock pn->all_ppp_mutex before calling
register_netdevice(). This lock protects pn->units_idr, which isn't
used in the device registration process.

However, keeping pn->all_ppp_mutex locked during device registration
did ensure that no device in transient state would be published in
pn->units_idr. In practice, unlocking it before calling
register_netdevice() doesn't change this property: ppp_unit_register()
is called with 'ppp_mutex' locked and all searches done in
pn->units_idr hold this lock too.

Fixes: 8cb775bc0a34 ("ppp: fix device unregistration upon netns deletion")
Reported-and-tested-by: syzbot+367889b9c9e279219175@syzkaller.appspotmail.com
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

ppp: Fix null pointer dereference on registration failure

2018-10-21T07:46:19+00:00

register_netdevice() will call the device's ndo_uninit operation if
registration fails after it calls the ndo_init operation.  However
ppp_dev_uninit() uses ppp->ppp_net which is currently not set until
after register_netdevice() returns.

This was fixed upstream as part of commit 96d934c70db6 "ppp: add
rtnetlink device creation support".

Signed-off-by: Ben Hutchings

ppp: fix race in ppp device destruction

2018-10-21T07:46:18+00:00

commit 6151b8b37b119e8e3a8401b080d532520c95faf4 upstream.

ppp_release() tries to ensure that netdevices are unregistered before
decrementing the unit refcount and running ppp_destroy_interface().

This is all fine as long as the the device is unregistered by
ppp_release(): the unregister_netdevice() call, followed by
rtnl_unlock(), guarantee that the unregistration process completes
before rtnl_unlock() returns.

However, the device may be unregistered by other means (like
ppp_nl_dellink()). If this happens right before ppp_release() calling
rtnl_lock(), then ppp_release() has to wait for the concurrent
unregistration code to release the lock.
But rtnl_unlock() releases the lock before completing the device
unregistration process. This allows ppp_release() to proceed and
eventually call ppp_destroy_interface() before the unregistration
process completes. Calling free_netdev() on this partially unregistered
device will BUG():

 ------------[ cut here ]------------
 kernel BUG at net/core/dev.c:8141!
 invalid opcode: 0000 [#1] SMP

 CPU: 1 PID: 1557 Comm: pppd Not tainted 4.14.0-rc2+ #4
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc26 04/01/2014

 Call Trace:
  ppp_destroy_interface+0xd8/0xe0 [ppp_generic]
  ppp_disconnect_channel+0xda/0x110 [ppp_generic]
  ppp_unregister_channel+0x5e/0x110 [ppp_generic]
  pppox_unbind_sock+0x23/0x30 [pppox]
  pppoe_connect+0x130/0x440 [pppoe]
  SYSC_connect+0x98/0x110
  ? do_fcntl+0x2c0/0x5d0
  SyS_connect+0xe/0x10
  entry_SYSCALL_64_fastpath+0x1a/0xa5

 RIP: free_netdev+0x107/0x110 RSP: ffffc28a40573d88
 ---[ end trace ed294ff0cc40eeff ]---

We could set the ->needs_free_netdev flag on PPP devices and move the
ppp_destroy_interface() logic in the ->priv_destructor() callback. But
that'd be quite intrusive as we'd first need to unlink from the other
channels and units that depend on the device (the ones that used the
PPPIOCCONNECT and PPPIOCATTACH ioctls).

Instead, we can just let the netdevice hold a reference on its
ppp_file. This reference is dropped in ->priv_destructor(), at the very
end of the unregistration process, so that neither ppp_release() nor
ppp_disconnect_channel() can call ppp_destroy_interface() in the interim.

Reported-by: Beniamino Galvani 
Fixes: 8cb775bc0a34 ("ppp: fix device unregistration upon netns deletion")
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: Set net_device::destructor instead of
 priv_destructor, and call ppp_dev_priv_destructor() if register_netdevice()
 fails after call ppp_dev_init().]
Signed-off-by: Ben Hutchings

ppp: fix lockdep splat in ppp_dev_uninit()

2018-10-21T07:46:18+00:00

commit 58a89ecaca53736aa465170530acea4f8be34ab4 upstream.

ppp_dev_uninit() locks all_ppp_mutex while under rtnl mutex protection.
ppp_create_interface() must then lock these mutexes in that same order
to avoid possible deadlock.

[  120.880011] ======================================================
[  120.880011] [ INFO: possible circular locking dependency detected ]
[  120.880011] 4.2.0 #1 Not tainted
[  120.880011] -------------------------------------------------------
[  120.880011] ppp-apitest/15827 is trying to acquire lock:
[  120.880011]  (&pn->all_ppp_mutex){+.+.+.}, at: [] ppp_dev_uninit+0x64/0xb0 [ppp_generic]
[  120.880011]
[  120.880011] but task is already holding lock:
[  120.880011]  (rtnl_mutex){+.+.+.}, at: [] rtnl_lock+0x12/0x14
[  120.880011]
[  120.880011] which lock already depends on the new lock.
[  120.880011]
[  120.880011]
[  120.880011] the existing dependency chain (in reverse order) is:
[  120.880011]
[  120.880011] -> #1 (rtnl_mutex){+.+.+.}:
[  120.880011]        [] lock_acquire+0xcf/0x10e
[  120.880011]        [] mutex_lock_nested+0x56/0x341
[  120.880011]        [] rtnl_lock+0x12/0x14
[  120.880011]        [] register_netdev+0x11/0x27
[  120.880011]        [] ppp_ioctl+0x289/0xc98 [ppp_generic]
[  120.880011]        [] do_vfs_ioctl+0x4ea/0x532
[  120.880011]        [] SyS_ioctl+0x4e/0x7d
[  120.880011]        [] entry_SYSCALL_64_fastpath+0x12/0x6f
[  120.880011]
[  120.880011] -> #0 (&pn->all_ppp_mutex){+.+.+.}:
[  120.880011]        [] __lock_acquire+0xb07/0xe76
[  120.880011]        [] lock_acquire+0xcf/0x10e
[  120.880011]        [] mutex_lock_nested+0x56/0x341
[  120.880011]        [] ppp_dev_uninit+0x64/0xb0 [ppp_generic]
[  120.880011]        [] rollback_registered_many+0x19e/0x252
[  120.880011]        [] rollback_registered+0x29/0x38
[  120.880011]        [] unregister_netdevice_queue+0x6a/0x77
[  120.880011]        [] ppp_release+0x42/0x79 [ppp_generic]
[  120.880011]        [] __fput+0xec/0x192
[  120.880011]        [] ____fput+0x9/0xb
[  120.880011]        [] task_work_run+0x66/0x80
[  120.880011]        [] prepare_exit_to_usermode+0x8c/0xa7
[  120.880011]        [] syscall_return_slowpath+0xe4/0x104
[  120.880011]        [] int_ret_from_sys_call+0x25/0x9f
[  120.880011]
[  120.880011] other info that might help us debug this:
[  120.880011]
[  120.880011]  Possible unsafe locking scenario:
[  120.880011]
[  120.880011]        CPU0                    CPU1
[  120.880011]        ----                    ----
[  120.880011]   lock(rtnl_mutex);
[  120.880011]                                lock(&pn->all_ppp_mutex);
[  120.880011]                                lock(rtnl_mutex);
[  120.880011]   lock(&pn->all_ppp_mutex);
[  120.880011]
[  120.880011]  *** DEADLOCK ***

Fixes: 8cb775bc0a34 ("ppp: fix device unregistration upon netns deletion")
Reported-by: Sedat Dilek 
Tested-by: Sedat Dilek 
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

ppp: fix device unregistration upon netns deletion

2018-10-21T07:46:18+00:00

commit 8cb775bc0a34dc596837e7da03fd22c747be618b upstream.

PPP devices may get automatically unregistered when their network
namespace is getting removed. This happens if the ppp control plane
daemon (e.g. pppd) exits while it is the last user of this namespace.

This leads to several races:

  * ppp_exit_net() may destroy the per namespace idr (pn->units_idr)
    before all file descriptors were released. Successive ppp_release()
    calls may then cleanup PPP devices with ppp_shutdown_interface() and
    try to use the already destroyed idr.

  * Automatic device unregistration may also happen before the
    ppp_release() call for that device gets executed. Once called on
    the file owning the device, ppp_release() will then clean it up and
    try to unregister it a second time.

To fix these issues, operations defined in ppp_shutdown_interface() are
moved to the PPP device's ndo_uninit() callback. This allows PPP
devices to be properly cleaned up by unregister_netdev() and friends.
So checking for ppp->owner is now an accurate test to decide if a PPP
device should be unregistered.

Setting ppp->owner is done in ppp_create_interface(), before device
registration, in order to avoid unprotected modification of this field.

Finally, ppp_exit_net() now starts by unregistering all remaining PPP
devices to ensure that none will get unregistered after the call to
idr_destroy().

Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

pppoe: check sockaddr length in pppoe_connect()

2018-10-21T07:45:40+00:00

commit a49e2f5d5fb141884452ddb428f551b123d436b5 upstream.

We must validate sockaddr_len, otherwise userspace can pass fewer data
than we expect and we end up accessing invalid data.

Fixes: 224cf5ad14c0 ("ppp: Move the PPP drivers")
Reported-by: syzbot+4f03bdf92fdf9ef5ddab@syzkaller.appspotmail.com
Signed-off-by: Guillaume Nault 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

pppoe: take ->needed_headroom of lower device into account on xmit

2018-03-03T15:52:28+00:00

commit 02612bb05e51df8489db5e94d0cf8d1c81f87b0c upstream.

In pppoe_sendmsg(), reserving dev->hard_header_len bytes of headroom
was probably fine before the introduction of ->needed_headroom in
commit f5184d267c1a ("net: Allow netdevices to specify needed head/tailroom").

But now, virtual devices typically advertise the size of their overhead
in dev->needed_headroom, so we must also take it into account in
skb_reserve().
Allocation size of skb is also updated to take dev->needed_tailroom
into account and replace the arbitrary 32 bytes with the real size of
a PPPoE header.

This issue was discovered by syzbot, who connected a pppoe socket to a
gre device which had dev->header_ops->create == ipgre_header and
dev->hard_header_len == 0. Therefore, PPPoE didn't reserve any
headroom, and dev_hard_header() crashed when ipgre_header() tried to
prepend its header to skb->data.

skbuff: skb_under_panic: text:000000001d390b3a len:31 put:24
head:00000000d8ed776f data:000000008150e823 tail:0x7 end:0xc0 dev:gre0
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:104!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
    (ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 3670 Comm: syzkaller801466 Not tainted
4.15.0-rc7-next-20180115+ #97
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:skb_panic+0x162/0x1f0 net/core/skbuff.c:100
RSP: 0018:ffff8801d9bd7840 EFLAGS: 00010282
RAX: 0000000000000083 RBX: ffff8801d4f083c0 RCX: 0000000000000000
RDX: 0000000000000083 RSI: 1ffff1003b37ae92 RDI: ffffed003b37aefc
RBP: ffff8801d9bd78a8 R08: 1ffff1003b37ae8a R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff86200de0
R13: ffffffff84a981ad R14: 0000000000000018 R15: ffff8801d2d34180
FS:  00000000019c4880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000208bc000 CR3: 00000001d9111001 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  skb_under_panic net/core/skbuff.c:114 [inline]
  skb_push+0xce/0xf0 net/core/skbuff.c:1714
  ipgre_header+0x6d/0x4e0 net/ipv4/ip_gre.c:879
  dev_hard_header include/linux/netdevice.h:2723 [inline]
  pppoe_sendmsg+0x58e/0x8b0 drivers/net/ppp/pppoe.c:890
  sock_sendmsg_nosec net/socket.c:630 [inline]
  sock_sendmsg+0xca/0x110 net/socket.c:640
  sock_write_iter+0x31a/0x5d0 net/socket.c:909
  call_write_iter include/linux/fs.h:1775 [inline]
  do_iter_readv_writev+0x525/0x7f0 fs/read_write.c:653
  do_iter_write+0x154/0x540 fs/read_write.c:932
  vfs_writev+0x18a/0x340 fs/read_write.c:977
  do_writev+0xfc/0x2a0 fs/read_write.c:1012
  SYSC_writev fs/read_write.c:1085 [inline]
  SyS_writev+0x27/0x30 fs/read_write.c:1082
  entry_SYSCALL_64_fastpath+0x29/0xa0

Admittedly PPPoE shouldn't be allowed to run on non Ethernet-like
interfaces, but reserving space for ->needed_headroom is a more
fundamental issue that needs to be addressed first.

Same problem exists for __pppoe_xmit(), which also needs to take
dev->needed_headroom into account in skb_cow_head().

Fixes: f5184d267c1a ("net: Allow netdevices to specify needed head/tailroom")
Reported-by: syzbot+ed0838d0fa4c4f2b528e20286e6dc63effc7c14d@syzkaller.appspotmail.com
Signed-off-by: Guillaume Nault 
Reviewed-by: Xin Long 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

ppp: defer netns reference release for ppp channel

2016-11-20T01:16:47+00:00

commit 205e1e255c479f3fd77446415706463b282f94e4 upstream.

Matt reported that we have a NULL pointer dereference
in ppp_pernet() from ppp_connect_channel(),
i.e. pch->chan_net is NULL.

This is due to that a parallel ppp_unregister_channel()
could happen while we are in ppp_connect_channel(), during
which pch->chan_net set to NULL. Since we need a reference
to net per channel, it makes sense to sync the refcnt
with the life time of the channel, therefore we should
release this reference when we destroy it.

Fixes: 1f461dcdd296 ("ppp: take reference on channels netns")
Reported-by: Matt Bennett 
Cc: Paul Mackerras 
Cc: linux-ppp@vger.kernel.org
Cc: Guillaume Nault 
Cc: Cyrill Gorcunov 
Signed-off-by: Cong Wang 
Reviewed-by: Cyrill Gorcunov 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings