linux-stable.git/drivers/net/tun.c, branch linux-3.16.y

tun: fix use-after-free when register netdev failed

2019-11-22T15:57:28+00:00

commit 77f22f92dff8e7b45c7786a430626d38071d4670 upstream.

I got a UAF repport in tun driver when doing fuzzy test:

[  466.269490] ==================================================================
[  466.271792] BUG: KASAN: use-after-free in tun_chr_read_iter+0x2ca/0x2d0
[  466.271806] Read of size 8 at addr ffff888372139250 by task tun-test/2699
[  466.271810]
[  466.271824] CPU: 1 PID: 2699 Comm: tun-test Not tainted 5.3.0-rc1-00001-g5a9433db2614-dirty #427
[  466.271833] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[  466.271838] Call Trace:
[  466.271858]  dump_stack+0xca/0x13e
[  466.271871]  ? tun_chr_read_iter+0x2ca/0x2d0
[  466.271890]  print_address_description+0x79/0x440
[  466.271906]  ? vprintk_func+0x5e/0xf0
[  466.271920]  ? tun_chr_read_iter+0x2ca/0x2d0
[  466.271935]  __kasan_report+0x15c/0x1df
[  466.271958]  ? tun_chr_read_iter+0x2ca/0x2d0
[  466.271976]  kasan_report+0xe/0x20
[  466.271987]  tun_chr_read_iter+0x2ca/0x2d0
[  466.272013]  do_iter_readv_writev+0x4b7/0x740
[  466.272032]  ? default_llseek+0x2d0/0x2d0
[  466.272072]  do_iter_read+0x1c5/0x5e0
[  466.272110]  vfs_readv+0x108/0x180
[  466.299007]  ? compat_rw_copy_check_uvector+0x440/0x440
[  466.299020]  ? fsnotify+0x888/0xd50
[  466.299040]  ? __fsnotify_parent+0xd0/0x350
[  466.299064]  ? fsnotify_first_mark+0x1e0/0x1e0
[  466.304548]  ? vfs_write+0x264/0x510
[  466.304569]  ? ksys_write+0x101/0x210
[  466.304591]  ? do_preadv+0x116/0x1a0
[  466.304609]  do_preadv+0x116/0x1a0
[  466.309829]  do_syscall_64+0xc8/0x600
[  466.309849]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  466.309861] RIP: 0033:0x4560f9
[  466.309875] Code: 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
[  466.309889] RSP: 002b:00007ffffa5166e8 EFLAGS: 00000206 ORIG_RAX: 0000000000000127
[  466.322992] RAX: ffffffffffffffda RBX: 0000000000400460 RCX: 00000000004560f9
[  466.322999] RDX: 0000000000000003 RSI: 00000000200008c0 RDI: 0000000000000003
[  466.323007] RBP: 00007ffffa516700 R08: 0000000000000004 R09: 0000000000000000
[  466.323014] R10: 0000000000000000 R11: 0000000000000206 R12: 000000000040cb10
[  466.323021] R13: 0000000000000000 R14: 00000000006d7018 R15: 0000000000000000
[  466.323057]
[  466.323064] Allocated by task 2605:
[  466.335165]  save_stack+0x19/0x80
[  466.336240]  __kasan_kmalloc.constprop.8+0xa0/0xd0
[  466.337755]  kmem_cache_alloc+0xe8/0x320
[  466.339050]  getname_flags+0xca/0x560
[  466.340229]  user_path_at_empty+0x2c/0x50
[  466.341508]  vfs_statx+0xe6/0x190
[  466.342619]  __do_sys_newstat+0x81/0x100
[  466.343908]  do_syscall_64+0xc8/0x600
[  466.345303]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  466.347034]
[  466.347517] Freed by task 2605:
[  466.348471]  save_stack+0x19/0x80
[  466.349476]  __kasan_slab_free+0x12e/0x180
[  466.350726]  kmem_cache_free+0xc8/0x430
[  466.351874]  putname+0xe2/0x120
[  466.352921]  filename_lookup+0x257/0x3e0
[  466.354319]  vfs_statx+0xe6/0x190
[  466.355498]  __do_sys_newstat+0x81/0x100
[  466.356889]  do_syscall_64+0xc8/0x600
[  466.358037]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  466.359567]
[  466.360050] The buggy address belongs to the object at ffff888372139100
[  466.360050]  which belongs to the cache names_cache of size 4096
[  466.363735] The buggy address is located 336 bytes inside of
[  466.363735]  4096-byte region [ffff888372139100, ffff88837213a100)
[  466.367179] The buggy address belongs to the page:
[  466.368604] page:ffffea000dc84e00 refcount:1 mapcount:0 mapping:ffff8883df1b4f00 index:0x0 compound_mapcount: 0
[  466.371582] flags: 0x2fffff80010200(slab|head)
[  466.372910] raw: 002fffff80010200 dead000000000100 dead000000000122 ffff8883df1b4f00
[  466.375209] raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
[  466.377778] page dumped because: kasan: bad access detected
[  466.379730]
[  466.380288] Memory state around the buggy address:
[  466.381844]  ffff888372139100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  466.384009]  ffff888372139180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  466.386131] >ffff888372139200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  466.388257]                                                  ^
[  466.390234]  ffff888372139280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  466.392512]  ffff888372139300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[  466.394667] ==================================================================

tun_chr_read_iter() accessed the memory which freed by free_netdev()
called by tun_set_iff():

        CPUA                                           CPUB
  tun_set_iff()
    alloc_netdev_mqs()
    tun_attach()
                                                  tun_chr_read_iter()
                                                    tun_get()
                                                    tun_do_read()
                                                      tun_ring_recv()
    register_netdevice() <-- inject error
    goto err_detach
    tun_detach_all() <-- set RCV_SHUTDOWN
    free_netdev() <-- called from
                     err_free_dev path
      netdev_freemem() <-- free the memory
                        without check refcount
      (In this path, the refcount cannot prevent
       freeing the memory of dev, and the memory
       will be used by dev_put() called by
       tun_chr_read_iter() on CPUB.)
                                                     (Break from tun_ring_recv(),
                                                     because RCV_SHUTDOWN is set)
                                                   tun_put()
                                                     dev_put() <-- use the memory
                                                                   freed by netdev_freemem()

Put the publishing of tfile->tun after register_netdevice(),
so tun_get() won't get the tun pointer that freed by
err_detach path if register_netdevice() failed.

Fixes: eb0fb363f920 ("tuntap: attach queue 0 before registering netdevice")
Reported-by: Hulk Robot 
Suggested-by: Jason Wang 
Signed-off-by: Yang Yingliang 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

Revert "drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets"

2019-08-13T11:39:29+00:00

commit 72f6510745592c87f612f62ae4f16bb002934df4 upstream.

This reverts commit 5188cd44c55db3e92cd9e77a40b5baa7ed4340f7.

Now that GSO layer can track if fragment id has been selected
and can allocate one if necessary, we don't need to do this in
tap and macvtap.  This reverts most of the code and only keeps
the new ipv6 fragment id generation function that is still needed.

Fixes: 3d0ad09412ff (drivers/net: Disable UFO through virtio)
Signed-off-by: Vladislav Yasevich 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

tun: forbid iface creation with rtnl ops

2019-02-11T17:54:16+00:00

commit 35b827b6d06199841a83839e8bb69c0cd13a28be upstream.

It's not supported right now (the goal of the initial patch was to support
'ip link del' only).

Before the patch:
$ ip link add foo type tun
[  239.632660] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[snip]
[  239.636410] RIP: 0010:register_netdevice+0x8e/0x3a0

This panic occurs because dev->netdev_ops is not set by tun_setup(). But to
have something usable, it will require more than just setting
netdev_ops.

Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX")
CC: Eric W. Biederman 
Signed-off-by: Nicolas Dichtel 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: Don't use extack]
Signed-off-by: Ben Hutchings

tun: Consistently configure generic netdev params via rtnetlink

2019-02-11T17:53:33+00:00

commit df52eab23d703142c766ac00bdb8db19d71238d0 upstream.

Configuring generic network device parameters on tun will fail in
presence of IFLA_INFO_KIND attribute in IFLA_LINKINFO nested attribute
since tun_validate() always return failure.

This can be visualized with following ip-link(8) command sequences:

  # ip link set dev tun0 group 100
  # ip link set dev tun0 group 100 type tun
  RTNETLINK answers: Invalid argument

with contrast to dummy and veth drivers:

  # ip link set dev dummy0 group 100
  # ip link set dev dummy0 type dummy

  # ip link set dev veth0 group 100
  # ip link set dev veth0 group 100 type veth

Fix by returning zero in tun_validate() when @data is NULL that is
always in case since rtnl_link_ops->maxtype is zero in tun driver.

Fixes: f019a7a594d9 ("tun: Implement ip link del tunXXX")
Signed-off-by: Serhey Popovych 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

tun: allow positive return values on dev_get_valid_name() call

2018-06-16T21:21:28+00:00

commit 5c25f65fd1e42685f7ccd80e0621829c105785d9 upstream.

If the name argument of dev_get_valid_name() contains "%d", it will try
to assign it a unit number in __dev__alloc_name() and return either the
unit number (>= 0) or an error code (< 0).
Considering positive values as error values prevent tun device creations
relying this mechanism, therefor we should only consider negative values
as errors here.

Signed-off-by: Julien Gomes 
Acked-by: Cong Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

tun/tap: sanitize TUNSETSNDBUF input

2018-01-01T20:52:02+00:00

commit 93161922c658c714715686cd0cf69b090cb9bf1d upstream.

Syzkaller found several variants of the lockup below by setting negative
values with the TUNSETSNDBUF ioctl.  This patch adds a sanity check
to both the tun and tap versions of this ioctl.

  watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [repro:2389]
  Modules linked in:
  irq event stamp: 329692056
  hardirqs last  enabled at (329692055): [] _raw_spin_unlock_irqrestore+0x31/0x75
  hardirqs last disabled at (329692056): [] apic_timer_interrupt+0x98/0xb0
  softirqs last  enabled at (35659740): [] __do_softirq+0x328/0x48c
  softirqs last disabled at (35659731): [] irq_exit+0xbc/0xd0
  CPU: 0 PID: 2389 Comm: repro Not tainted 4.14.0-rc7 #23
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  task: ffff880009452140 task.stack: ffff880006a20000
  RIP: 0010:_raw_spin_lock_irqsave+0x11/0x80
  RSP: 0018:ffff880006a27c50 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff10
  RAX: ffff880009ac68d0 RBX: ffff880006a27ce0 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: ffff880006a27ce0 RDI: ffff880009ac6900
  RBP: ffff880006a27c60 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000001 R11: 000000000063ff00 R12: ffff880009ac6900
  R13: ffff880006a27cf8 R14: 0000000000000001 R15: ffff880006a27cf8
  FS:  00007f4be4838700(0000) GS:ffff88000cc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000020101000 CR3: 0000000009616000 CR4: 00000000000006f0
  Call Trace:
   prepare_to_wait+0x26/0xc0
   sock_alloc_send_pskb+0x14e/0x270
   ? remove_wait_queue+0x60/0x60
   tun_get_user+0x2cc/0x19d0
   ? __tun_get+0x60/0x1b0
   tun_chr_write_iter+0x57/0x86
   __vfs_write+0x156/0x1e0
   vfs_write+0xf7/0x230
   SyS_write+0x57/0xd0
   entry_SYSCALL_64_fastpath+0x1f/0xbe
  RIP: 0033:0x7f4be4356df9
  RSP: 002b:00007ffc18101c08 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
  RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f4be4356df9
  RDX: 0000000000000046 RSI: 0000000020101000 RDI: 0000000000000005
  RBP: 00007ffc18101c40 R08: 0000000000000001 R09: 0000000000000001
  R10: 0000000000000001 R11: 0000000000000293 R12: 0000559c75f64780
  R13: 00007ffc18101d30 R14: 0000000000000000 R15: 0000000000000000

Fixes: 33dccbb050bb ("tun: Limit amount of queued packets per device")
Fixes: 20d29d7a916a ("net: macvtap driver")
Signed-off-by: Craig Gallek 
Reviewed-by: Eric Dumazet 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings

tun: call dev_get_valid_name() before register_netdevice()

2018-01-01T20:51:54+00:00

commit 0ad646c81b2182f7fa67ec0c8c825e0ee165696d upstream.

register_netdevice() could fail early when we have an invalid
dev name, in which case ->ndo_uninit() is not called. For tun
device, this is a problem because a timer etc. are already
initialized and it expects ->ndo_uninit() to clean them up.

We could move these initializations into a ->ndo_init() so
that register_netdevice() knows better, however this is still
complicated due to the logic in tun_detach().

Therefore, I choose to just call dev_get_valid_name() before
register_netdevice(), which is quicker and much easier to audit.
And for this specific case, it is already enough.

Fixes: 96442e42429e ("tuntap: choose the txq based on rxq")
Reported-by: Dmitry Alexeev 
Cc: Jason Wang 
Cc: "Michael S. Tsirkin" 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

tun: read vnet_hdr_sz once

2017-03-16T02:27:25+00:00

[ Upstream commit e1edab87faf6ca30cd137e0795bc73aa9a9a22ec ]

When IFF_VNET_HDR is enabled, a virtio_net header must precede data.
Data length is verified to be greater than or equal to expected header
length tun->vnet_hdr_sz before copying.

Read this value once and cache locally, as it can be updated between
the test and use (TOCTOU).

Signed-off-by: Willem de Bruijn 
Reported-by: Dmitry Vyukov 
CC: Eric Dumazet 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16:
 - Use ACCESS_ONCE() instead of READ_ONCE()
 - Adjust context]
Signed-off-by: Ben Hutchings

tun: Fix TUN_PKT_STRIP setting

2017-03-16T02:27:24+00:00

commit 2eb783c43e7cf807a45899c10ed556b6dc116625 upstream.

We set the flag TUN_PKT_STRIP if the user buffer provided is too
small to contain the entire packet plus meta-data.  However, this
has been broken ever since we added GSO meta-data.  VLAN acceleration
also has the same problem.

This patch fixes this by taking both into account when setting the
TUN_PKT_STRIP flag.

The fact that this has been broken for six years without anyone
realising means that nobody actually uses this flag.

Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr")
Signed-off-by: Herbert Xu 
Signed-off-by: David S. Miller 
Signed-off-by: Ben Hutchings

tun: fix transmit timestamp support

2016-11-20T01:17:17+00:00

commit 7b996243fab46092fb3a29c773c54be8152366e4 upstream.

Instead of using sock_tx_timestamp, use skb_tx_timestamp to record
software transmit timestamp of a packet.

sock_tx_timestamp resets and overrides the tx_flags of the skb.
The function is intended to be called from within the protocol
layer when creating the skb, not from a device driver. This is
inconsistent with other drivers and will cause issues for TCP.

In TCP, we intend to sample the timestamps for the last byte
for each sendmsg/sendpage. For that reason, tcp_sendmsg calls
tcp_tx_timestamp only with the last skb that it generates.
For example, if a 128KB message is split into two 64KB packets
we want to sample the SND timestamp of the last packet. The current
code in the tun driver, however, will result in sampling the SND
timestamp for both packets.

Also, when the last packet is split into smaller packets for
retranmission (see tcp_fragment), the tun driver will record
timestamps for all of the retransmitted packets and not only the
last packet.

Fixes: eda297729171 (tun: Support software transmit time stamping.)
Signed-off-by: Soheil Hassas Yeganeh 
Signed-off-by: Francis Yan 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller 
[bwh: Backported to 3.16: call to sock_tx_timestamp() was different]
Signed-off-by: Ben Hutchings