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  1. 16 10月, 2018 1 次提交
    • E
      ipv6: mcast: fix a use-after-free in inet6_mc_check · dc012f36
      由 Eric Dumazet 提交于 
      syzbot found a use-after-free in inet6_mc_check [1]

The problem here is that inet6_mc_check() uses rcu
and read_lock(&iml->sflock)

So the fact that ip6_mc_leave_src() is called under RTNL
and the socket lock does not help us, we need to acquire
iml->sflock in write mode.

In the future, we should convert all this stuff to RCU.

[1]
BUG: KASAN: use-after-free in ipv6_addr_equal include/net/ipv6.h:521 [inline]
BUG: KASAN: use-after-free in inet6_mc_check+0xae7/0xb40 net/ipv6/mcast.c:649
Read of size 8 at addr ffff8801ce7f2510 by task syz-executor0/22432

CPU: 1 PID: 22432 Comm: syz-executor0 Not tainted 4.19.0-rc7+ #280
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+0x1c4/0x2b4 lib/dump_stack.c:113
 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 ipv6_addr_equal include/net/ipv6.h:521 [inline]
 inet6_mc_check+0xae7/0xb40 net/ipv6/mcast.c:649
 __raw_v6_lookup+0x320/0x3f0 net/ipv6/raw.c:98
 ipv6_raw_deliver net/ipv6/raw.c:183 [inline]
 raw6_local_deliver+0x3d3/0xcb0 net/ipv6/raw.c:240
 ip6_input_finish+0x467/0x1aa0 net/ipv6/ip6_input.c:345
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ip6_input+0xe9/0x600 net/ipv6/ip6_input.c:426
 ip6_mc_input+0x48a/0xd20 net/ipv6/ip6_input.c:503
 dst_input include/net/dst.h:450 [inline]
 ip6_rcv_finish+0x17a/0x330 net/ipv6/ip6_input.c:76
 NF_HOOK include/linux/netfilter.h:289 [inline]
 ipv6_rcv+0x120/0x640 net/ipv6/ip6_input.c:271
 __netif_receive_skb_one_core+0x14d/0x200 net/core/dev.c:4913
 __netif_receive_skb+0x2c/0x1e0 net/core/dev.c:5023
 netif_receive_skb_internal+0x12c/0x620 net/core/dev.c:5126
 napi_frags_finish net/core/dev.c:5664 [inline]
 napi_gro_frags+0x75a/0xc90 net/core/dev.c:5737
 tun_get_user+0x3189/0x4250 drivers/net/tun.c:1923
 tun_chr_write_iter+0xb9/0x154 drivers/net/tun.c:1968
 call_write_iter include/linux/fs.h:1808 [inline]
 do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
 do_iter_write+0x185/0x5f0 fs/read_write.c:959
 vfs_writev+0x1f1/0x360 fs/read_write.c:1004
 do_writev+0x11a/0x310 fs/read_write.c:1039
 __do_sys_writev fs/read_write.c:1112 [inline]
 __se_sys_writev fs/read_write.c:1109 [inline]
 __x64_sys_writev+0x75/0xb0 fs/read_write.c:1109
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457421
Code: 75 14 b8 14 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 34 b5 fb ff c3 48 83 ec 08 e8 1a 2d 00 00 48 89 04 24 b8 14 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 63 2d 00 00 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007f2d30ecaba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000000003e RCX: 0000000000457421
RDX: 0000000000000001 RSI: 00007f2d30ecabf0 RDI: 00000000000000f0
RBP: 0000000020000500 R08: 00000000000000f0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007f2d30ecb6d4
R13: 00000000004c4890 R14: 00000000004d7b90 R15: 00000000ffffffff

Allocated by task 22437:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc+0x14e/0x760 mm/slab.c:3727
 kmalloc include/linux/slab.h:518 [inline]
 sock_kmalloc+0x15a/0x1f0 net/core/sock.c:1983
 ip6_mc_source+0x14dd/0x1960 net/ipv6/mcast.c:427
 do_ipv6_setsockopt.isra.9+0x3afb/0x45d0 net/ipv6/ipv6_sockglue.c:743
 ipv6_setsockopt+0xbd/0x170 net/ipv6/ipv6_sockglue.c:933
 rawv6_setsockopt+0x59/0x140 net/ipv6/raw.c:1069
 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3038
 __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
 __do_sys_setsockopt net/socket.c:1913 [inline]
 __se_sys_setsockopt net/socket.c:1910 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 22430:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xcf/0x230 mm/slab.c:3813
 __sock_kfree_s net/core/sock.c:2004 [inline]
 sock_kfree_s+0x29/0x60 net/core/sock.c:2010
 ip6_mc_leave_src+0x11a/0x1d0 net/ipv6/mcast.c:2448
 __ipv6_sock_mc_close+0x20b/0x4e0 net/ipv6/mcast.c:310
 ipv6_sock_mc_close+0x158/0x1d0 net/ipv6/mcast.c:328
 inet6_release+0x40/0x70 net/ipv6/af_inet6.c:452
 __sock_release+0xd7/0x250 net/socket.c:579
 sock_close+0x19/0x20 net/socket.c:1141
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801ce7f2500
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 16 bytes inside of
 192-byte region [ffff8801ce7f2500, ffff8801ce7f25c0)
The buggy address belongs to the page:
page:ffffea000739fc80 count:1 mapcount:0 mapping:ffff8801da800040 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0006f6e548 ffffea000737b948 ffff8801da800040
raw: 0000000000000000 ffff8801ce7f2000 0000000100000010 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ce7f2400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801ce7f2480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8801ce7f2500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff8801ce7f2580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801ce7f2600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      dc012f36
  3. 22 7月, 2018 2 次提交
  5. 17 7月, 2018 1 次提交
    • H
      ipv6/mcast: init as INCLUDE when join SSM INCLUDE group · c7ea20c9
      由 Hangbin Liu 提交于 
      This an IPv6 version patch of "ipv4/igmp: init group mode as INCLUDE when
join source group". From RFC3810, part 6.1:

   If no per-interface state existed for that
   multicast address before the change (i.e., the change consisted of
   creating a new per-interface record), or if no state exists after the
   change (i.e., the change consisted of deleting a per-interface
   record), then the "non-existent" state is considered to have an
   INCLUDE filter mode and an empty source list.

Which means a new multicast group should start with state IN(). Currently,
for MLDv2 SSM JOIN_SOURCE_GROUP mode, we first call ipv6_sock_mc_join(),
then ip6_mc_source(), which will trigger a TO_IN() message instead of
ALLOW().

The issue was exposed by commit a052517a ("net/multicast: should not
send source list records when have filter mode change"). Before this change,
we sent both ALLOW(A) and TO_IN(A). Now, we only send TO_IN(A).

Fix it by adding a new parameter to init group mode. Also add some wrapper
functions to avoid changing too much code.

v1 -> v2:
In the first version I only cleared the group change record. But this is not
enough. Because when a new group join, it will init as EXCLUDE and trigger
a filter mode change in ip/ip6_mc_add_src(), which will clear all source
addresses sf_crcount. This will prevent early joined address sending state
change records if multi source addressed joined at the same time.

In v2 patch, I fixed it by directly initializing the mode to INCLUDE for SSM
JOIN_SOURCE_GROUP. I also split the original patch into two separated patches
for IPv4 and IPv6.

There is also a difference between v4 and v6 version. For IPv6, when the
interface goes down and up, we will send correct state change record with
unspecified IPv6 address (::) with function ipv6_mc_up(). But after DAD is
completed, we resend the change record TO_IN() in mld_send_initial_cr().
Fix it by sending ALLOW() for INCLUDE mode in mld_send_initial_cr().

Fixes: a052517a ("net/multicast: should not send source list records when have filter mode change")
Reviewed-by: NStefano Brivio <sbrivio@redhat.com>
Signed-off-by: NHangbin Liu <liuhangbin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      c7ea20c9
  7. 23 6月, 2018 1 次提交
  9. 16 5月, 2018 1 次提交
  11. 28 3月, 2018 1 次提交
  13. 27 3月, 2018 1 次提交
  15. 05 3月, 2018 1 次提交
  17. 20 2月, 2018 1 次提交
    • K
      net: Convert icmpv6_sk_ops, ndisc_net_ops and igmp6_net_ops · 1a2e9332
      由 Kirill Tkhai 提交于 
      These pernet_operations create and destroy net::ipv6.icmp_sk
socket, used to send ICMP or error reply.

Nobody can dereference the socket to handle a packet before
net is initialized, as there is no routing; nobody can do
that in parallel with exit, as all of devices are moved
to init_net or destroyed and there are no packets it-flight.
So, it's possible to mark these pernet_operations as async.

The same for ndisc_net_ops and for igmp6_net_ops. The last
one also creates and destroys /proc entries.
Signed-off-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1a2e9332
  19. 07 2月, 2018 1 次提交
  21. 20 1月, 2018 1 次提交
  23. 17 1月, 2018 1 次提交
    • A
      net: delete /proc THIS_MODULE references · 96890d62
      由 Alexey Dobriyan 提交于 
      /proc has been ignoring struct file_operations::owner field for 10 years.
Specifically, it started with commit 786d7e16
("Fix rmmod/read/write races in /proc entries"). Notice the chunk where
inode->i_fop is initialized with proxy struct file_operations for
regular files:

	-               if (de->proc_fops)
	-                       inode->i_fop = de->proc_fops;
	+               if (de->proc_fops) {
	+                       if (S_ISREG(inode->i_mode))
	+                               inode->i_fop = &proc_reg_file_ops;
	+                       else
	+                               inode->i_fop = de->proc_fops;
	+               }

VFS stopped pinning module at this point.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      96890d62
  25. 14 12月, 2017 1 次提交
    • E
      ipv6: mcast: better catch silly mtu values · b9b312a7
      由 Eric Dumazet 提交于 
      syzkaller reported crashes in IPv6 stack [1]

Xin Long found that lo MTU was set to silly values.

IPv6 stack reacts to changes to small MTU, by disabling itself under
RTNL.

But there is a window where threads not using RTNL can see a wrong
device mtu. This can lead to surprises, in mld code where it is assumed
the mtu is suitable.

Fix this by reading device mtu once and checking IPv6 minimal MTU.

[1]
 skbuff: skb_over_panic: text:0000000010b86b8d len:196 put:20
 head:000000003b477e60 data:000000000e85441e tail:0xd4 end:0xc0 dev:lo
 ------------[ 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: 0 Comm: swapper/1 Not tainted 4.15.0-rc2-mm1+ #39
 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
 Google 01/01/2011
 RIP: 0010:skb_panic+0x15c/0x1f0 net/core/skbuff.c:100
 RSP: 0018:ffff8801db307508 EFLAGS: 00010286
 RAX: 0000000000000082 RBX: ffff8801c517e840 RCX: 0000000000000000
 RDX: 0000000000000082 RSI: 1ffff1003b660e61 RDI: ffffed003b660e95
 RBP: ffff8801db307570 R08: 1ffff1003b660e23 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85bd4020
 R13: ffffffff84754ed2 R14: 0000000000000014 R15: ffff8801c4e26540
 FS:  0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000463610 CR3: 00000001c6698000 CR4: 00000000001406e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  <IRQ>
  skb_over_panic net/core/skbuff.c:109 [inline]
  skb_put+0x181/0x1c0 net/core/skbuff.c:1694
  add_grhead.isra.24+0x42/0x3b0 net/ipv6/mcast.c:1695
  add_grec+0xa55/0x1060 net/ipv6/mcast.c:1817
  mld_send_cr net/ipv6/mcast.c:1903 [inline]
  mld_ifc_timer_expire+0x4d2/0x770 net/ipv6/mcast.c:2448
  call_timer_fn+0x23b/0x840 kernel/time/timer.c:1320
  expire_timers kernel/time/timer.c:1357 [inline]
  __run_timers+0x7e1/0xb60 kernel/time/timer.c:1660
  run_timer_softirq+0x4c/0xb0 kernel/time/timer.c:1686
  __do_softirq+0x29d/0xbb2 kernel/softirq.c:285
  invoke_softirq kernel/softirq.c:365 [inline]
  irq_exit+0x1d3/0x210 kernel/softirq.c:405
  exiting_irq arch/x86/include/asm/apic.h:540 [inline]
  smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052
  apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Tested-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b9b312a7
  27. 22 11月, 2017 1 次提交
    • K
      treewide: setup_timer() -> timer_setup() · e99e88a9
      由 Kees Cook 提交于 
      This converts all remaining cases of the old setup_timer() API into using
timer_setup(), where the callback argument is the structure already
holding the struct timer_list. These should have no behavioral changes,
since they just change which pointer is passed into the callback with
the same available pointers after conversion. It handles the following
examples, in addition to some other variations.

Casting from unsigned long:

    void my_callback(unsigned long data)
    {
        struct something *ptr = (struct something *)data;
    ...
    }
    ...
    setup_timer(&ptr->my_timer, my_callback, ptr);

and forced object casts:

    void my_callback(struct something *ptr)
    {
    ...
    }
    ...
    setup_timer(&ptr->my_timer, my_callback, (unsigned long)ptr);

become:

    void my_callback(struct timer_list *t)
    {
        struct something *ptr = from_timer(ptr, t, my_timer);
    ...
    }
    ...
    timer_setup(&ptr->my_timer, my_callback, 0);

Direct function assignments:

    void my_callback(unsigned long data)
    {
        struct something *ptr = (struct something *)data;
    ...
    }
    ...
    ptr->my_timer.function = my_callback;

have a temporary cast added, along with converting the args:

    void my_callback(struct timer_list *t)
    {
        struct something *ptr = from_timer(ptr, t, my_timer);
    ...
    }
    ...
    ptr->my_timer.function = (TIMER_FUNC_TYPE)my_callback;

And finally, callbacks without a data assignment:

    void my_callback(unsigned long data)
    {
    ...
    }
    ...
    setup_timer(&ptr->my_timer, my_callback, 0);

have their argument renamed to verify they're unused during conversion:

    void my_callback(struct timer_list *unused)
    {
    ...
    }
    ...
    timer_setup(&ptr->my_timer, my_callback, 0);

The conversion is done with the following Coccinelle script:

spatch --very-quiet --all-includes --include-headers \
	-I ./arch/x86/include -I ./arch/x86/include/generated \
	-I ./include -I ./arch/x86/include/uapi \
	-I ./arch/x86/include/generated/uapi -I ./include/uapi \
	-I ./include/generated/uapi --include ./include/linux/kconfig.h \
	--dir . \
	--cocci-file ~/src/data/timer_setup.cocci

@fix_address_of@
expression e;
@@

 setup_timer(
-&(e)
+&e
 , ...)

// Update any raw setup_timer() usages that have a NULL callback, but
// would otherwise match change_timer_function_usage, since the latter
// will update all function assignments done in the face of a NULL
// function initialization in setup_timer().
@change_timer_function_usage_NULL@
expression _E;
identifier _timer;
type _cast_data;
@@

(
-setup_timer(&_E->_timer, NULL, _E);
+timer_setup(&_E->_timer, NULL, 0);
|
-setup_timer(&_E->_timer, NULL, (_cast_data)_E);
+timer_setup(&_E->_timer, NULL, 0);
|
-setup_timer(&_E._timer, NULL, &_E);
+timer_setup(&_E._timer, NULL, 0);
|
-setup_timer(&_E._timer, NULL, (_cast_data)&_E);
+timer_setup(&_E._timer, NULL, 0);
)

@change_timer_function_usage@
expression _E;
identifier _timer;
struct timer_list _stl;
identifier _callback;
type _cast_func, _cast_data;
@@

(
-setup_timer(&_E->_timer, _callback, _E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, &_callback, _E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, _callback, (_cast_data)_E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, &_callback, (_cast_data)_E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, (_cast_func)_callback, _E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, (_cast_func)&_callback, _E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, (_cast_func)_callback, (_cast_data)_E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, (_cast_func)&_callback, (_cast_data)_E);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E._timer, _callback, (_cast_data)_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, _callback, (_cast_data)&_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, &_callback, (_cast_data)_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, &_callback, (_cast_data)&_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, (_cast_func)_callback, (_cast_data)_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, (_cast_func)_callback, (_cast_data)&_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, (_cast_func)&_callback, (_cast_data)_E);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, (_cast_func)&_callback, (_cast_data)&_E);
+timer_setup(&_E._timer, _callback, 0);
|
 _E->_timer@_stl.function = _callback;
|
 _E->_timer@_stl.function = &_callback;
|
 _E->_timer@_stl.function = (_cast_func)_callback;
|
 _E->_timer@_stl.function = (_cast_func)&_callback;
|
 _E._timer@_stl.function = _callback;
|
 _E._timer@_stl.function = &_callback;
|
 _E._timer@_stl.function = (_cast_func)_callback;
|
 _E._timer@_stl.function = (_cast_func)&_callback;
)

// callback(unsigned long arg)
@change_callback_handle_cast
 depends on change_timer_function_usage@
identifier change_timer_function_usage._callback;
identifier change_timer_function_usage._timer;
type _origtype;
identifier _origarg;
type _handletype;
identifier _handle;
@@

 void _callback(
-_origtype _origarg
+struct timer_list *t
 )
 {
(
	... when != _origarg
	_handletype *_handle =
-(_handletype *)_origarg;
+from_timer(_handle, t, _timer);
	... when != _origarg
|
	... when != _origarg
	_handletype *_handle =
-(void *)_origarg;
+from_timer(_handle, t, _timer);
	... when != _origarg
|
	... when != _origarg
	_handletype *_handle;
	... when != _handle
	_handle =
-(_handletype *)_origarg;
+from_timer(_handle, t, _timer);
	... when != _origarg
|
	... when != _origarg
	_handletype *_handle;
	... when != _handle
	_handle =
-(void *)_origarg;
+from_timer(_handle, t, _timer);
	... when != _origarg
)
 }

// callback(unsigned long arg) without existing variable
@change_callback_handle_cast_no_arg
 depends on change_timer_function_usage &&
                     !change_callback_handle_cast@
identifier change_timer_function_usage._callback;
identifier change_timer_function_usage._timer;
type _origtype;
identifier _origarg;
type _handletype;
@@

 void _callback(
-_origtype _origarg
+struct timer_list *t
 )
 {
+	_handletype *_origarg = from_timer(_origarg, t, _timer);
+
	... when != _origarg
-	(_handletype *)_origarg
+	_origarg
	... when != _origarg
 }

// Avoid already converted callbacks.
@match_callback_converted
 depends on change_timer_function_usage &&
            !change_callback_handle_cast &&
	    !change_callback_handle_cast_no_arg@
identifier change_timer_function_usage._callback;
identifier t;
@@

 void _callback(struct timer_list *t)
 { ... }

// callback(struct something *handle)
@change_callback_handle_arg
 depends on change_timer_function_usage &&
	    !match_callback_converted &&
            !change_callback_handle_cast &&
            !change_callback_handle_cast_no_arg@
identifier change_timer_function_usage._callback;
identifier change_timer_function_usage._timer;
type _handletype;
identifier _handle;
@@

 void _callback(
-_handletype *_handle
+struct timer_list *t
 )
 {
+	_handletype *_handle = from_timer(_handle, t, _timer);
	...
 }

// If change_callback_handle_arg ran on an empty function, remove
// the added handler.
@unchange_callback_handle_arg
 depends on change_timer_function_usage &&
	    change_callback_handle_arg@
identifier change_timer_function_usage._callback;
identifier change_timer_function_usage._timer;
type _handletype;
identifier _handle;
identifier t;
@@

 void _callback(struct timer_list *t)
 {
-	_handletype *_handle = from_timer(_handle, t, _timer);
 }

// We only want to refactor the setup_timer() data argument if we've found
// the matching callback. This undoes changes in change_timer_function_usage.
@unchange_timer_function_usage
 depends on change_timer_function_usage &&
            !change_callback_handle_cast &&
            !change_callback_handle_cast_no_arg &&
	    !change_callback_handle_arg@
expression change_timer_function_usage._E;
identifier change_timer_function_usage._timer;
identifier change_timer_function_usage._callback;
type change_timer_function_usage._cast_data;
@@

(
-timer_setup(&_E->_timer, _callback, 0);
+setup_timer(&_E->_timer, _callback, (_cast_data)_E);
|
-timer_setup(&_E._timer, _callback, 0);
+setup_timer(&_E._timer, _callback, (_cast_data)&_E);
)

// If we fixed a callback from a .function assignment, fix the
// assignment cast now.
@change_timer_function_assignment
 depends on change_timer_function_usage &&
            (change_callback_handle_cast ||
             change_callback_handle_cast_no_arg ||
             change_callback_handle_arg)@
expression change_timer_function_usage._E;
identifier change_timer_function_usage._timer;
identifier change_timer_function_usage._callback;
type _cast_func;
typedef TIMER_FUNC_TYPE;
@@

(
 _E->_timer.function =
-_callback
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E->_timer.function =
-&_callback
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E->_timer.function =
-(_cast_func)_callback;
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E->_timer.function =
-(_cast_func)&_callback
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E._timer.function =
-_callback
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E._timer.function =
-&_callback;
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E._timer.function =
-(_cast_func)_callback
+(TIMER_FUNC_TYPE)_callback
 ;
|
 _E._timer.function =
-(_cast_func)&_callback
+(TIMER_FUNC_TYPE)_callback
 ;
)

// Sometimes timer functions are called directly. Replace matched args.
@change_timer_function_calls
 depends on change_timer_function_usage &&
            (change_callback_handle_cast ||
             change_callback_handle_cast_no_arg ||
             change_callback_handle_arg)@
expression _E;
identifier change_timer_function_usage._timer;
identifier change_timer_function_usage._callback;
type _cast_data;
@@

 _callback(
(
-(_cast_data)_E
+&_E->_timer
|
-(_cast_data)&_E
+&_E._timer
|
-_E
+&_E->_timer
)
 )

// If a timer has been configured without a data argument, it can be
// converted without regard to the callback argument, since it is unused.
@match_timer_function_unused_data@
expression _E;
identifier _timer;
identifier _callback;
@@

(
-setup_timer(&_E->_timer, _callback, 0);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, _callback, 0L);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E->_timer, _callback, 0UL);
+timer_setup(&_E->_timer, _callback, 0);
|
-setup_timer(&_E._timer, _callback, 0);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, _callback, 0L);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_E._timer, _callback, 0UL);
+timer_setup(&_E._timer, _callback, 0);
|
-setup_timer(&_timer, _callback, 0);
+timer_setup(&_timer, _callback, 0);
|
-setup_timer(&_timer, _callback, 0L);
+timer_setup(&_timer, _callback, 0);
|
-setup_timer(&_timer, _callback, 0UL);
+timer_setup(&_timer, _callback, 0);
|
-setup_timer(_timer, _callback, 0);
+timer_setup(_timer, _callback, 0);
|
-setup_timer(_timer, _callback, 0L);
+timer_setup(_timer, _callback, 0);
|
-setup_timer(_timer, _callback, 0UL);
+timer_setup(_timer, _callback, 0);
)

@change_callback_unused_data
 depends on match_timer_function_unused_data@
identifier match_timer_function_unused_data._callback;
type _origtype;
identifier _origarg;
@@

 void _callback(
-_origtype _origarg
+struct timer_list *unused
 )
 {
	... when != _origarg
 }
Signed-off-by: NKees Cook <keescook@chromium.org>
      e99e88a9
  29. 04 7月, 2017 1 次提交
  31. 16 6月, 2017 3 次提交
    • J
      networking: make skb_put & friends return void pointers · 4df864c1
      由 Johannes Berg 提交于 
      It seems like a historic accident that these return unsigned char *,
and in many places that means casts are required, more often than not.

Make these functions (skb_put, __skb_put and pskb_put) return void *
and remove all the casts across the tree, adding a (u8 *) cast only
where the unsigned char pointer was used directly, all done with the
following spatch:

    @@
    expression SKB, LEN;
    typedef u8;
    identifier fn = { skb_put, __skb_put };
    @@
    - *(fn(SKB, LEN))
    + *(u8 *)fn(SKB, LEN)

    @@
    expression E, SKB, LEN;
    identifier fn = { skb_put, __skb_put };
    type T;
    @@
    - E = ((T *)(fn(SKB, LEN)))
    + E = fn(SKB, LEN)

which actually doesn't cover pskb_put since there are only three
users overall.

A handful of stragglers were converted manually, notably a macro in
drivers/isdn/i4l/isdn_bsdcomp.c and, oddly enough, one of the many
instances in net/bluetooth/hci_sock.c. In the former file, I also
had to fix one whitespace problem spatch introduced.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      4df864c1
    • J
      networking: introduce and use skb_put_data() · 59ae1d12
      由 Johannes Berg 提交于 
      A common pattern with skb_put() is to just want to memcpy()
some data into the new space, introduce skb_put_data() for
this.

An spatch similar to the one for skb_put_zero() converts many
of the places using it:

    @@
    identifier p, p2;
    expression len, skb, data;
    type t, t2;
    @@
    (
    -p = skb_put(skb, len);
    +p = skb_put_data(skb, data, len);
    |
    -p = (t)skb_put(skb, len);
    +p = skb_put_data(skb, data, len);
    )
    (
    p2 = (t2)p;
    -memcpy(p2, data, len);
    |
    -memcpy(p, data, len);
    )

    @@
    type t, t2;
    identifier p, p2;
    expression skb, data;
    @@
    t *p;
    ...
    (
    -p = skb_put(skb, sizeof(t));
    +p = skb_put_data(skb, data, sizeof(t));
    |
    -p = (t *)skb_put(skb, sizeof(t));
    +p = skb_put_data(skb, data, sizeof(t));
    )
    (
    p2 = (t2)p;
    -memcpy(p2, data, sizeof(*p));
    |
    -memcpy(p, data, sizeof(*p));
    )

    @@
    expression skb, len, data;
    @@
    -memcpy(skb_put(skb, len), data, len);
    +skb_put_data(skb, data, len);

(again, manually post-processed to retain some comments)
Reviewed-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      59ae1d12
    • J
      networking: convert many more places to skb_put_zero() · b080db58
      由 Johannes Berg 提交于 
      There were many places that my previous spatch didn't find,
as pointed out by yuan linyu in various patches.

The following spatch found many more and also removes the
now unnecessary casts:

    @@
    identifier p, p2;
    expression len;
    expression skb;
    type t, t2;
    @@
    (
    -p = skb_put(skb, len);
    +p = skb_put_zero(skb, len);
    |
    -p = (t)skb_put(skb, len);
    +p = skb_put_zero(skb, len);
    )
    ... when != p
    (
    p2 = (t2)p;
    -memset(p2, 0, len);
    |
    -memset(p, 0, len);
    )

    @@
    type t, t2;
    identifier p, p2;
    expression skb;
    @@
    t *p;
    ...
    (
    -p = skb_put(skb, sizeof(t));
    +p = skb_put_zero(skb, sizeof(t));
    |
    -p = (t *)skb_put(skb, sizeof(t));
    +p = skb_put_zero(skb, sizeof(t));
    )
    ... when != p
    (
    p2 = (t2)p;
    -memset(p2, 0, sizeof(*p));
    |
    -memset(p, 0, sizeof(*p));
    )

    @@
    expression skb, len;
    @@
    -memset(skb_put(skb, len), 0, len);
    +skb_put_zero(skb, len);

Apply it to the tree (with one manual fixup to keep the
comment in vxlan.c, which spatch removed.)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      b080db58
  33. 29 3月, 2017 1 次提交
  35. 10 2月, 2017 1 次提交
  37. 17 1月, 2017 1 次提交
    • H
      mld: do not remove mld souce list info when set link down · 1666d49e
      由 Hangbin Liu 提交于 
      This is an IPv6 version of commit 24803f38 ("igmp: do not remove igmp
souce list..."). In mld_del_delrec(), we will restore back all source filter
info instead of flush them.

Move mld_clear_delrec() from ipv6_mc_down() to ipv6_mc_destroy_dev() since
we should not remove source list info when set link down. Remove
igmp6_group_dropped() in ipv6_mc_destroy_dev() since we have called it in
ipv6_mc_down().

Also clear all source info after igmp6_group_dropped() instead of in it
because ipv6_mc_down() will call igmp6_group_dropped().
Signed-off-by: NHangbin Liu <liuhangbin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1666d49e
  39. 21 10月, 2016 1 次提交
  41. 09 8月, 2016 1 次提交
  43. 04 3月, 2016 1 次提交
    • B
      mld, igmp: Fix reserved tailroom calculation · 1837b2e2
      由 Benjamin Poirier 提交于 
      The current reserved_tailroom calculation fails to take hlen and tlen into
account.

skb:
[__hlen__|__data____________|__tlen___|__extra__]
^                                               ^
head                                            skb_end_offset

In this representation, hlen + data + tlen is the size passed to alloc_skb.
"extra" is the extra space made available in __alloc_skb because of
rounding up by kmalloc. We can reorder the representation like so:

[__hlen__|__data____________|__extra__|__tlen___]
^                                               ^
head                                            skb_end_offset

The maximum space available for ip headers and payload without
fragmentation is min(mtu, data + extra). Therefore,
reserved_tailroom
= data + extra + tlen - min(mtu, data + extra)
= skb_end_offset - hlen - min(mtu, skb_end_offset - hlen - tlen)
= skb_tailroom - min(mtu, skb_tailroom - tlen) ; after skb_reserve(hlen)

Compare the second line to the current expression:
reserved_tailroom = skb_end_offset - min(mtu, skb_end_offset)
and we can see that hlen and tlen are not taken into account.

The min() in the third line can be expanded into:
if mtu < skb_tailroom - tlen:
	reserved_tailroom = skb_tailroom - mtu
else:
	reserved_tailroom = tlen

Depending on hlen, tlen, mtu and the number of multicast address records,
the current code may output skbs that have less tailroom than
dev->needed_tailroom or it may output more skbs than needed because not all
space available is used.

Fixes: 4c672e4b ("ipv6: mld: fix add_grhead skb_over_panic for devs with large MTUs")
Signed-off-by: NBenjamin Poirier <bpoirier@suse.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1837b2e2
  45. 17 11月, 2015 1 次提交
  47. 08 10月, 2015 1 次提交
  49. 18 9月, 2015 3 次提交
    • E
      netfilter: Pass net into okfn · 0c4b51f0
      由 Eric W. Biederman 提交于 
      This is immediately motivated by the bridge code that chains functions that
call into netfilter.  Without passing net into the okfns the bridge code would
need to guess about the best expression for the network namespace to process
packets in.

As net is frequently one of the first things computed in continuation functions
after netfilter has done it's job passing in the desired network namespace is in
many cases a code simplification.

To support this change the function dst_output_okfn is introduced to
simplify passing dst_output as an okfn.  For the moment dst_output_okfn
just silently drops the struct net.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0c4b51f0
    • E
      netfilter: Pass struct net into the netfilter hooks · 29a26a56
      由 Eric W. Biederman 提交于 
      Pass a network namespace parameter into the netfilter hooks.  At the
call site of the netfilter hooks the path a packet is taking through
the network stack is well known which allows the network namespace to
be easily and reliabily.

This allows the replacement of magic code like
"dev_net(state->in?:state->out)" that appears at the start of most
netfilter hooks with "state->net".

In almost all cases the network namespace passed in is derived
from the first network device passed in, guaranteeing those
paths will not see any changes in practice.

The exceptions are:
xfrm/xfrm_output.c:xfrm_output_resume()         xs_net(skb_dst(skb)->xfrm)
ipvs/ip_vs_xmit.c:ip_vs_nat_send_or_cont()      ip_vs_conn_net(cp)
ipvs/ip_vs_xmit.c:ip_vs_send_or_cont()          ip_vs_conn_net(cp)
ipv4/raw.c:raw_send_hdrinc()                    sock_net(sk)
ipv6/ip6_output.c:ip6_xmit()			sock_net(sk)
ipv6/ndisc.c:ndisc_send_skb()                   dev_net(skb->dev) not dev_net(dst->dev)
ipv6/raw.c:raw6_send_hdrinc()                   sock_net(sk)
br_netfilter_hooks.c:br_nf_pre_routing_finish() dev_net(skb->dev) before skb->dev is set to nf_bridge->physindev

In all cases these exceptions seem to be a better expression for the
network namespace the packet is being processed in then the historic
"dev_net(in?in:out)".  I am documenting them in case something odd
pops up and someone starts trying to track down what happened.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      29a26a56
    • E
      net: Merge dst_output and dst_output_sk · 5a70649e
      由 Eric W. Biederman 提交于 
      Add a sock paramter to dst_output making dst_output_sk superfluous.
Add a skb->sk parameter to all of the callers of dst_output
Have the callers of dst_output_sk call dst_output.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5a70649e
  51. 08 4月, 2015 1 次提交
    • D
      netfilter: Pass socket pointer down through okfn(). · 7026b1dd
      由 David Miller 提交于 
      On the output paths in particular, we have to sometimes deal with two
socket contexts.  First, and usually skb->sk, is the local socket that
generated the frame.

And second, is potentially the socket used to control a tunneling
socket, such as one the encapsulates using UDP.

We do not want to disassociate skb->sk when encapsulating in order
to fix this, because that would break socket memory accounting.

The most extreme case where this can cause huge problems is an
AF_PACKET socket transmitting over a vxlan device.  We hit code
paths doing checks that assume they are dealing with an ipv4
socket, but are actually operating upon the AF_PACKET one.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      7026b1dd
  53. 01 4月, 2015 2 次提交
  55. 19 3月, 2015 1 次提交
  57. 28 2月, 2015 2 次提交
  59. 17 11月, 2014 1 次提交
    • D
      ipv6: mld: fix add_grhead skb_over_panic for devs with large MTUs · feb91a02
      由 Daniel Borkmann 提交于 
      It has been reported that generating an MLD listener report on
devices with large MTUs (e.g. 9000) and a high number of IPv6
addresses can trigger a skb_over_panic():

skbuff: skb_over_panic: text:ffffffff80612a5d len:3776 put:20
head:ffff88046d751000 data:ffff88046d751010 tail:0xed0 end:0xec0
dev:port1
 ------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:100!
invalid opcode: 0000 [#1] SMP
Modules linked in: ixgbe(O)
CPU: 3 PID: 0 Comm: swapper/3 Tainted: G O 3.14.23+ #4
[...]
Call Trace:
 <IRQ>
 [<ffffffff80578226>] ? skb_put+0x3a/0x3b
 [<ffffffff80612a5d>] ? add_grhead+0x45/0x8e
 [<ffffffff80612e3a>] ? add_grec+0x394/0x3d4
 [<ffffffff80613222>] ? mld_ifc_timer_expire+0x195/0x20d
 [<ffffffff8061308d>] ? mld_dad_timer_expire+0x45/0x45
 [<ffffffff80255b5d>] ? call_timer_fn.isra.29+0x12/0x68
 [<ffffffff80255d16>] ? run_timer_softirq+0x163/0x182
 [<ffffffff80250e6f>] ? __do_softirq+0xe0/0x21d
 [<ffffffff8025112b>] ? irq_exit+0x4e/0xd3
 [<ffffffff802214bb>] ? smp_apic_timer_interrupt+0x3b/0x46
 [<ffffffff8063f10a>] ? apic_timer_interrupt+0x6a/0x70

mld_newpack() skb allocations are usually requested with dev->mtu
in size, since commit 72e09ad1 ("ipv6: avoid high order allocations")
we have changed the limit in order to be less likely to fail.

However, in MLD/IGMP code, we have some rather ugly AVAILABLE(skb)
macros, which determine if we may end up doing an skb_put() for
adding another record. To avoid possible fragmentation, we check
the skb's tailroom as skb->dev->mtu - skb->len, which is a wrong
assumption as the actual max allocation size can be much smaller.

The IGMP case doesn't have this issue as commit 57e1ab6e
("igmp: refine skb allocations") stores the allocation size in
the cb[].

Set a reserved_tailroom to make it fit into the MTU and use
skb_availroom() helper instead. This also allows to get rid of
igmp_skb_size().
Reported-by: NWei Liu <lw1a2.jing@gmail.com>
Fixes: 72e09ad1 ("ipv6: avoid high order allocations")
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: David L Stevens <david.stevens@oracle.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      feb91a02
  61. 06 11月, 2014 2 次提交
    • D
      ipv6: mld: fix add_grhead skb_over_panic for devs with large MTUs · 4c672e4b
      由 Daniel Borkmann 提交于 
      It has been reported that generating an MLD listener report on
devices with large MTUs (e.g. 9000) and a high number of IPv6
addresses can trigger a skb_over_panic():

skbuff: skb_over_panic: text:ffffffff80612a5d len:3776 put:20
head:ffff88046d751000 data:ffff88046d751010 tail:0xed0 end:0xec0
dev:port1
 ------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:100!
invalid opcode: 0000 [#1] SMP
Modules linked in: ixgbe(O)
CPU: 3 PID: 0 Comm: swapper/3 Tainted: G O 3.14.23+ #4
[...]
Call Trace:
 <IRQ>
 [<ffffffff80578226>] ? skb_put+0x3a/0x3b
 [<ffffffff80612a5d>] ? add_grhead+0x45/0x8e
 [<ffffffff80612e3a>] ? add_grec+0x394/0x3d4
 [<ffffffff80613222>] ? mld_ifc_timer_expire+0x195/0x20d
 [<ffffffff8061308d>] ? mld_dad_timer_expire+0x45/0x45
 [<ffffffff80255b5d>] ? call_timer_fn.isra.29+0x12/0x68
 [<ffffffff80255d16>] ? run_timer_softirq+0x163/0x182
 [<ffffffff80250e6f>] ? __do_softirq+0xe0/0x21d
 [<ffffffff8025112b>] ? irq_exit+0x4e/0xd3
 [<ffffffff802214bb>] ? smp_apic_timer_interrupt+0x3b/0x46
 [<ffffffff8063f10a>] ? apic_timer_interrupt+0x6a/0x70

mld_newpack() skb allocations are usually requested with dev->mtu
in size, since commit 72e09ad1 ("ipv6: avoid high order allocations")
we have changed the limit in order to be less likely to fail.

However, in MLD/IGMP code, we have some rather ugly AVAILABLE(skb)
macros, which determine if we may end up doing an skb_put() for
adding another record. To avoid possible fragmentation, we check
the skb's tailroom as skb->dev->mtu - skb->len, which is a wrong
assumption as the actual max allocation size can be much smaller.

The IGMP case doesn't have this issue as commit 57e1ab6e
("igmp: refine skb allocations") stores the allocation size in
the cb[].

Set a reserved_tailroom to make it fit into the MTU and use
skb_availroom() helper instead. This also allows to get rid of
igmp_skb_size().
Reported-by: NWei Liu <lw1a2.jing@gmail.com>
Fixes: 72e09ad1 ("ipv6: avoid high order allocations")
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: David L Stevens <david.stevens@oracle.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      4c672e4b
    • J
      net: Convert SEQ_START_TOKEN/seq_printf to seq_puts · 1744bea1
      由 Joe Perches 提交于 
      Using a single fixed string is smaller code size than using
a format and many string arguments.

Reduces overall code size a little.

$ size net/ipv4/igmp.o* net/ipv6/mcast.o* net/ipv6/ip6_flowlabel.o*
   text	   data	    bss	    dec	    hex	filename
  34269	   7012	  14824	  56105	   db29	net/ipv4/igmp.o.new
  34315	   7012	  14824	  56151	   db57	net/ipv4/igmp.o.old
  30078	   7869	  13200	  51147	   c7cb	net/ipv6/mcast.o.new
  30105	   7869	  13200	  51174	   c7e6	net/ipv6/mcast.o.old
  11434	   3748	   8580	  23762	   5cd2	net/ipv6/ip6_flowlabel.o.new
  11491	   3748	   8580	  23819	   5d0b	net/ipv6/ip6_flowlabel.o.old
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      1744bea1
  63. 23 9月, 2014 1 次提交
    • D
      ipv6: mld: answer mldv2 queries with mldv1 reports in mldv1 fallback · 35f7aa53
      由 Daniel Borkmann 提交于 
      RFC2710 (MLDv1), section 3.7. says:

  The length of a received MLD message is computed by taking the
  IPv6 Payload Length value and subtracting the length of any IPv6
  extension headers present between the IPv6 header and the MLD
  message. If that length is greater than 24 octets, that indicates
  that there are other fields present *beyond* the fields described
  above, perhaps belonging to a *future backwards-compatible* version
  of MLD. An implementation of the version of MLD specified in this
  document *MUST NOT* send an MLD message longer than 24 octets and
  MUST ignore anything past the first 24 octets of a received MLD
  message.

RFC3810 (MLDv2), section 8.2.1. states for *listeners* regarding
presence of MLDv1 routers:

  In order to be compatible with MLDv1 routers, MLDv2 hosts MUST
  operate in version 1 compatibility mode. [...] When Host
  Compatibility Mode is MLDv2, a host acts using the MLDv2 protocol
  on that interface. When Host Compatibility Mode is MLDv1, a host
  acts in MLDv1 compatibility mode, using *only* the MLDv1 protocol,
  on that interface. [...]

While section 8.3.1. specifies *router* behaviour regarding presence
of MLDv1 routers:

  MLDv2 routers may be placed on a network where there is at least
  one MLDv1 router. The following requirements apply:

  If an MLDv1 router is present on the link, the Querier MUST use
  the *lowest* version of MLD present on the network. This must be
  administratively assured. Routers that desire to be compatible
  with MLDv1 MUST have a configuration option to act in MLDv1 mode;
  if an MLDv1 router is present on the link, the system administrator
  must explicitly configure all MLDv2 routers to act in MLDv1 mode.
  When in MLDv1 mode, the Querier MUST send periodic General Queries
  truncated at the Multicast Address field (i.e., 24 bytes long),
  and SHOULD also warn about receiving an MLDv2 Query (such warnings
  must be rate-limited). The Querier MUST also fill in the Maximum
  Response Delay in the Maximum Response Code field, i.e., the
  exponential algorithm described in section 5.1.3. is not used. [...]

That means that we should not get queries from different versions of
MLD. When there's a MLDv1 router present, MLDv2 enforces truncation
and MRC == MRD (both fields are overlapping within the 24 octet range).

Section 8.3.2. specifies behaviour in the presence of MLDv1 multicast
address *listeners*:

  MLDv2 routers may be placed on a network where there are hosts
  that have not yet been upgraded to MLDv2. In order to be compatible
  with MLDv1 hosts, MLDv2 routers MUST operate in version 1 compatibility
  mode. MLDv2 routers keep a compatibility mode per multicast address
  record. The compatibility mode of a multicast address is determined
  from the Multicast Address Compatibility Mode variable, which can be
  in one of the two following states: MLDv1 or MLDv2.

  The Multicast Address Compatibility Mode of a multicast address
  record is set to MLDv1 whenever an MLDv1 Multicast Listener Report is
  *received* for that multicast address. At the same time, the Older
  Version Host Present timer for the multicast address is set to Older
  Version Host Present Timeout seconds. The timer is re-set whenever a
  new MLDv1 Report is received for that multicast address. If the Older
  Version Host Present timer expires, the router switches back to
  Multicast Address Compatibility Mode of MLDv2 for that multicast
  address. [...]

That means, what can happen is the following scenario, that hosts can
act in MLDv1 compatibility mode when they previously have received an
MLDv1 query (or, simply operate in MLDv1 mode-only); and at the same
time, an MLDv2 router could start up and transmits MLDv2 startup query
messages while being unaware of the current operational mode.

Given RFC2710, section 3.7 we would need to answer to that with an MLDv1
listener report, so that the router according to RFC3810, section 8.3.2.
would receive that and internally switch to MLDv1 compatibility as well.

Right now, I believe since the initial implementation of MLDv2, Linux
hosts would just silently drop such MLDv2 queries instead of replying
with an MLDv1 listener report, which would prevent a MLDv2 router going
into fallback mode (until it receives other MLDv1 queries).

Since the mapping of MRC to MRD in exactly such cases can make use of
the exponential algorithm from 5.1.3, we cannot [strictly speaking] be
aware in MLDv1 of the encoding in MRC, it seems also not mentioned by
the RFC. Since encodings are the same up to 32767, assume in such a
situation this value as a hard upper limit we would clamp. We have asked
one of the RFC authors on that regard, and he mentioned that there seem
not to be any implementations that make use of that exponential algorithm
on startup messages. In any case, this patch fixes this MLD
interoperability issue.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      35f7aa53