Commit Graph

1089 Commits

Author SHA1 Message Date
Thomas Gleixner
d2912cb15b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:55 +02:00
Thomas Gleixner
f85d208658 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 451
Based on 1 normalized pattern(s):

  this file is subject to the terms and conditions of version 2 of the
  gnu general public license see the file copying in the main
  directory of the linux distribution for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 5 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081200.872755311@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:08 +02:00
Thomas Gleixner
ddc64d0ac9 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 363
Based on 1 normalized pattern(s):

  released under terms in gpl version 2 see copying

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 5 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531081035.689962394@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:37:09 +02:00
Thomas Gleixner
5b497af42f treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of version 2 of the gnu general public license as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 64 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:36:38 +02:00
Thomas Gleixner
25763b3c86 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of version 2 of the gnu general public license as
  published by the free software foundation

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 107 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528171438.615055994@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:29:53 -07:00
Thomas Gleixner
2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00
Linus Torvalds
2c1212de6f SPDX update for 5.2-rc2, round 1
Here are series of patches that add SPDX tags to different kernel files,
 based on two different things:
   - SPDX entries are added to a bunch of files that we missed a year ago
     that do not have any license information at all.
 
     These were either missed because the tool saw the MODULE_LICENSE()
     tag, or some EXPORT_SYMBOL tags, and got confused and thought the
     file had a real license, or the files have been added since the last
     big sweep, or they were Makefile/Kconfig files, which we didn't
     touch last time.
 
   - Add GPL-2.0-only or GPL-2.0-or-later tags to files where our scan
     tools can determine the license text in the file itself.  Where this
     happens, the license text is removed, in order to cut down on the
     700+ different ways we have in the kernel today, in a quest to get
     rid of all of these.
 
 These patches have been out for review on the linux-spdx@vger mailing
 list, and while they were created by automatic tools, they were
 hand-verified by a bunch of different people, all whom names are on the
 patches are reviewers.
 
 The reason for these "large" patches is if we were to continue to
 progress at the current rate of change in the kernel, adding license
 tags to individual files in different subsystems, we would be finished
 in about 10 years at the earliest.
 
 There will be more series of these types of patches coming over the next
 few weeks as the tools and reviewers crunch through the more "odd"
 variants of how to say "GPLv2" that developers have come up with over
 the years, combined with other fun oddities (GPL + a BSD disclaimer?)
 that are being unearthed, with the goal for the whole kernel to be
 cleaned up.
 
 These diffstats are not small, 3840 files are touched, over 10k lines
 removed in just 24 patches.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 -----BEGIN PGP SIGNATURE-----
 
 iG0EABECAC0WIQT0tgzFv3jCIUoxPcsxR9QN2y37KQUCXOP8uw8cZ3JlZ0Brcm9h
 aC5jb20ACgkQMUfUDdst+ynmGQCgy3evqzleuOITDpuWaxewFdHqiJYAnA7KRw4H
 1KwtfRnMtG6dk/XaS7H7
 =O9lH
 -----END PGP SIGNATURE-----

Merge tag 'spdx-5.2-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull SPDX update from Greg KH:
 "Here is a series of patches that add SPDX tags to different kernel
  files, based on two different things:

   - SPDX entries are added to a bunch of files that we missed a year
     ago that do not have any license information at all.

     These were either missed because the tool saw the MODULE_LICENSE()
     tag, or some EXPORT_SYMBOL tags, and got confused and thought the
     file had a real license, or the files have been added since the
     last big sweep, or they were Makefile/Kconfig files, which we
     didn't touch last time.

   - Add GPL-2.0-only or GPL-2.0-or-later tags to files where our scan
     tools can determine the license text in the file itself. Where this
     happens, the license text is removed, in order to cut down on the
     700+ different ways we have in the kernel today, in a quest to get
     rid of all of these.

  These patches have been out for review on the linux-spdx@vger mailing
  list, and while they were created by automatic tools, they were
  hand-verified by a bunch of different people, all whom names are on
  the patches are reviewers.

  The reason for these "large" patches is if we were to continue to
  progress at the current rate of change in the kernel, adding license
  tags to individual files in different subsystems, we would be finished
  in about 10 years at the earliest.

  There will be more series of these types of patches coming over the
  next few weeks as the tools and reviewers crunch through the more
  "odd" variants of how to say "GPLv2" that developers have come up with
  over the years, combined with other fun oddities (GPL + a BSD
  disclaimer?) that are being unearthed, with the goal for the whole
  kernel to be cleaned up.

  These diffstats are not small, 3840 files are touched, over 10k lines
  removed in just 24 patches"

* tag 'spdx-5.2-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (24 commits)
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 25
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 24
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 23
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 22
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 21
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 20
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 19
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 18
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 17
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 15
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 14
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 12
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 11
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 10
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 9
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 7
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 5
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 4
  treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 3
  ...
2019-05-21 12:33:38 -07:00
Thomas Gleixner
457c899653 treewide: Add SPDX license identifier for missed files
Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:45 +02:00
Chenbo Feng
e547ff3f80 bpf: relax inode permission check for retrieving bpf program
For iptable module to load a bpf program from a pinned location, it
only retrieve a loaded program and cannot change the program content so
requiring a write permission for it might not be necessary.
Also when adding or removing an unrelated iptable rule, it might need to
flush and reload the xt_bpf related rules as well and triggers the inode
permission check. It might be better to remove the write premission
check for the inode so we won't need to grant write access to all the
processes that flush and restore iptables rules.

Signed-off-by: Chenbo Feng <fengc@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-16 11:31:49 -07:00
Daniel Borkmann
50b045a8c0 bpf, lru: avoid messing with eviction heuristics upon syscall lookup
One of the biggest issues we face right now with picking LRU map over
regular hash table is that a map walk out of user space, for example,
to just dump the existing entries or to remove certain ones, will
completely mess up LRU eviction heuristics and wrong entries such
as just created ones will get evicted instead. The reason for this
is that we mark an entry as "in use" via bpf_lru_node_set_ref() from
system call lookup side as well. Thus upon walk, all entries are
being marked, so information of actual least recently used ones
are "lost".

In case of Cilium where it can be used (besides others) as a BPF
based connection tracker, this current behavior causes disruption
upon control plane changes that need to walk the map from user space
to evict certain entries. Discussion result from bpfconf [0] was that
we should simply just remove marking from system call side as no
good use case could be found where it's actually needed there.
Therefore this patch removes marking for regular LRU and per-CPU
flavor. If there ever should be a need in future, the behavior could
be selected via map creation flag, but due to mentioned reason we
avoid this here.

  [0] http://vger.kernel.org/bpfconf.html

Fixes: 29ba732acb ("bpf: Add BPF_MAP_TYPE_LRU_HASH")
Fixes: 8f8449384e ("bpf: Add BPF_MAP_TYPE_LRU_PERCPU_HASH")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-14 10:47:29 -07:00
Daniel Borkmann
c6110222c6 bpf: add map_lookup_elem_sys_only for lookups from syscall side
Add a callback map_lookup_elem_sys_only() that map implementations
could use over map_lookup_elem() from system call side in case the
map implementation needs to handle the latter differently than from
the BPF data path. If map_lookup_elem_sys_only() is set, this will
be preferred pick for map lookups out of user space. This hook is
used in a follow-up fix for LRU map, but once development window
opens, we can convert other map types from map_lookup_elem() (here,
the one called upon BPF_MAP_LOOKUP_ELEM cmd is meant) over to use
the callback to simplify and clean up the latter.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-14 10:47:29 -07:00
Eric Dumazet
2baae35453 bpf: devmap: fix use-after-free Read in __dev_map_entry_free
synchronize_rcu() is fine when the rcu callbacks only need
to free memory (kfree_rcu() or direct kfree() call rcu call backs)

__dev_map_entry_free() is a bit more complex, so we need to make
sure that call queued __dev_map_entry_free() callbacks have completed.

sysbot report:

BUG: KASAN: use-after-free in dev_map_flush_old kernel/bpf/devmap.c:365
[inline]
BUG: KASAN: use-after-free in __dev_map_entry_free+0x2a8/0x300
kernel/bpf/devmap.c:379
Read of size 8 at addr ffff8801b8da38c8 by task ksoftirqd/1/18

CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.17.0+ #39
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+0x1b9/0x294 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+0x242/0x2fe mm/kasan/report.c:412
  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
  dev_map_flush_old kernel/bpf/devmap.c:365 [inline]
  __dev_map_entry_free+0x2a8/0x300 kernel/bpf/devmap.c:379
  __rcu_reclaim kernel/rcu/rcu.h:178 [inline]
  rcu_do_batch kernel/rcu/tree.c:2558 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2818 [inline]
  __rcu_process_callbacks kernel/rcu/tree.c:2785 [inline]
  rcu_process_callbacks+0xe9d/0x1760 kernel/rcu/tree.c:2802
  __do_softirq+0x2e0/0xaf5 kernel/softirq.c:284
  run_ksoftirqd+0x86/0x100 kernel/softirq.c:645
  smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164
  kthread+0x345/0x410 kernel/kthread.c:240
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

Allocated by task 6675:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
  kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620
  kmalloc include/linux/slab.h:513 [inline]
  kzalloc include/linux/slab.h:706 [inline]
  dev_map_alloc+0x208/0x7f0 kernel/bpf/devmap.c:102
  find_and_alloc_map kernel/bpf/syscall.c:129 [inline]
  map_create+0x393/0x1010 kernel/bpf/syscall.c:453
  __do_sys_bpf kernel/bpf/syscall.c:2351 [inline]
  __se_sys_bpf kernel/bpf/syscall.c:2328 [inline]
  __x64_sys_bpf+0x303/0x510 kernel/bpf/syscall.c:2328
  do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 26:
  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
  set_track mm/kasan/kasan.c:460 [inline]
  __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
  __cache_free mm/slab.c:3498 [inline]
  kfree+0xd9/0x260 mm/slab.c:3813
  dev_map_free+0x4fa/0x670 kernel/bpf/devmap.c:191
  bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262
  process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153
  worker_thread+0x181/0x13a0 kernel/workqueue.c:2296
  kthread+0x345/0x410 kernel/kthread.c:240
  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412

The buggy address belongs to the object at ffff8801b8da37c0
  which belongs to the cache kmalloc-512 of size 512
The buggy address is located 264 bytes inside of
  512-byte region [ffff8801b8da37c0, ffff8801b8da39c0)
The buggy address belongs to the page:
page:ffffea0006e368c0 count:1 mapcount:0 mapping:ffff8801da800940
index:0xffff8801b8da3540
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea0007217b88 ffffea0006e30cc8 ffff8801da800940
raw: ffff8801b8da3540 ffff8801b8da3040 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8801b8da3780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
  ffff8801b8da3800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801b8da3880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                               ^
  ffff8801b8da3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8801b8da3980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc

Fixes: 546ac1ffb7 ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot+457d3e2ffbcf31aee5c0@syzkaller.appspotmail.com
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-05-14 01:25:49 +02:00
Krzesimir Nowak
e2f7fc0ac6 bpf: fix undefined behavior in narrow load handling
Commit 31fd85816d ("bpf: permits narrower load from bpf program
context fields") made the verifier add AND instructions to clear the
unwanted bits with a mask when doing a narrow load. The mask is
computed with

  (1 << size * 8) - 1

where "size" is the size of the narrow load. When doing a 4 byte load
of a an 8 byte field the verifier shifts the literal 1 by 32 places to
the left. This results in an overflow of a signed integer, which is an
undefined behavior. Typically, the computed mask was zero, so the
result of the narrow load ended up being zero too.

Cast the literal to long long to avoid overflows. Note that narrow
load of the 4 byte fields does not have the undefined behavior,
because the load size can only be either 1 or 2 bytes, so shifting 1
by 8 or 16 places will not overflow it. And reading 4 bytes would not
be a narrow load of a 4 bytes field.

Fixes: 31fd85816d ("bpf: permits narrower load from bpf program context fields")
Reviewed-by: Alban Crequy <alban@kinvolk.io>
Reviewed-by: Iago López Galeiras <iago@kinvolk.io>
Signed-off-by: Krzesimir Nowak <krzesimir@kinvolk.io>
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-05-13 02:05:50 +02:00
Daniel Borkmann
af959b18fd bpf: fix out of bounds backwards jmps due to dead code removal
systemtap folks reported the following splat recently:

  [ 7790.862212] WARNING: CPU: 3 PID: 26759 at arch/x86/kernel/kprobes/core.c:1022 kprobe_fault_handler+0xec/0xf0
  [...]
  [ 7790.864113] CPU: 3 PID: 26759 Comm: sshd Not tainted 5.1.0-0.rc7.git1.1.fc31.x86_64 #1
  [ 7790.864198] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS[...]
  [ 7790.864314] RIP: 0010:kprobe_fault_handler+0xec/0xf0
  [ 7790.864375] Code: 48 8b 50 [...]
  [ 7790.864714] RSP: 0018:ffffc06800bdbb48 EFLAGS: 00010082
  [ 7790.864812] RAX: ffff9e2b75a16320 RBX: 0000000000000000 RCX: 0000000000000000
  [ 7790.865306] RDX: ffffffffffffffff RSI: 000000000000000e RDI: ffffc06800bdbbf8
  [ 7790.865514] RBP: ffffc06800bdbbf8 R08: 0000000000000000 R09: 0000000000000000
  [ 7790.865960] R10: 0000000000000000 R11: 0000000000000000 R12: ffffc06800bdbbf8
  [ 7790.866037] R13: ffff9e2ab56a0418 R14: ffff9e2b6d0bb400 R15: ffff9e2b6d268000
  [ 7790.866114] FS:  00007fde49937d80(0000) GS:ffff9e2b75a00000(0000) knlGS:0000000000000000
  [ 7790.866193] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 7790.866318] CR2: 0000000000000000 CR3: 000000012f312000 CR4: 00000000000006e0
  [ 7790.866419] Call Trace:
  [ 7790.866677]  do_user_addr_fault+0x64/0x480
  [ 7790.867513]  do_page_fault+0x33/0x210
  [ 7790.868002]  async_page_fault+0x1e/0x30
  [ 7790.868071] RIP: 0010:          (null)
  [ 7790.868144] Code: Bad RIP value.
  [ 7790.868229] RSP: 0018:ffffc06800bdbca8 EFLAGS: 00010282
  [ 7790.868362] RAX: ffff9e2b598b60f8 RBX: ffffc06800bdbe48 RCX: 0000000000000004
  [ 7790.868629] RDX: 0000000000000004 RSI: ffffc06800bdbc6c RDI: ffff9e2b598b60f0
  [ 7790.868834] RBP: ffffc06800bdbcf8 R08: 0000000000000000 R09: 0000000000000004
  [ 7790.870432] R10: 00000000ff6f7a03 R11: 0000000000000000 R12: 0000000000000001
  [ 7790.871859] R13: ffffc06800bdbcb8 R14: 0000000000000000 R15: ffff9e2acd0a5310
  [ 7790.873455]  ? vfs_read+0x5/0x170
  [ 7790.874639]  ? vfs_read+0x1/0x170
  [ 7790.875834]  ? trace_call_bpf+0xf6/0x260
  [ 7790.877044]  ? vfs_read+0x1/0x170
  [ 7790.878208]  ? vfs_read+0x5/0x170
  [ 7790.879345]  ? kprobe_perf_func+0x233/0x260
  [ 7790.880503]  ? vfs_read+0x1/0x170
  [ 7790.881632]  ? vfs_read+0x5/0x170
  [ 7790.882751]  ? kprobe_ftrace_handler+0x92/0xf0
  [ 7790.883926]  ? __vfs_read+0x30/0x30
  [ 7790.885050]  ? ftrace_ops_assist_func+0x94/0x100
  [ 7790.886183]  ? vfs_read+0x1/0x170
  [ 7790.887283]  ? vfs_read+0x5/0x170
  [ 7790.888348]  ? ksys_read+0x5a/0xe0
  [ 7790.889389]  ? do_syscall_64+0x5c/0xa0
  [ 7790.890401]  ? entry_SYSCALL_64_after_hwframe+0x49/0xbe

After some debugging, turns out that the logic in 2cbd95a5c4
("bpf: change parameters of call/branch offset adjustment") has
a bug that is exposed after 52875a04f4 ("bpf: verifier: remove
dead code") in that we miss some of the jump offset adjustments
after code patching when we remove dead code, more concretely,
upon backward jump spanning over the area that is being removed.

BPF insns of a case that was hit pre 52875a04f4b2:

  [...]
  676: (85) call bpf_perf_event_output#-47616
  677: (05) goto pc-636
  678: (62) *(u32 *)(r10 -64) = 0
  679: (bf) r7 = r10
  680: (07) r7 += -64
  681: (05) goto pc-44
  682: (05) goto pc-1
  683: (05) goto pc-1

BPF insns afterwards:

  [...]
  618: (85) call bpf_perf_event_output#-47616
  619: (05) goto pc-638
  620: (62) *(u32 *)(r10 -64) = 0
  621: (bf) r7 = r10
  622: (07) r7 += -64
  623: (05) goto pc-44

To illustrate the bug, situation looks as follows:
     ____
  0 |    | <-- foo: [...]
  1 |____|
  2 |____| <-- pos / end_new  ^
  3 |    |                    |
  4 |    |                    |  len
  5 |____|                    |  (remove region)
  6 |    | <-- end_old        v
  7 |    |
  8 |    | <-- curr  (jmp foo)
  9 |____|

The condition curr >= end_new && curr + off + 1 < end_new in the
branch delta adjustments is never hit because curr + off + 1 <
end_new is compared as unsigned and therefore curr + off + 1 >
end_new in unsigned realm as curr + off + 1 becomes negative
since the insns are memmove()'d before the offset adjustments.

Correct BPF insns after this fix:

  [...]
  618: (85) call bpf_perf_event_output#-47216
  619: (05) goto pc-578
  620: (62) *(u32 *)(r10 -64) = 0
  621: (bf) r7 = r10
  622: (07) r7 += -64
  623: (05) goto pc-44

Note that unprivileged case is not affected from this.

Fixes: 52875a04f4 ("bpf: verifier: remove dead code")
Fixes: 2cbd95a5c4 ("bpf: change parameters of call/branch offset adjustment")
Reported-by: Frank Ch. Eigler <fche@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-05-10 18:49:27 -07:00
Linus Torvalds
80f232121b Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:
 "Highlights:

   1) Support AES128-CCM ciphers in kTLS, from Vakul Garg.

   2) Add fib_sync_mem to control the amount of dirty memory we allow to
      queue up between synchronize RCU calls, from David Ahern.

   3) Make flow classifier more lockless, from Vlad Buslov.

   4) Add PHY downshift support to aquantia driver, from Heiner
      Kallweit.

   5) Add SKB cache for TCP rx and tx, from Eric Dumazet. This reduces
      contention on SLAB spinlocks in heavy RPC workloads.

   6) Partial GSO offload support in XFRM, from Boris Pismenny.

   7) Add fast link down support to ethtool, from Heiner Kallweit.

   8) Use siphash for IP ID generator, from Eric Dumazet.

   9) Pull nexthops even further out from ipv4/ipv6 routes and FIB
      entries, from David Ahern.

  10) Move skb->xmit_more into a per-cpu variable, from Florian
      Westphal.

  11) Improve eBPF verifier speed and increase maximum program size,
      from Alexei Starovoitov.

  12) Eliminate per-bucket spinlocks in rhashtable, and instead use bit
      spinlocks. From Neil Brown.

  13) Allow tunneling with GUE encap in ipvs, from Jacky Hu.

  14) Improve link partner cap detection in generic PHY code, from
      Heiner Kallweit.

  15) Add layer 2 encap support to bpf_skb_adjust_room(), from Alan
      Maguire.

  16) Remove SKB list implementation assumptions in SCTP, your's truly.

  17) Various cleanups, optimizations, and simplifications in r8169
      driver. From Heiner Kallweit.

  18) Add memory accounting on TX and RX path of SCTP, from Xin Long.

  19) Switch PHY drivers over to use dynamic featue detection, from
      Heiner Kallweit.

  20) Support flow steering without masking in dpaa2-eth, from Ioana
      Ciocoi.

  21) Implement ndo_get_devlink_port in netdevsim driver, from Jiri
      Pirko.

  22) Increase the strict parsing of current and future netlink
      attributes, also export such policies to userspace. From Johannes
      Berg.

  23) Allow DSA tag drivers to be modular, from Andrew Lunn.

  24) Remove legacy DSA probing support, also from Andrew Lunn.

  25) Allow ll_temac driver to be used on non-x86 platforms, from Esben
      Haabendal.

  26) Add a generic tracepoint for TX queue timeouts to ease debugging,
      from Cong Wang.

  27) More indirect call optimizations, from Paolo Abeni"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1763 commits)
  cxgb4: Fix error path in cxgb4_init_module
  net: phy: improve pause mode reporting in phy_print_status
  dt-bindings: net: Fix a typo in the phy-mode list for ethernet bindings
  net: macb: Change interrupt and napi enable order in open
  net: ll_temac: Improve error message on error IRQ
  net/sched: remove block pointer from common offload structure
  net: ethernet: support of_get_mac_address new ERR_PTR error
  net: usb: smsc: fix warning reported by kbuild test robot
  staging: octeon-ethernet: Fix of_get_mac_address ERR_PTR check
  net: dsa: support of_get_mac_address new ERR_PTR error
  net: dsa: sja1105: Fix status initialization in sja1105_get_ethtool_stats
  vrf: sit mtu should not be updated when vrf netdev is the link
  net: dsa: Fix error cleanup path in dsa_init_module
  l2tp: Fix possible NULL pointer dereference
  taprio: add null check on sched_nest to avoid potential null pointer dereference
  net: mvpp2: cls: fix less than zero check on a u32 variable
  net_sched: sch_fq: handle non connected flows
  net_sched: sch_fq: do not assume EDT packets are ordered
  net: hns3: use devm_kcalloc when allocating desc_cb
  net: hns3: some cleanup for struct hns3_enet_ring
  ...
2019-05-07 22:03:58 -07:00
Linus Torvalds
168e153d5e Merge branch 'work.icache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs inode freeing updates from Al Viro:
 "Introduction of separate method for RCU-delayed part of
  ->destroy_inode() (if any).

  Pretty much as posted, except that destroy_inode() stashes
  ->free_inode into the victim (anon-unioned with ->i_fops) before
  scheduling i_callback() and the last two patches (sockfs conversion
  and folding struct socket_wq into struct socket) are excluded - that
  pair should go through netdev once davem reopens his tree"

* 'work.icache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (58 commits)
  orangefs: make use of ->free_inode()
  shmem: make use of ->free_inode()
  hugetlb: make use of ->free_inode()
  overlayfs: make use of ->free_inode()
  jfs: switch to ->free_inode()
  fuse: switch to ->free_inode()
  ext4: make use of ->free_inode()
  ecryptfs: make use of ->free_inode()
  ceph: use ->free_inode()
  btrfs: use ->free_inode()
  afs: switch to use of ->free_inode()
  dax: make use of ->free_inode()
  ntfs: switch to ->free_inode()
  securityfs: switch to ->free_inode()
  apparmor: switch to ->free_inode()
  rpcpipe: switch to ->free_inode()
  bpf: switch to ->free_inode()
  mqueue: switch to ->free_inode()
  ufs: switch to ->free_inode()
  coda: switch to ->free_inode()
  ...
2019-05-07 10:57:05 -07:00
Linus Torvalds
0bc40e549a Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Ingo Molnar:
 "The changes in here are:

   - text_poke() fixes and an extensive set of executability lockdowns,
     to (hopefully) eliminate the last residual circumstances under
     which we are using W|X mappings even temporarily on x86 kernels.
     This required a broad range of surgery in text patching facilities,
     module loading, trampoline handling and other bits.

   - tweak page fault messages to be more informative and more
     structured.

   - remove DISCONTIGMEM support on x86-32 and make SPARSEMEM the
     default.

   - reduce KASLR granularity on 5-level paging kernels from 512 GB to
     1 GB.

   - misc other changes and updates"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
  x86/mm: Initialize PGD cache during mm initialization
  x86/alternatives: Add comment about module removal races
  x86/kprobes: Use vmalloc special flag
  x86/ftrace: Use vmalloc special flag
  bpf: Use vmalloc special flag
  modules: Use vmalloc special flag
  mm/vmalloc: Add flag for freeing of special permsissions
  mm/hibernation: Make hibernation handle unmapped pages
  x86/mm/cpa: Add set_direct_map_*() functions
  x86/alternatives: Remove the return value of text_poke_*()
  x86/jump-label: Remove support for custom text poker
  x86/modules: Avoid breaking W^X while loading modules
  x86/kprobes: Set instruction page as executable
  x86/ftrace: Set trampoline pages as executable
  x86/kgdb: Avoid redundant comparison of patched code
  x86/alternatives: Use temporary mm for text poking
  x86/alternatives: Initialize temporary mm for patching
  fork: Provide a function for copying init_mm
  uprobes: Initialize uprobes earlier
  x86/mm: Save debug registers when loading a temporary mm
  ...
2019-05-06 16:13:31 -07:00
David S. Miller
ff24e4980a Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Three trivial overlapping conflicts.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-05-02 22:14:21 -04:00
Al Viro
524845ff9c bpf: switch to ->free_inode()
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-05-01 22:43:26 -04:00
Rick Edgecombe
d53d2f78ce bpf: Use vmalloc special flag
Use new flag VM_FLUSH_RESET_PERMS for handling freeing of special
permissioned memory in vmalloc and remove places where memory was set RW
before freeing which is no longer needed. Don't track if the memory is RO
anymore because it is now tracked in vmalloc.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-19-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-30 12:37:59 +02:00
Martin KaFai Lau
6ac99e8f23 bpf: Introduce bpf sk local storage
After allowing a bpf prog to
- directly read the skb->sk ptr
- get the fullsock bpf_sock by "bpf_sk_fullsock()"
- get the bpf_tcp_sock by "bpf_tcp_sock()"
- get the listener sock by "bpf_get_listener_sock()"
- avoid duplicating the fields of "(bpf_)sock" and "(bpf_)tcp_sock"
  into different bpf running context.

this patch is another effort to make bpf's network programming
more intuitive to do (together with memory and performance benefit).

When bpf prog needs to store data for a sk, the current practice is to
define a map with the usual 4-tuples (src/dst ip/port) as the key.
If multiple bpf progs require to store different sk data, multiple maps
have to be defined.  Hence, wasting memory to store the duplicated
keys (i.e. 4 tuples here) in each of the bpf map.
[ The smallest key could be the sk pointer itself which requires
  some enhancement in the verifier and it is a separate topic. ]

Also, the bpf prog needs to clean up the elem when sk is freed.
Otherwise, the bpf map will become full and un-usable quickly.
The sk-free tracking currently could be done during sk state
transition (e.g. BPF_SOCK_OPS_STATE_CB).

The size of the map needs to be predefined which then usually ended-up
with an over-provisioned map in production.  Even the map was re-sizable,
while the sk naturally come and go away already, this potential re-size
operation is arguably redundant if the data can be directly connected
to the sk itself instead of proxy-ing through a bpf map.

This patch introduces sk->sk_bpf_storage to provide local storage space
at sk for bpf prog to use.  The space will be allocated when the first bpf
prog has created data for this particular sk.

The design optimizes the bpf prog's lookup (and then optionally followed by
an inline update).  bpf_spin_lock should be used if the inline update needs
to be protected.

BPF_MAP_TYPE_SK_STORAGE:
-----------------------
To define a bpf "sk-local-storage", a BPF_MAP_TYPE_SK_STORAGE map (new in
this patch) needs to be created.  Multiple BPF_MAP_TYPE_SK_STORAGE maps can
be created to fit different bpf progs' needs.  The map enforces
BTF to allow printing the sk-local-storage during a system-wise
sk dump (e.g. "ss -ta") in the future.

The purpose of a BPF_MAP_TYPE_SK_STORAGE map is not for lookup/update/delete
a "sk-local-storage" data from a particular sk.
Think of the map as a meta-data (or "type") of a "sk-local-storage".  This
particular "type" of "sk-local-storage" data can then be stored in any sk.

The main purposes of this map are mostly:
1. Define the size of a "sk-local-storage" type.
2. Provide a similar syscall userspace API as the map (e.g. lookup/update,
   map-id, map-btf...etc.)
3. Keep track of all sk's storages of this "type" and clean them up
   when the map is freed.

sk->sk_bpf_storage:
------------------
The main lookup/update/delete is done on sk->sk_bpf_storage (which
is a "struct bpf_sk_storage").  When doing a lookup,
the "map" pointer is now used as the "key" to search on the
sk_storage->list.  The "map" pointer is actually serving
as the "type" of the "sk-local-storage" that is being
requested.

To allow very fast lookup, it should be as fast as looking up an
array at a stable-offset.  At the same time, it is not ideal to
set a hard limit on the number of sk-local-storage "type" that the
system can have.  Hence, this patch takes a cache approach.
The last search result from sk_storage->list is cached in
sk_storage->cache[] which is a stable sized array.  Each
"sk-local-storage" type has a stable offset to the cache[] array.
In the future, a map's flag could be introduced to do cache
opt-out/enforcement if it became necessary.

The cache size is 16 (i.e. 16 types of "sk-local-storage").
Programs can share map.  On the program side, having a few bpf_progs
running in the networking hotpath is already a lot.  The bpf_prog
should have already consolidated the existing sock-key-ed map usage
to minimize the map lookup penalty.  16 has enough runway to grow.

All sk-local-storage data will be removed from sk->sk_bpf_storage
during sk destruction.

bpf_sk_storage_get() and bpf_sk_storage_delete():
------------------------------------------------
Instead of using bpf_map_(lookup|update|delete)_elem(),
the bpf prog needs to use the new helper bpf_sk_storage_get() and
bpf_sk_storage_delete().  The verifier can then enforce the
ARG_PTR_TO_SOCKET argument.  The bpf_sk_storage_get() also allows to
"create" new elem if one does not exist in the sk.  It is done by
the new BPF_SK_STORAGE_GET_F_CREATE flag.  An optional value can also be
provided as the initial value during BPF_SK_STORAGE_GET_F_CREATE.
The BPF_MAP_TYPE_SK_STORAGE also supports bpf_spin_lock.  Together,
it has eliminated the potential use cases for an equivalent
bpf_map_update_elem() API (for bpf_prog) in this patch.

Misc notes:
----------
1. map_get_next_key is not supported.  From the userspace syscall
   perspective,  the map has the socket fd as the key while the map
   can be shared by pinned-file or map-id.

   Since btf is enforced, the existing "ss" could be enhanced to pretty
   print the local-storage.

   Supporting a kernel defined btf with 4 tuples as the return key could
   be explored later also.

2. The sk->sk_lock cannot be acquired.  Atomic operations is used instead.
   e.g. cmpxchg is done on the sk->sk_bpf_storage ptr.
   Please refer to the source code comments for the details in
   synchronization cases and considerations.

3. The mem is charged to the sk->sk_omem_alloc as the sk filter does.

Benchmark:
---------
Here is the benchmark data collected by turning on
the "kernel.bpf_stats_enabled" sysctl.
Two bpf progs are tested:

One bpf prog with the usual bpf hashmap (max_entries = 8192) with the
sk ptr as the key. (verifier is modified to support sk ptr as the key
That should have shortened the key lookup time.)

Another bpf prog is with the new BPF_MAP_TYPE_SK_STORAGE.

Both are storing a "u32 cnt", do a lookup on "egress_skb/cgroup" for
each egress skb and then bump the cnt.  netperf is used to drive
data with 4096 connected UDP sockets.

BPF_MAP_TYPE_HASH with a modifier verifier (152ns per bpf run)
27: cgroup_skb  name egress_sk_map  tag 74f56e832918070b run_time_ns 58280107540 run_cnt 381347633
    loaded_at 2019-04-15T13:46:39-0700  uid 0
    xlated 344B  jited 258B  memlock 4096B  map_ids 16
    btf_id 5

BPF_MAP_TYPE_SK_STORAGE in this patch (66ns per bpf run)
30: cgroup_skb  name egress_sk_stora  tag d4aa70984cc7bbf6 run_time_ns 25617093319 run_cnt 390989739
    loaded_at 2019-04-15T13:47:54-0700  uid 0
    xlated 168B  jited 156B  memlock 4096B  map_ids 17
    btf_id 6

Here is a high-level picture on how are the objects organized:

       sk
    ┌──────┐
    │      │
    │      │
    │      │
    │*sk_bpf_storage─────▶ bpf_sk_storage
    └──────┘                 ┌───────┐
                 ┌───────────┤ list  │
                 │           │       │
                 │           │       │
                 │           │       │
                 │           └───────┘
                 │
                 │     elem
                 │  ┌────────┐
                 ├─▶│ snode  │
                 │  ├────────┤
                 │  │  data  │          bpf_map
                 │  ├────────┤        ┌─────────┐
                 │  │map_node│◀─┬─────┤  list   │
                 │  └────────┘  │     │         │
                 │              │     │         │
                 │     elem     │     │         │
                 │  ┌────────┐  │     └─────────┘
                 └─▶│ snode  │  │
                    ├────────┤  │
   bpf_map          │  data  │  │
 ┌─────────┐        ├────────┤  │
 │  list   ├───────▶│map_node│  │
 │         │        └────────┘  │
 │         │                    │
 │         │           elem     │
 └─────────┘        ┌────────┐  │
                 ┌─▶│ snode  │  │
                 │  ├────────┤  │
                 │  │  data  │  │
                 │  ├────────┤  │
                 │  │map_node│◀─┘
                 │  └────────┘
                 │
                 │
                 │          ┌───────┐
     sk          └──────────│ list  │
  ┌──────┐                  │       │
  │      │                  │       │
  │      │                  │       │
  │      │                  └───────┘
  │*sk_bpf_storage───────▶bpf_sk_storage
  └──────┘

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-27 09:07:04 -07:00
Matt Mullins
9df1c28bb7 bpf: add writable context for raw tracepoints
This is an opt-in interface that allows a tracepoint to provide a safe
buffer that can be written from a BPF_PROG_TYPE_RAW_TRACEPOINT program.
The size of the buffer must be a compile-time constant, and is checked
before allowing a BPF program to attach to a tracepoint that uses this
feature.

The pointer to this buffer will be the first argument of tracepoints
that opt in; the pointer is valid and can be bpf_probe_read() by both
BPF_PROG_TYPE_RAW_TRACEPOINT and BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE
programs that attach to such a tracepoint, but the buffer to which it
points may only be written by the latter.

Signed-off-by: Matt Mullins <mmullins@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-26 19:04:19 -07:00
Paul Chaignon
c6a9efa1d8 bpf: mark registers in all frames after pkt/null checks
In case of a null check on a pointer inside a subprog, we should mark all
registers with this pointer as either safe or unknown, in both the current
and previous frames.  Currently, only spilled registers and registers in
the current frame are marked.  Packet bound checks in subprogs have the
same issue.  This patch fixes it to mark registers in previous frames as
well.

A good reproducer for null checks looks as follow:

1: ptr = bpf_map_lookup_elem(map, &key);
2: ret = subprog(ptr) {
3:   return ptr != NULL;
4: }
5: if (ret)
6:   value = *ptr;

With the above, the verifier will complain on line 6 because it sees ptr
as map_value_or_null despite the null check in subprog 1.

Note that this patch fixes another resulting bug when using
bpf_sk_release():

1: sk = bpf_sk_lookup_tcp(...);
2: subprog(sk) {
3:   if (sk)
4:     bpf_sk_release(sk);
5: }
6: if (!sk)
7:   return 0;
8: return 1;

In the above, mark_ptr_or_null_regs will warn on line 6 because it will
try to free the reference state, even though it was already freed on
line 3.

Fixes: f4d7e40a5b ("bpf: introduce function calls (verification)")
Signed-off-by: Paul Chaignon <paul.chaignon@orange.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-25 17:20:06 -07:00
Stanislav Fomichev
118c8e9ae6 bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type
target_fd is target namespace. If there is a flow dissector BPF program
attached to that namespace, its (single) id is returned.

v5:
* drop net ref right after rcu unlock (Daniel Borkmann)

v4:
* add missing put_net (Jann Horn)

v3:
* add missing inline to skb_flow_dissector_prog_query static def
  (kbuild test robot <lkp@intel.com>)

v2:
* don't sleep in rcu critical section (Jakub Kicinski)
* check input prog_cnt (exit early)

Cc: Jann Horn <jannh@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-25 23:49:06 +02:00
Alexei Starovoitov
45a73c17bf bpf: drop bpf_verifier_lock
Drop bpf_verifier_lock for root to avoid being DoS-ed by unprivileged.
The BPF verifier is now fully parallel.
All unpriv users are still serialized by bpf_verifier_lock to avoid
exhausting kernel memory by running N parallel verifications.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-23 01:50:43 +02:00
Alexei Starovoitov
7df737e991 bpf: remove global variables
Move three global variables protected by bpf_verifier_lock into
'struct bpf_verifier_env' to allow parallel verification.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-23 01:50:43 +02:00
Jesper Dangaard Brouer
86d231459d bpf: cpumap memory prefetchw optimizations for struct page
A lot of the performance gain comes from this patch.

While analysing performance overhead it was found that the largest CPU
stalls were caused when touching the struct page area. It is first read with
a READ_ONCE from build_skb_around via page_is_pfmemalloc(), and when freed
written by page_frag_free() call.

Measurements show that the prefetchw (W) variant operation is needed to
achieve the performance gain. We believe this optimization it two fold,
first the W-variant saves one step in the cache-coherency protocol, and
second it helps us to avoid the non-temporal prefetch HW optimizations and
bring this into all cache-levels. It might be worth investigating if
prefetch into L2 will have the same benefit.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-17 19:09:25 -07:00
Jesper Dangaard Brouer
8f0504a97e bpf: cpumap do bulk allocation of SKBs
As cpumap now batch consume xdp_frame's from the ptr_ring, it knows how many
SKBs it need to allocate. Thus, lets bulk allocate these SKBs via
kmem_cache_alloc_bulk() API, and use the previously introduced function
build_skb_around().

Notice that the flag __GFP_ZERO asks the slab/slub allocator to clear the
memory for us. This does clear a larger area than needed, but my micro
benchmarks on Intel CPUs show that this is slightly faster due to being a
cacheline aligned area is cleared for the SKBs. (For SLUB allocator, there
is a future optimization potential, because SKBs will with high probability
originate from same page. If we can find/identify continuous memory areas
then the Intel CPU memset rep stos will have a real performance gain.)

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-17 19:09:25 -07:00
Jesper Dangaard Brouer
77361825bb bpf: cpumap use ptr_ring_consume_batched
Move ptr_ring dequeue outside loop, that allocate SKBs and calls network
stack, as these operations that can take some time. The ptr_ring is a
communication channel between CPUs, where we want to reduce/limit any
cacheline bouncing.

Do a concentrated bulk dequeue via ptr_ring_consume_batched, to shorten the
period and times the remote cacheline in ptr_ring is read

Batch size 8 is both to (1) limit BH-disable period, and (2) consume one
cacheline on 64-bit archs. After reducing the BH-disable section further
then we can consider changing this, while still thinking about L1 cacheline
size being active.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-17 19:09:24 -07:00
Prashant Bhole
0d306c31b2 bpf: use BPF_CAST_CALL for casting bpf call
verifier.c uses BPF_CAST_CALL for casting bpf call except at one
place in jit_subprogs(). Let's use the macro for consistency.

Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-16 19:28:31 -07:00
Alban Crequy
02a8c817a3 bpf: add map helper functions push, pop, peek in more BPF programs
commit f1a2e44a3a ("bpf: add queue and stack maps") introduced new BPF
helper functions:
- BPF_FUNC_map_push_elem
- BPF_FUNC_map_pop_elem
- BPF_FUNC_map_peek_elem

but they were made available only for network BPF programs. This patch
makes them available for tracepoint, cgroup and lirc programs.

Signed-off-by: Alban Crequy <alban@kinvolk.io>
Cc: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-16 10:24:02 +02:00
Jiong Wang
c342dc109a bpf: refactor "check_reg_arg" to eliminate code redundancy
There are a few "regs[regno]" here are there across "check_reg_arg", this
patch factor it out into a simple "reg" pointer. The intention is to
simplify code indentation and make the later patches in this set look
cleaner.

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 17:06:33 -07:00
Jiong Wang
55e7f3b5ac bpf: factor out reg and stack slot propagation into "propagate_liveness_reg"
After code refactor in previous patches, the propagation logic inside the
for loop in "propagate_liveness" becomes clear that they are good enough to
be factored out into a common function "propagate_liveness_reg".

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 17:06:33 -07:00
Jiong Wang
3f8cafa413 bpf: refactor propagate_liveness to eliminate code redundance
Access to reg states were not factored out, the consequence is long code
for dereferencing them which made the indentation not good for reading.

This patch factor out these code so the core code in the loop could be
easier to follow.

Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 17:06:33 -07:00
Jiong Wang
1b04aee7e2 bpf: refactor propagate_liveness to eliminate duplicated for loop
Propagation for register and stack slot are finished in separate for loop,
while they are perfect to be put into a single loop.

This could also let them share some common variables in later patches.

Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 17:06:33 -07:00
Andrey Ignatov
51356ac89b bpf: Fix distinct pointer types warning for ARCH=i386
Fix a new warning reported by kbuild for make ARCH=i386:

   In file included from kernel/bpf/cgroup.c:11:0:
   kernel/bpf/cgroup.c: In function '__cgroup_bpf_run_filter_sysctl':
   include/linux/kernel.h:827:29: warning: comparison of distinct pointer types lacks a cast
      (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                                ^
   include/linux/kernel.h:841:4: note: in expansion of macro '__typecheck'
      (__typecheck(x, y) && __no_side_effects(x, y))
       ^~~~~~~~~~~
   include/linux/kernel.h:851:24: note: in expansion of macro '__safe_cmp'
     __builtin_choose_expr(__safe_cmp(x, y), \
                           ^~~~~~~~~~
   include/linux/kernel.h:860:19: note: in expansion of macro '__careful_cmp'
    #define min(x, y) __careful_cmp(x, y, <)
                      ^~~~~~~~~~~~~
>> kernel/bpf/cgroup.c:837:17: note: in expansion of macro 'min'
      ctx.new_len = min(PAGE_SIZE, *pcount);
                    ^~~

Fixes: 4e63acdff8 ("bpf: Introduce bpf_sysctl_{get,set}_new_value helpers")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 16:11:55 -07:00
Andrey Ignatov
d7a4cb9b67 bpf: Introduce bpf_strtol and bpf_strtoul helpers
Add bpf_strtol and bpf_strtoul to convert a string to long and unsigned
long correspondingly. It's similar to user space strtol(3) and
strtoul(3) with a few changes to the API:

* instead of NUL-terminated C string the helpers expect buffer and
  buffer length;

* resulting long or unsigned long is returned in a separate
  result-argument;

* return value is used to indicate success or failure, on success number
  of consumed bytes is returned that can be used to identify position to
  read next if the buffer is expected to contain multiple integers;

* instead of *base* argument, *flags* is used that provides base in 5
  LSB, other bits are reserved for future use;

* number of supported bases is limited.

Documentation for the new helpers is provided in bpf.h UAPI.

The helpers are made available to BPF_PROG_TYPE_CGROUP_SYSCTL programs to
be able to convert string input to e.g. "ulongvec" output.

E.g. "net/ipv4/tcp_mem" consists of three ulong integers. They can be
parsed by calling to bpf_strtoul three times.

Implementation notes:

Implementation includes "../../lib/kstrtox.h" to reuse integer parsing
functions. It's done exactly same way as fs/proc/base.c already does.

Unfortunately existing kstrtoX function can't be used directly since
they fail if any invalid character is present right after integer in the
string. Existing simple_strtoX functions can't be used either since
they're obsolete and don't handle overflow properly.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:59 -07:00
Andrey Ignatov
57c3bb725a bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types
Currently the way to pass result from BPF helper to BPF program is to
provide memory area defined by pointer and size: func(void *, size_t).

It works great for generic use-case, but for simple types, such as int,
it's overkill and consumes two arguments when it could use just one.

Introduce new argument types ARG_PTR_TO_INT and ARG_PTR_TO_LONG to be
able to pass result from helper to program via pointer to int and long
correspondingly: func(int *) or func(long *).

New argument types are similar to ARG_PTR_TO_MEM with the following
differences:
* they don't require corresponding ARG_CONST_SIZE argument, predefined
  access sizes are used instead (32bit for int, 64bit for long);
* it's possible to use more than one such an argument in a helper;
* provided pointers have to be aligned.

It's easy to introduce similar ARG_PTR_TO_CHAR and ARG_PTR_TO_SHORT
argument types. It's not done due to lack of use-case though.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:59 -07:00
Andrey Ignatov
e1550bfe0d bpf: Add file_pos field to bpf_sysctl ctx
Add file_pos field to bpf_sysctl context to read and write sysctl file
position at which sysctl is being accessed (read or written).

The field can be used to e.g. override whole sysctl value on write to
sysctl even when sys_write is called by user space with file_pos > 0. Or
BPF program may reject such accesses.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:58 -07:00
Andrey Ignatov
4e63acdff8 bpf: Introduce bpf_sysctl_{get,set}_new_value helpers
Add helpers to work with new value being written to sysctl by user
space.

bpf_sysctl_get_new_value() copies value being written to sysctl into
provided buffer.

bpf_sysctl_set_new_value() overrides new value being written by user
space with a one from provided buffer. Buffer should contain string
representation of the value, similar to what can be seen in /proc/sys/.

Both helpers can be used only on sysctl write.

File position matters and can be managed by an interface that will be
introduced separately. E.g. if user space calls sys_write to a file in
/proc/sys/ at file position = X, where X > 0, then the value set by
bpf_sysctl_set_new_value() will be written starting from X. If program
wants to override whole value with specified buffer, file position has
to be set to zero.

Documentation for the new helpers is provided in bpf.h UAPI.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:58 -07:00
Andrey Ignatov
1d11b3016c bpf: Introduce bpf_sysctl_get_current_value helper
Add bpf_sysctl_get_current_value() helper to copy current sysctl value
into provided by BPF_PROG_TYPE_CGROUP_SYSCTL program buffer.

It provides same string as user space can see by reading corresponding
file in /proc/sys/, including new line, etc.

Documentation for the new helper is provided in bpf.h UAPI.

Since current value is kept in ctl_table->data in a parsed form,
ctl_table->proc_handler() with write=0 is called to read that data and
convert it to a string. Such a string can later be parsed by a program
using helpers that will be introduced separately.

Unfortunately it's not trivial to provide API to access parsed data due to
variety of data representations (string, intvec, uintvec, ulongvec,
custom structures, even NULL, etc). Instead it's assumed that user know
how to handle specific sysctl they're interested in and appropriate
helpers can be used.

Since ctl_table->proc_handler() expects __user buffer, conversion to
__user happens for kernel allocated one where the value is stored.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:58 -07:00
Andrey Ignatov
808649fb78 bpf: Introduce bpf_sysctl_get_name helper
Add bpf_sysctl_get_name() helper to copy sysctl name (/proc/sys/ entry)
into provided by BPF_PROG_TYPE_CGROUP_SYSCTL program buffer.

By default full name (w/o /proc/sys/) is copied, e.g. "net/ipv4/tcp_mem".

If BPF_F_SYSCTL_BASE_NAME flag is set, only base name will be copied,
e.g. "tcp_mem".

Documentation for the new helper is provided in bpf.h UAPI.

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:58 -07:00
Andrey Ignatov
7b146cebe3 bpf: Sysctl hook
Containerized applications may run as root and it may create problems
for whole host. Specifically such applications may change a sysctl and
affect applications in other containers.

Furthermore in existing infrastructure it may not be possible to just
completely disable writing to sysctl, instead such a process should be
gradual with ability to log what sysctl are being changed by a
container, investigate, limit the set of writable sysctl to currently
used ones (so that new ones can not be changed) and eventually reduce
this set to zero.

The patch introduces new program type BPF_PROG_TYPE_CGROUP_SYSCTL and
attach type BPF_CGROUP_SYSCTL to solve these problems on cgroup basis.

New program type has access to following minimal context:
	struct bpf_sysctl {
		__u32	write;
	};

Where @write indicates whether sysctl is being read (= 0) or written (=
1).

Helpers to access sysctl name and value will be introduced separately.

BPF_CGROUP_SYSCTL attach point is added to sysctl code right before
passing control to ctl_table->proc_handler so that BPF program can
either allow or deny access to sysctl.

Suggested-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:58 -07:00
Andrey Ignatov
b1cd609d9b bpf: Add base proto function for cgroup-bpf programs
Currently kernel/bpf/cgroup.c contains only one program type and one
proto function cgroup_dev_func_proto(). It'd be useful to have base
proto function that can be reused for new cgroup-bpf program types
coming soon.

Introduce cgroup_base_func_proto().

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-12 13:54:58 -07:00
David S. Miller
bb23581b9b Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:

====================
pull-request: bpf-next 2019-04-12

The following pull-request contains BPF updates for your *net-next* tree.

The main changes are:

1) Improve BPF verifier scalability for large programs through two
   optimizations: i) remove verifier states that are not useful in pruning,
   ii) stop walking parentage chain once first LIVE_READ is seen. Combined
   gives approx 20x speedup. Increase limits for accepting large programs
   under root, and add various stress tests, from Alexei.

2) Implement global data support in BPF. This enables static global variables
   for .data, .rodata and .bss sections to be properly handled which allows
   for more natural program development. This also opens up the possibility
   to optimize program workflow by compiling ELFs only once and later only
   rewriting section data before reload, from Daniel and with test cases and
   libbpf refactoring from Joe.

3) Add config option to generate BTF type info for vmlinux as part of the
   kernel build process. DWARF debug info is converted via pahole to BTF.
   Latter relies on libbpf and makes use of BTF deduplication algorithm which
   results in 100x savings compared to DWARF data. Resulting .BTF section is
   typically about 2MB in size, from Andrii.

4) Add BPF verifier support for stack access with variable offset from
   helpers and add various test cases along with it, from Andrey.

5) Extend bpf_skb_adjust_room() growth BPF helper to mark inner MAC header
   so that L2 encapsulation can be used for tc tunnels, from Alan.

6) Add support for input __sk_buff context in BPF_PROG_TEST_RUN so that
   users can define a subset of allowed __sk_buff fields that get fed into
   the test program, from Stanislav.

7) Add bpf fs multi-dimensional array tests for BTF test suite and fix up
   various UBSAN warnings in bpftool, from Yonghong.

8) Generate a pkg-config file for libbpf, from Luca.

9) Dump program's BTF id in bpftool, from Prashant.

10) libbpf fix to use smaller BPF log buffer size for AF_XDP's XDP
    program, from Magnus.

11) kallsyms related fixes for the case when symbols are not present in
    BPF selftests and samples, from Daniel
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-11 17:00:05 -07:00
Stanislav Fomichev
b0b9395d86 bpf: support input __sk_buff context in BPF_PROG_TEST_RUN
Add new set of arguments to bpf_attr for BPF_PROG_TEST_RUN:
* ctx_in/ctx_size_in - input context
* ctx_out/ctx_size_out - output context

The intended use case is to pass some meta data to the test runs that
operate on skb (this has being brought up on recent LPC).

For programs that use bpf_prog_test_run_skb, support __sk_buff input and
output. Initially, from input __sk_buff, copy _only_ cb and priority into
skb, all other non-zero fields are prohibited (with EINVAL).
If the user has set ctx_out/ctx_size_out, copy the potentially modified
__sk_buff back to the userspace.

We require all fields of input __sk_buff except the ones we explicitly
support to be set to zero. The expectation is that in the future we might
add support for more fields and we want to fail explicitly if the user
runs the program on the kernel where we don't yet support them.

The API is intentionally vague (i.e. we don't explicitly add __sk_buff
to bpf_attr, but ctx_in) to potentially let other test_run types use
this interface in the future (this can be xdp_md for xdp types for
example).

v4:
  * don't copy more than allowed in bpf_ctx_init [Martin]

v3:
  * handle case where ctx_in is NULL, but ctx_out is not [Martin]
  * convert size==0 checks to ptr==NULL checks and add some extra ptr
    checks [Martin]

v2:
  * Addressed comments from Martin Lau

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-04-11 10:21:40 +02:00
Daniel Borkmann
2824ecb701 bpf: allow for key-less BTF in array map
Given we'll be reusing BPF array maps for global data/bss/rodata
sections, we need a way to associate BTF DataSec type as its map
value type. In usual cases we have this ugly BPF_ANNOTATE_KV_PAIR()
macro hack e.g. via 38d5d3b3d5 ("bpf: Introduce BPF_ANNOTATE_KV_PAIR")
to get initial map to type association going. While more use cases
for it are discouraged, this also won't work for global data since
the use of array map is a BPF loader detail and therefore unknown
at compilation time. For array maps with just a single entry we make
an exception in terms of BTF in that key type is declared optional
if value type is of DataSec type. The latter LLVM is guaranteed to
emit and it also aligns with how we regard global data maps as just
a plain buffer area reusing existing map facilities for allowing
things like introspection with existing tools.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-09 17:05:46 -07:00
Daniel Borkmann
1dc9285184 bpf: kernel side support for BTF Var and DataSec
This work adds kernel-side verification, logging and seq_show dumping
of BTF Var and DataSec kinds which are emitted with latest LLVM. The
following constraints apply:

BTF Var must have:

- Its kind_flag is 0
- Its vlen is 0
- Must point to a valid type
- Type must not resolve to a forward type
- Size of underlying type must be > 0
- Must have a valid name
- Can only be a source type, not sink or intermediate one
- Name may include dots (e.g. in case of static variables
  inside functions)
- Cannot be a member of a struct/union
- Linkage so far can either only be static or global/allocated

BTF DataSec must have:

- Its kind_flag is 0
- Its vlen cannot be 0
- Its size cannot be 0
- Must have a valid name
- Can only be a source type, not sink or intermediate one
- Name may include dots (e.g. to represent .bss, .data, .rodata etc)
- Cannot be a member of a struct/union
- Inner btf_var_secinfo array with {type,offset,size} triple
  must be sorted by offset in ascending order
- Type must always point to BTF Var
- BTF resolved size of Var must be <= size provided by triple
- DataSec size must be >= sum of triple sizes (thus holes
  are allowed)

btf_var_resolve(), btf_ptr_resolve() and btf_modifier_resolve()
are on a high level quite similar but each come with slight,
subtle differences. They could potentially be a bit refactored
in future which hasn't been done here to ease review.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-09 17:05:46 -07:00
Daniel Borkmann
3e0ddc4f3f bpf: allow . char as part of the object name
Trivial addition to allow '.' aside from '_' as "special" characters
in the object name. Used to allow for substrings in maps from loader
side such as ".bss", ".data", ".rodata", but could also be useful for
other purposes.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-09 17:05:46 -07:00
Daniel Borkmann
87df15de44 bpf: add syscall side map freeze support
This patch adds a new BPF_MAP_FREEZE command which allows to
"freeze" the map globally as read-only / immutable from syscall
side.

Map permission handling has been refactored into map_get_sys_perms()
and drops FMODE_CAN_WRITE in case of locked map. Main use case is
to allow for setting up .rodata sections from the BPF ELF which
are loaded into the kernel, meaning BPF loader first allocates
map, sets up map value by copying .rodata section into it and once
complete, it calls BPF_MAP_FREEZE on the map fd to prevent further
modifications.

Right now BPF_MAP_FREEZE only takes map fd as argument while remaining
bpf_attr members are required to be zero. I didn't add write-only
locking here as counterpart since I don't have a concrete use-case
for it on my side, and I think it makes probably more sense to wait
once there is actually one. In that case bpf_attr can be extended
as usual with a flag field and/or others where flag 0 means that
we lock the map read-only hence this doesn't prevent to add further
extensions to BPF_MAP_FREEZE upon need.

A map creation flag like BPF_F_WRONCE was not considered for couple
of reasons: i) in case of a generic implementation, a map can consist
of more than just one element, thus there could be multiple map
updates needed to set the map into a state where it can then be
made immutable, ii) WRONCE indicates exact one-time write before
it is then set immutable. A generic implementation would set a bit
atomically on map update entry (if unset), indicating that every
subsequent update from then onwards will need to bail out there.
However, map updates can fail, so upon failure that flag would need
to be unset again and the update attempt would need to be repeated
for it to be eventually made immutable. While this can be made
race-free, this approach feels less clean and in combination with
reason i), it's not generic enough. A dedicated BPF_MAP_FREEZE
command directly sets the flag and caller has the guarantee that
map is immutable from syscall side upon successful return for any
future syscall invocations that would alter the map state, which
is also more intuitive from an API point of view. A command name
such as BPF_MAP_LOCK has been avoided as it's too close with BPF
map spin locks (which already has BPF_F_LOCK flag). BPF_MAP_FREEZE
is so far only enabled for privileged users.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2019-04-09 17:05:46 -07:00