linux.git/kernel/bpf, branch v4.19.59

bpf, devmap: Add missing RCU read lock on flush

2019-07-14T06:11:11+00:00

[ Upstream commit 86723c8640633bee4b4588d3c7784ee7a0032f65 ]

.ndo_xdp_xmit() assumes it is called under RCU. For example virtio_net
uses RCU to detect it has setup the resources for tx. The assumption
accidentally broke when introducing bulk queue in devmap.

Fixes: 5d053f9da431 ("bpf: devmap prepare xdp frames for bulking")
Reported-by: David Ahern 
Signed-off-by: Toshiaki Makita 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Sasha Levin

bpf, devmap: Add missing bulk queue free

2019-07-14T06:11:11+00:00

[ Upstream commit edabf4d9dd905acd60048ea1579943801e3a4876 ]

dev_map_free() forgot to free bulk queue when freeing its entries.

Fixes: 5d053f9da431 ("bpf: devmap prepare xdp frames for bulking")
Signed-off-by: Toshiaki Makita 
Acked-by: Jesper Dangaard Brouer 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Sasha Levin

bpf, devmap: Fix premature entry free on destroying map

2019-07-14T06:11:11+00:00

[ Upstream commit d4dd153d551634683fccf8881f606fa9f3dfa1ef ]

dev_map_free() waits for flush_needed bitmap to be empty in order to
ensure all flush operations have completed before freeing its entries.
However the corresponding clear_bit() was called before using the
entries, so the entries could be used after free.

All access to the entries needs to be done before clearing the bit.
It seems commit a5e2da6e9787 ("bpf: netdev is never null in
__dev_map_flush") accidentally changed the clear_bit() and memory access
order.

Note that the problem happens only in __dev_map_flush(), not in
dev_map_flush_old(). dev_map_flush_old() is called only after nulling
out the corresponding netdev_map entry, so dev_map_free() never frees
the entry thus no such race happens there.

Fixes: a5e2da6e9787 ("bpf: netdev is never null in __dev_map_flush")
Signed-off-by: Toshiaki Makita 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Sasha Levin

bpf: fix bpf_jit_limit knob for PAGE_SIZE >= 64K

2019-07-10T07:53:47+00:00

[ Upstream commit fdadd04931c2d7cd294dc5b2b342863f94be53a3 ]

Michael and Sandipan report:

  Commit ede95a63b5 introduced a bpf_jit_limit tuneable to limit BPF
  JIT allocations. At compile time it defaults to PAGE_SIZE * 40000,
  and is adjusted again at init time if MODULES_VADDR is defined.

  For ppc64 kernels, MODULES_VADDR isn't defined, so we're stuck with
  the compile-time default at boot-time, which is 0x9c400000 when
  using 64K page size. This overflows the signed 32-bit bpf_jit_limit
  value:

  root@ubuntu:/tmp# cat /proc/sys/net/core/bpf_jit_limit
  -1673527296

  and can cause various unexpected failures throughout the network
  stack. In one case `strace dhclient eth0` reported:

  setsockopt(5, SOL_SOCKET, SO_ATTACH_FILTER, {len=11, filter=0x105dd27f8},
             16) = -1 ENOTSUPP (Unknown error 524)

  and similar failures can be seen with tools like tcpdump. This doesn't
  always reproduce however, and I'm not sure why. The more consistent
  failure I've seen is an Ubuntu 18.04 KVM guest booted on a POWER9
  host would time out on systemd/netplan configuring a virtio-net NIC
  with no noticeable errors in the logs.

Given this and also given that in near future some architectures like
arm64 will have a custom area for BPF JIT image allocations we should
get rid of the BPF_JIT_LIMIT_DEFAULT fallback / default entirely. For
4.21, we have an overridable bpf_jit_alloc_exec(), bpf_jit_free_exec()
so therefore add another overridable bpf_jit_alloc_exec_limit() helper
function which returns the possible size of the memory area for deriving
the default heuristic in bpf_jit_charge_init().

Like bpf_jit_alloc_exec() and bpf_jit_free_exec(), the new
bpf_jit_alloc_exec_limit() assumes that module_alloc() is the default
JIT memory provider, and therefore in case archs implement their custom
module_alloc() we use MODULES_{END,_VADDR} for limits and otherwise for
vmalloc_exec() cases like on ppc64 we use VMALLOC_{END,_START}.

Additionally, for archs supporting large page sizes, we should change
the sysctl to be handled as long to not run into sysctl restrictions
in future.

Fixes: ede95a63b5e8 ("bpf: add bpf_jit_limit knob to restrict unpriv allocations")
Reported-by: Sandipan Das 
Reported-by: Michael Roth 
Signed-off-by: Daniel Borkmann 
Tested-by: Michael Roth 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

bpf: fix unconnected udp hooks

2019-07-03T11:14:48+00:00

commit 983695fa676568fc0fe5ddd995c7267aabc24632 upstream.

Intention of cgroup bind/connect/sendmsg BPF hooks is to act transparently
to applications as also stated in original motivation in 7828f20e3779 ("Merge
branch 'bpf-cgroup-bind-connect'"). When recently integrating the latter
two hooks into Cilium to enable host based load-balancing with Kubernetes,
I ran into the issue that pods couldn't start up as DNS got broken. Kubernetes
typically sets up DNS as a service and is thus subject to load-balancing.

Upon further debugging, it turns out that the cgroupv2 sendmsg BPF hooks API
is currently insufficient and thus not usable as-is for standard applications
shipped with most distros. To break down the issue we ran into with a simple
example:

  # cat /etc/resolv.conf
  nameserver 147.75.207.207
  nameserver 147.75.207.208

For the purpose of a simple test, we set up above IPs as service IPs and
transparently redirect traffic to a different DNS backend server for that
node:

  # cilium service list
  ID   Frontend            Backend
  1    147.75.207.207:53   1 => 8.8.8.8:53
  2    147.75.207.208:53   1 => 8.8.8.8:53

The attached BPF program is basically selecting one of the backends if the
service IP/port matches on the cgroup hook. DNS breaks here, because the
hooks are not transparent enough to applications which have built-in msg_name
address checks:

  # nslookup 1.1.1.1
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.208#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  [...]
  ;; connection timed out; no servers could be reached

  # dig 1.1.1.1
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.208#53
  ;; reply from unexpected source: 8.8.8.8#53, expected 147.75.207.207#53
  [...]

  ; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> 1.1.1.1
  ;; global options: +cmd
  ;; connection timed out; no servers could be reached

For comparison, if none of the service IPs is used, and we tell nslookup
to use 8.8.8.8 directly it works just fine, of course:

  # nslookup 1.1.1.1 8.8.8.8
  1.1.1.1.in-addr.arpa	name = one.one.one.one.

In order to fix this and thus act more transparent to the application,
this needs reverse translation on recvmsg() side. A minimal fix for this
API is to add similar recvmsg() hooks behind the BPF cgroups static key
such that the program can track state and replace the current sockaddr_in{,6}
with the original service IP. From BPF side, this basically tracks the
service tuple plus socket cookie in an LRU map where the reverse NAT can
then be retrieved via map value as one example. Side-note: the BPF cgroups
static key should be converted to a per-hook static key in future.

Same example after this fix:

  # cilium service list
  ID   Frontend            Backend
  1    147.75.207.207:53   1 => 8.8.8.8:53
  2    147.75.207.208:53   1 => 8.8.8.8:53

Lookups work fine now:

  # nslookup 1.1.1.1
  1.1.1.1.in-addr.arpa    name = one.one.one.one.

  Authoritative answers can be found from:

  # dig 1.1.1.1

  ; <<>> DiG 9.11.3-1ubuntu1.7-Ubuntu <<>> 1.1.1.1
  ;; global options: +cmd
  ;; Got answer:
  ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 51550
  ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

  ;; OPT PSEUDOSECTION:
  ; EDNS: version: 0, flags:; udp: 512
  ;; QUESTION SECTION:
  ;1.1.1.1.                       IN      A

  ;; AUTHORITY SECTION:
  .                       23426   IN      SOA     a.root-servers.net. nstld.verisign-grs.com. 2019052001 1800 900 604800 86400

  ;; Query time: 17 msec
  ;; SERVER: 147.75.207.207#53(147.75.207.207)
  ;; WHEN: Tue May 21 12:59:38 UTC 2019
  ;; MSG SIZE  rcvd: 111

And from an actual packet level it shows that we're using the back end
server when talking via 147.75.207.20{7,8} front end:

  # tcpdump -i any udp
  [...]
  12:59:52.698732 IP foo.42011 > google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38)
  12:59:52.698735 IP foo.42011 > google-public-dns-a.google.com.domain: 18803+ PTR? 1.1.1.1.in-addr.arpa. (38)
  12:59:52.701208 IP google-public-dns-a.google.com.domain > foo.42011: 18803 1/0/0 PTR one.one.one.one. (67)
  12:59:52.701208 IP google-public-dns-a.google.com.domain > foo.42011: 18803 1/0/0 PTR one.one.one.one. (67)
  [...]

In order to be flexible and to have same semantics as in sendmsg BPF
programs, we only allow return codes in [1,1] range. In the sendmsg case
the program is called if msg->msg_name is present which can be the case
in both, connected and unconnected UDP.

The former only relies on the sockaddr_in{,6} passed via connect(2) if
passed msg->msg_name was NULL. Therefore, on recvmsg side, we act in similar
way to call into the BPF program whenever a non-NULL msg->msg_name was
passed independent of sk->sk_state being TCP_ESTABLISHED or not. Note
that for TCP case, the msg->msg_name is ignored in the regular recvmsg
path and therefore not relevant.

For the case of ip{,v6}_recv_error() paths, picked up via MSG_ERRQUEUE,
the hook is not called. This is intentional as it aligns with the same
semantics as in case of TCP cgroup BPF hooks right now. This might be
better addressed in future through a different bpf_attach_type such
that this case can be distinguished from the regular recvmsg paths,
for example.

Fixes: 1cedee13d25a ("bpf: Hooks for sys_sendmsg")
Signed-off-by: Daniel Borkmann 
Acked-by: Andrey Ignatov 
Acked-by: Martin KaFai Lau 
Acked-by: Martynas Pumputis 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Greg Kroah-Hartman

bpf: lpm_trie: check left child of last leftmost node for NULL

2019-07-03T11:14:48+00:00

commit da2577fdd0932ea4eefe73903f1130ee366767d2 upstream.

If the leftmost parent node of the tree has does not have a child
on the left side, then trie_get_next_key (and bpftool map dump) will
not look at the child on the right.  This leads to the traversal
missing elements.

Lookup is not affected.

Update selftest to handle this case.

Reproducer:

 bpftool map create /sys/fs/bpf/lpm type lpm_trie key 6 \
     value 1 entries 256 name test_lpm flags 1
 bpftool map update pinned /sys/fs/bpf/lpm key  8 0 0 0  0   0 value 1
 bpftool map update pinned /sys/fs/bpf/lpm key 16 0 0 0  0 128 value 2
 bpftool map dump   pinned /sys/fs/bpf/lpm

Returns only 1 element. (2 expected)

Fixes: b471f2f1de8b ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE")
Signed-off-by: Jonathan Lemon 
Acked-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Greg Kroah-Hartman

bpf: fix undefined behavior in narrow load handling

2019-06-15T09:54:03+00:00

[ Upstream commit e2f7fc0ac6957cabff4cecf6c721979b571af208 ]

Commit 31fd85816dbe ("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: 31fd85816dbe ("bpf: permits narrower load from bpf program context fields")
Reviewed-by: Alban Crequy 
Reviewed-by: Iago López Galeiras 
Signed-off-by: Krzesimir Nowak 
Cc: Yonghong Song 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Sasha Levin

bpf: devmap: fix use-after-free Read in __dev_map_entry_free

2019-05-31T13:46:04+00:00

commit 2baae3545327632167c0180e9ca1d467416f1919 upstream.

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: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot+457d3e2ffbcf31aee5c0@syzkaller.appspotmail.com
Acked-by: Toke Høiland-Jørgensen 
Acked-by: Jesper Dangaard Brouer 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Greg Kroah-Hartman

bpf: add bpf_jit_limit knob to restrict unpriv allocations

2019-05-31T13:46:03+00:00

commit ede95a63b5e84ddeea6b0c473b36ab8bfd8c6ce3 upstream.

Rick reported that the BPF JIT could potentially fill the entire module
space with BPF programs from unprivileged users which would prevent later
attempts to load normal kernel modules or privileged BPF programs, for
example. If JIT was enabled but unsuccessful to generate the image, then
before commit 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config")
we would always fall back to the BPF interpreter. Nowadays in the case
where the CONFIG_BPF_JIT_ALWAYS_ON could be set, then the load will abort
with a failure since the BPF interpreter was compiled out.

Add a global limit and enforce it for unprivileged users such that in case
of BPF interpreter compiled out we fail once the limit has been reached
or we fall back to BPF interpreter earlier w/o using module mem if latter
was compiled in. In a next step, fair share among unprivileged users can
be resolved in particular for the case where we would fail hard once limit
is reached.

Fixes: 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config")
Fixes: 0a14842f5a3c ("net: filter: Just In Time compiler for x86-64")
Co-Developed-by: Rick Edgecombe 
Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Cc: Eric Dumazet 
Cc: Jann Horn 
Cc: Kees Cook 
Cc: LKML 
Signed-off-by: Alexei Starovoitov 
Cc: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

bpf, lru: avoid messing with eviction heuristics upon syscall lookup

2019-05-25T16:23:48+00:00

commit 50b045a8c0ccf44f76640ac3eea8d80ca53979a3 upstream.

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: 29ba732acbee ("bpf: Add BPF_MAP_TYPE_LRU_HASH")
Fixes: 8f8449384ec3 ("bpf: Add BPF_MAP_TYPE_LRU_PERCPU_HASH")
Signed-off-by: Daniel Borkmann 
Acked-by: Martin KaFai Lau 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Greg Kroah-Hartman