linux-stable.git/net/core, branch v5.4.49

net: core: device_rename: Use rwsem instead of a seqcount

2020-06-24T15:50:52+00:00

[ Upstream commit 11d6011c2cf29f7c8181ebde6c8bc0c4d83adcd7 ]

Sequence counters write paths are critical sections that must never be
preempted, and blocking, even for CONFIG_PREEMPTION=n, is not allowed.

Commit 5dbe7c178d3f ("net: fix kernel deadlock with interface rename and
netdev name retrieval.") handled a deadlock, observed with
CONFIG_PREEMPTION=n, where the devnet_rename seqcount read side was
infinitely spinning: it got scheduled after the seqcount write side
blocked inside its own critical section.

To fix that deadlock, among other issues, the commit added a
cond_resched() inside the read side section. While this will get the
non-preemptible kernel eventually unstuck, the seqcount reader is fully
exhausting its slice just spinning -- until TIF_NEED_RESCHED is set.

The fix is also still broken: if the seqcount reader belongs to a
real-time scheduling policy, it can spin forever and the kernel will
livelock.

Disabling preemption over the seqcount write side critical section will
not work: inside it are a number of GFP_KERNEL allocations and mutex
locking through the drivers/base/ :: device_rename() call chain.

>From all the above, replace the seqcount with a rwsem.

Fixes: 5dbe7c178d3f (net: fix kernel deadlock with interface rename and netdev name retrieval.)
Fixes: 30e6c9fa93cf (net: devnet_rename_seq should be a seqcount)
Fixes: c91f6df2db49 (sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name)
Cc: 
Reported-by: kbuild test robot  [ v1 missing up_read() on error exit ]
Reported-by: Dan Carpenter  [ v1 missing up_read() on error exit ]
Signed-off-by: Ahmed S. Darwish 
Reviewed-by: Sebastian Andrzej Siewior 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

sched/rt, net: Use CONFIG_PREEMPTION.patch

2020-06-24T15:50:52+00:00

[ Upstream commit 2da2b32fd9346009e9acdb68c570ca8d3966aba7 ]

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.

Update the comment to use CONFIG_PREEMPTION.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Sebastian Andrzej Siewior 
Signed-off-by: Thomas Gleixner 
Acked-by: David S. Miller 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: netdev@vger.kernel.org
Link: https://lore.kernel.org/r/20191015191821.11479-22-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

bpf: Fix memlock accounting for sock_hash

2020-06-24T15:50:44+00:00

[ Upstream commit 60e5ca8a64bad8f3e2e20a1e57846e497361c700 ]

Add missed bpf_map_charge_init() in sock_hash_alloc() and
correspondingly bpf_map_charge_finish() on ENOMEM.

It was found accidentally while working on unrelated selftest that
checks "map->memory.pages > 0" is true for all map types.

Before:
	# bpftool m l
	...
	3692: sockhash  name m_sockhash  flags 0x0
		key 4B  value 4B  max_entries 8  memlock 0B

After:
	# bpftool m l
	...
	84: sockmap  name m_sockmap  flags 0x0
		key 4B  value 4B  max_entries 8  memlock 4096B

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Andrey Ignatov 
Signed-off-by: Alexei Starovoitov 
Link: https://lore.kernel.org/bpf/20200612000857.2881453-1-rdna@fb.com
Signed-off-by: Sasha Levin

net/filter: Permit reading NET in load_bytes_relative when MAC not set

2020-06-24T15:50:43+00:00

[ Upstream commit 0f5d82f187e1beda3fe7295dfc500af266a5bd80 ]

Added a check in the switch case on start_header that checks for
the existence of the header, and in the case that MAC is not set
and the caller requests for MAC, -EFAULT. If the caller requests
for NET then MAC's existence is completely ignored.

There is no function to check NET header's existence and as far
as cgroup_skb/egress is concerned it should always be set.

Removed for ptr >= the start of header, considering offset is
bounded unsigned and should always be true. len <= end - mac is
redundant to ptr + len <= end.

Fixes: 3eee1f75f2b9 ("bpf: fix bpf_skb_load_bytes_relative pkt length check")
Signed-off-by: YiFei Zhu 
Signed-off-by: Daniel Borkmann 
Reviewed-by: Stanislav Fomichev 
Link: https://lore.kernel.org/bpf/76bb820ddb6a95f59a772ecbd8c8a336f646b362.1591812755.git.zhuyifei@google.com
Signed-off-by: Sasha Levin

bpf, sockhash: Synchronize delete from bucket list on map free

2020-06-24T15:50:42+00:00

[ Upstream commit 75e68e5bf2c7fa9d3e874099139df03d5952a3e1 ]

We can end up modifying the sockhash bucket list from two CPUs when a
sockhash is being destroyed (sock_hash_free) on one CPU, while a socket
that is in the sockhash is unlinking itself from it on another CPU
it (sock_hash_delete_from_link).

This results in accessing a list element that is in an undefined state as
reported by KASAN:

| ==================================================================
| BUG: KASAN: wild-memory-access in sock_hash_free+0x13c/0x280
| Write of size 8 at addr dead000000000122 by task kworker/2:1/95
|
| CPU: 2 PID: 95 Comm: kworker/2:1 Not tainted 5.7.0-rc7-02961-ge22c35ab0038-dirty #691
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
| Workqueue: events bpf_map_free_deferred
| Call Trace:
|  dump_stack+0x97/0xe0
|  ? sock_hash_free+0x13c/0x280
|  __kasan_report.cold+0x5/0x40
|  ? mark_lock+0xbc1/0xc00
|  ? sock_hash_free+0x13c/0x280
|  kasan_report+0x38/0x50
|  ? sock_hash_free+0x152/0x280
|  sock_hash_free+0x13c/0x280
|  bpf_map_free_deferred+0xb2/0xd0
|  ? bpf_map_charge_finish+0x50/0x50
|  ? rcu_read_lock_sched_held+0x81/0xb0
|  ? rcu_read_lock_bh_held+0x90/0x90
|  process_one_work+0x59a/0xac0
|  ? lock_release+0x3b0/0x3b0
|  ? pwq_dec_nr_in_flight+0x110/0x110
|  ? rwlock_bug.part.0+0x60/0x60
|  worker_thread+0x7a/0x680
|  ? _raw_spin_unlock_irqrestore+0x4c/0x60
|  kthread+0x1cc/0x220
|  ? process_one_work+0xac0/0xac0
|  ? kthread_create_on_node+0xa0/0xa0
|  ret_from_fork+0x24/0x30
| ==================================================================

Fix it by reintroducing spin-lock protected critical section around the
code that removes the elements from the bucket on sockhash free.

To do that we also need to defer processing of removed elements, until out
of atomic context so that we can unlink the socket from the map when
holding the sock lock.

Fixes: 90db6d772f74 ("bpf, sockmap: Remove bucket->lock from sock_{hash|map}_free")
Reported-by: Eric Dumazet 
Signed-off-by: Jakub Sitnicki 
Signed-off-by: Alexei Starovoitov 
Acked-by: John Fastabend 
Link: https://lore.kernel.org/bpf/20200607205229.2389672-3-jakub@cloudflare.com
Signed-off-by: Sasha Levin

bpf, sockhash: Fix memory leak when unlinking sockets in sock_hash_free

2020-06-24T15:50:19+00:00

[ Upstream commit 33a7c831565c43a7ee2f38c7df4c4a40e1dfdfed ]

When sockhash gets destroyed while sockets are still linked to it, we will
walk the bucket lists and delete the links. However, we are not freeing the
list elements after processing them, leaking the memory.

The leak can be triggered by close()'ing a sockhash map when it still
contains sockets, and observed with kmemleak:

  unreferenced object 0xffff888116e86f00 (size 64):
    comm "race_sock_unlin", pid 223, jiffies 4294731063 (age 217.404s)
    hex dump (first 32 bytes):
      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
      81 de e8 41 00 00 00 00 c0 69 2f 15 81 88 ff ff  ...A.....i/.....
    backtrace:
      [<00000000dd089ebb>] sock_hash_update_common+0x4ca/0x760
      [<00000000b8219bd5>] sock_hash_update_elem+0x1d2/0x200
      [<000000005e2c23de>] __do_sys_bpf+0x2046/0x2990
      [<00000000d0084618>] do_syscall_64+0xad/0x9a0
      [<000000000d96f263>] entry_SYSCALL_64_after_hwframe+0x49/0xb3

Fix it by freeing the list element when we're done with it.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Jakub Sitnicki 
Signed-off-by: Alexei Starovoitov 
Acked-by: John Fastabend 
Link: https://lore.kernel.org/bpf/20200607205229.2389672-2-jakub@cloudflare.com
Signed-off-by: Sasha Levin

bpf: Fix running sk_skb program types with ktls

2020-06-22T07:31:12+00:00

[ Upstream commit e91de6afa81c10e9f855c5695eb9a53168d96b73 ]

KTLS uses a stream parser to collect TLS messages and send them to
the upper layer tls receive handler. This ensures the tls receiver
has a full TLS header to parse when it is run. However, when a
socket has BPF_SK_SKB_STREAM_VERDICT program attached before KTLS
is enabled we end up with two stream parsers running on the same
socket.

The result is both try to run on the same socket. First the KTLS
stream parser runs and calls read_sock() which will tcp_read_sock
which in turn calls tcp_rcv_skb(). This dequeues the skb from the
sk_receive_queue. When this is done KTLS code then data_ready()
callback which because we stacked KTLS on top of the bpf stream
verdict program has been replaced with sk_psock_start_strp(). This
will in turn kick the stream parser again and eventually do the
same thing KTLS did above calling into tcp_rcv_skb() and dequeuing
a skb from the sk_receive_queue.

At this point the data stream is broke. Part of the stream was
handled by the KTLS side some other bytes may have been handled
by the BPF side. Generally this results in either missing data
or more likely a "Bad Message" complaint from the kTLS receive
handler as the BPF program steals some bytes meant to be in a
TLS header and/or the TLS header length is no longer correct.

We've already broke the idealized model where we can stack ULPs
in any order with generic callbacks on the TX side to handle this.
So in this patch we do the same thing but for RX side. We add
a sk_psock_strp_enabled() helper so TLS can learn a BPF verdict
program is running and add a tls_sw_has_ctx_rx() helper so BPF
side can learn there is a TLS ULP on the socket.

Then on BPF side we omit calling our stream parser to avoid
breaking the data stream for the KTLS receiver. Then on the
KTLS side we call BPF_SK_SKB_STREAM_VERDICT once the KTLS
receiver is done with the packet but before it posts the
msg to userspace. This gives us symmetry between the TX and
RX halfs and IMO makes it usable again. On the TX side we
process packets in this order BPF -> TLS -> TCP and on
the receive side in the reverse order TCP -> TLS -> BPF.

Discovered while testing OpenSSL 3.0 Alpha2.0 release.

Fixes: d829e9c4112b5 ("tls: convert to generic sk_msg interface")
Signed-off-by: John Fastabend
Signed-off-by: Alexei Starovoitov
Link: https://lore.kernel.org/bpf/159079361946.5745.605854335665044485.stgit@john-Precision-5820-Tower
Signed-off-by: Alexei Starovoitov
Signed-off-by: Sasha Levin

bpf: Refactor sockmap redirect code so its easy to reuse

2020-06-22T07:31:11+00:00

[ Upstream commit ca2f5f21dbbd5e3a00cd3e97f728aa2ca0b2e011 ]

We will need this block of code called from tls context shortly
lets refactor the redirect logic so its easy to use. This also
cleans up the switch stmt so we have fewer fallthrough cases.

No logic changes are intended.

Fixes: d829e9c4112b5 ("tls: convert to generic sk_msg interface")
Signed-off-by: John Fastabend 
Signed-off-by: Alexei Starovoitov 
Reviewed-by: Jakub Sitnicki 
Acked-by: Song Liu 
Link: https://lore.kernel.org/bpf/159079360110.5745.7024009076049029819.stgit@john-Precision-5820-Tower
Signed-off-by: Alexei Starovoitov 
Signed-off-by: Sasha Levin

__netif_receive_skb_core: pass skb by reference

2020-06-03T06:20:47+00:00

[ Upstream commit c0bbbdc32febd4f034ecbf3ea17865785b2c0652 ]

__netif_receive_skb_core may change the skb pointer passed into it (e.g.
in rx_handler). The original skb may be freed as a result of this
operation.

The callers of __netif_receive_skb_core may further process original skb
by using pt_prev pointer returned by __netif_receive_skb_core thus
leading to unpleasant effects.

The solution is to pass skb by reference into __netif_receive_skb_core.

v2: Added Fixes tag and comment regarding ppt_prev and skb invariant.

Fixes: 88eb1944e18c ("net: core: propagate SKB lists through packet_type lookup")
Signed-off-by: Boris Sukholitko 
Acked-by: Edward Cree 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

flow_dissector: Drop BPF flow dissector prog ref on netns cleanup

2020-05-27T15:46:49+00:00

commit 5cf65922bb15279402e1e19b5ee8c51d618fa51f upstream.

When attaching a flow dissector program to a network namespace with
bpf(BPF_PROG_ATTACH, ...) we grab a reference to bpf_prog.

If netns gets destroyed while a flow dissector is still attached, and there
are no other references to the prog, we leak the reference and the program
remains loaded.

Leak can be reproduced by running flow dissector tests from selftests/bpf:

  # bpftool prog list
  # ./test_flow_dissector.sh
  ...
  selftests: test_flow_dissector [PASS]
  # bpftool prog list
  4: flow_dissector  name _dissect  tag e314084d332a5338  gpl
          loaded_at 2020-05-20T18:50:53+0200  uid 0
          xlated 552B  jited 355B  memlock 4096B  map_ids 3,4
          btf_id 4
  #

Fix it by detaching the flow dissector program when netns is going away.

Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook")
Signed-off-by: Jakub Sitnicki 
Signed-off-by: Alexei Starovoitov 
Reviewed-by: Stanislav Fomichev 
Link: https://lore.kernel.org/bpf/20200521083435.560256-1-jakub@cloudflare.com
Signed-off-by: Greg Kroah-Hartman