Add an enum (cgroup_bpf_attach_type) containing only valid cgroup_bpf
attach types and a function to map bpf_attach_type values to the new
enum. Inspired by netns_bpf_attach_type.

Then, migrate cgroup_bpf to use cgroup_bpf_attach_type wherever
possible.  Functionality is unchanged as attach_type_to_prog_type
switches in bpf/syscall.c were preventing non-cgroup programs from
making use of the invalid cgroup_bpf array slots.

As a result struct cgroup_bpf uses 504 fewer bytes relative to when its
arrays were sized using MAX_BPF_ATTACH_TYPE.

bpf_cgroup_storage is notably not migrated as struct
bpf_cgroup_storage_key is part of uapi and contains a bpf_attach_type
member which is not meant to be opaque. Similarly, bpf_cgroup_link
continues to report its bpf_attach_type member to userspace via fdinfo
and bpf_link_info.

To ease disambiguation, bpf_attach_type variables are renamed from
'type' to 'atype' when changed to cgroup_bpf_attach_type.
Signed-off-by: NDave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210819092420.1984861-2-davemarchevsky@fb.com

Commit 94531cfc ("af_unix: Add unix_stream_proto for sockmap")
introduced a bug for af_unix SEQPACKET type. In unix_shutdown, the
unhash function will call prot->unhash(), which is NULL for SEQPACKET.
And kernel will panic. On ARM32, it will show following messages: (it
likely affects x86 too).

Fix the bug by checking the prot->unhash is NULL or not first.

Kernel log:
<--- cut here ---
 Unable to handle kernel NULL pointer dereference at virtual address
00000000
 pgd = 2fba1ffb
 *pgd=00000000
 Internal error: Oops: 80000005 [#1] PREEMPT SMP THUMB2
 Modules linked in:
 CPU: 1 PID: 1999 Comm: falkon Tainted: G        W
5.14.0-rc5-01175-g94531cfc-dirty #9240
 Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
 PC is at 0x0
 LR is at unix_shutdown+0x81/0x1a8
 pc : [<00000000>]    lr : [<c08f3311>]    psr: 600f0013
 sp : e45aff70  ip : e463a3c0  fp : beb54f04
 r10: 00000125  r9 : e45ae000  r8 : c4a56664
 r7 : 00000001  r6 : c4a56464  r5 : 00000001  r4 : c4a56400
 r3 : 00000000  r2 : c5a6b180  r1 : 00000000  r0 : c4a56400
 Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
 Control: 50c5387d  Table: 05aa804a  DAC: 00000051
 Register r0 information: slab PING start c4a56400 pointer offset 0
 Register r1 information: NULL pointer
 Register r2 information: slab task_struct start c5a6b180 pointer offset 0
 Register r3 information: NULL pointer
 Register r4 information: slab PING start c4a56400 pointer offset 0
 Register r5 information: non-paged memory
 Register r6 information: slab PING start c4a56400 pointer offset 100
 Register r7 information: non-paged memory
 Register r8 information: slab PING start c4a56400 pointer offset 612
 Register r9 information: non-slab/vmalloc memory
 Register r10 information: non-paged memory
 Register r11 information: non-paged memory
 Register r12 information: slab filp start e463a3c0 pointer offset 0
 Process falkon (pid: 1999, stack limit = 0x9ec48895)
 Stack: (0xe45aff70 to 0xe45b0000)
 ff60:                                     e45ae000 c5f26a00 00000000 00000125
 ff80: c0100264 c07f7fa3 beb54f04 fffffff7 00000001 e6f3fc0e b5e5e9ec beb54ec4
 ffa0: b5da0ccc c010024b b5e5e9ec beb54ec4 0000000f 00000000 00000000 beb54ebc
 ffc0: b5e5e9ec beb54ec4 b5da0ccc 00000125 beb54f58 00785238 beb5529c beb54f04
 ffe0: b5da1e24 beb54eac b301385c b62b6ee8 600f0030 0000000f 00000000 00000000
 [<c08f3311>] (unix_shutdown) from [<c07f7fa3>] (__sys_shutdown+0x2f/0x50)
 [<c07f7fa3>] (__sys_shutdown) from [<c010024b>]
(__sys_trace_return+0x1/0x16)
 Exception stack(0xe45affa8 to 0xe45afff0)

Fixes: 94531cfc ("af_unix: Add unix_stream_proto for sockmap")
Reported-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Tested-by: NDmitry Osipenko <digetx@gmail.com>
Acked-by: NKuniyuki Iwashima <kuniyu@amazon.co.jp>
Link: https://lore.kernel.org/bpf/20210821180738.1151155-1-jiang.wang@bytedance.com

Adding selftests for the newly added functionality to call bpf_setsockopt()
and bpf_getsockopt() from setsockopt BPF programs.

Test Details:

1. BPF Program

   Checks for changes in IPV6_TCLASS(SOL_IPV6) via setsockopt
   If the cca for the socket is not cubic do nothing
   If the newly set value for IPV6_TCLASS is 45 (0x2d) (as per our use-case)
   then change the cc from cubic to reno

2. User Space Program

   Creates an AF_INET6 socket and set the cca for that to be "cubic"
   Attach the program and set the IPV6_TCLASS to 0x2d using setsockopt
   Verify the cca for the socket changed to reno
Signed-off-by: NPrankur Gupta <prankgup@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210817224221.3257826-3-prankgup@fb.com

Add logic to call bpf_setsockopt() and bpf_getsockopt() from setsockopt BPF
programs. An example use case is when the user sets the IPV6_TCLASS socket
option, we would also like to change the tcp-cc for that socket.

We don't have any use case for calling bpf_setsockopt() from supposedly read-
only sys_getsockopt(), so it is made available to BPF_CGROUP_SETSOCKOPT only
at this point.
Signed-off-by: NPrankur Gupta <prankgup@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210817224221.3257826-2-prankgup@fb.com

Same as previous patch but for the keys. memdup_bpfptr is renamed
to kvmemdup_bpfptr (and converted to kvmalloc).
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818235216.1159202-2-sdf@google.com

Use kvmalloc/kvfree for temporary value when manipulating a map via
syscall. kmalloc might not be sufficient for percpu maps where the value
is big (and further multiplied by hundreds of CPUs).

Can be reproduced with netcnt test on qemu with "-smp 255".
Signed-off-by: NStanislav Fomichev <sdf@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818235216.1159202-1-sdf@google.com

This patch adds a 1ms delay to reduce flakyness of the test.
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210819163609.2583758-1-fallentree@fb.com

Andrii reported that libbpf CI hit the following oops when
running selftest send_signal:
  [ 1243.160719] BUG: kernel NULL pointer dereference, address: 0000000000000030
  [ 1243.161066] #PF: supervisor read access in kernel mode
  [ 1243.161066] #PF: error_code(0x0000) - not-present page
  [ 1243.161066] PGD 0 P4D 0
  [ 1243.161066] Oops: 0000 [#1] PREEMPT SMP NOPTI
  [ 1243.161066] CPU: 1 PID: 882 Comm: new_name Tainted: G           O      5.14.0-rc5 #1
  [ 1243.161066] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
  [ 1243.161066] RIP: 0010:bpf_overflow_handler+0x9a/0x1e0
  [ 1243.161066] Code: 5a 84 c0 0f 84 06 01 00 00 be 66 02 00 00 48 c7 c7 6d 96 07 82 48 8b ab 18 05 00 00 e8 df 55 eb ff 66 90 48 8d 75 48 48 89 e7 <ff> 55 30 41 89 c4 e8 fb c1 f0 ff 84 c0 0f 84 94 00 00 00 e8 6e 0f
  [ 1243.161066] RSP: 0018:ffffc900000c0d80 EFLAGS: 00000046
  [ 1243.161066] RAX: 0000000000000002 RBX: ffff8881002e0dd0 RCX: 00000000b4b47cf8
  [ 1243.161066] RDX: ffffffff811dcb06 RSI: 0000000000000048 RDI: ffffc900000c0d80
  [ 1243.161066] RBP: 0000000000000000 R08: 0000000000000000 R09: 1a9d56bb00000000
  [ 1243.161066] R10: 0000000000000001 R11: 0000000000080000 R12: 0000000000000000
  [ 1243.161066] R13: ffffc900000c0e00 R14: ffffc900001c3c68 R15: 0000000000000082
  [ 1243.161066] FS:  00007fc0be2d3380(0000) GS:ffff88813bd00000(0000) knlGS:0000000000000000
  [ 1243.161066] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 1243.161066] CR2: 0000000000000030 CR3: 0000000104f8e000 CR4: 00000000000006e0
  [ 1243.161066] Call Trace:
  [ 1243.161066]  <IRQ>
  [ 1243.161066]  __perf_event_overflow+0x4f/0xf0
  [ 1243.161066]  perf_swevent_hrtimer+0x116/0x130
  [ 1243.161066]  ? __lock_acquire+0x378/0x2730
  [ 1243.161066]  ? __lock_acquire+0x372/0x2730
  [ 1243.161066]  ? lock_is_held_type+0xd5/0x130
  [ 1243.161066]  ? find_held_lock+0x2b/0x80
  [ 1243.161066]  ? lock_is_held_type+0xd5/0x130
  [ 1243.161066]  ? perf_event_groups_first+0x80/0x80
  [ 1243.161066]  ? perf_event_groups_first+0x80/0x80
  [ 1243.161066]  __hrtimer_run_queues+0x1a3/0x460
  [ 1243.161066]  hrtimer_interrupt+0x110/0x220
  [ 1243.161066]  __sysvec_apic_timer_interrupt+0x8a/0x260
  [ 1243.161066]  sysvec_apic_timer_interrupt+0x89/0xc0
  [ 1243.161066]  </IRQ>
  [ 1243.161066]  asm_sysvec_apic_timer_interrupt+0x12/0x20
  [ 1243.161066] RIP: 0010:finish_task_switch+0xaf/0x250
  [ 1243.161066] Code: 31 f6 68 90 2a 09 81 49 8d 7c 24 18 e8 aa d6 03 00 4c 89 e7 e8 12 ff ff ff 4c 89 e7 e8 ca 9c 80 00 e8 35 af 0d 00 fb 4d 85 f6 <58> 74 1d 65 48 8b 04 25 c0 6d 01 00 4c 3b b0 a0 04 00 00 74 37 f0
  [ 1243.161066] RSP: 0018:ffffc900001c3d18 EFLAGS: 00000282
  [ 1243.161066] RAX: 000000000000031f RBX: ffff888104cf4980 RCX: 0000000000000000
  [ 1243.161066] RDX: 0000000000000000 RSI: ffffffff82095460 RDI: ffffffff820adc4e
  [ 1243.161066] RBP: ffffc900001c3d58 R08: 0000000000000001 R09: 0000000000000001
  [ 1243.161066] R10: 0000000000000001 R11: 0000000000080000 R12: ffff88813bd2bc80
  [ 1243.161066] R13: ffff8881002e8000 R14: ffff88810022ad80 R15: 0000000000000000
  [ 1243.161066]  ? finish_task_switch+0xab/0x250
  [ 1243.161066]  ? finish_task_switch+0x70/0x250
  [ 1243.161066]  __schedule+0x36b/0xbb0
  [ 1243.161066]  ? _raw_spin_unlock_irqrestore+0x2d/0x50
  [ 1243.161066]  ? lockdep_hardirqs_on+0x79/0x100
  [ 1243.161066]  schedule+0x43/0xe0
  [ 1243.161066]  pipe_read+0x30b/0x450
  [ 1243.161066]  ? wait_woken+0x80/0x80
  [ 1243.161066]  new_sync_read+0x164/0x170
  [ 1243.161066]  vfs_read+0x122/0x1b0
  [ 1243.161066]  ksys_read+0x93/0xd0
  [ 1243.161066]  do_syscall_64+0x35/0x80
  [ 1243.161066]  entry_SYSCALL_64_after_hwframe+0x44/0xae

The oops can also be reproduced with the following steps:
  ./vmtest.sh -s
  # at qemu shell
  cd /root/bpf && while true; do ./test_progs -t send_signal

Further analysis showed that the failure is introduced with
commit b89fbfbb ("bpf: Implement minimal BPF perf link").
With the above commit, the following scenario becomes possible:
    cpu1                        cpu2
                                hrtimer_interrupt -> bpf_overflow_handler
    (due to closing link_fd)
    bpf_perf_link_release ->
    perf_event_free_bpf_prog ->
    perf_event_free_bpf_handler ->
      WRITE_ONCE(event->overflow_handler, event->orig_overflow_handler)
      event->prog = NULL
                                bpf_prog_run(event->prog, &ctx)

In the above case, the event->prog is NULL for bpf_prog_run, hence
causing oops.

To fix the issue, check whether event->prog is NULL or not. If it
is, do not call bpf_prog_run. This seems working as the above
reproducible step runs more than one hour and I didn't see any
failures.

Fixes: b89fbfbb ("bpf: Implement minimal BPF perf link")
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210819155209.1927994-1-yhs@fb.com

The BPF interpreter as well as x86-64 BPF JIT were both in line by allowing
up to 33 tail calls (however odd that number may be!). Recently, this was
changed for the interpreter to reduce it down to 32 with the assumption that
this should have been the actual limit "which is in line with the behavior of
the x86 JITs" according to b61a28cf ("bpf: Fix off-by-one in tail call
count limiting").

Paul recently reported:

  I'm a bit surprised by this because I had previously tested the tail call
  limit of several JIT compilers and found it to be 33 (i.e., allowing chains
  of up to 34 programs). I've just extended a test program I had to validate
  this again on the x86-64 JIT, and found a limit of 33 tail calls again [1].

  Also note we had previously changed the RISC-V and MIPS JITs to allow up to
  33 tail calls [2, 3], for consistency with other JITs and with the interpreter.
  We had decided to increase these two to 33 rather than decrease the other
  JITs to 32 for backward compatibility, though that probably doesn't matter
  much as I'd expect few people to actually use 33 tail calls.

  [1] https://github.com/pchaigno/tail-call-bench/commit/ae7887482985b4b1745c9b2ef7ff9ae506c82886
  [2] 96bc4432 ("bpf, riscv: Limit to 33 tail calls")
  [3] e49e6f6d ("bpf, mips: Limit to 33 tail calls")

Therefore, revert b61a28cf to re-align interpreter to limit a maximum of
33 tail calls. While it is unlikely to hit the limit for the vast majority,
programs in the wild could one way or another depend on this, so lets rather
be a bit more conservative, and lets align the small remainder of JITs to 33.
If needed in future, this limit could be slightly increased, but not decreased.

Fixes: b61a28cf ("bpf: Fix off-by-one in tail call count limiting")
Reported-by: NPaul Chaignon <paul@cilium.io>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAndrii Nakryiko <andrii@kernel.org>
Acked-by: NJohan Almbladh <johan.almbladh@anyfinetworks.com>
Acked-by: NYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/CAO5pjwTWrC0_dzTbTHFPSqDwA56aVH+4KFGVqdq8=ASs0MqZGQ@mail.gmail.com

Add test to use get_netns_cookie() from BPF_PROG_TYPE_SOCK_OPS.
Signed-off-by: NXu Liu <liuxu623@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818105820.91894-3-liuxu623@gmail.com

We'd like to be able to identify netns from sockops hooks to
accelerate local process communication form different netns.
Signed-off-by: NXu Liu <liuxu623@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818105820.91894-2-liuxu623@gmail.com

This patch renames a documentation libbpf.rst to index.rst. In order
for readthedocs.org to pick this file up and properly build the
documentation site.

It also changes the title type of the ABI subsection in the
naming convention doc. This is so that readthedocs.org doesn't treat this
section as a separate document.
Signed-off-by: NGrant Seltzer <grantseltzer@gmail.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210818151313.49992-1-grantseltzer@gmail.com

The variable allow is being initialized with a value that is never read, it
is being updated later on. The assignment is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817170842.495440-1-colin.king@canonical.com

Yonghong Song says:

====================

The bpf selftest send_signal() is flaky for its subtests trying to
send signals in softirq/nmi context. To reduce flakiness, the
signal-targetted process priority is boosted, which should minimize
preemption of that process and improve the possibility that
the underlying task in softirq/nmi context is the bpf_send_signal()
wanted task.

Patch #1 did a refactoring to use ASSERT_* instead of old CHECK macros.
Patch #2 did actual change of boosting priority.

Changelog:
  v1 -> v2:
    remove skip logic where the underlying task in interrupt context
    is not the intended one.
====================
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>

libbpf CI has reported send_signal test is flaky although
I am not able to reproduce it in my local environment.
But I am able to reproduce with on-demand libbpf CI ([1]).

Through code analysis, the following is possible reason.
The failed subtest runs bpf program in softirq environment.
Since bpf_send_signal() only sends to a fork of "test_progs"
process. If the underlying current task is
not "test_progs", bpf_send_signal() will not be triggered
and the subtest will fail.

To reduce the chances where the underlying process is not
the intended one, this patch boosted scheduling priority to
-20 (highest allowed by setpriority() call). And I did
10 runs with on-demand libbpf CI with this patch and I
didn't observe any failures.

 [1] https://github.com/libbpf/libbpf/actions/workflows/ondemand.ymlSigned-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817190923.3186725-1-yhs@fb.com

Replace CHECK in send_signal.c with ASSERT_* macros as
ASSERT_* macros are generally preferred. There is no
funcitonality change.
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817190918.3186400-1-yhs@fb.com

Yucong Sun says:

====================

This short series adds two new switches to test_progs, "-a" and "-d",
adding support for both exact string matching, as well as '*' wildcards.
It also cleans up the output to make it possible to generate
allowlist/denylist using common cli tools.
====================
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>

This patch adds '-a' and '-d' arguments supporting both exact string match as
well as using '*' wildcard in test/subtests selection. '-a' and '-t' can
co-exists, same as '-d' and '-b', in which case they just add to the list of
allowed or denied test selectors.

Caveat: Same as the current substring matching mechanism, test and subtest
selector applies independently, 'a*/b*' will execute all tests matching "a*",
and with subtest name matching "b*", but tests matching "a*" that has no
subtests will also be executed.
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817044732.3263066-5-fallentree@fb.com

This patch add test name in subtest status message line, making it possible to
grep ':OK' in the output to generate a list of passed test+subtest names, which
can be processed to generate argument list to be used with "-a", "-d" exact
string matching.

Example:

 #1/1 align/mov:OK
 ..
 #1/12 align/pointer variable subtraction:OK
 #1 align:OK
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817044732.3263066-4-fallentree@fb.com

In skip_account(), test->skip_cnt is set to 0 at the end, this makes next print
statement never display SKIP status for the subtest. This patch moves the
accounting logic after the print statement, fixing the issue.

This patch also added SKIP status display for normal tests.
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817044732.3263066-3-fallentree@fb.com

When using "-l", test_progs often is executed as non-root user,
load_bpf_testmod() will fail and output errors. This patch skips loading bpf
testmod when "-l" is specified, making output cleaner.
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817044732.3263066-2-fallentree@fb.com

Using a fixed delay of 1 microsecond has proven flaky in slow CPU environment,
e.g. Github Actions CI system. This patch adds exponential backoff with a cap
of 50ms to reduce the flakiness of the test. Initial delay is chosen at random
in the range [0ms, 5ms).
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817045713.3307985-1-fallentree@fb.com

Using a fixed delay of 1 microsecond has proven flaky in slow CPU environment,
e.g. Github Actions CI system. This patch adds exponential backoff with a cap
of 50ms to reduce the flakiness of the test. Initial delay is chosen at random
in the range [0ms, 5ms).
Signed-off-by: NYucong Sun <fallentree@fb.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210816175250.296110-1-fallentree@fb.com

Jiang Wang says:

====================

This patch series add support for unix stream type
for sockmap. Sockmap already supports TCP, UDP,
unix dgram types. The unix stream support is similar
to unix dgram.

Also add selftests for unix stream type in sockmap tests.
====================
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>

Add two new test cases in sockmap tests, where unix stream is
redirected to tcp and vice versa.
Signed-off-by: NJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Reviewed-by: NCong Wang <cong.wang@bytedance.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210816190327.2739291-6-jiang.wang@bytedance.com

This is to prepare for adding new unix stream tests.
Mostly renames, also pass the socket types as an argument.
Signed-off-by: NJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Reviewed-by: NCong Wang <cong.wang@bytedance.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210816190327.2739291-5-jiang.wang@bytedance.com

Add two tests for unix stream to unix stream redirection
in sockmap tests.
Signed-off-by: NJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Reviewed-by: NCong Wang <cong.wang@bytedance.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210816190327.2739291-4-jiang.wang@bytedance.com

Previously, sockmap for AF_UNIX protocol only supports
dgram type. This patch add unix stream type support, which
is similar to unix_dgram_proto. To support sockmap, dgram
and stream cannot share the same unix_proto anymore, because
they have different implementations, such as unhash for stream
type (which will remove closed or disconnected sockets from the map),
so rename unix_proto to unix_dgram_proto and add a new
unix_stream_proto.

Also implement stream related sockmap functions.
And add dgram key words to those dgram specific functions.
Signed-off-by: NJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Reviewed-by: NCong Wang <cong.wang@bytedance.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210816190327.2739291-3-jiang.wang@bytedance.com

To support sockmap for af_unix stream type, implement
read_sock, which is similar to the read_sock for unix
dgram sockets.
Signed-off-by: NJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Reviewed-by: NCong Wang <cong.wang@bytedance.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210816190327.2739291-2-jiang.wang@bytedance.com

Add test for btf__load_vmlinux_btf/btf__load_module_btf APIs. The test
loads bpf_testmod module BTF and check existence of a symbol which is
known to exist.
Signed-off-by: NHengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210815081035.205879-1-hengqi.chen@gmail.com

This removes the libbpf_api.rst file from the kernel documentation.
The intention for this file was to pull documentation from comments
above API functions in libbpf. However, due to limitations of the
kernel documentation system, this API documentation could not be
versioned, which is counterintuative to how users expect to use it.
There is also currently no doc comments, making this a blank page.

Once the kernel comment documentation is actually contributed, it
will still exist in the kernel repository, just in the code itself.

A seperate site is being spun up to generate documentaiton from those
comments in a way in which it can be versioned properly.

This also reconfigures the bpf documentation index page to make it
easier to sync to the previously mentioned documentaiton site.
Signed-off-by: NGrant Seltzer <grantseltzer@gmail.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210810020508.280639-1-grantseltzer@gmail.com

Andrii Nakryiko says:

====================
This patch set implements an ability for users to specify custom black box u64
value for each BPF program attachment, bpf_cookie, which is available to BPF
program at runtime. This is a feature that's critically missing for cases when
some sort of generic processing needs to be done by the common BPF program
logic (or even exactly the same BPF program) across multiple BPF hooks (e.g.,
many uniformly handled kprobes) and it's important to be able to distinguish
between each BPF hook at runtime (e.g., for additional configuration lookup).

The choice of restricting this to a fixed-size 8-byte u64 value is an explicit
design decision. Making this configurable by users adds unnecessary complexity
(extra memory allocations, extra complications on the verifier side to validate
accesses to variable-sized data area) while not really opening up new
possibilities. If user's use case requires storing more data per attachment,
it's possible to use either global array, or ARRAY/HASHMAP BPF maps, where
bpf_cookie would be used as an index into respective storage, populated by
user-space code before creating BPF link. This gives user all the flexibility
and control while keeping BPF verifier and BPF helper API simple.

Currently, similar functionality can only be achieved through:

  - code-generation and BPF program cloning, which is very complicated and
    unmaintainable;
  - on-the-fly C code generation and further runtime compilation, which is
    what BCC uses and allows to do pretty simply. The big downside is a very
    heavy-weight Clang/LLVM dependency and inefficient memory usage (due to
    many BPF program clones and the compilation process itself);
  - in some cases (kprobes and sometimes uprobes) it's possible to do function
    IP lookup to get function-specific configuration. This doesn't work for
    all the cases (e.g., when attaching uprobes to shared libraries) and has
    higher runtime overhead and additional programming complexity due to
    BPF_MAP_TYPE_HASHMAP lookups. Up until recently, before bpf_get_func_ip()
    BPF helper was added, it was also very complicated and unstable (API-wise)
    to get traced function's IP from fentry/fexit and kretprobe.

With libbpf and BPF CO-RE, runtime compilation is not an option, so to be able
to build generic tracing tooling simply and efficiently, ability to provide
additional bpf_cookie value for each *attachment* (as opposed to each BPF
program) is extremely important. Two immediate users of this functionality are
going to be libbpf-based USDT library (currently in development) and retsnoop
([0]), but I'm sure more applications will come once users get this feature in
their kernels.

To achieve above described, all perf_event-based BPF hooks are made available
through a new BPF_LINK_TYPE_PERF_EVENT BPF link, which allows to use common
LINK_CREATE command for program attachments and generally brings
perf_event-based attachments into a common BPF link infrastructure.

With that, LINK_CREATE gets ability to pass throught bpf_cookie value during
link creation (BPF program attachment) time. bpf_get_attach_cookie() BPF
helper is added to allow fetching this value at runtime from BPF program side.
BPF cookie is stored either on struct perf_event itself and fetched from the
BPF program context, or is passed through ambient BPF run context, added in
c7603cfa ("bpf: Add ambient BPF runtime context stored in current").

On the libbpf side of things, BPF perf link is utilized whenever is supported
by the kernel instead of using PERF_EVENT_IOC_SET_BPF ioctl on perf_event FD.
All the tracing attach APIs are extended with OPTS and bpf_cookie is passed
through corresponding opts structs.

Last part of the patch set adds few self-tests utilizing new APIs.

There are also a few refactorings along the way to make things cleaner and
easier to work with, both in kernel (BPF_PROG_RUN and BPF_PROG_RUN_ARRAY), and
throughout libbpf and selftests.

Follow-up patches will extend bpf_cookie to fentry/fexit programs.

While adding uprobe_opts, also extend it with ref_ctr_offset for specifying
USDT semaphore (reference counter) offset. Update attach_probe selftests to
validate its functionality. This is another feature (along with bpf_cookie)
required for implementing libbpf-based USDT solution.

  [0] https://github.com/anakryiko/retsnoop

v4->v5:
  - rebase on latest bpf-next to resolve merge conflict;
  - add ref_ctr_offset to uprobe_opts and corresponding selftest;
v3->v4:
  - get rid of BPF_PROG_RUN macro in favor of bpf_prog_run() (Daniel);
  - move #ifdef CONFIG_BPF_SYSCALL check into bpf_set_run_ctx (Daniel);
v2->v3:
  - user_ctx -> bpf_cookie, bpf_get_user_ctx -> bpf_get_attach_cookie (Peter);
  - fix BPF_LINK_TYPE_PERF_EVENT value fix (Jiri);
  - use bpf_prog_run() from bpf_prog_run_pin_on_cpu() (Yonghong);
v1->v2:
  - fix build failures on non-x86 arches by gating on CONFIG_PERF_EVENTS.
====================
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Extend attach_probe selftests to specify ref_ctr_offset for uprobe/uretprobe
and validate that its value is incremented from zero.

Turns out that once uprobe is attached with ref_ctr_offset, uretprobe for the
same location/function *has* to use ref_ctr_offset as well, otherwise
perf_event_open() fails with -EINVAL. So this test uses ref_ctr_offset for
both uprobe and uretprobe, even though for the purpose of test uprobe would be
enough.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-17-andrii@kernel.org

When attaching to uprobes through perf subsystem, it's possible to specify
offset of a so-called USDT semaphore, which is just a reference counted u16,
used by kernel to keep track of how many tracers are attached to a given
location. Support for this feature was added in [0], so just wire this through
uprobe_opts. This is important to enable implementing USDT attachment and
tracing through libbpf's bpf_program__attach_uprobe_opts() API.

  [0] a6ca88b2 ("trace_uprobe: support reference counter in fd-based uprobe")
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-16-andrii@kernel.org

Add selftest with few subtests testing proper bpf_cookie usage.

Kprobe and uprobe subtests are pretty straightforward and just validate that
the same BPF program attached with different bpf_cookie will be triggered with
those different bpf_cookie values.

Tracepoint subtest is a bit more interesting, as it is the only
perf_event-based BPF hook that shares bpf_prog_array between multiple
perf_events internally. This means that the same BPF program can't be attached
to the same tracepoint multiple times. So we have 3 identical copies. This
arrangement allows to test bpf_prog_array_copy()'s handling of bpf_prog_array
list manipulation logic when programs are attached and detached.  The test
validates that bpf_cookie isn't mixed up and isn't lost during such list
manipulations.

Perf_event subtest validates that two BPF links can be created against the
same perf_event (but not at the same time, only one BPF program can be
attached to perf_event itself), and that for each we can specify different
bpf_cookie value.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-15-andrii@kernel.org

Extract two helpers used for working with uprobes into trace_helpers.{c,h} to
be re-used between multiple uprobe-using selftests. Also rename get_offset()
into more appropriate get_uprobe_offset().
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-14-andrii@kernel.org

Add tests utilizing low-level bpf_link_create() API to create perf BPF link.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-13-andrii@kernel.org

Wire through bpf_cookie for all attach APIs that use perf_event_open under the
hood:
  - for kprobes, extend existing bpf_kprobe_opts with bpf_cookie field;
  - for perf_event, uprobe, and tracepoint APIs, add their _opts variants and
    pass bpf_cookie through opts.

For kernel that don't support BPF_LINK_CREATE for perf_events, and thus
bpf_cookie is not supported either, return error and log warning for user.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-12-andrii@kernel.org

Add ability to specify bpf_cookie value when creating BPF perf link with
bpf_link_create() low-level API.

Given BPF_LINK_CREATE command is growing and keeps getting new fields that are
specific to the type of BPF_LINK, extend libbpf side of bpf_link_create() API
and corresponding OPTS struct to accomodate such changes. Add extra checks to
prevent using incompatible/unexpected combinations of fields.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-11-andrii@kernel.org

Detect kernel support for BPF perf link and prefer it when attaching to
perf_event, tracepoint, kprobe/uprobe. Underlying perf_event FD will be kept
open until BPF link is destroyed, at which point both perf_event FD and BPF
link FD will be closed.

This preserves current behavior in which perf_event FD is open for the
duration of bpf_link's lifetime and user is able to "disconnect" bpf_link from
underlying FD (with bpf_link__disconnect()), so that bpf_link__destroy()
doesn't close underlying perf_event FD.When BPF perf link is used, disconnect
will keep both perf_event and bpf_link FDs open, so it will be up to
(advanced) user to close them. This approach is demonstrated in bpf_cookie.c
selftests, added in this patch set.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-10-andrii@kernel.org