9 Commits

Author SHA1 Message Date
Kumar Kartikeya Dwivedi
4656569643 selftests/bpf: Add test for race in btf_try_get_module
This adds a complete test case to ensure we never take references to
modules not in MODULE_STATE_LIVE, which can lead to UAF, and it also
ensures we never access btf->kfunc_set_tab in an inconsistent state.

The test uses userfaultfd to artificially widen the race.

When run on an unpatched kernel, it leads to the following splat:

[root@(none) bpf]# ./test_progs -t bpf_mod_race/ksym
[   55.498171] BUG: unable to handle page fault for address: fffffbfff802548b
[   55.499206] #PF: supervisor read access in kernel mode
[   55.499855] #PF: error_code(0x0000) - not-present page
[   55.500555] PGD a4fa9067 P4D a4fa9067 PUD a4fa5067 PMD 1b44067 PTE 0
[   55.501499] Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
[   55.502195] CPU: 0 PID: 83 Comm: kworker/0:2 Tainted: G           OE     5.16.0-rc4+ #151
[   55.503388] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.15.0-1 04/01/2014
[   55.504777] Workqueue: events bpf_prog_free_deferred
[   55.505563] RIP: 0010:kasan_check_range+0x184/0x1d0
[   55.509140] RSP: 0018:ffff88800560fcf0 EFLAGS: 00010282
[   55.509977] RAX: fffffbfff802548b RBX: fffffbfff802548c RCX: ffffffff9337b6ba
[   55.511096] RDX: fffffbfff802548c RSI: 0000000000000004 RDI: ffffffffc012a458
[   55.512143] RBP: fffffbfff802548b R08: 0000000000000001 R09: ffffffffc012a45b
[   55.513228] R10: fffffbfff802548b R11: 0000000000000001 R12: ffff888001b5f598
[   55.514332] R13: ffff888004f49ac8 R14: 0000000000000000 R15: ffff888092449400
[   55.515418] FS:  0000000000000000(0000) GS:ffff888092400000(0000) knlGS:0000000000000000
[   55.516705] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   55.517560] CR2: fffffbfff802548b CR3: 0000000007c10006 CR4: 0000000000770ef0
[   55.518672] PKRU: 55555554
[   55.519022] Call Trace:
[   55.519483]  <TASK>
[   55.519884]  module_put.part.0+0x2a/0x180
[   55.520642]  bpf_prog_free_deferred+0x129/0x2e0
[   55.521478]  process_one_work+0x4fa/0x9e0
[   55.522122]  ? pwq_dec_nr_in_flight+0x100/0x100
[   55.522878]  ? rwlock_bug.part.0+0x60/0x60
[   55.523551]  worker_thread+0x2eb/0x700
[   55.524176]  ? __kthread_parkme+0xd8/0xf0
[   55.524853]  ? process_one_work+0x9e0/0x9e0
[   55.525544]  kthread+0x23a/0x270
[   55.526088]  ? set_kthread_struct+0x80/0x80
[   55.526798]  ret_from_fork+0x1f/0x30
[   55.527413]  </TASK>
[   55.527813] Modules linked in: bpf_testmod(OE) [last unloaded: bpf_testmod]
[   55.530846] CR2: fffffbfff802548b
[   55.531341] ---[ end trace 1af41803c054ad6d ]---
[   55.532136] RIP: 0010:kasan_check_range+0x184/0x1d0
[   55.535887] RSP: 0018:ffff88800560fcf0 EFLAGS: 00010282
[   55.536711] RAX: fffffbfff802548b RBX: fffffbfff802548c RCX: ffffffff9337b6ba
[   55.537821] RDX: fffffbfff802548c RSI: 0000000000000004 RDI: ffffffffc012a458
[   55.538899] RBP: fffffbfff802548b R08: 0000000000000001 R09: ffffffffc012a45b
[   55.539928] R10: fffffbfff802548b R11: 0000000000000001 R12: ffff888001b5f598
[   55.541021] R13: ffff888004f49ac8 R14: 0000000000000000 R15: ffff888092449400
[   55.542108] FS:  0000000000000000(0000) GS:ffff888092400000(0000) knlGS:0000000000000000
[   55.543260]CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   55.544136] CR2: fffffbfff802548b CR3: 0000000007c10006 CR4: 0000000000770ef0
[   55.545317] PKRU: 55555554
[   55.545671] note: kworker/0:2[83] exited with preempt_count 1

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220114163953.1455836-11-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-01-18 14:27:39 -08:00
Kumar Kartikeya Dwivedi
b202d84422 bpf: Remove check_kfunc_call callback and old kfunc BTF ID API
Completely remove the old code for check_kfunc_call to help it work
with modules, and also the callback itself.

The previous commit adds infrastructure to register all sets and put
them in vmlinux or module BTF, and concatenates all related sets
organized by the hook and the type. Once populated, these sets remain
immutable for the lifetime of the struct btf.

Also, since we don't need the 'owner' module anywhere when doing
check_kfunc_call, drop the 'btf_modp' module parameter from
find_kfunc_desc_btf.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220114163953.1455836-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-01-18 14:26:41 -08:00
Alexei Starovoitov
7edc3fcbf9 selftest/bpf: Add a test that reads various addresses.
Add a function to bpf_testmod that returns invalid kernel and user addresses.
Then attach an fexit program to that function that tries to read
memory through these addresses.

This logic checks that bpf_probe_read_kernel and BPF_PROBE_MEM logic is sane.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2021-12-16 21:41:13 +01:00
Hou Tao
fa7f17d066 bpf/selftests: Add test for writable bare tracepoint
Add a writable bare tracepoint in bpf_testmod module, and
trigger its calling when reading /sys/kernel/bpf_testmod
with a specific buffer length. The reading will return
the value in writable context if the early return flag
is enabled in writable context.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211004094857.30868-4-hotforest@gmail.com
2021-10-08 13:22:57 -07:00
Kumar Kartikeya Dwivedi
c48e51c8b0 bpf: selftests: Add selftests for module kfunc support
This adds selftests that tests the success and failure path for modules
kfuncs (in presence of invalid kfunc calls) for both libbpf and
gen_loader. It also adds a prog_test kfunc_btf_id_list so that we can
add module BTF ID set from bpf_testmod.

This also introduces  a couple of test cases to verifier selftests for
validating whether we get an error or not depending on if invalid kfunc
call remains after elimination of unreachable instructions.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-10-memxor@gmail.com
2021-10-05 17:07:42 -07:00
Song Liu
025bd7c753 selftests/bpf: Add test for bpf_get_branch_snapshot
This test uses bpf_get_branch_snapshot from a fexit program. The test uses
a target function (bpf_testmod_loop_test) and compares the record against
kallsyms. If there isn't enough record matching kallsyms, the test fails.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210910183352.3151445-4-songliubraving@fb.com
2021-09-13 10:53:50 -07:00
Qais Yousef
407be92206 selftests: bpf: Add a new test for bare tracepoints
Reuse module_attach infrastructure to add a new bare tracepoint to check
we can attach to it as a raw tracepoint.

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210119122237.2426878-3-qais.yousef@arm.com
2021-01-20 14:14:05 -08:00
Andrii Nakryiko
430d97a8a7 selftests/bpf: Test kernel module ksym externs
Add per-CPU variable to bpf_testmod.ko and use those from new selftest to
validate it works end-to-end.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/20210112075520.4103414-8-andrii@kernel.org
2021-01-12 17:24:30 -08:00
Andrii Nakryiko
9f7fa22589 selftests/bpf: Add bpf_testmod kernel module for testing
Add bpf_testmod module, which is conceptually out-of-tree module and provides
ways for selftests/bpf to test various kernel module-related functionality:
raw tracepoint, fentry/fexit/fmod_ret, etc. This module will be auto-loaded by
test_progs test runner and expected by some of selftests to be present and
loaded.

Pahole currently isn't able to generate BTF for static functions in kernel
modules, so make sure traced function is global.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-7-andrii@kernel.org
2020-12-03 17:38:20 -08:00