From: KP Singh <kpsingh@kernel.org>
To: Gilad Reti <gilad.reti@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Shuah Khan <shuah@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
linux-kselftest@vger.kernel.org,
Networking <netdev@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
Date: Tue, 12 Jan 2021 15:55:59 +0100 [thread overview]
Message-ID: <CACYkzJ69serkHRymzDEAcQ-_KAdHA+RxP4qpAwzGmppWUxYeQQ@mail.gmail.com> (raw)
In-Reply-To: <20210112091545.10535-1-gilad.reti@gmail.com>
On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com> wrote:
>
> Add test to check that the verifier is able to recognize spilling of
> PTR_TO_MEM registers.
>
It would be nice to have some explanation of what the test does to
recognize the spilling of the PTR_TO_MEM registers in the commit
log as well.
Would it be possible to augment an existing test_progs
program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
this functionality?
> The patch was partially contibuted by CyberArk Software, Inc.
>
> Signed-off-by: Gilad Reti <gilad.reti@gmail.com>
> ---
> tools/testing/selftests/bpf/test_verifier.c | 12 +++++++-
> .../selftests/bpf/verifier/spill_fill.c | 30 +++++++++++++++++++
> 2 files changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index 777a81404fdb..f8569f04064b 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -50,7 +50,7 @@
> #define MAX_INSNS BPF_MAXINSNS
> #define MAX_TEST_INSNS 1000000
> #define MAX_FIXUPS 8
> -#define MAX_NR_MAPS 20
> +#define MAX_NR_MAPS 21
> #define MAX_TEST_RUNS 8
> #define POINTER_VALUE 0xcafe4all
> #define TEST_DATA_LEN 64
> @@ -87,6 +87,7 @@ struct bpf_test {
> int fixup_sk_storage_map[MAX_FIXUPS];
> int fixup_map_event_output[MAX_FIXUPS];
> int fixup_map_reuseport_array[MAX_FIXUPS];
> + int fixup_map_ringbuf[MAX_FIXUPS];
> const char *errstr;
> const char *errstr_unpriv;
> uint32_t insn_processed;
> @@ -640,6 +641,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
> int *fixup_sk_storage_map = test->fixup_sk_storage_map;
> int *fixup_map_event_output = test->fixup_map_event_output;
> int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
> + int *fixup_map_ringbuf = test->fixup_map_ringbuf;
>
> if (test->fill_helper) {
> test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
> @@ -817,6 +819,14 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
> fixup_map_reuseport_array++;
> } while (*fixup_map_reuseport_array);
> }
> + if (*fixup_map_ringbuf) {
> + map_fds[20] = create_map(BPF_MAP_TYPE_RINGBUF, 0,
> + 0, 4096);
> + do {
> + prog[*fixup_map_ringbuf].imm = map_fds[20];
> + fixup_map_ringbuf++;
> + } while (*fixup_map_ringbuf);
> + }
> }
>
> struct libcap {
> diff --git a/tools/testing/selftests/bpf/verifier/spill_fill.c b/tools/testing/selftests/bpf/verifier/spill_fill.c
> index 45d43bf82f26..1833b6c730dd 100644
> --- a/tools/testing/selftests/bpf/verifier/spill_fill.c
> +++ b/tools/testing/selftests/bpf/verifier/spill_fill.c
> @@ -28,6 +28,36 @@
> .result = ACCEPT,
> .result_unpriv = ACCEPT,
> },
> +{
> + "check valid spill/fill, ptr to mem",
> + .insns = {
> + /* reserve 8 byte ringbuf memory */
> + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
> + BPF_LD_MAP_FD(BPF_REG_1, 0),
> + BPF_MOV64_IMM(BPF_REG_2, 8),
> + BPF_MOV64_IMM(BPF_REG_3, 0),
> + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
> + /* store a pointer to the reserved memory in R6 */
> + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
> + /* check whether the reservation was successful */
> + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6),
> + /* spill R6(mem) into the stack */
> + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
> + /* fill it back in R7 */
> + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, -8),
> + /* should be able to access *(R7) = 0 */
> + BPF_ST_MEM(BPF_DW, BPF_REG_7, 0, 0),
> + /* submit the reserved rungbuf memory */
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
> + BPF_MOV64_IMM(BPF_REG_2, 0),
> + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_submit),
> + BPF_MOV64_IMM(BPF_REG_0, 0),
> + BPF_EXIT_INSN(),
> + },
> + .fixup_map_ringbuf = { 1 },
> + .result = ACCEPT,
> + .result_unpriv = ACCEPT,
> +},
> {
> "check corrupted spill/fill",
> .insns = {
> --
> 2.27.0
>
next prev parent reply other threads:[~2021-01-12 14:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 9:15 [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill Gilad Reti
2021-01-12 14:55 ` KP Singh [this message]
2021-01-12 15:35 ` Gilad Reti
2021-01-12 15:43 ` Daniel Borkmann
2021-01-12 16:17 ` KP Singh
2021-01-12 16:24 ` Gilad Reti
2021-01-12 16:59 ` Yonghong Song
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