| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CANaYP3G_39cWx_L5Xs3tf1k4Vj9JSHcsr+qzNQN-dcY3qvT8Yg@mail.gmail.com>
Date: Tue, 12 Jan 2021 17:35:29 +0200
From: Gilad Reti <gilad.reti@...il.com>
To: KP Singh <kpsingh@...nel.org>
Cc: bpf <bpf@...r.kernel.org>, Shuah Khan <shuah@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
linux-kselftest@...r.kernel.org,
Networking <netdev@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@...nel.org> wrote:
>
> On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@...il.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?
>
It may be possible, but from what I understood from Daniel's comment here
https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@iogearbox.net/
the test should be a part of the verifier tests (which is reasonable
to me since it is
a verifier bugfix)
>
>
> > The patch was partially contibuted by CyberArk Software, Inc.
> >
> > Signed-off-by: Gilad Reti <gilad.reti@...il.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
> >
Powered by blists - more mailing lists