| Message ID | 20210112091545.10535-1-gilad.reti@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | None | expand |
On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote: > > 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? > 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@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 > >
On Tue, Jan 12, 2021 at 4:43 PM Daniel Borkmann <daniel@iogearbox.net> wrote: > > On 1/12/21 4:35 PM, Gilad Reti wrote: > > On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote: > >> 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? > > How would you guarantee that LLVM generates the spill/fill, via inline asm? Yeah, I guess there is no sure-shot way to do it and, adding inline asm would just be doing the same thing as this verifier test. You can ignore me on this one :) It would, however, be nice to have a better description about what the test is actually doing./ > > > 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) > > Yeah, the test_verifier case as you have is definitely the most straight > forward way to add coverage in this case.
On 1/12/21 7:43 AM, Daniel Borkmann wrote: > On 1/12/21 4:35 PM, Gilad Reti wrote: >> On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote: >>> 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? > > How would you guarantee that LLVM generates the spill/fill, via inline asm? You can make the following change to force the return value ("sample" here) of bpf_ringbuf_reserve() to spill on the stack. diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf.c b/tools/testing/selftests/bpf/progs/test_ringbuf.c index 8ba9959b036b..011521170856 100644 --- a/tools/testing/selftests/bpf/progs/test_ringbuf.c +++ b/tools/testing/selftests/bpf/progs/test_ringbuf.c @@ -40,7 +40,7 @@ SEC("tp/syscalls/sys_enter_getpgid") int test_ringbuf(void *ctx) { int cur_pid = bpf_get_current_pid_tgid() >> 32; - struct sample *sample; + struct sample * volatile sample; int zero = 0; if (cur_pid != pid) This change will cause verifier failure without Patch #1. > >> 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) > > Yeah, the test_verifier case as you have is definitely the most straight > forward way to add coverage in this case.
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 = {
Add test to check that the verifier is able to recognize spilling of PTR_TO_MEM registers. 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(-)