2024-01-15 08:22:56

by Hao Sun

Subject: [PATCH v4 2/2] selftests/bpf: Add test for alu on PTR_TO_FLOW_KEYS

Add a test case for PTR_TO_FLOW_KEYS alu. Testing if alu with
variable offset on flow_keys is rejected.

Signed-off-by: Hao Sun <[email protected]>
---
.../bpf/progs/verifier_value_illegal_alu.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c b/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c
index 71814a753216..a9ab37d3b9e2 100644
--- a/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c
+++ b/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c
@@ -146,4 +146,23 @@ l0_%=: exit; \
: __clobber_all);
}

+SEC("flow_dissector")
+__description("flow_keys illegal alu op with variable offset")
+__failure __msg("R7 pointer arithmetic on flow_keys prohibited")
+__naked void flow_keys_illegal_variable_offset_alu(void)
+{
+ asm volatile(" \
+ r6 = r1; \
+ r7 = *(u64*)(r6 + %[flow_keys_off]); \
+ r8 = 8; \
+ r8 /= 1; \
+ r8 &= 8; \
+ r7 += r8; \
+ r0 = *(u64*)(r7 + 0); \
+ exit; \
+" :
+ : __imm_const(flow_keys_off, offsetof(struct __sk_buff, flow_keys))
+ : __clobber_all);
+}
+
char _license[] SEC("license") = "GPL";
--
2.34.1

2024-01-15 17:35:37

by Yonghong Song

Subject: Re: [PATCH v4 2/2] selftests/bpf: Add test for alu on PTR_TO_FLOW_KEYS

On 1/15/24 12:20 AM, Hao Sun wrote:
> Add a test case for PTR_TO_FLOW_KEYS alu. Testing if alu with
> variable offset on flow_keys is rejected.
>
> Signed-off-by: Hao Sun <[email protected]>

Acked-by: Yonghong Song <[email protected]>

2024-01-16 16:36:24

by Daniel Borkmann

Subject: Re: [PATCH v4 2/2] selftests/bpf: Add test for alu on PTR_TO_FLOW_KEYS

On 1/15/24 9:20 AM, Hao Sun wrote:
> Add a test case for PTR_TO_FLOW_KEYS alu. Testing if alu with
> variable offset on flow_keys is rejected.
>
> Signed-off-by: Hao Sun <[email protected]>

Thanks applied, I've also added a note that we already have coverage
on the success case. Do you plan to follow up with checking the
remaining pointer types as Eduard suggested earlier?

Thanks,
Daniel

2024-01-16 16:49:09

by Hao Sun

Subject: Re: [PATCH v4 2/2] selftests/bpf: Add test for alu on PTR_TO_FLOW_KEYS

On Tue, Jan 16, 2024 at 5:20 PM Daniel Borkmann <[email protected]> wrote:
>
> On 1/15/24 9:20 AM, Hao Sun wrote:
> > Add a test case for PTR_TO_FLOW_KEYS alu. Testing if alu with
> > variable offset on flow_keys is rejected.
> >
> > Signed-off-by: Hao Sun <[email protected]>
>
> Thanks applied, I've also added a note that we already have coverage
> on the success case. Do you plan to follow up with checking the
> remaining pointer types as Eduard suggested earlier?
>

Yes, will do it in the following days.