diff mbox series

[v2,2/2] selftests/bpf: Add tests for alu on PTR_TO_FLOW_KEYS

Message ID 20240110125317.13742-2-sunhao.th@gmail.com
State New
Headers
Series [v2,1/2] bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS |

Commit Message

Hao Sun Jan. 10, 2024, 12:53 p.m. UTC 
  Add two cases for PTR_TO_FLOW_KEYS alu. One for rejecting alu with
variable offset, another for fixed offset.

Signed-off-by: Hao Sun <sunhao.th@gmail.com>
---
 .../bpf/progs/verifier_value_illegal_alu.c    | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

Comments

Hao Sun Jan. 10, 2024, 1:30 p.m. UTC | #1 
On Wed, Jan 10, 2024 at 1:53 PM Hao Sun <sunhao.th@gmail.com> wrote:
>
> Add two cases for PTR_TO_FLOW_KEYS alu. One for rejecting alu with
> variable offset, another for fixed offset.
>
> Signed-off-by: Hao Sun <sunhao.th@gmail.com>
> ---
>  .../bpf/progs/verifier_value_illegal_alu.c    | 37 +++++++++++++++++++
>  1 file changed, 37 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/verifier_value_illegal_aluc b/tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c
> index 71814a753216..49089361c98a 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 +146,41 @@ 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);
> +}
> +
> +SEC("flow_dissector")
> +__description("flow_keys valid alu op with fixed offset")
> +__success
> +__naked void flow_keys_legal_fixed_offset_alu(void)
> +{
> +       asm volatile("                                                  \
> +       r6 = r1;                                                                \
> +       r7 = *(u64*)(r6 + %[flow_keys_off]);    \
> +       r8 = 8;                                                                 \
> +       r7 += r8;                                                               \
> +       r0 = *(u64*)(r7 + 0);                                   \
> +       exit;                                                                   \
> +"      :
> +       : __imm_const(flow_keys_off, offsetof(struct __sk_buff, flow_keys))
> +       : __clobber_all);
> +}
> +

The format here is strange and should be fixed later.
I'm also curious, why only fixed-off is used in check_flow_keys_access()
for validation?
diff mbox series

Patch

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..49089361c98a 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 +146,41 @@  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);
+}
+
+SEC("flow_dissector")
+__description("flow_keys valid alu op with fixed offset")
+__success
+__naked void flow_keys_legal_fixed_offset_alu(void)
+{
+	asm volatile("							\
+	r6 = r1;								\
+	r7 = *(u64*)(r6 + %[flow_keys_off]);	\
+	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";