diff mbox series

[PATCHv2,bpf-next,08/11] selftests/bpf: Add tests for reference tracking

Message ID 20180921171043.20823-9-joe@wand.net.nz
State Changes Requested, archived
Delegated to: BPF Maintainers
Headers show
Series Add socket lookup support | expand

Commit Message

Joe Stringer Sept. 21, 2018, 5:10 p.m. UTC 
reference tracking: leak potential reference
reference tracking: leak potential reference on stack
reference tracking: leak potential reference on stack 2
reference tracking: zero potential reference
reference tracking: copy and zero potential references
reference tracking: release reference without check
reference tracking: release reference
reference tracking: release reference twice
reference tracking: release reference twice inside branch
reference tracking: alloc, check, free in one subbranch
reference tracking: alloc, check, free in both subbranches
reference tracking in call: free reference in subprog
reference tracking in call: free reference in subprog and outside
reference tracking in call: alloc & leak reference in subprog
reference tracking in call: alloc in subprog, release outside
reference tracking in call: sk_ptr leak into caller stack
reference tracking in call: sk_ptr spill into caller stack

Signed-off-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/testing/selftests/bpf/test_verifier.c | 359 ++++++++++++++++++++
 1 file changed, 359 insertions(+)

Comments

Daniel Borkmann Sept. 24, 2018, 12:21 p.m. UTC | #1 
On 09/21/2018 07:10 PM, Joe Stringer wrote:
> reference tracking: leak potential reference
> reference tracking: leak potential reference on stack
> reference tracking: leak potential reference on stack 2
> reference tracking: zero potential reference
> reference tracking: copy and zero potential references
> reference tracking: release reference without check
> reference tracking: release reference
> reference tracking: release reference twice
> reference tracking: release reference twice inside branch
> reference tracking: alloc, check, free in one subbranch
> reference tracking: alloc, check, free in both subbranches
> reference tracking in call: free reference in subprog
> reference tracking in call: free reference in subprog and outside
> reference tracking in call: alloc & leak reference in subprog
> reference tracking in call: alloc in subprog, release outside
> reference tracking in call: sk_ptr leak into caller stack
> reference tracking in call: sk_ptr spill into caller stack
> 
> Signed-off-by: Joe Stringer <joe@wand.net.nz>
> Acked-by: Alexei Starovoitov <ast@kernel.org>
> ---
>  tools/testing/selftests/bpf/test_verifier.c | 359 ++++++++++++++++++++
>  1 file changed, 359 insertions(+)

I think this here needs to have some more test cases that we current do not track but
should in order to have better coverage. At minimum what comes to mind additionally:

- verifier interaction with LD_ABS, LD_IND
- verifier interaction with tail calls (e.g. try to leak socket, socket_or_null, etc,
  but should also have a positive test where we drop ref before tail call to show it
  works in combination)
- Try to mangle a socket and socket_or_null pointer with ALU ops and pass it to helper
- Try to access the socket data fields after we released its reference
- Access socket member fields in general (I think not present right now)
- Use direct packet access in combination with lookup helper (it's enabled
  via pkt_access = true in the helper, so we should also test for it here to make
  sure future changes don't break it)
- ...
Joe Stringer Sept. 26, 2018, 10:31 p.m. UTC | #2 
On Mon, 24 Sep 2018 at 05:22, Daniel Borkmann <daniel@iogearbox.net> wrote:
>
> On 09/21/2018 07:10 PM, Joe Stringer wrote:
> > reference tracking: leak potential reference
> > reference tracking: leak potential reference on stack
> > reference tracking: leak potential reference on stack 2
> > reference tracking: zero potential reference
> > reference tracking: copy and zero potential references
> > reference tracking: release reference without check
> > reference tracking: release reference
> > reference tracking: release reference twice
> > reference tracking: release reference twice inside branch
> > reference tracking: alloc, check, free in one subbranch
> > reference tracking: alloc, check, free in both subbranches
> > reference tracking in call: free reference in subprog
> > reference tracking in call: free reference in subprog and outside
> > reference tracking in call: alloc & leak reference in subprog
> > reference tracking in call: alloc in subprog, release outside
> > reference tracking in call: sk_ptr leak into caller stack
> > reference tracking in call: sk_ptr spill into caller stack
> >
> > Signed-off-by: Joe Stringer <joe@wand.net.nz>
> > Acked-by: Alexei Starovoitov <ast@kernel.org>
> > ---
> >  tools/testing/selftests/bpf/test_verifier.c | 359 ++++++++++++++++++++
> >  1 file changed, 359 insertions(+)
>
> I think this here needs to have some more test cases that we current do not track but
> should in order to have better coverage. At minimum what comes to mind additionally:
>
> - verifier interaction with LD_ABS, LD_IND
> - verifier interaction with tail calls (e.g. try to leak socket, socket_or_null, etc,
>   but should also have a positive test where we drop ref before tail call to show it
>   works in combination)
> - Try to mangle a socket and socket_or_null pointer with ALU ops and pass it to helper
> - Try to access the socket data fields after we released its reference
> - Access socket member fields in general (I think not present right now)
> - Use direct packet access in combination with lookup helper (it's enabled
>   via pkt_access = true in the helper, so we should also test for it here to make
>   sure future changes don't break it)

Great suggestions, I think that the LD_ABS/LD_IND ones are good
candidates for the assembly-level tests here. For the remainder, I
plan to add them to the C cases. That'll be easier to review and
easier to understand if they ever get broken.

Regarding the direct packet access with lookup, that's already in this
series in the C verifier tests patch.
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index ceb55a9f3da9..eb760ead257a 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -3,6 +3,7 @@ 
  *
  * Copyright (c) 2014 PLUMgrid, http://plumgrid.com
  * Copyright (c) 2017 Facebook
+ * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of version 2 of the GNU General Public
@@ -177,6 +178,23 @@  static void bpf_fill_rand_ld_dw(struct bpf_test *self)
 	self->retval = (uint32_t)res;
 }
 
+#define BPF_SK_LOOKUP							\
+	/* struct bpf_sock_tuple tuple = {} */				\
+	BPF_MOV64_IMM(BPF_REG_2, 0),					\
+	BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -8),			\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -16),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -24),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -32),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -40),		\
+	BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -48),		\
+	/* sk = sk_lookup_tcp(ctx, &tuple, sizeof tuple, 0, 0) */	\
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),				\
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -48),				\
+	BPF_MOV64_IMM(BPF_REG_3, 44),					\
+	BPF_MOV64_IMM(BPF_REG_4, 0),					\
+	BPF_MOV64_IMM(BPF_REG_5, 0),					\
+	BPF_EMIT_CALL(BPF_FUNC_sk_lookup_tcp)
+
 static struct bpf_test tests[] = {
 	{
 		"add+sub+mul",
@@ -12441,6 +12459,222 @@  static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.result = ACCEPT,
 	},
+	{
+		"reference tracking: leak potential reference",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), /* leak reference */
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: leak potential reference on stack",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: leak potential reference on stack 2",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_ST_MEM(BPF_DW, BPF_REG_4, 0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: zero potential reference",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_IMM(BPF_REG_0, 0), /* leak reference */
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: copy and zero potential references",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_7, 0), /* leak reference */
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: release reference without check",
+		.insns = {
+			BPF_SK_LOOKUP,
+			/* reference in r0 may be NULL */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=sock_or_null expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: release reference",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: release reference 2",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+			BPF_EXIT_INSN(),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking: release reference twice",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=inv expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: release reference twice inside branch",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 4), /* goto end */
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=inv expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: alloc, check, free in one subbranch",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct __sk_buff, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct __sk_buff, data_end)),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 16),
+			/* if (offsetof(skb, mark) > data_len) exit; */
+			BPF_JMP_REG(BPF_JLE, BPF_REG_0, BPF_REG_3, 1),
+			BPF_EXIT_INSN(),
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_2,
+				    offsetof(struct __sk_buff, mark)),
+			BPF_SK_LOOKUP,
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 1), /* mark == 0? */
+			/* Leak reference in R0 */
+			BPF_EXIT_INSN(),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), /* sk NULL? */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking: alloc, check, free in both subbranches",
+		.insns = {
+			BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+				    offsetof(struct __sk_buff, data)),
+			BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+				    offsetof(struct __sk_buff, data_end)),
+			BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 16),
+			/* if (offsetof(skb, mark) > data_len) exit; */
+			BPF_JMP_REG(BPF_JLE, BPF_REG_0, BPF_REG_3, 1),
+			BPF_EXIT_INSN(),
+			BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_2,
+				    offsetof(struct __sk_buff, mark)),
+			BPF_SK_LOOKUP,
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 5), /* mark == 0? */
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), /* sk NULL? */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), /* sk NULL? */
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking in call: free reference in subprog",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), /* unchecked reference */
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_1),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_2, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
 	{
 		"pass modified ctx pointer to helper, 1",
 		.insns = {
@@ -12511,6 +12745,131 @@  static struct bpf_test tests[] = {
 		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
 		.result = ACCEPT,
 	},
+	{
+		"reference tracking in call: free reference in subprog and outside",
+		.insns = {
+			BPF_SK_LOOKUP,
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0), /* unchecked reference */
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_1),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_2, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "type=inv expected=sock",
+		.result = REJECT,
+	},
+	{
+		"reference tracking in call: alloc & leak reference in subprog",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 3),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_6, BPF_REG_4),
+			BPF_SK_LOOKUP,
+			/* spill unchecked sk_ptr into stack of caller */
+			BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_0, 0),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking in call: alloc in subprog, release outside",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 5),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_SK_LOOKUP,
+			BPF_EXIT_INSN(), /* return sk */
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.retval = POINTER_VALUE,
+		.result = ACCEPT,
+	},
+	{
+		"reference tracking in call: sk_ptr leak into caller stack",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_5, BPF_REG_4, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 5),
+			/* spill unchecked sk_ptr into stack of caller */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_5, 0),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 2 */
+			BPF_SK_LOOKUP,
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.errstr = "Unreleased reference",
+		.result = REJECT,
+	},
+	{
+		"reference tracking in call: sk_ptr spill into caller stack",
+		.insns = {
+			BPF_MOV64_REG(BPF_REG_4, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 2),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+
+			/* subprog 1 */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_STX_MEM(BPF_DW, BPF_REG_5, BPF_REG_4, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 1, 0, 9),
+			/* spill unchecked sk_ptr into stack of caller */
+			BPF_MOV64_REG(BPF_REG_5, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, -8),
+			BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_5, 0),
+			BPF_STX_MEM(BPF_DW, BPF_REG_4, BPF_REG_0, 0),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3),
+			/* now the sk_ptr is verified, free the reference */
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_4, 0),
+			BPF_MOV64_IMM(BPF_REG_2, 0),
+			BPF_EMIT_CALL(BPF_FUNC_sk_release),
+			BPF_EXIT_INSN(),
+
+			/* subprog 2 */
+			BPF_SK_LOOKUP,
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+		.result = ACCEPT,
+	},
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)