[PATCH bpf-next v6 13/13] selftests/bpf: Add test for strict BTF type check

[Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>]

Ensure that the edge case where first member type was matched
successfully even if it didn't match BTF type of register is caught and
rejected by the verifier.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
 net/bpf/test_run.c                           | 22 +++++++++++++++++++-
 tools/testing/selftests/bpf/verifier/calls.c | 20 ++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 29fe32821e7e..7a1579c91432 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -550,8 +550,13 @@ struct sock * noinline bpf_kfunc_call_test3(struct sock *sk)
 	return sk;
 }
 
+struct prog_test_member1 {
+	int a;
+};
+
 struct prog_test_member {
-	u64 c;
+	struct prog_test_member1 m;
+	int c;
 };
 
 struct prog_test_ref_kfunc {
@@ -576,6 +581,12 @@ bpf_kfunc_call_test_acquire(unsigned long *scalar_ptr)
 	return &prog_test_struct;
 }
 
+noinline struct prog_test_member *
+bpf_kfunc_call_memb_acquire(void)
+{
+	return &prog_test_struct.memb;
+}
+
 noinline void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p)
 {
 }
@@ -584,6 +595,10 @@ noinline void bpf_kfunc_call_memb_release(struct prog_test_member *p)
 {
 }
 
+noinline void bpf_kfunc_call_memb1_release(struct prog_test_member1 *p)
+{
+}
+
 noinline struct prog_test_ref_kfunc *
 bpf_kfunc_call_test_kptr_get(struct prog_test_ref_kfunc **p, int a, int b)
 {
@@ -673,8 +688,10 @@ BTF_ID(func, bpf_kfunc_call_test1)
 BTF_ID(func, bpf_kfunc_call_test2)
 BTF_ID(func, bpf_kfunc_call_test3)
 BTF_ID(func, bpf_kfunc_call_test_acquire)
+BTF_ID(func, bpf_kfunc_call_memb_acquire)
 BTF_ID(func, bpf_kfunc_call_test_release)
 BTF_ID(func, bpf_kfunc_call_memb_release)
+BTF_ID(func, bpf_kfunc_call_memb1_release)
 BTF_ID(func, bpf_kfunc_call_test_kptr_get)
 BTF_ID(func, bpf_kfunc_call_test_pass_ctx)
 BTF_ID(func, bpf_kfunc_call_test_pass1)
@@ -689,16 +706,19 @@ BTF_SET_END(test_sk_check_kfunc_ids)
 
 BTF_SET_START(test_sk_acquire_kfunc_ids)
 BTF_ID(func, bpf_kfunc_call_test_acquire)
+BTF_ID(func, bpf_kfunc_call_memb_acquire)
 BTF_ID(func, bpf_kfunc_call_test_kptr_get)
 BTF_SET_END(test_sk_acquire_kfunc_ids)
 
 BTF_SET_START(test_sk_release_kfunc_ids)
 BTF_ID(func, bpf_kfunc_call_test_release)
 BTF_ID(func, bpf_kfunc_call_memb_release)
+BTF_ID(func, bpf_kfunc_call_memb1_release)
 BTF_SET_END(test_sk_release_kfunc_ids)
 
 BTF_SET_START(test_sk_ret_null_kfunc_ids)
 BTF_ID(func, bpf_kfunc_call_test_acquire)
+BTF_ID(func, bpf_kfunc_call_memb_acquire)
 BTF_ID(func, bpf_kfunc_call_test_kptr_get)
 BTF_SET_END(test_sk_ret_null_kfunc_ids)
 
diff --git a/tools/testing/selftests/bpf/verifier/calls.c b/tools/testing/selftests/bpf/verifier/calls.c
index 2e03decb11b6..743ed34c1238 100644
--- a/tools/testing/selftests/bpf/verifier/calls.c
+++ b/tools/testing/selftests/bpf/verifier/calls.c
@@ -138,6 +138,26 @@
 		{ "bpf_kfunc_call_memb_release", 8 },
 	},
 },
+{
+	"calls: invalid kfunc call: don't match first member type when passed to release kfunc",
+	.insns = {
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+	BPF_EXIT_INSN(),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, BPF_PSEUDO_KFUNC_CALL, 0, 0),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.result = REJECT,
+	.errstr = "kernel function bpf_kfunc_call_memb1_release args#0 expected pointer",
+	.fixup_kfunc_btf_id = {
+		{ "bpf_kfunc_call_memb_acquire", 1 },
+		{ "bpf_kfunc_call_memb1_release", 5 },
+	},
+},
 {
 	"calls: invalid kfunc call: PTR_TO_BTF_ID with negative offset",
 	.insns = {
-- 
2.35.1