[PATCH bpf-next 2/2] bpf: btf: Ensure t->type == 0 for BTF_KIND_FWD

Martin KaFai Lau
2018-06-02T16:06:56Z

The t->type in BTF_KIND_FWD is not used. It must be 0.
This patch ensures that and also adds a test case in test_btf.c

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
kernel/bpf/btf.c | 21 ++++++++++++++++++++-
tools/testing/selftests/bpf/test_btf.c | 22 ++++++++++++++++++++++
2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 84ad532f2854..8653ab004c73 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1286,8 +1286,27 @@ static struct btf_kind_operations ptr_ops = {
.seq_show = btf_ptr_seq_show,
};

+static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
+ const struct btf_type *t,
+ u32 meta_left)
+{
+ if (btf_type_vlen(t)) {
+ btf_verifier_log_type(env, t, "vlen != 0");
+ return -EINVAL;
+ }
+
+ if (t->type) {
+ btf_verifier_log_type(env, t, "type != 0");
+ return -EINVAL;
+ }
+
+ btf_verifier_log_type(env, t, NULL);
+
+ return 0;
+}
+
static struct btf_kind_operations fwd_ops = {
- .check_meta = btf_ref_type_check_meta,
+ .check_meta = btf_fwd_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_df_check_member,
.log_details = btf_ref_type_log,
diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index fd8246e84149..3619f3023088 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -1242,6 +1242,28 @@ static struct btf_raw_test raw_tests[] = {
.err_str = "Invalid btf_info",
},

+{
+ .descr = "fwd test. t->type != 0\"",
+ .raw_types = {
+ /* int */ /* [1] */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+ /* fwd type */ /* [2] */
+ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FWD, 0, 0), 1),
+ BTF_END_RAW,
+ },
+ .str_sec = "",
+ .str_sec_size = sizeof(""),
+ .map_type = BPF_MAP_TYPE_ARRAY,
+ .map_name = "fwd_test_map",
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ .key_type_id = 1,
+ .value_type_id = 1,
+ .max_entries = 4,
+ .btf_load_err = true,
+ .err_str = "type != 0",
+},
+
}; /* struct btf_raw_test raw_tests[] */

static const char *get_next_str(const char *start, const char *end)
--
2.9.5