[PATCH 4.19 134/243] bpf: btf: check name validity for various types

Greg Kroah-Hartman
2019-12-11T15:51:54Z

From: Yonghong Song <yhs@fb.com>

[ Upstream commit eb04bbb608e683f8fd3ef7f716e2fa32dd90861f ]

This patch added name checking for the following types:
. BTF_KIND_PTR, BTF_KIND_ARRAY, BTF_KIND_VOLATILE,
BTF_KIND_CONST, BTF_KIND_RESTRICT:
the name must be null
. BTF_KIND_STRUCT, BTF_KIND_UNION: the struct/member name
is either null or a valid identifier
. BTF_KIND_ENUM: the enum type name is either null or a valid
identifier; the enumerator name must be a valid identifier.
. BTF_KIND_FWD: the name must be a valid identifier
. BTF_KIND_TYPEDEF: the name must be a valid identifier

For those places a valid name is required, the name must be
a valid C identifier. This can be relaxed later if we found
use cases for a different (non-C) frontend.

Fixes: 69b693f0aefa ("bpf: btf: Introduce BPF Type Format (BTF)")
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/btf.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index f0f9109f59bac..3e2413345e718 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1168,6 +1168,22 @@ static int btf_ref_type_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* typedef type must have a valid name, and other ref types,
+ * volatile, const, restrict, should have a null name.
+ */
+ if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
+ if (!t->name_off ||
+ !btf_name_valid_identifier(env->btf, t->name_off)) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+ } else {
+ if (t->name_off) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+ }
+
btf_verifier_log_type(env, t, NULL);

return 0;
@@ -1325,6 +1341,13 @@ static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* fwd type must have a valid name */
+ if (!t->name_off ||
+ !btf_name_valid_identifier(env->btf, t->name_off)) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+
btf_verifier_log_type(env, t, NULL);

return 0;
@@ -1381,6 +1404,12 @@ static s32 btf_array_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* array type should not have a name */
+ if (t->name_off) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
@@ -1557,6 +1586,13 @@ static s32 btf_struct_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* struct type either no name or a valid one */
+ if (t->name_off &&
+ !btf_name_valid_identifier(env->btf, t->name_off)) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+
btf_verifier_log_type(env, t, NULL);

last_offset = 0;
@@ -1568,6 +1604,12 @@ static s32 btf_struct_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* struct member either no name or a valid one */
+ if (member->name_off &&
+ !btf_name_valid_identifier(btf, member->name_off)) {
+ btf_verifier_log_member(env, t, member, "Invalid name");
+ return -EINVAL;
+ }
/* A member cannot be in type void */
if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
btf_verifier_log_member(env, t, member,
@@ -1755,6 +1797,13 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* enum type either no name or a valid one */
+ if (t->name_off &&
+ !btf_name_valid_identifier(env->btf, t->name_off)) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+
btf_verifier_log_type(env, t, NULL);

for (i = 0; i < nr_enums; i++) {
@@ -1764,6 +1813,14 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}

+ /* enum member must have a valid name */
+ if (!enums[i].name_off ||
+ !btf_name_valid_identifier(btf, enums[i].name_off)) {
+ btf_verifier_log_type(env, t, "Invalid name");
+ return -EINVAL;
+ }
+
+
btf_verifier_log(env, "\t%s val=%d\n",
btf_name_by_offset(btf, enums[i].name_off),
enums[i].val);
--
2.20.1