netdev - [PATCH bpf-next 1/3] bpf: btf: check name validity for various types

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Date:   Mon, 26 Nov 2018 21:17:13 -0800
From:   Yonghong Song <yhs@...com>
To:     <ast@...com>, <daniel@...earbox.net>, <netdev@...r.kernel.org>,
        <kafai@...com>
CC:     <kernel-team@...com>
Subject: [PATCH bpf-next 1/3] bpf: btf: check name validity for various types

Commit 2667a2626f4d ("bpf: btf: Add BTF_KIND_FUNC
and BTF_KIND_FUNC_PROTO") checked the name validity
for BTF_KIND_FUNC/BTF_KIND_FUNC_PROTO types such that:
 . BTF_KIND_FUNC must have a valid identifier name
 . BTF_KIND_PROTO must have a null name
 . The argument name of BTF_KIND_FUNC/BTF_KIND_FUNC_PROTO,
   if not null, must be a valid identifier.

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.

Acked-by: Martin KaFai Lau <kafai@...com>
Signed-off-by: Yonghong Song <yhs@...com>
---
 kernel/bpf/btf.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index a09b2f94ab25..793acba40b4c 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -1195,6 +1195,22 @@ 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;
@@ -1353,6 +1369,13 @@ 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;
@@ -1409,6 +1432,12 @@ 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;
@@ -1585,6 +1614,13 @@ 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;
@@ -1596,6 +1632,12 @@ 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,
@@ -1783,6 +1825,13 @@ 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++) {
@@ -1792,6 +1841,14 @@ 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);
-- 
2.17.1