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

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Message-ID: <f4d45ea4-2c8d-1f71-786a-e53aa412818b@fb.com>
Date:   Tue, 27 Nov 2018 19:57:00 +0000
From:   Yonghong Song <yhs@...com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
CC:     Alexei Starovoitov <ast@...com>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Martin Lau <kafai@...com>, Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH bpf-next 1/3] bpf: btf: check name validity for various
 types



On 11/27/18 11:02 AM, Alexei Starovoitov wrote:
> On Mon, Nov 26, 2018 at 09:17:13PM -0800, Yonghong Song wrote:
>> 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>
> ...
>>   	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)) {
> 
> Looks like some of these changes need to go into bpf tree.
> please split it up and let's try to minimize the conflicts between bpf and bpf-next

Make sense. Will restructure and resubmit for bpf in the next version.

> Thanks!
>