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From: Yonghong Song <yhs@fb.com>
To: Alexei Starovoitov <ast@fb.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next v2 04/11] bpf: add bpf_for_each_map_elem() helper
Date: Tue, 23 Feb 2021 11:37:40 -0800	[thread overview]
Message-ID: <b45301e2-3c22-f12a-9e91-538363528389@fb.com> (raw)
In-Reply-To: <c837ae55-2487-2f39-47f6-a18781dc6fcc@fb.com>



On 2/23/21 10:46 AM, Alexei Starovoitov wrote:
> On 2/23/21 10:39 AM, Yonghong Song wrote:
>>
>>
>> On 2/22/21 12:59 PM, Alexei Starovoitov wrote:
>>> On Wed, Feb 17, 2021 at 10:18:07AM -0800, Yonghong Song wrote:
>>>> @@ -5893,6 +6004,14 @@ static int retrieve_ptr_limit(const struct 
>>>> bpf_reg_state *ptr_reg,
>>>>           else
>>>>               *ptr_limit = -off;
>>>>           return 0;
>>>> +    case PTR_TO_MAP_KEY:
>>>> +        if (mask_to_left) {
>>>> +            *ptr_limit = ptr_reg->umax_value + ptr_reg->off;
>>>> +        } else {
>>>> +            off = ptr_reg->smin_value + ptr_reg->off;
>>>> +            *ptr_limit = ptr_reg->map_ptr->key_size - off;
>>>> +        }
>>>> +        return 0;
>>>
>>> This part cannot be exercised because for_each will require cap_bpf.
>>> Eventually we might relax this requirement and above code will be 
>>> necessary.
>>> Could you manually test it that it's working as expected by forcing
>>> sanitize_ptr_alu() to act on it?
>>
>> I did some manual test and hacking the verifier to make this code 
>> executed and it looks fine and verifier succeeded.
>>
>> But since this code won't execute with current implementation
>> with bpf_capable(). It probably makes sense to remove this code
>> for now and will add it back later once bpf_pseudo_func is permitted for
>> unprivileged user.
> 
> I think we might forget it later.
> I would leave the code here and maybe add the comment that it's tested
> for future use, but not needed yet.

okay. will keep it.


  reply	other threads:[~2021-02-23 19:38 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-17 18:18 [PATCH bpf-next v2 00/11] bpf: add bpf_for_each_map_elem() helper Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 01/11] bpf: factor out visit_func_call_insn() in check_cfg() Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 02/11] bpf: factor out verbose_invalid_scalar() Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 03/11] bpf: refactor check_func_call() to allow callback function Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 04/11] bpf: add bpf_for_each_map_elem() helper Yonghong Song
2021-02-22 20:59   ` Alexei Starovoitov
2021-02-23 18:39     ` Yonghong Song
2021-02-23 18:46       ` Alexei Starovoitov
2021-02-23 19:37         ` Yonghong Song [this message]
2021-02-17 18:18 ` [PATCH bpf-next v2 05/11] bpf: add hashtab support for " Yonghong Song
2021-02-22 22:56   ` Alexei Starovoitov
2021-02-23 18:41     ` Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 06/11] bpf: add arraymap " Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 07/11] libbpf: move function is_ldimm64() earlier in libbpf.c Yonghong Song
2021-02-23  8:06   ` Andrii Nakryiko
2021-02-17 18:18 ` [PATCH bpf-next v2 08/11] libbpf: support local function pointer relocation Yonghong Song
2021-02-23  8:03   ` Andrii Nakryiko
2021-02-23 18:55     ` Yonghong Song
2021-02-23 19:07       ` Alexei Starovoitov
2021-02-23 19:21         ` Andrii Nakryiko
2021-02-23 19:19       ` Andrii Nakryiko
2021-02-23 19:47         ` Yonghong Song
2021-02-23 21:24           ` Andrii Nakryiko
2021-02-17 18:18 ` [PATCH bpf-next v2 09/11] bpftool: print local function pointer properly Yonghong Song
2021-02-23  8:06   ` Andrii Nakryiko
2021-02-23 19:00     ` Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 10/11] selftests/bpf: add hashmap test for bpf_for_each_map_elem() helper Yonghong Song
2021-02-17 18:18 ` [PATCH bpf-next v2 11/11] selftests/bpf: add arraymap " Yonghong Song
2021-02-17 18:29 ` [PATCH bpf-next v2 00/11] bpf: add " Yonghong Song

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