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Date: Tue, 11 Feb 2025 10:48:52 +0000
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Subject: Re: [PATCH bpf-next v2] bpftool: Check map name length when map
 create
To: Rong Tao <rtoax@foxmail.com>, ast@kernel.org, daniel@iogearbox.net
Cc: rongtao@cestc.cn, Andrii Nakryiko <andrii@kernel.org>,
 Martin KaFai Lau <martin.lau@linux.dev>, Eduard Zingerman
 <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
 Yonghong Song <yonghong.song@linux.dev>,
 John Fastabend <john.fastabend@gmail.com>, KP Singh <kpsingh@kernel.org>,
 Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
 Jiri Olsa <jolsa@kernel.org>,
 "open list:BPF [TOOLING] (bpftool)" <bpf@vger.kernel.org>,
 open list <linux-kernel@vger.kernel.org>
References: <tencent_26592A2BAF08A3A688A50600421559929708@qq.com>
From: Quentin Monnet <qmo@kernel.org>
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In-Reply-To: <tencent_26592A2BAF08A3A688A50600421559929708@qq.com>
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2025-02-11 18:38 UTC+0800 ~ Rong Tao <rtoax@foxmail.com>
> From: Rong Tao <rongtao@cestc.cn>
> 
> The size of struct bpf_map::name is BPF_OBJ_NAME_LEN (16).
> 
> bpf(2) {
>   map_create() {
>     bpf_obj_name_cpy(map->name, attr->map_name, sizeof(attr->map_name));
>   }
> }
> 
> When specifying a map name using bpftool map create name, no error is
> reported if the name length is greater than 15.
> 
>     $ sudo bpftool map create /sys/fs/bpf/12345678901234567890 \
>         type array key 4 value 4 entries 5 name 12345678901234567890
> 
> Users will think that 12345678901234567890 is legal, but this name cannot
> be used to index a map.
> 
>     $ sudo bpftool map show name 12345678901234567890
>     Error: can't parse name
> 
>     $ sudo bpftool map show
>     ...
>     1249: array  name 123456789012345  flags 0x0
>     	key 4B  value 4B  max_entries 5  memlock 304B
> 
>     $ sudo bpftool map show name 123456789012345
>     1249: array  name 123456789012345  flags 0x0
>     	key 4B  value 4B  max_entries 5  memlock 304B
> 
> The map name provided in the command line is truncated, but no error is
> reported. This submission checks the length of the map name.
> 
> Signed-off-by: Rong Tao <rongtao@cestc.cn>


Reviewed-by: Quentin Monnet <qmo@kernel.org>

Thank you!