On 01/08/2022 13:39, Manu Bretelle wrote:
> On Mon, Aug 1, 2022 at 5:18 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>>
>> On 31/07/2022 19:10, Manu Bretelle wrote:
>>> bpftool was limiting the length of names to BPF_OBJ_NAME_LEN in prog_parse
>>> fds.
>>>
>>> Since commit b662000aff84 ("bpftool: Adding support for BTF program names")
>>> we can get the full program name from BTF.
>>>
>>> This patch removes the restriction of name length when running `bpftool
>>> prog show name ${name}`.
>>>
>>> Test:
>>> Tested against some internal program names that were longer than
>>> `BPF_OBJ_NAME_LEN`, here a redacted example of what was ran to test.
>>>
>>> # previous behaviour
>>> $ sudo bpftool prog show name some_long_program_name
>>> Error: can't parse name
>>> # with the patch
>>> $ sudo ./bpftool prog show name some_long_program_name
>>> 123456789: tracing name some_long_program_name tag taghexa gpl ....
>>> ...
>>> ...
>>> ...
>>> # too long
>>> sudo ./bpftool prog show name $(python3 -c 'print("A"*128)')
>>> Error: can't parse name
>>> # not too long but no match
>>> $ sudo ./bpftool prog show name $(python3 -c 'print("A"*127)')
>>>
>>> Signed-off-by: Manu Bretelle <chantr4@xxxxxxxxx>
>>>
>>> ---
>>>
>>> v1 -> v2:
>>> * Fix commit message to follow patch submission guidelines
>>> * use strncmp instead of strcmp
>>> * reintroduce arg length check against MAX_PROG_FULL_NAME
>>>
>>>
>>> tools/bpf/bpftool/common.c | 15 ++++++++++++---
>>> 1 file changed, 12 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
>>> index 067e9ea59e3b..3ea747b3b194 100644
>>> --- a/tools/bpf/bpftool/common.c
>>> +++ b/tools/bpf/bpftool/common.c
>>> @@ -722,6 +722,7 @@ print_all_levels(__maybe_unused enum libbpf_print_level level,
>>>
>>> static int prog_fd_by_nametag(void *nametag, int **fds, bool tag)
>>> {
>>> + char prog_name[MAX_PROG_FULL_NAME];
>>> unsigned int id = 0;
>>> int fd, nb_fds = 0;
>>> void *tmp;
>>> @@ -754,12 +755,20 @@ static int prog_fd_by_nametag(void *nametag, int **fds, bool tag)
>>> goto err_close_fd;
>>> }
>>>
>>> - if ((tag && memcmp(nametag, info.tag, BPF_TAG_SIZE)) ||
>>> - (!tag && strncmp(nametag, info.name, BPF_OBJ_NAME_LEN))) {
>>> + if (tag && memcmp(nametag, info.tag, BPF_TAG_SIZE)) {
>>> close(fd);
>>> continue;
>>> }
>>>
>>> + if (!tag) {
>>> + get_prog_full_name(&info, fd, prog_name,
>>> + sizeof(prog_name));
>>
>> Nit: This line should be aligned with the opening parenthesis from the
>> line above, checkpatch.pl complains about it. Probably not worth sending
>> a new version just for that, though.
>
> Yeah, I saw that on patchwork. For some reason, the `checkpatch.pl`
> version I had from bpf-next tree did not catch this.
It's because it's a low-level issue: a “check” for checkpatch, not a
“warning” or an “error”. Checkpatch will only report this if you run it
with "--strict", which the CI does.
> Originally, I was getting an error because it was more than 75 char
> long. Eventually found out that shiftwidth should have been set to 8
> (mine was 4).
> I am happy to provide a corrected version if you want, this is really
> just a matter of a minute now that I have the right vim indentation
> setting.
OK let's do this. Please keep my Reviewed-by on v3.
