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.
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.
>
> > + if (strncmp(nametag, prog_name, sizeof(prog_name))) {
> > + close(fd);
> > + continue;
> > + }
> > + }
> > +
> > if (nb_fds > 0) {
> > tmp = realloc(*fds, (nb_fds + 1) * sizeof(int));
> > if (!tmp) {
> > @@ -820,7 +829,7 @@ int prog_parse_fds(int *argc, char ***argv, int **fds)
> > NEXT_ARGP();
> >
> > name = **argv;
> > - if (strlen(name) > BPF_OBJ_NAME_LEN - 1) {
> > + if (strlen(name) > MAX_PROG_FULL_NAME - 1) {
> > p_err("can't parse name");
> > return -1;
> > }
>
> Looks good, thank you!
>
> Reviewed-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
