> From: Stanislav Fomichev [mailto:sdf@xxxxxxxxxx] > Sent: Thursday, July 21, 2022 12:48 AM > On Wed, Jul 20, 2022 at 3:44 PM Roberto Sassu <roberto.sassu@xxxxxxxxxx> > wrote: > > > > > From: Stanislav Fomichev [mailto:sdf@xxxxxxxxxx] > > > Sent: Thursday, July 21, 2022 12:38 AM > > > On Wed, Jul 20, 2022 at 3:30 PM Roberto Sassu > <roberto.sassu@xxxxxxxxxx> > > > wrote: > > > > > > > > > From: Stanislav Fomichev [mailto:sdf@xxxxxxxxxx] > > > > > Sent: Wednesday, July 20, 2022 5:57 PM > > > > > On Wed, Jul 20, 2022 at 1:02 AM Roberto Sassu > > > <roberto.sassu@xxxxxxxxxx> > > > > > wrote: > > > > > > > > > > > > > From: Stanislav Fomichev [mailto:sdf@xxxxxxxxxx] > > > > > > > Sent: Tuesday, July 19, 2022 10:40 PM > > > > > > > On Tue, Jul 19, 2022 at 12:40 PM Joe Burton > > > <jevburton.kernel@xxxxxxxxx> > > > > > > > wrote: > > > > > > > > > > > > > > > > From: Joe Burton <jevburton@xxxxxxxxxx> > > > > > > > > > > > > > > > > Add an extensible variant of bpf_obj_get() capable of setting the > > > > > > > > `file_flags` parameter. > > > > > > > > > > > > > > > > This parameter is needed to enable unprivileged access to BPF > maps. > > > > > > > > Without a method like this, users must manually make the syscall. > > > > > > > > > > > > > > > > Signed-off-by: Joe Burton <jevburton@xxxxxxxxxx> > > > > > > > > > > > > > > Reviewed-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > > > > > > > > > > > > > > For context: > > > > > > > We've found this out while we were trying to add support for unpriv > > > > > > > processes to open pinned r-x maps. > > > > > > > Maybe this deserves a test as well? Not sure. > > > > > > > > > > > > Hi Stanislav, Joe > > > > > > > > > > > > I noticed now this patch. I'm doing a broader work to add opts > > > > > > to bpf_*_get_fd_by_id(). I also adjusted permissions of bpftool > > > > > > depending on the operation type (e.g. show, dump: BPF_F_RDONLY). > > > > > > > > > > > > Will send it soon (I'm trying to solve an issue with the CI, where > > > > > > libbfd is not available in the VM doing actual tests). > > > > > > > > > > Is something like this patch included in your series as well? Can you > > > > > use this new interface or do you need something different? > > > > > > > > It is very similar. Except that I called it bpf_get_fd_opts, as it > > > > is shared with the bpf_*_get_fd_by_id() functions. The member > > > > name is just flags, plus an extra u32 for alignment. > > > > > > We can bikeshed the naming, but we've been using existing conventions > > > where opts fields match syscall fields, that seems like a sensible > > > thing to do? > > > > The only problem is that bpf_*_get_fd_by_id() functions would > > set the open_flags member of bpf_attr. > > > > Flags would be good for both, even if not exact. Believe me, > > duplicating the opts would just create more confusion. > > Wait, that's completely different, right? We are talking here about > BPF_OBJ_GET (which has related BPF_OBJ_PIN). > Your GET_XXX_BY_ID are different so you'll still have to have another > wrapper with opts? Yes, they have different wrappers, just accept the same opts as obj_get(). From bpftool subcommands you want to set the correct permission, and propagate it uniformly to bpf_*_get_fd_by_id() or obj_get(). See map_parse_fds(). Roberto > > > > It needs to be shared, as there are functions in bpftool calling > > > > both. Since the meaning of flags is the same, seems ok sharing. > > > > > > So I guess there are no objections to the current patch? If it gets > > > accepted, you should be able to drop some of your code and use this > > > new bpf_obj_get_opts.. > > > > If you use a name good also for bpf_*_get_fd_by_id() and flags > > as structure member name, that would be ok. > > > > Roberto > > > > > > Roberto > > > > > > > > > > Roberto > > > > > > > > > > > > > > --- > > > > > > > > tools/lib/bpf/bpf.c | 10 ++++++++++ > > > > > > > > tools/lib/bpf/bpf.h | 9 +++++++++ > > > > > > > > tools/lib/bpf/libbpf.map | 1 + > > > > > > > > 3 files changed, 20 insertions(+) > > > > > > > > > > > > > > > > diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c > > > > > > > > index 5eb0df90eb2b..5acb0e8bd13c 100644 > > > > > > > > --- a/tools/lib/bpf/bpf.c > > > > > > > > +++ b/tools/lib/bpf/bpf.c > > > > > > > > @@ -578,12 +578,22 @@ int bpf_obj_pin(int fd, const char > > > *pathname) > > > > > > > > } > > > > > > > > > > > > > > > > int bpf_obj_get(const char *pathname) > > > > > > > > +{ > > > > > > > > + LIBBPF_OPTS(bpf_obj_get_opts, opts); > > > > > > > > + return bpf_obj_get_opts(pathname, &opts); > > > > > > > > +} > > > > > > > > + > > > > > > > > +int bpf_obj_get_opts(const char *pathname, const struct > > > > > bpf_obj_get_opts > > > > > > > *opts) > > > > > > > > { > > > > > > > > union bpf_attr attr; > > > > > > > > int fd; > > > > > > > > > > > > > > > > + if (!OPTS_VALID(opts, bpf_obj_get_opts)) > > > > > > > > + return libbpf_err(-EINVAL); > > > > > > > > + > > > > > > > > memset(&attr, 0, sizeof(attr)); > > > > > > > > attr.pathname = ptr_to_u64((void *)pathname); > > > > > > > > + attr.file_flags = OPTS_GET(opts, file_flags, 0); > > > > > > > > > > > > > > > > fd = sys_bpf_fd(BPF_OBJ_GET, &attr, sizeof(attr)); > > > > > > > > return libbpf_err_errno(fd); > > > > > > > > diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h > > > > > > > > index 88a7cc4bd76f..f31b493b5f9a 100644 > > > > > > > > --- a/tools/lib/bpf/bpf.h > > > > > > > > +++ b/tools/lib/bpf/bpf.h > > > > > > > > @@ -270,8 +270,17 @@ LIBBPF_API int bpf_map_update_batch(int > fd, > > > > > const > > > > > > > void *keys, const void *values > > > > > > > > __u32 *count, > > > > > > > > const struct bpf_map_batch_opts *opts); > > > > > > > > > > > > > > > > +struct bpf_obj_get_opts { > > > > > > > > + size_t sz; /* size of this struct for forward/backward > compatibility > > > */ > > > > > > > > + > > > > > > > > + __u32 file_flags; > > > > > > > > +}; > > > > > > > > +#define bpf_obj_get_opts__last_field file_flags > > > > > > > > + > > > > > > > > LIBBPF_API int bpf_obj_pin(int fd, const char *pathname); > > > > > > > > LIBBPF_API int bpf_obj_get(const char *pathname); > > > > > > > > +LIBBPF_API int bpf_obj_get_opts(const char *pathname, > > > > > > > > + const struct bpf_obj_get_opts *opts); > > > > > > > > > > > > > > > > struct bpf_prog_attach_opts { > > > > > > > > size_t sz; /* size of this struct for forward/backward > compatibility > > > */ > > > > > > > > diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map > > > > > > > > index 0625adb9e888..119e6e1ea7f1 100644 > > > > > > > > --- a/tools/lib/bpf/libbpf.map > > > > > > > > +++ b/tools/lib/bpf/libbpf.map > > > > > > > > @@ -355,6 +355,7 @@ LIBBPF_0.8.0 { > > > > > > > > > > > > > > > > LIBBPF_1.0.0 { > > > > > > > > global: > > > > > > > > + bpf_obj_get_opts; > > > > > > > > bpf_prog_query_opts; > > > > > > > > bpf_program__attach_ksyscall; > > > > > > > > btf__add_enum64; > > > > > > > > -- > > > > > > > > 2.37.0.170.g444d1eabd0-goog > > > > > > > >
