From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
Martin KaFai Lau <kafai@fb.com>, David Miller <davem@redhat.com>,
John Fastabend <john.fastabend@gmail.com>,
Wenbo Zhang <ethercflow@gmail.com>,
KP Singh <kpsingh@chromium.org>, Andrii Nakryiko <andriin@fb.com>,
Brendan Gregg <bgregg@netflix.com>,
Florent Revest <revest@chromium.org>,
Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v4 bpf-next 07/14] bpf: Allow nested BTF object to be refferenced by BTF object + offset
Date: Tue, 30 Jun 2020 13:07:17 -0700 [thread overview]
Message-ID: <CAEf4BzYh7s8=F4FeXQfxUFQiSN-KSDw1N3k7fMWA0AeLSPu-GQ@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzZA3QqA=f_E8CUASVajxEsThq+Ww2Ax6az82wibx1dgOg@mail.gmail.com>
On Tue, Jun 30, 2020 at 1:05 PM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Thu, Jun 25, 2020 at 4:49 PM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Adding btf_struct_address function that takes 2 BTF objects
> > and offset as arguments and checks whether object A is nested
> > in object B on given offset.
> >
> > This function will be used when checking the helper function
> > PTR_TO_BTF_ID arguments. If the argument has an offset value,
> > the btf_struct_address will check if the final address is
> > the expected BTF ID.
> >
> > This way we can access nested BTF objects under PTR_TO_BTF_ID
> > pointer type and pass them to helpers, while they still point
> > to valid kernel BTF objects.
> >
> > Using btf_struct_access to implement new btf_struct_address
> > function, because it already walks down the given BTF object.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > include/linux/bpf.h | 3 ++
> > kernel/bpf/btf.c | 67 ++++++++++++++++++++++++++++++++++++++-----
> > kernel/bpf/verifier.c | 37 +++++++++++++++---------
> > 3 files changed, 87 insertions(+), 20 deletions(-)
> >
[...]
> >
> > error:
> > bpf_log(log, "access beyond struct %s at off %u size %u\n",
> > @@ -4043,9 +4054,21 @@ int btf_struct_access(struct bpf_verifier_log *log,
> >
> > /* adjust offset we're looking for */
> > off -= moff;
> > +
> > + /* We are nexting into another struct,
> > + * check if we are crossing expected ID.
> > + */
> > + if (data->op == ACCESS_EXPECT && !off && t == data->exp_type)
>
> before you can do this type check, you need to btf_type_skip_modifiers() first.
>
Ignore this part, btf_resolve_size() (somewhat unexpectedly) already does that.
> > + return 0;
> > goto again;
> > }
> >
> > + /* We are interested only in structs for expected ID,
> > + * bail out.
> > + */
> > + if (data->op == ACCESS_EXPECT)
> > + return -EINVAL;
> > +
> > if (btf_type_is_ptr(mtype)) {
> > const struct btf_type *stype;
> > u32 id;
[...]
next prev parent reply other threads:[~2020-06-30 20:07 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 22:12 [PATCH v4 bpf-next 00/14] bpf: Add d_path helper Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 01/14] bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object Jiri Olsa
2020-06-26 20:53 ` Andrii Nakryiko
2020-06-26 21:09 ` Yonghong Song
2020-06-28 19:09 ` Alexei Starovoitov
2020-06-28 19:35 ` Jiri Olsa
2020-06-28 20:53 ` Yonghong Song
2020-06-25 22:12 ` [PATCH v4 bpf-next 02/14] bpf: Compile resolve_btfids tool at kernel compilation start Jiri Olsa
2020-06-26 21:28 ` Andrii Nakryiko
2020-06-28 19:48 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 03/14] bpf: Add BTF_ID_LIST/BTF_ID macros Jiri Olsa
2020-06-26 21:32 ` Andrii Nakryiko
2020-06-28 19:50 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 04/14] bpf: Resolve BTF IDs in vmlinux image Jiri Olsa
2020-06-26 21:34 ` Andrii Nakryiko
2020-06-25 22:12 ` [PATCH v4 bpf-next 05/14] bpf: Remove btf_id helpers resolving Jiri Olsa
2020-06-26 21:36 ` Yonghong Song
2020-06-26 21:40 ` Andrii Nakryiko
2020-06-26 23:29 ` Yonghong Song
2020-06-28 18:50 ` Alexei Starovoitov
2020-06-28 20:00 ` Andrii Nakryiko
2020-06-28 20:16 ` Jiri Olsa
2020-06-28 20:59 ` Yonghong Song
2020-06-28 21:20 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 06/14] bpf: Use BTF_ID to resolve bpf_ctx_convert struct Jiri Olsa
2020-06-26 21:44 ` Andrii Nakryiko
2020-06-26 21:44 ` Yonghong Song
2020-06-28 19:52 ` Jiri Olsa
2020-06-25 22:12 ` [PATCH v4 bpf-next 07/14] bpf: Allow nested BTF object to be refferenced by BTF object + offset Jiri Olsa
2020-06-30 1:52 ` Andrii Nakryiko
2020-06-30 13:54 ` Jiri Olsa
2020-06-30 20:05 ` Andrii Nakryiko
2020-06-30 20:07 ` Andrii Nakryiko [this message]
2020-07-02 10:08 ` Jiri Olsa
2020-07-06 23:15 ` Andrii Nakryiko
2020-06-25 22:12 ` [PATCH v4 bpf-next 08/14] bpf: Add BTF_SET_START/END macros Jiri Olsa
2020-06-26 21:49 ` Andrii Nakryiko
2020-06-25 22:12 ` [PATCH v4 bpf-next 09/14] bpf: Add info about .BTF.ids section to btf.rst Jiri Olsa
2020-06-25 22:13 ` [PATCH v4 bpf-next 10/14] bpf: Add d_path helper Jiri Olsa
2020-06-26 20:38 ` Andrii Nakryiko
2020-06-28 19:42 ` Jiri Olsa
2020-07-16 23:13 ` KP Singh
2020-07-17 8:28 ` Jiri Olsa
2020-06-25 22:13 ` [PATCH v4 bpf-next 11/14] tools headers: Adopt verbatim copy of btf_ids.h from kernel sources Jiri Olsa
2020-06-26 21:51 ` Andrii Nakryiko
2020-06-25 22:13 ` [PATCH v4 bpf-next 12/14] selftests/bpf: Add verifier test for d_path helper Jiri Olsa
2020-06-30 1:30 ` Andrii Nakryiko
2020-06-25 22:13 ` [PATCH v4 bpf-next 13/14] selftests/bpf: Add " Jiri Olsa
2020-06-26 21:55 ` Andrii Nakryiko
2020-06-28 19:55 ` Jiri Olsa
2020-06-25 22:13 ` [PATCH v4 bpf-next 14/14] selftests/bpf: Add test for resolve_btfids Jiri Olsa
2020-06-30 1:43 ` Andrii Nakryiko
2020-06-30 14:27 ` Jiri Olsa
2020-06-30 18:13 ` Andrii Nakryiko
2020-06-30 1:54 ` [PATCH v4 bpf-next 00/14] bpf: Add d_path helper Andrii Nakryiko
2020-06-30 13:55 ` Jiri Olsa
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