From: Jiri Olsa <jolsa@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>, 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 08/11] bpf: Add BTF whitelist support
Date: Fri, 19 Jun 2020 15:29:29 +0200 [thread overview]
Message-ID: <20200619132929.GI2465907@krava> (raw)
In-Reply-To: <CAEf4Bzaj-t0UYLiJh9czenqVtsi5UuviX_AqgpEq=gJx6WCHrw@mail.gmail.com>
On Thu, Jun 18, 2020 at 09:29:58PM -0700, Andrii Nakryiko wrote:
SNIP
> > @@ -4669,3 +4670,15 @@ u32 btf_id(const struct btf *btf)
> > {
> > return btf->id;
> > }
> > +
> > +static int btf_id_cmp_func(const void *a, const void *b)
> > +{
> > + const int *pa = a, *pb = b;
> > +
> > + return *pa - *pb;
> > +}
> > +
> > +bool btf_whitelist_search(int id, int list[], int cnt)
>
> whitelist is a bit too specific, this functionality can be used for
> blacklisting as well, no?
>
> How about instead of "open coding" separately int list[] + int cnt, we
> define a struct:
>
> struct btf_id_set {
> u32 cnt;
> u32 ids[];
> };
>
> and pass that around?
>
> This function then can be generic
>
> bool btf_id_set_contains(struct btf_id_set *set, u32 id);
>
> Then it's usable for both whitelist and blacklist? _contains also
> clearly implies what's the return result, while _search isn't so clear
> in that regard.
yep, looks better this way, will change
>
>
> > +{
> > + return bsearch(&id, list, cnt, sizeof(int), btf_id_cmp_func) != NULL;
> > +}
> > diff --git a/kernel/bpf/btf_ids.h b/kernel/bpf/btf_ids.h
> > index 68aa5c38a37f..a90c09faa515 100644
> > --- a/kernel/bpf/btf_ids.h
> > +++ b/kernel/bpf/btf_ids.h
> > @@ -67,4 +67,42 @@ asm( \
> > #name ":; \n" \
> > ".popsection; \n");
> >
> > +
> > +/*
> > + * The BTF_WHITELIST_ENTRY/END macros pair defines sorted
> > + * list of BTF IDs plus its members count, with following
> > + * layout:
> > + *
> > + * BTF_WHITELIST_ENTRY(list2)
> > + * BTF_ID(type1, name1)
> > + * BTF_ID(type2, name2)
> > + * BTF_WHITELIST_END(list)
>
> It kind of sucks you need two separate ENTRY/END macro (btw, START/END
> or BEGIN/END would be a bit more "paired"), and your example clearly
ok, START/END it is
> shows why: it is not self-consistent (list2 on start, list on end ;).
ugh ;-)
> But doing variadic macro like this would be a nightmare as well,
> unfortunately. :(
>
> > + *
> > + * __BTF_ID__sort__list:
> > + * list2_cnt:
> > + * .zero 4
> > + * list2:
> > + * __BTF_ID__type1__name1__3:
> > + * .zero 4
> > + * __BTF_ID__type2__name2__4:
> > + * .zero 4
> > + *
> > + */
> > +#define BTF_WHITELIST_ENTRY(name) \
> > +asm( \
> > +".pushsection " SECTION ",\"a\"; \n" \
> > +".global __BTF_ID__sort__" #name "; \n" \
> > +"__BTF_ID__sort__" #name ":; \n" \
>
> I mentioned in the previous patch already, I think "sort" is a bad
> name, consider "set" (or "list", but you used list name already for a
> slightly different macro).
yes, I replied to this in another email
>
> > +".global " #name "_cnt; \n" \
> > +#name "_cnt:; \n" \
>
> This label/symbol isn't necessary, why polluting the symbol table?
XXX_cnt variable is used in search function, but isn't needed
if we use that 'struct btf_id_set' you proposed
>
> > +".zero 4 \n" \
> > +".popsection; \n"); \
> > +BTF_ID_LIST(name)
> > +
> > +#define BTF_WHITELIST_END(name) \
> > +asm( \
> > +".pushsection " SECTION ",\"a\"; \n" \
> > +".size __BTF_ID__sort__" #name ", .-" #name " \n" \
> > +".popsection; \n");
> > +
> > #endif
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index bee3da2cd945..5a9a6fd72907 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -4633,6 +4633,11 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn
> > return -EINVAL;
> > }
> >
> > + if (fn->allowed && !fn->allowed(env->prog)) {
> > + verbose(env, "helper call is not allowed in probe\n");
>
> nit: probe -> program, or just drop "in probe" part altogether
ok
thnaks,
jirka
next prev parent reply other threads:[~2020-06-19 13:29 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 10:05 [PATCHv3 0/9] bpf: Add d_path helper Jiri Olsa
2020-06-16 10:05 ` [PATCH 01/11] bpf: Add btfid tool to resolve BTF IDs in ELF object Jiri Olsa
2020-06-19 0:38 ` Andrii Nakryiko
2020-06-19 13:03 ` Jiri Olsa
2020-06-19 18:12 ` Andrii Nakryiko
2020-06-22 8:59 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 02/11] bpf: Compile btfid tool at kernel compilation start Jiri Olsa
2020-06-18 20:40 ` John Fastabend
2020-06-18 21:17 ` John Fastabend
2020-06-19 13:23 ` Jiri Olsa
2020-06-19 0:40 ` Andrii Nakryiko
2020-06-19 0:47 ` Arnaldo Carvalho de Melo
2020-06-19 2:08 ` Alexei Starovoitov
2020-06-19 3:51 ` Andrii Nakryiko
2020-06-16 10:05 ` [PATCH 03/11] bpf: Add btf_ids object Jiri Olsa
2020-06-19 0:56 ` Andrii Nakryiko
2020-06-19 1:06 ` Andrii Nakryiko
2020-06-19 13:16 ` Jiri Olsa
2020-06-19 13:13 ` Jiri Olsa
2020-06-19 18:15 ` Andrii Nakryiko
2020-06-19 1:02 ` Andrii Nakryiko
2020-06-19 13:05 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 04/11] bpf: Resolve BTF IDs in vmlinux image Jiri Olsa
2020-06-16 10:05 ` [PATCH 05/11] bpf: Remove btf_id helpers resolving Jiri Olsa
2020-06-19 1:10 ` Andrii Nakryiko
2020-06-19 13:18 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 06/11] bpf: Do not pass enum bpf_access_type to btf_struct_access Jiri Olsa
2020-06-19 3:58 ` Andrii Nakryiko
2020-06-19 13:23 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 07/11] bpf: Allow nested BTF object to be refferenced by BTF object + offset Jiri Olsa
2020-06-16 10:05 ` [PATCH 08/11] bpf: Add BTF whitelist support Jiri Olsa
2020-06-19 4:29 ` Andrii Nakryiko
2020-06-19 13:29 ` Jiri Olsa [this message]
2020-06-16 10:05 ` [PATCH 09/11] bpf: Add d_path helper Jiri Olsa
2020-06-19 4:35 ` Andrii Nakryiko
2020-06-19 13:31 ` Jiri Olsa
2020-06-19 18:25 ` Andrii Nakryiko
2020-06-22 9:02 ` Jiri Olsa
2020-06-22 19:18 ` Andrii Nakryiko
2020-06-23 10:02 ` Jiri Olsa
2020-06-23 18:58 ` Andrii Nakryiko
2020-06-23 20:14 ` Jiri Olsa
2020-06-23 20:17 ` Andrii Nakryiko
2020-06-16 10:05 ` [PATCH 10/11] selftests/bpf: Add verifier test for " Jiri Olsa
2020-06-19 4:38 ` Andrii Nakryiko
2020-06-19 13:32 ` Jiri Olsa
2020-06-16 10:05 ` [PATCH 11/11] selftests/bpf: Add " Jiri Olsa
2020-06-19 4:44 ` Andrii Nakryiko
2020-06-19 13:34 ` Jiri Olsa
2020-06-18 20:57 ` [PATCHv3 0/9] bpf: Add " John Fastabend
2020-06-19 12:35 ` Jiri Olsa
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