From: Florent Revest <revest@chromium.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Brendan Jackman <jackmanb@chromium.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v3 6/6] selftests/bpf: Add a series of tests for bpf_snprintf
Date: Wed, 14 Apr 2021 11:21:22 +0200 [thread overview]
Message-ID: <CABRcYm+v7xC8WsxYu6BoiEX1vhQSVSX5U-LyUnevGt1tFud5tA@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzZ6cLio0ZZEkc5iYp9yWg3Fc1ZORBTr85TdoqF-sRU3DQ@mail.gmail.com>
On Wed, Apr 14, 2021 at 1:21 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Mon, Apr 12, 2021 at 8:38 AM Florent Revest <revest@chromium.org> wrote:
> >
> > This exercises most of the format specifiers.
> >
> > Signed-off-by: Florent Revest <revest@chromium.org>
> > Acked-by: Andrii Nakryiko <andrii@kernel.org>
> > ---
>
> As I mentioned on another patch, we probably need negative tests even
> more than positive ones.
Agreed.
> I think an easy and nice way to do this is to have a separate BPF
> skeleton where fmt string and arguments are provided through read-only
> global variables, so that user-space can re-use the same BPF skeleton
> to simulate multiple cases. BPF program itself would just call
> bpf_snprintf() and store the returned result.
Ah, great idea! I was thinking of having one skeleton for each but it
would be a bit much indeed.
Because the format string needs to be in a read only map though, I
hope it can be modified from userspace before loading. I'll try it out
and see :) if it doesn't work I'll just use more skeletons
> Whether we need to validate the verifier log is up to debate (though
> it's not that hard to do by overriding libbpf_print_fn() callback),
> I'd be ok at least knowing that some bad format strings are rejected
> and don't crash the kernel.
Alright :)
>
> > .../selftests/bpf/prog_tests/snprintf.c | 81 +++++++++++++++++++
> > .../selftests/bpf/progs/test_snprintf.c | 74 +++++++++++++++++
> > 2 files changed, 155 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/snprintf.c
> > create mode 100644 tools/testing/selftests/bpf/progs/test_snprintf.c
> >
>
> [...]
next prev parent reply other threads:[~2021-04-14 9:21 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 15:37 [PATCH bpf-next v3 0/6] Add a snprintf eBPF helper Florent Revest
2021-04-12 15:37 ` [PATCH bpf-next v3 1/6] bpf: Factorize bpf_trace_printk and bpf_seq_printf Florent Revest
2021-04-13 23:01 ` Andrii Nakryiko
2021-04-14 9:56 ` Florent Revest
2021-04-14 10:56 ` Florent Revest
2021-04-12 15:37 ` [PATCH bpf-next v3 2/6] bpf: Add a ARG_PTR_TO_CONST_STR argument type Florent Revest
2021-04-13 23:03 ` Andrii Nakryiko
2021-04-12 15:37 ` [PATCH bpf-next v3 3/6] bpf: Add a bpf_snprintf helper Florent Revest
2021-04-12 19:11 ` kernel test robot
2021-04-12 20:32 ` kernel test robot
2021-04-14 13:32 ` Florent Revest
2021-04-12 20:40 ` kernel test robot
2021-04-13 23:16 ` Andrii Nakryiko
2021-04-14 9:46 ` Florent Revest
2021-04-14 22:57 ` Andrii Nakryiko
2021-04-15 9:34 ` Florent Revest
2021-04-14 18:02 ` Geert Uytterhoeven
2021-04-14 18:30 ` Florent Revest
2021-04-14 22:58 ` Andrii Nakryiko
2021-04-15 7:18 ` Geert Uytterhoeven
2021-04-12 15:37 ` [PATCH bpf-next v3 4/6] libbpf: Initialize the bpf_seq_printf parameters array field by field Florent Revest
2021-04-13 23:18 ` Andrii Nakryiko
2021-04-12 15:37 ` [PATCH bpf-next v3 5/6] libbpf: Introduce a BPF_SNPRINTF helper macro Florent Revest
2021-04-13 23:18 ` Andrii Nakryiko
2021-04-12 15:37 ` [PATCH bpf-next v3 6/6] selftests/bpf: Add a series of tests for bpf_snprintf Florent Revest
2021-04-13 23:21 ` Andrii Nakryiko
2021-04-14 9:21 ` Florent Revest [this message]
2021-04-14 22:16 ` Andrii Nakryiko
2021-04-15 9:38 ` Florent Revest
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