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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH RFC v3 bpf-next 2/4] bpf: Add bpf_copy_from_user() helper.
Date: Tue, 30 Jun 2020 11:23:07 -0700	[thread overview]
Message-ID: <CAEf4BzbfXajuL-1VLBUJsC3P796s2hk9oYGveYG5QnS2=YoN-A@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQ+ubYj8yA1_cO3aw-trShTHBRMJxSvZrLW75i8fM=mpvQ@mail.gmail.com>

On Mon, Jun 29, 2020 at 5:28 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
> On Thu, Jun 18, 2020 at 3:33 PM Andrii Nakryiko
> <andrii.nakryiko@gmail.com> wrote:
> > > + *
> > > + * int bpf_copy_from_user(void *dst, u32 size, const void *user_ptr)
> >
> > Can we also add bpf_copy_str_from_user (or bpf_copy_from_user_str,
> > whichever makes more sense) as well?
> Those would have to wait. I think strings need better long term design.
> That would be separate patches.

I agree that it would be nice to have better support for strings, long
term, but that's beside the point.

I think bpf_copy_from_user_str() is a must have right now as a
sleepable counterpart to bpf_probe_read_user_str(), just like
bpf_copy_from_user() is a sleepable variant of bpf_probe_read_user().
Look at progs/strobemeta.h, it does bpf_probe_read_user_str() to get
user-space zero-terminated strings. It's well defined interface and
behavior. There is nothing extra needed beyond a sleepable variant of
bpf_probe_read_user_str() to allow Strobemeta reliably fetch data from
user-space from inside a sleepable BPF program.

  reply	other threads:[~2020-06-30 18:23 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11 22:23 [PATCH RFC v3 bpf-next 0/4] bpf: Introduce minimal support for sleepable progs Alexei Starovoitov
2020-06-11 22:23 ` [PATCH RFC v3 bpf-next 1/4] bpf: Introduce sleepable BPF programs Alexei Starovoitov
2020-06-11 22:29   ` Alexei Starovoitov
2020-06-12  0:04     ` Paul E. McKenney
2020-06-12  2:13       ` Alexei Starovoitov
2020-06-12  3:40         ` Paul E. McKenney
2020-06-11 22:23 ` [PATCH RFC v3 bpf-next 2/4] bpf: Add bpf_copy_from_user() helper Alexei Starovoitov
2020-06-18 22:33   ` Andrii Nakryiko
2020-06-30  0:28     ` Alexei Starovoitov
2020-06-30 18:23       ` Andrii Nakryiko [this message]
2020-06-30 18:53         ` Alexei Starovoitov
2020-06-11 22:23 ` [PATCH RFC v3 bpf-next 3/4] libbpf: support sleepable progs Alexei Starovoitov
2020-06-18 22:34   ` Andrii Nakryiko
2020-06-11 22:23 ` [PATCH RFC v3 bpf-next 4/4] selftests/bpf: basic sleepable tests Alexei Starovoitov
2020-06-18 22:43   ` Andrii Nakryiko

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