Re: [PATCH v2 1/4] bpf: Add support for reading user pointers

[Masami Hiramatsu]

On Tue, 7 May 2019 01:10:45 +0200
Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:

> On 05/06/2019 09:57 PM, Joel Fernandes wrote:
> > On Mon, May 06, 2019 at 09:11:19PM +0200, Daniel Borkmann wrote:
> >> On 05/06/2019 08:31 PM, Joel Fernandes (Google) wrote:
> >>> The eBPF based opensnoop tool fails to read the file path string passed
> >>> to the do_sys_open function. This is because it is a pointer to
> >>> userspace address and causes an -EFAULT when read with
> >>> probe_kernel_read. This is not an issue when running the tool on x86 but
> >>> is an issue on arm64. This patch adds a new bpf function call based
> >>> which calls the recently proposed probe_user_read function [1].
> >>> Using this function call from opensnoop fixes the issue on arm64.
> >>>
> >>> [1] https://lore.kernel.org/patchwork/patch/1051588/
> >>>
> >>> Cc: Michal Gregorczyk <michalgr@xxxxxxxx>
> >>> Cc: Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>
> >>> Cc: Mohammad Husain <russoue@xxxxxxxxx>
> >>> Cc: Qais Yousef <qais.yousef@xxxxxxx>
> >>> Cc: Srinivas Ramana <sramana@xxxxxxxxxxxxxx>
> >>> Cc: duyuchao <yuchao.du@xxxxxxxxxx>
> >>> Cc: Manjo Raja Rao <linux@xxxxxxxxxxxxxxxx>
> >>> Cc: Karim Yaghmour <karim.yaghmour@xxxxxxxxxxx>
> >>> Cc: Tamir Carmeli <carmeli.tamir@xxxxxxxxx>
> >>> Cc: Yonghong Song <yhs@xxxxxx>
> >>> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> >>> Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
> >>> Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> >>> Cc: Peter Ziljstra <peterz@xxxxxxxxxxxxx>
> >>> Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
> >>> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> >>> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> >>> Cc: kernel-team@xxxxxxxxxxx
> >>> Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> >>> ---
> >>> Masami, could you carry these patches in the series where are you add
> >>> probe_user_read function?
> >>>
> >>> Previous submissions is here:
> >>> https://lore.kernel.org/patchwork/patch/1069552/
> >>> v1->v2: split tools uapi sync into separate commit, added deprecation
> >>> warning for old bpf_probe_read function.
> >>
> >> Please properly submit this series to bpf tree once the base
> >> infrastructure from Masami is upstream.
> > 
> > Could you clarify what do you mean by "properly submit this series to bpf
> > tree" mean? bpf@xxxxxxxxxxxxxxx is CC'd.
> 
> Yeah, send the BPF series to bpf@xxxxxxxxxxxxxxx once Masami's patches have
> hit mainline, and we'll then route yours as fixes the usual path through
> bpf tree.

OK, then I focus on my series. Keep this series separated.
Thank you!

> 
> >> This series here should
> >> also fix up all current probe read usage under samples/bpf/ and
> >> tools/testing/selftests/bpf/.
> > 
> > Ok. Agreed, will do that.
> 
> Great, thanks!
> Daniel


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>