From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: linux-man <linux-man@vger.kernel.org>,
James Morris <jmorris@namei.org>, Serge Hallyn <serge@hallyn.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
Peter Zijlstra <peterz@infradead.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andi Kleen <ak@linux.intel.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Michael Kerrisk <mtk.manpages@gmail.com>
Subject: Re: [PATCH v1] perf_event_open.2: update the man page with CAP_PERFMON related information
Date: Tue, 27 Oct 2020 10:25:26 +0100 [thread overview]
Message-ID: <CAKgNAkirXKh6VocM7-gwvC1CoDgqV7NjpU5OSVvXJX9mwiNnBg@mail.gmail.com> (raw)
In-Reply-To: <e3ff6ff2-8fa5-de27-3bc4-f578b6957de8@linux.intel.com>
Hi Alexei,
Would you be able to refresh this patch and resend please?
Thnks,
Michael
On Mon, 24 Aug 2020 at 22:17, Alexey Budankov
<alexey.budankov@linux.intel.com> wrote:
>
> Hi Michael,
>
> On 23.08.2020 20:28, Michael Kerrisk (man-pages) wrote:
> > Hello Alexey,
> >
> > Could you look at the question below and update the patch.
> >
> > On 2/17/20 9:18 AM, Alexey Budankov wrote:
> >>
> >> Extend perf_event_open 2 man page with the information about
> >> CAP_PERFMON capability designed to secure performance monitoring
> >> and observability operation in a system according to the principle
> >> of least privilege [1] (POSIX IEEE 1003.1e, 2.2.2.39).
> >>
> >> [1] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf
> >>
> >> Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
> >> ---
> >> man2/perf_event_open.2 | 27 +++++++++++++++++++++++++++
> >> 1 file changed, 27 insertions(+)
> >>
> >> diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
> >> index 89d267c02..e9aab2ca1 100644
> >> --- a/man2/perf_event_open.2
> >> +++ b/man2/perf_event_open.2
> >> @@ -98,6 +98,8 @@ when running on the specified CPU.
> >> .BR "pid == \-1" " and " "cpu >= 0"
> >> This measures all processes/threads on the specified CPU.
> >> This requires
> >> +.B CAP_PERFMON
> >> +or
> >> .B CAP_SYS_ADMIN
> >> capability or a
> >> .I /proc/sys/kernel/perf_event_paranoid
> >> @@ -2920,6 +2922,8 @@ to hold the result.
> >> This allows attaching a Berkeley Packet Filter (BPF)
> >> program to an existing kprobe tracepoint event.
> >> You need
> >> +.B CAP_PERFMON
> >> +or
> >> .B CAP_SYS_ADMIN
> >> privileges to use this ioctl.
> >> .IP
> >> @@ -2962,6 +2966,8 @@ have multiple events attached to a tracepoint.
> >> Querying this value on one tracepoint event returns the id
> >> of all BPF programs in all events attached to the tracepoint.
> >> You need
> >> +.B CAP_PERFMON
> >> +or
> >> .B CAP_SYS_ADMIN
> >> privileges to use this ioctl.
> >> .IP
> >> @@ -3170,6 +3176,8 @@ it was expecting.
> >> .TP
> >> .B EACCES
> >> Returned when the requested event requires
> >> +.B CAP_PERFMON
> >> +or
> >> .B CAP_SYS_ADMIN
> >> permissions (or a more permissive perf_event paranoid setting).
> >> Some common cases where an unprivileged process
> >> @@ -3291,6 +3299,8 @@ setting is specified.
> >> It can also happen, as with
> >> .BR EACCES ,
> >> when the requested event requires
> >> +.B CAP_PERFMON
> >> +or
> >> .B CAP_SYS_ADMIN
> >> permissions (or a more permissive perf_event paranoid setting).
> >> This includes setting a breakpoint on a kernel address,
> >> @@ -3321,6 +3331,23 @@ The official way of knowing if
> >> support is enabled is checking
> >> for the existence of the file
> >> .IR /proc/sys/kernel/perf_event_paranoid .
> >> +.PP
> >> +.B CAP_PERFMON
> >> +capability (since Linux X.Y) provides secure approach to
> >
> > What's the version?
>
> It's since Linux 5.8 .
>
> >
> >> +performance monitoring and observability operations in a system
> >> +according to the principal of least privilege (POSIX IEEE 1003.1e).
> >> +Accessing system performance monitoring and observability operations
> >> +using
> >> +.B CAP_PERFMON
> >> +capability singly, without the rest of
> >> +.B CAP_SYS_ADMIN
> >> +credentials, excludes chances to misuse the credentials and makes
> >
> > I think that wording like "using CAP_PERFMON rather than the much
> > more powerful CAP_SYS_ADMIN..."
>
> Sounds good to me like this, or similar:
>
> "Accessing system performance monitoring and observability operations
> using CAP_PERFMON rather than the much more powerful CAP_SYS_ADMIN
> excludes chances to misuse credentials and makes operations more
> secure."
>
> >
> >> +the operations more secure.
> >> +.B CAP_SYS_ADMIN
> >> +usage for secure system performance monitoring and observability
> >> +is discouraged with respect to
> >> +.B CAP_PERFMON
> >> +capability.
> >> .SH BUGS
> >> The
> >> .B F_SETOWN_EX
> >
> > Thanks,
> >
> > Michael
> >
>
> Thanks,
> Alexei
>
> P.S.
> I am on vacations till 08/31.
> Please expect delay in response.
>
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
next prev parent reply other threads:[~2020-10-27 9:25 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-17 8:18 [PATCH v1] perf_event_open.2: update the man page with CAP_PERFMON related information Alexey Budankov
2020-08-23 17:28 ` Michael Kerrisk (man-pages)
2020-08-24 20:17 ` Alexey Budankov
2020-10-27 9:25 ` Michael Kerrisk (man-pages) [this message]
2020-10-27 10:34 ` Alexey Budankov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAKgNAkirXKh6VocM7-gwvC1CoDgqV7NjpU5OSVvXJX9mwiNnBg@mail.gmail.com \
--to=mtk.manpages@gmail.com \
--cc=acme@kernel.org \
--cc=ak@linux.intel.com \
--cc=alexey.budankov@linux.intel.com \
--cc=jmorris@namei.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-man@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=sds@tycho.nsa.gov \
--cc=serge@hallyn.com \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).