From: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
To: Igor Lubashev <ilubashe@akamai.com>
Cc: linux-kernel@vger.kernel.org, Jiri Olsa <jolsa@redhat.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Namhyung Kim <namhyung@kernel.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
linux-arm-kernel@lists.infradead.org,
James Morris <jmorris@namei.org>
Subject: Re: [PATCH v3 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks
Date: Mon, 12 Aug 2019 17:15:57 -0300 [thread overview]
Message-ID: <20190812201557.GF9280@kernel.org> (raw)
In-Reply-To: <20190812200134.GE9280@kernel.org>
Em Mon, Aug 12, 2019 at 05:01:34PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, Aug 07, 2019 at 10:44:15AM -0400, Igor Lubashev escreveu:
> > +++ b/tools/perf/util/evsel.c
> > @@ -279,7 +279,7 @@ struct evsel *perf_evsel__new_idx(struct perf_event_attr *attr, int idx)
>
> > static bool perf_event_can_profile_kernel(void)
> > {
> > - return geteuid() == 0 || perf_event_paranoid() == -1;
> > + return perf_event_paranoid_check(-1);
> > }
>
> While looking at your changes I think the pre-existing code is wrong,
> i.e. the check in sys_perf_event_open(), in the kernel is:
>
> if (!attr.exclude_kernel) {
> if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
> return -EACCES;
> }
>
> And:
>
> static inline bool perf_paranoid_kernel(void)
> {
> return sysctl_perf_event_paranoid > 1;
> }
>
> So we have to change that perf_event_paranoit_check(-1) to pass 1
> instead?
>
> bool perf_event_paranoid_check(int max_level)
> {
> return perf_cap__capable(CAP_SYS_ADMIN) ||
> perf_event_paranoid() <= max_level;
> }
>
> Also you defined perf_cap__capable(anything) as:
>
> #ifdef HAVE_LIBCAP_SUPPORT
>
> #include <sys/capability.h>
>
> bool perf_cap__capable(cap_value_t cap);
>
> #else
>
> static inline bool perf_cap__capable(int cap __maybe_unused)
> {
> return false;
> }
>
> #endif /* HAVE_LIBCAP_SUPPORT */
>
>
> I think we should have:
>
> #else
>
> static inline bool perf_cap__capable(int cap __maybe_unused)
> {
> return geteuid() == 0;
> }
>
> #endif /* HAVE_LIBCAP_SUPPORT */
>
> Right?
>
> So I am removing the introduction of perf_cap__capable() from the first
> patch you sent, leaving it with _only_ the feature detection part, using
> that feature detection to do anything is then moved to a separate patch,
> after we finish this discussion about what we should fallback to when
> libcap-devel isn't available, i.e. we should use the previous checks,
> etc.
So, please take a look at the tmp.perf/cap branch in my git repo:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/log/?h=tmp.perf/cap
I split the patch and made perf_cap__capable() fallback to 'return
geteuid() == 0;' when libcap-devel isn't available, i.e. keep the
checks made prior to your patchset.
Jiri, can I keep your Acked-by?
- Arnaldo
next prev parent reply other threads:[~2019-08-12 20:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 14:44 [PATCH v3 0/4] perf: Use capabilities instead of uid and euid Igor Lubashev
2019-08-07 14:44 ` [PATCH v3 1/4] perf: Add capability-related utilities Igor Lubashev
2019-08-12 19:43 ` Arnaldo Carvalho de Melo
2019-08-15 9:24 ` [tip:perf/core] tools build: Add capability-related feature detection tip-bot for Igor Lubashev
2019-08-15 9:25 ` [tip:perf/core] perf tools: Add helpers to use capabilities if present tip-bot for Igor Lubashev
2019-08-07 14:44 ` [PATCH v3 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks Igor Lubashev
2019-08-12 20:01 ` Arnaldo Carvalho de Melo
2019-08-12 20:15 ` Arnaldo Carvalho de Melo [this message]
2019-08-12 22:33 ` Lubashev, Igor
2019-08-13 13:20 ` Arnaldo Carvalho de Melo
2019-08-07 14:44 ` [PATCH v3 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks Igor Lubashev
2019-08-14 18:04 ` Mathieu Poirier
2019-08-14 18:48 ` Arnaldo Carvalho de Melo
2019-08-14 18:52 ` Arnaldo Carvalho de Melo
2019-08-14 20:02 ` Lubashev, Igor
2019-08-15 15:01 ` Mathieu Poirier
2019-08-15 20:16 ` Mathieu Poirier
2019-08-15 21:42 ` Arnaldo Carvalho de Melo
2019-08-19 16:51 ` Mathieu Poirier
2019-08-19 22:22 ` Lubashev, Igor
2019-08-20 16:57 ` Mathieu Poirier
2019-08-20 17:13 ` Arnaldo Carvalho de Melo
2019-08-27 1:58 ` Lubashev, Igor
2019-08-15 22:27 ` Lubashev, Igor
2019-08-07 14:44 ` [PATCH v3 4/4] perf: Use CAP_SYS_ADMIN instead of euid==0 with ftrace Igor Lubashev
2019-08-12 20:22 ` Arnaldo Carvalho de Melo
2019-08-12 20:27 ` Arnaldo Carvalho de Melo
2019-08-12 20:29 ` Arnaldo Carvalho de Melo
2019-08-12 21:42 ` Mathieu Poirier
2019-08-13 13:23 ` Arnaldo Carvalho de Melo
2019-08-13 16:35 ` Mathieu Poirier
2019-08-15 9:27 ` [tip:perf/core] perf ftrace: Use CAP_SYS_ADMIN instead of euid==0 tip-bot for Igor Lubashev
2019-08-12 9:13 ` [PATCH v3 0/4] perf: Use capabilities instead of uid and euid Jiri Olsa
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=20190812201557.GF9280@kernel.org \
--to=arnaldo.melo@gmail.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=alexey.budankov@linux.intel.com \
--cc=ilubashe@akamai.com \
--cc=jmorris@namei.org \
--cc=jolsa@redhat.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.poirier@linaro.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=suzuki.poulose@arm.com \
/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).