From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Igor Lubashev <ilubashe@akamai.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
linux-kernel@vger.kernel.org, James Morris <jmorris@namei.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks
Date: Mon, 12 Aug 2019 17:01:34 -0300 [thread overview]
Message-ID: <20190812200134.GE9280@kernel.org> (raw)
In-Reply-To: <ad56df5452eeafb99dda9fc3d30f0f487aace503.1565188228.git.ilubashe@akamai.com>
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.
- Arnaldo
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-08-12 20:01 UTC|newest]
Thread overview: 30+ 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
2019-08-07 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 [this message]
2019-08-12 20:15 ` Arnaldo Carvalho de Melo
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
2019-08-12 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=20190812200134.GE9280@kernel.org \
--to=acme@kernel.org \
--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).