linux-kernel - [tip:perf/urgent] perf evsel: Improve EPERM error handling in open

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <tip-0gc4rdpg8d025r5not8s8028@git.kernel.org>
Date:	Fri, 13 May 2016 02:18:25 -0700
From:	tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	keescook@...omium.org, acme@...hat.com, hpa@...or.com,
	mingo@...nel.org, dsahern@...il.com, wangnan0@...wei.com,
	adrian.hunter@...el.com, linux-kernel@...r.kernel.org,
	jolsa@...nel.org, tglx@...utronix.de,
	torvalds@...ux-foundation.org, luto@...nel.org,
	peterz@...radead.org, mhiramat@...nel.org, namhyung@...nel.org
Subject: [tip:perf/urgent] perf evsel: Improve EPERM error handling in
 open_strerror()

Commit-ID:  7d173913a6420f2818afeca70b268f064441f69b
Gitweb:     http://git.kernel.org/tip/7d173913a6420f2818afeca70b268f064441f69b
Author:     Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Thu, 12 May 2016 15:44:55 -0300
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Thu, 12 May 2016 15:44:55 -0300

perf evsel: Improve EPERM error handling in open_strerror()

We were showing a hardcoded default value for the kernel.perf_event_paranoid
sysctl, now that it became more paranoid (1 -> 2 [1]), this would need to be
updated, instead show the current value:

  [acme@...et linux]$ perf record ls
  Error:
  You may not have permission to collect stats.

  Consider tweaking /proc/sys/kernel/perf_event_paranoid,
  which controls use of the performance events system by
  unprivileged users (without CAP_SYS_ADMIN).

  The current value is 2:

    -1: Allow use of (almost) all events by all users
  >= 0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
  >= 1: Disallow CPU event access by users without CAP_SYS_ADMIN
  >= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN
  [acme@...et linux]$

[1] 0161028b7c8a ("perf/core: Change the default paranoia level to 2")

Reported-by: Ingo Molnar <mingo@...nel.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-0gc4rdpg8d025r5not8s8028@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/evsel.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 738ce22..a5f339d 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2382,12 +2382,13 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target,
 		 "Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n"
 		 "which controls use of the performance events system by\n"
 		 "unprivileged users (without CAP_SYS_ADMIN).\n\n"
-		 "The default value is 1:\n\n"
+		 "The current value is %d:\n\n"
 		 "  -1: Allow use of (almost) all events by all users\n"
 		 ">= 0: Disallow raw tracepoint access by users without CAP_IOC_LOCK\n"
 		 ">= 1: Disallow CPU event access by users without CAP_SYS_ADMIN\n"
 		 ">= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN",
-				 target->system_wide ? "system-wide " : "");
+				 target->system_wide ? "system-wide " : "",
+				 perf_event_paranoid());
 	case ENOENT:
 		return scnprintf(msg, size, "The %s event is not supported.",
 				 perf_evsel__name(evsel));