Commit 8859aede authored Aug 26, 2019 by Igor Lubashev Committed by Arnaldo Carvalho de Melo Aug 28, 2019

perf symbols: Use CAP_SYSLOG with kptr_restrict checks



The kernel is using CAP_SYSLOG capability instead of uid==0 and euid==0
when checking kptr_restrict. Make perf do the same.

Also, the kernel is a more restrictive than "no restrictions" in case of
kptr_restrict==0, so add the same logic to perf.

Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1566869956-7154-5-git-send-email-ilubashe@akamai.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent aa97293f

tools/perf/util/symbol.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@
		#include <stdlib.h>
		#include <stdio.h>
		#include <string.h>
		#include <linux/capability.h>
		#include <linux/kernel.h>
		#include <linux/mman.h>
		#include <linux/time64.h>
		@@ -15,8 +16,10 @@
		#include <inttypes.h>
		#include "annotate.h"
		#include "build-id.h"
		#include "cap.h"
		#include "util.h"
		#include "debug.h"
		#include "event.h"
		#include "machine.h"
		#include "map.h"
		#include "symbol.h"
		@@ -2195,13 +2198,19 @@ static bool symbol__read_kptr_restrict(void)
		char line[8];

		if (fgets(line, sizeof(line), fp) != NULL)
		value = ((geteuid() != 0) \|\| (getuid() != 0)) ?
		(atoi(line) != 0) :
		(atoi(line) == 2);
		value = perf_cap__capable(CAP_SYSLOG) ?
		(atoi(line) >= 2) :
		(atoi(line) != 0);

		fclose(fp);
		}

		/* Per kernel/kallsyms.c:
		* we also restrict when perf_event_paranoid > 1 w/o CAP_SYSLOG
		*/
		if (perf_event_paranoid() > 1 && !perf_cap__capable(CAP_SYSLOG))
		value = true;

		return value;
		}

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