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From: Igor Lubashev <ilubashe@akamai.com>
To: <linux-kernel@vger.kernel.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>,
	Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: 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>,
	Igor Lubashev <ilubashe@akamai.com>
Subject: [PATCH v2 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Date: Tue, 6 Aug 2019 23:35:56 -0400	[thread overview]
Message-ID: <f739900dede057b83a6e6ac5dee5fffb67f16e97.1565146171.git.ilubashe@akamai.com> (raw)
In-Reply-To: <cover.1565146171.git.ilubashe@akamai.com>

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>
---
 tools/perf/util/symbol.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 173f3378aaa0..046271103499 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -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"
@@ -890,7 +893,11 @@ bool symbol__restricted_filename(const char *filename,
 {
 	bool restricted = false;
 
-	if (symbol_conf.kptr_restrict) {
+	/* Per kernel/kallsyms.c:
+	 * we also restrict when perf_event_paranoid > 1 w/o CAP_SYSLOG
+	 */
+	if (symbol_conf.kptr_restrict ||
+	    (perf_event_paranoid() > 1 && !perf_cap__capable(CAP_SYSLOG))) {
 		char *r = realpath(filename, NULL);
 
 		if (r != NULL) {
@@ -2190,9 +2197,9 @@ 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);
 	}
-- 
2.7.4


WARNING: multiple messages have this Message-ID (diff)
From: Igor Lubashev <ilubashe@akamai.com>
To: <linux-kernel@vger.kernel.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>,
	Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Igor Lubashev <ilubashe@akamai.com>,
	James Morris <jmorris@namei.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Ingo Molnar <mingo@redhat.com>,
	Namhyung Kim <namhyung@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks
Date: Tue, 6 Aug 2019 23:35:56 -0400	[thread overview]
Message-ID: <f739900dede057b83a6e6ac5dee5fffb67f16e97.1565146171.git.ilubashe@akamai.com> (raw)
In-Reply-To: <cover.1565146171.git.ilubashe@akamai.com>

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>
---
 tools/perf/util/symbol.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 173f3378aaa0..046271103499 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -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"
@@ -890,7 +893,11 @@ bool symbol__restricted_filename(const char *filename,
 {
 	bool restricted = false;
 
-	if (symbol_conf.kptr_restrict) {
+	/* Per kernel/kallsyms.c:
+	 * we also restrict when perf_event_paranoid > 1 w/o CAP_SYSLOG
+	 */
+	if (symbol_conf.kptr_restrict ||
+	    (perf_event_paranoid() > 1 && !perf_cap__capable(CAP_SYSLOG))) {
 		char *r = realpath(filename, NULL);
 
 		if (r != NULL) {
@@ -2190,9 +2197,9 @@ 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);
 	}
-- 
2.7.4


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  parent reply	other threads:[~2019-08-07  3:36 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-07  3:35 [PATCH v2 0/4] perf: Use capabilities instead of uid and euid Igor Lubashev
2019-08-07  3:35 ` Igor Lubashev
2019-08-07  3:35 ` [PATCH v2 1/4] perf: Add capability-related utilities Igor Lubashev
2019-08-07  3:35   ` Igor Lubashev
2019-08-07  3:35 ` [PATCH v2 2/4] perf: Use CAP_SYS_ADMIN with perf_event_paranoid checks Igor Lubashev
2019-08-07  3:35   ` Igor Lubashev
2019-08-07 11:44   ` Alexey Budankov
2019-08-07 11:44     ` Alexey Budankov
2019-08-07 11:46   ` Jiri Olsa
2019-08-07 11:46     ` Jiri Olsa
2019-08-07 14:56     ` Lubashev, Igor
2019-08-07 14:56       ` Lubashev, Igor
2019-08-07  3:35 ` Igor Lubashev [this message]
2019-08-07  3:35   ` [PATCH v2 3/4] perf: Use CAP_SYSLOG with kptr_restrict checks Igor Lubashev
2019-08-07  3:35 ` [PATCH v2 4/4] perf: Use CAP_SYS_ADMIN instead of euid==0 with ftrace Igor Lubashev
2019-08-07  3:35   ` Igor Lubashev

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