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From: Alexey Budankov <alexey.budankov@linux.intel.com>
To: James Morris <jmorris@namei.org>, Serge Hallyn <serge@hallyn.com>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Peter Zijlstra <peterz@infradead.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	"joonas.lahtinen@linux.intel.com"
	<joonas.lahtinen@linux.intel.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Will Deacon <will@kernel.org>, Paul Mackerras <paulus@samba.org>,
	Helge Deller <deller@gmx.de>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>,
	Stephane Eranian <eranian@google.com>,
	Igor Lubashev <ilubashe@akamai.com>, Jiri Olsa <jolsa@redhat.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"selinux@vger.kernel.org" <selinux@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"linux-parisc@vger.kernel.org" <linux-parisc@vger.kernel.org>,
	oprofile-list@lists.sf.net,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	linux-man@vger.kernel.org
Subject: [PATCH v7 05/12] drm/i915/perf: open access for CAP_PERFMON privileged process
Date: Mon, 17 Feb 2020 11:08:46 +0300
Message-ID: <8b408c10-9bb0-4b08-8681-93c0f4a1132e@linux.intel.com> (raw)
In-Reply-To: <c8de937a-0b3a-7147-f5ef-69f467e87a13@linux.intel.com>


Open access to i915_perf monitoring for CAP_PERFMON privileged process.
Providing the access under CAP_PERFMON capability singly, without the
rest of CAP_SYS_ADMIN credentials, excludes chances to misuse the
credentials and makes operation more secure.

CAP_PERFMON implements the principal of least privilege for performance
monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
principle of least privilege: A security design principle that states
that a process or program be granted only those privileges (e.g.,
capabilities) necessary to accomplish its legitimate function, and only
for the time that such privileges are actually required)

For backward compatibility reasons access to i915_events subsystem
remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
usage for secure i915_events monitoring is discouraged with respect to
CAP_PERFMON capability.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_perf.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 0f556d80ba36..a3f32bd0aa47 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -3378,10 +3378,10 @@ i915_perf_open_ioctl_locked(struct i915_perf *perf,
 	/* Similar to perf's kernel.perf_paranoid_cpu sysctl option
 	 * we check a dev.i915.perf_stream_paranoid sysctl option
 	 * to determine if it's ok to access system wide OA counters
-	 * without CAP_SYS_ADMIN privileges.
+	 * without CAP_PERFMON or CAP_SYS_ADMIN privileges.
 	 */
 	if (privileged_op &&
-	    i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+	    i915_perf_stream_paranoid && !perfmon_capable()) {
 		DRM_DEBUG("Insufficient privileges to open i915 perf stream\n");
 		ret = -EACCES;
 		goto err_ctx;
@@ -3574,9 +3574,8 @@ static int read_properties_unlocked(struct i915_perf *perf,
 			} else
 				oa_freq_hz = 0;
 
-			if (oa_freq_hz > i915_oa_max_sample_rate &&
-			    !capable(CAP_SYS_ADMIN)) {
-				DRM_DEBUG("OA exponent would exceed the max sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without root privileges\n",
+			if (oa_freq_hz > i915_oa_max_sample_rate && !perfmon_capable()) {
+				DRM_DEBUG("OA exponent would exceed the max sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without CAP_PERFMON or CAP_SYS_ADMIN privileges\n",
 					  i915_oa_max_sample_rate);
 				return -EACCES;
 			}
@@ -3997,7 +3996,7 @@ int i915_perf_add_config_ioctl(struct drm_device *dev, void *data,
 		return -EINVAL;
 	}
 
-	if (i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
 		DRM_DEBUG("Insufficient privileges to add i915 OA config\n");
 		return -EACCES;
 	}
@@ -4144,7 +4143,7 @@ int i915_perf_remove_config_ioctl(struct drm_device *dev, void *data,
 		return -ENOTSUPP;
 	}
 
-	if (i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
 		DRM_DEBUG("Insufficient privileges to remove i915 OA config\n");
 		return -EACCES;
 	}
-- 
2.20.1



  parent reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-17  8:02 [PATCH v7 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Alexey Budankov
2020-02-17  8:06 ` [PATCH v7 01/12] capabilities: introduce CAP_PERFMON to kernel and user space Alexey Budankov
2020-02-18 18:22   ` Stephen Smalley
2020-02-18 19:21   ` James Morris
2020-02-19  7:54     ` Alexey Budankov
2020-02-17  8:06 ` [PATCH v7 02/12] perf/core: open access to the core for CAP_PERFMON privileged process Alexey Budankov
2020-02-18 19:22   ` James Morris
2020-02-17  8:07 ` [PATCH v7 03/12] perf/core: open access to probes " Alexey Budankov
2020-02-18 19:22   ` James Morris
2020-02-17  8:08 ` [PATCH v7 04/12] perf tool: extend Perf tool with CAP_PERFMON capability support Alexey Budankov
2020-02-18 19:24   ` James Morris
2020-02-17  8:08 ` Alexey Budankov [this message]
2020-02-18 19:25   ` [PATCH v7 05/12] drm/i915/perf: open access for CAP_PERFMON privileged process James Morris
2020-02-17  8:09 ` [PATCH v7 06/12] trace/bpf_trace: " Alexey Budankov
2020-02-18 19:25   ` James Morris
2020-02-17  8:10 ` [PATCH v7 07/12] powerpc/perf: " Alexey Budankov
2020-02-18 19:28   ` James Morris
2020-02-17  8:10 ` [PATCH v7 08/12] parisc/perf: " Alexey Budankov
2020-02-18 19:29   ` James Morris
2020-02-17  8:11 ` [PATCH v7 09/12] drivers/perf: " Alexey Budankov
2020-02-18 19:43   ` James Morris
2020-02-17  8:12 ` [PATCH v7 10/12] drivers/oprofile: " Alexey Budankov
2020-02-18 19:44   ` James Morris
2020-02-17  8:12 ` [PATCH v7 11/12] doc/admin-guide: update perf-security.rst with CAP_PERFMON information Alexey Budankov
2020-02-17  8:13 ` [PATCH v7 12/12] doc/admin-guide: update kernel.rst " Alexey Budankov
2020-02-25  9:55 ` [PATCH v7 00/12] Introduce CAP_PERFMON to secure system performance monitoring and observability Alexey Budankov
2020-03-02  0:19   ` [Intel-gfx] " Serge Hallyn
2020-03-02 19:44     ` James Morris
2020-03-26 23:28     ` James Morris

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