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perf: fix hypervisor branch sampling permission check

PATCH In review Stephane Eranian 3 participants 3 messages Jun 6, 2013 – Jun 19, 2013 perf events

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Stephane Eranian

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#0 lore raw

PATCH 1/1 perf: fix hypervisor branch sampling permission check

Commit 2b923c8 perf/x86: Check branch sampling priv level in generic code was missing the check for the hypervisor (HV) priv level, so add it back.

With this patch, we get the following correct behavior:

  # echo 2 >/proc/sys/kernel/perf_event_paranoid 
  $ perf record -j any,k noploop 1
  Error:
  You may not have permission to collect stats.
  Consider tweaking /proc/sys/kernel/perf_event_paranoid:
   -1 - Not paranoid at all
    0 - Disallow raw tracepoint access for unpriv
    1 - Disallow cpu events for unpriv
    2 - Disallow kernel profiling for unpriv
   $ perf record -j any,hv noploop 1
   Error:
   You may not have permission to collect stats.
   Consider tweaking /proc/sys/kernel/perf_event_paranoid:
    -1 - Not paranoid at all
     0 - Disallow raw tracepoint access for unpriv
     1 - Disallow cpu events for unpriv
     2 - Disallow kernel profiling for unpriv
Signed-off-by Stephane Eranian <[email protected]>

---

kernel/events/core.c +2 -2
index 95edd5a..f0880fb 100644
@@ -6501,8 +6501,8 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 			 */
 			attr->branch_sample_type = mask;
 		}
-		/* kernel level capture: check permissions */
-		if ((mask & PERF_SAMPLE_BRANCH_KERNEL)
+		/* privileged levels capture (kernel, hv): check permissions */
+		if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
 		    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 			return -EACCES;
 	}
Acked-by on v1 1/1
#1 lore raw
Quoted 33 lines · Stephane Eranian

Commit 2b923c8 perf/x86: Check branch sampling priv level in generic code was missing the check for the hypervisor (HV) priv level, so add it back.

With this patch, we get the following correct behavior:

  # echo 2 >/proc/sys/kernel/perf_event_paranoid 
  $ perf record -j any,k noploop 1
  Error:
  You may not have permission to collect stats.
  Consider tweaking /proc/sys/kernel/perf_event_paranoid:
   -1 - Not paranoid at all
    0 - Disallow raw tracepoint access for unpriv
    1 - Disallow cpu events for unpriv
    2 - Disallow kernel profiling for unpriv
   $ perf record -j any,hv noploop 1
   Error:
   You may not have permission to collect stats.
   Consider tweaking /proc/sys/kernel/perf_event_paranoid:
    -1 - Not paranoid at all
     0 - Disallow raw tracepoint access for unpriv
     1 - Disallow cpu events for unpriv
     2 - Disallow kernel profiling for unpriv
Signed-off-by Stephane Eranian <[email protected]>

---

kernel/events/core.c +0 -0
index 95edd5a..f0880fb 100644

kernel/events/core.c static int perf_copy_attr(struct perf_event_attr __user *uattr, · line 6508

Quoted 10 lines
kernel/events/core.c +2 -2
@@ -6501,8 +6501,8 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 			 */
 			attr->branch_sample_type = mask;
 		}
-		/* kernel level capture: check permissions */
-		if ((mask & PERF_SAMPLE_BRANCH_KERNEL)
+		/* privileged levels capture (kernel, hv): check permissions */
+		if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
 		    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 			return -EACCES;
 	}
Acked-by Petr Matousek <[email protected]>
Signature · 1 line
Petr Matousek / Red Hat Security Response Team
merge bot
#2 lore raw

[tip:perf/core] perf: Fix hypervisor branch sampling permission check

In reply to Stephane Eranian
perf: Fix hypervisor branch sampling permission check
Commit-ID:  e712209a9e0b70e78b13847738eb66fe37412515
Gitweb:     http://git.kernel.org/tip/e712209a9e0b70e78b13847738eb66fe37412515
Author:     Stephane Eranian <[email protected]>
AuthorDate: Thu, 6 Jun 2013 11:02:04 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Wed, 19 Jun 2013 12:50:21 +0200

perf: Fix hypervisor branch sampling permission check

Commit 2b923c8 perf/x86: Check branch sampling priv level in generic code was missing the check for the hypervisor (HV) priv level, so add it back.

With this patch, we get the following correct behavior:

  # echo 2 >/proc/sys/kernel/perf_event_paranoid
  $ perf record -j any,k noploop 1
  Error:
  You may not have permission to collect stats.
  Consider tweaking /proc/sys/kernel/perf_event_paranoid:
   -1 - Not paranoid at all
    0 - Disallow raw tracepoint access for unpriv
    1 - Disallow cpu events for unpriv
    2 - Disallow kernel profiling for unpriv
   $ perf record -j any,hv noploop 1
   Error:
   You may not have permission to collect stats.
   Consider tweaking /proc/sys/kernel/perf_event_paranoid:
    -1 - Not paranoid at all
     0 - Disallow raw tracepoint access for unpriv
     1 - Disallow cpu events for unpriv
     2 - Disallow kernel profiling for unpriv
Signed-off-by Stephane Eranian <[email protected]>
Acked-by Petr Matousek <[email protected]>
Signed-off-by Peter Zijlstra <[email protected]>
Link http://lkml.kernel.org/r/20130606090204.GA3725@quad open here
Signed-off-by Ingo Molnar <[email protected]>
---
 kernel/events/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
kernel/events/core.c +2 -2
index d0e0d0d..aca95bc 100644
@@ -6573,8 +6573,8 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
 			 */
 			attr->branch_sample_type = mask;
 		}
-		/* kernel level capture: check permissions */
-		if ((mask & PERF_SAMPLE_BRANCH_KERNEL)
+		/* privileged levels capture (kernel, hv): check permissions */
+		if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
 		    && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 			return -EACCES;
 	}