On 26/06/18 18:24, Alexey Budankov wrote:
Hi,
On 26.06.2018 18:36, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <[email protected]>
To enable per-PMU access controls in a following patch first move all call
sites of perf_paranoid_kernel() to after the event has been created.
Signed-off-by: Tvrtko Ursulin <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Madhavan Srinivasan <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Alexey Budankov <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
kernel/events/core.c | 36 ++++++++++++++++++++++--------------
1 file changed, 22 insertions(+), 14 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f490caca9aa4..12de95b0472e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10189,10 +10189,6 @@ static int perf_copy_attr(struct perf_event_attr
__user *uattr,
*/
attr->branch_sample_type = mask;
}
- /* privileged levels capture (kernel, hv): check permissions */
- if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
- && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
- return -EACCES;
}
if (attr->sample_type & PERF_SAMPLE_REGS_USER) {
@@ -10409,11 +10405,6 @@ SYSCALL_DEFINE5(perf_event_open,
if (err)
return err;
- if (!attr.exclude_kernel) {
- if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
- return -EACCES;
- }
-
if (attr.namespaces) {
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
@@ -10427,11 +10418,6 @@ SYSCALL_DEFINE5(perf_event_open,
return -EINVAL;
}
- /* Only privileged users can get physical addresses */
- if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) &&
- perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
- return -EACCES;
-
/*
* In cgroup mode, the pid argument is used to pass the fd
* opened to the cgroup directory in cgroupfs. The cpu argument
@@ -10501,6 +10487,28 @@ SYSCALL_DEFINE5(perf_event_open,
goto err_cred;
}
+ if (!attr.exclude_kernel) {
+ if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) {
+ err = -EACCES;
I would separate this combined permissions check into a function e.g.
static bool perf_test_pmu_paranoid(const struct pmu *pmu, int *err) to avoid
code duplication.
My thinking was for this to be as mechanical (code movement) as
possible, but I can consider it.
Regards,
Tvrtko
+ goto err_alloc;
+ }
+ }
+
+ /* Only privileged users can get physical addresses */
+ if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) &&
+ perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) {
+ err = -EACCES;
+ goto err_alloc;
+ }
+
+ /* privileged levels capture (kernel, hv): check permissions */
+ if ((attr.sample_type & PERF_SAMPLE_BRANCH_STACK) &&
+ (attr.branch_sample_type & PERF_SAMPLE_BRANCH_PERM_PLM) &&
+ perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) {
+ err = -EACCES;
+ goto err_alloc;
+ }
+
if (is_sampling_event(event)) {
if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
err = -EOPNOTSUPP;
