[tip: perf/urgent] perf/core: Take over CAP_SYS_PTRACE creds to CAP_PERFMON capability
From: tip-bot2 for Alexey Budankov
Date: Thu Aug 06 2020 - 13:14:41 EST
The following commit has been merged into the perf/urgent branch of tip:
Commit-ID: 45fd22da97c6125d8d0d35bd1791e7c0c4175279
Gitweb: https://git.kernel.org/tip/45fd22da97c6125d8d0d35bd1791e7c0c4175279
Author: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 05 Aug 2020 10:56:56 +03:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Thu, 06 Aug 2020 15:03:20 +02:00
perf/core: Take over CAP_SYS_PTRACE creds to CAP_PERFMON capability
Open access to per-process monitoring for CAP_PERFMON only
privileged processes [1]. Extend ptrace_may_access() check
in perf_events subsystem with perfmon_capable() to simplify
user experience and make monitoring more secure by reducing
attack surface.
[1] https://lore.kernel.org/lkml/7776fa40-6c65-2aa6-1322-eb3a01201000@xxxxxxxxxxxxxxx/
Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/6e8392ff-4732-0012-2949-e1587709f0f6@xxxxxxxxxxxxxxx
---
kernel/events/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 78e69e1..41e0cef 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11689,7 +11689,7 @@ SYSCALL_DEFINE5(perf_event_open,
goto err_task;
/*
- * Reuse ptrace permission checks for now.
+ * Preserve ptrace permission check for backwards compatibility.
*
* We must hold exec_update_mutex across this and any potential
* perf_install_in_context() call for this new event to
@@ -11697,7 +11697,7 @@ SYSCALL_DEFINE5(perf_event_open,
* perf_event_exit_task() that could imply).
*/
err = -EACCES;
- if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS))
+ if (!perfmon_capable() && !ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS))
goto err_cred;
}