Commit 45fd22da authored Aug 05, 2020 by Alexey Budankov Committed by Ingo Molnar Aug 06, 2020

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@linux.intel.com/



Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/6e8392ff-4732-0012-2949-e1587709f0f6@linux.intel.com

parent 2324d50d

kernel/events/core.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

Admin message