FROMLIST: security,perf: Allow further restriction of perf_event_open
When kernel.perf_event_open is set to 3 (or greater), disallow all
access to performance events by users without CAP_SYS_ADMIN.
Add a Kconfig symbol CONFIG_SECURITY_PERF_EVENTS_RESTRICT that
makes this value the default.
This is based on a similar feature in grsecurity
(CONFIG_GRKERNSEC_PERF_HARDEN). This version doesn't include making
the variable read-only. It also allows enabling further restriction
at run-time regardless of whether the default is changed.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Bug: 29054680
Patchset: perf-lockdown
(patch from https://lkml.org/lkml/2016/1/11/587)
Signed-off-by: Mattias Nissler <mnissler@google.com>
Change-Id: I2f2c625205358d68086c32e35b9ca814252786c4
diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 88a2c8e..5728779 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -629,12 +629,14 @@
perf_event_paranoid:
Controls use of the performance events system by unprivileged
-users (without CAP_SYS_ADMIN). The default value is 1.
+users (without CAP_SYS_ADMIN). The default value is 3 if
+CONFIG_SECURITY_PERF_EVENTS_RESTRICT is set, or 1 otherwise.
-1: Allow use of (almost) all events by all users
>=0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
>=1: Disallow CPU event access by users without CAP_SYS_ADMIN
>=2: Disallow kernel profiling by users without CAP_SYS_ADMIN
+>=3: Disallow all event access by users without CAP_SYS_ADMIN
==============================================================
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f9828a4..aa72940 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -989,6 +989,11 @@
loff_t *ppos);
+static inline bool perf_paranoid_any(void)
+{
+ return sysctl_perf_event_paranoid > 2;
+}
+
static inline bool perf_paranoid_tracepoint_raw(void)
{
return sysctl_perf_event_paranoid > -1;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1e889a0..fb9b3b5 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -175,8 +175,13 @@
* 0 - disallow raw tracepoint access for unpriv
* 1 - disallow cpu events for unpriv
* 2 - disallow kernel profiling for unpriv
+ * 3 - disallow all unpriv perf event use
*/
+#ifdef CONFIG_SECURITY_PERF_EVENTS_RESTRICT
+int sysctl_perf_event_paranoid __read_mostly = 3;
+#else
int sysctl_perf_event_paranoid __read_mostly = 1;
+#endif
/* Minimum for 512 kiB + 1 user control page */
int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
@@ -8268,6 +8273,9 @@
if (flags & ~PERF_FLAG_ALL)
return -EINVAL;
+ if (perf_paranoid_any() && !capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
err = perf_copy_attr(attr_uptr, &attr);
if (err)
return err;
diff --git a/security/Kconfig b/security/Kconfig
index e452378..30a2603 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -18,6 +18,15 @@
If you are unsure how to answer this question, answer N.
+config SECURITY_PERF_EVENTS_RESTRICT
+ bool "Restrict unprivileged use of performance events"
+ depends on PERF_EVENTS
+ help
+ If you say Y here, the kernel.perf_event_paranoid sysctl
+ will be set to 3 by default, and no unprivileged use of the
+ perf_event_open syscall will be permitted unless it is
+ changed.
+
config SECURITY
bool "Enable different security models"
depends on SYSFS
