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authorOdin Ugedal <odin@ugedal.com>2020-04-03 19:55:28 +0200
committerTejun Heo <tj@kernel.org>2020-04-13 14:41:54 -0400
commiteec8fd0277e37cf447b88c6be181e81df867bcf1 (patch)
tree0110a5197275738dfd1d82cabecf277b521eac26 /security
parent772b3140669246e1ab32392c490d338e2eb7b803 (diff)
downloadlinux-eec8fd0277e37cf447b88c6be181e81df867bcf1.tar.bz2
device_cgroup: Cleanup cgroup eBPF device filter code
Original cgroup v2 eBPF code for filtering device access made it possible to compile with CONFIG_CGROUP_DEVICE=n and still use the eBPF filtering. Change commit 4b7d4d453fc4 ("device_cgroup: Export devcgroup_check_permission") reverted this, making it required to set it to y. Since the device filtering (and all the docs) for cgroup v2 is no longer a "device controller" like it was in v1, someone might compile their kernel with CONFIG_CGROUP_DEVICE=n. Then (for linux 5.5+) the eBPF filter will not be invoked, and all processes will be allowed access to all devices, no matter what the eBPF filter says. Signed-off-by: Odin Ugedal <odin@ugedal.com> Acked-by: Roman Gushchin <guro@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'security')
-rw-r--r--security/Makefile2
-rw-r--r--security/device_cgroup.c19
2 files changed, 17 insertions, 4 deletions
diff --git a/security/Makefile b/security/Makefile
index 22e73a3482bd..3baf435de541 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -30,7 +30,7 @@ obj-$(CONFIG_SECURITY_YAMA) += yama/
obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/
obj-$(CONFIG_SECURITY_SAFESETID) += safesetid/
obj-$(CONFIG_SECURITY_LOCKDOWN_LSM) += lockdown/
-obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o
+obj-$(CONFIG_CGROUPS) += device_cgroup.o
obj-$(CONFIG_BPF_LSM) += bpf/
# Object integrity file lists
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 7d0f8f7431ff..43ab0ad45c1b 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -15,6 +15,8 @@
#include <linux/rcupdate.h>
#include <linux/mutex.h>
+#ifdef CONFIG_CGROUP_DEVICE
+
static DEFINE_MUTEX(devcgroup_mutex);
enum devcg_behavior {
@@ -792,7 +794,7 @@ struct cgroup_subsys devices_cgrp_subsys = {
};
/**
- * __devcgroup_check_permission - checks if an inode operation is permitted
+ * devcgroup_legacy_check_permission - checks if an inode operation is permitted
* @dev_cgroup: the dev cgroup to be tested against
* @type: device type
* @major: device major number
@@ -801,7 +803,7 @@ struct cgroup_subsys devices_cgrp_subsys = {
*
* returns 0 on success, -EPERM case the operation is not permitted
*/
-static int __devcgroup_check_permission(short type, u32 major, u32 minor,
+static int devcgroup_legacy_check_permission(short type, u32 major, u32 minor,
short access)
{
struct dev_cgroup *dev_cgroup;
@@ -825,6 +827,10 @@ static int __devcgroup_check_permission(short type, u32 major, u32 minor,
return 0;
}
+#endif /* CONFIG_CGROUP_DEVICE */
+
+#if defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF)
+
int devcgroup_check_permission(short type, u32 major, u32 minor, short access)
{
int rc = BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access);
@@ -832,6 +838,13 @@ int devcgroup_check_permission(short type, u32 major, u32 minor, short access)
if (rc)
return -EPERM;
- return __devcgroup_check_permission(type, major, minor, access);
+ #ifdef CONFIG_CGROUP_DEVICE
+ return devcgroup_legacy_check_permission(type, major, minor, access);
+
+ #else /* CONFIG_CGROUP_DEVICE */
+ return 0;
+
+ #endif /* CONFIG_CGROUP_DEVICE */
}
EXPORT_SYMBOL(devcgroup_check_permission);
+#endif /* defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF) */