driver-core: Introduce DEVICE_ATTR_ADMIN_{RO,RW}

A common pattern for using plain DEVICE_ATTR() instead of
DEVICE_ATTR_RO() and DEVICE_ATTR_RW() is for attributes that want to
limit read to only root.  I.e. many users of DEVICE_ATTR() are
specifying 0400 or 0600 for permissions.

Given the expectation that CAP_SYS_ADMIN is needed to access these
sensitive attributes and an explicit helper with the _ADMIN_ identifier
for DEVICE_ATTR_ADMIN_{RO,RW}.

Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/159312906372.1850128.11611897078988158727.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/device.h b/include/linux/device.h
index 15460a5..d7c2570 100644 (file)
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -128,8 +128,12 @@ ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
                __ATTR_PREALLOC(_name, _mode, _show, _store)
 #define DEVICE_ATTR_RW(_name) \
        struct device_attribute dev_attr_##_name = __ATTR_RW(_name)
+#define DEVICE_ATTR_ADMIN_RW(_name) \
+       struct device_attribute dev_attr_##_name = __ATTR_RW_MODE(_name, 0600)
 #define DEVICE_ATTR_RO(_name) \
        struct device_attribute dev_attr_##_name = __ATTR_RO(_name)
+#define DEVICE_ATTR_ADMIN_RO(_name) \
+       struct device_attribute dev_attr_##_name = __ATTR_RO_MODE(_name, 0400)
 #define DEVICE_ATTR_WO(_name) \
        struct device_attribute dev_attr_##_name = __ATTR_WO(_name)
 #define DEVICE_ULONG_ATTR(_name, _mode, _var) \

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 86067db..34e8412 100644 (file)
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -123,6 +123,13 @@ struct attribute_group {
        .show   = _name##_show,                                         \
 }
 
+#define __ATTR_RW_MODE(_name, _mode) {                                 \
+       .attr   = { .name = __stringify(_name),                         \
+                   .mode = VERIFY_OCTAL_PERMISSIONS(_mode) },          \
+       .show   = _name##_show,                                         \
+       .store  = _name##_store,                                        \
+}
+
 #define __ATTR_WO(_name) {                                             \
        .attr   = { .name = __stringify(_name), .mode = 0200 },         \
        .store  = _name##_store,                                        \