[PATCH] rtc subsystem: add capability checks

Centralize CAP_SYS_XXX checks to avoid duplicate code and missing checks in
the drivers.

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/rtc/class.c

@@ -69,6 +69,7 @@ struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 	rtc->id = id;
 	rtc->ops = ops;
 	rtc->owner = owner;
+	rtc->max_user_freq = 64;
 	rtc->class_dev.dev = dev;
 	rtc->class_dev.class = rtc_class;
 	rtc->class_dev.release = rtc_device_release;

drivers/rtc/rtc-dev.c

@@ -214,6 +214,28 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 	struct rtc_wkalrm alarm;
 	void __user *uarg = (void __user *) arg;
 
+	/* check that the calles has appropriate permissions
+	 * for certain ioctls. doing this check here is useful
+	 * to avoid duplicate code in each driver.
+	 */
+	switch (cmd) {
+	case RTC_EPOCH_SET:
+	case RTC_SET_TIME:
+		if (!capable(CAP_SYS_TIME))
+			return -EACCES;
+		break;
+
+	case RTC_IRQP_SET:
+		if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE))
+			return -EACCES;
+		break;
+
+	case RTC_PIE_ON:
+		if (!capable(CAP_SYS_RESOURCE))
+			return -EACCES;
+		break;
+	}
+
 	/* avoid conflicting IRQ users */
 	if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
 		spin_lock(&rtc->irq_task_lock);
@@ -272,9 +294,6 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 		break;
 
 	case RTC_SET_TIME:
-		if (!capable(CAP_SYS_TIME))
-			return -EACCES;
-
 		if (copy_from_user(&tm, uarg, sizeof(tm)))
 			return -EFAULT;
 
@@ -290,10 +309,6 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file,
 			err = -EINVAL;
 			break;
 		}
-		if (!capable(CAP_SYS_TIME)) {
-			err = -EACCES;
-			break;
-		}
 		rtc_epoch = arg;
 		err = 0;
 #endif

drivers/rtc/rtc-sa1100.c

@@ -229,8 +229,6 @@ static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
 		spin_unlock_irq(&sa1100_rtc_lock);
 		return 0;
 	case RTC_PIE_ON:
-		if ((rtc_freq > 64) && !capable(CAP_SYS_RESOURCE))
-			return -EACCES;
 		spin_lock_irq(&sa1100_rtc_lock);
 		OSMR1 = TIMER_FREQ/rtc_freq + OSCR;
 		OIER |= OIER_E1;
@@ -242,8 +240,6 @@ static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
 	case RTC_IRQP_SET:
 		if (arg < 1 || arg > TIMER_FREQ)
 			return -EINVAL;
-		if ((arg > 64) && (!capable(CAP_SYS_RESOURCE)))
-			return -EACCES;
 		rtc_freq = arg;
 		return 0;
 	}

drivers/rtc/rtc-vr41xx.c

@@ -81,7 +81,6 @@ MODULE_LICENSE("GPL");
 
 #define RTC_FREQUENCY		32768
 #define MAX_PERIODIC_RATE	6553
-#define MAX_USER_PERIODIC_RATE	64
 
 static void __iomem *rtc1_base;
 static void __iomem *rtc2_base;
@@ -240,9 +239,6 @@ static int vr41xx_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long
 		if (arg > MAX_PERIODIC_RATE)
 			return -EINVAL;
 
-		if (arg > MAX_USER_PERIODIC_RATE && capable(CAP_SYS_RESOURCE) == 0)
-			return -EACCES;
-
 		periodic_frequency = arg;
 
 		count = RTC_FREQUENCY;
@@ -263,10 +259,6 @@ static int vr41xx_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long
 		/* Doesn't support before 1900 */
 		if (arg < 1900)
 			return -EINVAL;
-
-		if (capable(CAP_SYS_TIME) == 0)
-			return -EACCES;
-
 		epoch = arg;
 		break;
 	default:

include/linux/rtc.h

@@ -155,6 +155,7 @@ struct rtc_device
 	struct rtc_task *irq_task;
 	spinlock_t irq_task_lock;
 	int irq_freq;
+	int max_user_freq;
 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 	struct work_struct uie_task;
 	struct timer_list uie_timer;