[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>

5 files changed, 24 insertions, 19 deletions

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index 413c7d54ea10..5396beec30d0 100644
--- a/drivers/rtc/class.c
+++ b/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;
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 07387c99df0d..61a58259c93f 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/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
diff --git a/drivers/rtc/rtc-sa1100.c b/drivers/rtc/rtc-sa1100.c
index a997529f8926..ab486fbc828d 100644
--- a/drivers/rtc/rtc-sa1100.c
+++ b/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;
         }
diff --git a/drivers/rtc/rtc-vr41xx.c b/drivers/rtc/rtc-vr41xx.c
index 277596c302e3..33e029207e26 100644
--- a/drivers/rtc/rtc-vr41xx.c
+++ b/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:
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 43310760fe73..c12cbc1b83c5 100644
--- a/include/linux/rtc.h
+++ b/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;