[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>

1 files changed, 22 insertions, 7 deletions

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