ntp: Split out timex validation from do_adjtimex

Split out the timex validation done in do_adjtimex into a separate
function. This will help simplify logic in following patches.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 27 insertions, 12 deletions

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 59e2749be0fa..457d2ba245fe 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -622,17 +622,13 @@ static inline void process_adjtimex_modes(struct timex *txc,
                 ntp_update_frequency();
 }
 
-/*
- * adjtimex mainly allows reading (and writing, if superuser) of
- * kernel time-keeping variables. used by xntpd.
+
+
+/**
+ * ntp_validate_timex - Ensures the timex is ok for use in do_adjtimex
  */
-int do_adjtimex(struct timex *txc)
+int ntp_validate_timex(struct timex *txc)
 {
-        struct timespec ts;
-        u32 time_tai, orig_tai;
-        int result;
-
-        /* Validate the data before disabling interrupts */
         if (txc->modes & ADJ_ADJTIME) {
                 /* singleshot must not be used with any other mode bits */
                 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
@@ -644,7 +640,6 @@ int do_adjtimex(struct timex *txc)
                 /* In order to modify anything, you gotta be super-user! */
                  if (txc->modes && !capable(CAP_SYS_TIME))
                         return -EPERM;
-
                 /*
                  * if the quartz is off by more than 10% then
                  * something is VERY wrong!
@@ -655,12 +650,32 @@ int do_adjtimex(struct timex *txc)
                         return -EINVAL;
         }
 
+        if ((txc->modes & ADJ_SETOFFSET) && (!capable(CAP_SYS_TIME)))
+                return -EPERM;
+
+        return 0;
+}
+
+
+/*
+ * adjtimex mainly allows reading (and writing, if superuser) of
+ * kernel time-keeping variables. used by xntpd.
+ */
+int do_adjtimex(struct timex *txc)
+{
+        struct timespec ts;
+        u32 time_tai, orig_tai;
+        int result;
+
+        /* Validate the data before disabling interrupts */
+        result = ntp_validate_timex(txc);
+        if (result)
+                return result;
+
         if (txc->modes & ADJ_SETOFFSET) {
                 struct timespec delta;
                 delta.tv_sec  = txc->time.tv_sec;
                 delta.tv_nsec = txc->time.tv_usec;
-                if (!capable(CAP_SYS_TIME))
-                        return -EPERM;
                 if (!(txc->modes & ADJ_NANO))
                         delta.tv_nsec *= 1000;
                 result = timekeeping_inject_offset(&delta);