ntp: Move adjtimex related compat syscalls to native counterparts

Get rid of set_fs() mess and sanitize compat_{get,put}_timex(),
while we are at it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170607084241.28657-9-viro@ZenIV.linux.org.uk

include/linux/compat.h

@@ -128,6 +128,10 @@ struct compat_timex {
 	compat_int_t:32; compat_int_t:32; compat_int_t:32;
 };
 
+struct timex;
+int compat_get_timex(struct timex *, const struct compat_timex __user *);
+int compat_put_timex(struct compat_timex __user *, const struct timex *);
+
 #define _COMPAT_NSIG_WORDS	(_COMPAT_NSIG / _COMPAT_NSIG_BPW)
 
 typedef struct {

kernel/compat.c

@@ -30,60 +30,64 @@
 
 #include <linux/uaccess.h>
 
-static int compat_get_timex(struct timex *txc, struct compat_timex __user *utp)
+int compat_get_timex(struct timex *txc, const struct compat_timex __user *utp)
 {
-	memset(txc, 0, sizeof(struct timex));
-
-	if (!access_ok(VERIFY_READ, utp, sizeof(struct compat_timex)) ||
-			__get_user(txc->modes, &utp->modes) ||
-			__get_user(txc->offset, &utp->offset) ||
-			__get_user(txc->freq, &utp->freq) ||
-			__get_user(txc->maxerror, &utp->maxerror) ||
-			__get_user(txc->esterror, &utp->esterror) ||
-			__get_user(txc->status, &utp->status) ||
-			__get_user(txc->constant, &utp->constant) ||
-			__get_user(txc->precision, &utp->precision) ||
-			__get_user(txc->tolerance, &utp->tolerance) ||
-			__get_user(txc->time.tv_sec, &utp->time.tv_sec) ||
-			__get_user(txc->time.tv_usec, &utp->time.tv_usec) ||
-			__get_user(txc->tick, &utp->tick) ||
-			__get_user(txc->ppsfreq, &utp->ppsfreq) ||
-			__get_user(txc->jitter, &utp->jitter) ||
-			__get_user(txc->shift, &utp->shift) ||
-			__get_user(txc->stabil, &utp->stabil) ||
-			__get_user(txc->jitcnt, &utp->jitcnt) ||
-			__get_user(txc->calcnt, &utp->calcnt) ||
-			__get_user(txc->errcnt, &utp->errcnt) ||
-			__get_user(txc->stbcnt, &utp->stbcnt))
+	struct compat_timex tx32;
+
+	if (copy_from_user(&tx32, utp, sizeof(struct compat_timex)))
 		return -EFAULT;
 
+	txc->modes = tx32.modes;
+	txc->offset = tx32.offset;
+	txc->freq = tx32.freq;
+	txc->maxerror = tx32.maxerror;
+	txc->esterror = tx32.esterror;
+	txc->status = tx32.status;
+	txc->constant = tx32.constant;
+	txc->precision = tx32.precision;
+	txc->tolerance = tx32.tolerance;
+	txc->time.tv_sec = tx32.time.tv_sec;
+	txc->time.tv_usec = tx32.time.tv_usec;
+	txc->tick = tx32.tick;
+	txc->ppsfreq = tx32.ppsfreq;
+	txc->jitter = tx32.jitter;
+	txc->shift = tx32.shift;
+	txc->stabil = tx32.stabil;
+	txc->jitcnt = tx32.jitcnt;
+	txc->calcnt = tx32.calcnt;
+	txc->errcnt = tx32.errcnt;
+	txc->stbcnt = tx32.stbcnt;
+
 	return 0;
 }
 
-static int compat_put_timex(struct compat_timex __user *utp, struct timex *txc)
-{
-	if (!access_ok(VERIFY_WRITE, utp, sizeof(struct compat_timex)) ||
-			__put_user(txc->modes, &utp->modes) ||
-			__put_user(txc->offset, &utp->offset) ||
-			__put_user(txc->freq, &utp->freq) ||
-			__put_user(txc->maxerror, &utp->maxerror) ||
-			__put_user(txc->esterror, &utp->esterror) ||
-			__put_user(txc->status, &utp->status) ||
-			__put_user(txc->constant, &utp->constant) ||
-			__put_user(txc->precision, &utp->precision) ||
-			__put_user(txc->tolerance, &utp->tolerance) ||
-			__put_user(txc->time.tv_sec, &utp->time.tv_sec) ||
-			__put_user(txc->time.tv_usec, &utp->time.tv_usec) ||
-			__put_user(txc->tick, &utp->tick) ||
-			__put_user(txc->ppsfreq, &utp->ppsfreq) ||
-			__put_user(txc->jitter, &utp->jitter) ||
-			__put_user(txc->shift, &utp->shift) ||
-			__put_user(txc->stabil, &utp->stabil) ||
-			__put_user(txc->jitcnt, &utp->jitcnt) ||
-			__put_user(txc->calcnt, &utp->calcnt) ||
-			__put_user(txc->errcnt, &utp->errcnt) ||
-			__put_user(txc->stbcnt, &utp->stbcnt) ||
-			__put_user(txc->tai, &utp->tai))
+int compat_put_timex(struct compat_timex __user *utp, const struct timex *txc)
+{
+	struct compat_timex tx32;
+
+	memset(&tx32, 0, sizeof(struct compat_timex));
+	tx32.modes = txc->modes;
+	tx32.offset = txc->offset;
+	tx32.freq = txc->freq;
+	tx32.maxerror = txc->maxerror;
+	tx32.esterror = txc->esterror;
+	tx32.status = txc->status;
+	tx32.constant = txc->constant;
+	tx32.precision = txc->precision;
+	tx32.tolerance = txc->tolerance;
+	tx32.time.tv_sec = txc->time.tv_sec;
+	tx32.time.tv_usec = txc->time.tv_usec;
+	tx32.tick = txc->tick;
+	tx32.ppsfreq = txc->ppsfreq;
+	tx32.jitter = txc->jitter;
+	tx32.shift = txc->shift;
+	tx32.stabil = txc->stabil;
+	tx32.jitcnt = txc->jitcnt;
+	tx32.calcnt = txc->calcnt;
+	tx32.errcnt = txc->errcnt;
+	tx32.stbcnt = txc->stbcnt;
+	tx32.tai = txc->tai;
+	if (copy_to_user(utp, &tx32, sizeof(struct compat_timex)))
 		return -EFAULT;
 	return 0;
 }
@@ -705,29 +709,6 @@ COMPAT_SYSCALL_DEFINE2(clock_gettime, clockid_t, which_clock,
 	return err;
 }
 
-COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
-		       struct compat_timex __user *, utp)
-{
-	struct timex txc;
-	mm_segment_t oldfs;
-	int err, ret;
-
-	err = compat_get_timex(&txc, utp);
-	if (err)
-		return err;
-
-	oldfs = get_fs();
-	set_fs(KERNEL_DS);
-	ret = sys_clock_adjtime(which_clock, (struct timex __user *) &txc);
-	set_fs(oldfs);
-
-	err = compat_put_timex(utp, &txc);
-	if (err)
-		return err;
-
-	return ret;
-}
-
 COMPAT_SYSCALL_DEFINE2(clock_getres, clockid_t, which_clock,
 		       struct compat_timespec __user *, tp)
 {
@@ -944,24 +925,6 @@ COMPAT_SYSCALL_DEFINE1(stime, compat_time_t __user *, tptr)
 
 #endif /* __ARCH_WANT_COMPAT_SYS_TIME */
 
-COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp)
-{
-	struct timex txc;
-	int err, ret;
-
-	err = compat_get_timex(&txc, utp);
-	if (err)
-		return err;
-
-	ret = do_adjtimex(&txc);
-
-	err = compat_put_timex(utp, &txc);
-	if (err)
-		return err;
-
-	return ret;
-}
-
 #ifdef CONFIG_NUMA
 COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages,
 		       compat_uptr_t __user *, pages32,

kernel/time/posix-stubs.c

@@ -28,6 +28,7 @@ asmlinkage long sys_ni_posix_timers(void)
 }
 
 #define SYS_NI(name)  SYSCALL_ALIAS(sys_##name, sys_ni_posix_timers)
+#define COMPAT_SYS_NI(name)  SYSCALL_ALIAS(compat_sys_##name, sys_ni_posix_timers)
 
 SYS_NI(timer_create);
 SYS_NI(timer_gettime);
@@ -40,6 +41,7 @@ SYS_NI(setitimer);
 #ifdef __ARCH_WANT_SYS_ALARM
 SYS_NI(alarm);
 #endif
+COMPAT_SYS_NI(clock_adjtime);
 
 /*
  * We preserve minimal support for CLOCK_REALTIME and CLOCK_MONOTONIC

kernel/time/posix-timers.c

@@ -1018,6 +1018,33 @@ SYSCALL_DEFINE2(clock_adjtime, const clockid_t, which_clock,
 	return err;
 }
 
+#ifdef CONFIG_COMPAT
+
+COMPAT_SYSCALL_DEFINE2(clock_adjtime, clockid_t, which_clock,
+		       struct compat_timex __user *, utp)
+{
+	const struct k_clock *kc = clockid_to_kclock(which_clock);
+	struct timex ktx;
+	int err;
+
+	if (!kc)
+		return -EINVAL;
+	if (!kc->clock_adj)
+		return -EOPNOTSUPP;
+
+	err = compat_get_timex(&ktx, utp);
+	if (err)
+		return err;
+
+	err = kc->clock_adj(which_clock, &ktx);
+
+	if (err >= 0)
+		err = compat_put_timex(utp, &ktx);
+
+	return err;
+}
+#endif
+
 SYSCALL_DEFINE2(clock_getres, const clockid_t, which_clock,
 		struct timespec __user *, tp)
 {

kernel/time/time.c

@@ -39,6 +39,7 @@
 #include <linux/ptrace.h>
 
 #include <linux/uaccess.h>
+#include <linux/compat.h>
 #include <asm/unistd.h>
 
 #include <generated/timeconst.h>
@@ -224,12 +225,33 @@ SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
 	 * structure. But bear in mind that the structures
 	 * may change
 	 */
-	if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
+	if (copy_from_user(&txc, txc_p, sizeof(struct timex)))
 		return -EFAULT;
 	ret = do_adjtimex(&txc);
 	return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
 }
 
+#ifdef CONFIG_COMPAT
+
+COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp)
+{
+	struct timex txc;
+	int err, ret;
+
+	err = compat_get_timex(&txc, utp);
+	if (err)
+		return err;
+
+	ret = do_adjtimex(&txc);
+
+	err = compat_put_timex(utp, &txc);
+	if (err)
+		return err;
+
+	return ret;
+}
+#endif
+
 /*
  * Convert jiffies to milliseconds and back.
  *