[PATCH 09/16] move adjtimex-related compat syscalls to native counterparts

From: Al Viro
Date: Wed Jun 07 2017 - 04:48:55 EST


From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Get rid of set_fs() mess and sanitize compat_{get,put}_timex(),
while we are at it.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
include/linux/compat.h | 4 ++
kernel/compat.c | 141 +++++++++++++++++----------------------------
kernel/time/posix-stubs.c | 2 +
kernel/time/posix-timers.c | 27 +++++++++
kernel/time/time.c | 24 +++++++-
5 files changed, 108 insertions(+), 90 deletions(-)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 1c5f3152cbb5..ecb8dd261d36 100644
--- a/include/linux/compat.h
+++ b/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 {
diff --git a/kernel/compat.c b/kernel/compat.c
index 23afa26f574b..97087b333543 100644
--- a/kernel/compat.c
+++ b/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,
diff --git a/kernel/time/posix-stubs.c b/kernel/time/posix-stubs.c
index 2fe2322d1243..9b1c8f71d164 100644
--- a/kernel/time/posix-stubs.c
+++ b/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
diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 922acf713cc0..d08a2fdeabf9 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -1003,6 +1003,33 @@ 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)
{
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 49c73c6ed648..400662f16c5a 100644
--- a/kernel/time/time.c
+++ b/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.
*
--
2.11.0