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Subject[PATCH 2/7] compat: Add helper functions to read/write struct timeval, timespec
Date
From: "H. Peter Anvin" <hpa@zytor.com>

Add helper functions to read and write struct timeval and struct
timespec from userspace. We already had helper functions for reading
and writing struct compat_timespec; add a set of functions to do the
same with struct timeval, and add a second suite of functions which
can be sensitive to COMPAT_USE_64BIT_TIME and access either 32- or
64-bit time structures.

This also exports these helper functions to modules.

Rename the existing inlines for converting between struct
compat_timeval and native struct timespec so we can have a saner
naming convention for the exported functions.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
include/linux/compat.h | 16 +++++++++++
kernel/compat.c | 70 ++++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 78 insertions(+), 8 deletions(-)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 1be91c0..a82e452 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -87,10 +87,26 @@ typedef struct {
compat_sigset_word sig[_COMPAT_NSIG_WORDS];
} compat_sigset_t;

+/*
+ * These functions operate strictly on struct compat_time*
+ */
extern int get_compat_timespec(struct timespec *,
const struct compat_timespec __user *);
extern int put_compat_timespec(const struct timespec *,
struct compat_timespec __user *);
+extern int get_compat_timeval(struct timeval *,
+ const struct compat_timeval __user *);
+extern int put_compat_timeval(const struct timeval *,
+ struct compat_timeval __user *);
+/*
+ * These functions operate on 32- or 64-bit specs depending on
+ * COMPAT_USE_64BIT_TIME, hence the void user pointer arguments and the
+ * naming as compat_get/put_ rather than get/put_compat_.
+ */
+extern int compat_get_timespec(struct timespec *, const void __user *);
+extern int compat_put_timespec(const struct timespec *, void __user *);
+extern int compat_get_timeval(struct timeval *, const void __user *);
+extern int compat_put_timeval(const struct timeval *, void __user *);

struct compat_iovec {
compat_uptr_t iov_base;
diff --git a/kernel/compat.c b/kernel/compat.c
index f346ced..1743d67 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -31,11 +31,10 @@
#include <asm/uaccess.h>

/*
- * Note that the native side is already converted to a timespec, because
- * that's what we want anyway.
+ * Get/set struct timeval with struct timespec on the native side
*/
-static int compat_get_timeval(struct timespec *o,
- struct compat_timeval __user *i)
+static int compat_get_timeval_convert(struct timespec *o,
+ struct compat_timeval __user *i)
{
long usec;

@@ -46,8 +45,8 @@ static int compat_get_timeval(struct timespec *o,
return 0;
}

-static int compat_put_timeval(struct compat_timeval __user *o,
- struct timeval *i)
+static int compat_put_timeval_convert(struct compat_timeval __user *o,
+ struct timeval *i)
{
return (put_user(i->tv_sec, &o->tv_sec) ||
put_user(i->tv_usec, &o->tv_usec)) ? -EFAULT : 0;
@@ -117,7 +116,7 @@ asmlinkage long compat_sys_gettimeofday(struct compat_timeval __user *tv,
if (tv) {
struct timeval ktv;
do_gettimeofday(&ktv);
- if (compat_put_timeval(tv, &ktv))
+ if (compat_put_timeval_convert(tv, &ktv))
return -EFAULT;
}
if (tz) {
@@ -135,7 +134,7 @@ asmlinkage long compat_sys_settimeofday(struct compat_timeval __user *tv,
struct timezone ktz;

if (tv) {
- if (compat_get_timeval(&kts, tv))
+ if (compat_get_timeval_convert(&kts, tv))
return -EFAULT;
}
if (tz) {
@@ -146,12 +145,29 @@ asmlinkage long compat_sys_settimeofday(struct compat_timeval __user *tv,
return do_sys_settimeofday(tv ? &kts : NULL, tz ? &ktz : NULL);
}

+int get_compat_timeval(struct timeval *tv, const struct compat_timeval __user *ctv)
+{
+ return (!access_ok(VERIFY_READ, ctv, sizeof(*ctv)) ||
+ __get_user(tv->tv_sec, &ctv->tv_sec) ||
+ __get_user(tv->tv_usec, &ctv->tv_usec)) ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(get_compat_timeval);
+
+int put_compat_timeval(const struct timeval *tv, struct compat_timespec __user *ctv)
+{
+ return (!access_ok(VERIFY_WRITE, ctv, sizeof(*ctv)) ||
+ __put_user(tv->tv_sec, &ctv->tv_sec) ||
+ __put_user(tv->tv_usec, &ctv->tv_usec)) ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(put_compat_timeval);
+
int get_compat_timespec(struct timespec *ts, const struct compat_timespec __user *cts)
{
return (!access_ok(VERIFY_READ, cts, sizeof(*cts)) ||
__get_user(ts->tv_sec, &cts->tv_sec) ||
__get_user(ts->tv_nsec, &cts->tv_nsec)) ? -EFAULT : 0;
}
+EXPORT_SYMBOL_GPL(get_compat_timespec);

int put_compat_timespec(const struct timespec *ts, struct compat_timespec __user *cts)
{
@@ -161,6 +177,42 @@ int put_compat_timespec(const struct timespec *ts, struct compat_timespec __user
}
EXPORT_SYMBOL_GPL(put_compat_timespec);

+int compat_get_timeval(struct timeval *tv, const void __user *utv)
+{
+ if (COMPAT_USE_64BIT_TIME)
+ return get_user(tv, (const struct timeval __user *)utv);
+ else
+ return get_compat_timeval(tv, utv);
+}
+EXPORT_SYMBOL_GPL(compat_get_timeval);
+
+int compat_put_timeval(const struct timeval *tv, void __user *utv)
+{
+ if (COMPAT_USE_64BIT_TIME)
+ return put_user(tv, (struct timeval __user *)utv);
+ else
+ return put_compat_timeval(tv, utv);
+}
+EXPORT_SYMBOL_GPL(compat_put_timeval);
+
+int compat_get_timespec(struct timespec *ts, const void __user *uts)
+{
+ if (COMPAT_USE_64BIT_TIME)
+ return get_user(ts, (const struct timespec __user *)uts);
+ else
+ return get_compat_timespec(ts, uts);
+}
+EXPORT_SYMBOL_GPL(compat_get_timespec);
+
+int compat_put_timespec(const struct timespec *ts, void __user *uts)
+{
+ if (COMPAT_USE_64BIT_TIME)
+ return put_user(tv, (struct timeval __user *)ctv);
+ else
+ return put_compat_timespec(ts, uts);
+}
+EXPORT_SYMBOL_GPL(compat_put_timespec);
+
static long compat_nanosleep_restart(struct restart_block *restart)
{
struct compat_timespec __user *rmtp;
@@ -1162,3 +1214,5 @@ void __user *compat_alloc_user_space(unsigned long len)
return ptr;
}
EXPORT_SYMBOL_GPL(compat_alloc_user_space);
+
+/*
--
1.7.6.5


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