Commit d597580d authored by Al Viro's avatar Al Viro

generic ...copy_..._user primitives

provide raw_copy_..._user() and select ARCH_HAS_RAW_COPY_USER to use those.
Signed-off-by: 's avatarAl Viro <viro@zeniv.linux.org.uk>
parent c1aad8dc
......@@ -847,4 +847,7 @@ config STRICT_MODULE_RWX
config ARCH_WANT_RELAX_ORDER
bool
config ARCH_HAS_RAW_COPY_USER
bool
source "kernel/gcov/Kconfig"
......@@ -86,7 +86,11 @@ static inline int __access_ok(unsigned long addr, unsigned long size)
static inline int __put_user_fn(size_t size, void __user *ptr, void *x)
{
#ifdef CONFIG_ARCH_HAS_RAW_COPY_USER
return unlikely(raw_copy_to_user(ptr, x, size)) ? -EFAULT : 0;
#else
return unlikely(__copy_to_user(ptr, x, size)) ? -EFAULT : 0;
#endif
}
#define __put_user_fn(sz, u, k) __put_user_fn(sz, u, k)
......@@ -147,7 +151,11 @@ extern int __put_user_bad(void) __attribute__((noreturn));
#ifndef __get_user_fn
static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
{
#ifdef CONFIG_ARCH_HAS_RAW_COPY_USER
return unlikely(raw_copy_from_user(x, ptr, size)) ? -EFAULT : 0;
#else
return unlikely(__copy_from_user(x, ptr, size)) ? -EFAULT : 0;
#endif
}
#define __get_user_fn(sz, u, k) __get_user_fn(sz, u, k)
......@@ -156,6 +164,8 @@ static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
extern int __get_user_bad(void) __attribute__((noreturn));
#ifndef CONFIG_ARCH_HAS_RAW_COPY_USER
#ifndef __copy_from_user_inatomic
#define __copy_from_user_inatomic __copy_from_user
#endif
......@@ -185,6 +195,7 @@ static inline long copy_to_user(void __user *to,
else
return n;
}
#endif
/*
* Copy a null terminated string from userspace.
......
......@@ -3,6 +3,7 @@
#include <linux/sched.h>
#include <linux/thread_info.h>
#include <linux/kasan-checks.h>
#define VERIFY_READ 0
#define VERIFY_WRITE 1
......@@ -11,6 +12,192 @@
#include <asm/uaccess.h>
#ifdef CONFIG_ARCH_HAS_RAW_COPY_USER
/*
* Architectures should provide two primitives (raw_copy_{to,from}_user())
* select ARCH_HAS_RAW_COPY_FROM_USER and get rid of their private instances
* of copy_{to,from}_user() and __copy_{to,from}_user{,_inatomic}(). Once
* all of them switch, this part of linux/uaccess.h will become unconditional.
*
* raw_copy_{to,from}_user(to, from, size) should copy up to size bytes and
* return the amount left to copy. They should assume that access_ok() has
* already been checked (and succeeded); they should *not* zero-pad anything.
* No KASAN or object size checks either - those belong here.
*
* Both of these functions should attempt to copy size bytes starting at from
* into the area starting at to. They must not fetch or store anything
* outside of those areas. Return value must be between 0 (everything
* copied successfully) and size (nothing copied).
*
* If raw_copy_{to,from}_user(to, from, size) returns N, size - N bytes starting
* at to must become equal to the bytes fetched from the corresponding area
* starting at from. All data past to + size - N must be left unmodified.
*
* If copying succeeds, the return value must be 0. If some data cannot be
* fetched, it is permitted to copy less than had been fetched; the only
* hard requirement is that not storing anything at all (i.e. returning size)
* should happen only when nothing could be copied. In other words, you don't
* have to squeeze as much as possible - it is allowed, but not necessary.
*
* For raw_copy_from_user() to always points to kernel memory and no faults
* on store should happen. Interpretation of from is affected by set_fs().
* For raw_copy_to_user() it's the other way round.
*
* Both can be inlined - it's up to architectures whether it wants to bother
* with that. They should not be used directly; they are used to implement
* the 6 functions (copy_{to,from}_user(), __copy_{to,from}_user_inatomic())
* that are used instead. Out of those, __... ones are inlined. Plain
* copy_{to,from}_user() might or might not be inlined. If you want them
* inlined, have asm/uaccess.h define INLINE_COPY_{TO,FROM}_USER.
*
* NOTE: only copy_from_user() zero-pads the destination in case of short copy.
* Neither __copy_from_user() nor __copy_from_user_inatomic() zero anything
* at all; their callers absolutely must check the return value.
*
* Biarch ones should also provide raw_copy_in_user() - similar to the above,
* but both source and destination are __user pointers (affected by set_fs()
* as usual) and both source and destination can trigger faults.
*/
static __always_inline unsigned long
__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
{
kasan_check_write(to, n);
check_object_size(to, n, false);
return raw_copy_from_user(to, from, n);
}
static __always_inline unsigned long
__copy_from_user(void *to, const void __user *from, unsigned long n)
{
might_fault();
kasan_check_write(to, n);
check_object_size(to, n, false);
return raw_copy_from_user(to, from, n);
}
/**
* __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
* @to: Destination address, in user space.
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
* Context: User context only.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
* The caller should also make sure he pins the user space address
* so that we don't result in page fault and sleep.
*/
static __always_inline unsigned long
__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
{
kasan_check_read(from, n);
check_object_size(from, n, true);
return raw_copy_to_user(to, from, n);
}
static __always_inline unsigned long
__copy_to_user(void __user *to, const void *from, unsigned long n)
{
might_fault();
kasan_check_read(from, n);
check_object_size(from, n, true);
return raw_copy_to_user(to, from, n);
}
#ifdef INLINE_COPY_FROM_USER
static inline unsigned long
_copy_from_user(void *to, const void __user *from, unsigned long n)
{
unsigned long res = n;
if (likely(access_ok(VERIFY_READ, from, n)))
res = raw_copy_from_user(to, from, n);
if (unlikely(res))
memset(to + (n - res), 0, res);
return res;
}
#else
extern unsigned long
_copy_from_user(void *, const void __user *, unsigned long);
#endif
#ifdef INLINE_COPY_TO_USER
static inline unsigned long
_copy_to_user(void __user *to, const void *from, unsigned long n)
{
if (access_ok(VERIFY_WRITE, to, n))
n = raw_copy_to_user(to, from, n);
return n;
}
#else
extern unsigned long
_copy_to_user(void __user *, const void *, unsigned long);
#endif
extern void __compiletime_error("usercopy buffer size is too small")
__bad_copy_user(void);
static inline void copy_user_overflow(int size, unsigned long count)
{
WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
}
static __always_inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long n)
{
int sz = __compiletime_object_size(to);
might_fault();
kasan_check_write(to, n);
if (likely(sz < 0 || sz >= n)) {
check_object_size(to, n, false);
n = _copy_from_user(to, from, n);
} else if (!__builtin_constant_p(n))
copy_user_overflow(sz, n);
else
__bad_copy_user();
return n;
}
static __always_inline unsigned long __must_check
copy_to_user(void __user *to, const void *from, unsigned long n)
{
int sz = __compiletime_object_size(from);
kasan_check_read(from, n);
might_fault();
if (likely(sz < 0 || sz >= n)) {
check_object_size(from, n, true);
n = _copy_to_user(to, from, n);
} else if (!__builtin_constant_p(n))
copy_user_overflow(sz, n);
else
__bad_copy_user();
return n;
}
#ifdef CONFIG_COMPAT
static __always_inline unsigned long __must_check
__copy_in_user(void __user *to, const void *from, unsigned long n)
{
might_fault();
return raw_copy_in_user(to, from, n);
}
static __always_inline unsigned long __must_check
copy_in_user(void __user *to, const void *from, unsigned long n)
{
might_fault();
if (access_ok(VERIFY_WRITE, to, n) && access_ok(VERIFY_READ, from, n))
n = raw_copy_in_user(to, from, n);
return n;
}
#endif
#endif
static __always_inline void pagefault_disabled_inc(void)
{
current->pagefault_disabled++;
......
......@@ -242,3 +242,5 @@ UBSAN_SANITIZE_ubsan.o := n
obj-$(CONFIG_SBITMAP) += sbitmap.o
obj-$(CONFIG_PARMAN) += parman.o
obj-$(CONFIG_ARCH_HAS_RAW_COPY_USER) += usercopy.o
#include <linux/uaccess.h>
/* out-of-line parts */
#ifndef INLINE_COPY_FROM_USER
unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
{
unsigned long res = n;
if (likely(access_ok(VERIFY_READ, from, n)))
res = raw_copy_from_user(to, from, n);
if (unlikely(res))
memset(to + (n - res), 0, res);
return res;
}
EXPORT_SYMBOL(_copy_from_user);
#endif
#ifndef INLINE_COPY_TO_USER
unsigned long _copy_to_user(void *to, const void __user *from, unsigned long n)
{
if (likely(access_ok(VERIFY_WRITE, to, n)))
n = raw_copy_to_user(to, from, n);
return n;
}
EXPORT_SYMBOL(_copy_to_user);
#endif
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