Commit d597580d authored by Al Viro's avatar Al Viro
Browse files

generic ...copy_..._user primitives 



provide raw_copy_..._user() and select ARCH_HAS_RAW_COPY_USER to use those.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent c1aad8dc

arch/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -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"

include/asm-generic/uaccess.h

+11 −0
Original line number Diff line number Diff line
@@ -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.

include/linux/uaccess.h

+187 −0
Original line number Diff line number Diff line
@@ -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++;

lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -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

lib/usercopy.c

0 → 100644
+26 −0
Original line number Diff line number Diff line 
#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