Commit 2922585b authored by David S. Miller's avatar David S. Miller
Browse files

lib: Sparc's strncpy_from_user is generic enough, move under lib/ 



To use this, an architecture simply needs to:

1) Provide a user_addr_max() implementation via asm/uaccess.h

2) Add "select GENERIC_STRNCPY_FROM_USER" to their arch Kcnfig

3) Remove the existing strncpy_from_user() implementation and symbol
   exports their architecture had.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarDavid Howells <dhowells@redhat.com>
parent 44696908

arch/sparc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ config SPARC 
	select HAVE_NMI_WATCHDOG if SPARC64

	select HAVE_BPF_JIT

	select GENERIC_SMP_IDLE_THREAD

	select GENERIC_STRNCPY_FROM_USER



config SPARC32

	def_bool !64BIT

arch/sparc/lib/usercopy.c

+0 −144
Original line number Diff line number Diff line 
#include <linux/module.h>

#include <linux/uaccess.h>

#include <linux/kernel.h>

#include <linux/errno.h>

#include <linux/bug.h>



#include <asm/byteorder.h>



void copy_from_user_overflow(void)

{

	WARN(1, "Buffer overflow detected!\n");

}

EXPORT_SYMBOL(copy_from_user_overflow);
 


static inline long find_zero(unsigned long mask)

{

	long byte = 0;



#ifdef __BIG_ENDIAN

#ifdef CONFIG_64BIT

	if (mask >> 32)

		mask >>= 32;

	else

		byte = 4;

#endif

	if (mask >> 16)

		mask >>= 16;

	else

		byte += 2;

	return (mask >> 8) ? byte : byte + 1;

#else

#ifdef CONFIG_64BIT

	if (!((unsigned int) mask)) {

		mask >>= 32;

		byte = 4;

	}

#endif

	if (!(mask & 0xffff)) {

		mask >>= 16;

		byte += 2;

	}

	return (mask & 0xff) ? byte : byte + 1;

#endif

}



#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS

#define IS_UNALIGNED(src, dst)	0

#else

#define IS_UNALIGNED(src, dst)	\

	(((long) dst | (long) src) & (sizeof(long) - 1))

#endif



/*

 * Do a strncpy, return length of string without final '\0'.

 * 'count' is the user-supplied count (return 'count' if we

 * hit it), 'max' is the address space maximum (and we return

 * -EFAULT if we hit it).

 */

static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)

{

	const unsigned long high_bits = REPEAT_BYTE(0xfe) + 1;

	const unsigned long low_bits = REPEAT_BYTE(0x7f);

	long res = 0;



	/*

	 * Truncate 'max' to the user-specified limit, so that

	 * we only have one limit we need to check in the loop

	 */

	if (max > count)

		max = count;



	if (IS_UNALIGNED(src, dst))

		goto byte_at_a_time;



	while (max >= sizeof(unsigned long)) {

		unsigned long c, v, rhs;



		/* Fall back to byte-at-a-time if we get a page fault */

		if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))

			break;

		rhs = c | low_bits;

		v = (c + high_bits) & ~rhs;

		*(unsigned long *)(dst+res) = c;

		if (v) {

			v = (c & low_bits) + low_bits;

			v = ~(v | rhs);

			return res + find_zero(v);

		}

		res += sizeof(unsigned long);

		max -= sizeof(unsigned long);

	}



byte_at_a_time:

	while (max) {

		char c;



		if (unlikely(__get_user(c,src+res)))

			return -EFAULT;

		dst[res] = c;

		if (!c)

			return res;

		res++;

		max--;

	}



	/*

	 * Uhhuh. We hit 'max'. But was that the user-specified maximum

	 * too? If so, that's ok - we got as much as the user asked for.

	 */

	if (res >= count)

		return res;



	/*

	 * Nope: we hit the address space limit, and we still had more

	 * characters the caller would have wanted. That's an EFAULT.

	 */

	return -EFAULT;

}



/**

 * strncpy_from_user: - Copy a NUL terminated string from userspace.

 * @dst:   Destination address, in kernel space.  This buffer must be at

 *         least @count bytes long.

 * @src:   Source address, in user space.

 * @count: Maximum number of bytes to copy, including the trailing NUL.

 *

 * Copies a NUL-terminated string from userspace to kernel space.

 *

 * On success, returns the length of the string (not including the trailing

 * NUL).

 *

 * If access to userspace fails, returns -EFAULT (some data may have been

 * copied).

 *

 * If @count is smaller than the length of the string, copies @count bytes

 * and returns @count.

 */

long strncpy_from_user(char *dst, const char __user *src, long count)

{

	unsigned long max_addr, src_addr;



	if (unlikely(count <= 0))

		return 0;



	max_addr = user_addr_max();

	src_addr = (unsigned long)src;

	if (likely(src_addr < max_addr)) {

		unsigned long max = max_addr - src_addr;

		return do_strncpy_from_user(dst, src, count, max);

	}

	return -EFAULT;

}

EXPORT_SYMBOL(strncpy_from_user);

lib/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -16,6 +16,9 @@ config BITREVERSE 
config RATIONAL

	boolean



config GENERIC_STRNCPY_FROM_USER

	bool



config GENERIC_FIND_FIRST_BIT

	bool

lib/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -123,6 +123,8 @@ obj-$(CONFIG_SIGNATURE) += digsig.o 


obj-$(CONFIG_CLZ_TAB) += clz_tab.o



obj-$(CONFIG_GENERIC_STRNCPY_FROM_USER) += strncpy_from_user.o



hostprogs-y	:= gen_crc32table

clean-files	:= crc32table.h

lib/strncpy_from_user.c

0 → 100644
+146 −0
Original line number Diff line number Diff line 
#include <linux/module.h>

#include <linux/uaccess.h>

#include <linux/kernel.h>

#include <linux/errno.h>



#include <asm/byteorder.h>



static inline long find_zero(unsigned long mask)

{

	long byte = 0;



#ifdef __BIG_ENDIAN

#ifdef CONFIG_64BIT

	if (mask >> 32)

		mask >>= 32;

	else

		byte = 4;

#endif

	if (mask >> 16)

		mask >>= 16;

	else

		byte += 2;

	return (mask >> 8) ? byte : byte + 1;

#else

#ifdef CONFIG_64BIT

	if (!((unsigned int) mask)) {

		mask >>= 32;

		byte = 4;

	}

#endif

	if (!(mask & 0xffff)) {

		mask >>= 16;

		byte += 2;

	}

	return (mask & 0xff) ? byte : byte + 1;

#endif

}



#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS

#define IS_UNALIGNED(src, dst)	0

#else

#define IS_UNALIGNED(src, dst)	\

	(((long) dst | (long) src) & (sizeof(long) - 1))

#endif



/*

 * Do a strncpy, return length of string without final '\0'.

 * 'count' is the user-supplied count (return 'count' if we

 * hit it), 'max' is the address space maximum (and we return

 * -EFAULT if we hit it).

 */

static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)

{

	const unsigned long high_bits = REPEAT_BYTE(0xfe) + 1;

	const unsigned long low_bits = REPEAT_BYTE(0x7f);

	long res = 0;



	/*

	 * Truncate 'max' to the user-specified limit, so that

	 * we only have one limit we need to check in the loop

	 */

	if (max > count)

		max = count;



	if (IS_UNALIGNED(src, dst))

		goto byte_at_a_time;



	while (max >= sizeof(unsigned long)) {

		unsigned long c, v, rhs;



		/* Fall back to byte-at-a-time if we get a page fault */

		if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))

			break;

		rhs = c | low_bits;

		v = (c + high_bits) & ~rhs;

		*(unsigned long *)(dst+res) = c;

		if (v) {

			v = (c & low_bits) + low_bits;

			v = ~(v | rhs);

			return res + find_zero(v);

		}

		res += sizeof(unsigned long);

		max -= sizeof(unsigned long);

	}



byte_at_a_time:

	while (max) {

		char c;



		if (unlikely(__get_user(c,src+res)))

			return -EFAULT;

		dst[res] = c;

		if (!c)

			return res;

		res++;

		max--;

	}



	/*

	 * Uhhuh. We hit 'max'. But was that the user-specified maximum

	 * too? If so, that's ok - we got as much as the user asked for.

	 */

	if (res >= count)

		return res;



	/*

	 * Nope: we hit the address space limit, and we still had more

	 * characters the caller would have wanted. That's an EFAULT.

	 */

	return -EFAULT;

}



/**

 * strncpy_from_user: - Copy a NUL terminated string from userspace.

 * @dst:   Destination address, in kernel space.  This buffer must be at

 *         least @count bytes long.

 * @src:   Source address, in user space.

 * @count: Maximum number of bytes to copy, including the trailing NUL.

 *

 * Copies a NUL-terminated string from userspace to kernel space.

 *

 * On success, returns the length of the string (not including the trailing

 * NUL).

 *

 * If access to userspace fails, returns -EFAULT (some data may have been

 * copied).

 *

 * If @count is smaller than the length of the string, copies @count bytes

 * and returns @count.

 */

long strncpy_from_user(char *dst, const char __user *src, long count)

{

	unsigned long max_addr, src_addr;



	if (unlikely(count <= 0))

		return 0;



	max_addr = user_addr_max();

	src_addr = (unsigned long)src;

	if (likely(src_addr < max_addr)) {

		unsigned long max = max_addr - src_addr;

		return do_strncpy_from_user(dst, src, count, max);

	}

	return -EFAULT;

}

EXPORT_SYMBOL(strncpy_from_user);

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