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: David S. Miller <davem@davemloft.net> Acked-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David S. Miller
parent
446969084d
commit
2922585b93
5 changed files with 152 additions and 144 deletions
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@ -32,6 +32,7 @@ config SPARC
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select HAVE_NMI_WATCHDOG if SPARC64
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select HAVE_NMI_WATCHDOG if SPARC64
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select HAVE_BPF_JIT
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select HAVE_BPF_JIT
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select GENERIC_SMP_IDLE_THREAD
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select GENERIC_SMP_IDLE_THREAD
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select GENERIC_STRNCPY_FROM_USER
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config SPARC32
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config SPARC32
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def_bool !64BIT
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def_bool !64BIT
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@ -1,153 +1,9 @@
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#include <linux/module.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/kernel.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/bug.h>
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#include <linux/bug.h>
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#include <asm/byteorder.h>
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void copy_from_user_overflow(void)
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void copy_from_user_overflow(void)
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{
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{
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WARN(1, "Buffer overflow detected!\n");
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WARN(1, "Buffer overflow detected!\n");
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}
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}
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EXPORT_SYMBOL(copy_from_user_overflow);
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EXPORT_SYMBOL(copy_from_user_overflow);
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static inline long find_zero(unsigned long mask)
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{
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long byte = 0;
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#ifdef __BIG_ENDIAN
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#ifdef CONFIG_64BIT
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if (mask >> 32)
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mask >>= 32;
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else
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byte = 4;
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#endif
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if (mask >> 16)
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mask >>= 16;
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else
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byte += 2;
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return (mask >> 8) ? byte : byte + 1;
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#else
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#ifdef CONFIG_64BIT
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if (!((unsigned int) mask)) {
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mask >>= 32;
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byte = 4;
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}
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#endif
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if (!(mask & 0xffff)) {
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mask >>= 16;
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byte += 2;
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}
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return (mask & 0xff) ? byte : byte + 1;
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#endif
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}
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#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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#define IS_UNALIGNED(src, dst) 0
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#else
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#define IS_UNALIGNED(src, dst) \
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(((long) dst | (long) src) & (sizeof(long) - 1))
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#endif
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/*
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* Do a strncpy, return length of string without final '\0'.
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* 'count' is the user-supplied count (return 'count' if we
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* hit it), 'max' is the address space maximum (and we return
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* -EFAULT if we hit it).
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*/
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static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)
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{
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const unsigned long high_bits = REPEAT_BYTE(0xfe) + 1;
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const unsigned long low_bits = REPEAT_BYTE(0x7f);
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long res = 0;
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/*
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* Truncate 'max' to the user-specified limit, so that
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* we only have one limit we need to check in the loop
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*/
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if (max > count)
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max = count;
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if (IS_UNALIGNED(src, dst))
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goto byte_at_a_time;
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while (max >= sizeof(unsigned long)) {
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unsigned long c, v, rhs;
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/* Fall back to byte-at-a-time if we get a page fault */
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if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
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break;
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rhs = c | low_bits;
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v = (c + high_bits) & ~rhs;
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*(unsigned long *)(dst+res) = c;
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if (v) {
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v = (c & low_bits) + low_bits;
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v = ~(v | rhs);
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return res + find_zero(v);
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}
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res += sizeof(unsigned long);
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max -= sizeof(unsigned long);
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}
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byte_at_a_time:
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while (max) {
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char c;
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if (unlikely(__get_user(c,src+res)))
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return -EFAULT;
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dst[res] = c;
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if (!c)
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return res;
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res++;
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max--;
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}
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/*
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* Uhhuh. We hit 'max'. But was that the user-specified maximum
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* too? If so, that's ok - we got as much as the user asked for.
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*/
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if (res >= count)
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return res;
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/*
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* Nope: we hit the address space limit, and we still had more
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* characters the caller would have wanted. That's an EFAULT.
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*/
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return -EFAULT;
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}
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/**
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* strncpy_from_user: - Copy a NUL terminated string from userspace.
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* @dst: Destination address, in kernel space. This buffer must be at
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* least @count bytes long.
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* @src: Source address, in user space.
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* @count: Maximum number of bytes to copy, including the trailing NUL.
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*
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* Copies a NUL-terminated string from userspace to kernel space.
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*
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* On success, returns the length of the string (not including the trailing
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* NUL).
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*
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* If access to userspace fails, returns -EFAULT (some data may have been
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* copied).
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*
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* If @count is smaller than the length of the string, copies @count bytes
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* and returns @count.
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*/
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long strncpy_from_user(char *dst, const char __user *src, long count)
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{
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unsigned long max_addr, src_addr;
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if (unlikely(count <= 0))
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return 0;
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max_addr = user_addr_max();
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src_addr = (unsigned long)src;
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if (likely(src_addr < max_addr)) {
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unsigned long max = max_addr - src_addr;
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return do_strncpy_from_user(dst, src, count, max);
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}
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return -EFAULT;
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}
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EXPORT_SYMBOL(strncpy_from_user);
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@ -16,6 +16,9 @@ config BITREVERSE
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config RATIONAL
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config RATIONAL
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boolean
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boolean
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config GENERIC_STRNCPY_FROM_USER
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bool
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config GENERIC_FIND_FIRST_BIT
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config GENERIC_FIND_FIRST_BIT
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bool
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bool
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@ -123,6 +123,8 @@ obj-$(CONFIG_SIGNATURE) += digsig.o
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obj-$(CONFIG_CLZ_TAB) += clz_tab.o
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obj-$(CONFIG_CLZ_TAB) += clz_tab.o
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obj-$(CONFIG_GENERIC_STRNCPY_FROM_USER) += strncpy_from_user.o
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hostprogs-y := gen_crc32table
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hostprogs-y := gen_crc32table
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clean-files := crc32table.h
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clean-files := crc32table.h
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146
lib/strncpy_from_user.c
Normal file
146
lib/strncpy_from_user.c
Normal file
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@ -0,0 +1,146 @@
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <asm/byteorder.h>
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static inline long find_zero(unsigned long mask)
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{
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long byte = 0;
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#ifdef __BIG_ENDIAN
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#ifdef CONFIG_64BIT
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if (mask >> 32)
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mask >>= 32;
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else
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byte = 4;
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#endif
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if (mask >> 16)
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mask >>= 16;
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else
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byte += 2;
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return (mask >> 8) ? byte : byte + 1;
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#else
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#ifdef CONFIG_64BIT
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if (!((unsigned int) mask)) {
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mask >>= 32;
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byte = 4;
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}
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#endif
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if (!(mask & 0xffff)) {
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mask >>= 16;
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byte += 2;
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}
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return (mask & 0xff) ? byte : byte + 1;
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#endif
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}
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#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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#define IS_UNALIGNED(src, dst) 0
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#else
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#define IS_UNALIGNED(src, dst) \
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(((long) dst | (long) src) & (sizeof(long) - 1))
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#endif
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/*
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* Do a strncpy, return length of string without final '\0'.
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* 'count' is the user-supplied count (return 'count' if we
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* hit it), 'max' is the address space maximum (and we return
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* -EFAULT if we hit it).
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*/
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static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max)
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{
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const unsigned long high_bits = REPEAT_BYTE(0xfe) + 1;
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const unsigned long low_bits = REPEAT_BYTE(0x7f);
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long res = 0;
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/*
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* Truncate 'max' to the user-specified limit, so that
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* we only have one limit we need to check in the loop
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*/
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if (max > count)
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max = count;
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if (IS_UNALIGNED(src, dst))
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goto byte_at_a_time;
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while (max >= sizeof(unsigned long)) {
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unsigned long c, v, rhs;
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/* Fall back to byte-at-a-time if we get a page fault */
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if (unlikely(__get_user(c,(unsigned long __user *)(src+res))))
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break;
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rhs = c | low_bits;
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v = (c + high_bits) & ~rhs;
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*(unsigned long *)(dst+res) = c;
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if (v) {
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v = (c & low_bits) + low_bits;
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v = ~(v | rhs);
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return res + find_zero(v);
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}
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res += sizeof(unsigned long);
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max -= sizeof(unsigned long);
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}
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byte_at_a_time:
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while (max) {
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char c;
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if (unlikely(__get_user(c,src+res)))
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return -EFAULT;
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dst[res] = c;
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if (!c)
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return res;
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res++;
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max--;
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}
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/*
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* Uhhuh. We hit 'max'. But was that the user-specified maximum
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* too? If so, that's ok - we got as much as the user asked for.
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*/
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if (res >= count)
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return res;
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/*
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* Nope: we hit the address space limit, and we still had more
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* characters the caller would have wanted. That's an EFAULT.
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*/
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return -EFAULT;
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}
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/**
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* strncpy_from_user: - Copy a NUL terminated string from userspace.
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* @dst: Destination address, in kernel space. This buffer must be at
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* least @count bytes long.
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* @src: Source address, in user space.
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* @count: Maximum number of bytes to copy, including the trailing NUL.
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*
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* Copies a NUL-terminated string from userspace to kernel space.
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*
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* On success, returns the length of the string (not including the trailing
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* NUL).
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*
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* If access to userspace fails, returns -EFAULT (some data may have been
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* copied).
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*
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* If @count is smaller than the length of the string, copies @count bytes
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* and returns @count.
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*/
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long strncpy_from_user(char *dst, const char __user *src, long count)
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{
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unsigned long max_addr, src_addr;
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if (unlikely(count <= 0))
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return 0;
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max_addr = user_addr_max();
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src_addr = (unsigned long)src;
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if (likely(src_addr < max_addr)) {
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unsigned long max = max_addr - src_addr;
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return do_strncpy_from_user(dst, src, count, max);
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}
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return -EFAULT;
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}
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EXPORT_SYMBOL(strncpy_from_user);
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