mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 13:55:32 +00:00
![Dan Williams](/assets/img/avatar_default.png)
In reaction to a proposal to introduce a memcpy_mcsafe_fast() implementation Linus points out that memcpy_mcsafe() is poorly named relative to communicating the scope of the interface. Specifically what addresses are valid to pass as source, destination, and what faults / exceptions are handled. Of particular concern is that even though x86 might be able to handle the semantics of copy_mc_to_user() with its common copy_user_generic() implementation other archs likely need / want an explicit path for this case: On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote: > > > > However now I see that copy_user_generic() works for the wrong reason. > > It works because the exception on the source address due to poison > > looks no different than a write fault on the user address to the > > caller, it's still just a short copy. So it makes copy_to_user() work > > for the wrong reason relative to the name. > > Right. > > And it won't work that way on other architectures. On x86, we have a > generic function that can take faults on either side, and we use it > for both cases (and for the "in_user" case too), but that's an > artifact of the architecture oddity. > > In fact, it's probably wrong even on x86 - because it can hide bugs - > but writing those things is painful enough that everybody prefers > having just one function. Replace a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel(). Introduce an x86 copy_mc_fragile() name as the rename for the low-level x86 implementation formerly named memcpy_mcsafe(). It is used as the slow / careful backend that is supplanted by a fast copy_mc_generic() in a follow-on patch. One side-effect of this reorganization is that separating copy_mc_64.S to its own file means that perf no longer needs to track dependencies for its memcpy_64.S benchmarks. [ bp: Massage a bit. ] Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: <stable@vger.kernel.org> Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
538 lines
16 KiB
C
538 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_STRING_H_
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#define _LINUX_STRING_H_
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#include <linux/compiler.h> /* for inline */
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#include <linux/types.h> /* for size_t */
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#include <linux/stddef.h> /* for NULL */
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#include <stdarg.h>
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#include <uapi/linux/string.h>
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extern char *strndup_user(const char __user *, long);
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extern void *memdup_user(const void __user *, size_t);
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extern void *vmemdup_user(const void __user *, size_t);
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extern void *memdup_user_nul(const void __user *, size_t);
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/*
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* Include machine specific inline routines
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*/
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#include <asm/string.h>
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#ifndef __HAVE_ARCH_STRCPY
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extern char * strcpy(char *,const char *);
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#endif
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#ifndef __HAVE_ARCH_STRNCPY
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extern char * strncpy(char *,const char *, __kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_STRLCPY
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size_t strlcpy(char *, const char *, size_t);
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#endif
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#ifndef __HAVE_ARCH_STRSCPY
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ssize_t strscpy(char *, const char *, size_t);
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#endif
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/* Wraps calls to strscpy()/memset(), no arch specific code required */
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ssize_t strscpy_pad(char *dest, const char *src, size_t count);
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#ifndef __HAVE_ARCH_STRCAT
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extern char * strcat(char *, const char *);
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#endif
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#ifndef __HAVE_ARCH_STRNCAT
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extern char * strncat(char *, const char *, __kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_STRLCAT
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extern size_t strlcat(char *, const char *, __kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_STRCMP
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extern int strcmp(const char *,const char *);
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#endif
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#ifndef __HAVE_ARCH_STRNCMP
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extern int strncmp(const char *,const char *,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_STRCASECMP
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extern int strcasecmp(const char *s1, const char *s2);
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#endif
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#ifndef __HAVE_ARCH_STRNCASECMP
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extern int strncasecmp(const char *s1, const char *s2, size_t n);
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#endif
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#ifndef __HAVE_ARCH_STRCHR
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extern char * strchr(const char *,int);
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#endif
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#ifndef __HAVE_ARCH_STRCHRNUL
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extern char * strchrnul(const char *,int);
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#endif
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extern char * strnchrnul(const char *, size_t, int);
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#ifndef __HAVE_ARCH_STRNCHR
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extern char * strnchr(const char *, size_t, int);
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#endif
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#ifndef __HAVE_ARCH_STRRCHR
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extern char * strrchr(const char *,int);
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#endif
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extern char * __must_check skip_spaces(const char *);
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extern char *strim(char *);
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static inline __must_check char *strstrip(char *str)
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{
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return strim(str);
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}
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#ifndef __HAVE_ARCH_STRSTR
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extern char * strstr(const char *, const char *);
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#endif
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#ifndef __HAVE_ARCH_STRNSTR
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extern char * strnstr(const char *, const char *, size_t);
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#endif
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#ifndef __HAVE_ARCH_STRLEN
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extern __kernel_size_t strlen(const char *);
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#endif
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#ifndef __HAVE_ARCH_STRNLEN
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extern __kernel_size_t strnlen(const char *,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_STRPBRK
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extern char * strpbrk(const char *,const char *);
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#endif
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#ifndef __HAVE_ARCH_STRSEP
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extern char * strsep(char **,const char *);
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#endif
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#ifndef __HAVE_ARCH_STRSPN
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extern __kernel_size_t strspn(const char *,const char *);
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#endif
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#ifndef __HAVE_ARCH_STRCSPN
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extern __kernel_size_t strcspn(const char *,const char *);
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#endif
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#ifndef __HAVE_ARCH_MEMSET
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extern void * memset(void *,int,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMSET16
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extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMSET32
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extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMSET64
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extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
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#endif
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static inline void *memset_l(unsigned long *p, unsigned long v,
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__kernel_size_t n)
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{
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if (BITS_PER_LONG == 32)
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return memset32((uint32_t *)p, v, n);
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else
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return memset64((uint64_t *)p, v, n);
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}
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static inline void *memset_p(void **p, void *v, __kernel_size_t n)
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{
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if (BITS_PER_LONG == 32)
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return memset32((uint32_t *)p, (uintptr_t)v, n);
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else
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return memset64((uint64_t *)p, (uintptr_t)v, n);
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}
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extern void **__memcat_p(void **a, void **b);
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#define memcat_p(a, b) ({ \
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BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)), \
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"type mismatch in memcat_p()"); \
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(typeof(*a) *)__memcat_p((void **)(a), (void **)(b)); \
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})
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#ifndef __HAVE_ARCH_MEMCPY
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extern void * memcpy(void *,const void *,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMMOVE
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extern void * memmove(void *,const void *,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMSCAN
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extern void * memscan(void *,int,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMCMP
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extern int memcmp(const void *,const void *,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_BCMP
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extern int bcmp(const void *,const void *,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMCHR
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extern void * memchr(const void *,int,__kernel_size_t);
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#endif
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#ifndef __HAVE_ARCH_MEMCPY_FLUSHCACHE
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static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
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{
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memcpy(dst, src, cnt);
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}
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#endif
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void *memchr_inv(const void *s, int c, size_t n);
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char *strreplace(char *s, char old, char new);
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extern void kfree_const(const void *x);
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extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
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extern const char *kstrdup_const(const char *s, gfp_t gfp);
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extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
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extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
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extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp);
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extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
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extern void argv_free(char **argv);
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extern bool sysfs_streq(const char *s1, const char *s2);
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extern int kstrtobool(const char *s, bool *res);
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static inline int strtobool(const char *s, bool *res)
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{
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return kstrtobool(s, res);
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}
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int match_string(const char * const *array, size_t n, const char *string);
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int __sysfs_match_string(const char * const *array, size_t n, const char *s);
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/**
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* sysfs_match_string - matches given string in an array
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* @_a: array of strings
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* @_s: string to match with
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*
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* Helper for __sysfs_match_string(). Calculates the size of @a automatically.
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*/
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#define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s)
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#ifdef CONFIG_BINARY_PRINTF
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int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
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int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
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int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
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#endif
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extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
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const void *from, size_t available);
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int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
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/**
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* strstarts - does @str start with @prefix?
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* @str: string to examine
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* @prefix: prefix to look for.
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*/
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static inline bool strstarts(const char *str, const char *prefix)
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{
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return strncmp(str, prefix, strlen(prefix)) == 0;
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}
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size_t memweight(const void *ptr, size_t bytes);
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/**
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* memzero_explicit - Fill a region of memory (e.g. sensitive
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* keying data) with 0s.
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* @s: Pointer to the start of the area.
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* @count: The size of the area.
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*
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* Note: usually using memset() is just fine (!), but in cases
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* where clearing out _local_ data at the end of a scope is
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* necessary, memzero_explicit() should be used instead in
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* order to prevent the compiler from optimising away zeroing.
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*
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* memzero_explicit() doesn't need an arch-specific version as
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* it just invokes the one of memset() implicitly.
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*/
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static inline void memzero_explicit(void *s, size_t count)
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{
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memset(s, 0, count);
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barrier_data(s);
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}
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/**
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* kbasename - return the last part of a pathname.
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*
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* @path: path to extract the filename from.
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*/
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static inline const char *kbasename(const char *path)
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{
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const char *tail = strrchr(path, '/');
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return tail ? tail + 1 : path;
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}
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#define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline))
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#define __RENAME(x) __asm__(#x)
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void fortify_panic(const char *name) __noreturn __cold;
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void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter");
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void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter");
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void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter");
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void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter");
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#if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
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#ifdef CONFIG_KASAN
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extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
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extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
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extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
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extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
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extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
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extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
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extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
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extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
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extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
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extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
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#else
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#define __underlying_memchr __builtin_memchr
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#define __underlying_memcmp __builtin_memcmp
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#define __underlying_memcpy __builtin_memcpy
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#define __underlying_memmove __builtin_memmove
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#define __underlying_memset __builtin_memset
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#define __underlying_strcat __builtin_strcat
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#define __underlying_strcpy __builtin_strcpy
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#define __underlying_strlen __builtin_strlen
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#define __underlying_strncat __builtin_strncat
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#define __underlying_strncpy __builtin_strncpy
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#endif
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__FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__write_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __underlying_strncpy(p, q, size);
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}
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__FORTIFY_INLINE char *strcat(char *p, const char *q)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (p_size == (size_t)-1)
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return __underlying_strcat(p, q);
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if (strlcat(p, q, p_size) >= p_size)
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fortify_panic(__func__);
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return p;
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}
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__FORTIFY_INLINE __kernel_size_t strlen(const char *p)
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{
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__kernel_size_t ret;
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size_t p_size = __builtin_object_size(p, 0);
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/* Work around gcc excess stack consumption issue */
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if (p_size == (size_t)-1 ||
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(__builtin_constant_p(p[p_size - 1]) && p[p_size - 1] == '\0'))
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return __underlying_strlen(p);
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ret = strnlen(p, p_size);
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if (p_size <= ret)
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fortify_panic(__func__);
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return ret;
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}
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extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
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__FORTIFY_INLINE __kernel_size_t strnlen(const char *p, __kernel_size_t maxlen)
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{
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size_t p_size = __builtin_object_size(p, 0);
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__kernel_size_t ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
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if (p_size <= ret && maxlen != ret)
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fortify_panic(__func__);
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return ret;
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}
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/* defined after fortified strlen to reuse it */
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extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
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__FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size)
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{
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size_t ret;
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size_t p_size = __builtin_object_size(p, 0);
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size_t q_size = __builtin_object_size(q, 0);
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if (p_size == (size_t)-1 && q_size == (size_t)-1)
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return __real_strlcpy(p, q, size);
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ret = strlen(q);
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if (size) {
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size_t len = (ret >= size) ? size - 1 : ret;
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if (__builtin_constant_p(len) && len >= p_size)
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__write_overflow();
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if (len >= p_size)
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fortify_panic(__func__);
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__underlying_memcpy(p, q, len);
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p[len] = '\0';
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}
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return ret;
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}
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/* defined after fortified strlen and strnlen to reuse them */
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__FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count)
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{
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size_t p_len, copy_len;
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size_t p_size = __builtin_object_size(p, 0);
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size_t q_size = __builtin_object_size(q, 0);
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if (p_size == (size_t)-1 && q_size == (size_t)-1)
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return __underlying_strncat(p, q, count);
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p_len = strlen(p);
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copy_len = strnlen(q, count);
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if (p_size < p_len + copy_len + 1)
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fortify_panic(__func__);
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__underlying_memcpy(p + p_len, q, copy_len);
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p[p_len + copy_len] = '\0';
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return p;
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}
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__FORTIFY_INLINE void *memset(void *p, int c, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__write_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __underlying_memset(p, c, size);
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}
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__FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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size_t q_size = __builtin_object_size(q, 0);
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if (__builtin_constant_p(size)) {
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if (p_size < size)
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__write_overflow();
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if (q_size < size)
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__read_overflow2();
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}
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if (p_size < size || q_size < size)
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fortify_panic(__func__);
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return __underlying_memcpy(p, q, size);
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}
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__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
size_t q_size = __builtin_object_size(q, 0);
|
|
if (__builtin_constant_p(size)) {
|
|
if (p_size < size)
|
|
__write_overflow();
|
|
if (q_size < size)
|
|
__read_overflow2();
|
|
}
|
|
if (p_size < size || q_size < size)
|
|
fortify_panic(__func__);
|
|
return __underlying_memmove(p, q, size);
|
|
}
|
|
|
|
extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
|
|
__FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
if (__builtin_constant_p(size) && p_size < size)
|
|
__read_overflow();
|
|
if (p_size < size)
|
|
fortify_panic(__func__);
|
|
return __real_memscan(p, c, size);
|
|
}
|
|
|
|
__FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
size_t q_size = __builtin_object_size(q, 0);
|
|
if (__builtin_constant_p(size)) {
|
|
if (p_size < size)
|
|
__read_overflow();
|
|
if (q_size < size)
|
|
__read_overflow2();
|
|
}
|
|
if (p_size < size || q_size < size)
|
|
fortify_panic(__func__);
|
|
return __underlying_memcmp(p, q, size);
|
|
}
|
|
|
|
__FORTIFY_INLINE void *memchr(const void *p, int c, __kernel_size_t size)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
if (__builtin_constant_p(size) && p_size < size)
|
|
__read_overflow();
|
|
if (p_size < size)
|
|
fortify_panic(__func__);
|
|
return __underlying_memchr(p, c, size);
|
|
}
|
|
|
|
void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
|
|
__FORTIFY_INLINE void *memchr_inv(const void *p, int c, size_t size)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
if (__builtin_constant_p(size) && p_size < size)
|
|
__read_overflow();
|
|
if (p_size < size)
|
|
fortify_panic(__func__);
|
|
return __real_memchr_inv(p, c, size);
|
|
}
|
|
|
|
extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup);
|
|
__FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
if (__builtin_constant_p(size) && p_size < size)
|
|
__read_overflow();
|
|
if (p_size < size)
|
|
fortify_panic(__func__);
|
|
return __real_kmemdup(p, size, gfp);
|
|
}
|
|
|
|
/* defined after fortified strlen and memcpy to reuse them */
|
|
__FORTIFY_INLINE char *strcpy(char *p, const char *q)
|
|
{
|
|
size_t p_size = __builtin_object_size(p, 0);
|
|
size_t q_size = __builtin_object_size(q, 0);
|
|
if (p_size == (size_t)-1 && q_size == (size_t)-1)
|
|
return __underlying_strcpy(p, q);
|
|
memcpy(p, q, strlen(q) + 1);
|
|
return p;
|
|
}
|
|
|
|
/* Don't use these outside the FORITFY_SOURCE implementation */
|
|
#undef __underlying_memchr
|
|
#undef __underlying_memcmp
|
|
#undef __underlying_memcpy
|
|
#undef __underlying_memmove
|
|
#undef __underlying_memset
|
|
#undef __underlying_strcat
|
|
#undef __underlying_strcpy
|
|
#undef __underlying_strlen
|
|
#undef __underlying_strncat
|
|
#undef __underlying_strncpy
|
|
#endif
|
|
|
|
/**
|
|
* memcpy_and_pad - Copy one buffer to another with padding
|
|
* @dest: Where to copy to
|
|
* @dest_len: The destination buffer size
|
|
* @src: Where to copy from
|
|
* @count: The number of bytes to copy
|
|
* @pad: Character to use for padding if space is left in destination.
|
|
*/
|
|
static inline void memcpy_and_pad(void *dest, size_t dest_len,
|
|
const void *src, size_t count, int pad)
|
|
{
|
|
if (dest_len > count) {
|
|
memcpy(dest, src, count);
|
|
memset(dest + count, pad, dest_len - count);
|
|
} else
|
|
memcpy(dest, src, dest_len);
|
|
}
|
|
|
|
/**
|
|
* str_has_prefix - Test if a string has a given prefix
|
|
* @str: The string to test
|
|
* @prefix: The string to see if @str starts with
|
|
*
|
|
* A common way to test a prefix of a string is to do:
|
|
* strncmp(str, prefix, sizeof(prefix) - 1)
|
|
*
|
|
* But this can lead to bugs due to typos, or if prefix is a pointer
|
|
* and not a constant. Instead use str_has_prefix().
|
|
*
|
|
* Returns:
|
|
* * strlen(@prefix) if @str starts with @prefix
|
|
* * 0 if @str does not start with @prefix
|
|
*/
|
|
static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
|
|
{
|
|
size_t len = strlen(prefix);
|
|
return strncmp(str, prefix, len) == 0 ? len : 0;
|
|
}
|
|
|
|
#endif /* _LINUX_STRING_H_ */
|