Add explicit_bzero(3) and its kernel counterpart.

Obtained from:	OpenBSD
MFC after:	2 weeks
This commit is contained in:
Xin LI 2014-10-07 04:54:11 +00:00
parent 84e874bd6c
commit 78b59024b5
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=272673
8 changed files with 74 additions and 2 deletions

View File

@ -43,6 +43,9 @@ int bcmp(const void *, const void *, size_t) __pure; /* LEGACY */
void bcopy(const void *, void *, size_t); /* LEGACY */
void bzero(void *, size_t); /* LEGACY */
#endif
#if __BSD_VISIBLE
void explicit_bzero(void *, size_t);
#endif
#if __XSI_VISIBLE
int ffs(int) __pure2;
#endif

View File

@ -6,7 +6,8 @@
CFLAGS+= -I${LIBC_SRCTOP}/locale
# machine-independent string sources
MISRCS+=bcmp.c bcopy.c bzero.c ffs.c ffsl.c ffsll.c fls.c flsl.c flsll.c \
MISRCS+=bcmp.c bcopy.c bzero.c explicit_bzero.c \
ffs.c ffsl.c ffsll.c fls.c flsl.c flsll.c \
memccpy.c memchr.c memrchr.c memcmp.c \
memcpy.c memmem.c memmove.c memset.c \
stpcpy.c stpncpy.c strcasecmp.c \

View File

@ -100,6 +100,10 @@ FBSD_1.3 {
wcwidth_l;
};
FBSD_1.4 {
explicit_bzero;
};
FBSDprivate_1.0 {
__strtok_r;
};

View File

@ -35,7 +35,8 @@
.Dt BZERO 3
.Os
.Sh NAME
.Nm bzero
.Nm bzero ,
.Nm explicit_bzero
.Nd write zeroes to a byte string
.Sh LIBRARY
.Lb libc
@ -43,6 +44,8 @@
.In strings.h
.Ft void
.Fn bzero "void *b" "size_t len"
.Ft void
.Fn explicit_bzero "void *b" "size_t len"
.Sh DESCRIPTION
The
.Fn bzero
@ -56,6 +59,12 @@ If
is zero,
.Fn bzero
does nothing.
.Pp
The
.Fn explicit_bzero
variant behaves the same, but will not be removed by a compiler's dead store
optimization pass, making it useful for clearing sensitive memory such as a
password.
.Sh SEE ALSO
.Xr memset 3 ,
.Xr swab 3
@ -72,3 +81,10 @@ before it was moved to
for
.St -p1003.1-2001
compliance.
.Pp
The
.Fn explicit_bzero
function first appeared in
.Ox 5.5
and
.Fx 11.0 .

View File

@ -0,0 +1,22 @@
/* $OpenBSD: explicit_bzero.c,v 1.3 2014/06/21 02:34:26 matthew Exp $ */
/*
* Public domain.
* Written by Matthew Dempsky.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <string.h>
__attribute__((weak)) void
__explicit_bzero_hook(void *buf, size_t len)
{
}
void
explicit_bzero(void *buf, size_t len)
{
memset(buf, 0, len);
__explicit_bzero_hook(buf, len);
}

View File

@ -3163,6 +3163,7 @@ libkern/arc4random.c standard
libkern/bcd.c standard
libkern/bsearch.c standard
libkern/crc32.c standard
libkern/explicit_bzero.c standard
libkern/fnmatch.c standard
libkern/iconv.c optional libiconv
libkern/iconv_converter_if.m optional libiconv

View File

@ -0,0 +1,24 @@
/* $OpenBSD: explicit_bzero.c,v 1.3 2014/06/21 02:34:26 matthew Exp $ */
/*
* Public domain.
* Written by Matthew Dempsky.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/libkern.h>
__attribute__((weak)) void __explicit_bzero_hook(void *, size_t);
__attribute__((weak)) void
__explicit_bzero_hook(void *buf, size_t len)
{
}
void
explicit_bzero(void *buf, size_t len)
{
memset(buf, 0, len);
__explicit_bzero_hook(buf, len);
}

View File

@ -232,6 +232,7 @@ void hexdump(const void *ptr, int length, const char *hdr, int flags);
#define ovbcopy(f, t, l) bcopy((f), (t), (l))
void bcopy(const void *from, void *to, size_t len) __nonnull(1) __nonnull(2);
void bzero(void *buf, size_t len) __nonnull(1);
void explicit_bzero(void *, size_t) __nonnull(1);;
void *memcpy(void *to, const void *from, size_t len) __nonnull(1) __nonnull(2);
void *memmove(void *dest, const void *src, size_t n) __nonnull(1) __nonnull(2);