diff options
Diffstat (limited to 'lib/libc/string')
| -rw-r--r-- | lib/libc/string/Makefile.inc | 4 | ||||
| -rw-r--r-- | lib/libc/string/Symbol.map | 4 | ||||
| -rw-r--r-- | lib/libc/string/bzero.3 | 20 | ||||
| -rw-r--r-- | lib/libc/string/explicit_bzero.c | 22 |
4 files changed, 47 insertions, 3 deletions
diff --git a/lib/libc/string/Makefile.inc b/lib/libc/string/Makefile.inc index 731f4fc..385837c 100644 --- a/lib/libc/string/Makefile.inc +++ b/lib/libc/string/Makefile.inc @@ -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 \ @@ -35,6 +36,7 @@ MAN+= bcmp.3 bcopy.3 bstring.3 bzero.3 ffs.3 index.3 memccpy.3 memchr.3 \ strspn.3 strstr.3 strtok.3 strxfrm.3 swab.3 wcscoll.3 wcstok.3 \ wcswidth.3 wcsxfrm.3 wmemchr.3 +MLINKS+=bzero.3 explicit_bzero.3 MLINKS+=ffs.3 ffsl.3 \ ffs.3 ffsll.3 \ ffs.3 fls.3 \ diff --git a/lib/libc/string/Symbol.map b/lib/libc/string/Symbol.map index 8e80165..5961092 100644 --- a/lib/libc/string/Symbol.map +++ b/lib/libc/string/Symbol.map @@ -100,6 +100,10 @@ FBSD_1.3 { wcwidth_l; }; +FBSD_1.4 { + explicit_bzero; +}; + FBSDprivate_1.0 { __strtok_r; }; diff --git a/lib/libc/string/bzero.3 b/lib/libc/string/bzero.3 index 029644a..5af1bcf 100644 --- a/lib/libc/string/bzero.3 +++ b/lib/libc/string/bzero.3 @@ -31,11 +31,12 @@ .\" @(#)bzero.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD$ .\" -.Dd June 4, 1993 +.Dd October 6, 2014 .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 . diff --git a/lib/libc/string/explicit_bzero.c b/lib/libc/string/explicit_bzero.c new file mode 100644 index 0000000..a7811b0 --- /dev/null +++ b/lib/libc/string/explicit_bzero.c @@ -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); +} |
