Author: delphij
Date: Tue Oct 7 04:54:11 2014
New Revision: 272673
URL: https://svnweb.freebsd.org/changeset/base/272673
Log:
Add explicit_bzero(3) and its kernel counterpart.
Obtained from: OpenBSD
MFC after: 2 weeks
Added:
head/lib/libc/string/explicit_bzero.c (contents, props changed)
head/sys/libkern/explicit_bzero.c (contents, props changed)
Modified:
head/include/strings.h
head/lib/libc/string/Makefile.inc
head/lib/libc/string/Symbol.map
head/lib/libc/string/bzero.3
head/sys/conf/files
head/sys/sys/systm.h
Modified: head/include/strings.h
==============================================================================
--- head/include/strings.h Mon Oct 6 23:17:01 2014 (r272672)
+++ head/include/strings.h Tue Oct 7 04:54:11 2014 (r272673)
@@ -43,6 +43,9 @@ int bcmp(const void *, const void *, si
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
Modified: head/lib/libc/string/Makefile.inc
==============================================================================
--- head/lib/libc/string/Makefile.inc Mon Oct 6 23:17:01 2014
(r272672)
+++ head/lib/libc/string/Makefile.inc Tue Oct 7 04:54:11 2014
(r272673)
@@ -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 \
Modified: head/lib/libc/string/Symbol.map
==============================================================================
--- head/lib/libc/string/Symbol.map Mon Oct 6 23:17:01 2014
(r272672)
+++ head/lib/libc/string/Symbol.map Tue Oct 7 04:54:11 2014
(r272673)
@@ -100,6 +100,10 @@ FBSD_1.3 {
wcwidth_l;
};
+FBSD_1.4 {
+ explicit_bzero;
+};
+
FBSDprivate_1.0 {
__strtok_r;
};
Modified: head/lib/libc/string/bzero.3
==============================================================================
--- head/lib/libc/string/bzero.3 Mon Oct 6 23:17:01 2014
(r272672)
+++ head/lib/libc/string/bzero.3 Tue Oct 7 04:54:11 2014
(r272673)
@@ -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 .
Added: head/lib/libc/string/explicit_bzero.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/lib/libc/string/explicit_bzero.c Tue Oct 7 04:54:11 2014
(r272673)
@@ -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);
+}
Modified: head/sys/conf/files
==============================================================================
--- head/sys/conf/files Mon Oct 6 23:17:01 2014 (r272672)
+++ head/sys/conf/files Tue Oct 7 04:54:11 2014 (r272673)
@@ -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
Added: head/sys/libkern/explicit_bzero.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/libkern/explicit_bzero.c Tue Oct 7 04:54:11 2014
(r272673)
@@ -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);
+}
Modified: head/sys/sys/systm.h
==============================================================================
--- head/sys/sys/systm.h Mon Oct 6 23:17:01 2014 (r272672)
+++ head/sys/sys/systm.h Tue Oct 7 04:54:11 2014 (r272673)
@@ -232,6 +232,7 @@ void hexdump(const void *ptr, int length
#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);
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