glibc/sysdeps
Zack Weinberg ea1bd74def New string function explicit_bzero (from OpenBSD).
explicit_bzero(s, n) is the same as memset(s, 0, n), except that the
compiler is not allowed to delete a call to explicit_bzero even if the
memory pointed to by 's' is dead after the call.  Right now, this effect
is achieved externally by having explicit_bzero be a function whose
semantics are unknown to the compiler, and internally, with a no-op
asm statement that clobbers memory.  This does mean that small
explicit_bzero operations cannot be expanded inline as small memset
operations can, but on the other hand, small memset operations do get
deleted by the compiler.  Hopefully full compiler support for
explicit_bzero will happen relatively soon.

There are two new tests: test-explicit_bzero.c verifies the
visible semantics in the same way as the existing test-bzero.c,
and tst-xbzero-opt.c verifies the not-being-optimized-out property.
The latter is conceptually based on a test written by Matthew Dempsky
for the OpenBSD regression suite.

The crypt() implementation has an immediate use for this new feature.
We avoid having to add a GLIBC_PRIVATE alias for explicit_bzero
by running all of libcrypt's calls through the fortified variant,
__explicit_bzero_chk, which is in the impl namespace anyway.  Currently
I'm not aware of anything in libc proper that needs this, but the
glue is all in place if it does become necessary.  The legacy DES
implementation wasn't bothering to clear its buffers, so I added that,
mostly for consistency's sake.

	* string/explicit_bzero.c: New routine.
	* string/test-explicit_bzero.c, string/tst-xbzero-opt.c: New tests.
	* string/Makefile (routines, strop-tests, tests): Add them.
	* string/test-memset.c: Add ifdeffage for testing explicit_bzero.
	* string/string.h [__USE_MISC]: Declare explicit_bzero.

	* debug/explicit_bzero_chk.c: New routine.
	* debug/Makefile (routines): Add it.
	* debug/tst-chk1.c: Test fortification of explicit_bzero.
	* string/bits/string3.h: Fortify explicit_bzero.

	* manual/string.texi: Document explicit_bzero.
	* NEWS: Mention addition of explicit_bzero.

	* crypt/crypt-entry.c (__crypt_r): Clear key-dependent intermediate
	data before returning, using explicit_bzero.
	* crypt/md5-crypt.c (__md5_crypt_r): Likewise.
	* crypt/sha256-crypt.c (__sha256_crypt_r): Likewise.
	* crypt/sha512-crypt.c (__sha512_crypt_r): Likewise.

	* include/string.h: Redirect internal uses of explicit_bzero
	to __explicit_bzero_chk[_internal].
	* string/Versions [GLIBC_2.25]: Add explicit_bzero.
	* debug/Versions [GLIBC_2.25]: Add __explicit_bzero_chk.
	* sysdeps/arm/nacl/libc.abilist
	* sysdeps/unix/sysv/linux/aarch64/libc.abilist
	* sysdeps/unix/sysv/linux/alpha/libc.abilist
	* sysdeps/unix/sysv/linux/arm/libc.abilist
	* sysdeps/unix/sysv/linux/hppa/libc.abilist
	* sysdeps/unix/sysv/linux/i386/libc.abilist
	* sysdeps/unix/sysv/linux/ia64/libc.abilist
	* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
	* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
	* sysdeps/unix/sysv/linux/microblaze/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
	* sysdeps/unix/sysv/linux/nios2/libc.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
	* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
	* sysdeps/unix/sysv/linux/sh/libc.abilist
	* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist
	* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist
	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist:
	Add entries for explicit_bzero and __explicit_bzero_chk.
2016-12-16 16:21:54 -05:00
..
aarch64 Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
alpha Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
arm New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
generic ld.so: Remove __libc_memalign 2016-11-30 16:23:58 +01:00
gnu Define wordsize.h macros everywhere 2016-11-04 09:37:44 -07:00
hppa Add missing hidden_def (__sigsetjmp). 2016-12-01 20:49:25 +00:00
i386 Fix x86, x86_64 fmax, fmin sNaN handling, add tests (bug 20947). 2016-12-15 23:52:18 +00:00
ia64 Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
ieee754 Make w_scalbln type-generic 2016-12-16 08:44:19 -02:00
init_array Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
m68k Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
mach Fix hurd __access_noerrno implementation. 2016-11-18 16:49:08 -02:00
microblaze Remove cached PID/TID in clone 2016-11-24 19:38:51 -02:00
mips Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
nacl Add llogb, llogbf, llogbl. 2016-12-02 01:42:49 +00:00
nios2 Remove cached PID/TID in clone 2016-11-24 19:38:51 -02:00
nptl Remove cached PID/TID in clone 2016-11-24 19:38:51 -02:00
posix hurd: fix fcntl visibility 2016-09-18 23:48:55 +02:00
powerpc Fix powerpc64/power7 memchr for large input sizes 2016-12-16 11:30:20 -02:00
pthread Installed-header hygiene (BZ#20366): time.h types. 2016-09-23 08:43:56 -04:00
s390 Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
sh Add missing hidden_def (__sigsetjmp). 2016-12-01 20:49:25 +00:00
sparc Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
tile Add missing hidden_def (__sigsetjmp). 2016-12-01 20:49:25 +00:00
unix New string function explicit_bzero (from OpenBSD). 2016-12-16 16:21:54 -05:00
wordsize-32 Define wordsize.h macros everywhere 2016-11-04 09:37:44 -07:00
wordsize-64 Define wordsize.h macros everywhere 2016-11-04 09:37:44 -07:00
x86 Refactor long double information into bits/long-double.h. 2016-12-14 18:27:56 +00:00
x86_64 Fix x86, x86_64 fmax, fmin sNaN handling, add tests (bug 20947). 2016-12-15 23:52:18 +00:00