diff options
49 files changed, 711 insertions, 22 deletions
@@ -1,3 +1,62 @@ +2016-12-16 Zack Weinberg <zackw@panix.com> + Florian Weimer <fweimer@redhat.com> + Nick Mathewson <nickm@torproject.org> + + * 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 Joseph Myers <joseph@codesourcery.com> * math/fenv.h @@ -84,6 +84,12 @@ Version 2.25 * The functions strfromd, strfromf, and strfroml, from ISO/IEC TS 18661-1:2014, are added to libc. They convert a floating-point number into string. +* The function explicit_bzero, from OpenBSD, has been added to libc. It is + intended to be used instead of memset() to erase sensitive data after use; + the compiler will not optimize out calls to explicit_bzero even if they + are "unnecessary" (in the sense that no _correct_ program can observe the + effects of the memory clear). + * On ColdFire, MicroBlaze, Nios II and SH3, the float_t type is now defined to float instead of double. This does not affect the ABI of any libraries that are part of the GNU C Library, but may affect the ABI of other diff --git a/crypt/crypt-entry.c b/crypt/crypt-entry.c index a7dfccaa36..23e776fb9e 100644 --- a/crypt/crypt-entry.c +++ b/crypt/crypt-entry.c @@ -141,6 +141,15 @@ __crypt_r (const char *key, const char *salt, * And convert back to 6 bit ASCII */ _ufc_output_conversion_r (res[0], res[1], salt, data); + + /* + * Erase key-dependent intermediate data. Data dependent only on + * the salt is not considered sensitive. + */ + explicit_bzero (ktab, sizeof (ktab)); + explicit_bzero (data->keysched, sizeof (data->keysched)); + explicit_bzero (res, sizeof (res)); + return data->crypt_3_buf; } weak_alias (__crypt_r, crypt_r) diff --git a/crypt/md5-crypt.c b/crypt/md5-crypt.c index 2243bc7aed..6125c7f7f2 100644 --- a/crypt/md5-crypt.c +++ b/crypt/md5-crypt.c @@ -288,13 +288,13 @@ __md5_crypt_r (const char *key, const char *salt, char *buffer, int buflen) #ifndef USE_NSS __md5_init_ctx (&ctx); __md5_finish_ctx (&ctx, alt_result); - memset (&ctx, '\0', sizeof (ctx)); - memset (&alt_ctx, '\0', sizeof (alt_ctx)); + explicit_bzero (&ctx, sizeof (ctx)); + explicit_bzero (&alt_ctx, sizeof (alt_ctx)); #endif if (copied_key != NULL) - memset (copied_key, '\0', key_len); + explicit_bzero (copied_key, key_len); if (copied_salt != NULL) - memset (copied_salt, '\0', salt_len); + explicit_bzero (copied_salt, salt_len); free (free_key); return buffer; diff --git a/crypt/sha256-crypt.c b/crypt/sha256-crypt.c index d768234879..8c670ea405 100644 --- a/crypt/sha256-crypt.c +++ b/crypt/sha256-crypt.c @@ -371,16 +371,16 @@ __sha256_crypt_r (const char *key, const char *salt, char *buffer, int buflen) #ifndef USE_NSS __sha256_init_ctx (&ctx); __sha256_finish_ctx (&ctx, alt_result); - memset (&ctx, '\0', sizeof (ctx)); - memset (&alt_ctx, '\0', sizeof (alt_ctx)); + explicit_bzero (&ctx, sizeof (ctx)); + explicit_bzero (&alt_ctx, sizeof (alt_ctx)); #endif - memset (temp_result, '\0', sizeof (temp_result)); - memset (p_bytes, '\0', key_len); - memset (s_bytes, '\0', salt_len); + explicit_bzero (temp_result, sizeof (temp_result)); + explicit_bzero (p_bytes, key_len); + explicit_bzero (s_bytes, salt_len); if (copied_key != NULL) - memset (copied_key, '\0', key_len); + explicit_bzero (copied_key, key_len); if (copied_salt != NULL) - memset (copied_salt, '\0', salt_len); + explicit_bzero (copied_salt, salt_len); free (free_key); free (free_pbytes); diff --git a/crypt/sha512-crypt.c b/crypt/sha512-crypt.c index f404c88b20..dac145b2e9 100644 --- a/crypt/sha512-crypt.c +++ b/crypt/sha512-crypt.c @@ -393,16 +393,16 @@ __sha512_crypt_r (const char *key, const char *salt, char *buffer, int buflen) #ifndef USE_NSS __sha512_init_ctx (&ctx); __sha512_finish_ctx (&ctx, alt_result); - memset (&ctx, '\0', sizeof (ctx)); - memset (&alt_ctx, '\0', sizeof (alt_ctx)); + explicit_bzero (&ctx, sizeof (ctx)); + explicit_bzero (&alt_ctx, sizeof (alt_ctx)); #endif - memset (temp_result, '\0', sizeof (temp_result)); - memset (p_bytes, '\0', key_len); - memset (s_bytes, '\0', salt_len); + explicit_bzero (temp_result, sizeof (temp_result)); + explicit_bzero (p_bytes, key_len); + explicit_bzero (s_bytes, salt_len); if (copied_key != NULL) - memset (copied_key, '\0', key_len); + explicit_bzero (copied_key, key_len); if (copied_salt != NULL) - memset (copied_salt, '\0', salt_len); + explicit_bzero (copied_salt, salt_len); free (free_key); free (free_pbytes); diff --git a/debug/Makefile b/debug/Makefile index 6b5f31e4f6..84d3f92c0d 100644 --- a/debug/Makefile +++ b/debug/Makefile @@ -48,6 +48,7 @@ routines = backtrace backtracesyms backtracesymsfd noophooks \ vdprintf_chk obprintf_chk \ longjmp_chk ____longjmp_chk \ fdelt_chk poll_chk ppoll_chk \ + explicit_bzero_chk \ stack_chk_fail fortify_fail \ $(static-only-routines) static-only-routines := warning-nop stack_chk_fail_local diff --git a/debug/Versions b/debug/Versions index 0482c85f19..a6628db356 100644 --- a/debug/Versions +++ b/debug/Versions @@ -55,6 +55,9 @@ libc { GLIBC_2.16 { __poll_chk; __ppoll_chk; } + GLIBC_2.25 { + __explicit_bzero_chk; + } GLIBC_PRIVATE { __fortify_fail; } diff --git a/debug/explicit_bzero_chk.c b/debug/explicit_bzero_chk.c new file mode 100644 index 0000000000..2e507f8297 --- /dev/null +++ b/debug/explicit_bzero_chk.c @@ -0,0 +1,44 @@ +/* Generic implementation of __explicit_bzero_chk. + Copyright (C) 1991-2016 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Torbjorn Granlund (tege@sics.se). + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +/* This is the generic definition of __explicit_bzero_chk. The + __explicit_bzero_chk symbol is used as the implementation of + explicit_bzero throughout glibc. If this file is overriden by an + architecture, both __explicit_bzero_chk and + __explicit_bzero_chk_internal have to be defined (the latter not as + an IFUNC). */ + +#include <string.h> + +void +__explicit_bzero_chk (void *dst, size_t len, size_t dstlen) +{ + /* Inline __memset_chk to avoid a PLT reference to __memset_chk. */ + if (__glibc_unlikely (dstlen < len)) + __chk_fail (); + memset (dst, '\0', len); + /* Compiler barrier. */ + asm volatile ("" ::: "memory"); +} + +/* libc-internal references use the hidden + __explicit_bzero_chk_internal symbol. This is necessary if + __explicit_bzero_chk is implemented as an IFUNC because some + targets do not support hidden references to IFUNC symbols. */ +strong_alias (__explicit_bzero_chk, __explicit_bzero_chk_internal) diff --git a/debug/tst-chk1.c b/debug/tst-chk1.c index 478c2fbb81..e87a279fb2 100644 --- a/debug/tst-chk1.c +++ b/debug/tst-chk1.c @@ -160,6 +160,10 @@ do_test (void) if (memcmp (buf, "aabcdabc\0\0", 10)) FAIL (); + explicit_bzero (buf + 6, 4); + if (memcmp (buf, "aabcda\0\0\0\0", 10)) + FAIL (); + strcpy (buf + 4, "EDCBA"); if (memcmp (buf, "aabcEDCBA", 10)) FAIL (); @@ -201,6 +205,10 @@ do_test (void) if (memcmp (buf, "aabcdabc\0\0", 10)) FAIL (); + explicit_bzero (buf + 6, l0 + 4); + if (memcmp (buf, "aabcda\0\0\0\0", 10)) + |