# # As of 2013-08-09 this patch is posted upstream here, but not checked in yet: # http://sourceware.org/ml/libc-alpha/2013-07/msg00367.html # http://sourceware.org/ml/libc-alpha/2013-08/msg00057.html # # Red Hat bug: # https://bugzilla.redhat.com/show_bug.cgi?id=990481 # # Upstream bug: # http://sourceware.org/bugzilla/show_bug.cgi?id=15754 # # 2013-07-19 Carlos O'Donell # # [BZ #15754] # * elf/Makefile (tests): Add tst-ptrguard1. # (tests-static): Add tst-ptrguard1-static. # (tst-ptrguard1-ARGS): Define. # (tst-ptrguard1-static-ARGS): Define. # * elf/tst-ptrguard1.c: New file. # * elf/tst-ptrguard1-static.c: New file. # * sysdeps/x86_64/stackguard-macros.h: Define POINTER_CHK_GUARD. # * sysdeps/i386/stackguard-macros.h: Likewise. # * sysdeps/powerpc/powerpc32/stackguard-macros.h: Likewise. # * sysdeps/powerpc/powerpc64/stackguard-macros.h: Likewise. # * sysdeps/s390/s390-32/stackguard-macros.h: Likewise. # * sysdeps/s390/s390-64/stackguard-macros.h: Likewise. # # 2013-07-19 Hector Marco # Ismael Ripoll # Carlos O'Donell # # [BZ #15754] # * sysdeps/generic/stackguard-macros.h: Define __pointer_chk_guard_local # and POINTER_CHK_GUARD. # * csu/libc-start.c [!SHARED && !THREAD_SET_POINTER_GUARD]: # Define __pointer_chk_guard_local. # (LIBC_START_MAIN) [!SHARED]: Call _dl_setup_pointer_guard. # Use THREAD_SET_POINTER_GUARD or set __pointer_chk_guard_local. # diff -urN glibc-2.17-c758a686/csu/libc-start.c glibc-2.17-c758a686/csu/libc-start.c --- glibc-2.17-c758a686/csu/libc-start.c 2013-08-09 17:40:41.662856773 -0400 +++ glibc-2.17-c758a686/csu/libc-start.c 2013-08-09 17:53:40.383236966 -0400 @@ -38,6 +38,12 @@ in thread local area. */ uintptr_t __stack_chk_guard attribute_relro; # endif +# ifndef THREAD_SET_POINTER_GUARD +/* Only exported for architectures that don't store the pointer guard + value in thread local area. */ +uintptr_t __pointer_chk_guard_local + attribute_relro attribute_hidden __attribute__ ((nocommon)); +# endif #endif #ifdef HAVE_PTR_NTHREADS @@ -184,6 +190,16 @@ # else __stack_chk_guard = stack_chk_guard; # endif + + /* Set up the pointer guard value. */ + uintptr_t pointer_chk_guard = _dl_setup_pointer_guard (_dl_random, + stack_chk_guard); +# ifdef THREAD_SET_POINTER_GUARD + THREAD_SET_POINTER_GUARD (pointer_chk_guard); +# else + __pointer_chk_guard_local = pointer_chk_guard; +# endif + #endif /* Register the destructor of the dynamic linker if there is any. */ diff -urN glibc-2.17-c758a686/elf/Makefile glibc-2.17-c758a686/elf/Makefile --- glibc-2.17-c758a686/elf/Makefile 2013-08-09 17:40:41.757856472 -0400 +++ glibc-2.17-c758a686/elf/Makefile 2013-08-09 17:53:40.383236966 -0400 @@ -121,7 +121,8 @@ tests = tst-tls1 tst-tls2 tst-tls9 tst-leaks1 \ tst-array1 tst-array2 tst-array3 tst-array4 tst-array5 tests-static = tst-tls1-static tst-tls2-static tst-stackguard1-static \ - tst-leaks1-static tst-array1-static tst-array5-static + tst-leaks1-static tst-array1-static tst-array5-static \ + tst-ptrguard1-static ifeq (yes,$(build-shared)) tests-static += tst-tls9-static tst-tls9-static-ENV = \ @@ -145,7 +146,7 @@ tst-audit1 tst-audit2 tst-audit8 tst-audit9 \ tst-stackguard1 tst-addr1 tst-thrlock \ tst-unique1 tst-unique2 tst-unique3 tst-unique4 \ - tst-initorder tst-initorder2 tst-relsort1 + tst-initorder tst-initorder2 tst-relsort1 tst-ptrguard1 # reldep9 test-srcs = tst-pathopt selinux-enabled := $(shell cat /selinux/enforce 2> /dev/null) @@ -1062,6 +1063,9 @@ tst-stackguard1-ARGS = --command "$(host-built-program-cmd) --child" tst-stackguard1-static-ARGS = --command "$(objpfx)tst-stackguard1-static --child" +tst-ptrguard1-ARGS = --command "$(host-built-program-cmd) --child" +tst-ptrguard1-static-ARGS = --command "$(objpfx)tst-ptrguard1-static --child" + $(objpfx)tst-leaks1: $(libdl) $(objpfx)tst-leaks1-mem: $(objpfx)tst-leaks1.out $(common-objpfx)malloc/mtrace $(objpfx)tst-leaks1.mtrace > $@ diff -urN glibc-2.17-c758a686/elf/tst-ptrguard1.c glibc-2.17-c758a686/elf/tst-ptrguard1.c --- glibc-2.17-c758a686/elf/tst-ptrguard1.c 1969-12-31 19:00:00.000000000 -0500 +++ glibc-2.17-c758a686/elf/tst-ptrguard1.c 2013-08-09 17:53:40.383236966 -0400 @@ -0,0 +1,202 @@ +/* Copyright (C) 2013 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + 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 + . */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef POINTER_CHK_GUARD +extern uintptr_t __pointer_chk_guard_local; +# define POINTER_CHK_GUARD __pointer_chk_guard_local +#endif + +static const char *command; +static bool child; +static uintptr_t ptr_chk_guard_copy; +static bool ptr_chk_guard_copy_set; +static int fds[2]; + +static void __attribute__ ((constructor)) +con (void) +{ + ptr_chk_guard_copy = POINTER_CHK_GUARD; + ptr_chk_guard_copy_set = true; +} + +static int +uintptr_t_cmp (const void *a, const void *b) +{ + if (*(uintptr_t *) a < *(uintptr_t *) b) + return 1; + if (*(uintptr_t *) a > *(uintptr_t *) b) + return -1; + return 0; +} + +static int +do_test (void) +{ + if (!ptr_chk_guard_copy_set) + { + puts ("constructor has not been run"); + return 1; + } + + if (ptr_chk_guard_copy != POINTER_CHK_GUARD) + { + puts ("POINTER_CHK_GUARD changed between constructor and do_test"); + return 1; + } + + if (child) + { + write (2, &ptr_chk_guard_copy, sizeof (ptr_chk_guard_copy)); + return 0; + } + + if (command == NULL) + { + puts ("missing --command or --child argument"); + return 1; + } + +#define N 16 + uintptr_t child_ptr_chk_guards[N + 1]; + child_ptr_chk_guards[N] = ptr_chk_guard_copy; + int i; + for (i = 0; i < N; ++i) + { + if (pipe (fds) < 0) + { + printf ("couldn't create pipe: %m\n"); + return 1; + } + + pid_t pid = fork (); + if (pid < 0) + { + printf ("fork failed: %m\n"); + return 1; + } + + if (!pid) + { + if (ptr_chk_guard_copy != POINTER_CHK_GUARD) + { + puts ("POINTER_CHK_GUARD changed after fork"); + exit (1); + } + + close (fds[0]); + close (2); + dup2 (fds[1], 2); + close (fds[1]); + + system (command); + exit (0); + } + + close (fds[1]); + + if (TEMP_FAILURE_RETRY (read (fds[0], &child_ptr_chk_guards[i], + sizeof (uintptr_t))) != sizeof (uintptr_t)) + { + puts ("could not read ptr_chk_guard value from child"); + return 1; + } + + close (fds[0]); + + pid_t termpid; + int status; + termpid = TEMP_FAILURE_RETRY (waitpid (pid, &status, 0)); + if (termpid == -1) + { + printf ("waitpid failed: %m\n"); + return 1; + } + else if (termpid != pid) + { + printf ("waitpid returned %ld != %ld\n", + (long int) termpid, (long int) pid); + return 1; + } + else if (!WIFEXITED (status) || WEXITSTATUS (status)) + { + puts ("child hasn't exited with exit status 0"); + return 1; + } + } + + qsort (child_ptr_chk_guards, N + 1, sizeof (uintptr_t), uintptr_t_cmp); + + /* The default pointer guard is the same as the default stack guard. + They are only set to default if dl_random is NULL. */ + uintptr_t default_guard = 0; + unsigned char *p = (unsigned char *) &default_guard; + p[sizeof (uintptr_t) - 1] = 255; + p[sizeof (uintptr_t) - 2] = '\n'; + p[0] = 0; + + /* Test if the pointer guard canaries are either randomized, + or equal to the default pointer guard canary value. + Even with randomized pointer guards it might happen + that the random number generator generates the same + values, but if that happens in more than half from + the 16 runs, something is very wrong. */ + int ndifferences = 0; + int ndefaults = 0; + for (i = 0; i < N; ++i) + { + if (child_ptr_chk_guards[i] != child_ptr_chk_guards[i+1]) + ndifferences++; + else if (child_ptr_chk_guards[i] == default_guard) + ndefaults++; + } + + printf ("differences %d defaults %d\n", ndifferences, ndefaults); + + if (ndifferences < N / 2 && ndefaults < N / 2) + { + puts ("pointer guard canaries are not randomized enough"); + puts ("nor equal to the default canary value"); + return 1; + } + + return 0; +} + +#define OPT_COMMAND 10000 +#define OPT_CHILD 10001 +#define CMDLINE_OPTIONS \ + { "command", required_argument, NULL, OPT_COMMAND }, \ + { "child", no_argument, NULL, OPT_CHILD }, +#define CMDLINE_PROCESS \ + case OPT_COMMAND: \ + command = optarg; \ + break; \ + case OPT_CHILD: \ + child = true; \ + break; +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" diff -urN glibc-2.17-c758a686/elf/tst-ptrguard1-static.c glibc-2.17-c758a686/elf/tst-ptrguard1-static.c --- glibc-2.17-c758a686/elf/tst-ptrguard1-static.c 1969-12-31 19:00:00.000000000 -0500 +++ glibc-2.17-c758a686/elf/tst-ptrguard1-static.c 2013-08-09 17:53:40.384236962 -0400 @@ -0,0 +1 @@ +#include "tst-ptrguard1.c" diff -urN glibc-2.17-c758a686/sysdeps/generic/stackguard-macros.h glibc-2.17-c758a686/sysdeps/generic/stackguard-macros.h --- glibc-2.17-c758a686/sysdeps/generic/stackguard-macros.h 2013-08-09 17:40:41.917855965 -0400 +++ glibc-2.17-c758a686/sysdeps/generic/stackguard-macros.h 2013-08-09 17:53:40.384236962 -0400 @@ -2,3 +2,6 @@ extern uintptr_t __stack_chk_guard; #define STACK_CHK_GUARD __stack_chk_guard + +extern uintptr_t __pointer_chk_guard_local; +#define POINTER_CHK_GUARD __pointer_chk_guard_local diff -urN glibc-2.17-c758a686/sysdeps/i386/stackguard-macros.h glibc-2.17-c758a686/sysdeps/i386/stackguard-macros.h --- glibc-2.17-c758a686/sysdeps/i386/stackguard-macros.h 2013-08-09 17:40:41.893856041 -0400 +++ glibc-2.17-c758a686/sysdeps/i386/stackguard-macros.h 2013-08-09 22:44:04.774298862 -0400 @@ -2,3 +2,11 @@ #define STACK_CHK_GUARD \ ({ uintptr_t x; asm ("movl %%gs:0x14, %0" : "=r" (x)); x; }) + +#define POINTER_CHK_GUARD \ + ({ \ + uintptr_t x; \ + asm ("movl %%gs:%c1, %0" : "=r" (x) \ + : "i" (offsetof (tcbhead_t, pointer_guard))); \ + x; \ + }) diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/stackguard-macros.h glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/stackguard-macros.h --- glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/stackguard-macros.h 2013-08-09 17:40:42.006855683 -0400 +++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc32/stackguard-macros.h 2013-08-09 22:24:48.778793075 -0400 @@ -2,3 +2,13 @@ #define STACK_CHK_GUARD \ ({ uintptr_t x; asm ("lwz %0,-28680(2)" : "=r" (x)); x; }) + +#define POINTER_CHK_GUARD \ + ({ \ + uintptr_t x; \ + asm ("lwz %0,%1(2)" \ + : "=r" (x) \ + : "i" (offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t)) \ + ); \ + x; \ + }) diff -urN glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/stackguard-macros.h glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/stackguard-macros.h --- glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/stackguard-macros.h 2013-08-09 17:40:41.994855721 -0400 +++ glibc-2.17-c758a686/sysdeps/powerpc/powerpc64/stackguard-macros.h 2013-08-09 22:24:47.831795865 -0400 @@ -2,3 +2,13 @@ #define STACK_CHK_GUARD \ ({ uintptr_t x; asm ("ld %0,-28688(13)" : "=r" (x)); x; }) + +#define POINTER_CHK_GUARD \ + ({ \ + uintptr_t x; \ + asm ("ld %0,%1(13)" \ + : "=r" (x) \ + : "i" (offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t)) \ + ); \ + x; \ + }) diff -urN glibc-2.17-c758a686/sysdeps/s390/s390-32/stackguard-macros.h glibc-2.17-c758a686/sysdeps/s390/s390-32/stackguard-macros.h --- glibc-2.17-c758a686/sysdeps/s390/s390-32/stackguard-macros.h 2013-08-09 17:40:42.059855515 -0400 +++ glibc-2.17-c758a686/sysdeps/s390/s390-32/stackguard-macros.h 2013-08-09 22:39:31.913120373 -0400 @@ -2,3 +2,15 @@ #define STACK_CHK_GUARD \ ({ uintptr_t x; asm ("ear %0,%%a0; l %0,0x14(%0)" : "=a" (x)); x; }) + +/* On s390/s390x there is no unique pointer guard, instead we use the + same value as the stack guard. */ +#define POINTER_CHK_GUARD \ + ({ \ + uintptr_t x; \ + asm ("ear %0,%%a0; l %0,%1(%0)" \ + : "=a" (x) \ + : "i" (offsetof (tcbhead_t, stack_guard))); \ + x; \ + }) + diff -urN glibc-2.17-c758a686/sysdeps/x86_64/stackguard-macros.h glibc-2.17-c758a686/sysdeps/x86_64/stackguard-macros.h --- glibc-2.17-c758a686/sysdeps/x86_64/stackguard-macros.h 2013-08-09 17:40:42.013855661 -0400 +++ glibc-2.17-c758a686/sysdeps/x86_64/stackguard-macros.h 2013-08-09 22:44:53.550153736 -0400 @@ -4,3 +4,11 @@ ({ uintptr_t x; \ asm ("mov %%fs:%c1, %0" : "=r" (x) \ : "i" (offsetof (tcbhead_t, stack_guard))); x; }) + +#define POINTER_CHK_GUARD \ + ({ \ + uintptr_t x; \ + asm ("mov %%fs:%c1, %0" : "=r" (x) \ + : "i" (offsetof (tcbhead_t, pointer_guard))); \ + x; \ + }) --- glibc-2.17-c758a686/sysdeps/s390/s390-64/stackguard-macros.h 2013-08-09 17:40:42.057855522 -0400 +++ glibc-2.17-c758a686/sysdeps/s390/s390-64/stackguard-macros.h 2013-08-26 15:21:27.239043425 -0400 @@ -2,3 +2,17 @@ #define STACK_CHK_GUARD \ ({ uintptr_t x; asm ("ear %0,%%a0; sllg %0,%0,32; ear %0,%%a1; lg %0,0x28(%0)" : "=a" (x)); x; }) + +/* On s390/s390x there is no unique pointer guard, instead we use the + same value as the stack guard. */ +#define POINTER_CHK_GUARD \ + ({ \ + uintptr_t x; \ + asm ("ear %0,%%a0;" \ + "sllg %0,%0,32;" \ + "ear %0,%%a1;" \ + "lg %0,%1(%0)" \ + : "=a" (x) \ + : "i" (offsetof (tcbhead_t, stack_guard))); \ + x; \ + })