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2003-09-23 Roland McGrath <roland@redhat.com>
* sysdeps/generic/ldsodefs.h (struct rtld_global): Add _dl_stack_flags and _dl_make_stack_executable_hook. Declare _dl_make_stack_executable. * elf/rtld.c (_rtld_global): Add initializer for _dl_stack_flags. (dl_main): Reset _dl_stack_flags according to PT_GNU_STACK phdr. Initialize _dl_make_stack_executable_hook. * elf/dl-support.c: Define those new variables. (_dl_non_dynamic_init): Scan phdrs for PT_GNU_STACK. (_dl_phdr): Fix type. * elf/dl-load.c (_dl_map_object_from_fd): Grok PT_GNU_STACK phdr and enable execute permission for the stack if necessary. * sysdeps/generic/dl-execstack.c: New file. * elf/Makefile (dl-routines): Add it. * elf/Versions (ld: GLIBC_PRIVATE): Add _dl_make_stack_executable. * sysdeps/unix/sysv/linux/dl-execstack.c: New file.
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/* Stack executability handling for GNU dynamic linker. Stub version. | ||
Copyright (C) 2003 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, write to the Free | ||
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | ||
02111-1307 USA. */ | ||
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#include <ldsodefs.h> | ||
#include <errno.h> | ||
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/* There is no portable way to know the bounds of the initial thread's stack | ||
so as to mprotect it. */ | ||
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int | ||
internal_function | ||
_dl_make_stack_executable (void) | ||
{ | ||
return ENOSYS; | ||
} | ||
rtld_hidden_def (_dl_make_stack_executable) |
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/* Stack executability handling for GNU dynamic linker. Linux version. | ||
Copyright (C) 2003 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, write to the Free | ||
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | ||
02111-1307 USA. */ | ||
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#include <ldsodefs.h> | ||
#include <sys/mman.h> | ||
#include <errno.h> | ||
#include <stdbool.h> | ||
#include <stackinfo.h> | ||
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extern void *__libc_stack_end; | ||
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int | ||
internal_function | ||
_dl_make_stack_executable (void) | ||
{ | ||
if (__libc_stack_end == 0) | ||
/* XXX for a DT_NEEDED library that requires the change, | ||
this is not initialized yet! | ||
*/ | ||
return ENOSYS; | ||
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#if _STACK_GROWS_DOWN | ||
/* This gives us the highest page that needs to be changed. */ | ||
uintptr_t page = (uintptr_t) __libc_stack_end & -(intptr_t) GL(dl_pagesize); | ||
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/* There is always a hole in the address space below the bottom of the | ||
stack. So when we make an mprotect call that starts below the bottom | ||
of the stack, it will include the hole and fail with ENOMEM. | ||
We start with a random guess at how deep the stack might have gotten | ||
so as to have extended the GROWSDOWN mapping to lower pages. */ | ||
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size_t size = GL(dl_pagesize) * 8; | ||
page = page + GL(dl_pagesize) - size; | ||
while (1) | ||
{ | ||
if (__mprotect ((void *) page, size, | ||
PROT_READ|PROT_WRITE|PROT_EXEC) == 0) | ||
/* We got this chunk changed; loop to do another chunk below. */ | ||
page -= size; | ||
else | ||
{ | ||
if (errno != ENOMEM) /* Unexpected failure mode. */ | ||
return errno; | ||
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if (size == GL(dl_pagesize)) | ||
/* We just tried to mprotect the top hole page and failed. | ||
We are done. */ | ||
break; | ||
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/* Our mprotect call failed because it started below the lowest | ||
stack page. Try again on just the top half of that region. */ | ||
size /= 2; | ||
page += size; | ||
} | ||
} | ||
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#elif _STACK_GROWS_UP | ||
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/* This gives us the lowest page that needs to be changed. */ | ||
uintptr_t page = (uintptr_t) __libc_stack_end & -(intptr_t) GL(dl_pagesize); | ||
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/* There is always a hole in the address space above the top of the | ||
stack. So when we make an mprotect call that spans past the top | ||
of the stack, it will include the hole and fail with ENOMEM. | ||
We start with a random guess at how deep the stack might have gotten | ||
so as to have extended the GROWSUP mapping to higher pages. */ | ||
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size_t size = GL(dl_pagesize) * 8; | ||
while (1) | ||
{ | ||
if (__mprotect ((void *) page, size, | ||
PROT_READ|PROT_WRITE|PROT_EXEC) == 0) | ||
/* We got this chunk changed; loop to do another chunk below. */ | ||
page += size; | ||
else | ||
{ | ||
if (errno != ENOMEM) /* Unexpected failure mode. */ | ||
return errno; | ||
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if (size == GL(dl_pagesize)) | ||
/* We just tried to mprotect the lowest hole page and failed. | ||
We are done. */ | ||
break; | ||
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/* Our mprotect call failed because it extended past the highest | ||
stack page. Try again on just the bottom half of that region. */ | ||
size /= 2; | ||
} | ||
} | ||
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#else | ||
# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP" | ||
#endif | ||
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return 0; | ||
} | ||
rtld_hidden_def (_dl_make_stack_executable) |