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Add a text program, built to run on the host, to check all newly built DSOs for executable stacks and fail if the stack information is missing or indicates executable stacks.
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Ulrich Drepper
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Ulrich Drepper
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May 15, 2009
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| /* Check for executable stacks in DSOs. | ||
| Copyright (C) 2009 Free Software Foundation, Inc. | ||
| This file is part of the GNU C Library. | ||
| Contribute by Ulrich Drepper <drepper@redhat.com>. 2009. | ||
| 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 <byteswap.h> | ||
| #include <elf.h> | ||
| #include <endian.h> | ||
| #include <fcntl.h> | ||
| #include <stdio.h> | ||
| #include <stdlib.h> | ||
| #include <string.h> | ||
| #include <unistd.h> | ||
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| #ifdef BITS | ||
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| # define AB(name) _AB (name, BITS) | ||
| # define _AB(name, bits) __AB (name, bits) | ||
| # define __AB(name, bits) name##bits | ||
| # define E(name) _E (name, BITS) | ||
| # define _E(name, bits) __E (name, bits) | ||
| # define __E(name, bits) Elf##bits##_##name | ||
| # define SWAP(val) \ | ||
| ({ __typeof (val) __res; \ | ||
| if (((ehdr.e_ident[EI_DATA] == ELFDATA2MSB \ | ||
| && BYTE_ORDER == LITTLE_ENDIAN) \ | ||
| || (ehdr.e_ident[EI_DATA] == ELFDATA2LSB \ | ||
| && BYTE_ORDER == BIG_ENDIAN)) \ | ||
| && sizeof (val) != 1) \ | ||
| { \ | ||
| if (sizeof (val) == 2) \ | ||
| __res = bswap_16 (val); \ | ||
| else if (sizeof (val) == 4) \ | ||
| __res = bswap_32 (val); \ | ||
| else \ | ||
| __res = bswap_64 (val); \ | ||
| } \ | ||
| else \ | ||
| __res = (val); \ | ||
| __res; }) | ||
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| static int | ||
| AB(handle_file) (const char *fname, int fd) | ||
| { | ||
| E(Ehdr) ehdr; | ||
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| if (pread (fd, &ehdr, sizeof (ehdr), 0) != sizeof (ehdr)) | ||
| { | ||
| read_error: | ||
| printf ("%s: read error: %m\n", fname); | ||
| return 1; | ||
| } | ||
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| const size_t phnum = SWAP (ehdr.e_phnum); | ||
| const size_t phentsize = SWAP (ehdr.e_phentsize); | ||
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| /* Read the program header. */ | ||
| E(Phdr) *phdr = alloca (phentsize * phnum); | ||
| if (pread (fd, phdr, phentsize * phnum, SWAP (ehdr.e_phoff)) | ||
| != phentsize * phnum) | ||
| goto read_error; | ||
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| /* Search for the PT_GNU_STACK entry. */ | ||
| for (size_t cnt = 0; cnt < phnum; ++cnt) | ||
| if (SWAP (phdr[cnt].p_type) == PT_GNU_STACK) | ||
| { | ||
| unsigned int flags = SWAP(phdr[cnt].p_flags); | ||
| if (flags & PF_X) | ||
| { | ||
| printf ("%s: executable stack signaled\n", fname); | ||
| return 1; | ||
| } | ||
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| return 0; | ||
| } | ||
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| printf ("%s: no PT_GNU_STACK entry\n", fname); | ||
| return 1; | ||
| } | ||
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| # undef BITS | ||
| #else | ||
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| # define BITS 32 | ||
| # include "check-execstack.c" | ||
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| # define BITS 64 | ||
| # include "check-execstack.c" | ||
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| static int | ||
| handle_file (const char *fname) | ||
| { | ||
| int fd = open (fname, O_RDONLY); | ||
| if (fd == -1) | ||
| { | ||
| printf ("cannot open %s: %m\n", fname); | ||
| return 1; | ||
| } | ||
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| /* Read was is supposed to be the ELF header. Read the initial | ||
| bytes to determine whether this is a 32 or 64 bit file. */ | ||
| char ident[EI_NIDENT]; | ||
| if (read (fd, ident, EI_NIDENT) != EI_NIDENT) | ||
| { | ||
| printf ("%s: read error: %m\n", fname); | ||
| close (fd); | ||
| return 1; | ||
| } | ||
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| if (memcmp (&ident[EI_MAG0], ELFMAG, SELFMAG) != 0) | ||
| { | ||
| printf ("%s: not an ELF file\n", fname); | ||
| close (fd); | ||
| return 1; | ||
| } | ||
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| int result; | ||
| if (ident[EI_CLASS] == ELFCLASS64) | ||
| result = handle_file64 (fname, fd); | ||
| else | ||
| result = handle_file32 (fname, fd); | ||
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| close (fd); | ||
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| return result; | ||
| } | ||
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| int | ||
| main (int argc, char *argv[]) | ||
| { | ||
| int cnt; | ||
| int result = 0; | ||
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| for (cnt = 1; cnt < argc; ++cnt) | ||
| result |= handle_file (argv[cnt]); | ||
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| return result; | ||
| } | ||
| #endif |