diff options
Diffstat (limited to 'elf/check-execstack.c')
| -rw-r--r-- | elf/check-execstack.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/elf/check-execstack.c b/elf/check-execstack.c new file mode 100644 index 0000000..55cf487 --- /dev/null +++ b/elf/check-execstack.c @@ -0,0 +1,158 @@ +/* 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. */ + +#include <byteswap.h> +#include <elf.h> +#include <endian.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + + +#ifdef BITS + +# 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; }) + + +static int +AB(handle_file) (const char *fname, int fd) +{ + E(Ehdr) ehdr; + + if (pread (fd, &ehdr, sizeof (ehdr), 0) != sizeof (ehdr)) + { + read_error: + printf ("%s: read error: %m\n", fname); + return 1; + } + + const size_t phnum = SWAP (ehdr.e_phnum); + const size_t phentsize = SWAP (ehdr.e_phentsize); + + /* 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; + + /* 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; + } + + return 0; + } + + printf ("%s: no PT_GNU_STACK entry\n", fname); + return 1; +} + +# undef BITS +#else + +# define BITS 32 +# include "check-execstack.c" + +# define BITS 64 +# include "check-execstack.c" + + +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; + } + + /* 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; + } + + if (memcmp (&ident[EI_MAG0], ELFMAG, SELFMAG) != 0) + { + printf ("%s: not an ELF file\n", fname); + close (fd); + return 1; + } + + int result; + if (ident[EI_CLASS] == ELFCLASS64) + result = handle_file64 (fname, fd); + else + result = handle_file32 (fname, fd); + + close (fd); + + return result; +} + + +int +main (int argc, char *argv[]) +{ + int cnt; + int result = 0; + + for (cnt = 1; cnt < argc; ++cnt) + result |= handle_file (argv[cnt]); + + return result; +} +#endif |