diff options
Diffstat (limited to 'elf/check-localplt.c')
| -rw-r--r-- | elf/check-localplt.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/elf/check-localplt.c b/elf/check-localplt.c new file mode 100644 index 0000000000..b4358a8a3f --- /dev/null +++ b/elf/check-localplt.c @@ -0,0 +1,299 @@ +/* Show local PLT use in DSOs. + Copyright (C) 2006 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contribute by Ulrich Drepper <drepper@redhat.com>. 2006. + + 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 <stdint.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 EE(name) _EE (name, BITS) +# define _EE(name, bits) __EE (name, bits) +# define __EE(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_DYNAMIC entry. */ + size_t cnt; + E(Phdr) *dynphdr = NULL; + for (cnt = 0; cnt < phnum; ++cnt) + if (SWAP (phdr[cnt].p_type) == PT_DYNAMIC) + { + dynphdr = &phdr[cnt]; + break; + } + + if (dynphdr == NULL) + { + printf ("%s: no DYNAMIC segment found\n", fname); + return 1; + } + + /* Read the dynamic segment. */ + size_t pmemsz = SWAP(dynphdr->p_memsz); + E(Dyn) *dyn = alloca (pmemsz); + if (pread64 (fd, dyn, pmemsz, SWAP(dynphdr->p_offset)) != pmemsz) + goto read_error; + + /* Search for an DT_PLTREL, DT_JMPREL, DT_PLTRELSZ, DT_STRTAB, + DT_STRSZ, and DT_SYMTAB entries. */ + size_t pltrel_idx = SIZE_MAX; + size_t jmprel_idx = SIZE_MAX; + size_t pltrelsz_idx = SIZE_MAX; + size_t strtab_idx = SIZE_MAX; + size_t strsz_idx = SIZE_MAX; + size_t symtab_idx = SIZE_MAX; + for (cnt = 0; (cnt + 1) * sizeof (E(Dyn)) - 1 < pmemsz; ++cnt) + { + unsigned int tag = SWAP (dyn[cnt].d_tag); + + if (tag == DT_NULL) + /* We reached the end. */ + break; + + if (tag == DT_PLTREL) + pltrel_idx = cnt; + else if (tag == DT_JMPREL) + jmprel_idx = cnt; + else if (tag == DT_PLTRELSZ) + pltrelsz_idx = cnt; + else if (tag == DT_STRTAB) + strtab_idx = cnt; + else if (tag == DT_STRSZ) + strsz_idx = cnt; + else if (tag == DT_SYMTAB) + symtab_idx = cnt; + } + + if (pltrel_idx == SIZE_MAX || jmprel_idx == SIZE_MAX + || pltrelsz_idx == SIZE_MAX || strtab_idx == SIZE_MAX + || strsz_idx == SIZE_MAX || symtab_idx == SIZE_MAX) + { + puts ("not all PLT information found"); + return 1; + } + + E(Xword) relsz = SWAP (dyn[pltrelsz_idx].d_un.d_val); + + void *relmem = NULL; + char *strtab = NULL; + E(Xword) symtab_offset = 0; + + /* Find the offset of DT_JMPREL and load the data. */ + for (cnt = 0; cnt < phnum; ++cnt) + if (SWAP (phdr[cnt].p_type) == PT_LOAD) + { + E(Addr) vaddr = SWAP (phdr[cnt].p_vaddr); + E(Xword) memsz = SWAP (phdr[cnt].p_memsz); + + if (vaddr <= SWAP (dyn[jmprel_idx].d_un.d_val) + && vaddr + memsz >= SWAP (dyn[jmprel_idx].d_un.d_val) + relsz) + { + relmem = alloca (SWAP (dyn[pltrelsz_idx].d_un.d_val)); + if (pread64 (fd, relmem, relsz, + SWAP (phdr[cnt].p_offset) + + SWAP (dyn[jmprel_idx].d_un.d_val) - vaddr) + != relsz) + { + puts ("cannot read JMPREL"); + return 1; + } + } + + if (vaddr <= SWAP (dyn[symtab_idx].d_un.d_val) + && vaddr + memsz > SWAP (dyn[symtab_idx].d_un.d_val)) + symtab_offset = (SWAP (phdr[cnt].p_offset) + + SWAP (dyn[symtab_idx].d_un.d_val) - vaddr); + + if (vaddr <= SWAP (dyn[strtab_idx].d_un.d_val) + && vaddr + memsz >= (SWAP (dyn[strtab_idx].d_un.d_val) + + SWAP(dyn[strsz_idx].d_un.d_val))) + { + strtab = alloca (SWAP(dyn[strsz_idx].d_un.d_val)); + if (pread64 (fd, strtab, SWAP(dyn[strsz_idx].d_un.d_val), + SWAP (phdr[cnt].p_offset) + + SWAP (dyn[strtab_idx].d_un.d_val) - vaddr) + != SWAP(dyn[strsz_idx].d_un.d_val)) + { + puts ("cannot read STRTAB"); + return 1; + } + } + } + + if (relmem == NULL || strtab == NULL || symtab_offset == 0) + { + puts ("couldn't load PLT data"); + return 1; + } + + if (SWAP (dyn[pltrel_idx].d_un.d_val) == DT_RELA) + for (E(Rela) *rela = relmem; (char *) rela - (char *) relmem < relsz; + ++rela) + { + E(Sym) sym; + + if (pread64 (fd, &sym, sizeof (sym), + symtab_offset + + EE(R_SYM) (SWAP (rela->r_info)) * sizeof (sym)) + != sizeof (sym)) + { + puts ("cannot read symbol"); + return 1; + } + + if (sym.st_value != 0) + /* This symbol is locally defined. */ + printf ("%s: %s\n", basename (fname), strtab + SWAP (sym.st_name)); + } + else + for (E(Rel) *rel = relmem; (char *) rel - (char *) relmem < relsz; ++rel) + { + E(Sym) sym; + + if (pread64 (fd, &sym, sizeof (sym), + symtab_offset + + EE(R_SYM) (SWAP (rel->r_info)) * sizeof (sym)) + != sizeof (sym)) + { + puts ("cannot read symbol"); + return 1; + } + + if (sym.st_value != 0) + /* This symbol is locally defined. */ + printf ("%s: %s\n", basename (fname), strtab + SWAP (sym.st_name)); + } + + return 0; +} + +# undef BITS +#else + +# define BITS 32 +# include "check-localplt.c" + +# define BITS 64 +# include "check-localplt.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 |