299 lines
7.6 KiB
C
299 lines
7.6 KiB
C
/* Show local PLT use in DSOs.
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Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contribute by Ulrich Drepper <drepper@redhat.com>. 2006.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <byteswap.h>
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#include <elf.h>
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#include <endian.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#ifdef BITS
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# define AB(name) _AB (name, BITS)
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# define _AB(name, bits) __AB (name, bits)
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# define __AB(name, bits) name##bits
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# define E(name) _E (name, BITS)
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# define _E(name, bits) __E (name, bits)
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# define __E(name, bits) Elf##bits##_##name
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# define EE(name) _EE (name, BITS)
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# define _EE(name, bits) __EE (name, bits)
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# define __EE(name, bits) ELF##bits##_##name
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# define SWAP(val) \
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({ __typeof (val) __res; \
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if (((ehdr.e_ident[EI_DATA] == ELFDATA2MSB \
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&& BYTE_ORDER == LITTLE_ENDIAN) \
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|| (ehdr.e_ident[EI_DATA] == ELFDATA2LSB \
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&& BYTE_ORDER == BIG_ENDIAN)) \
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&& sizeof (val) != 1) \
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{ \
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if (sizeof (val) == 2) \
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__res = bswap_16 (val); \
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else if (sizeof (val) == 4) \
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__res = bswap_32 (val); \
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else \
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__res = bswap_64 (val); \
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} \
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else \
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__res = (val); \
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__res; })
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static int
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AB(handle_file) (const char *fname, int fd)
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{
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E(Ehdr) ehdr;
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if (pread (fd, &ehdr, sizeof (ehdr), 0) != sizeof (ehdr))
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{
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read_error:
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printf ("%s: read error: %m\n", fname);
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return 1;
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}
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const size_t phnum = SWAP (ehdr.e_phnum);
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const size_t phentsize = SWAP (ehdr.e_phentsize);
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/* Read the program header. */
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E(Phdr) *phdr = alloca (phentsize * phnum);
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if (pread (fd, phdr, phentsize * phnum, SWAP (ehdr.e_phoff))
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!= phentsize * phnum)
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goto read_error;
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/* Search for the PT_DYNAMIC entry. */
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size_t cnt;
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E(Phdr) *dynphdr = NULL;
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for (cnt = 0; cnt < phnum; ++cnt)
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if (SWAP (phdr[cnt].p_type) == PT_DYNAMIC)
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{
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dynphdr = &phdr[cnt];
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break;
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}
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if (dynphdr == NULL)
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{
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printf ("%s: no DYNAMIC segment found\n", fname);
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return 1;
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}
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/* Read the dynamic segment. */
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size_t pmemsz = SWAP(dynphdr->p_memsz);
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E(Dyn) *dyn = alloca (pmemsz);
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if (pread64 (fd, dyn, pmemsz, SWAP(dynphdr->p_offset)) != pmemsz)
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goto read_error;
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/* Search for an DT_PLTREL, DT_JMPREL, DT_PLTRELSZ, DT_STRTAB,
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DT_STRSZ, and DT_SYMTAB entries. */
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size_t pltrel_idx = SIZE_MAX;
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size_t jmprel_idx = SIZE_MAX;
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size_t pltrelsz_idx = SIZE_MAX;
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size_t strtab_idx = SIZE_MAX;
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size_t strsz_idx = SIZE_MAX;
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size_t symtab_idx = SIZE_MAX;
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for (cnt = 0; (cnt + 1) * sizeof (E(Dyn)) - 1 < pmemsz; ++cnt)
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{
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unsigned int tag = SWAP (dyn[cnt].d_tag);
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if (tag == DT_NULL)
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/* We reached the end. */
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break;
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if (tag == DT_PLTREL)
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pltrel_idx = cnt;
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else if (tag == DT_JMPREL)
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jmprel_idx = cnt;
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else if (tag == DT_PLTRELSZ)
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pltrelsz_idx = cnt;
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else if (tag == DT_STRTAB)
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strtab_idx = cnt;
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else if (tag == DT_STRSZ)
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strsz_idx = cnt;
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else if (tag == DT_SYMTAB)
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symtab_idx = cnt;
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}
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if (pltrel_idx == SIZE_MAX || jmprel_idx == SIZE_MAX
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|| pltrelsz_idx == SIZE_MAX || strtab_idx == SIZE_MAX
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|| strsz_idx == SIZE_MAX || symtab_idx == SIZE_MAX)
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{
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puts ("not all PLT information found");
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return 1;
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}
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E(Xword) relsz = SWAP (dyn[pltrelsz_idx].d_un.d_val);
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void *relmem = NULL;
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char *strtab = NULL;
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E(Xword) symtab_offset = 0;
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/* Find the offset of DT_JMPREL and load the data. */
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for (cnt = 0; cnt < phnum; ++cnt)
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if (SWAP (phdr[cnt].p_type) == PT_LOAD)
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{
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E(Addr) vaddr = SWAP (phdr[cnt].p_vaddr);
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E(Xword) memsz = SWAP (phdr[cnt].p_memsz);
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if (vaddr <= SWAP (dyn[jmprel_idx].d_un.d_val)
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&& vaddr + memsz >= SWAP (dyn[jmprel_idx].d_un.d_val) + relsz)
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{
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relmem = alloca (SWAP (dyn[pltrelsz_idx].d_un.d_val));
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if (pread64 (fd, relmem, relsz,
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SWAP (phdr[cnt].p_offset)
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+ SWAP (dyn[jmprel_idx].d_un.d_val) - vaddr)
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!= relsz)
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{
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puts ("cannot read JMPREL");
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return 1;
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}
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}
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if (vaddr <= SWAP (dyn[symtab_idx].d_un.d_val)
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&& vaddr + memsz > SWAP (dyn[symtab_idx].d_un.d_val))
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symtab_offset = (SWAP (phdr[cnt].p_offset)
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+ SWAP (dyn[symtab_idx].d_un.d_val) - vaddr);
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if (vaddr <= SWAP (dyn[strtab_idx].d_un.d_val)
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&& vaddr + memsz >= (SWAP (dyn[strtab_idx].d_un.d_val)
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+ SWAP(dyn[strsz_idx].d_un.d_val)))
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{
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strtab = alloca (SWAP(dyn[strsz_idx].d_un.d_val));
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if (pread64 (fd, strtab, SWAP(dyn[strsz_idx].d_un.d_val),
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SWAP (phdr[cnt].p_offset)
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+ SWAP (dyn[strtab_idx].d_un.d_val) - vaddr)
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!= SWAP(dyn[strsz_idx].d_un.d_val))
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{
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puts ("cannot read STRTAB");
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return 1;
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}
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}
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}
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if (relmem == NULL || strtab == NULL || symtab_offset == 0)
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{
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puts ("couldn't load PLT data");
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return 1;
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}
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if (SWAP (dyn[pltrel_idx].d_un.d_val) == DT_RELA)
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for (E(Rela) *rela = relmem; (char *) rela - (char *) relmem < relsz;
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++rela)
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{
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E(Sym) sym;
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if (pread64 (fd, &sym, sizeof (sym),
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symtab_offset
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+ EE(R_SYM) (SWAP (rela->r_info)) * sizeof (sym))
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!= sizeof (sym))
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{
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puts ("cannot read symbol");
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return 1;
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}
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if (sym.st_value != 0)
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/* This symbol is locally defined. */
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printf ("%s: %s\n", basename (fname), strtab + SWAP (sym.st_name));
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}
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else
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for (E(Rel) *rel = relmem; (char *) rel - (char *) relmem < relsz; ++rel)
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{
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E(Sym) sym;
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if (pread64 (fd, &sym, sizeof (sym),
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symtab_offset
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+ EE(R_SYM) (SWAP (rel->r_info)) * sizeof (sym))
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!= sizeof (sym))
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{
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puts ("cannot read symbol");
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return 1;
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}
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if (sym.st_value != 0)
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/* This symbol is locally defined. */
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printf ("%s: %s\n", basename (fname), strtab + SWAP (sym.st_name));
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}
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return 0;
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}
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# undef BITS
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#else
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# define BITS 32
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# include "check-localplt.c"
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# define BITS 64
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# include "check-localplt.c"
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static int
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handle_file (const char *fname)
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{
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int fd = open (fname, O_RDONLY);
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if (fd == -1)
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{
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printf ("cannot open %s: %m\n", fname);
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return 1;
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}
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/* Read was is supposed to be the ELF header. Read the initial
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bytes to determine whether this is a 32 or 64 bit file. */
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char ident[EI_NIDENT];
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if (read (fd, ident, EI_NIDENT) != EI_NIDENT)
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{
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printf ("%s: read error: %m\n", fname);
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close (fd);
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return 1;
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}
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if (memcmp (&ident[EI_MAG0], ELFMAG, SELFMAG) != 0)
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{
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printf ("%s: not an ELF file\n", fname);
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close (fd);
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return 1;
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}
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int result;
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if (ident[EI_CLASS] == ELFCLASS64)
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result = handle_file64 (fname, fd);
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else
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result = handle_file32 (fname, fd);
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close (fd);
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return result;
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}
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int
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main (int argc, char *argv[])
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{
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int cnt;
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int result = 0;
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for (cnt = 1; cnt < argc; ++cnt)
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result |= handle_file (argv[cnt]);
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return result;
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}
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#endif
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