98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
/* Relocate a shared object and resolve its references to other loaded objects.
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Copyright (C) 1995, 1996 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <link.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#include <errno.h>
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#include "dynamic-link.h"
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void
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_dl_relocate_object (struct link_map *l, struct link_map *scope[], int lazy)
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{
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if (l->l_relocated)
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return;
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if (l->l_info[DT_TEXTREL])
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{
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/* Bletch. We must make read-only segments writable
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long enough to relocate them. */
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const ElfW(Phdr) *ph;
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for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph)
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if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0)
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{
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caddr_t mapstart = ((caddr_t) l->l_addr +
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(ph->p_vaddr & ~(_dl_pagesize - 1)));
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caddr_t mapend = ((caddr_t) l->l_addr +
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((ph->p_vaddr + ph->p_memsz + _dl_pagesize - 1)
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& ~(_dl_pagesize - 1)));
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if (__mprotect (mapstart, mapend - mapstart,
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PROT_READ|PROT_WRITE) < 0)
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_dl_signal_error (errno, l->l_name,
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"cannot make segment writable for relocation");
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}
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}
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{
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/* Do the actual relocation of the object's GOT and other data. */
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const char *strtab /* String table object symbols. */
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= ((void *) l->l_addr + l->l_info[DT_STRTAB]->d_un.d_ptr);
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/* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */
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#define RESOLVE(ref, flags) \
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(_dl_lookup_symbol (strtab + (*ref)->st_name, ref, scope, \
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l->l_name, flags))
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#include "dynamic-link.h"
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ELF_DYNAMIC_RELOCATE (l, lazy);
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}
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/* Set up the PLT so its unrelocated entries will jump to
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_dl_runtime_resolve (dl-runtime.c), which will relocate them. */
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elf_machine_runtime_setup (l, lazy);
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/* Mark the object so we know ths work has been done. */
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l->l_relocated = 1;
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if (l->l_info[DT_TEXTREL])
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{
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/* Undo the protection change we made before relocating. */
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const ElfW(Phdr) *ph;
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for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph)
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if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0)
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{
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caddr_t mapstart = ((caddr_t) l->l_addr +
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(ph->p_vaddr & ~(_dl_pagesize - 1)));
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caddr_t mapend = ((caddr_t) l->l_addr +
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((ph->p_vaddr + ph->p_memsz + _dl_pagesize - 1)
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& ~(_dl_pagesize - 1)));
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int prot = 0;
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if (ph->p_flags & PF_R)
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prot |= PROT_READ;
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if (ph->p_flags & PF_X)
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prot |= PROT_EXEC;
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if (__mprotect (mapstart, mapend - mapstart, prot) < 0)
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_dl_signal_error (errno, l->l_name,
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"can't restore segment prot after reloc");
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}
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}
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}
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