glibc/elf/dl-open.c

614 lines
18 KiB
C

/* Load a shared object at runtime, relocate it, and run its initializer.
Copyright (C) 1996-2001, 2002, 2003, 2004 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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 <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <libintl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h> /* Check whether MAP_COPY is defined. */
#include <sys/param.h>
#include <bits/libc-lock.h>
#include <ldsodefs.h>
#include <bp-sym.h>
#include <caller.h>
#include <dl-dst.h>
#ifndef SHARED
/* Giving this initialized value preallocates some surplus bytes in the
static TLS area, see __libc_setup_tls (libc-tls.c). */
size_t _dl_tls_static_size = 2048;
#endif
extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
void (*dl_main) (const ElfW(Phdr) *phdr,
ElfW(Word) phnum,
ElfW(Addr) *user_entry));
weak_extern (BP_SYM (_dl_sysdep_start))
extern int __libc_multiple_libcs; /* Defined in init-first.c. */
extern int __libc_argc attribute_hidden;
extern char **__libc_argv attribute_hidden;
extern char **__environ;
/* Undefine the following for debugging. */
/* #define SCOPE_DEBUG 1 */
#ifdef SCOPE_DEBUG
static void show_scope (struct link_map *new);
#endif
/* We must be carefull not to leave us in an inconsistent state. Thus we
catch any error and re-raise it after cleaning up. */
struct dl_open_args
{
const char *file;
int mode;
/* This is the caller of the dlopen() function. */
const void *caller_dlopen;
/* This is the caller if _dl_open(). */
const void *caller_dl_open;
struct link_map *map;
};
static int
add_to_global (struct link_map *new)
{
struct link_map **new_global;
unsigned int to_add = 0;
unsigned int cnt;
/* Count the objects we have to put in the global scope. */
for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
if (new->l_searchlist.r_list[cnt]->l_global == 0)
++to_add;
/* The symbols of the new objects and its dependencies are to be
introduced into the global scope that will be used to resolve
references from other dynamically-loaded objects.
The global scope is the searchlist in the main link map. We
extend this list if necessary. There is one problem though:
since this structure was allocated very early (before the libc
is loaded) the memory it uses is allocated by the malloc()-stub
in the ld.so. When we come here these functions are not used
anymore. Instead the malloc() implementation of the libc is
used. But this means the block from the main map cannot be used
in an realloc() call. Therefore we allocate a completely new
array the first time we have to add something to the locale scope. */
if (GL(dl_global_scope_alloc) == 0)
{
/* This is the first dynamic object given global scope. */
GL(dl_global_scope_alloc) = GL(dl_main_searchlist)->r_nlist + to_add + 8;
new_global = (struct link_map **)
malloc (GL(dl_global_scope_alloc) * sizeof (struct link_map *));
if (new_global == NULL)
{
GL(dl_global_scope_alloc) = 0;
nomem:
GLRO(dl_signal_error) (ENOMEM, new->l_libname->name, NULL,
N_("cannot extend global scope"));
return 1;
}
/* Copy over the old entries. */
memcpy (new_global, GL(dl_main_searchlist)->r_list,
(GL(dl_main_searchlist)->r_nlist * sizeof (struct link_map *)));
GL(dl_main_searchlist)->r_list = new_global;
}
else if (GL(dl_main_searchlist)->r_nlist + to_add
> GL(dl_global_scope_alloc))
{
/* We have to extend the existing array of link maps in the
main map. */
new_global = (struct link_map **)
realloc (GL(dl_main_searchlist)->r_list,
((GL(dl_global_scope_alloc) + to_add + 8)
* sizeof (struct link_map *)));
if (new_global == NULL)
goto nomem;
GL(dl_global_scope_alloc) += to_add + 8;
GL(dl_main_searchlist)->r_list = new_global;
}
/* Now add the new entries. */
for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
{
struct link_map *map = new->l_searchlist.r_list[cnt];
if (map->l_global == 0)
{
map->l_global = 1;
GL(dl_main_searchlist)->r_list[GL(dl_main_searchlist)->r_nlist]
= map;
++GL(dl_main_searchlist)->r_nlist;
}
}
return 0;
}
static void
dl_open_worker (void *a)
{
struct dl_open_args *args = a;
const char *file = args->file;
int mode = args->mode;
struct link_map *new, *l;
const char *dst;
int lazy;
unsigned int i;
#ifdef USE_TLS
bool any_tls;
#endif
/* Check whether _dl_open() has been called from a valid DSO. */
if (__check_caller (args->caller_dl_open, allow_libc|allow_libdl) != 0)
GLRO(dl_signal_error) (0, "dlopen", NULL, N_("invalid caller"));
/* Maybe we have to expand a DST. */
dst = strchr (file, '$');
if (__builtin_expect (dst != NULL, 0))
{
const void *caller_dlopen = args->caller_dlopen;
size_t len = strlen (file);
size_t required;
struct link_map *call_map;
char *new_file;
/* DSTs must not appear in SUID/SGID programs. */
if (__libc_enable_secure)
/* This is an error. */
GLRO(dl_signal_error) (0, "dlopen", NULL,
N_("DST not allowed in SUID/SGID programs"));
/* We have to find out from which object the caller is calling. */
call_map = NULL;
for (l = GL(dl_loaded); l; l = l->l_next)
if (caller_dlopen >= (const void *) l->l_map_start
&& caller_dlopen < (const void *) l->l_map_end)
{
/* There must be exactly one DSO for the range of the virtual
memory. Otherwise something is really broken. */
call_map = l;
break;
}
if (call_map == NULL)
/* In this case we assume this is the main application. */
call_map = GL(dl_loaded);
/* Determine how much space we need. We have to allocate the
memory locally. */
required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));
/* Get space for the new file name. */
new_file = (char *) alloca (required + 1);
/* Generate the new file name. */
_dl_dst_substitute (call_map, file, new_file, 0);
/* If the substitution failed don't try to load. */
if (*new_file == '\0')
GLRO(dl_signal_error) (0, "dlopen", NULL,
N_("empty dynamic string token substitution"));
/* Now we have a new file name. */
file = new_file;
}
/* Load the named object. */
args->map = new = GLRO(dl_map_object) (NULL, file, 0, lt_loaded, 0, mode);
/* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
set and the object is not already loaded. */
if (new == NULL)
{
assert (mode & RTLD_NOLOAD);
return;
}
if (__builtin_expect (mode & __RTLD_SPROF, 0))
/* This happens only if we load a DSO for 'sprof'. */
return;
/* It was already open. */
if (__builtin_expect (new->l_searchlist.r_list != NULL, 0))
{
/* Let the user know about the opencount. */
if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
GLRO(dl_debug_printf) ("opening file=%s; opencount == %u\n\n",
new->l_name, new->l_opencount);
/* If the user requested the object to be in the global namespace
but it is not so far, add it now. */
if ((mode & RTLD_GLOBAL) && new->l_global == 0)
(void) add_to_global (new);
/* Increment just the reference counter of the object. */
++new->l_opencount;
return;
}
/* Load that object's dependencies. */
GLRO(dl_map_object_deps) (new, NULL, 0, 0, mode & __RTLD_DLOPEN);
/* So far, so good. Now check the versions. */
for (i = 0; i < new->l_searchlist.r_nlist; ++i)
if (new->l_searchlist.r_list[i]->l_versions == NULL)
(void) GLRO(dl_check_map_versions) (new->l_searchlist.r_list[i], 0, 0);
#ifdef SCOPE_DEBUG
show_scope (new);
#endif
/* Only do lazy relocation if `LD_BIND_NOW' is not set. */
lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && GLRO(dl_lazy);
/* Relocate the objects loaded. We do this in reverse order so that copy
relocs of earlier objects overwrite the data written by later objects. */
l = new;
while (l->l_next)
l = l->l_next;
while (1)
{
if (! l->l_relocated)
{
#ifdef SHARED
if (GLRO(dl_profile) != NULL)
{
/* If this here is the shared object which we want to profile
make sure the profile is started. We can find out whether
this is necessary or not by observing the `_dl_profile_map'
variable. If was NULL but is not NULL afterwars we must
start the profiling. */
struct link_map *old_profile_map = GL(dl_profile_map);
GLRO(dl_relocate_object) (l, l->l_scope, 1, 1);
if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
/* We must prepare the profiling. */
GLRO(dl_start_profile) ();
}
else
#endif
GLRO(dl_relocate_object) (l, l->l_scope, lazy, 0);
}
if (l == new)
break;
l = l->l_prev;
}
#ifdef USE_TLS
/* Do static TLS initialization now if it has been delayed because
the TLS template might not be fully relocated at _dl_allocate_static_tls
time. */
for (l = new; l; l = l->l_next)
if (l->l_need_tls_init)
{
l->l_need_tls_init = 0;
GL(dl_init_static_tls) (l);
}
/* We normally don't bump the TLS generation counter. There must be
actually a need to do this. */
any_tls = false;
#endif
/* Increment the open count for all dependencies. If the file is
not loaded as a dependency here add the search list of the newly
loaded object to the scope. */
for (i = 0; i < new->l_searchlist.r_nlist; ++i)
if (++new->l_searchlist.r_list[i]->l_opencount > 1
&& new->l_searchlist.r_list[i]->l_type == lt_loaded)
{
struct link_map *imap = new->l_searchlist.r_list[i];
struct r_scope_elem **runp = imap->l_scope;
size_t cnt = 0;
while (*runp != NULL)
{
/* This can happen if imap was just loaded, but during
relocation had l_opencount bumped because of relocation
dependency. Avoid duplicates in l_scope. */
if (__builtin_expect (*runp == &new->l_searchlist, 0))
break;
++cnt;
++runp;
}
if (*runp != NULL)
/* Avoid duplicates. */
continue;
if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
{
/* The 'r_scope' array is too small. Allocate a new one
dynamically. */
struct r_scope_elem **newp;
size_t new_size = imap->l_scope_max * 2;
if (imap->l_scope == imap->l_scope_mem)
{
newp = (struct r_scope_elem **)
malloc (new_size * sizeof (struct r_scope_elem *));
if (newp == NULL)
GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL,
N_("cannot create scope list"));
imap->l_scope = memcpy (newp, imap->l_scope,
cnt * sizeof (imap->l_scope[0]));
}
else
{
newp = (struct r_scope_elem **)
realloc (imap->l_scope,
new_size * sizeof (struct r_scope_elem *));
if (newp == NULL)
GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL,
N_("cannot create scope list"));
imap->l_scope = newp;
}
imap->l_scope_max = new_size;
}
imap->l_scope[cnt++] = &new->l_searchlist;
imap->l_scope[cnt] = NULL;
}
#if USE_TLS
else if (new->l_searchlist.r_list[i]->l_opencount == 1
/* Only if the module defines thread local data. */
&& __builtin_expect (new->l_searchlist.r_list[i]->l_tls_blocksize
> 0, 0))
{
/* Now that we know the object is loaded successfully add
modules containing TLS data to the dtv info table. We
might have to increase its size. */
struct dtv_slotinfo_list *listp;
struct dtv_slotinfo_list *prevp;
size_t idx = new->l_searchlist.r_list[i]->l_tls_modid;
assert (new->l_searchlist.r_list[i]->l_type == lt_loaded);
/* Find the place in the dtv slotinfo list. */
listp = GL(dl_tls_dtv_slotinfo_list);
prevp = NULL; /* Needed to shut up gcc. */
do
{
/* Does it fit in the array of this list element? */
if (idx < listp->len)
break;
idx -= listp->len;
prevp = listp;
listp = listp->next;
}
while (listp != NULL);
if (listp == NULL)
{
/* When we come here it means we have to add a new element
to the slotinfo list. And the new module must be in
the first slot. */
assert (idx == 0);
listp = prevp->next = (struct dtv_slotinfo_list *)
malloc (sizeof (struct dtv_slotinfo_list)
+ TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
if (listp == NULL)
{
/* We ran out of memory. We will simply fail this
call but don't undo anything we did so far. The
application will crash or be terminated anyway very
soon. */
/* We have to do this since some entries in the dtv
slotinfo array might already point to this
generation. */
++GL(dl_tls_generation);
GLRO(dl_signal_error) (ENOMEM, "dlopen", NULL, N_("\
cannot create TLS data structures"));
}
listp->len = TLS_SLOTINFO_SURPLUS;
listp->next = NULL;
memset (listp->slotinfo, '\0',
TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo));
}
/* Add the information into the slotinfo data structure. */
listp->slotinfo[idx].map = new->l_searchlist.r_list[i];
listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1;
/* We have to bump the generation counter. */
any_tls = true;
}
/* Bump the generation number if necessary. */
if (any_tls)
if (__builtin_expect (++GL(dl_tls_generation) == 0, 0))
__libc_fatal (_("TLS generation counter wrapped! Please send report with the 'glibcbug' script."));
#endif
/* Run the initializer functions of new objects. */
GLRO(dl_init) (new, __libc_argc, __libc_argv, __environ);
/* Now we can make the new map available in the global scope. */
if (mode & RTLD_GLOBAL)
/* Move the object in the global namespace. */
if (add_to_global (new) != 0)
/* It failed. */
return;
/* Mark the object as not deletable if the RTLD_NODELETE flags was
passed. */
if (__builtin_expect (mode & RTLD_NODELETE, 0))
new->l_flags_1 |= DF_1_NODELETE;
#ifndef SHARED
/* We must be the static _dl_open in libc.a. A static program that
has loaded a dynamic object now has competition. */
__libc_multiple_libcs = 1;
#endif
/* Let the user know about the opencount. */
if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
GLRO(dl_debug_printf) ("opening file=%s; opencount == %u\n\n",
new->l_name, new->l_opencount);
}
void *
internal_function
_dl_open (const char *file, int mode, const void *caller_dlopen)
{
struct dl_open_args args;
const char *objname;
const char *errstring;
int errcode;
if ((mode & RTLD_BINDING_MASK) == 0)
/* One of the flags must be set. */
GLRO(dl_signal_error) (EINVAL, file, NULL,
N_("invalid mode for dlopen()"));
/* Make sure we are alone. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
args.file = file;
args.mode = mode;
args.caller_dlopen = caller_dlopen;
args.caller_dl_open = RETURN_ADDRESS (0);
args.map = NULL;
errcode = GLRO(dl_catch_error) (&objname, &errstring, dl_open_worker, &args);
#ifndef MAP_COPY
/* We must munmap() the cache file. */
GLRO(dl_unload_cache) ();
#endif
/* Release the lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
if (__builtin_expect (errstring != NULL, 0))
{
/* Some error occurred during loading. */
char *local_errstring;
size_t len_errstring;
/* Remove the object from memory. It may be in an inconsistent
state if relocation failed, for example. */
if (args.map)
{
unsigned int i;
/* Increment open counters for all objects since this
sometimes has not happened yet. */
if (args.map->l_searchlist.r_list[0]->l_opencount == 0)
for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
++args.map->l_searchlist.r_list[i]->l_opencount;
#ifdef USE_TLS
/* Maybe some of the modules which were loaded uses TLS.
Since it will be removed in the following _dl_close call
we have to mark the dtv array as having gaps to fill
the holes. This is a pessimistic assumption which won't
hurt if not true. */
GL(dl_tls_dtv_gaps) = true;
#endif
_dl_close (args.map);
}
/* Make a local copy of the error string so that we can release the
memory allocated for it. */
len_errstring = strlen (errstring) + 1;
if (objname == errstring + len_errstring)
{
size_t total_len = len_errstring + strlen (objname) + 1;
local_errstring = alloca (total_len);
memcpy (local_errstring, errstring, total_len);
objname = local_errstring + len_errstring;
}
else
{
local_errstring = alloca (len_errstring);
memcpy (local_errstring, errstring, len_errstring);
}
if (errstring != _dl_out_of_memory)
free ((char *) errstring);
/* Reraise the error. */
GLRO(dl_signal_error) (errcode, objname, NULL, local_errstring);
}
#ifndef SHARED
DL_STATIC_INIT (args.map);
#endif
return args.map;
}
libc_hidden_def (_dl_open)
#ifdef SCOPE_DEBUG
#include <unistd.h>
static void
show_scope (struct link_map *new)
{
int scope_cnt;
for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
{
char numbuf[2];
unsigned int cnt;
numbuf[0] = '0' + scope_cnt;
numbuf[1] = '\0';
_dl_printf ("scope %s:", numbuf);
for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
_dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name);
else
_dl_printf (" <main>");
_dl_printf ("\n");
}
}
#endif