/* Load a shared object at runtime, relocate it, and run its initializer.
Copyright (C) 1996-2018 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, see
<http://www.gnu.org/licenses/>. */
#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 <libc-lock.h>
#include <ldsodefs.h>
#include <sysdep-cancel.h>
#include <tls.h>
#include <stap-probe.h>
#include <atomic.h>
#include <libc-internal.h>
#include <dl-dst.h>
#include <dl-prop.h>
/* We must be careful 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;
struct link_map *map;
/* Namespace ID. */
Lmid_t nsid;
/* Original value of _ns_global_scope_pending_adds. Set by
dl_open_worker. Only valid if nsid is a real namespace
(non-negative). */
unsigned int original_global_scope_pending_adds;
/* Original parameters to the program and the current environment. */
int argc;
char **argv;
char **env;
};
/* Called in case the global scope cannot be extended. */
static void __attribute__ ((noreturn))
add_to_global_resize_failure (struct link_map *new)
{
_dl_signal_error (ENOMEM, new->l_libname->name, NULL,
N_ ("cannot extend global scope"));
}
/* Grow the global scope array for the namespace, so that all the new
global objects can be added later in add_to_global_update, without
risk of memory allocation failure. add_to_global_resize raises
exceptions for memory allocation errors. */
static void
add_to_global_resize (struct link_map *new)
{
struct link_namespaces *ns = &GL (dl_ns)[new->l_ns];
/* Count the objects we have to put in the global scope. */
unsigned int to_add = 0;
for (unsigned int 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 (__builtin_add_overflow (ns->_ns_global_scope_pending_adds, to_add,
&ns->_ns_global_scope_pending_adds))
add_to_global_resize_failure (new);
unsigned int new_size = 0; /* 0 means no new allocation. */
void *old_global = NULL; /* Old allocation if free-able. */
/* Minimum required element count for resizing. Adjusted below for
an exponential resizing policy. */
size_t required_new_size;
if (__builtin_add_overflow (ns->_ns_main_searchlist->r_nlist,
ns->_ns_global_scope_pending_adds,
&required_new_size))
add_to_global_resize_failure (new);
if (ns->_ns_global_scope_alloc == 0)
{
if (__builtin_add_overflow (required_new_size, 8, &new_size))
add_to_global_resize_failure (new);
}
else if (required_new_size > ns->_ns_global_scope_alloc)
{
if (__builtin_mul_overflow (required_new_size, 2, &new_size))
add_to_global_resize_failure (new);
/* The old array was allocated with our malloc, not the minimal
malloc. */
old_global = ns->_ns_main_searchlist->r_list;
}
if (new_size > 0)
{
size_t allocation_size;
if (__builtin_mul_overflow (new_size, sizeof (struct link_map *),
&allocation_size))
add_to_global_resize_failure (new);
struct link_map **new_global = malloc (allocation_size);
if (new_global == NULL)
add_to_global_resize_failure (new);
/* Copy over the old entries. */
memcpy (new_global, ns->_ns_main_searchlist->r_list,
ns->_ns_main_searchlist->r_nlist * sizeof (struct link_map *));
ns->_ns_global_scope_alloc = new_size;
ns->_ns_main_searchlist->r_list = new_global;
if (!RTLD_SINGLE_THREAD_P)
THREAD_GSCOPE_WAIT ();
free (old_global);
}
}
/* Actually add the new global objects to the global scope. Must be
called after add_to_global_resize. This function cannot fail. */
static void
add_to_global_update (struct link_map *new)
{
struct link_namespaces *ns = &GL (dl_ns)[new->l_ns];
/* Now add the new entries. */
unsigned int new_nlist = ns->_ns_main_searchlist->r_nlist;
for (unsigned int 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;
/* The array has been resized by add_to_global_resize. */
assert (new_nlist < ns->_ns_global_scope_alloc);
ns->_ns_main_searchlist->r_list[new_nlist++] = map;
/* We modify the global scope. Report this. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES))
_dl_debug_printf ("\nadd %s [%lu] to global scope\n",
map->l_name, map->l_ns);
}
}
/* Some of the pending adds have been performed by the loop above.
Adjust the counter accordingly. */
unsigned int added = new_nlist - ns->_ns_main_searchlist->r_nlist;
assert (added <= ns->_ns_global_scope_pending_adds);
ns->_ns_global_scope_pending_adds -= added;
atomic_write_barrier ();
ns->_ns_main_searchlist->r_nlist = new_nlist;
}
/* Search link maps in all namespaces for the DSO that contains the object at
address ADDR. Returns the pointer to the link map of the matching DSO, or
NULL if a match is not found. */
struct link_map *
_dl_find_dso_for_object (const ElfW(Addr) addr)
{
struct link_map *l;
/* Find the highest-addressed object that ADDR is not below. */
for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
if (addr >= l->l_map_start && addr < l->l_map_end
&& (l->l_contiguous
|| _dl_addr_inside_object (l, (ElfW(Addr)) addr)))
{
assert (ns == l->l_ns);
return l;
}
return NULL;
}
rtld_hidden_def (_dl_find_dso_for_object);
/* struct dl_init_args and call_dl_init are used to call _dl_init with
exception handling disabled. */
struct dl_init_args
{
struct link_map *new;
int argc;
char **argv;
char **env;
};
static void
call_dl_init (void *closure)
{
struct dl_init_args *args = closure;
_dl_init (args->new, args->argc, args->argv, args->env);
}
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 *call_map = NULL;
/* Determine the caller's map if necessary. This is needed in case
we have a DST, when we don't know the namespace ID we have to put
the new object in, or when the file name has no path in which
case we need to look along the RUNPATH/RPATH of the caller. */
const char *dst = strchr (file, '$');
if (dst != NULL || args->nsid == __LM_ID_CALLER
|| strchr (file, '/') == NULL)
{
const void *caller_dlopen = args->caller_dlopen;
/* We have to find out from which object the caller is calling.
By default we assume this is the main application. */
call_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
struct link_map *l = _dl_find_dso_for_object ((ElfW(Addr)) caller_dlopen);
if (l)
call_map = l;
if (args->nsid == __LM_ID_CALLER)
args->nsid = call_map->l_ns;
}
/* Retain the old value, so that it can be restored. */
args->original_global_scope_pending_adds
= GL (dl_ns)[args->nsid]._ns_global_scope_pending_adds;
/* One might be tempted to assert that we are RT_CONSISTENT at this point, but that
may not be true if this is a recursive call to dlopen. */
_dl_debug_initialize (0, args->nsid);
/* Load the named object. */
struct link_map *new;
args->map = new = _dl_map_object (call_map, file, lt_loaded, 0,
mode | __RTLD_CALLMAP, args->nsid);
/* 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;
}
/* Mark the object as not deletable if the RTLD_NODELETE flags was passed.
Do this early so that we don't skip marking the object if it was
already loaded. */
if (__glibc_unlikely (mode & RTLD_NODELETE))
new->l_flags_1 |= DF_1_NODELETE;
if (__glibc_unlikely (mode & __RTLD_SPROF))
/* This happens only if we load a DSO for 'sprof'. */
return;
/* This object is directly loaded. */
++new->l_direct_opencount;
/* It was already open. */
if (__glibc_unlikely (new->l_searchlist.r_list != NULL))
{
/* Let the user know about the opencount. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
_dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
new->l_name, new->l_ns, new->l_direct_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)
{
add_to_global_resize (new);
add_to_global_update (new);
}
assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
return;
}
/* Load that object's dependencies. */
_dl_map_object_deps (new, NULL, 0, 0,
mode & (__RTLD_DLOPEN | RTLD_DEEPBIND | __RTLD_AUDIT));
/* So far, so good. Now check the versions. */
for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
if (new->l_searchlist.r_list[i]->l_real->l_versions == NULL)
(void) _dl_check_map_versions (new->l_searchlist.r_list[i]->l_real,
0, 0);
#ifdef SHARED
/* Auditing checkpoint: we have added all objects. */
if (__glibc_unlikely (GLRO(dl_naudit) > 0))
{
struct link_map *head = GL(dl_ns)[new->l_ns]._ns_loaded;
/* Do not call the functions for any auditing object. */
if (head->l_auditing == 0)
{
struct audit_ifaces *afct = GLRO(dl_audit);
for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
{
if (afct->activity != NULL)
afct->activity (&head->l_audit[cnt].cookie, LA_ACT_CONSISTENT);
afct = afct->next;
}
}
}
#endif
/* Notify the debugger all new objects are now ready to go. */
struct r_debug *r = _dl_debug_initialize (0, args->nsid);
r->r_state = RT_CONSISTENT;
_dl_debug_state ();
LIBC_PROBE (map_complete, 3, args->nsid, r, new);
/* Print scope information. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES))
_dl_show_scope (new, 0);
/* Only do lazy relocation if `LD_BIND_NOW' is not set. */
int reloc_mode = mode & __RTLD_AUDIT;
if (GLRO(dl_lazy))
reloc_mode |= mode & RTLD_LAZY;
/* Sort the objects by dependency for the relocation process. This
allows IFUNC relocations to work and it also means copy
relocation of dependencies are if necessary overwritten. */
unsigned int nmaps = 0;
struct link_map *l = new;
do
{
if (! l->l_real->l_relocated)
++nmaps;
l = l->l_next;
}
while (l != NULL);
struct link_map *maps[nmaps];
nmaps = 0;
l = new;
do
{
if (! l->l_real->l_relocated)
maps[nmaps++] = l;
l = l->l_next;
}
while (l != NULL);
_dl_sort_maps (maps, nmaps, NULL, false);
int relocation_in_progress = 0;
for (unsigned int i = nmaps; i-- > 0; )
{
l = maps[i];
if (! relocation_in_progress)
{
/* Notify the debugger that relocations are about to happen. */
LIBC_PROBE (reloc_start, 2, args->nsid, r);
relocation_in_progress = 1;
}
#ifdef SHARED
if (__glibc_unlikely (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 it was NULL but is not NULL afterwards we must
start the profiling. */
struct link_map *old_profile_map = GL(dl_profile_map);
_dl_relocate_object (l, l->l_scope, reloc_mode | RTLD_LAZY, 1);
if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
{
/* We must prepare the profiling. */
_dl_start_profile ();
/* Prevent unloading the object. */
GL(dl_profile_map)->l_flags_1 |= DF_1_NODELETE;
}
}
else
#endif
_dl_relocate_object (l, l->l_scope, reloc_mode, 0);
}
/* NB: Workaround for [BZ #20839] which doesn't remove the NODELETE
object when _dl_open_check throws an exception. Move it after
relocation to avoid leaving the NODELETE object mapped without
relocation. */
_dl_open_check (new);
/* If the file is not loaded now as a dependency, add the search
list of the newly loaded object to the scope. */
bool any_tls = false;
unsigned int first_static_tls = new->l_searchlist.r_nlist;
for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
{
struct link_map *imap = new->l_searchlist.r_list[i];
int from_scope = 0;
/* If the initializer has been called already, the object has
not been loaded here and now. */
if (imap->l_init_called && imap->l_type == lt_loaded)
{
struct r_scope_elem **runp = imap->l_scope;
size_t cnt = 0;
while (*runp != NULL)
{
if (*runp == &new->l_searchlist)
break;
++cnt;
++runp;
}
if (*runp != NULL)
/* Avoid duplicates. */
continue;
if (__glibc_unlikely (cnt + 1 >= imap->l_scope_max))
{
/* The 'r_scope' array is too small. Allocate a new one
dynamically. */
size_t new_size;
struct r_scope_elem **newp;
#define SCOPE_ELEMS(imap) \
(sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
if (imap->l_scope != imap->l_scope_mem
&& imap->l_scope_max < SCOPE_ELEMS (imap))
{
new_size = SCOPE_ELEMS (imap);
newp = imap->l_scope_mem;
}
else
{
new_size = imap->l_scope_max * 2;
newp = (struct r_scope_elem **)
malloc (new_size * sizeof (struct r_scope_elem *));
if (newp == NULL)
_dl_signal_error (ENOMEM, "dlopen", NULL,
N_("cannot create scope list"));
}
memcpy (newp, imap->l_scope, cnt * sizeof (imap->l_scope[0]));
struct r_scope_elem **old = imap->l_scope;
imap->l_scope = newp;
if (old != imap->l_scope_mem)
_dl_scope_free (old);
imap->l_scope_max = new_size;
}
/* First terminate the extended list. Otherwise a thread
might use the new last element and then use the garbage
at offset IDX+1. */
imap->l_scope[cnt + 1] = NULL;
atomic_write_barrier ();
imap->l_scope[cnt] = &new->l_searchlist;
/* Print only new scope information. */
from_scope = cnt;
}
/* Only add TLS memory if this object is loaded now and
therefore is not yet initialized. */
else if (! imap->l_init_called
/* Only if the module defines thread local data. */
&& __builtin_expect (imap->l_tls_blocksize > 0, 0))
{
/* Now that we know the object is loaded successfully add
modules containing TLS data to the slot info table. We
might have to increase its size. */
_dl_add_to_slotinfo (imap);
if (imap->l_need_tls_init
&& first_static_tls == new->l_searchlist.r_nlist)
first_static_tls = i;
/* We have to bump the generation counter. */
any_tls = true;
}
/* Print scope information. */
if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES))
_dl_show_scope (imap, from_scope);
}
/* Bump the generation number if necessary. */
if (any_tls && __builtin_expect (++GL(dl_tls_generation) == 0, 0))
_dl_fatal_printf (N_("\
TLS generation counter wrapped! Please report this."));
/* We need a second pass for static tls data, because _dl_update_slotinfo
must not be run while calls to _dl_add_to_slotinfo are still pending. */
for (unsigned int i = first_static_tls; i < new->l_searchlist.r_nlist; ++i)
{
struct link_map *imap = new->l_searchlist.r_list[i];
if (imap->l_need_tls_init
&& ! imap->l_init_called
&& imap->l_tls_blocksize > 0)
{
/* For static TLS we have to allocate the memory here and
now, but we can delay updating the DTV. */
imap->l_need_tls_init = 0;
#ifdef SHARED
/* Update the slot information data for at least the
generation of the DSO we are allocating data for. */
_dl_update_slotinfo (imap->l_tls_modid);
#endif
GL(dl_init_static_tls) (imap);
assert (imap->l_need_tls_init == 0);
}
}
/* Notify the debugger all new objects have been relocated. */
if (relocation_in_progress)
LIBC_PROBE (reloc_complete, 3, args->nsid, r, new);
#ifndef SHARED
DL_STATIC_INIT (new);
#endif
/* Perform the necessary allocations for adding new global objects
to the global scope below, via add_to_global_update. */
if (mode & RTLD_GLOBAL)
add_to_global_resize (new);
/* Run the initializer functions of new objects. Temporarily
disable the exception handler, so that lazy binding failures are
fatal. */
{
struct dl_init_args init_args =
{
.new = new,
.argc = args->argc,
.argv = args->argv,
.env = args->env
};
_dl_catch_exception (NULL, call_dl_init, &init_args);
}
/* Now we can make the new map available in the global scope. */
if (mode & RTLD_GLOBAL)
add_to_global_update (new);
#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 (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
_dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
new->l_name, new->l_ns, new->l_direct_opencount);
}
void *
_dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid,
int argc, char *argv[], char *env[])
{
if ((mode & RTLD_BINDING_MASK) == 0)
/* One of the flags must be set. */
_dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
/* Make sure we are alone. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
if (__glibc_unlikely (nsid == LM_ID_NEWLM))
{
/* Find a new namespace. */
for (nsid = 1; DL_NNS > 1 && nsid < GL(dl_nns); ++nsid)
if (GL(dl_ns)[nsid]._ns_loaded == NULL)
break;
if (__glibc_unlikely (nsid == DL_NNS))
{
/* No more namespace available. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
_dl_signal_error (EINVAL, file, NULL, N_("\
no more namespaces available for dlmopen()"));
}
else if (nsid == GL(dl_nns))
{
__rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
++GL(dl_nns);
}
_dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT;
}
/* Never allow loading a DSO in a namespace which is empty. Such
direct placements is only causing problems. Also don't allow
loading into a namespace used for auditing. */
else if (__glibc_unlikely (nsid != LM_ID_BASE && nsid != __LM_ID_CALLER)
&& (__glibc_unlikely (nsid < 0 || nsid >= GL(dl_nns))
/* This prevents the [NSID] index expressions from being
evaluated, so the compiler won't think that we are
accessing an invalid index here in the !SHARED case where
DL_NNS is 1 and so any NSID != 0 is invalid. */
|| DL_NNS == 1
|| GL(dl_ns)[nsid]._ns_nloaded == 0
|| GL(dl_ns)[nsid]._ns_loaded->l_auditing))
_dl_signal_error (EINVAL, file, NULL,
N_("invalid target namespace in dlmopen()"));
struct dl_open_args args;
args.file = file;
args.mode = mode;
args.caller_dlopen = caller_dlopen;
args.map = NULL;
args.nsid = nsid;
args.argc = argc;
args.argv = argv;
args.env = env;
struct dl_exception exception;
int errcode = _dl_catch_exception (&exception, dl_open_worker, &args);
#if defined USE_LDCONFIG && !defined MAP_COPY
/* We must unmap the cache file. */
_dl_unload_cache ();
#endif
/* Do this for both the error and success cases. The old value has
only been determined if the namespace ID was assigned (i.e., it
is not __LM_ID_CALLER). In the success case, we actually may
have consumed more pending adds than planned (because the local
scopes overlap in case of a recursive dlopen, the inner dlopen
doing some of the globalization work of the outer dlopen), so the
old pending adds value is larger than absolutely necessary.
Since it is just a conservative upper bound, this is harmless.
The top-level dlopen call will restore the field to zero. */
if (args.nsid >= 0)
GL (dl_ns)[args.nsid]._ns_global_scope_pending_adds
= args.original_global_scope_pending_adds;
/* See if an error occurred during loading. */
if (__glibc_unlikely (exception.errstring != NULL))
{
/* Remove the object from memory. It may be in an inconsistent
state if relocation failed, for example. */
if (args.map)
{
/* Maybe some of the modules which were loaded use 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. There is no need to do this when we are
loading the auditing DSOs since TLS has not yet been set
up. */
if ((mode & __RTLD_AUDIT) == 0)
GL(dl_tls_dtv_gaps) = true;
_dl_close_worker (args.map, true);
}
assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
/* Release the lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
/* Reraise the error. */
_dl_signal_exception (errcode, &exception, NULL);
}
assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
/* Release the lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
return args.map;
}
void
_dl_show_scope (struct link_map *l, int from)
{
_dl_debug_printf ("object=%s [%lu]\n",
DSO_FILENAME (l->l_name), l->l_ns);
if (l->l_scope != NULL)
for (int scope_cnt = from; l->l_scope[scope_cnt] != NULL; ++scope_cnt)
{
_dl_debug_printf (" scope %u:", scope_cnt);
for (unsigned int cnt = 0; cnt < l->l_scope[scope_cnt]->r_nlist; ++cnt)
if (*l->l_scope[scope_cnt]->r_list[cnt]->l_name)
_dl_debug_printf_c (" %s",
l->l_scope[scope_cnt]->r_list[cnt]->l_name);
else
_dl_debug_printf_c (" %s", RTLD_PROGNAME);
_dl_debug_printf_c ("\n");
}
else
_dl_debug_printf (" no scope\n");
_dl_debug_printf ("\n");
}