| /* Load the dependencies of a mapped object. |
| 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 <atomic.h> |
| #include <assert.h> |
| #include <dlfcn.h> |
| #include <errno.h> |
| #include <libintl.h> |
| #include <stddef.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <sys/param.h> |
| #include <ldsodefs.h> |
| |
| #include <dl-dst.h> |
| |
| /* Whether an shared object references one or more auxiliary objects |
| is signaled by the AUXTAG entry in l_info. */ |
| #define AUXTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \ |
| + DT_EXTRATAGIDX (DT_AUXILIARY)) |
| /* Whether an shared object references one or more auxiliary objects |
| is signaled by the AUXTAG entry in l_info. */ |
| #define FILTERTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \ |
| + DT_EXTRATAGIDX (DT_FILTER)) |
| |
| |
| /* When loading auxiliary objects we must ignore errors. It's ok if |
| an object is missing. */ |
| struct openaux_args |
| { |
| /* The arguments to openaux. */ |
| struct link_map *map; |
| int trace_mode; |
| int open_mode; |
| const char *strtab; |
| const char *name; |
| |
| /* The return value of openaux. */ |
| struct link_map *aux; |
| }; |
| |
| static void |
| openaux (void *a) |
| { |
| struct openaux_args *args = (struct openaux_args *) a; |
| |
| args->aux = _dl_map_object (args->map, args->name, 0, |
| (args->map->l_type == lt_executable |
| ? lt_library : args->map->l_type), |
| args->trace_mode, args->open_mode, |
| args->map->l_ns); |
| } |
| |
| static ptrdiff_t |
| _dl_build_local_scope (struct link_map **list, struct link_map *map) |
| { |
| struct link_map **p = list; |
| struct link_map **q; |
| |
| *p++ = map; |
| map->l_reserved = 1; |
| if (map->l_initfini) |
| for (q = map->l_initfini + 1; *q; ++q) |
| if (! (*q)->l_reserved) |
| p += _dl_build_local_scope (p, *q); |
| return p - list; |
| } |
| |
| |
| /* We use a very special kind of list to track the path |
| through the list of loaded shared objects. We have to |
| produce a flat list with unique members of all involved objects. |
| */ |
| struct list |
| { |
| int done; /* Nonzero if this map was processed. */ |
| struct link_map *map; /* The data. */ |
| struct list *next; /* Elements for normal list. */ |
| }; |
| |
| |
| /* Macro to expand DST. It is an macro since we use `alloca'. */ |
| #define expand_dst(l, str, fatal) \ |
| ({ \ |
| const char *__str = (str); \ |
| const char *__result = __str; \ |
| size_t __dst_cnt = DL_DST_COUNT (__str); \ |
| \ |
| if (__dst_cnt != 0) \ |
| { \ |
| char *__newp; \ |
| \ |
| /* DST must not appear in SUID/SGID programs. */ \ |
| if (__libc_enable_secure) \ |
| _dl_signal_error (0, __str, NULL, N_("\ |
| DST not allowed in SUID/SGID programs")); \ |
| \ |
| __newp = (char *) alloca (DL_DST_REQUIRED (l, __str, strlen (__str), \ |
| __dst_cnt)); \ |
| \ |
| __result = _dl_dst_substitute (l, __str, __newp); \ |
| \ |
| if (*__result == '\0') \ |
| { \ |
| /* The replacement for the DST is not known. We can't \ |
| processed. */ \ |
| if (fatal) \ |
| _dl_signal_error (0, __str, NULL, N_("\ |
| empty dynamic string token substitution")); \ |
| else \ |
| { \ |
| /* This is for DT_AUXILIARY. */ \ |
| if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS)) \ |
| _dl_debug_printf (N_("\ |
| cannot load auxiliary `%s' because of empty dynamic string token " \ |
| "substitution\n"), __str); \ |
| continue; \ |
| } \ |
| } \ |
| } \ |
| \ |
| __result; }) |
| |
| static void |
| preload (struct list *known, unsigned int *nlist, struct link_map *map) |
| { |
| known[*nlist].done = 0; |
| known[*nlist].map = map; |
| known[*nlist].next = &known[*nlist + 1]; |
| |
| ++*nlist; |
| /* We use `l_reserved' as a mark bit to detect objects we have |
| already put in the search list and avoid adding duplicate |
| elements later in the list. */ |
| map->l_reserved = 1; |
| } |
| |
| void |
| _dl_map_object_deps (struct link_map *map, |
| struct link_map **preloads, unsigned int npreloads, |
| int trace_mode, int open_mode) |
| { |
| struct list *known = __alloca (sizeof *known * (1 + npreloads + 1)); |
| struct list *runp, *tail; |
| unsigned int nlist, i; |
| /* Object name. */ |
| const char *name; |
| int errno_saved; |
| int errno_reason; |
| struct dl_exception exception; |
| |
| /* No loaded object so far. */ |
| nlist = 0; |
| |
| /* First load MAP itself. */ |
| preload (known, &nlist, map); |
| |
| /* Add the preloaded items after MAP but before any of its dependencies. */ |
| for (i = 0; i < npreloads; ++i) |
| preload (known, &nlist, preloads[i]); |
| |
| /* Terminate the lists. */ |
| known[nlist - 1].next = NULL; |
| |
| /* Pointer to last unique object. */ |
| tail = &known[nlist - 1]; |
| |
| /* No alloca'd space yet. */ |
| struct link_map **needed_space = NULL; |
| size_t needed_space_bytes = 0; |
| |
| /* Process each element of the search list, loading each of its |
| auxiliary objects and immediate dependencies. Auxiliary objects |
| will be added in the list before the object itself and |
| dependencies will be appended to the list as we step through it. |
| This produces a flat, ordered list that represents a |
| breadth-first search of the dependency tree. |
| |
| The whole process is complicated by the fact that we better |
| should use alloca for the temporary list elements. But using |
| alloca means we cannot use recursive function calls. */ |
| errno_saved = errno; |
| errno_reason = 0; |
| errno = 0; |
| name = NULL; |
| for (runp = known; runp; ) |
| { |
| struct link_map *l = runp->map; |
| struct link_map **needed = NULL; |
| unsigned int nneeded = 0; |
| |
| /* Unless otherwise stated, this object is handled. */ |
| runp->done = 1; |
| |
| /* Allocate a temporary record to contain the references to the |
| dependencies of this object. */ |
| if (l->l_searchlist.r_list == NULL && l->l_initfini == NULL |
| && l != map && l->l_ldnum > 0) |
| { |
| size_t new_size = l->l_ldnum * sizeof (struct link_map *); |
| |
| if (new_size > needed_space_bytes) |
| needed_space |
| = extend_alloca (needed_space, needed_space_bytes, new_size); |
| |
| needed = needed_space; |
| } |
| |
| if (l->l_info[DT_NEEDED] || l->l_info[AUXTAG] || l->l_info[FILTERTAG]) |
| { |
| const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]); |
| struct openaux_args args; |
| struct list *orig; |
| const ElfW(Dyn) *d; |
| |
| args.strtab = strtab; |
| args.map = l; |
| args.trace_mode = trace_mode; |
| args.open_mode = open_mode; |
| orig = runp; |
| |
| for (d = l->l_ld; d->d_tag != DT_NULL; ++d) |
| if (__builtin_expect (d->d_tag, DT_NEEDED) == DT_NEEDED) |
| { |
| /* Map in the needed object. */ |
| struct link_map *dep; |
| |
| /* Recognize DSTs. */ |
| name = expand_dst (l, strtab + d->d_un.d_val, 0); |
| /* Store the tag in the argument structure. */ |
| args.name = name; |
| |
| int err = _dl_catch_exception (&exception, openaux, &args); |
| if (__glibc_unlikely (exception.errstring != NULL)) |
| { |
| if (err) |
| errno_reason = err; |
| else |
| errno_reason = -1; |
| goto out; |
| } |
| else |
| dep = args.aux; |
| |
| if (! dep->l_reserved) |
| { |
| /* Allocate new entry. */ |
| struct list *newp; |
| |
| newp = alloca (sizeof (struct list)); |
| |
| /* Append DEP to the list. */ |
| newp->map = dep; |
| newp->done = 0; |
| newp->next = NULL; |
| tail->next = newp; |
| tail = newp; |
| ++nlist; |
| /* Set the mark bit that says it's already in the list. */ |
| dep->l_reserved = 1; |
| } |
| |
| /* Remember this dependency. */ |
| if (needed != NULL) |
| needed[nneeded++] = dep; |
| } |
| else if (d->d_tag == DT_AUXILIARY || d->d_tag == DT_FILTER) |
| { |
| struct list *newp; |
| |
| /* Recognize DSTs. */ |
| name = expand_dst (l, strtab + d->d_un.d_val, |
| d->d_tag == DT_AUXILIARY); |
| /* Store the tag in the argument structure. */ |
| args.name = name; |
| |
| /* Say that we are about to load an auxiliary library. */ |
| if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_LIBS, |
| 0)) |
| _dl_debug_printf ("load auxiliary object=%s" |
| " requested by file=%s\n", |
| name, |
| DSO_FILENAME (l->l_name)); |
| |
| /* We must be prepared that the addressed shared |
| object is not available. For filter objects the dependency |
| must be available. */ |
| int err = _dl_catch_exception (&exception, openaux, &args); |
| if (__glibc_unlikely (exception.errstring != NULL)) |
| { |
| if (d->d_tag == DT_AUXILIARY) |
| { |
| /* We are not interested in the error message. */ |
| _dl_exception_free (&exception); |
| /* Simply ignore this error and continue the work. */ |
| continue; |
| } |
| else |
| { |
| if (err) |
| errno_reason = err; |
| else |
| errno_reason = -1; |
| goto out; |
| } |
| } |
| |
| /* The auxiliary object is actually available. |
| Incorporate the map in all the lists. */ |
| |
| /* Allocate new entry. This always has to be done. */ |
| newp = alloca (sizeof (struct list)); |
| |
| /* We want to insert the new map before the current one, |
| but we have no back links. So we copy the contents of |
| the current entry over. Note that ORIG and NEWP now |
| have switched their meanings. */ |
| memcpy (newp, orig, sizeof (*newp)); |
| |
| /* Initialize new entry. */ |
| orig->done = 0; |
| orig->map = args.aux; |
| |
| /* Remember this dependency. */ |
| if (needed != NULL) |
| needed[nneeded++] = args.aux; |
| |
| /* We must handle two situations here: the map is new, |
| so we must add it in all three lists. If the map |
| is already known, we have two further possibilities: |
| - if the object is before the current map in the |
| search list, we do nothing. It is already found |
| early |
| - if the object is after the current one, we must |
| move it just before the current map to make sure |
| the symbols are found early enough |
| */ |
| if (args.aux->l_reserved) |
| { |
| /* The object is already somewhere in the list. |
| Locate it first. */ |
| struct list *late; |
| |
| /* This object is already in the search list we |
| are building. Don't add a duplicate pointer. |
| Just added by _dl_map_object. */ |
| for (late = newp; late->next != NULL; late = late->next) |
| if (late->next->map == args.aux) |
| break; |
| |
| if (late->next != NULL) |
| { |
| /* The object is somewhere behind the current |
| position in the search path. We have to |
| move it to this earlier position. */ |
| orig->next = newp; |
| |
| /* Now remove the later entry from the list |
| and adjust the tail pointer. */ |
| if (tail == late->next) |
| tail = late; |
| late->next = late->next->next; |
| |
| /* We must move the object earlier in the chain. */ |
| if (args.aux->l_prev != NULL) |
| args.aux->l_prev->l_next = args.aux->l_next; |
| if (args.aux->l_next != NULL) |
| args.aux->l_next->l_prev = args.aux->l_prev; |
| |
| args.aux->l_prev = newp->map->l_prev; |
| newp->map->l_prev = args.aux; |
| if (args.aux->l_prev != NULL) |
| args.aux->l_prev->l_next = args.aux; |
| args.aux->l_next = newp->map; |
| } |
| else |
| { |
| /* The object must be somewhere earlier in the |
| list. Undo to the current list element what |
| we did above. */ |
| memcpy (orig, newp, sizeof (*newp)); |
| continue; |
| } |
| } |
| else |
| { |
| /* This is easy. We just add the symbol right here. */ |
| orig->next = newp; |
| ++nlist; |
| /* Set the mark bit that says it's already in the list. */ |
| args.aux->l_reserved = 1; |
| |
| /* The only problem is that in the double linked |
| list of all objects we don't have this new |
| object at the correct place. Correct this here. */ |
| if (args.aux->l_prev) |
| args.aux->l_prev->l_next = args.aux->l_next; |
| if (args.aux->l_next) |
| args.aux->l_next->l_prev = args.aux->l_prev; |
| |
| args.aux->l_prev = newp->map->l_prev; |
| newp->map->l_prev = args.aux; |
| if (args.aux->l_prev != NULL) |
| args.aux->l_prev->l_next = args.aux; |
| args.aux->l_next = newp->map; |
| } |
| |
| /* Move the tail pointer if necessary. */ |
| if (orig == tail) |
| tail = newp; |
| |
| /* Move on the insert point. */ |
| orig = newp; |
| } |
| } |
| |
| /* Terminate the list of dependencies and store the array address. */ |
| if (needed != NULL) |
| { |
| needed[nneeded++] = NULL; |
| |
| struct link_map **l_initfini = (struct link_map **) |
| malloc ((2 * nneeded + 1) * sizeof needed[0]); |
| if (l_initfini == NULL) |
| _dl_signal_error (ENOMEM, map->l_name, NULL, |
| N_("cannot allocate dependency list")); |
| l_initfini[0] = l; |
| memcpy (&l_initfini[1], needed, nneeded * sizeof needed[0]); |
| memcpy (&l_initfini[nneeded + 1], l_initfini, |
| nneeded * sizeof needed[0]); |
| atomic_write_barrier (); |
| l->l_initfini = l_initfini; |
| l->l_free_initfini = 1; |
| } |
| |
| /* If we have no auxiliary objects just go on to the next map. */ |
| if (runp->done) |
| do |
| runp = runp->next; |
| while (runp != NULL && runp->done); |
| } |
| |
| out: |
| if (errno == 0 && errno_saved != 0) |
| __set_errno (errno_saved); |
| |
| struct link_map **old_l_initfini = NULL; |
| if (map->l_initfini != NULL && map->l_type == lt_loaded) |
| { |
| /* This object was previously loaded as a dependency and we have |
| a separate l_initfini list. We don't need it anymore. */ |
| assert (map->l_searchlist.r_list == NULL); |
| old_l_initfini = map->l_initfini; |
| } |
| |
| /* Store the search list we built in the object. It will be used for |
| searches in the scope of this object. */ |
| struct link_map **l_initfini = |
| (struct link_map **) malloc ((2 * nlist + 1) |
| * sizeof (struct link_map *)); |
| if (l_initfini == NULL) |
| _dl_signal_error (ENOMEM, map->l_name, NULL, |
| N_("cannot allocate symbol search list")); |
| |
| |
| map->l_searchlist.r_list = &l_initfini[nlist + 1]; |
| map->l_searchlist.r_nlist = nlist; |
| |
| for (nlist = 0, runp = known; runp; runp = runp->next) |
| { |
| if (__builtin_expect (trace_mode, 0) && runp->map->l_faked) |
| /* This can happen when we trace the loading. */ |
| --map->l_searchlist.r_nlist; |
| else |
| map->l_searchlist.r_list[nlist++] = runp->map; |
| |
| /* Now clear all the mark bits we set in the objects on the search list |
| to avoid duplicates, so the next call starts fresh. */ |
| runp->map->l_reserved = 0; |
| } |
| |
| if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK, 0) != 0 |
| && map == GL(dl_ns)[LM_ID_BASE]._ns_loaded) |
| { |
| /* If we are to compute conflicts, we have to build local scope |
| for each library, not just the ultimate loader. */ |
| for (i = 0; i < nlist; ++i) |
| { |
| struct link_map *l = map->l_searchlist.r_list[i]; |
| unsigned int j, cnt; |
| |
| /* The local scope has been already computed. */ |
| if (l == map |
| || (l->l_local_scope[0] |
| && l->l_local_scope[0]->r_nlist) != 0) |
| continue; |
| |
| if (l->l_info[AUXTAG] || l->l_info[FILTERTAG]) |
| { |
| /* As current DT_AUXILIARY/DT_FILTER implementation needs to be |
| rewritten, no need to bother with prelinking the old |
| implementation. */ |
| _dl_signal_error (EINVAL, l->l_name, NULL, N_("\ |
| Filters not supported with LD_TRACE_PRELINKING")); |
| } |
| |
| cnt = _dl_build_local_scope (l_initfini, l); |
| assert (cnt <= nlist); |
| for (j = 0; j < cnt; j++) |
| { |
| l_initfini[j]->l_reserved = 0; |
| if (j && __builtin_expect (l_initfini[j]->l_info[DT_SYMBOLIC] |
| != NULL, 0)) |
| l->l_symbolic_in_local_scope = true; |
| } |
| |
| l->l_local_scope[0] = |
| (struct r_scope_elem *) malloc (sizeof (struct r_scope_elem) |
| + (cnt |
| * sizeof (struct link_map *))); |
| if (l->l_local_scope[0] == NULL) |
| _dl_signal_error (ENOMEM, map->l_name, NULL, |
| N_("cannot allocate symbol search list")); |
| l->l_local_scope[0]->r_nlist = cnt; |
| l->l_local_scope[0]->r_list = |
| (struct link_map **) (l->l_local_scope[0] + 1); |
| memcpy (l->l_local_scope[0]->r_list, l_initfini, |
| cnt * sizeof (struct link_map *)); |
| } |
| } |
| |
| /* Maybe we can remove some relocation dependencies now. */ |
| assert (map->l_searchlist.r_list[0] == map); |
| struct link_map_reldeps *l_reldeps = NULL; |
| if (map->l_reldeps != NULL) |
| { |
| for (i = 1; i < nlist; ++i) |
| map->l_searchlist.r_list[i]->l_reserved = 1; |
| |
| struct link_map **list = &map->l_reldeps->list[0]; |
| for (i = 0; i < map->l_reldeps->act; ++i) |
| if (list[i]->l_reserved) |
| { |
| /* Need to allocate new array of relocation dependencies. */ |
| l_reldeps = malloc (sizeof (*l_reldeps) |
| + map->l_reldepsmax |
| * sizeof (struct link_map *)); |
| if (l_reldeps == NULL) |
| /* Bad luck, keep the reldeps duplicated between |
| map->l_reldeps->list and map->l_initfini lists. */ |
| ; |
| else |
| { |
| unsigned int j = i; |
| memcpy (&l_reldeps->list[0], &list[0], |
| i * sizeof (struct link_map *)); |
| for (i = i + 1; i < map->l_reldeps->act; ++i) |
| if (!list[i]->l_reserved) |
| l_reldeps->list[j++] = list[i]; |
| l_reldeps->act = j; |
| } |
| } |
| |
| for (i = 1; i < nlist; ++i) |
| map->l_searchlist.r_list[i]->l_reserved = 0; |
| } |
| |
| /* Sort the initializer list to take dependencies into account. The binary |
| itself will always be initialize last. */ |
| memcpy (l_initfini, map->l_searchlist.r_list, |
| nlist * sizeof (struct link_map *)); |
| /* We can skip looking for the binary itself which is at the front of |
| the search list. */ |
| _dl_sort_maps (&l_initfini[1], nlist - 1, NULL, false); |
| |
| /* Terminate the list of dependencies. */ |
| l_initfini[nlist] = NULL; |
| atomic_write_barrier (); |
| map->l_initfini = l_initfini; |
| map->l_free_initfini = 1; |
| if (l_reldeps != NULL) |
| { |
| atomic_write_barrier (); |
| void *old_l_reldeps = map->l_reldeps; |
| map->l_reldeps = l_reldeps; |
| _dl_scope_free (old_l_reldeps); |
| } |
| if (old_l_initfini != NULL) |
| _dl_scope_free (old_l_initfini); |
| |
| if (errno_reason) |
| _dl_signal_exception (errno_reason == -1 ? 0 : errno_reason, |
| &exception, NULL); |
| } |
