/* Look up a symbol in the loaded objects.
- Copyright (C) 1995-2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 1995-2022 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
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. */
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <libintl.h>
#include <string.h>
#include <unistd.h>
#include <ldsodefs.h>
-#include "dl-hash.h"
+#include <dl-hash.h>
#include <dl-machine.h>
-#include <bits/libc-lock.h>
+#include <dl-protected.h>
+#include <sysdep-cancel.h>
+#include <libc-lock.h>
#include <tls.h>
+#include <atomic.h>
+#include <elf_machine_sym_no_match.h>
#include <assert.h>
#define VERSTAG(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag))
-/* We need this string more than once. */
-static const char undefined_msg[] = "undefined symbol: ";
-
-
struct sym_val
{
const ElfW(Sym) *s;
};
-#define make_string(string, rest...) \
- ({ \
- const char *all[] = { string, ## rest }; \
- size_t len, cnt; \
- char *result, *cp; \
- \
- len = 1; \
- for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \
- len += strlen (all[cnt]); \
- \
- cp = result = alloca (len); \
- for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \
- cp = __stpcpy (cp, all[cnt]); \
- \
- result; \
- })
-
/* Statistics function. */
#ifdef SHARED
# define bump_num_relocations() ++GL(dl_num_relocations)
# define bump_num_relocations() ((void) 0)
#endif
+/* Utility function for do_lookup_x. The caller is called with undef_name,
+ ref, version, flags and type_class, and those are passed as the first
+ five arguments. The caller then computes sym, symidx, strtab, and map
+ and passes them as the next four arguments. Lastly the caller passes in
+ versioned_sym and num_versions which are modified by check_match during
+ the checking process. */
+static const ElfW(Sym) *
+check_match (const char *const undef_name,
+ const ElfW(Sym) *const ref,
+ const struct r_found_version *const version,
+ const int flags,
+ const int type_class,
+ const ElfW(Sym) *const sym,
+ const Elf_Symndx symidx,
+ const char *const strtab,
+ const struct link_map *const map,
+ const ElfW(Sym) **const versioned_sym,
+ int *const num_versions)
+{
+ unsigned int stt = ELFW(ST_TYPE) (sym->st_info);
+ assert (ELF_RTYPE_CLASS_PLT == 1);
+ if (__glibc_unlikely ((sym->st_value == 0 /* No value. */
+ && sym->st_shndx != SHN_ABS
+ && stt != STT_TLS)
+ || elf_machine_sym_no_match (sym)
+ || (type_class & (sym->st_shndx == SHN_UNDEF))))
+ return NULL;
+
+ /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC,
+ STT_COMMON, STT_TLS, and STT_GNU_IFUNC since these are no
+ code/data definitions. */
+#define ALLOWED_STT \
+ ((1 << STT_NOTYPE) | (1 << STT_OBJECT) | (1 << STT_FUNC) \
+ | (1 << STT_COMMON) | (1 << STT_TLS) | (1 << STT_GNU_IFUNC))
+ if (__glibc_unlikely (((1 << stt) & ALLOWED_STT) == 0))
+ return NULL;
+
+ if (sym != ref && strcmp (strtab + sym->st_name, undef_name))
+ /* Not the symbol we are looking for. */
+ return NULL;
+
+ const ElfW(Half) *verstab = map->l_versyms;
+ if (version != NULL)
+ {
+ if (__glibc_unlikely (verstab == NULL))
+ {
+ /* We need a versioned symbol but haven't found any. If
+ this is the object which is referenced in the verneed
+ entry it is a bug in the library since a symbol must
+ not simply disappear.
+
+ It would also be a bug in the object since it means that
+ the list of required versions is incomplete and so the
+ tests in dl-version.c haven't found a problem.*/
+ assert (version->filename == NULL
+ || ! _dl_name_match_p (version->filename, map));
+
+ /* Otherwise we accept the symbol. */
+ }
+ else
+ {
+ /* We can match the version information or use the
+ default one if it is not hidden. */
+ ElfW(Half) ndx = verstab[symidx] & 0x7fff;
+ if ((map->l_versions[ndx].hash != version->hash
+ || strcmp (map->l_versions[ndx].name, version->name))
+ && (version->hidden || map->l_versions[ndx].hash
+ || (verstab[symidx] & 0x8000)))
+ /* It's not the version we want. */
+ return NULL;
+ }
+ }
+ else
+ {
+ /* No specific version is selected. There are two ways we
+ can got here:
+
+ - a binary which does not include versioning information
+ is loaded
-/* The actual lookup code. */
-#include "do-lookup.h"
+ - dlsym() instead of dlvsym() is used to get a symbol which
+ might exist in more than one form
+
+ If the library does not provide symbol version information
+ there is no problem at all: we simply use the symbol if it
+ is defined.
+
+ These two lookups need to be handled differently if the
+ library defines versions. In the case of the old
+ unversioned application the oldest (default) version
+ should be used. In case of a dlsym() call the latest and
+ public interface should be returned. */
+ if (verstab != NULL)
+ {
+ if ((verstab[symidx] & 0x7fff)
+ >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3))
+ {
+ /* Don't accept hidden symbols. */
+ if ((verstab[symidx] & 0x8000) == 0
+ && (*num_versions)++ == 0)
+ /* No version so far. */
+ *versioned_sym = sym;
+
+ return NULL;
+ }
+ }
+ }
+
+ /* There cannot be another entry for this symbol so stop here. */
+ return sym;
+}
+
+/* Utility function for do_lookup_unique. Add a symbol to TABLE. */
+static void
+enter_unique_sym (struct unique_sym *table, size_t size,
+ unsigned int hash, const char *name,
+ const ElfW(Sym) *sym, const struct link_map *map)
+{
+ size_t idx = hash % size;
+ size_t hash2 = 1 + hash % (size - 2);
+ while (table[idx].name != NULL)
+ {
+ idx += hash2;
+ if (idx >= size)
+ idx -= size;
+ }
+
+ table[idx].hashval = hash;
+ table[idx].name = name;
+ table[idx].sym = sym;
+ table[idx].map = map;
+}
+
+/* Mark MAP as NODELETE according to the lookup mode in FLAGS. During
+ initial relocation, NODELETE state is pending only. */
+static void
+mark_nodelete (struct link_map *map, int flags)
+{
+ if (flags & DL_LOOKUP_FOR_RELOCATE)
+ map->l_nodelete_pending = true;
+ else
+ map->l_nodelete_active = true;
+}
+
+/* Return true if MAP is marked as NODELETE according to the lookup
+ mode in FLAGS> */
+static bool
+is_nodelete (struct link_map *map, int flags)
+{
+ /* Non-pending NODELETE always counts. Pending NODELETE only counts
+ during initial relocation processing. */
+ return map->l_nodelete_active
+ || ((flags & DL_LOOKUP_FOR_RELOCATE) && map->l_nodelete_pending);
+}
+
+/* Utility function for do_lookup_x. Lookup an STB_GNU_UNIQUE symbol
+ in the unique symbol table, creating a new entry if necessary.
+ Return the matching symbol in RESULT. */
+static void
+do_lookup_unique (const char *undef_name, unsigned int new_hash,
+ struct link_map *map, struct sym_val *result,
+ int type_class, const ElfW(Sym) *sym, const char *strtab,
+ const ElfW(Sym) *ref, const struct link_map *undef_map,
+ int flags)
+{
+ /* We have to determine whether we already found a symbol with this
+ name before. If not then we have to add it to the search table.
+ If we already found a definition we have to use it. */
+
+ struct unique_sym_table *tab
+ = &GL(dl_ns)[map->l_ns]._ns_unique_sym_table;
+
+ __rtld_lock_lock_recursive (tab->lock);
+
+ struct unique_sym *entries = tab->entries;
+ size_t size = tab->size;
+ if (entries != NULL)
+ {
+ size_t idx = new_hash % size;
+ size_t hash2 = 1 + new_hash % (size - 2);
+ while (1)
+ {
+ if (entries[idx].hashval == new_hash
+ && strcmp (entries[idx].name, undef_name) == 0)
+ {
+ if ((type_class & ELF_RTYPE_CLASS_COPY) != 0)
+ {
+ /* We possibly have to initialize the central
+ copy from the copy addressed through the
+ relocation. */
+ result->s = sym;
+ result->m = map;
+ }
+ else
+ {
+ result->s = entries[idx].sym;
+ result->m = (struct link_map *) entries[idx].map;
+ }
+ __rtld_lock_unlock_recursive (tab->lock);
+ return;
+ }
+
+ if (entries[idx].name == NULL)
+ break;
+
+ idx += hash2;
+ if (idx >= size)
+ idx -= size;
+ }
+
+ if (size * 3 <= tab->n_elements * 4)
+ {
+ /* Expand the table. */
+#ifdef RTLD_CHECK_FOREIGN_CALL
+ /* This must not happen during runtime relocations. */
+ assert (!RTLD_CHECK_FOREIGN_CALL);
+#endif
+ size_t newsize = _dl_higher_prime_number (size + 1);
+ struct unique_sym *newentries
+ = calloc (sizeof (struct unique_sym), newsize);
+ if (newentries == NULL)
+ {
+ nomem:
+ __rtld_lock_unlock_recursive (tab->lock);
+ _dl_fatal_printf ("out of memory\n");
+ }
+
+ for (idx = 0; idx < size; ++idx)
+ if (entries[idx].name != NULL)
+ enter_unique_sym (newentries, newsize, entries[idx].hashval,
+ entries[idx].name, entries[idx].sym,
+ entries[idx].map);
+
+ tab->free (entries);
+ tab->size = newsize;
+ size = newsize;
+ entries = tab->entries = newentries;
+ tab->free = __rtld_free;
+ }
+ }
+ else
+ {
+#ifdef RTLD_CHECK_FOREIGN_CALL
+ /* This must not happen during runtime relocations. */
+ assert (!RTLD_CHECK_FOREIGN_CALL);
+#endif
+
+#define INITIAL_NUNIQUE_SYM_TABLE 31
+ size = INITIAL_NUNIQUE_SYM_TABLE;
+ entries = calloc (sizeof (struct unique_sym), size);
+ if (entries == NULL)
+ goto nomem;
+
+ tab->entries = entries;
+ tab->size = size;
+ tab->free = __rtld_free;
+ }
+
+ if ((type_class & ELF_RTYPE_CLASS_COPY) != 0)
+ enter_unique_sym (entries, size, new_hash, strtab + sym->st_name, ref,
+ undef_map);
+ else
+ {
+ enter_unique_sym (entries, size,
+ new_hash, strtab + sym->st_name, sym, map);
+
+ if (map->l_type == lt_loaded && !is_nodelete (map, flags))
+ {
+ /* Make sure we don't unload this object by
+ setting the appropriate flag. */
+ if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS))
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to unique symbol\n",
+ map->l_name, map->l_ns);
+ mark_nodelete (map, flags);
+ }
+ }
+ ++tab->n_elements;
+
+ __rtld_lock_unlock_recursive (tab->lock);
+
+ result->s = sym;
+ result->m = (struct link_map *) map;
+}
+
+/* Inner part of the lookup functions. We return a value > 0 if we
+ found the symbol, the value 0 if nothing is found and < 0 if
+ something bad happened. */
+static int
+__attribute_noinline__
+do_lookup_x (const char *undef_name, unsigned int new_hash,
+ unsigned long int *old_hash, const ElfW(Sym) *ref,
+ struct sym_val *result, struct r_scope_elem *scope, size_t i,
+ const struct r_found_version *const version, int flags,
+ struct link_map *skip, int type_class, struct link_map *undef_map)
+{
+ size_t n = scope->r_nlist;
+ /* Make sure we read the value before proceeding. Otherwise we
+ might use r_list pointing to the initial scope and r_nlist being
+ the value after a resize. That is the only path in dl-open.c not
+ protected by GSCOPE. A read barrier here might be to expensive. */
+ __asm volatile ("" : "+r" (n), "+m" (scope->r_list));
+ struct link_map **list = scope->r_list;
+
+ do
+ {
+ const struct link_map *map = list[i]->l_real;
+
+ /* Here come the extra test needed for `_dl_lookup_symbol_skip'. */
+ if (map == skip)
+ continue;
+
+ /* Don't search the executable when resolving a copy reloc. */
+ if ((type_class & ELF_RTYPE_CLASS_COPY) && map->l_type == lt_executable)
+ continue;
+
+ /* Do not look into objects which are going to be removed. */
+ if (map->l_removed)
+ continue;
+
+ /* Print some debugging info if wanted. */
+ if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SYMBOLS))
+ _dl_debug_printf ("symbol=%s; lookup in file=%s [%lu]\n",
+ undef_name, DSO_FILENAME (map->l_name),
+ map->l_ns);
+
+ /* If the hash table is empty there is nothing to do here. */
+ if (map->l_nbuckets == 0)
+ continue;
+
+ Elf_Symndx symidx;
+ int num_versions = 0;
+ const ElfW(Sym) *versioned_sym = NULL;
+
+ /* The tables for this map. */
+ const ElfW(Sym) *symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
+ const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
+
+ const ElfW(Sym) *sym;
+ const ElfW(Addr) *bitmask = map->l_gnu_bitmask;
+ if (__glibc_likely (bitmask != NULL))
+ {
+ ElfW(Addr) bitmask_word
+ = bitmask[(new_hash / __ELF_NATIVE_CLASS)
+ & map->l_gnu_bitmask_idxbits];
+
+ unsigned int hashbit1 = new_hash & (__ELF_NATIVE_CLASS - 1);
+ unsigned int hashbit2 = ((new_hash >> map->l_gnu_shift)
+ & (__ELF_NATIVE_CLASS - 1));
+
+ if (__glibc_unlikely ((bitmask_word >> hashbit1)
+ & (bitmask_word >> hashbit2) & 1))
+ {
+ Elf32_Word bucket = map->l_gnu_buckets[new_hash
+ % map->l_nbuckets];
+ if (bucket != 0)
+ {
+ const Elf32_Word *hasharr = &map->l_gnu_chain_zero[bucket];
+
+ do
+ if (((*hasharr ^ new_hash) >> 1) == 0)
+ {
+ symidx = ELF_MACHINE_HASH_SYMIDX (map, hasharr);
+ sym = check_match (undef_name, ref, version, flags,
+ type_class, &symtab[symidx], symidx,
+ strtab, map, &versioned_sym,
+ &num_versions);
+ if (sym != NULL)
+ goto found_it;
+ }
+ while ((*hasharr++ & 1u) == 0);
+ }
+ }
+ /* No symbol found. */
+ symidx = SHN_UNDEF;
+ }
+ else
+ {
+ if (*old_hash == 0xffffffff)
+ *old_hash = _dl_elf_hash (undef_name);
+
+ /* Use the old SysV-style hash table. Search the appropriate
+ hash bucket in this object's symbol table for a definition
+ for the same symbol name. */
+ for (symidx = map->l_buckets[*old_hash % map->l_nbuckets];
+ symidx != STN_UNDEF;
+ symidx = map->l_chain[symidx])
+ {
+ sym = check_match (undef_name, ref, version, flags,
+ type_class, &symtab[symidx], symidx,
+ strtab, map, &versioned_sym,
+ &num_versions);
+ if (sym != NULL)
+ goto found_it;
+ }
+ }
+
+ /* If we have seen exactly one versioned symbol while we are
+ looking for an unversioned symbol and the version is not the
+ default version we still accept this symbol since there are
+ no possible ambiguities. */
+ sym = num_versions == 1 ? versioned_sym : NULL;
+
+ if (sym != NULL)
+ {
+ found_it:
+ /* When UNDEF_MAP is NULL, which indicates we are called from
+ do_lookup_x on relocation against protected data, we skip
+ the data definion in the executable from copy reloc. */
+ if (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
+ && undef_map == NULL
+ && map->l_type == lt_executable
+ && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA)
+ {
+ const ElfW(Sym) *s;
+ unsigned int i;
+
+#if ! ELF_MACHINE_NO_RELA
+ if (map->l_info[DT_RELA] != NULL
+ && map->l_info[DT_RELASZ] != NULL
+ && map->l_info[DT_RELASZ]->d_un.d_val != 0)
+ {
+ const ElfW(Rela) *rela
+ = (const ElfW(Rela) *) D_PTR (map, l_info[DT_RELA]);
+ unsigned int rela_count
+ = map->l_info[DT_RELASZ]->d_un.d_val / sizeof (*rela);
+
+ for (i = 0; i < rela_count; i++, rela++)
+ if (elf_machine_type_class (ELFW(R_TYPE) (rela->r_info))
+ == ELF_RTYPE_CLASS_COPY)
+ {
+ s = &symtab[ELFW(R_SYM) (rela->r_info)];
+ if (!strcmp (strtab + s->st_name, undef_name))
+ goto skip;
+ }
+ }
+#endif
+#if ! ELF_MACHINE_NO_REL
+ if (map->l_info[DT_REL] != NULL
+ && map->l_info[DT_RELSZ] != NULL
+ && map->l_info[DT_RELSZ]->d_un.d_val != 0)
+ {
+ const ElfW(Rel) *rel
+ = (const ElfW(Rel) *) D_PTR (map, l_info[DT_REL]);
+ unsigned int rel_count
+ = map->l_info[DT_RELSZ]->d_un.d_val / sizeof (*rel);
+
+ for (i = 0; i < rel_count; i++, rel++)
+ if (elf_machine_type_class (ELFW(R_TYPE) (rel->r_info))
+ == ELF_RTYPE_CLASS_COPY)
+ {
+ s = &symtab[ELFW(R_SYM) (rel->r_info)];
+ if (!strcmp (strtab + s->st_name, undef_name))
+ goto skip;
+ }
+ }
+#endif
+ }
+
+ /* Hidden and internal symbols are local, ignore them. */
+ if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym)))
+ goto skip;
+
+ if (ELFW(ST_VISIBILITY) (sym->st_other) == STV_PROTECTED)
+ _dl_check_protected_symbol (undef_name, undef_map, ref, map,
+ type_class);
+
+ switch (ELFW(ST_BIND) (sym->st_info))
+ {
+ case STB_WEAK:
+ /* Weak definition. Use this value if we don't find another. */
+ if (__glibc_unlikely (GLRO(dl_dynamic_weak)))
+ {
+ if (! result->s)
+ {
+ result->s = sym;
+ result->m = (struct link_map *) map;
+ }
+ break;
+ }
+ /* FALLTHROUGH */
+ case STB_GLOBAL:
+ /* Global definition. Just what we need. */
+ result->s = sym;
+ result->m = (struct link_map *) map;
+ return 1;
+
+ case STB_GNU_UNIQUE:;
+ do_lookup_unique (undef_name, new_hash, (struct link_map *) map,
+ result, type_class, sym, strtab, ref,
+ undef_map, flags);
+ return 1;
+
+ default:
+ /* Local symbols are ignored. */
+ break;
+ }
+ }
+
+skip:
+ ;
+ }
+ while (++i < n);
+
+ /* We have not found anything until now. */
+ return 0;
+}
+
+
+static uint32_t
+dl_new_hash (const char *s)
+{
+ uint32_t h = 5381;
+ for (unsigned char c = *s; c != '\0'; c = *++s)
+ h = h * 33 + c;
+ return h;
+}
/* Add extra dependency on MAP to UNDEF_MAP. */
static int
-internal_function
-add_dependency (struct link_map *undef_map, struct link_map *map)
+add_dependency (struct link_map *undef_map, struct link_map *map, int flags)
{
- struct link_map **list;
struct link_map *runp;
- unsigned int act;
unsigned int i;
int result = 0;
if (undef_map == map)
return 0;
- /* Make sure nobody can unload the object while we are at it. */
- __rtld_lock_lock_recursive (GL(dl_load_lock));
+ /* Avoid references to objects which cannot be unloaded anyway. We
+ do not need to record dependencies if this object goes away
+ during dlopen failure, either. IFUNC resolvers with relocation
+ dependencies may pick an dependency which can be dlclose'd, but
+ such IFUNC resolvers are undefined anyway. */
+ assert (map->l_type == lt_loaded);
+ if (is_nodelete (map, flags))
+ return 0;
- /* Don't create cross-reference between modules which are
- dynamically loaded by the same dlopen() call. */
- if (undef_map->l_opencount == 0 && map->l_opencount == 0)
- goto out;
+ struct link_map_reldeps *l_reldeps
+ = atomic_forced_read (undef_map->l_reldeps);
- /* Avoid references to objects which cannot be unloaded anyway. */
- if (map->l_type != lt_loaded
- || (map->l_flags_1 & DF_1_NODELETE) != 0)
- goto out;
-
- /* If the object with the undefined reference cannot be removed ever
- just make sure the same is true for the object which contains the
- definition. */
- if (undef_map->l_type != lt_loaded
- || (undef_map->l_flags_1 & DF_1_NODELETE) != 0)
- {
- ++map->l_opencount;
- map->l_flags |= DF_1_NODELETE;
- goto out;
- }
+ /* Make sure l_reldeps is read before l_initfini. */
+ atomic_read_barrier ();
/* Determine whether UNDEF_MAP already has a reference to MAP. First
look in the normal dependencies. */
- if (undef_map->l_searchlist.r_list != NULL)
+ struct link_map **l_initfini = atomic_forced_read (undef_map->l_initfini);
+ if (l_initfini != NULL)
{
- list = undef_map->l_initfini;
-
- for (i = 0; list[i] != NULL; ++i)
- if (list[i] == map)
- goto out;
+ for (i = 0; l_initfini[i] != NULL; ++i)
+ if (l_initfini[i] == map)
+ return 0;
}
/* No normal dependency. See whether we already had to add it
to the special list of dynamic dependencies. */
- list = undef_map->l_reldeps;
- act = undef_map->l_reldepsact;
+ unsigned int l_reldepsact = 0;
+ if (l_reldeps != NULL)
+ {
+ struct link_map **list = &l_reldeps->list[0];
+ l_reldepsact = l_reldeps->act;
+ for (i = 0; i < l_reldepsact; ++i)
+ if (list[i] == map)
+ return 0;
+ }
- for (i = 0; i < act; ++i)
- if (list[i] == map)
- goto out;
+ /* Save serial number of the target MAP. */
+ unsigned long long serial = map->l_serial;
+
+ /* Make sure nobody can unload the object while we are at it. */
+ if (__glibc_unlikely (flags & DL_LOOKUP_GSCOPE_LOCK))
+ {
+ /* We can't just call __rtld_lock_lock_recursive (GL(dl_load_lock))
+ here, that can result in ABBA deadlock. */
+ THREAD_GSCOPE_RESET_FLAG ();
+ __rtld_lock_lock_recursive (GL(dl_load_lock));
+ /* While MAP value won't change, after THREAD_GSCOPE_RESET_FLAG ()
+ it can e.g. point to unallocated memory. So avoid the optimizer
+ treating the above read from MAP->l_serial as ensurance it
+ can safely dereference it. */
+ map = atomic_forced_read (map);
+
+ /* From this point on it is unsafe to dereference MAP, until it
+ has been found in one of the lists. */
+
+ /* Redo the l_initfini check in case undef_map's l_initfini
+ changed in the mean time. */
+ if (undef_map->l_initfini != l_initfini
+ && undef_map->l_initfini != NULL)
+ {
+ l_initfini = undef_map->l_initfini;
+ for (i = 0; l_initfini[i] != NULL; ++i)
+ if (l_initfini[i] == map)
+ goto out_check;
+ }
+
+ /* Redo the l_reldeps check if undef_map's l_reldeps changed in
+ the mean time. */
+ if (undef_map->l_reldeps != NULL)
+ {
+ if (undef_map->l_reldeps != l_reldeps)
+ {
+ struct link_map **list = &undef_map->l_reldeps->list[0];
+ l_reldepsact = undef_map->l_reldeps->act;
+ for (i = 0; i < l_reldepsact; ++i)
+ if (list[i] == map)
+ goto out_check;
+ }
+ else if (undef_map->l_reldeps->act > l_reldepsact)
+ {
+ struct link_map **list
+ = &undef_map->l_reldeps->list[0];
+ i = l_reldepsact;
+ l_reldepsact = undef_map->l_reldeps->act;
+ for (; i < l_reldepsact; ++i)
+ if (list[i] == map)
+ goto out_check;
+ }
+ }
+ }
+ else
+ __rtld_lock_lock_recursive (GL(dl_load_lock));
/* The object is not yet in the dependency list. Before we add
it make sure just one more time the object we are about to
reference is still available. There is a brief period in
which the object could have been removed since we found the
definition. */
- runp = GL(dl_loaded);
+ runp = GL(dl_ns)[undef_map->l_ns]._ns_loaded;
while (runp != NULL && runp != map)
runp = runp->l_next;
if (runp != NULL)
{
- /* The object is still available. Add the reference now. */
- if (__builtin_expect (act >= undef_map->l_reldepsmax, 0))
+ /* The object is still available. */
+
+ /* MAP could have been dlclosed, freed and then some other dlopened
+ library could have the same link_map pointer. */
+ if (map->l_serial != serial)
+ goto out_check;
+
+ /* Redo the NODELETE check, as when dl_load_lock wasn't held
+ yet this could have changed. */
+ if (is_nodelete (map, flags))
+ goto out;
+
+ /* If the object with the undefined reference cannot be removed ever
+ just make sure the same is true for the object which contains the
+ definition. */
+ if (undef_map->l_type != lt_loaded || is_nodelete (map, flags))
+ {
+ if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS)
+ && !is_nodelete (map, flags))
+ {
+ if (undef_map->l_name[0] == '\0')
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to reference to main program\n",
+ map->l_name, map->l_ns);
+ else
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to reference to %s [%lu]\n",
+ map->l_name, map->l_ns,
+ undef_map->l_name, undef_map->l_ns);
+ }
+ mark_nodelete (map, flags);
+ goto out;
+ }
+
+ /* Add the reference now. */
+ if (__glibc_unlikely (l_reldepsact >= undef_map->l_reldepsmax))
{
/* Allocate more memory for the dependency list. Since this
can never happen during the startup phase we can use
`realloc'. */
- void *newp;
+ struct link_map_reldeps *newp;
+ unsigned int max
+ = undef_map->l_reldepsmax ? undef_map->l_reldepsmax * 2 : 10;
- undef_map->l_reldepsmax += 5;
- newp = realloc (undef_map->l_reldeps,
- undef_map->l_reldepsmax
- * sizeof (struct link_map *));
+#ifdef RTLD_PREPARE_FOREIGN_CALL
+ RTLD_PREPARE_FOREIGN_CALL;
+#endif
- if (__builtin_expect (newp != NULL, 1))
- undef_map->l_reldeps = (struct link_map **) newp;
+ newp = malloc (sizeof (*newp) + max * sizeof (struct link_map *));
+ if (newp == NULL)
+ {
+ /* If we didn't manage to allocate memory for the list this is
+ no fatal problem. We simply make sure the referenced object
+ cannot be unloaded. This is semantically the correct
+ behavior. */
+ if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS)
+ && !is_nodelete (map, flags))
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to memory allocation failure\n",
+ map->l_name, map->l_ns);
+ /* In case of non-lazy binding, we could actually report
+ the memory allocation error, but for now, we use the
+ conservative approximation as well. */
+ mark_nodelete (map, flags);
+ goto out;
+ }
else
- /* Correct the addition. */
- undef_map->l_reldepsmax -= 5;
+ {
+ if (l_reldepsact)
+ memcpy (&newp->list[0], &undef_map->l_reldeps->list[0],
+ l_reldepsact * sizeof (struct link_map *));
+ newp->list[l_reldepsact] = map;
+ newp->act = l_reldepsact + 1;
+ atomic_write_barrier ();
+ void *old = undef_map->l_reldeps;
+ undef_map->l_reldeps = newp;
+ undef_map->l_reldepsmax = max;
+ if (old)
+ _dl_scope_free (old);
+ }
}
-
- /* If we didn't manage to allocate memory for the list this is
- no fatal mistake. We simply increment the use counter of the
- referenced object and don't record the dependencies. This
- means this increment can never be reverted and the object
- will never be unloaded. This is semantically the correct
- behavior. */
- if (__builtin_expect (act < undef_map->l_reldepsmax, 1))
- undef_map->l_reldeps[undef_map->l_reldepsact++] = map;
-
- if (map->l_searchlist.r_list != NULL)
- /* And increment the counter in the referenced object. */
- ++map->l_opencount;
else
- /* We have to bump the counts for all dependencies since so far
- this object was only a normal or transitive dependency.
- Now it might be closed with _dl_close() directly. */
- for (list = map->l_initfini; *list != NULL; ++list)
- ++(*list)->l_opencount;
+ {
+ undef_map->l_reldeps->list[l_reldepsact] = map;
+ atomic_write_barrier ();
+ undef_map->l_reldeps->act = l_reldepsact + 1;
+ }
/* Display information if we are debugging. */
- if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
+ if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES))
_dl_debug_printf ("\
-\nfile=%s; needed by %s (relocation dependency)\n\n",
- map->l_name[0] ? map->l_name : rtld_progname,
- undef_map->l_name[0]
- ? undef_map->l_name : rtld_progname);
+\nfile=%s [%lu]; needed by %s [%lu] (relocation dependency)\n\n",
+ DSO_FILENAME (map->l_name),
+ map->l_ns,
+ DSO_FILENAME (undef_map->l_name),
+ undef_map->l_ns);
}
else
/* Whoa, that was bad luck. We have to search again. */
/* Release the lock. */
__rtld_lock_unlock_recursive (GL(dl_load_lock));
+ if (__glibc_unlikely (flags & DL_LOOKUP_GSCOPE_LOCK))
+ THREAD_GSCOPE_SET_FLAG ();
+
return result;
-}
-static void
-internal_function
-_dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
- const ElfW(Sym) **ref, struct r_scope_elem *symbol_scope[],
- struct sym_val *value,
- const struct r_found_version *version, int type_class,
- int protected);
+ out_check:
+ if (map->l_serial != serial)
+ result = -1;
+ goto out;
+}
/* Search loaded objects' symbol tables for a definition of the symbol
- UNDEF_NAME, perhaps with a requested version for the symbol. */
+ UNDEF_NAME, perhaps with a requested version for the symbol.
+
+ We must never have calls to the audit functions inside this function
+ or in any function which gets called. If this would happen the audit
+ code might create a thread which can throw off all the scope locking. */
lookup_t
-internal_function
_dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
const ElfW(Sym) **ref,
struct r_scope_elem *symbol_scope[],
const struct r_found_version *version,
int type_class, int flags, struct link_map *skip_map)
{
- const unsigned long int hash = _dl_elf_hash (undef_name);
+ const unsigned int new_hash = dl_new_hash (undef_name);
+ unsigned long int old_hash = 0xffffffff;
struct sym_val current_value = { NULL, NULL };
struct r_scope_elem **scope = symbol_scope;
bump_num_relocations ();
- /* No other flag than DL_LOOKUP_ADD_DEPENDENCY is allowed if we look
- up a versioned symbol. */
- assert (version == NULL || flags == 0 || flags == DL_LOOKUP_ADD_DEPENDENCY);
+ /* DL_LOOKUP_RETURN_NEWEST does not make sense for versioned
+ lookups. */
+ assert (version == NULL || !(flags & DL_LOOKUP_RETURN_NEWEST));
size_t i = 0;
- if (__builtin_expect (skip_map != NULL, 0))
- {
- /* Search the relevant loaded objects for a definition. */
- while ((*scope)->r_list[i] != skip_map)
- ++i;
-
- assert (i < (*scope)->r_nlist);
- }
+ if (__glibc_unlikely (skip_map != NULL))
+ /* Search the relevant loaded objects for a definition. */
+ while ((*scope)->r_list[i] != skip_map)
+ ++i;
/* Search the relevant loaded objects for a definition. */
for (size_t start = i; *scope != NULL; start = 0, ++scope)
- {
- int res = do_lookup_x (undef_name, hash, *ref, ¤t_value, *scope,
- start, version, flags, skip_map, type_class);
- if (res > 0)
- break;
+ if (do_lookup_x (undef_name, new_hash, &old_hash, *ref,
+ ¤t_value, *scope, start, version, flags,
+ skip_map, type_class, undef_map) != 0)
+ break;
- if (__builtin_expect (res, 0) < 0 && skip_map == NULL)
- {
- /* Oh, oh. The file named in the relocation entry does not
- contain the needed symbol. This code is never reached
- for unversioned lookups. */
- assert (version != NULL);
- const char *reference_name = undef_map ? undef_map->l_name : NULL;
-
- /* XXX We cannot translate the message. */
- _dl_signal_cerror (0, (reference_name[0]
- ? reference_name
- : (rtld_progname ?: "<main program>")),
- N_("relocation error"),
- make_string ("symbol ", undef_name, ", version ",
- version->name,
- " not defined in file ",
- version->filename,
- " with link time reference",
- res == -2
- ? " (no version symbols)" : ""));
- *ref = NULL;
- return 0;
- }
- }
-
- if (__builtin_expect (current_value.s == NULL, 0))
+ if (__glibc_unlikely (current_value.s == NULL))
{
if ((*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
- && skip_map == NULL)
+ && !(GLRO(dl_debug_mask) & DL_DEBUG_UNUSED))
{
/* We could find no value for a strong reference. */
const char *reference_name = undef_map ? undef_map->l_name : "";
const char *versionstr = version ? ", version " : "";
const char *versionname = (version && version->name
? version->name : "");
-
+ struct dl_exception exception;
/* XXX We cannot translate the message. */
- _dl_signal_cerror (0, (reference_name[0]
- ? reference_name
- : (rtld_progname ?: "<main program>")),
- N_("symbol lookup error"),
- make_string (undefined_msg, undef_name,
- versionstr, versionname));
+ _dl_exception_create_format
+ (&exception, DSO_FILENAME (reference_name),
+ "undefined symbol: %s%s%s",
+ undef_name, versionstr, versionname);
+ _dl_signal_cexception (0, &exception, N_("symbol lookup error"));
+ _dl_exception_free (&exception);
}
*ref = NULL;
return 0;
int protected = (*ref
&& ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED);
- if (__builtin_expect (protected != 0, 0))
+ if (__glibc_unlikely (protected != 0))
{
/* It is very tricky. We need to figure out what value to
- return for the protected symbol. */
+ return for the protected symbol. */
if (type_class == ELF_RTYPE_CLASS_PLT)
{
if (current_value.s != NULL && current_value.m != undef_map)
struct sym_val protected_value = { NULL, NULL };
for (scope = symbol_scope; *scope != NULL; i = 0, ++scope)
- if (do_lookup_x (undef_name, hash, *ref, &protected_value,
- *scope, i, version, flags, skip_map,
- ELF_RTYPE_CLASS_PLT) != 0)
+ if (do_lookup_x (undef_name, new_hash, &old_hash, *ref,
+ &protected_value, *scope, i, version, flags,
+ skip_map,
+ (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
+ && ELFW(ST_TYPE) ((*ref)->st_info) == STT_OBJECT
+ && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA)
+ ? ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
+ : ELF_RTYPE_CLASS_PLT, NULL) != 0)
break;
if (protected_value.s != NULL && protected_value.m != undef_map)
in the global scope which was dynamically loaded. In this case
we have to prevent the latter from being unloaded unless the
UNDEF_MAP object is also unloaded. */
- if (__builtin_expect (current_value.m->l_type == lt_loaded, 0)
+ if (__glibc_unlikely (current_value.m->l_type == lt_loaded)
/* Don't do this for explicit lookups as opposed to implicit
runtime lookups. */
&& (flags & DL_LOOKUP_ADD_DEPENDENCY) != 0
/* Add UNDEF_MAP to the dependencies. */
- && add_dependency (undef_map, current_value.m) < 0)
+ && add_dependency (undef_map, current_value.m, flags) < 0)
/* Something went wrong. Perhaps the object we tried to reference
was just removed. Try finding another definition. */
return _dl_lookup_symbol_x (undef_name, undef_map, ref,
- symbol_scope, version, type_class,
- flags, skip_map);
+ (flags & DL_LOOKUP_GSCOPE_LOCK)
+ ? undef_map->l_scope : symbol_scope,
+ version, type_class, flags, skip_map);
- if (__builtin_expect (GLRO(dl_debug_mask)
- & (DL_DEBUG_BINDINGS|DL_DEBUG_PRELINK), 0))
- _dl_debug_bindings (undef_name, undef_map, ref, symbol_scope,
- ¤t_value, version, type_class, protected);
+ /* The object is used. */
+ if (__glibc_unlikely (current_value.m->l_used == 0))
+ current_value.m->l_used = 1;
*ref = current_value.s;
return LOOKUP_VALUE (current_value.m);
}
-
-
-/* Cache the location of MAP's hash table. */
-
-void
-internal_function
-_dl_setup_hash (struct link_map *map)
-{
- Elf_Symndx *hash;
- Elf_Symndx nchain;
-
- if (!map->l_info[DT_HASH])
- return;
- hash = (void *) D_PTR (map, l_info[DT_HASH]);
-
- map->l_nbuckets = *hash++;
- nchain = *hash++;
- map->l_buckets = hash;
- hash += map->l_nbuckets;
- map->l_chain = hash;
-}
-
-
-static void
-internal_function
-_dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
- const ElfW(Sym) **ref, struct r_scope_elem *symbol_scope[],
- struct sym_val *value,
- const struct r_found_version *version, int type_class,
- int protected)
-{
- const char *reference_name = undef_map->l_name;
-
- if (GLRO(dl_debug_mask) & DL_DEBUG_BINDINGS)
- {
- _dl_debug_printf ("binding file %s to %s: %s symbol `%s'",
- (reference_name[0]
- ? reference_name
- : (rtld_progname ?: "<main program>")),
- value->m->l_name[0] ? value->m->l_name : rtld_progname,
- protected ? "protected" : "normal", undef_name);
- if (version)
- _dl_debug_printf_c (" [%s]\n", version->name);
- else
- _dl_debug_printf_c ("\n");
- }
-#ifdef SHARED
- if (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK)
- {
- int conflict = 0;
- struct sym_val val = { NULL, NULL };
-
- if ((GLRO(dl_trace_prelink_map) == NULL
- || GLRO(dl_trace_prelink_map) == GL(dl_loaded))
- && undef_map != GL(dl_loaded))
- {
- const unsigned long int hash = _dl_elf_hash (undef_name);
-
- do_lookup_x (undef_name, hash, *ref, &val,
- undef_map->l_local_scope[0], 0, version, 0, NULL,
- type_class);
-
- if (val.s != value->s || val.m != value->m)
- conflict = 1;
- }
-
-#ifdef USE_TLS
- if (value->s
- && (__builtin_expect (ELFW(ST_TYPE) (value->s->st_info)
- == STT_TLS, 0)))
- type_class = 4;
-#endif
-
- if (conflict
- || GLRO(dl_trace_prelink_map) == undef_map
- || GLRO(dl_trace_prelink_map) == NULL
- || type_class == 4)
- {
- _dl_printf ("%s 0x%0*Zx 0x%0*Zx -> 0x%0*Zx 0x%0*Zx ",
- conflict ? "conflict" : "lookup",
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) undef_map->l_map_start,
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (((ElfW(Addr)) *ref) - undef_map->l_map_start),
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (value->s ? value->m->l_map_start : 0),
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (value->s ? value->s->st_value : 0));
-
- if (conflict)
- _dl_printf ("x 0x%0*Zx 0x%0*Zx ",
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (val.s ? val.m->l_map_start : 0),
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (val.s ? val.s->st_value : 0));
-
- _dl_printf ("/%x %s\n", type_class, undef_name);
- }
- }
-#endif
-}
projects / thirdparty / glibc.git / blobdiff