/* 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_1 |= 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
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;
-
- /* As if it is opened through _dl_open. */
- ++map->l_direct_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 [%lu]; needed by %s [%lu] (relocation dependency)\n\n",
- map->l_name[0] ? map->l_name : rtld_progname,
+ DSO_FILENAME (map->l_name),
map->l_ns,
- undef_map->l_name[0]
- ? undef_map->l_name : rtld_progname,
+ DSO_FILENAME (undef_map->l_name),
undef_map->l_ns);
}
else
/* 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);
/* The object is used. */
- current_value.m->l_used = 1;
-
- 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);
+ 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_ns)[LM_ID_BASE]._ns_loaded)
- && undef_map != GL(dl_ns)[LM_ID_BASE]._ns_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