diff options
Diffstat (limited to 'REORG.TODO/elf/dl-lookup.c')
| -rw-r--r-- | REORG.TODO/elf/dl-lookup.c | 1129 |
1 files changed, 1129 insertions, 0 deletions
diff --git a/REORG.TODO/elf/dl-lookup.c b/REORG.TODO/elf/dl-lookup.c new file mode 100644 index 0000000000..3d2369dbf2 --- /dev/null +++ b/REORG.TODO/elf/dl-lookup.c @@ -0,0 +1,1129 @@ +/* Look up a symbol in the loaded objects. + Copyright (C) 1995-2017 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 <alloca.h> +#include <libintl.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <ldsodefs.h> +#include <dl-hash.h> +#include <dl-machine.h> +#include <sysdep-cancel.h> +#include <libc-lock.h> +#include <tls.h> +#include <atomic.h> + +#include <assert.h> + +/* Return nonzero if check_match should consider SYM to fail to match a + symbol reference for some machine-specific reason. */ +#ifndef ELF_MACHINE_SYM_NO_MATCH +# define ELF_MACHINE_SYM_NO_MATCH(sym) 0 +#endif + +#define VERSTAG(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag)) + + +struct sym_val + { + const ElfW(Sym) *s; + struct link_map *m; + }; + + +#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) +#else +# 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. */ + && 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 + + - 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; +} + +/* 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, uint_fast32_t new_hash, + const 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) +{ + /* 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 = (struct link_map *) 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 = free; + } + } + else + { +#ifdef RTLD_CHECK_FOREIGN_CALL + /* This must not happen during runtime relocations. */ + assert (!RTLD_CHECK_FOREIGN_CALL); +#endif + +#ifdef SHARED + /* If tab->entries is NULL, but tab->size is not, it means + this is the second, conflict finding, lookup for + LD_TRACE_PRELINKING in _dl_debug_bindings. Don't + allocate anything and don't enter anything into the + hash table. */ + if (__glibc_unlikely (tab->size)) + { + assert (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK); + goto success; + } +#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 = 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) + /* Make sure we don't unload this object by + setting the appropriate flag. */ + ((struct link_map *) map)->l_flags_1 |= DF_1_NODELETE; + } + ++tab->n_elements; + +#ifdef SHARED + success: +#endif + __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, uint_fast32_t 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 = hasharr - map->l_gnu_chain_zero; + 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; + + 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, map, result, type_class, + sym, strtab, ref, undef_map); + return 1; + + default: + /* Local symbols are ignored. */ + break; + } + } + +skip: + /* If this current map is the one mentioned in the verneed entry + and we have not found a weak entry, it is a bug. */ + if (symidx == STN_UNDEF && version != NULL && version->filename != NULL + && __glibc_unlikely (_dl_name_match_p (version->filename, map))) + return -1; + } + while (++i < n); + + /* We have not found anything until now. */ + return 0; +} + + +static uint_fast32_t +dl_new_hash (const char *s) +{ + uint_fast32_t h = 5381; + for (unsigned char c = *s; c != '\0'; c = *++s) + h = h * 33 + c; + return h & 0xffffffff; +} + + +/* Add extra dependency on MAP to UNDEF_MAP. */ +static int +internal_function +add_dependency (struct link_map *undef_map, struct link_map *map, int flags) +{ + struct link_map *runp; + unsigned int i; + int result = 0; + + /* Avoid self-references and references to objects which cannot be + unloaded anyway. */ + if (undef_map == map) + return 0; + + /* Avoid references to objects which cannot be unloaded anyway. */ + assert (map->l_type == lt_loaded); + if ((map->l_flags_1 & DF_1_NODELETE) != 0) + return 0; + + struct link_map_reldeps *l_reldeps + = atomic_forced_read (undef_map->l_reldeps); + + /* 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. */ + struct link_map **l_initfini = atomic_forced_read (undef_map->l_initfini); + if (l_initfini != NULL) + { + 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. */ + 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; + } + + /* 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_ns)[undef_map->l_ns]._ns_loaded; + while (runp != NULL && runp != map) + runp = runp->l_next; + + if (runp != NULL) + { + /* 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 ((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_flags_1 |= DF_1_NODELETE; + 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'. */ + struct link_map_reldeps *newp; + unsigned int max + = undef_map->l_reldepsmax ? undef_map->l_reldepsmax * 2 : 10; + +#ifdef RTLD_PREPARE_FOREIGN_CALL + RTLD_PREPARE_FOREIGN_CALL; +#endif + + 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. */ + map->l_flags_1 |= DF_1_NODELETE; + goto out; + } + else + { + 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); + } + } + else + { + 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 (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES)) + _dl_debug_printf ("\ +\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. */ + result = -1; + + out: + /* 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; + + out_check: + if (map->l_serial != serial) + result = -1; + goto out; +} + +static void +internal_function +_dl_debug_bindings (const char *undef_name, struct link_map *undef_map, + const ElfW(Sym) **ref, struct sym_val *value, + const struct r_found_version *version, int type_class, + int protected); + + +/* Search loaded objects' symbol tables for a definition of 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 uint_fast32_t 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 or DL_LOOKUP_GSCOPE_LOCK + is allowed if we look up a versioned symbol. */ + assert (version == NULL + || (flags & ~(DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_GSCOPE_LOCK)) + == 0); + + size_t i = 0; + 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, new_hash, &old_hash, *ref, + ¤t_value, *scope, start, version, flags, + skip_map, type_class, undef_map); + if (res > 0) + break; + + if (__glibc_unlikely (res < 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 : ""; + + /* XXX We cannot translate the message. */ + _dl_signal_cerror (0, DSO_FILENAME (reference_name), + 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 (__glibc_unlikely (current_value.s == NULL)) + { + if ((*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK) + && !(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 : ""); + + /* XXX We cannot translate the message. */ + _dl_signal_cerror (0, DSO_FILENAME (reference_name), + N_("symbol lookup error"), + make_string ("undefined symbol: ", undef_name, + versionstr, versionname)); + } + *ref = NULL; + return 0; + } + + int protected = (*ref + && ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED); + if (__glibc_unlikely (protected != 0)) + { + /* It is very tricky. We need to figure out what value to + return for the protected symbol. */ + if (type_class == ELF_RTYPE_CLASS_PLT) + { + if (current_value.s != NULL && current_value.m != undef_map) + { + current_value.s = *ref; + current_value.m = undef_map; + } + } + else + { + struct sym_val protected_value = { NULL, NULL }; + + for (scope = symbol_scope; *scope != NULL; i = 0, ++scope) + 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) + { + current_value.s = *ref; + current_value.m = undef_map; + } + } + } + + /* We have to check whether this would bind UNDEF_MAP to an object + 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 (__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, 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, + (flags & DL_LOOKUP_GSCOPE_LOCK) + ? undef_map->l_scope : symbol_scope, + version, type_class, flags, skip_map); + + /* The object is used. */ + if (__glibc_unlikely (current_value.m->l_used == 0)) + current_value.m->l_used = 1; + + if (__glibc_unlikely (GLRO(dl_debug_mask) + & (DL_DEBUG_BINDINGS|DL_DEBUG_PRELINK))) + _dl_debug_bindings (undef_name, undef_map, ref, + ¤t_value, version, type_class, protected); + + *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; + + if (__glibc_likely (map->l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM + + DT_THISPROCNUM + DT_VERSIONTAGNUM + + DT_EXTRANUM + DT_VALNUM] != NULL)) + { + Elf32_Word *hash32 + = (void *) D_PTR (map, l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM + + DT_THISPROCNUM + DT_VERSIONTAGNUM + + DT_EXTRANUM + DT_VALNUM]); + map->l_nbuckets = *hash32++; + Elf32_Word symbias = *hash32++; + Elf32_Word bitmask_nwords = *hash32++; + /* Must be a power of two. */ + assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0); + map->l_gnu_bitmask_idxbits = bitmask_nwords - 1; + map->l_gnu_shift = *hash32++; + + map->l_gnu_bitmask = (ElfW(Addr) *) hash32; + hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords; + + map->l_gnu_buckets = hash32; + hash32 += map->l_nbuckets; + map->l_gnu_chain_zero = hash32 - symbias; + return; + } + + if (!map->l_info[DT_HASH]) + return; + hash = (void *) D_PTR (map, l_info[DT_HASH]); + + map->l_nbuckets = *hash++; + /* Skip 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 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 [%lu] to %s [%lu]: %s symbol `%s'", + DSO_FILENAME (reference_name), + undef_map->l_ns, + DSO_FILENAME (value->m->l_name), + value->m->l_ns, + 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) + { +/* ELF_RTYPE_CLASS_XXX must match RTYPE_CLASS_XXX used by prelink with + LD_TRACE_PRELINKING. */ +#define RTYPE_CLASS_VALID 8 +#define RTYPE_CLASS_PLT (8|1) +#define RTYPE_CLASS_COPY (8|2) +#define RTYPE_CLASS_TLS (8|4) +#if ELF_RTYPE_CLASS_PLT != 0 && ELF_RTYPE_CLASS_PLT != 1 +# error ELF_RTYPE_CLASS_PLT must be 0 or 1! +#endif +#if ELF_RTYPE_CLASS_COPY != 0 && ELF_RTYPE_CLASS_COPY != 2 +# error ELF_RTYPE_CLASS_COPY must be 0 or 2! +#endif + 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 uint_fast32_t new_hash = dl_new_hash (undef_name); + unsigned long int old_hash = 0xffffffff; + struct unique_sym *saved_entries + = GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries; + + GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries = NULL; + do_lookup_x (undef_name, new_hash, &old_hash, *ref, &val, + undef_map->l_local_scope[0], 0, version, 0, NULL, + type_class, undef_map); + if (val.s != value->s || val.m != value->m) + conflict = 1; + else if (__glibc_unlikely (undef_map->l_symbolic_in_local_scope) + && val.s + && __glibc_unlikely (ELFW(ST_BIND) (val.s->st_info) + == STB_GNU_UNIQUE)) + { + /* If it is STB_GNU_UNIQUE and undef_map's l_local_scope + contains any DT_SYMBOLIC libraries, unfortunately there + can be conflicts even if the above is equal. As symbol + resolution goes from the last library to the first and + if a STB_GNU_UNIQUE symbol is found in some late DT_SYMBOLIC + library, it would be the one that is looked up. */ + struct sym_val val2 = { NULL, NULL }; + size_t n; + struct r_scope_elem *scope = undef_map->l_local_scope[0]; + + for (n = 0; n < scope->r_nlist; n++) + if (scope->r_list[n] == val.m) + break; + + for (n++; n < scope->r_nlist; n++) + if (scope->r_list[n]->l_info[DT_SYMBOLIC] != NULL + && do_lookup_x (undef_name, new_hash, &old_hash, *ref, + &val2, + &scope->r_list[n]->l_symbolic_searchlist, + 0, version, 0, NULL, type_class, + undef_map) > 0) + { + conflict = 1; + val = val2; + break; + } + } + GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries = saved_entries; + } + + if (value->s) + { + /* Keep only ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY + bits since since prelink only uses them. */ + type_class &= ELF_RTYPE_CLASS_PLT | ELF_RTYPE_CLASS_COPY; + if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info) + == STT_TLS)) + /* Clear the RTYPE_CLASS_VALID bit in RTYPE_CLASS_TLS. */ + type_class = RTYPE_CLASS_TLS & ~RTYPE_CLASS_VALID; + else if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info) + == STT_GNU_IFUNC)) + /* Set the RTYPE_CLASS_VALID bit. */ + type_class |= RTYPE_CLASS_VALID; + } + + 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 +} |