/* Look up a symbol in a shared object loaded by `dlopen'. Copyright (C) 1999-2002,2004,2006,2007,2009 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, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <assert.h> #include <stddef.h> #include <setjmp.h> #include <libintl.h> #include <dlfcn.h> #include <ldsodefs.h> #include <dl-hash.h> #include <sysdep-cancel.h> #include <dl-tls.h> #ifdef SHARED /* Systems which do not have tls_index also probably have to define DONT_USE_TLS_INDEX. */ # ifndef __TLS_GET_ADDR # define __TLS_GET_ADDR __tls_get_addr # endif /* Return the symbol address given the map of the module it is in and the symbol record. This is used in dl-sym.c. */ static void * internal_function _dl_tls_symaddr (struct link_map *map, const ElfW(Sym) *ref) { # ifndef DONT_USE_TLS_INDEX tls_index tmp = { .ti_module = map->l_tls_modid, .ti_offset = ref->st_value }; return __TLS_GET_ADDR (&tmp); # else return __TLS_GET_ADDR (map->l_tls_modid, ref->st_value); # endif } #endif struct call_dl_lookup_args { /* Arguments to do_dlsym. */ struct link_map *map; const char *name; struct r_found_version *vers; int flags; /* Return values of do_dlsym. */ lookup_t loadbase; const ElfW(Sym) **refp; }; static void call_dl_lookup (void *ptr) { struct call_dl_lookup_args *args = (struct call_dl_lookup_args *) ptr; args->map = GLRO(dl_lookup_symbol_x) (args->name, args->map, args->refp, args->map->l_scope, args->vers, 0, args->flags, NULL); } static void * internal_function do_sym (void *handle, const char *name, void *who, struct r_found_version *vers, int flags) { const ElfW(Sym) *ref = NULL; lookup_t result; ElfW(Addr) caller = (ElfW(Addr)) who; /* If the address is not recognized the call comes from the main program (we hope). */ struct link_map *match = GL(dl_ns)[LM_ID_BASE]._ns_loaded; /* Find the highest-addressed object that CALLER is not below. */ for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns) for (struct link_map *l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next) if (caller >= l->l_map_start && caller < l->l_map_end && (l->l_contiguous || _dl_addr_inside_object (l, caller))) { match = l; break; } if (handle == RTLD_DEFAULT) { /* Search the global scope. We have the simple case where we look up in the scope of an object which was part of the initial binary. And then the more complex part where the object is dynamically loaded and the scope array can change. */ if (RTLD_SINGLE_THREAD_P) result = GLRO(dl_lookup_symbol_x) (name, match, &ref, match->l_scope, vers, 0, flags | DL_LOOKUP_ADD_DEPENDENCY, NULL); else { struct call_dl_lookup_args args; args.name = name; args.map = match; args.vers = vers; args.flags = flags | DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_GSCOPE_LOCK; args.refp = &ref; THREAD_GSCOPE_SET_FLAG (); const char *objname; const char *errstring = NULL; bool malloced; int err = GLRO(dl_catch_error) (&objname, &errstring, &malloced, call_dl_lookup, &args); THREAD_GSCOPE_RESET_FLAG (); if (__builtin_expect (errstring != NULL, 0)) { /* The lookup was unsuccessful. Rethrow the error. */ char *errstring_dup = strdupa (errstring); char *objname_dup = strdupa (objname); if (malloced) free ((char *) errstring); GLRO(dl_signal_error) (err, objname_dup, NULL, errstring_dup); /* NOTREACHED */ } result = args.map; } } else if (handle == RTLD_NEXT) { if (__builtin_expect (match == GL(dl_ns)[LM_ID_BASE]._ns_loaded, 0)) { if (match == NULL || caller < match->l_map_start || caller >= match->l_map_end) GLRO(dl_signal_error) (0, NULL, NULL, N_("\ RTLD_NEXT used in code not dynamically loaded")); } struct link_map *l = match; while (l->l_loader != NULL) l = l->l_loader; result = GLRO(dl_lookup_symbol_x) (name, match, &ref, l->l_local_scope, vers, 0, 0, match); } else { /* Search the scope of the given object. */ struct link_map *map = handle; result = GLRO(dl_lookup_symbol_x) (name, map, &ref, map->l_local_scope, vers, 0, flags, NULL); } if (ref != NULL) { void *value; #ifdef SHARED if (ELFW(ST_TYPE) (ref->st_info) == STT_TLS) /* The found symbol is a thread-local storage variable. Return the address for to the current thread. */ value = _dl_tls_symaddr (result, ref); else #endif value = DL_SYMBOL_ADDRESS (result, ref); #ifdef SHARED /* Auditing checkpoint: we have a new binding. Provide the auditing libraries the possibility to change the value and tell us whether further auditing is wanted. */ if (__builtin_expect (GLRO(dl_naudit) > 0, 0)) { const char *strtab = (const char *) D_PTR (result, l_info[DT_STRTAB]); /* Compute index of the symbol entry in the symbol table of the DSO with the definition. */ unsigned int ndx = (ref - (ElfW(Sym) *) D_PTR (result, l_info[DT_SYMTAB])); if ((match->l_audit_any_plt | result->l_audit_any_plt) != 0) { unsigned int altvalue = 0; struct audit_ifaces *afct = GLRO(dl_audit); /* Synthesize a symbol record where the st_value field is the result. */ ElfW(Sym) sym = *ref; sym.st_value = (ElfW(Addr)) value; for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt) { if (afct->symbind != NULL && ((match->l_audit[cnt].bindflags & LA_FLG_BINDFROM) != 0 || ((result->l_audit[cnt].bindflags & LA_FLG_BINDTO) != 0))) { unsigned int flags = altvalue | LA_SYMB_DLSYM; uintptr_t new_value = afct->symbind (&sym, ndx, &match->l_audit[cnt].cookie, &result->l_audit[cnt].cookie, &flags, strtab + ref->st_name); if (new_value != (uintptr_t) sym.st_value) { altvalue = LA_SYMB_ALTVALUE; sym.st_value = new_value; } } afct = afct->next; } value = (void *) sym.st_value; } } #endif return value; } return NULL; } void * internal_function _dl_vsym (void *handle, const char *name, const char *version, void *who) { struct r_found_version vers; /* Compute hash value to the version string. */ vers.name = version; vers.hidden = 1; vers.hash = _dl_elf_hash (version); /* We don't have a specific file where the symbol can be found. */ vers.filename = NULL; return do_sym (handle, name, who, &vers, 0); } void * internal_function _dl_sym (void *handle, const char *name, void *who) { return do_sym (handle, name, who, NULL, DL_LOOKUP_RETURN_NEWEST); }