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1325 |
phoenix |
/* vi: set sw=4 ts=4: */
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/* Program to load an ELF binary on a linux system, and run it
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* after resolving ELF shared library symbols
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*
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* Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
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* David Engel, Hongjiu Lu and Mitch D'Souza
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* Copyright (C) 2001-2002, Erik Andersen
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*
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. The name of the above contributors may not be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/* Various symbol table handling functions, including symbol lookup */
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/*
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* This is the start of the linked list that describes all of the files present
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* in the system with pointers to all of the symbol, string, and hash tables,
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* as well as all of the other good stuff in the binary.
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*/
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struct elf_resolve *_dl_loaded_modules = NULL;
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/*
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* This is the list of modules that are loaded when the image is first
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* started. As we add more via dlopen, they get added into other
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* chains.
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*/
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struct dyn_elf *_dl_symbol_tables = NULL;
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/*
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* This is the list of modules that are loaded via dlopen. We may need
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* to search these for RTLD_GLOBAL files.
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*/
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struct dyn_elf *_dl_handles = NULL;
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/*
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* This is the hash function that is used by the ELF linker to generate
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* the hash table that each executable and library is required to
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* have. We need it to decode the hash table.
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*/
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unsigned long _dl_elf_hash(const char *name)
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{
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unsigned long hash = 0;
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unsigned long tmp;
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while (*name) {
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hash = (hash << 4) + *name++;
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if ((tmp = hash & 0xf0000000))
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hash ^= tmp >> 24;
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hash &= ~tmp;
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};
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return hash;
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}
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/*
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* Check to see if a library has already been added to the hash chain.
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*/
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struct elf_resolve *_dl_check_hashed_files(const char *libname)
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{
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struct elf_resolve *tpnt;
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int len = _dl_strlen(libname);
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for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) {
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if (_dl_strncmp(tpnt->libname, libname, len) == 0 &&
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(tpnt->libname[len] == '\0' || tpnt->libname[len] == '.'))
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return tpnt;
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}
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return NULL;
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}
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/*
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* We call this function when we have just read an ELF library or executable.
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* We add the relevant info to the symbol chain, so that we can resolve all
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* externals properly.
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*/
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struct elf_resolve *_dl_add_elf_hash_table(const char *libname,
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char *loadaddr, unsigned long *dynamic_info, unsigned long dynamic_addr,
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unsigned long dynamic_size)
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{
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unsigned long *hash_addr;
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struct elf_resolve *tpnt;
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int i;
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if (!_dl_loaded_modules) {
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tpnt = _dl_loaded_modules =
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(struct elf_resolve *) _dl_malloc(sizeof(struct elf_resolve));
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_dl_memset(tpnt, 0, sizeof(struct elf_resolve));
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} else {
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tpnt = _dl_loaded_modules;
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while (tpnt->next)
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tpnt = tpnt->next;
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tpnt->next = (struct elf_resolve *) _dl_malloc(sizeof(struct elf_resolve));
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_dl_memset(tpnt->next, 0, sizeof(struct elf_resolve));
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tpnt->next->prev = tpnt;
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tpnt = tpnt->next;
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};
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tpnt->next = NULL;
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tpnt->init_flag = 0;
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tpnt->libname = _dl_strdup(libname);
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tpnt->dynamic_addr = (ElfW(Dyn) *)dynamic_addr;
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tpnt->dynamic_size = dynamic_size;
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tpnt->libtype = loaded_file;
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if (dynamic_info[DT_HASH] != 0) {
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hash_addr = (unsigned long *) (intptr_t)(dynamic_info[DT_HASH] + loadaddr);
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tpnt->nbucket = *hash_addr++;
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tpnt->nchain = *hash_addr++;
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tpnt->elf_buckets = hash_addr;
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hash_addr += tpnt->nbucket;
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tpnt->chains = hash_addr;
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}
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tpnt->loadaddr = (ElfW(Addr))loadaddr;
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for (i = 0; i < 24; i++)
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tpnt->dynamic_info[i] = dynamic_info[i];
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#ifdef __mips__
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{
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Elf32_Dyn *dpnt = (Elf32_Dyn *) dynamic_addr;
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while(dpnt->d_tag) {
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if (dpnt->d_tag == DT_MIPS_GOTSYM)
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tpnt->mips_gotsym = dpnt->d_un.d_val;
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if (dpnt->d_tag == DT_MIPS_LOCAL_GOTNO)
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tpnt->mips_local_gotno = dpnt->d_un.d_val;
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if (dpnt->d_tag == DT_MIPS_SYMTABNO)
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tpnt->mips_symtabno = dpnt->d_un.d_val;
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dpnt++;
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}
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}
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#endif
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return tpnt;
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}
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/*
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* This function resolves externals, and this is either called when we process
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* relocations or when we call an entry in the PLT table for the first time.
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*/
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char *_dl_find_hash(const char *name, struct dyn_elf *rpnt1,
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struct elf_resolve *f_tpnt, enum caller_type caller_type)
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{
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struct elf_resolve *tpnt;
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int si;
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char *pnt;
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int pass;
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char *strtab;
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Elf32_Sym *symtab;
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unsigned long elf_hash_number, hn;
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char *weak_result;
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struct elf_resolve *first_def;
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struct dyn_elf *rpnt, first;
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char *data_result = 0; /* nakao */
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weak_result = 0;
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elf_hash_number = _dl_elf_hash(name);
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/* A quick little hack to make sure that any symbol in the executable
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will be preferred to one in a shared library. This is necessary so
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that any shared library data symbols referenced in the executable
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will be seen at the same address by the executable, shared libraries
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and dynamically loaded code. -Rob Ryan (robr@cmu.edu) */
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if (_dl_symbol_tables && !caller_type && rpnt1) {
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first = (*_dl_symbol_tables);
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first.next = rpnt1;
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rpnt1 = (&first);
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}
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| 194 |
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/*
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* The passes are so that we can first search the regular symbols
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* for whatever module was specified, and then search anything
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* loaded with RTLD_GLOBAL. When pass is 1, it means we are just
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* starting the first dlopened module, and anything above that
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* is just the next one in the chain.
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*/
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for (pass = 0; (1 == 1); pass++) {
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/*
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* If we are just starting to search for RTLD_GLOBAL, setup
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* the pointer for the start of the search.
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*/
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if (pass == 1) {
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rpnt1 = _dl_handles;
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}
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/*
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* Anything after this, we need to skip to the next module.
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*/
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else if (pass >= 2) {
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rpnt1 = rpnt1->next_handle;
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}
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/*
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* Make sure we still have a module, and make sure that this
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* module was loaded with RTLD_GLOBAL.
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*/
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if (pass != 0) {
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if (rpnt1 == NULL)
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break;
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if ((rpnt1->flags & RTLD_GLOBAL) == 0)
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continue;
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}
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for (rpnt = (rpnt1 ? rpnt1 : _dl_symbol_tables); rpnt; rpnt = rpnt->next) {
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tpnt = rpnt->dyn;
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/*
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* The idea here is that if we are using dlsym, we want to
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* first search the entire chain loaded from dlopen, and
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* return a result from that if we found anything. If this
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* fails, then we continue the search into the stuff loaded
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* when the image was activated. For normal lookups, we start
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* with rpnt == NULL, so we should never hit this.
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*/
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| 240 |
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if (tpnt->libtype == elf_executable && weak_result != 0) {
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break;
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| 242 |
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}
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| 243 |
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| 244 |
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/*
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| 245 |
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* Avoid calling .urem here.
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| 246 |
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*/
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| 247 |
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do_rem(hn, elf_hash_number, tpnt->nbucket);
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| 248 |
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symtab = (Elf32_Sym *) (intptr_t) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
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| 249 |
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strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
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| 250 |
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/*
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| 251 |
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* This crap is required because the first instance of a
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| 252 |
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* symbol on the chain will be used for all symbol references.
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| 253 |
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* Thus this instance must be resolved to an address that
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| 254 |
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* contains the actual function,
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| 255 |
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*/
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| 256 |
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| 257 |
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first_def = NULL;
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| 258 |
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| 259 |
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for (si = tpnt->elf_buckets[hn]; si; si = tpnt->chains[si]) {
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| 260 |
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pnt = strtab + symtab[si].st_name;
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| 261 |
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| 262 |
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if (_dl_strcmp(pnt, name) == 0 &&
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| 263 |
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symtab[si].st_value != 0)
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| 264 |
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{
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| 265 |
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if ((ELF32_ST_TYPE(symtab[si].st_info) == STT_FUNC ||
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| 266 |
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ELF32_ST_TYPE(symtab[si].st_info) == STT_NOTYPE ||
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| 267 |
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ELF32_ST_TYPE(symtab[si].st_info) == STT_OBJECT) &&
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| 268 |
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symtab[si].st_shndx != SHN_UNDEF) {
|
| 269 |
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|
| 270 |
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/* Here we make sure that we find a module where the symbol is
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| 271 |
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* actually defined.
|
| 272 |
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*/
|
| 273 |
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|
| 274 |
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if (f_tpnt) {
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| 275 |
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if (!first_def)
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| 276 |
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first_def = tpnt;
|
| 277 |
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if (first_def == f_tpnt
|
| 278 |
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&& symtab[si].st_shndx == 0)
|
| 279 |
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continue;
|
| 280 |
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}
|
| 281 |
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|
|
| 282 |
|
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switch (ELF32_ST_BIND(symtab[si].st_info)) {
|
| 283 |
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case STB_GLOBAL:
|
| 284 |
|
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if (tpnt->libtype != elf_executable &&
|
| 285 |
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ELF32_ST_TYPE(symtab[si].st_info)
|
| 286 |
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== STT_NOTYPE)
|
| 287 |
|
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{ /* nakao */
|
| 288 |
|
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data_result = (char *)tpnt->loadaddr +
|
| 289 |
|
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symtab[si].st_value; /* nakao */
|
| 290 |
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break; /* nakao */
|
| 291 |
|
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} else /* nakao */
|
| 292 |
|
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return (char*)tpnt->loadaddr + symtab[si].st_value;
|
| 293 |
|
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case STB_WEAK:
|
| 294 |
|
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if (!weak_result)
|
| 295 |
|
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weak_result = (char *)tpnt->loadaddr + symtab[si].st_value;
|
| 296 |
|
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break;
|
| 297 |
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default: /* Do local symbols need to be examined? */
|
| 298 |
|
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break;
|
| 299 |
|
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}
|
| 300 |
|
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}
|
| 301 |
|
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#ifndef __mips__
|
| 302 |
|
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/*
|
| 303 |
|
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* References to the address of a function from an executable file and
|
| 304 |
|
|
* the shared objects associated with it might not resolve to the same
|
| 305 |
|
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* value. To allow comparisons of function addresses we must resolve
|
| 306 |
|
|
* to the address of the plt entry of the executable instead of the
|
| 307 |
|
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* real function address.
|
| 308 |
|
|
* see "TIS ELF Specification Version 1.2, Book 3, A-11 (Function
|
| 309 |
|
|
* Adresses)
|
| 310 |
|
|
*/
|
| 311 |
|
|
if (resolver != caller_type &&
|
| 312 |
|
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NULL==f_tpnt && /*trick: don't handle R_??_JMP_SLOT reloc type*/
|
| 313 |
|
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tpnt->libtype == elf_executable &&
|
| 314 |
|
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ELF32_ST_TYPE(symtab[si].st_info) == STT_FUNC &&
|
| 315 |
|
|
symtab[si].st_shndx == SHN_UNDEF)
|
| 316 |
|
|
{
|
| 317 |
|
|
return (char*)symtab[si].st_value;
|
| 318 |
|
|
}
|
| 319 |
|
|
#endif
|
| 320 |
|
|
}
|
| 321 |
|
|
}
|
| 322 |
|
|
}
|
| 323 |
|
|
}
|
| 324 |
|
|
if (data_result)
|
| 325 |
|
|
return data_result; /* nakao */
|
| 326 |
|
|
return weak_result;
|
| 327 |
|
|
}
|
