/* vi: set sw=4 ts=4: */ /* Program to load an ELF binary on a linux system, and run it * after resolving ELF shared library symbols * * Copyright (C) 1993-1996, Eric Youngdale. * Copyright (C) 2001-2002, Erik Andersen * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * * This program 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 General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* Enable this to turn on debugging noise */ //#define DL_DEBUG /* Enable mprotect protection munging. ARM Linux needs this it seems, * so leave this enabled by default */ #define DO_MPROTECT_HACKS // Support a list of library preloads in /etc/ld.so.preload //#define SUPPORT_LDSO_PRELOAD_FILE /* Enable ldd library tracing. Just set LD_TRACE_LOADED_OBJECTS=1 in * the environment and run the app to do the ldd thing. With this * enabled you can make a simple /usr/bin/ldd shell script as: * #!/bin/sh * LD_TRACE_LOADED_OBJECTS=1 $1 * so you can do stuff like: * $ ldd ./appname * libc.so.0 => /lib/libc.so.0 (0x0x40006000) * ld-uClibc.so.0 => /home/andersen/CVS/uClibc/lib/ld-uClibc.so.0 (0x0x40000000) * This is off by default since it doesn't work when cross compiling, * so uClibc provides an ELF header reading ldd instead... */ //#define DL_TRACE /* Disclaimer: I have never seen any AT&T source code for SVr4, nor have I ever taken any courses on internals. This program was developed using information available through the book "UNIX SYSTEM V RELEASE 4, Programmers guide: Ansi C and Programming Support Tools", which did a more than adequate job of explaining everything required to get this working. */ /* * The main trick with this program is that initially, we ourselves are * not dynamicly linked. This means that we cannot access any global * variables or call any functions. No globals initially, since the * Global Offset Table (GOT) is initialized by the linker assuming a * virtual address of 0, and no function calls initially since the * Procedure Linkage Table (PLT) is not yet initialized. * * There are additional initial restrictions - we cannot use large * switch statements, since the compiler generates tables of addresses * and jumps through them. We can use inline functions, because these * do not transfer control to a new address, but they must be static so * that they are not exported from the modules. We cannot use normal * syscall stubs, because these all reference the errno global variable * which is not yet initialized. We can use all of the local stack * variables that we want. * * Life is further complicated by the fact that initially we do not * want to do a complete dynamic linking. We want to allow the user to * supply new functions to override symbols (i.e. weak symbols and/or * LD_PRELOAD). So initially, we only perform relocations for * variables that start with "_dl_" since ANSI specifies that the user * is not supposed to redefine any of these variables. * * Fortunately, the linker itself leaves a few clues lying around, and * when the kernel starts the image, there are a few further clues. * First of all, there is Auxiliary Vector Table information sitting on * which is provided to us by the kernel, and which includes * information about the load address that the program interpreter was * loaded at, the number of sections, the address the application was * loaded at and so forth. Here this information is stored in the * array auxvt. For details see linux/fs/binfmt_elf.c where it calls * NEW_AUX_ENT() a bunch of time.... * * Next, we need to find the GOT. On most arches there is a register * pointing to the GOT, but just in case (and for new ports) I've added * some (slow) C code to locate the GOT for you. * * This code was originally written for SVr4, and there the kernel * would load all text pages R/O, so they needed to call mprotect a * zillion times to mark all text pages as writable so dynamic linking * would succeed. Then when they were done, they would change the * protections for all the pages back again. Well, under Linux * everything is loaded writable (since Linux does copy on write * anyways) so all the mprotect stuff has been disabled. * * Initially, we do not have access to _dl_malloc since we can't yet * make function calls, so we mmap one page to use as scratch space. * Later on, when we can call _dl_malloc we reuse this this memory. * This is also beneficial, since we do not want to use the same memory * pool as malloc anyway - esp if the user redefines malloc to do * something funky. * * Our first task is to perform a minimal linking so that we can call * other portions of the dynamic linker. Once we have done this, we * then build the list of modules that the application requires, using * LD_LIBRARY_PATH if this is not a suid program (/usr/lib otherwise). * Once this is done, we can do the dynamic linking as required, and we * must omit the things we did to get the dynamic linker up and running * in the first place. After we have done this, we just have a few * housekeeping chores and we can transfer control to the user's * application. */ #include "ld_syscall.h" #include "linuxelf.h" #include "ld_hash.h" #include "ld_string.h" #include "dlfcn.h" #include "../config.h" #define ALLOW_ZERO_PLTGOT /* Some arches may need to override this in boot1_arch.h */ #define ELFMAGIC ELFMAG /* This is a poor man's malloc, used prior to resolving our internal poor man's malloc */ #define DL_MALLOC(SIZE) ((void *) (malloc_buffer += SIZE, malloc_buffer - SIZE)) ; REALIGN(); /* * Make sure that the malloc buffer is aligned on 4 byte boundary. For 64 bit * platforms we may need to increase this to 8, but this is good enough for * now. This is typically called after DL_MALLOC. */ #define REALIGN() malloc_buffer = (char *) (((unsigned long) malloc_buffer + 3) & ~(3)) char *_dl_library_path = 0; /* Where we look for libraries */ char *_dl_preload = 0; /* Things to be loaded before the libs. */ char *_dl_ldsopath = 0; static char *_dl_not_lazy = 0; static char *_dl_malloc_addr, *_dl_mmap_zero; static char *_dl_trace_loaded_objects = 0; static int (*_dl_elf_main) (int, char **, char **); static int (*_dl_elf_init) (void); void *(*_dl_malloc_function) (int size) = NULL; struct r_debug *_dl_debug_addr = NULL; unsigned long *_dl_brkp; unsigned long *_dl_envp; char *_dl_getenv(char *symbol, char **envp); void _dl_unsetenv(char *symbol, char **envp); int _dl_fixup(struct elf_resolve *tpnt); void _dl_debug_state(void); char *_dl_get_last_path_component(char *path); static void _dl_get_ready_to_run(struct elf_resolve *tpnt, struct elf_resolve *app_tpnt, unsigned long load_addr, unsigned long *hash_addr, Elf32_auxv_t auxvt[AT_EGID + 1], char **envp, struct r_debug *debug_addr); #include "boot1_arch.h" #include "ldso.h" /* Pull in the name of ld.so */ /* When we enter this piece of code, the program stack looks like this: argc argument counter (integer) argv[0] program name (pointer) argv[1...N] program args (pointers) argv[argc-1] end of args (integer) NULL env[0...N] environment variables (pointers) NULL auxvt[0...N] Auxiliary Vector Table elements (mixed types) */ #ifdef DL_DEBUG /* Debugging is especially tricky on PowerPC, since string literals * require relocations. Thus, you can't use _dl_dprintf() for * anything until the bootstrap relocations are finished. */ static inline void hexprint(unsigned long x) { int i; char c; for (i = 0; i < 8; i++) { c = ((x >> 28) + '0'); if (c > '9') c += 'a' - '9' - 1; _dl_write(1, &c, 1); x <<= 4; } c = '\n'; _dl_write(1, &c, 1); } #endif DL_BOOT(unsigned long args) { unsigned int argc; char **argv, **envp; unsigned long load_addr; unsigned long *got; unsigned long *aux_dat; int goof = 0; elfhdr *header; struct elf_resolve *tpnt; struct elf_resolve *app_tpnt; Elf32_auxv_t auxvt[AT_EGID + 1]; unsigned char *malloc_buffer, *mmap_zero; Elf32_Dyn *dpnt; unsigned long *hash_addr; struct r_debug *debug_addr; int indx; int status; /* WARNING! -- we cannot make _any_ funtion calls until we have * taken care of fixing up our own relocations. Making static * inline calls is ok, but _no_ function calls. Not yet * anyways. */ /* First obtain the information on the stack that tells us more about what binary is loaded, where it is loaded, etc, etc */ GET_ARGV(aux_dat, args); #if defined(__arm__) aux_dat += 1; #endif argc = *(aux_dat - 1); argv = (char **) aux_dat; aux_dat += argc; /* Skip over the argv pointers */ aux_dat++; /* Skip over NULL at end of argv */ envp = (char **) aux_dat; while (*aux_dat) aux_dat++; /* Skip over the envp pointers */ aux_dat++; /* Skip over NULL at end of envp */ /* Place -1 here as a checkpoint. We later check if it was changed * when we read in the auxvt */ auxvt[AT_UID].a_type = -1; /* The junk on the stack immediately following the environment is * the Auxiliary Vector Table. Read out the elements of the auxvt, * sort and store them in auxvt for later use. */ while (*aux_dat) { Elf32_auxv_t *auxv_entry = (Elf32_auxv_t *) aux_dat; if (auxv_entry->a_type <= AT_EGID) { _dl_memcpy(&(auxvt[auxv_entry->a_type]), auxv_entry, sizeof(Elf32_auxv_t)); } aux_dat += 2; } /* locate the ELF header. We need this done as soon as possible * (esp since SEND_STDERR() needs this on some platforms... */ load_addr = auxvt[AT_BASE].a_un.a_val; header = (elfhdr *) auxvt[AT_BASE].a_un.a_ptr; /* Check the ELF header to make sure everything looks ok. */ if (!header || header->e_ident[EI_CLASS] != ELFCLASS32 || header->e_ident[EI_VERSION] != EV_CURRENT #ifndef __powerpc__ || _dl_strncmp((void *) header, ELFMAGIC, SELFMAG) != 0 #endif ) { SEND_STDERR("Invalid ELF header\n"); _dl_exit(0); } #ifdef DL_DEBUG SEND_STDERR("ELF header ="); SEND_ADDRESS_STDERR(load_addr, 1); #endif /* Locate the global offset table. Since this code must be PIC * we can take advantage of the magic offset register, if we * happen to know what that is for this architecture. If not, * we can always read stuff out of the ELF file to find it... */ #if defined(__i386__) __asm__("\tmovl %%ebx,%0\n\t":"=a"(got)); #elif defined(__m68k__) __asm__("movel %%a5,%0":"=g"(got)) #elif defined(__sparc__) __asm__("\tmov %%l7,%0\n\t":"=r"(got)) #elif defined(__arm__) __asm__("\tmov %0, r10\n\t":"=r"(got)); #elif defined(__powerpc__) __asm__("\tbl _GLOBAL_OFFSET_TABLE_-4@local\n\t":"=l"(got)); #else /* Do things the slow way in C */ { unsigned long tx_reloc; Elf32_Dyn *dynamic = NULL; Elf32_Shdr *shdr; Elf32_Phdr *pt_load; #ifdef DL_DEBUG SEND_STDERR("Finding the GOT using C code to read the ELF file\n"); #endif /* Find where the dynamic linking information section is hiding */ shdr = (Elf32_Shdr *) (header->e_shoff + (char *) header); for (indx = header->e_shnum; --indx >= 0; ++shdr) { if (shdr->sh_type == SHT_DYNAMIC) { goto found_dynamic; } } SEND_STDERR("missing dynamic linking information section \n"); _dl_exit(0); found_dynamic: dynamic = (Elf32_Dyn *) (shdr->sh_offset + (char *) header); /* Find where PT_LOAD is hiding */ pt_load = (Elf32_Phdr *) (header->e_phoff + (char *) header); for (indx = header->e_phnum; --indx >= 0; ++pt_load) { if (pt_load->p_type == PT_LOAD) { goto found_pt_load; } } SEND_STDERR("missing loadable program segment\n"); _dl_exit(0); found_pt_load: /* Now (finally) find where DT_PLTGOT is hiding */ tx_reloc = pt_load->p_vaddr - pt_load->p_offset; for (; DT_NULL != dynamic->d_tag; ++dynamic) { if (dynamic->d_tag == DT_PLTGOT) { goto found_got; } } SEND_STDERR("missing global offset table\n"); _dl_exit(0); found_got: got = (unsigned long *) (dynamic->d_un.d_val - tx_reloc + (char *) header); } #endif /* Now, finally, fix up the location of the dynamic stuff */ dpnt = (Elf32_Dyn *) (*got + load_addr); #ifdef DL_DEBUG SEND_STDERR("First Dynamic section entry="); SEND_ADDRESS_STDERR(dpnt, 1); #endif /* Call mmap to get a page of writable memory that can be used * for _dl_malloc throughout the shared lib loader. */ mmap_zero = malloc_buffer = _dl_mmap((void *) 0, 4096, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); if (_dl_mmap_check_error(mmap_zero)) { SEND_STDERR("dl_boot: mmap of a spare page failed!\n"); _dl_exit(13); } tpnt = DL_MALLOC(sizeof(struct elf_resolve)); _dl_memset(tpnt, 0, sizeof(*tpnt)); app_tpnt = DL_MALLOC(sizeof(struct elf_resolve)); _dl_memset(app_tpnt, 0, sizeof(*app_tpnt)); /* * This is used by gdb to locate the chain of shared libraries that are currently loaded. */ debug_addr = DL_MALLOC(sizeof(struct r_debug)); _dl_memset(debug_addr, 0, sizeof(*debug_addr)); /* OK, that was easy. Next scan the DYNAMIC section of the image. We are only doing ourself right now - we will have to do the rest later */ while (dpnt->d_tag) { if (dpnt->d_tag < 24) { tpnt->dynamic_info[dpnt->d_tag] = dpnt->d_un.d_val; if (dpnt->d_tag == DT_TEXTREL || SVR4_BUGCOMPAT) { tpnt->dynamic_info[DT_TEXTREL] = 1; } } dpnt++; } { elf_phdr *ppnt; int i; ppnt = (elf_phdr *) auxvt[AT_PHDR].a_un.a_ptr; for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) if (ppnt->p_type == PT_DYNAMIC) { dpnt = (Elf32_Dyn *) ppnt->p_vaddr; while (dpnt->d_tag) { if (dpnt->d_tag > DT_JMPREL) { dpnt++; continue; } app_tpnt->dynamic_info[dpnt->d_tag] = dpnt->d_un.d_val; if (dpnt->d_tag == DT_DEBUG) dpnt->d_un.d_val = (unsigned long) debug_addr; if (dpnt->d_tag == DT_TEXTREL || SVR4_BUGCOMPAT) app_tpnt->dynamic_info[DT_TEXTREL] = 1; dpnt++; } } } /* Get some more of the information that we will need to dynamicly link this module to itself */ hash_addr = (unsigned long *) (tpnt->dynamic_info[DT_HASH] + load_addr); tpnt->nbucket = *hash_addr++; tpnt->nchain = *hash_addr++; tpnt->elf_buckets = hash_addr; hash_addr += tpnt->nbucket; #ifdef DO_MPROTECT_HACKS /* Ugly, ugly. We need to call mprotect to change the protection of the text pages so that we can do the dynamic linking. We can set the protection back again once we are done */ { elf_phdr *ppnt; int i; /* First cover the shared library/dynamic linker. */ if (tpnt->dynamic_info[DT_TEXTREL]) { header = (elfhdr *) auxvt[AT_BASE].a_un.a_ptr; ppnt = (elf_phdr *) (auxvt[AT_BASE].a_un.a_ptr + header->e_phoff); for (i = 0; i < header->e_phnum; i++, ppnt++) { if (ppnt->p_type == PT_LOAD && !(ppnt->p_flags & PF_W)) { _dl_mprotect((void *) (load_addr + (ppnt->p_vaddr & 0xfffff000)), (ppnt->p_vaddr & 0xfff) + (unsigned long) ppnt->p_filesz, PROT_READ | PROT_WRITE | PROT_EXEC); } } } /* Now cover the application program. */ if (app_tpnt->dynamic_info[DT_TEXTREL]) { ppnt = (elf_phdr *) auxvt[AT_PHDR].a_un.a_ptr; for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) { if (ppnt->p_type == PT_LOAD && !(ppnt->p_flags & PF_W)) _dl_mprotect((void *) (ppnt->p_vaddr & 0xfffff000), (ppnt->p_vaddr & 0xfff) + (unsigned long) ppnt->p_filesz, PROT_READ | PROT_WRITE | PROT_EXEC); } } } #endif /* OK, now do the relocations. We do not do a lazy binding here, so that once we are done, we have considerably more flexibility. */ #ifdef DL_DEBUG SEND_STDERR("About to do library loader relocations.\n"); #endif goof = 0; for (indx = 0; indx < 2; indx++) { int i; ELF_RELOC *rpnt; unsigned long *reloc_addr; unsigned long symbol_addr; int symtab_index; unsigned long rel_addr, rel_size; #ifdef ELF_USES_RELOCA rel_addr = (indx ? tpnt->dynamic_info[DT_JMPREL] : tpnt-> dynamic_info[DT_RELA]); rel_size = (indx ? tpnt->dynamic_info[DT_PLTRELSZ] : tpnt-> dynamic_info[DT_RELASZ]); #else rel_addr = (indx ? tpnt->dynamic_info[DT_JMPREL] : tpnt-> dynamic_info[DT_REL]); rel_size = (indx ? tpnt->dynamic_info[DT_PLTRELSZ] : tpnt-> dynamic_info[DT_RELSZ]); #endif if (!rel_addr) continue; /* Now parse the relocation information */ rpnt = (ELF_RELOC *) (rel_addr + load_addr); for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) { reloc_addr = (unsigned long *) (load_addr + (unsigned long) rpnt->r_offset); symtab_index = ELF32_R_SYM(rpnt->r_info); symbol_addr = 0; if (symtab_index) { char *strtab; Elf32_Sym *symtab; symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + load_addr); strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + load_addr); /* We only do a partial dynamic linking right now. The user is not supposed to redefine any symbols that start with a '_', so we can do this with confidence. */ if (!_dl_symbol(strtab + symtab[symtab_index].st_name)) continue; symbol_addr = load_addr + symtab[symtab_index].st_value; if (!symbol_addr) { /* This will segfault - you cannot call a function until * we have finished the relocations. */ SEND_STDERR("ELF dynamic loader - unable to self-bootstrap - symbol "); SEND_STDERR(strtab + symtab[symtab_index].st_name); SEND_STDERR(" undefined.\n"); goof++; } #ifdef DL_DEBUG_SYMBOLS SEND_STDERR("About to fixup symbol: "); SEND_STDERR(strtab + symtab[symtab_index].st_name); SEND_STDERR("\n"); #endif } /* * Use this machine-specific macro to perform the actual relocation. */ PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr); } } if (goof) { _dl_exit(14); } #ifdef DL_DEBUG /* Wahoo!!! */ _dl_dprintf(2, "Done relocating library loader, so we can now\n\tuse globals and make function calls!\n"); #endif if (argv[0]) { _dl_progname = argv[0]; } /* Start to build the tables of the modules that are required for * this beast to run. We start with the basic executable, and then * go from there. Eventually we will run across ourself, and we * will need to properly deal with that as well. */ /* Make it so _dl_malloc can use the page of memory we have already * allocated, so we shouldn't need to grab any more memory */ _dl_malloc_addr = malloc_buffer; _dl_mmap_zero = mmap_zero; /* Now we have done the mandatory linking of some things. We are now free to start using global variables, since these things have all been fixed up by now. Still no function calls outside of this library , since the dynamic resolver is not yet ready. */ _dl_get_ready_to_run(tpnt, app_tpnt, load_addr, hash_addr, auxvt, envp, debug_addr); /* OK we are done here. Turn out the lights, and lock up. */ _dl_elf_main = (int (*)(int, char **, char **)) auxvt[AT_ENTRY].a_un.a_fcn; /* * Transfer control to the application. */ status = 0; /* Used on x86, but not on other arches */ #ifdef DL_DEBUG _dl_dprintf(2, "Calling application main()\n"); #endif START(); } static void _dl_get_ready_to_run(struct elf_resolve *tpnt, struct elf_resolve *app_tpnt, unsigned long load_addr, unsigned long *hash_addr, Elf32_auxv_t auxvt[AT_EGID + 1], char **envp, struct r_debug *debug_addr) { elf_phdr *ppnt; char *lpntstr; int i, _dl_secure, goof = 0; struct dyn_elf *rpnt; struct elf_resolve *tcurr; struct elf_resolve *tpnt1; unsigned long brk_addr, *lpnt; int (*_dl_atexit) (void *); /* Now we have done the mandatory linking of some things. We are now free to start using global variables, since these things have all been fixed up by now. Still no function calls outside of this library , since the dynamic resolver is not yet ready. */ lpnt = (unsigned long *) (tpnt->dynamic_info[DT_PLTGOT] + load_addr); INIT_GOT(lpnt, tpnt); #ifdef DL_DEBUG _dl_dprintf(2, "GOT found at %x\n", tpnt); #endif /* OK, this was a big step, now we need to scan all of the user images and load them properly. */ tpnt->next = 0; tpnt->libname = 0; tpnt->libtype = program_interpreter; { elfhdr *epnt; elf_phdr *ppnt; int i; epnt = (elfhdr *) auxvt[AT_BASE].a_un.a_ptr; tpnt->n_phent = epnt->e_phnum; tpnt->ppnt = ppnt = (elf_phdr *) (load_addr + epnt->e_phoff); for (i = 0; i < epnt->e_phnum; i++, ppnt++) { if (ppnt->p_type == PT_DYNAMIC) { tpnt->dynamic_addr = ppnt->p_vaddr + load_addr; tpnt->dynamic_size = ppnt->p_filesz; } } } tpnt->chains = hash_addr; tpnt->loadaddr = (char *) load_addr; brk_addr = 0; rpnt = NULL; /* At this point we are now free to examine the user application, and figure out which libraries are supposed to be called. Until we have this list, we will not be completely ready for dynamic linking */ ppnt = (elf_phdr *) auxvt[AT_PHDR].a_un.a_ptr; for (i = 0; i < auxvt[AT_PHNUM].a_un.a_val; i++, ppnt++) { if (ppnt->p_type == PT_LOAD) { if (ppnt->p_vaddr + ppnt->p_memsz > brk_addr) brk_addr = ppnt->p_vaddr + ppnt->p_memsz; } if (ppnt->p_type == PT_DYNAMIC) { #ifndef ALLOW_ZERO_PLTGOT /* make sure it's really there. */ if (app_tpnt->dynamic_info[DT_PLTGOT] == 0) continue; #endif /* OK, we have what we need - slip this one into the list. */ app_tpnt = _dl_add_elf_hash_table("", 0, app_tpnt->dynamic_info, ppnt->p_vaddr, ppnt->p_filesz); _dl_loaded_modules->libtype = elf_executable; _dl_loaded_modules->ppnt = (elf_phdr *) auxvt[AT_PHDR].a_un.a_ptr; _dl_loaded_modules->n_phent = auxvt[AT_PHNUM].a_un.a_val; _dl_symbol_tables = rpnt = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt, 0, sizeof(*rpnt)); rpnt->dyn = _dl_loaded_modules; app_tpnt->usage_count++; app_tpnt->symbol_scope = _dl_symbol_tables; lpnt = (unsigned long *) (app_tpnt->dynamic_info[DT_PLTGOT]); #ifdef ALLOW_ZERO_PLTGOT if (lpnt) #endif INIT_GOT(lpnt, _dl_loaded_modules); } /* OK, fill this in - we did not have this before */ if (ppnt->p_type == PT_INTERP) { int readsize = 0; char *pnt, *pnt1, buf[1024]; tpnt->libname = _dl_strdup((char *) ppnt->p_offset + (auxvt[AT_PHDR].a_un.a_val & 0xfffff000)); /* Determine if the shared lib loader is a symlink */ _dl_memset(buf, 0, sizeof(buf)); readsize = _dl_readlink(tpnt->libname, buf, sizeof(buf)); if (readsize > 0 && readsize < sizeof(buf)-1) { pnt1 = _dl_strrchr(buf, '/'); if (pnt1 && buf != pnt1) { #ifdef DL_DEBUG _dl_dprintf(2, "changing tpnt->libname from '%s' to '%s'\n", tpnt->libname, buf); #endif tpnt->libname = _dl_strdup(buf); } } /* Store the path where the shared lib loader was found for * later use */ pnt = _dl_strdup(tpnt->libname); pnt1 = _dl_strrchr(pnt, '/'); if (pnt != pnt1) { *pnt1 = '\0'; _dl_ldsopath = pnt; } else { _dl_ldsopath = tpnt->libname; } #ifdef DL_DEBUG _dl_dprintf(2, "Lib Loader:\t(%x) %s\n", tpnt->loadaddr, tpnt->libname); #endif } } /* Now we need to figure out what kind of options are selected. Note that for SUID programs we ignore the settings in LD_LIBRARY_PATH */ { _dl_not_lazy = _dl_getenv("LD_BIND_NOW", envp); if ((auxvt[AT_UID].a_un.a_val == -1 && _dl_suid_ok()) || (auxvt[AT_UID].a_un.a_val != -1 && auxvt[AT_UID].a_un.a_val == auxvt[AT_EUID].a_un.a_val && auxvt[AT_GID].a_un.a_val== auxvt[AT_EGID].a_un.a_val)) { _dl_secure = 0; _dl_preload = _dl_getenv("LD_PRELOAD", envp); _dl_library_path = _dl_getenv("LD_LIBRARY_PATH", envp); } else { _dl_secure = 1; _dl_preload = _dl_getenv("LD_PRELOAD", envp); _dl_unsetenv("LD_AOUT_PRELOAD", envp); _dl_unsetenv("LD_LIBRARY_PATH", envp); _dl_unsetenv("LD_AOUT_LIBRARY_PATH", envp); _dl_library_path = NULL; } } _dl_trace_loaded_objects = _dl_getenv("LD_TRACE_LOADED_OBJECTS", envp); #ifndef DL_TRACE if (_dl_trace_loaded_objects) { _dl_dprintf(2, "Use the ldd provided by uClibc\n"); _dl_exit(1); } #endif /* OK, we now have the application in the list, and we have some basic stuff in place. Now search through the list for other shared libraries that should be loaded, and insert them on the list in the correct order. */ #ifdef USE_CACHE _dl_map_cache(); #endif if (_dl_preload) { char c, *str, *str2; str = _dl_preload; while (*str == ':' || *str == ' ' || *str == '\t') str++; while (*str) { str2 = str; while (*str2 && *str2 != ':' && *str2 != ' ' && *str2 != '\t') str2++; c = *str2; *str2 = '\0'; if (!_dl_secure || _dl_strchr(str, '/') == NULL) { tpnt1 = _dl_load_shared_library(_dl_secure, NULL, str); if (!tpnt1) { #ifdef DL_TRACE if (_dl_trace_loaded_objects) _dl_dprintf(1, "\t%s => not found\n", str); else { #endif _dl_dprintf(2, "%s: can't load " "library '%s'\n", _dl_progname, str); _dl_exit(15); #ifdef DL_TRACE } #endif } else { #ifdef DL_DEBUG _dl_dprintf(2, "Loading:\t(%x) %s\n", tpnt1->loadaddr, tpnt1->libname); #endif #ifdef DL_TRACE if (_dl_trace_loaded_objects && !tpnt1->usage_count) { /* this is a real hack to make ldd not print * the library itself when run on a library. */ if (_dl_strcmp(_dl_progname, str) != 0) _dl_dprintf(1, "\t%s => %s (0x%x)\n", str, tpnt1->libname, (unsigned) tpnt1->loadaddr); } #endif rpnt->next = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt->next, 0, sizeof(*(rpnt->next))); rpnt = rpnt->next; tpnt1->usage_count++; tpnt1->symbol_scope = _dl_symbol_tables; tpnt1->libtype = elf_lib; rpnt->dyn = tpnt1; } } *str2 = c; str = str2; while (*str == ':' || *str == ' ' || *str == '\t') str++; } } #ifdef SUPPORT_LDSO_PRELOAD_FILE { int fd; struct stat st; char *preload; if (!_dl_stat(LDSO_PRELOAD, &st) && st.st_size > 0) { if ((fd = _dl_open(LDSO_PRELOAD, O_RDONLY)) < 0) { _dl_dprintf(2, "%s: can't open file '%s'\n", _dl_progname, LDSO_PRELOAD); } else { preload = (caddr_t) _dl_mmap(0, st.st_size + 1, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); _dl_close(fd); if (preload == (caddr_t) - 1) { _dl_dprintf(2, "%s: can't map file '%s'\n", _dl_progname, LDSO_PRELOAD); } else { char c, *cp, *cp2; /* convert all separators and comments to spaces */ for (cp = preload; *cp; /*nada */ ) { if (*cp == ':' || *cp == '\t' || *cp == '\n') { *cp++ = ' '; } else if (*cp == '#') { do *cp++ = ' '; while (*cp != '\n' && *cp != '\0'); } else { cp++; } } /* find start of first library */ for (cp = preload; *cp && *cp == ' '; cp++) /*nada */ ; while (*cp) { /* find end of library */ for (cp2 = cp; *cp && *cp != ' '; cp++) /*nada */ ; c = *cp; *cp = '\0'; tpnt1 = _dl_load_shared_library(0, NULL, cp2); if (!tpnt1) { #ifdef DL_TRACE if (_dl_trace_loaded_objects) _dl_dprintf(1, "\t%s => not found\n", cp2); else { #endif _dl_dprintf(2, "%s: can't load library '%s'\n", _dl_progname, cp2); _dl_exit(15); #ifdef DL_TRACE } #endif } else { #ifdef DL_DEBUG _dl_dprintf(2, "Loading:\t(%x) %s\n", tpnt1->loadaddr, tpnt1->libname); #endif #ifdef DL_TRACE if (_dl_trace_loaded_objects && !tpnt1->usage_count) { _dl_dprintf(1, "\t%s => %s (0x%x)\n", cp2, tpnt1->libname, (unsigned) tpnt1->loadaddr); } #endif rpnt->next = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt->next, 0, sizeof(*(rpnt->next))); rpnt = rpnt->next; tpnt1->usage_count++; tpnt1->symbol_scope = _dl_symbol_tables; tpnt1->libtype = elf_lib; rpnt->dyn = tpnt1; } /* find start of next library */ *cp = c; for ( /*nada */ ; *cp && *cp == ' '; cp++) /*nada */ ; } _dl_munmap(preload, st.st_size + 1); } } } } #endif for (tcurr = _dl_loaded_modules; tcurr; tcurr = tcurr->next) { Elf32_Dyn *dpnt; for (dpnt = (Elf32_Dyn *) tcurr->dynamic_addr; dpnt->d_tag; dpnt++) { if (dpnt->d_tag == DT_NEEDED) { lpntstr = tcurr->loadaddr + tcurr->dynamic_info[DT_STRTAB] + dpnt->d_un.d_val; if (_dl_strcmp(lpntstr, "libc.so.6") == 0) { _dl_dprintf(2, "%s: linked against GNU libc!\n", _dl_progname); _dl_exit(150); } if (tpnt && _dl_strcmp(lpntstr, _dl_get_last_path_component(tpnt->libname)) == 0) { struct elf_resolve *ttmp; #ifdef DL_TRACE if (_dl_trace_loaded_objects && !tpnt->usage_count) { _dl_dprintf(1, "\t%s => %s (0x%x)\n", lpntstr, tpnt->libname, (unsigned) tpnt->loadaddr); } #endif ttmp = _dl_loaded_modules; while (ttmp->next) ttmp = ttmp->next; ttmp->next = tpnt; tpnt->prev = ttmp; tpnt->next = NULL; rpnt->next = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt->next, 0, sizeof(*(rpnt->next))); rpnt = rpnt->next; rpnt->dyn = tpnt; tpnt->usage_count++; tpnt->symbol_scope = _dl_symbol_tables; tpnt = NULL; continue; } if (!(tpnt1 = _dl_load_shared_library(0, tcurr, lpntstr))) { #ifdef DL_TRACE if (_dl_trace_loaded_objects) _dl_dprintf(1, "\t%s => not found\n", lpntstr); else { #endif _dl_dprintf(2, "%s: can't load library '%s'\n", _dl_progname, lpntstr); _dl_exit(16); #ifdef DL_TRACE } #endif } else { #ifdef DL_DEBUG _dl_dprintf(2, "Loading:\t(%x) %s\n", tpnt1->loadaddr, tpnt1->libname); #endif #ifdef DL_TRACE if (_dl_trace_loaded_objects && !tpnt1->usage_count) _dl_dprintf(1, "\t%s => %s (0x%x)\n", lpntstr, tpnt1->libname, (unsigned) tpnt1->loadaddr); #endif rpnt->next = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt->next, 0, sizeof(*(rpnt->next))); rpnt = rpnt->next; tpnt1->usage_count++; tpnt1->symbol_scope = _dl_symbol_tables; tpnt1->libtype = elf_lib; rpnt->dyn = tpnt1; } } } } #ifdef USE_CACHE _dl_unmap_cache(); #endif /* ldd uses uses this. I am not sure how you pick up the other flags */ #ifdef DL_TRACE if (_dl_trace_loaded_objects) { char *_dl_warn = 0; _dl_warn = _dl_getenv("LD_WARN", envp); if (!_dl_warn) _dl_exit(0); } #endif /* * If the program interpreter is not in the module chain, add it. This will * be required for dlopen to be able to access the internal functions in the * dynamic linker. */ if (tpnt) { struct elf_resolve *tcurr; tcurr = _dl_loaded_modules; if (tcurr) while (tcurr->next) tcurr = tcurr->next; tpnt->next = NULL; tpnt->usage_count++; if (tcurr) { tcurr->next = tpnt; tpnt->prev = tcurr; } else { _dl_loaded_modules = tpnt; tpnt->prev = NULL; } if (rpnt) { rpnt->next = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt->next, 0, sizeof(*(rpnt->next))); rpnt = rpnt->next; } else { rpnt = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf)); _dl_memset(rpnt, 0, sizeof(*(rpnt->next))); } rpnt->dyn = tpnt; tpnt = NULL; } #ifdef DL_TRACE if (_dl_trace_loaded_objects) { _dl_dprintf(1, "\t%s => %s (0x%x)\n", rpnt->dyn->libname + (_dl_strlen(_dl_ldsopath)) + 1, rpnt->dyn->libname, rpnt->dyn->loadaddr); _dl_exit(0); } #endif #ifdef DL_DEBUG _dl_dprintf(2, "Beginning relocation fixups\n"); #endif /* * OK, now all of the kids are tucked into bed in their proper addresses. * Now we go through and look for REL and RELA records that indicate fixups * to the GOT tables. We need to do this in reverse order so that COPY * directives work correctly */ goof = _dl_loaded_modules ? _dl_fixup(_dl_loaded_modules) : 0; /* Some flavors of SVr4 do not generate the R_*_COPY directive, and we have to manually search for entries that require fixups. Solaris gets this one right, from what I understand. */ #ifdef DL_DEBUG _dl_dprintf(2, "Beginning copy fixups\n"); #endif if (_dl_symbol_tables) goof += _dl_copy_fixups(_dl_symbol_tables); #ifdef DL_TRACE if (goof || _dl_trace_loaded_objects) _dl_exit(0); #endif /* OK, at this point things are pretty much ready to run. Now we need to touch up a few items that are required, and then we can let the user application have at it. Note that the dynamic linker itself is not guaranteed to be fully dynamicly linked if we are using ld.so.1, so we have to look up each symbol individually. */ _dl_brkp = (unsigned long *) _dl_find_hash("___brk_addr", NULL, 1, NULL, 0); if (_dl_brkp) { *_dl_brkp = brk_addr; } _dl_envp = (unsigned long *) _dl_find_hash("__environ", NULL, 1, NULL, 0); if (_dl_envp) { *_dl_envp = (unsigned long) envp; } #ifdef DO_MPROTECT_HACKS { int i; elf_phdr *ppnt; /* We had to set the protections of all pages to R/W for dynamic linking. Set text pages back to R/O */ for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) { for (ppnt = tpnt->ppnt, i = 0; i < tpnt->n_phent; i++, ppnt++) { if (ppnt->p_type == PT_LOAD && !(ppnt->p_flags & PF_W) && tpnt->dynamic_info[DT_TEXTREL]) { _dl_mprotect((void *) (tpnt->loadaddr + (ppnt->p_vaddr & 0xfffff000)), (ppnt->p_vaddr & 0xfff) + (unsigned long) ppnt->p_filesz, LXFLAGS(ppnt->p_flags)); } } } } #endif _dl_atexit = (int (*)(void *)) _dl_find_hash("atexit", NULL, 1, NULL, 0); /* * OK, fix one more thing - set up the debug_addr structure to point * to our chain. Later we may need to fill in more fields, but this * should be enough for now. */ debug_addr->r_map = (struct link_map *) _dl_loaded_modules; debug_addr->r_version = 1; debug_addr->r_ldbase = load_addr; debug_addr->r_brk = (unsigned long) &_dl_debug_state; _dl_debug_addr = debug_addr; debug_addr->r_state = RT_CONSISTENT; /* This is written in this funny way to keep gcc from inlining the function call. */ ((void (*)(void)) debug_addr->r_brk) (); #ifdef DL_DEBUG _dl_dprintf(2, "Calling init/fini for shared libraries\n"); #endif for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) { /* Apparently crt1 for the application is responsible for handling this. * We only need to run the init/fini for shared libraries */ if (tpnt->libtype == program_interpreter || tpnt->libtype == elf_executable) continue; if (tpnt->init_flag & INIT_FUNCS_CALLED) continue; tpnt->init_flag |= INIT_FUNCS_CALLED; if (tpnt->dynamic_info[DT_INIT]) { _dl_elf_init = (int (*)(void)) (tpnt->loadaddr + tpnt->dynamic_info[DT_INIT]); (*_dl_elf_init) (); } if (_dl_atexit && tpnt->dynamic_info[DT_FINI]) { (*_dl_atexit) (tpnt->loadaddr + tpnt->dynamic_info[DT_FINI]); } #ifdef DL_DEBUG else { if (!_dl_atexit) _dl_dprintf(2, "%s: The address of atexit () is 0x0.\n", tpnt->libname); #if 0 if (!tpnt->dynamic_info[DT_FINI]) _dl_dprintf(2, "%s: Invalid .fini section.\n", tpnt->libname); #endif } #endif } } /* * This stub function is used by some debuggers. The idea is that they * can set an internal breakpoint on it, so that we are notified when the * address mapping is changed in some way. */ void _dl_debug_state() { return; } int _dl_fixup(struct elf_resolve *tpnt) { int goof = 0; if (tpnt->next) goof += _dl_fixup(tpnt->next); if (tpnt->dynamic_info[DT_REL]) { #ifdef ELF_USES_RELOCA _dl_dprintf(2, "%s: can't handle REL relocation records\n", _dl_progname); _dl_exit(17); #else if (tpnt->init_flag & RELOCS_DONE) return goof; tpnt->init_flag |= RELOCS_DONE; goof += _dl_parse_relocation_information(tpnt, tpnt->dynamic_info[DT_REL], tpnt->dynamic_info[DT_RELSZ], 0); #endif } if (tpnt->dynamic_info[DT_RELA]) { #ifdef ELF_USES_RELOCA if (tpnt->init_flag & RELOCS_DONE) return goof; tpnt->init_flag |= RELOCS_DONE; goof += _dl_parse_relocation_information(tpnt, tpnt->dynamic_info[DT_RELA], tpnt->dynamic_info[DT_RELASZ], 0); #else _dl_dprintf(2, "%s: can't handle RELA relocation records\n", _dl_progname); _dl_exit(18); #endif } if (tpnt->dynamic_info[DT_JMPREL]) { if (tpnt->init_flag & JMP_RELOCS_DONE) return goof; tpnt->init_flag |= JMP_RELOCS_DONE; if (!_dl_not_lazy || *_dl_not_lazy == 0) _dl_parse_lazy_relocation_information(tpnt, tpnt->dynamic_info[DT_JMPREL], tpnt->dynamic_info [DT_PLTRELSZ], 0); else goof += _dl_parse_relocation_information(tpnt, tpnt->dynamic_info[DT_JMPREL], tpnt->dynamic_info[DT_PLTRELSZ], 0); } return goof; } void *_dl_malloc(int size) { void *retval; #if 0 //#ifdef DL_DEBUG _dl_dprintf(2, "malloc: request for %d bytes\n", size); #endif if (_dl_malloc_function) return (*_dl_malloc_function) (size); if (_dl_malloc_addr - _dl_mmap_zero + size > 4096) { #ifdef DL_DEBUG _dl_dprintf(2, "malloc: mmapping more memory\n"); #endif _dl_mmap_zero = _dl_malloc_addr = _dl_mmap((void *) 0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); if (_dl_mmap_check_error(_dl_mmap_zero)) { _dl_dprintf(2, "%s: mmap of a spare page failed!\n", _dl_progname); _dl_exit(20); } } retval = _dl_malloc_addr; _dl_malloc_addr += size; /* * Align memory to 4 byte boundary. Some platforms require this, others * simply get better performance. */ _dl_malloc_addr = (char *) (((unsigned long) _dl_malloc_addr + 3) & ~(3)); return retval; } char *_dl_getenv(char *symbol, char **envp) { char *pnt; char *pnt1; while ((pnt = *envp++)) { pnt1 = symbol; while (*pnt && *pnt == *pnt1) pnt1++, pnt++; if (!*pnt || *pnt != '=' || *pnt1) continue; return pnt + 1; } return 0; } void _dl_unsetenv(char *symbol, char **envp) { char *pnt; char *pnt1; char **newenvp = envp; for (pnt = *envp; pnt; pnt = *++envp) { pnt1 = symbol; while (*pnt && *pnt == *pnt1) pnt1++, pnt++; if (!*pnt || *pnt != '=' || *pnt1) *newenvp++ = *envp; } *newenvp++ = *envp; return; } char *_dl_strdup(const char *string) { char *retval; int len; len = _dl_strlen(string); retval = _dl_malloc(len + 1); _dl_strcpy(retval, string); return retval; } /* Minimal printf which handles only %s, %d, and %x */ void _dl_dprintf(int fd, const char *fmt, ...) { int num; va_list args; char *start, *ptr, *string; char buf[2048]; start = ptr = buf; if (!fmt) return; if (_dl_strlen(fmt) >= (sizeof(buf) - 1)) _dl_write(fd, "(overflow)\n", 10); _dl_strcpy(buf, fmt); va_start(args, fmt); while (start) { while (*ptr != '%' && *ptr) { ptr++; } if (*ptr == '%') { *ptr++ = '\0'; _dl_write(fd, start, _dl_strlen(start)); switch (*ptr++) { case 's': string = va_arg(args, char *); if (!string) _dl_write(fd, "(null)", 6); else _dl_write(fd, string, _dl_strlen(string)); break; case 'i': case 'd': { char tmp[22]; num = va_arg(args, int); string = _dl_simple_ltoa(tmp, num); _dl_write(fd, string, _dl_strlen(string)); break; } case 'x': case 'X': { char tmp[22]; num = va_arg(args, int); string = _dl_simple_ltoahex(tmp, num); _dl_write(fd, string, _dl_strlen(string)); break; } default: _dl_write(fd, "(null)", 6); break; } start = ptr; } else { _dl_write(fd, start, _dl_strlen(start)); start = NULL; } } return; } #include "hash.c" #include "readelflib1.c"