dl-elf.c

Axis 221 camera embedded programing interface

/* vi: set sw=4 ts=4: */
/*
 * This file contains the helper routines to load an ELF shared
 * library into memory and add the symbol table info to the chain.
 *
 * Copyright (C) 2000-2004 by Erik Andersen <[e-mail]>
 * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
 *				David Engel, Hongjiu Lu and Mitch D'Souza
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the above contributors may not be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */


#include "ldso.h"

#ifdef __LDSO_CACHE_SUPPORT__

static caddr_t _dl_cache_addr = NULL;
static size_t _dl_cache_size = 0;

int _dl_map_cache(void)
{
	int fd;
	struct stat st;
	header_t *header;
	libentry_t *libent;
	int i, strtabsize;

	if (_dl_cache_addr == (caddr_t) - 1)
		return -1;
	else if (_dl_cache_addr != NULL)
		return 0;

	if (_dl_stat(LDSO_CACHE, &st)
	    || (fd = _dl_open(LDSO_CACHE, O_RDONLY, 0)) < 0) {
		_dl_cache_addr = (caddr_t) - 1;	/* so we won't try again */
		return -1;
	}

	_dl_cache_size = st.st_size;
	_dl_cache_addr = (caddr_t) _dl_mmap(0, _dl_cache_size, PROT_READ, MAP_SHARED, fd, 0);
	_dl_close(fd);
	if (_dl_mmap_check_error(_dl_cache_addr)) {
		_dl_dprintf(2, "%s: can't map cache '%s'\n",
				_dl_progname, LDSO_CACHE);
		return -1;
	}

	header = (header_t *) _dl_cache_addr;

	if (_dl_cache_size < sizeof(header_t) ||
			_dl_memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN)
			|| _dl_memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN)
			|| _dl_cache_size <
			(sizeof(header_t) + header->nlibs * sizeof(libentry_t))
			|| _dl_cache_addr[_dl_cache_size - 1] != '\0')
	{
		_dl_dprintf(2, "%s: cache '%s' is corrupt\n", _dl_progname,
				LDSO_CACHE);
		goto fail;
	}

	strtabsize = _dl_cache_size - sizeof(header_t) -
		header->nlibs * sizeof(libentry_t);
	libent = (libentry_t *) & header[1];

	for (i = 0; i < header->nlibs; i++) {
		if (libent[i].sooffset >= strtabsize ||
				libent[i].liboffset >= strtabsize)
		{
			_dl_dprintf(2, "%s: cache '%s' is corrupt\n", _dl_progname, LDSO_CACHE);
			goto fail;
		}
	}

	return 0;

fail:
	_dl_munmap(_dl_cache_addr, _dl_cache_size);
	_dl_cache_addr = (caddr_t) - 1;
	return -1;
}

int _dl_unmap_cache(void)
{
	if (_dl_cache_addr == NULL || _dl_cache_addr == (caddr_t) - 1)
		return -1;

#if 1
	_dl_munmap(_dl_cache_addr, _dl_cache_size);
	_dl_cache_addr = NULL;
#endif

	return 0;
}
#endif


void 
_dl_protect_relro (struct elf_resolve *l)
{
	ElfW(Addr) start = ((l->loadaddr + l->relro_addr)
			    & ~(_dl_pagesize - 1));
	ElfW(Addr) end = ((l->loadaddr + l->relro_addr + l->relro_size)
			  & ~(_dl_pagesize - 1));
#if defined (__SUPPORT_LD_DEBUG__)
	if (_dl_debug)
		_dl_dprintf(2, "RELRO protecting %s:  start:%x, end:%x\n", l->libname, start, end);
#endif
	if (start != end &&
	    _dl_mprotect ((void *) start, end - start, PROT_READ) < 0) {
		_dl_dprintf(2, "%s: cannot apply additional memory protection after relocation", l->libname);
		_dl_exit(0);
	}
}

/* This function's behavior must exactly match that
 * in uClibc/ldso/util/ldd.c */
static struct elf_resolve *
search_for_named_library(const char *name, int secure, const char *path_list,
	struct dyn_elf **rpnt)
{
	int i, count = 1;
	char *path, *path_n;
	char mylibname[2050];
	struct elf_resolve *tpnt1;

	if (path_list==NULL)
		return NULL;

	/* We need a writable copy of this string */
	path = _dl_strdup(path_list);
	if (!path) {
		_dl_dprintf(2, "Out of memory!\n");
		_dl_exit(0);
	}


	/* Unlike ldd.c, don't bother to eliminate double //s */


	/* Replace colons with zeros in path_list and count them */
	for(i=_dl_strlen(path); i > 0; i--) {
		if (path[i]==':') {
			path[i]=0;
			count++;
		}
	}

	path_n = path;
	for (i = 0; i < count; i++) {
		_dl_strcpy(mylibname, path_n);
		_dl_strcat(mylibname, "/");
		_dl_strcat(mylibname, name);
		if ((tpnt1 = _dl_load_elf_shared_library(secure, rpnt, mylibname)) != NULL)
		{
			return tpnt1;
		}
		path_n += (_dl_strlen(path_n) + 1);
	}
	return NULL;
}

/* Check if the named library is already loaded... */
struct elf_resolve *_dl_check_if_named_library_is_loaded(const char *full_libname,
		int trace_loaded_objects)
{
	const char *pnt, *pnt1;
	struct elf_resolve *tpnt1;
	const char *libname, *libname2;
	static const char libc[] = "libc.so.";
	static const char aborted_wrong_lib[] = "%s: aborted attempt to load %s!\n";

	pnt = libname = full_libname;

#if defined (__SUPPORT_LD_DEBUG__)
	if(_dl_debug)
		_dl_dprintf(_dl_debug_file, "Checking if '%s' is already loaded\n", full_libname);
#endif
	/* quick hack to ensure mylibname buffer doesn't overflow.  don't
	   allow full_libname or any directory to be longer than 1024. */
	if (_dl_strlen(full_libname) > 1024)
		return NULL;

	/* Skip over any initial initial './' and '/' stuff to
	 * get the short form libname with no path garbage */
	pnt1 = _dl_strrchr(pnt, '/');
	if (pnt1) {
		libname = pnt1 + 1;
	}

	/* Make sure they are not trying to load the wrong C library!
	 * This sometimes happens esp with shared libraries when the
	 * library path is somehow wrong! */
#define isdigit(c)  (c >= '0' && c <= '9')
	if ((_dl_strncmp(libname, libc, 8) == 0) &&  _dl_strlen(libname) >=8 &&
			isdigit(libname[8]))
	{
		/* Abort attempts to load glibc, libc5, etc */
		if ( libname[8]!='0') {
			if (!trace_loaded_objects) {
				_dl_dprintf(2, aborted_wrong_lib, libname, _dl_progname);
				_dl_exit(1);
			}
			return NULL;
		}
	}

	/* Critical step!  Weed out duplicates early to avoid
	 * function aliasing, which wastes memory, and causes
	 * really bad things to happen with weaks and globals. */
	for (tpnt1 = _dl_loaded_modules; tpnt1; tpnt1 = tpnt1->next) {

		/* Skip over any initial initial './' and '/' stuff to
		 * get the short form libname with no path garbage */
		libname2 = tpnt1->libname;
		pnt1 = _dl_strrchr(libname2, '/');
		if (pnt1) {
			libname2 = pnt1 + 1;
		}

		if (_dl_strcmp(libname2, libname) == 0) {
			/* Well, that was certainly easy */
			return tpnt1;
		}
	}

	return NULL;
}


/* Used to return error codes back to dlopen et. al.  */
unsigned long _dl_error_number;
unsigned long _dl_internal_error_number;

struct elf_resolve *_dl_load_shared_library(int secure, struct dyn_elf **rpnt,
	struct elf_resolve *tpnt, char *full_libname, int __attribute__((unused)) trace_loaded_objects)
{
	char *pnt, *pnt1;
	struct elf_resolve *tpnt1;
	char *libname;

	_dl_internal_error_number = 0;
	libname = full_libname;

	/* quick hack to ensure mylibname buffer doesn't overflow.  don't
	   allow full_libname or any directory to be longer than 1024. */
	if (_dl_strlen(full_libname) > 1024)
		goto goof;

	/* Skip over any initial initial './' and '/' stuff to
	 * get the short form libname with no path garbage */
	pnt1 = _dl_strrchr(libname, '/');
	if (pnt1) {
		libname = pnt1 + 1;
	}
#if 0
	/* Critical step!  Weed out duplicates early to avoid
	 * function aliasing, which wastes memory, and causes
	 * really bad things to happen with weaks and globals. */
	if ((tpnt1=_dl_check_if_named_library_is_loaded(libname, trace_loaded_objects))!=NULL)
		return tpnt1;
#endif

#if defined (__SUPPORT_LD_DEBUG__)
	if(_dl_debug) _dl_dprintf(_dl_debug_file, "\tfind library='%s'; searching\n", libname);
#endif
	/* If the filename has any '/', try it straight and leave it at that.
	   For IBCS2 compatibility under linux, we substitute the string
	   /usr/i486-sysv4/lib for /usr/lib in library names. */

	if (libname != full_libname) {
#if defined (__SUPPORT_LD_DEBUG__)
		if(_dl_debug) _dl_dprintf(_dl_debug_file, "\ttrying file='%s'\n", full_libname);
#endif
		tpnt1 = _dl_load_elf_shared_library(secure, rpnt, full_libname);
		if (tpnt1) {
			return tpnt1;
		}
		//goto goof;
	}

	/*
	 * The ABI specifies that RPATH is searched before LD_*_PATH or
	 * the default path of /usr/lib.  Check in rpath directories.
	 */
	for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) {
		if (tpnt->libtype == elf_executable) {
			pnt = (char *) tpnt->dynamic_info[DT_RPATH];
			if (pnt) {
				pnt += (unsigned long) tpnt->loadaddr + tpnt->dynamic_info[DT_STRTAB];
#if defined (__SUPPORT_LD_DEBUG__)
				if(_dl_debug) _dl_dprintf(_dl_debug_file, "\tsearching RPATH='%s'\n", pnt);
#endif
				if ((tpnt1 = search_for_named_library(libname, secure, pnt, rpnt)) != NULL)
				{
					return tpnt1;
				}
			}
		}
	}

	/* Check in LD_{ELF_}LIBRARY_PATH, if specified and allowed */
	if (_dl_library_path) {
#if defined (__SUPPORT_LD_DEBUG__)
		if(_dl_debug) _dl_dprintf(_dl_debug_file, "\tsearching LD_LIBRARY_PATH='%s'\n", _dl_library_path);
#endif
		if ((tpnt1 = search_for_named_library(libname, secure, _dl_library_path, rpnt)) != NULL)
		{
			return tpnt1;
		}
	}

	/*
	 * Where should the cache be searched?  There is no such concept in the
	 * ABI, so we have some flexibility here.  For now, search it before
	 * the hard coded paths that follow (i.e before /lib and /usr/lib).
	 */
#ifdef __LDSO_CACHE_SUPPORT__
	if (_dl_cache_addr != NULL && _dl_cache_addr != (caddr_t) - 1) {
		int i;
		header_t *header = (header_t *) _dl_cache_addr;
		libentry_t *libent = (libentry_t *) & header[1];
		char *strs = (char *) &libent[header->nlibs];

#if defined (__SUPPORT_LD_DEBUG__)
		if(_dl_debug) _dl_dprintf(_dl_debug_file, "\tsearching cache='%s'\n", LDSO_CACHE);
#endif
		for (i = 0; i < header->nlibs; i++) {
			if ((libent[i].flags == LIB_ELF ||
						libent[i].flags == LIB_ELF_LIBC0 ||
						libent[i].flags == LIB_ELF_LIBC5) &&
					_dl_strcmp(libname, strs + libent[i].sooffset) == 0 &&
					(tpnt1 = _dl_load_elf_shared_library(secure,
														 rpnt, strs + libent[i].liboffset)))
				return tpnt1;
		}
	}
#endif

	/* Look for libraries wherever the shared library loader
	 * was installed */
#if defined (__SUPPORT_LD_DEBUG__)
	if(_dl_debug) _dl_dprintf(_dl_debug_file, "\tsearching ldso dir='%s'\n", _dl_ldsopath);
#endif
	if ((tpnt1 = search_for_named_library(libname, secure, _dl_ldsopath, rpnt)) != NULL)
	{
		return tpnt1;
	}


	/* Lastly, search the standard list of paths for the library.
	   This list must exactly match the list in uClibc/ldso/util/ldd.c */
#if defined (__SUPPORT_LD_DEBUG__)
	if(_dl_debug) _dl_dprintf(_dl_debug_file, "\tsearching full lib path list\n");
#endif
	if ((tpnt1 = search_for_named_library(libname, secure,
					UCLIBC_RUNTIME_PREFIX "lib:"
					UCLIBC_RUNTIME_PREFIX "usr/lib"
#ifndef __LDSO_CACHE_SUPPORT__
					":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib"
#endif
					, rpnt)
		) != NULL)
	{
		return tpnt1;
	}

goof:
	/* Well, we shot our wad on that one.  All we can do now is punt */
	if (_dl_internal_error_number)
		_dl_error_number = _dl_internal_error_number;
	else
		_dl_error_number = LD_ERROR_NOFILE;
#if defined (__SUPPORT_LD_DEBUG__)
	if(_dl_debug) _dl_dprintf(2, "Bummer: could not find '%s'!\n", libname);
#endif
	return NULL;
}


/*
 * Read one ELF library into memory, mmap it into the correct locations and
 * add the symbol info to the symbol chain.  Perform any relocations that
 * are required.
 */

struct elf_resolve *_dl_load_elf_shared_library(int secure,
	struct dyn_elf **rpnt, char *libname)
{
	ElfW(Ehdr) *epnt;
	unsigned long dynamic_addr = 0;
	Elf32_Dyn *dpnt;
	struct elf_resolve *tpnt;
	ElfW(Phdr) *ppnt;
	char *status, *header;
	unsigned long dynamic_info[DYNAMIC_SIZE];
	unsigned long *lpnt;
	unsigned long libaddr;
	unsigned long minvma = 0xffffffff, maxvma = 0;
	int i, flags, piclib, infile;
	ElfW(Addr) relro_addr = 0;
	size_t relro_size = 0;

	/* If this file is already loaded, skip this step */
	tpnt = _dl_check_hashed_files(libname);
	if (tpnt) {
		if (*rpnt) {
			(*rpnt)->next = (struct dyn_elf *) _dl_malloc(sizeof(struct dyn_elf));
			_dl_memset((*rpnt)->next, 0, sizeof(struct dyn_elf));
			(*rpnt)->next->prev = (*rpnt);
			*rpnt = (*rpnt)->next;
			(*rpnt)->dyn = tpnt;
			tpnt->symbol_scope = _dl_symbol_tables;
		}
		tpnt->usage_count++;
		tpnt->libtype = elf_lib;
#if defined (__SUPPORT_LD_DEBUG__)
		if(_dl_debug) _dl_dprintf(2, "file='%s';  already loaded\n", libname);
#endif
		return tpnt;
	}

	/* If we are in secure mode (i.e. a setu/gid binary using LD_PRELOAD),
	   we don't load the library if it isn't setuid. */

	if (secure) {
		struct stat st;

		if (_dl_stat(libname, &st) || !(st.st_mode & S_ISUID))
			return NULL;
	}