diff options
Diffstat (limited to 'utils/ldd.c')
| -rw-r--r-- | utils/ldd.c | 664 |
1 files changed, 664 insertions, 0 deletions
diff --git a/utils/ldd.c b/utils/ldd.c new file mode 100644 index 000000000..3ea41b424 --- /dev/null +++ b/utils/ldd.c @@ -0,0 +1,664 @@ +/* vi: set sw=4 ts=4: */ +/* + * A small little ldd implementation for uClibc + * + * Copyright (C) 2000 by Lineo, inc and Erik Andersen + * Copyright (C) 2000-2002 Erik Andersen <andersee@debian.org> + * + * Several functions in this file (specifically, elf_find_section_type(), + * elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from + * elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser + * <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC + * (GPL2). + * + * 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 of the License, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ + + +#define _GNU_SOURCE +#include <stdlib.h> +#include <stdio.h> +#include <fcntl.h> +#include <string.h> +#include <unistd.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/types.h> +#include <sys/wait.h> + +#include "bswap.h" +#if defined (sun) +#include "link.h" +#else +#include "elf.h" +#endif + +#ifdef DMALLOC +#include <dmalloc.h> +#endif + +#if defined(__arm__) +#define MATCH_MACHINE(x) (x == EM_ARM) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined(__s390__) +#define MATCH_MACHINE(x) (x == EM_S390) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined(__i386__) +#ifndef EM_486 +#define MATCH_MACHINE(x) (x == EM_386) +#else +#define MATCH_MACHINE(x) (x == EM_386 || x == EM_486) +#endif +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined(__mc68000__) +#define MATCH_MACHINE(x) (x == EM_68K) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined(__mips__) +#define MATCH_MACHINE(x) (x == EM_MIPS || x == EM_MIPS_RS3_LE) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined(__powerpc__) +#define MATCH_MACHINE(x) (x == EM_PPC) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined(__sh__) +#define MATCH_MACHINE(x) (x == EM_SH) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined (__v850e__) +#define MATCH_MACHINE(x) ((x) == EM_V850 || (x) == EM_CYGNUS_V850) +#define ELFCLASSM ELFCLASS32 +#endif + +#if defined (__sparc__) +#define MATCH_MACHINE(x) ((x) == EM_SPARC || (x) == EM_SPARC32PLUS) +#define ELFCLASSM ELFCLASS32 +#endif + + +#ifndef MATCH_MACHINE +#warning "You really should add a MATCH_MACHINE() macro for your architecture" +#endif + +#if __BYTE_ORDER == __LITTLE_ENDIAN +#define ELFDATAM ELFDATA2LSB +#elif __BYTE_ORDER == __BIG_ENDIAN +#define ELFDATAM ELFDATA2MSB +#endif + +struct library { + char *name; + int resolved; + char *path; + struct library *next; +}; +struct library *lib_list = NULL; +char not_found[] = "not found"; +char *interp = NULL; +char *interp_dir = NULL; +int byteswap; +static int interpreter_already_found=0; + +inline uint32_t byteswap32_to_host(uint32_t value) +{ + if (byteswap==1) { + return(bswap_32(value)); + } else { + return(value); + } +} + + + +Elf32_Shdr * elf_find_section_type( int key, Elf32_Ehdr *ehdr) +{ + int j; + Elf32_Shdr *shdr; + shdr = (Elf32_Shdr *)(ehdr->e_shoff + (char *)ehdr); + for (j = ehdr->e_shnum; --j>=0; ++shdr) { + if (key==(int)byteswap32_to_host(shdr->sh_type)) { + return shdr; + } + } + return NULL; +} + +Elf32_Phdr * elf_find_phdr_type( int type, Elf32_Ehdr *ehdr) +{ + int j; + Elf32_Phdr *phdr = (Elf32_Phdr *)(ehdr->e_phoff + (char *)ehdr); + for (j = ehdr->e_phnum; --j>=0; ++phdr) { + if (type==(int)byteswap32_to_host(phdr->p_type)) { + return phdr; + } + } + return NULL; +} + +/* Returns value if return_val==1, ptr otherwise */ +void * elf_find_dynamic(int const key, Elf32_Dyn *dynp, + Elf32_Ehdr *ehdr, int return_val) +{ + Elf32_Phdr *pt_text = elf_find_phdr_type(PT_LOAD, ehdr); + unsigned tx_reloc = byteswap32_to_host(pt_text->p_vaddr) - byteswap32_to_host(pt_text->p_offset); + for (; DT_NULL!=byteswap32_to_host(dynp->d_tag); ++dynp) { + if (key == (int)byteswap32_to_host(dynp->d_tag)) { + if (return_val == 1) + return (void *)(intptr_t)byteswap32_to_host(dynp->d_un.d_val); + else + return (void *)(byteswap32_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr ); + } + } + return NULL; +} + +int check_elf_header(Elf32_Ehdr *const ehdr) +{ + if (! ehdr || strncmp((void *)ehdr, ELFMAG, SELFMAG) != 0 || + ehdr->e_ident[EI_CLASS] != ELFCLASS32 || + ehdr->e_ident[EI_VERSION] != EV_CURRENT) + { + return 1; + } + + /* Check if the target endianness matches the host's endianness */ + byteswap = 0; +#if __BYTE_ORDER == __LITTLE_ENDIAN + if (ehdr->e_ident[5] == ELFDATA2MSB) { + /* Ick -- we will have to byte-swap everything */ + byteswap = 1; + } +#elif __BYTE_ORDER == __BIG_ENDIAN + if (ehdr->e_ident[5] == ELFDATA2LSB) { + /* Ick -- we will have to byte-swap everything */ + byteswap = 1; + } +#else +#error Unknown host byte order! +#endif + + /* Be vary lazy, and only byteswap the stuff we use */ + if (byteswap==1) { + ehdr->e_type=bswap_16(ehdr->e_type); + ehdr->e_phoff=bswap_32(ehdr->e_phoff); + ehdr->e_shoff=bswap_32(ehdr->e_shoff); + ehdr->e_phnum=bswap_16(ehdr->e_phnum); + ehdr->e_shnum=bswap_16(ehdr->e_shnum); + } + + return 0; +} + +/* This function's behavior must exactly match that + * in uClibc/ldso/ldso/readelflib1.c */ +static void search_for_named_library(char *name, char *result, const char *path_list) +{ + int i, count = 1; + char *path, *path_n; + struct stat filestat; + + /* We need a writable copy of this string */ + path = strdup(path_list); + if (!path) { + fprintf(stderr, "Out of memory!\n"); + exit(EXIT_FAILURE); + } + /* Eliminate all double //s */ + path_n=path; + while((path_n=strstr(path_n, "//"))) { + i = strlen(path_n); + memmove(path_n, path_n+1, i-1); + *(path_n + i - 1)='\0'; + } + + /* Replace colons with zeros in path_list and count them */ + for(i=strlen(path); i > 0; i--) { + if (path[i]==':') { + path[i]=0; + count++; + } + } + path_n = path; + for (i = 0; i < count; i++) { + strcpy(result, path_n); + strcat(result, "/"); + strcat(result, name); + if (stat (result, &filestat) == 0 && filestat.st_mode & S_IRUSR) { + free(path); + return; + } + path_n += (strlen(path_n) + 1); + } + free(path); + *result = '\0'; +} + +void locate_library_file(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, int is_suid, struct library *lib) +{ + char *buf; + char *path; + struct stat filestat; + + /* If this is a fully resolved name, our job is easy */ + if (stat (lib->name, &filestat) == 0) { + lib->path = lib->name; + return; + } + + /* We need some elbow room here. Make some room...*/ + buf = malloc(1024); + if (!buf) { + fprintf(stderr, "Out of memory!\n"); + exit(EXIT_FAILURE); + } + + /* This function must match the behavior of _dl_load_shared_library + * in readelflib1.c or things won't work out as expected... */ + + /* The ABI specifies that RPATH is searched first, so do that now. */ + path = (char *)elf_find_dynamic(DT_RPATH, dynamic, ehdr, 0); + if (path) { + search_for_named_library(lib->name, buf, path); + if (*buf != '\0') { + lib->path = buf; + return; + } + } + + /* Next check LD_{ELF_}LIBRARY_PATH if specified and allowed. + * Since this app doesn't actually run an executable I will skip + * the suid check, and just use LD_{ELF_}LIBRARY_PATH if set */ + if (is_suid==1) + path = NULL; + else + path = getenv("LD_LIBRARY_PATH"); + if (path) { + search_for_named_library(lib->name, buf, path); + if (*buf != '\0') { + lib->path = buf; + return; + } + } + +#ifdef USE_CACHE + /* FIXME -- add code to check the Cache here */ +#endif + + + /* Next look for libraries wherever the shared library + * loader was installed -- this is usually where we + * should find things... */ + if (interp_dir) { + search_for_named_library(lib->name, buf, interp_dir); + if (*buf != '\0') { + lib->path = buf; + return; + } + } + + /* Lastly, search the standard list of paths for the library. + This list must exactly match the list in uClibc/ldso/ldso/readelflib1.c */ + path = UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib:" + UCLIBC_RUNTIME_PREFIX "usr/lib:" + UCLIBC_RUNTIME_PREFIX "lib:" + "/usr/lib:" + "/lib"; + search_for_named_library(lib->name, buf, path); + if (*buf != '\0') { + lib->path = buf; + } else { + free(buf); + lib->path = not_found; + } +} + +static int add_library(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, int is_setuid, char *s) +{ + char *tmp, *tmp1, *tmp2; + struct library *cur, *newlib=lib_list; + + if (!s || !strlen(s)) + return 1; + + tmp = s; + while (*tmp) { + if (*tmp == '/') + s = tmp + 1; + tmp++; + } + + /* We add libc.so.0 elsewhere */ + if (interpreter_already_found && (tmp=strrchr(interp, '/')) != NULL) + { + int len = strlen(interp_dir); + if (strcmp(s, interp+1+len)==0) + return 1; + } + + for (cur = lib_list; cur; cur=cur->next) { + /* Check if this library is already in the list */ + tmp1 = tmp2 = cur->name; + while (*tmp1) { + if (*tmp1 == '/') + tmp2 = tmp1 + 1; + tmp1++; + } + if(strcmp(tmp2, s)==0) { + //printf("find_elf_interpreter is skipping '%s' (already in list)\n", cur->name); + return 0; + } + } + + /* Ok, this lib needs to be added to the list */ + newlib = malloc(sizeof(struct library)); + if (!newlib) + return 1; + newlib->name = malloc(strlen(s)+1); + strcpy(newlib->name, s); + newlib->resolved = 0; + newlib->path = NULL; + newlib->next = NULL; + + /* Now try and locate where this library might be living... */ + locate_library_file(ehdr, dynamic, is_setuid, newlib); + + //printf("add_library is adding '%s' to '%s'\n", newlib->name, newlib->path); + if (!lib_list) { + lib_list = newlib; + } else { + for (cur = lib_list; cur->next; cur=cur->next); /* nothing */ + cur->next = newlib; + } + return 0; +} + + +static void find_needed_libraries(Elf32_Ehdr* ehdr, Elf32_Dyn* dynamic, char *strtab, int is_setuid) +{ + Elf32_Dyn *dyns; + + for (dyns=dynamic; byteswap32_to_host(dyns->d_tag)!=DT_NULL; ++dyns) { + if (DT_NEEDED == byteswap32_to_host(dyns->d_tag)) { + add_library(ehdr, dynamic, is_setuid, + (char*)strtab + byteswap32_to_host(dyns->d_un.d_val)); + } + } +} + +static struct library * find_elf_interpreter(Elf32_Ehdr* ehdr) +{ + Elf32_Phdr *phdr; + + if (interpreter_already_found==1) + return NULL; + phdr = elf_find_phdr_type(PT_INTERP, ehdr); + if (phdr) { + struct library *cur, *newlib=NULL; + char *s = (char*)ehdr + byteswap32_to_host(phdr->p_offset); + + char *tmp, *tmp1; + interp = strdup(s); + interp_dir = strdup(s); + tmp = strrchr(interp_dir, '/'); + if (*tmp) + *tmp = '\0'; + else { + free(interp_dir); + interp_dir = interp; + } + tmp1 = tmp = s; + while (*tmp) { + if (*tmp == '/') + tmp1 = tmp + 1; + tmp++; + } + for (cur = lib_list; cur; cur=cur->next) { + /* Check if this library is already in the list */ + if(strcmp(cur->name, tmp1)==0) { + //printf("find_elf_interpreter is replacing '%s' (already in list)\n", cur->name); + newlib = cur; + free(newlib->name); + free(newlib->path); + return NULL; + } + } + if (newlib == NULL) + newlib = malloc(sizeof(struct library)); + if (!newlib) + return NULL; + newlib->name = malloc(strlen(s)+1); + strcpy(newlib->name, s); + newlib->path = newlib->name; + newlib->resolved = 1; + newlib->next = NULL; + +#if 0 + //printf("find_elf_interpreter is adding '%s' to '%s'\n", newlib->name, newlib->path); + if (!lib_list) { + lib_list = newlib; + } else { + for (cur = lib_list; cur->next; cur=cur->next); /* nothing */ + cur->next = newlib; + } +#endif + interpreter_already_found=1; + return newlib; + } + return NULL; +} + +/* map the .so, and locate interesting pieces */ +int find_dependancies(char* filename) +{ + int is_suid = 0; + FILE *thefile; + struct stat statbuf; + char *dynstr=NULL; + Elf32_Ehdr *ehdr = NULL; + Elf32_Shdr *dynsec = NULL; + Elf32_Dyn *dynamic = NULL; + struct library *interp; + + if (filename == not_found) + return 0; + + if (!filename) { + fprintf(stderr, "No filename specified.\n"); + return -1; + } + if (!(thefile = fopen(filename, "r"))) { + perror(filename); + return -1; + } + if (fstat(fileno(thefile), &statbuf) < 0) { + perror(filename); + return -1; + } + + if ((size_t)statbuf.st_size < sizeof(Elf32_Ehdr)) + goto foo; + + if (!S_ISREG(statbuf.st_mode)) + goto foo; + + /* mmap the file to make reading stuff from it effortless */ + ehdr = (Elf32_Ehdr *)mmap(0, statbuf.st_size, + PROT_READ|PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0); + +foo: + /* Check if this looks like a legit ELF file */ + if (check_elf_header(ehdr)) { + fprintf(stderr, "%s: not an ELF file.\n", filename); + return -1; + } + /* Check if this is the right kind of ELF file */ + if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) { + fprintf(stderr, "%s: not a dynamic executable\n", filename); + return -1; + } + if (ehdr->e_type == ET_EXEC) { + if (statbuf.st_mode & S_ISUID) + is_suid = 1; + if ((statbuf.st_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) + is_suid = 1; + /* FIXME */ + if (is_suid) + fprintf(stderr, "%s: is setuid\n", filename); + } + + interpreter_already_found=0; + interp = find_elf_interpreter(ehdr); + +#ifdef __LDSO_LDD_SUPPORT + if (interp && ehdr->e_type == ET_EXEC && ehdr->e_ident[EI_CLASS] == ELFCLASSM && + ehdr->e_ident[EI_DATA] == ELFDATAM + && ehdr->e_ident[EI_VERSION] == EV_CURRENT && MATCH_MACHINE(ehdr->e_machine)) + { + struct stat statbuf; + if (stat(interp->path, &statbuf) == 0 && S_ISREG(statbuf.st_mode)) { + pid_t pid; + int status; + static const char * const environment[] = { + "PATH=/usr/bin:/bin:/usr/sbin:/sbin", + "SHELL=/bin/sh", + "LD_TRACE_LOADED_OBJECTS=1", + NULL + }; + + if ((pid = fork()) == 0) { + /* Cool, it looks like we should be able to actually + * run this puppy. Do so now... */ + execle(filename, filename, NULL, environment); + _exit(0xdead); + } + + /* Wait till it returns */ + waitpid(pid, &status, 0); + if (WIFEXITED(status) && WEXITSTATUS(status)==0) { + return 1; + } + + /* If the exec failed, we fall through to trying to find + * all the needed libraries ourselves by rummaging about + * in the ELF headers... */ + } + } +#endif + + dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr); + if (dynsec) { + dynamic = (Elf32_Dyn*)(byteswap32_to_host(dynsec->sh_offset) + (intptr_t)ehdr); + dynstr = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0); + find_needed_libraries(ehdr, dynamic, dynstr, is_suid); + } + + return 0; +} + + + +int main( int argc, char** argv) +{ + int multi=0; + int got_em_all=1; + char *filename = NULL; + struct library *cur; + + if (argc < 2) { + fprintf(stderr, "ldd: missing file arguments\n"); + fprintf(stderr, "Try `ldd --help' for more information.\n"); + exit(EXIT_FAILURE); + } + if (argc > 2) { + multi++; + } + + while (--argc > 0) { + ++argv; + + if(strcmp(*argv, "--")==0) { + /* Ignore "--" */ + continue; + } + + if(strcmp(*argv, "--help")==0) { + fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"); + fprintf(stderr, "\t--help\t\tprint this help and exit\n"); + exit(EXIT_FAILURE); + } + + filename=*argv; + if (!filename) { + fprintf(stderr, "No filename specified.\n"); + exit(EXIT_FAILURE); + } + + if (multi) { + printf("%s:\n", *argv); + } + + if (find_dependancies(filename)!=0) + continue; + + while(got_em_all) { + got_em_all=0; + /* Keep walking the list till everybody is resolved */ + for (cur = lib_list; cur; cur=cur->next) { + if (cur->resolved == 0 && cur->path) { + got_em_all=1; + //printf("checking sub-depends for '%s\n", cur->path); + find_dependancies(cur->path); + cur->resolved = 1; + } + } + } + + + /* Print the list */ + got_em_all=0; + for (cur = lib_list; cur; cur=cur->next) { + got_em_all=1; + printf("\t%s => %s (0x00000000)\n", cur->name, cur->path); + } + if (interp_dir && got_em_all==1) + printf("\t%s => %s (0x00000000)\n", interp, interp); + if (got_em_all==0) + printf("\tnot a dynamic executable\n"); + + for (cur = lib_list; cur; cur=cur->next) { + free(cur->name); + cur->name=NULL; + free(cur->path); + cur->path=NULL; + } + lib_list=NULL; + } + + return 0; +} + |