/* vi: set sw=4 ts=4: */ /* * A small little ldd implementation for uClibc * * Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.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). * * Licensed under GPLv2 or later */ #include <stdlib.h> #include <stdio.h> #include <fcntl.h> #include <string.h> #include <unistd.h> #include <stdint.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/types.h> #include <sys/wait.h> #include "bswap.h" #include "link.h" #include "dl-defs.h" /* makefile will include elf.h for us */ #ifdef DMALLOC #include <dmalloc.h> #endif #if defined(__alpha__) #define MATCH_MACHINE(x) (x == EM_ALPHA) #define ELFCLASSM ELFCLASS64 #endif #if defined(__arm__) || defined(__thumb__) #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(__hppa__) #define MATCH_MACHINE(x) (x == EM_PARISC) #if defined(__LP64__) #define ELFCLASSM ELFCLASS64 #else #define ELFCLASSM ELFCLASS32 #endif #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(__ia64__) #define MATCH_MACHINE(x) (x == EM_IA_64) #define ELFCLASSM ELFCLASS64 #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(__powerpc64__) #define MATCH_MACHINE(x) (x == EM_PPC64) #define ELFCLASSM ELFCLASS64 #elif 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 #if defined(__cris__) #define MATCH_MACHINE(x) (x == EM_CRIS) #define ELFCLASSM ELFCLASS32 #endif #if defined(__x86_64__) #define MATCH_MACHINE(x) (x == EM_X86_64) #define ELFCLASSM ELFCLASS64 #endif #ifndef MATCH_MACHINE # ifdef __linux__ # include <asm/elf.h> # endif # ifdef ELF_ARCH # define MATCH_MACHINE(x) (x == ELF_ARCH) # endif # ifdef ELF_CLASS # define ELFCLASSM ELF_CLASS # endif #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 #ifndef UCLIBC_RUNTIME_PREFIX # define UCLIBC_RUNTIME_PREFIX "/" #endif struct library { char *name; int resolved; char *path; struct library *next; }; struct library *lib_list = NULL; char not_found[] = "not found"; char *interp_name = 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); } } inline uint64_t byteswap64_to_host(uint64_t value) { if (byteswap == 1) { return (bswap_64(value)); } else { return (value); } } #if ELFCLASSM == ELFCLASS32 # define byteswap_to_host(x) byteswap32_to_host(x) #else # define byteswap_to_host(x) byteswap64_to_host(x) #endif ElfW(Shdr) *elf_find_section_type(uint32_t key, ElfW(Ehdr) *ehdr) { int j; ElfW(Shdr) *shdr; shdr = (ElfW(Shdr) *) (ehdr->e_shoff + (char *)ehdr); for (j = ehdr->e_shnum; --j >= 0; ++shdr) { if (key == byteswap32_to_host(shdr->sh_type)) { return shdr; } } return NULL; } ElfW(Phdr) *elf_find_phdr_type(uint32_t type, ElfW(Ehdr) *ehdr) { int j; ElfW(Phdr) *phdr = (ElfW(Phdr) *) (ehdr->e_phoff + (char *)ehdr); for (j = ehdr->e_phnum; --j >= 0; ++phdr) { if (type == byteswap32_to_host(phdr->p_type)) { return phdr; } } return NULL; } /* Returns value if return_val==1, ptr otherwise */ void *elf_find_dynamic(int64_t const key, ElfW(Dyn) *dynp, ElfW(Ehdr) *ehdr, int return_val) { ElfW(Phdr) *pt_text = elf_find_phdr_type(PT_LOAD, ehdr); unsigned tx_reloc = byteswap_to_host(pt_text->p_vaddr) - byteswap_to_host(pt_text->p_offset); for (; DT_NULL != byteswap_to_host(dynp->d_tag); ++dynp) { if (key == byteswap_to_host(dynp->d_tag)) { if (return_val == 1) return (void *)byteswap_to_host(dynp->d_un.d_val); else return (void *)(byteswap_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr); } } return NULL; } static char *elf_find_rpath(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic) { ElfW(Dyn) *dyns; for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) { if (DT_RPATH == byteswap_to_host(dyns->d_tag)) { char *strtab; strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0); return ((char *)strtab + byteswap_to_host(dyns->d_un.d_val)); } } return NULL; } int check_elf_header(ElfW(Ehdr) *const ehdr) { if (!ehdr || strncmp((char *)ehdr, ELFMAG, SELFMAG) != 0 || ehdr->e_ident[EI_CLASS] != ELFCLASSM || 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 = byteswap_to_host(ehdr->e_phoff); ehdr->e_shoff = byteswap_to_host(ehdr->e_shoff); ehdr->e_phnum = bswap_16(ehdr->e_phnum); ehdr->e_shnum = bswap_16(ehdr->e_shnum); } return 0; } #ifdef __LDSO_CACHE_SUPPORT__ static caddr_t cache_addr = NULL; static size_t cache_size = 0; int map_cache(void) { int fd; struct stat st; header_t *header; libentry_t *libent; int i, strtabsize; if (cache_addr == (caddr_t) - 1) return -1; else if (cache_addr != NULL) return 0; if (stat(LDSO_CACHE, &st) || (fd = open(LDSO_CACHE, O_RDONLY, 0)) < 0) { fprintf(stderr, "ldd: can't open cache '%s'\n", LDSO_CACHE); cache_addr = (caddr_t) - 1; /* so we won't try again */ return -1; } cache_size = st.st_size; cache_addr = mmap(0, cache_size, PROT_READ, MAP_SHARED, fd, 0); close(fd); if (cache_addr == MAP_FAILED) { fprintf(stderr, "ldd: can't map cache '%s'\n", LDSO_CACHE); return -1; } header = (header_t *) cache_addr; if (cache_size < sizeof(header_t) || memcmp(header->magic, LDSO_CACHE_MAGIC, LDSO_CACHE_MAGIC_LEN) || memcmp(header->version, LDSO_CACHE_VER, LDSO_CACHE_VER_LEN) || cache_size < (sizeof(header_t) + header->nlibs * sizeof(libentry_t)) || cache_addr[cache_size - 1] != '\0') { fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE); goto fail; } strtabsize = 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) { fprintf(stderr, "ldd: cache '%s' is corrupt\n", LDSO_CACHE); goto fail; } } return 0; fail: munmap(cache_addr, cache_size); cache_addr = (caddr_t) - 1; return -1; } int unmap_cache(void) { if (cache_addr == NULL || cache_addr == (caddr_t) - 1) return -1; #if 1 munmap(cache_addr, cache_size); cache_addr = NULL; #endif return 0; } #else static inline void map_cache(void) { } static inline void unmap_cache(void) { } #endif /* This function's behavior must exactly match that * in uClibc/ldso/ldso/dl-elf.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(ElfW(Ehdr) *ehdr, ElfW(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 = strdup(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 = elf_find_rpath(ehdr, dynamic); 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 __LDSO_CACHE_SUPPORT__ if (cache_addr != NULL && cache_addr != (caddr_t) - 1) { int i; header_t *header = (header_t *) cache_addr; libentry_t *libent = (libentry_t *) & header[1]; char *strs = (char *)&libent[header->nlibs]; 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) && strcmp(lib->name, strs + libent[i].sooffset) == 0) { lib->path = strdup(strs + libent[i].liboffset); return; } } } #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/dl-elf.c */ path = UCLIBC_RUNTIME_PREFIX "lib:" UCLIBC_RUNTIME_PREFIX "usr/lib" #ifndef __LDSO_CACHE_SUPPORT__ ":" UCLIBC_RUNTIME_PREFIX "usr/X11R6/lib" #endif ; 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(ElfW(Ehdr) *ehdr, ElfW(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 ldso elsewhere */ if (interpreter_already_found && (tmp = strrchr(interp_name, '/')) != NULL) { int len = strlen(interp_dir); if (strcmp(s, interp_name + 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(ElfW(Ehdr) *ehdr, ElfW(Dyn) *dynamic, int is_setuid) { ElfW(Dyn) *dyns; for (dyns = dynamic; byteswap_to_host(dyns->d_tag) != DT_NULL; ++dyns) { if (DT_NEEDED == byteswap_to_host(dyns->d_tag)) { char *strtab; strtab = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0); add_library(ehdr, dynamic, is_setuid, (char *)strtab + byteswap_to_host(dyns->d_un.d_val)); } } } static struct library *find_elf_interpreter(ElfW(Ehdr) *ehdr) { ElfW(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 + byteswap_to_host(phdr->p_offset); char *tmp, *tmp1; interp_name = strdup(s); interp_dir = strdup(s); tmp = strrchr(interp_dir, '/'); if (*tmp) *tmp = '\0'; else { free(interp_dir); interp_dir = interp_name; } 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); if (newlib->path != not_found) { free(newlib->path); } newlib->name = NULL; newlib->path = NULL; 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 = strdup(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 */ /* #warning "There may be two warnings here about vfork() clobbering, ignore them" */ int find_dependancies(char *filename) { int is_suid = 0; FILE *thefile; struct library *interp; struct stat statbuf; ElfW(Ehdr) *ehdr = NULL; ElfW(Shdr) *dynsec = NULL; ElfW(Dyn) *dynamic = NULL; 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); fclose(thefile); return -1; } if ((size_t) statbuf.st_size < sizeof(ElfW(Ehdr))) goto foo; if (!S_ISREG(statbuf.st_mode)) goto foo; /* mmap the file to make reading stuff from it effortless */ ehdr = mmap(0, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0); if (ehdr == MAP_FAILED) { fclose(thefile); fprintf(stderr, "Out of memory!\n"); return -1; } foo: fclose(thefile); /* 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 || ehdr->e_type == ET_DYN) { 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_type == ET_DYN) && 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 = vfork()) == 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 = (ElfW(Dyn) *) (byteswap_to_host(dynsec->sh_offset) + (char *)ehdr); find_needed_libraries(ehdr, dynamic, 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 || strcmp(*argv, "-h") == 0) { fprintf(stderr, "Usage: ldd [OPTION]... FILE...\n"); fprintf(stderr, "\t--help\t\tprint this help and exit\n"); exit(EXIT_SUCCESS); } filename = *argv; if (!filename) { fprintf(stderr, "No filename specified.\n"); exit(EXIT_FAILURE); } if (multi) { printf("%s:\n", *argv); } map_cache(); 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; } } } unmap_cache(); /* 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_name && interpreter_already_found == 1) printf("\t%s => %s (0x00000000)\n", interp_name, interp_name); else printf("\tnot a dynamic executable\n"); for (cur = lib_list; cur; cur = cur->next) { free(cur->name); cur->name = NULL; if (cur->path && cur->path != not_found) { free(cur->path); cur->path = NULL; } } lib_list = NULL; } return 0; }