diff options
Diffstat (limited to 'elf.c')
| -rw-r--r-- | elf.c | 619 |
1 files changed, 0 insertions, 619 deletions
@@ -1,619 +0,0 @@ -# include "config.h" - -#include <endian.h> -#include <errno.h> -#include <error.h> -#include <fcntl.h> -#include <gelf.h> -#include <stdint.h> -#include <stdlib.h> -#include <string.h> -#include <unistd.h> - -#include "common.h" - -static void do_init_elf(struct ltelf *lte, const char *filename); -static void do_close_elf(struct ltelf *lte); -static void add_library_symbol(GElf_Addr addr, const char *name, - struct library_symbol **library_symbolspp, - enum toplt type_of_plt, int is_weak); -static int in_load_libraries(const char *name, struct ltelf *lte); -static GElf_Addr opd2addr(struct ltelf *ltc, GElf_Addr addr); - -#ifdef PLT_REINITALISATION_BP -extern char *PLTs_initialized_by_here; -#endif - -static void -do_init_elf(struct ltelf *lte, const char *filename) { - int i; - GElf_Addr relplt_addr = 0; - size_t relplt_size = 0; - - debug(DEBUG_FUNCTION, "do_init_elf(filename=%s)", filename); - debug(1, "Reading ELF from %s...", filename); - - memset(lte, 0, sizeof(*lte)); - lte->fd = open(filename, O_RDONLY); - if (lte->fd == -1) - error(EXIT_FAILURE, errno, "Can't open \"%s\"", filename); - -#ifdef HAVE_ELF_C_READ_MMAP - lte->elf = elf_begin(lte->fd, ELF_C_READ_MMAP, NULL); -#else - lte->elf = elf_begin(lte->fd, ELF_C_READ, NULL); -#endif - - if (lte->elf == NULL || elf_kind(lte->elf) != ELF_K_ELF) - error(EXIT_FAILURE, 0, "Can't open ELF file \"%s\"", filename); - - if (gelf_getehdr(lte->elf, <e->ehdr) == NULL) - error(EXIT_FAILURE, 0, "Can't read ELF header of \"%s\"", - filename); - - if (lte->ehdr.e_type != ET_EXEC && lte->ehdr.e_type != ET_DYN) - error(EXIT_FAILURE, 0, - "\"%s\" is not an ELF executable nor shared library", - filename); - - if ((lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS - || lte->ehdr.e_machine != LT_ELF_MACHINE) -#ifdef LT_ELF_MACHINE2 - && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS2 - || lte->ehdr.e_machine != LT_ELF_MACHINE2) -#endif -#ifdef LT_ELF_MACHINE3 - && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS3 - || lte->ehdr.e_machine != LT_ELF_MACHINE3) -#endif - ) - error(EXIT_FAILURE, 0, - "\"%s\" is ELF from incompatible architecture", filename); - - for (i = 1; i < lte->ehdr.e_shnum; ++i) { - Elf_Scn *scn; - GElf_Shdr shdr; - const char *name; - - scn = elf_getscn(lte->elf, i); - if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get section header from \"%s\"", - filename); - - name = elf_strptr(lte->elf, lte->ehdr.e_shstrndx, shdr.sh_name); - if (name == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get section header from \"%s\"", - filename); - - if (shdr.sh_type == SHT_SYMTAB) { - Elf_Data *data; - - lte->symtab = elf_getdata(scn, NULL); - lte->symtab_count = shdr.sh_size / shdr.sh_entsize; - if ((lte->symtab == NULL - || elf_getdata(scn, lte->symtab) != NULL) - && opt_x != NULL) - error(EXIT_FAILURE, 0, - "Couldn't get .symtab data from \"%s\"", - filename); - - scn = elf_getscn(lte->elf, shdr.sh_link); - if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get section header from \"%s\"", - filename); - - data = elf_getdata(scn, NULL); - if (data == NULL || elf_getdata(scn, data) != NULL - || shdr.sh_size != data->d_size || data->d_off) - error(EXIT_FAILURE, 0, - "Couldn't get .strtab data from \"%s\"", - filename); - - lte->strtab = data->d_buf; - } else if (shdr.sh_type == SHT_DYNSYM) { - Elf_Data *data; - - lte->dynsym = elf_getdata(scn, NULL); - lte->dynsym_count = shdr.sh_size / shdr.sh_entsize; - if (lte->dynsym == NULL - || elf_getdata(scn, lte->dynsym) != NULL) - error(EXIT_FAILURE, 0, - "Couldn't get .dynsym data from \"%s\"", - filename); - - scn = elf_getscn(lte->elf, shdr.sh_link); - if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get section header from \"%s\"", - filename); - - data = elf_getdata(scn, NULL); - if (data == NULL || elf_getdata(scn, data) != NULL - || shdr.sh_size != data->d_size || data->d_off) - error(EXIT_FAILURE, 0, - "Couldn't get .dynstr data from \"%s\"", - filename); - - lte->dynstr = data->d_buf; - } else if (shdr.sh_type == SHT_DYNAMIC) { - Elf_Data *data; - size_t j; - - data = elf_getdata(scn, NULL); - if (data == NULL || elf_getdata(scn, data) != NULL) - error(EXIT_FAILURE, 0, - "Couldn't get .dynamic data from \"%s\"", - filename); - - for (j = 0; j < shdr.sh_size / shdr.sh_entsize; ++j) { - GElf_Dyn dyn; - - if (gelf_getdyn(data, j, &dyn) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get .dynamic data from \"%s\"", - filename); -#ifdef __mips__ -/** - MIPS ABI Supplement: - - DT_PLTGOT This member holds the address of the .got section. - - DT_MIPS_SYMTABNO This member holds the number of entries in the - .dynsym section. - - DT_MIPS_LOCAL_GOTNO This member holds the number of local global - offset table entries. - - DT_MIPS_GOTSYM This member holds the index of the first dyamic - symbol table entry that corresponds to an entry in the gobal offset - table. - - */ - if(dyn.d_tag==DT_PLTGOT){ - lte->pltgot_addr=dyn.d_un.d_ptr; - } - if(dyn.d_tag==DT_MIPS_LOCAL_GOTNO){ - lte->mips_local_gotno=dyn.d_un.d_val; - } - if(dyn.d_tag==DT_MIPS_GOTSYM){ - lte->mips_gotsym=dyn.d_un.d_val; - } -#endif // __mips__ - if (dyn.d_tag == DT_JMPREL) - relplt_addr = dyn.d_un.d_ptr; - else if (dyn.d_tag == DT_PLTRELSZ) - relplt_size = dyn.d_un.d_val; - } - } else if (shdr.sh_type == SHT_HASH) { - Elf_Data *data; - size_t j; - - lte->hash_type = SHT_HASH; - - data = elf_getdata(scn, NULL); - if (data == NULL || elf_getdata(scn, data) != NULL - || data->d_off || data->d_size != shdr.sh_size) - error(EXIT_FAILURE, 0, - "Couldn't get .hash data from \"%s\"", - filename); - - if (shdr.sh_entsize == 4) { - /* Standard conforming ELF. */ - if (data->d_type != ELF_T_WORD) - error(EXIT_FAILURE, 0, - "Couldn't get .hash data from \"%s\"", - filename); - lte->hash = (Elf32_Word *) data->d_buf; - } else if (shdr.sh_entsize == 8) { - /* Alpha or s390x. */ - Elf32_Word *dst, *src; - size_t hash_count = data->d_size / 8; - - lte->hash = (Elf32_Word *) - malloc(hash_count * sizeof(Elf32_Word)); - if (lte->hash == NULL) - error(EXIT_FAILURE, 0, - "Couldn't convert .hash section from \"%s\"", - filename); - lte->lte_flags |= LTE_HASH_MALLOCED; - dst = lte->hash; - src = (Elf32_Word *) data->d_buf; - if ((data->d_type == ELF_T_WORD - && __BYTE_ORDER == __BIG_ENDIAN) - || (data->d_type == ELF_T_XWORD - && lte->ehdr.e_ident[EI_DATA] == - ELFDATA2MSB)) - ++src; - for (j = 0; j < hash_count; ++j, src += 2) - *dst++ = *src; - } else - error(EXIT_FAILURE, 0, - "Unknown .hash sh_entsize in \"%s\"", - filename); - } else if (shdr.sh_type == SHT_GNU_HASH - && lte->hash == NULL) { - Elf_Data *data; - - lte->hash_type = SHT_GNU_HASH; - - if (shdr.sh_entsize != 0 - && shdr.sh_entsize != 4) { - error(EXIT_FAILURE, 0, - ".gnu.hash sh_entsize in \"%s\" should be 4, but is %llu", - filename, shdr.sh_entsize); - } - - data = elf_getdata(scn, NULL); - if (data == NULL || elf_getdata(scn, data) != NULL - || data->d_off || data->d_size != shdr.sh_size) - error(EXIT_FAILURE, 0, - "Couldn't get .gnu.hash data from \"%s\"", - filename); - - lte->hash = (Elf32_Word *) data->d_buf; - } else if (shdr.sh_type == SHT_PROGBITS - || shdr.sh_type == SHT_NOBITS) { - if (strcmp(name, ".plt") == 0) { - lte->plt_addr = shdr.sh_addr; - lte->plt_size = shdr.sh_size; - if (shdr.sh_flags & SHF_EXECINSTR) { - lte->lte_flags |= LTE_PLT_EXECUTABLE; - } - } -#ifdef ARCH_SUPPORTS_OPD - else if (strcmp(name, ".opd") == 0) { - lte->opd_addr = (GElf_Addr *) (long) shdr.sh_addr; - lte->opd_size = shdr.sh_size; - lte->opd = elf_rawdata(scn, NULL); - } -#endif - } - } - - if (lte->dynsym == NULL || lte->dynstr == NULL) - error(EXIT_FAILURE, 0, - "Couldn't find .dynsym or .dynstr in \"%s\"", filename); - - if (!relplt_addr || !lte->plt_addr) { - debug(1, "%s has no PLT relocations", filename); - lte->relplt = NULL; - lte->relplt_count = 0; - } else { - for (i = 1; i < lte->ehdr.e_shnum; ++i) { - Elf_Scn *scn; - GElf_Shdr shdr; - - scn = elf_getscn(lte->elf, i); - if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get section header from \"%s\"", - filename); - if (shdr.sh_addr == relplt_addr - && shdr.sh_size == relplt_size) { - lte->relplt = elf_getdata(scn, NULL); - lte->relplt_count = - shdr.sh_size / shdr.sh_entsize; - if (lte->relplt == NULL - || elf_getdata(scn, lte->relplt) != NULL) - error(EXIT_FAILURE, 0, - "Couldn't get .rel*.plt data from \"%s\"", - filename); - break; - } - } - - if (i == lte->ehdr.e_shnum) - error(EXIT_FAILURE, 0, - "Couldn't find .rel*.plt section in \"%s\"", - filename); - - debug(1, "%s %zd PLT relocations", filename, lte->relplt_count); - } -} - -static void -do_close_elf(struct ltelf *lte) { - debug(DEBUG_FUNCTION, "do_close_elf()"); - if (lte->lte_flags & LTE_HASH_MALLOCED) - free((char *)lte->hash); - elf_end(lte->elf); - close(lte->fd); -} - -static void -add_library_symbol(GElf_Addr addr, const char *name, - struct library_symbol **library_symbolspp, - enum toplt type_of_plt, int is_weak) { - struct library_symbol *s; - - debug(DEBUG_FUNCTION, "add_library_symbol()"); - - s = malloc(sizeof(struct library_symbol) + strlen(name) + 1); - if (s == NULL) - error(EXIT_FAILURE, errno, "add_library_symbol failed"); - - s->needs_init = 1; - s->is_weak = is_weak; - s->plt_type = type_of_plt; - s->next = *library_symbolspp; - s->enter_addr = (void *)(uintptr_t) addr; - s->name = (char *)(s + 1); - strcpy(s->name, name); - *library_symbolspp = s; - - debug(2, "addr: %p, symbol: \"%s\"", (void *)(uintptr_t) addr, name); -} - -/* stolen from elfutils-0.123 */ -static unsigned long -private_elf_gnu_hash(const char *name) { - unsigned long h = 5381; - const unsigned char *string = (const unsigned char *)name; - unsigned char c; - for (c = *string; c; c = *++string) - h = h * 33 + c; - return h & 0xffffffff; -} - -static int -in_load_libraries(const char *name, struct ltelf *lte) { - size_t i; - unsigned long hash; - unsigned long gnu_hash; - - if (!library_num) - return 1; - - hash = elf_hash((const unsigned char *)name); - gnu_hash = private_elf_gnu_hash(name); - for (i = 1; i <= library_num; ++i) { - if (lte[i].hash == NULL) - continue; - - if (lte[i].hash_type == SHT_GNU_HASH) { - Elf32_Word * hashbase = lte[i].hash; - Elf32_Word nbuckets = *hashbase++; - Elf32_Word symbias = *hashbase++; - Elf32_Word bitmask_nwords = *hashbase++; - Elf32_Word * buckets; - Elf32_Word * chain_zero; - Elf32_Word bucket; - - // +1 for skipped `shift' - hashbase += lte[i].ehdr.e_ident[EI_CLASS] * bitmask_nwords + 1; - buckets = hashbase; - hashbase += nbuckets; - chain_zero = hashbase - symbias; - bucket = buckets[gnu_hash % nbuckets]; - - if (bucket != 0) { - const Elf32_Word *hasharr = &chain_zero[bucket]; - do - if ((*hasharr & ~1u) == (gnu_hash & ~1u)) { - int symidx = hasharr - chain_zero; - GElf_Sym sym; - - if (gelf_getsym(lte[i].dynsym, symidx, &sym) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get symbol from .dynsym"); - - if (sym.st_value != 0 - && sym.st_shndx != SHN_UNDEF - && strcmp(name, lte[i].dynstr + sym.st_name) == 0) - return 1; - } - while ((*hasharr++ & 1u) == 0); - } - } else { - Elf32_Word nbuckets, symndx; - Elf32_Word *buckets, *chain; - nbuckets = lte[i].hash[0]; - buckets = <e[i].hash[2]; - chain = <e[i].hash[2 + nbuckets]; - - for (symndx = buckets[hash % nbuckets]; - symndx != STN_UNDEF; symndx = chain[symndx]) { - GElf_Sym sym; - - if (gelf_getsym(lte[i].dynsym, symndx, &sym) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get symbol from .dynsym"); - - if (sym.st_value != 0 - && sym.st_shndx != SHN_UNDEF - && strcmp(name, lte[i].dynstr + sym.st_name) == 0) - return 1; - } - } - } - return 0; -} - -static GElf_Addr -opd2addr(struct ltelf *lte, GElf_Addr addr) { -#ifdef ARCH_SUPPORTS_OPD - unsigned long base, offset; - - if (!lte->opd) - return addr; - - base = (unsigned long)lte->opd->d_buf; - offset = (unsigned long)addr - (unsigned long)lte->opd_addr; - if (offset > lte->opd_size) - error(EXIT_FAILURE, 0, "static plt not in .opd"); - - return *(GElf_Addr*)(base + offset); -#else //!ARCH_SUPPORTS_OPD - return addr; -#endif -} - -struct library_symbol * -read_elf(Process *proc) { - struct library_symbol *library_symbols = NULL; - struct ltelf lte[MAX_LIBRARIES + 1]; - size_t i; - struct opt_x_t *xptr; - struct library_symbol **lib_tail = NULL; - int exit_out = 0; - - debug(DEBUG_FUNCTION, "read_elf(file=%s)", proc->filename); - - elf_version(EV_CURRENT); - - do_init_elf(lte, proc->filename); - proc->e_machine = lte->ehdr.e_machine; - for (i = 0; i < library_num; ++i) - do_init_elf(<e[i + 1], library[i]); -#ifdef __mips__ - // MIPS doesn't use the PLT and the GOT entries get changed - // on startup. - proc->need_to_reinitialize_breakpoints = 1; - for(i=lte->mips_gotsym; i<lte->dynsym_count;i++){ - GElf_Sym sym; - const char *name; - GElf_Addr addr = arch_plt_sym_val(lte, i, 0); - if (gelf_getsym(lte->dynsym, i, &sym) == NULL){ - error(EXIT_FAILURE, 0, - "Couldn't get relocation from \"%s\"", - proc->filename); - } - name=lte->dynstr+sym.st_name; - if(ELF64_ST_TYPE(sym.st_info) != STT_FUNC){ - debug(2,"sym %s not a function",name); - continue; - } - add_library_symbol(addr, name, &library_symbols, 0, - ELF64_ST_BIND(sym.st_info) != 0); - if (!lib_tail) - lib_tail = &(library_symbols->next); - } -#else - for (i = 0; i < lte->relplt_count; ++i) { - GElf_Rel rel; - GElf_Rela rela; - GElf_Sym sym; - GElf_Addr addr; - void *ret; - const char *name; - - if (lte->relplt->d_type == ELF_T_REL) { - ret = gelf_getrel(lte->relplt, i, &rel); - rela.r_offset = rel.r_offset; - rela.r_info = rel.r_info; - rela.r_addend = 0; - } else - ret = gelf_getrela(lte->relplt, i, &rela); - - if (ret == NULL - || ELF64_R_SYM(rela.r_info) >= lte->dynsym_count - || gelf_getsym(lte->dynsym, ELF64_R_SYM(rela.r_info), - &sym) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get relocation from \"%s\"", - proc->filename); - -#ifdef PLT_REINITALISATION_BP - if (!sym.st_value && PLTs_initialized_by_here) - proc->need_to_reinitialize_breakpoints = 1; -#endif - - name = lte->dynstr + sym.st_name; - if (in_load_libraries(name, lte)) { - addr = arch_plt_sym_val(lte, i, &rela); - add_library_symbol(addr, name, &library_symbols, - (PLTS_ARE_EXECUTABLE(lte) - ? LS_TOPLT_EXEC : LS_TOPLT_POINT), - ELF64_ST_BIND(sym.st_info) == STB_WEAK); - if (!lib_tail) - lib_tail = &(library_symbols->next); - } - } -#endif // !__mips__ -#ifdef PLT_REINITALISATION_BP - struct opt_x_t *main_cheat; - - if (proc->need_to_reinitialize_breakpoints) { - /* Add "PLTs_initialized_by_here" to opt_x list, if not - already there. */ - main_cheat = (struct opt_x_t *)malloc(sizeof(struct opt_x_t)); - if (main_cheat == NULL) - error(EXIT_FAILURE, 0, "Couldn't allocate memory"); - main_cheat->next = opt_x; - main_cheat->found = 0; - main_cheat->name = PLTs_initialized_by_here; - - for (xptr = opt_x; xptr; xptr = xptr->next) - if (strcmp(xptr->name, PLTs_initialized_by_here) == 0 - && main_cheat) { - free(main_cheat); - main_cheat = NULL; - break; - } - if (main_cheat) - opt_x = main_cheat; - } -#endif - - for (i = 0; i < lte->symtab_count; ++i) { - GElf_Sym sym; - GElf_Addr addr; - const char *name; - - if (gelf_getsym(lte->symtab, i, &sym) == NULL) - error(EXIT_FAILURE, 0, - "Couldn't get symbol from \"%s\"", - proc->filename); - - name = lte->strtab + sym.st_name; - addr = sym.st_value; - if (!addr) - continue; - - for (xptr = opt_x; xptr; xptr = xptr->next) - if (xptr->name && strcmp(xptr->name, name) == 0) { - /* FIXME: Should be able to use &library_symbols as above. But - when you do, none of the real library symbols cause breaks. */ - add_library_symbol(opd2addr(lte, addr), - name, lib_tail, LS_TOPLT_NONE, 0); - xptr->found = 1; - break; - } - } - for (xptr = opt_x; xptr; xptr = xptr->next) - if ( ! xptr->found) { - char *badthing = "WARNING"; -#ifdef PLT_REINITALISATION_BP - if (strcmp(xptr->name, PLTs_initialized_by_here) == 0) { - if (lte->ehdr.e_entry) { - add_library_symbol ( - opd2addr (lte, lte->ehdr.e_entry), - PLTs_initialized_by_here, - lib_tail, 1, 0); - fprintf (stderr, "WARNING: Using e_ent" - "ry from elf header (%p) for " - "address of \"%s\"\n", (void*) - (long) lte->ehdr.e_entry, - PLTs_initialized_by_here); - continue; - } - badthing = "ERROR"; - exit_out = 1; - } -#endif - fprintf (stderr, - "%s: Couldn't find symbol \"%s\" in file \"%s" - "\"\n", badthing, xptr->name, proc->filename); - } - if (exit_out) { - exit (1); - } - - for (i = 0; i < library_num + 1; ++i) - do_close_elf(<e[i]); - - return library_symbols; -} |