/* $OpenBSD: rtld_machine.c,v 1.13 2003/09/04 19:37:07 drahn Exp $ */ /* * Copyright (c) 2002 Dale Rahn * Copyright (c) 2001 Niklas Hallqvist * Copyright (c) 2001 Artur Grabowski * * 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. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. */ /*- * Copyright (c) 2000 Eduardo Horvath. * Copyright (c) 1999 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Paul Kranenburg. * * 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. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND 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 FOUNDATION OR 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. */ #define _DYN_LOADER #include #include #include #include #include #include #include "syscall.h" #include "archdep.h" #include "resolve.h" void _dl_bcopy(const void *src, void *dest, int size) { const unsigned char *psrc = src; unsigned char *pdest = dest; int i; for (i = 0; i < size; i++) pdest[i] = psrc[i]; } /* * The following table holds for each relocation type: * - the width in bits of the memory location the relocation * applies to (not currently used) * - the number of bits the relocation value must be shifted to the * right (i.e. discard least significant bits) to fit into * the appropriate field in the instruction word. * - flags indicating whether * * the relocation involves a symbol * * the relocation is relative to the current position * * the relocation is for a GOT entry * * the relocation is relative to the load address * */ #define _RF_S 0x80000000 /* Resolve symbol */ #define _RF_A 0x40000000 /* Use addend */ #define _RF_P 0x20000000 /* Location relative */ #define _RF_G 0x10000000 /* GOT offset */ #define _RF_B 0x08000000 /* Load address relative */ #define _RF_U 0x04000000 /* Unaligned */ #define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ #define _RF_RS(s) ((s) & 0xff) /* right shift */ static int reloc_target_flags[] = { 0, /* NONE */ _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32*/ _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC32 */ _RF_G| _RF_SZ(32) | _RF_RS(00), /* GOT32 */ _RF_A| _RF_SZ(32) | _RF_RS(0), /* PLT32 */ _RF_S| _RF_SZ(32) | _RF_RS(0), /* COPY */ _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */ _RF_S| _RF_SZ(32) | _RF_RS(0), /* JUMP_SLOT */ _RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */ 0, /* GOTOFF XXX */ 0, /* GOTPC XXX */ 0, /* DUMMY 11 */ 0, /* DUMMY 12 */ 0, /* DUMMY 13 */ 0, /* DUMMY 14 */ 0, /* DUMMY 15 */ 0, /* DUMMY 16 */ 0, /* DUMMY 17 */ 0, /* DUMMY 18 */ 0, /* DUMMY 19 */ _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* PC_16 */ _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* RELOC_PC8 */ }; #define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) #define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) #define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) #define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0) #define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0) #define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) #define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) static long reloc_target_bitmask[] = { #define _BM(x) (~(-(1ULL << (x)))) 0, /* NONE */ _BM(32), /* RELOC_32*/ _BM(32), /* PC32 */ _BM(32), /* GOT32 */ _BM(32), /* PLT32 */ 0, /* COPY */ _BM(32), /* GLOB_DAT */ _BM(32), /* JUMP_SLOT */ _BM(32), /* RELATIVE */ 0, /* GOTOFF XXX */ 0, /* GOTPC XXX */ 0, /* DUMMY 11 */ 0, /* DUMMY 12 */ 0, /* DUMMY 13 */ 0, /* DUMMY 14 */ 0, /* DUMMY 15 */ 0, /* DUMMY 16 */ 0, /* DUMMY 17 */ 0, /* DUMMY 18 */ 0, /* DUMMY 19 */ _BM(16), /* RELOC_16 */ _BM(8), /* PC_16 */ _BM(8), /* RELOC_8 */ _BM(8), /* RELOC_PC8 */ #undef _BM }; #define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) void _dl_reloc_plt(Elf_Addr *where, Elf_Addr value); int _dl_md_reloc(elf_object_t *object, int rel, int relsz) { long i; long numrel; long fails = 0; Elf_Addr loff; Elf_Rel *rels; struct load_list *llist; loff = object->load_offs; numrel = object->Dyn.info[relsz] / sizeof(Elf32_Rel); rels = (Elf32_Rel *)(object->Dyn.info[rel]); if (rels == NULL) return(0); /* * unprotect some segments if we need it. */ if ((rel == DT_REL || rel == DT_RELA)) { for (llist = object->load_list; llist != NULL; llist = llist->next) { if (!(llist->prot & PROT_WRITE)) _dl_mprotect(llist->start, llist->size, llist->prot|PROT_WRITE); } } for (i = 0; i < numrel; i++, rels++) { Elf_Addr *where, value, ooff, mask; Elf_Word type; const Elf_Sym *sym, *this; const char *symn; type = ELF_R_TYPE(rels->r_info); if (type == R_TYPE(NONE)) continue; if (type == R_TYPE(JUMP_SLOT) && rel != DT_JMPREL) continue; where = (Elf_Addr *)(rels->r_offset + loff); if (RELOC_USE_ADDEND(type)) value = *where & RELOC_VALUE_BITMASK(type); else value = 0; sym = NULL; symn = NULL; if (RELOC_RESOLVE_SYMBOL(type)) { sym = object->dyn.symtab; sym += ELF_R_SYM(rels->r_info); symn = object->dyn.strtab + sym->st_name; if (sym->st_shndx != SHN_UNDEF && ELF_ST_BIND(sym->st_info) == STB_LOCAL) { value += loff; } else { this = NULL; ooff = _dl_find_symbol_bysym(object, ELF_R_SYM(rels->r_info), _dl_objects, &this, SYM_SEARCH_ALL|SYM_WARNNOTFOUND| ((type == R_TYPE(JUMP_SLOT))? SYM_PLT:SYM_NOTPLT), sym->st_size); if (this == NULL) { resolve_failed: _dl_printf("%s: %s: can't resolve " "reference '%s'\n", _dl_progname, object->load_name, symn); fails++; continue; } value += (Elf_Addr)(ooff + this->st_value); } } if (type == R_TYPE(JUMP_SLOT)) { _dl_reloc_plt((Elf_Word *)where, value); continue; } if (type == R_TYPE(COPY)) { void *dstaddr = where; const void *srcaddr; const Elf_Sym *dstsym = sym, *srcsym = NULL; size_t size = dstsym->st_size; Elf_Addr soff; soff = _dl_find_symbol(symn, object->next, &srcsym, SYM_SEARCH_ALL|SYM_WARNNOTFOUND| ((type == R_TYPE(JUMP_SLOT)) ? SYM_PLT:SYM_NOTPLT), size, object); if (srcsym == NULL) goto resolve_failed; srcaddr = (void *)(soff + srcsym->st_value); _dl_bcopy(srcaddr, dstaddr, size); continue; } if (RELOC_PC_RELATIVE(type)) value -= (Elf_Addr)where; if (RELOC_BASE_RELATIVE(type)) value += loff; mask = RELOC_VALUE_BITMASK(type); value >>= RELOC_VALUE_RIGHTSHIFT(type); value &= mask; if (RELOC_UNALIGNED(type)) { /* Handle unaligned relocations. */ Elf_Addr tmp = 0; char *ptr = (char *)where; int i, size = RELOC_TARGET_SIZE(type)/8; /* Read it in one byte at a time. */ for (i=0; i> (8*i)) & 0xff); } else if (RELOC_TARGET_SIZE(type) > 32) { *where &= ~mask; *where |= value; } else { Elf32_Addr *where32 = (Elf32_Addr *)where; *where32 &= ~mask; *where32 |= value; } } /* reprotect the unprotected segments */ if ((rel == DT_REL || rel == DT_RELA)) { for (llist = object->load_list; llist != NULL; llist = llist->next) { if (!(llist->prot & PROT_WRITE)) _dl_mprotect(llist->start, llist->size, llist->prot); } } return (fails); } #if 0 struct jmpslot { u_short opcode; u_short addr[2]; u_short reloc_index; #define JMPSLOT_RELOC_MASK 0xffff }; #define JUMP 0xe990 /* NOP + JMP opcode */ #endif void _dl_reloc_plt(Elf_Addr *where, Elf_Addr value) { *where = value; } /* * Resolve a symbol at run-time. */ Elf_Addr _dl_bind(elf_object_t *object, int index) { Elf_Rel *rel; Elf_Word *addr; const Elf_Sym *sym, *this; const char *symn; Elf_Addr ooff; sigset_t omask, nmask; rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]); rel += index/sizeof(Elf_Rel); sym = object->dyn.symtab; sym += ELF_R_SYM(rel->r_info); symn = object->dyn.strtab + sym->st_name; addr = (Elf_Word *)(object->load_offs + rel->r_offset); this = NULL; ooff = _dl_find_symbol(symn, _dl_objects, &this, SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_PLT, sym->st_size, object); if (this == NULL) { _dl_printf("lazy binding failed!\n"); *((int *)0) = 0; /* XXX */ } /* if GOT is protected, allow the write */ if (object->got_size != 0) { sigfillset(&nmask); _dl_sigprocmask(SIG_BLOCK, &nmask, &omask); _dl_mprotect((void*)object->got_start, object->got_size, PROT_READ|PROT_WRITE); } _dl_reloc_plt(addr, ooff + this->st_value); /* put the GOT back to RO */ if (object->got_size != 0) { _dl_mprotect((void*)object->got_start, object->got_size, PROT_READ); _dl_sigprocmask(SIG_SETMASK, &omask, NULL); } return((Elf_Addr)ooff + this->st_value); } void _dl_md_reloc_got(elf_object_t *object, int lazy) { extern void _dl_bind_start(void); /* XXX */ Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT]; int i, num; Elf_Rel *rel; struct load_list *llist; Elf_Addr ooff; const Elf_Sym *this; if (pltgot == NULL) return; /* it is possible to have no PLT/GOT relocations */ pltgot[1] = (Elf_Addr)object; pltgot[2] = (Elf_Addr)&_dl_bind_start; if (object->Dyn.info[DT_PLTREL] != DT_REL) return; object->got_addr = NULL; object->got_size = 0; this = NULL; ooff = _dl_find_symbol("__got_start", object, &this, SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, 0, object); if (this != NULL) object->got_addr = ooff + this->st_value; this = NULL; ooff = _dl_find_symbol("__got_end", object, &this, SYM_SEARCH_SELF|SYM_NOWARNNOTFOUND|SYM_PLT, 0, object); if (this != NULL) object->got_size = ooff + this->st_value - object->got_addr; if (object->got_addr == NULL) object->got_start = NULL; else { object->got_start = ELF_TRUNC(object->got_addr, _dl_pagesz); object->got_size += object->got_addr - object->got_start; object->got_size = ELF_ROUND(object->got_size, _dl_pagesz); } if (!lazy) { _dl_md_reloc(object, DT_JMPREL, DT_PLTRELSZ); } else { rel = (Elf_Rel *)(object->Dyn.info[DT_JMPREL]); num = (object->Dyn.info[DT_PLTRELSZ]); for (llist = object->load_list; llist != NULL; llist = llist->next) { if (!(llist->prot & PROT_WRITE)) _dl_mprotect(llist->start, llist->size, llist->prot|PROT_WRITE); } for (i = 0; i < num/sizeof(Elf_Rel); i++, rel++) { Elf_Addr *where; where = (Elf_Addr *)(rel->r_offset + object->load_offs); *where += object->load_offs; } for (llist = object->load_list; llist != NULL; llist = llist->next) { if (!(llist->prot & PROT_WRITE)) _dl_mprotect(llist->start, llist->size, llist->prot); } } /* PLT is already RO on i386, no point in mprotecting it, just GOT */ if (object->got_size != 0) _dl_mprotect((void*)object->got_start, object->got_size, PROT_READ); }