134192Sjdp/*- 234192Sjdp * Copyright 1996-1998 John D. Polstra. 334192Sjdp * All rights reserved. 434192Sjdp * 534192Sjdp * Redistribution and use in source and binary forms, with or without 634192Sjdp * modification, are permitted provided that the following conditions 734192Sjdp * are met: 834192Sjdp * 1. Redistributions of source code must retain the above copyright 934192Sjdp * notice, this list of conditions and the following disclaimer. 1034192Sjdp * 2. Redistributions in binary form must reproduce the above copyright 1134192Sjdp * notice, this list of conditions and the following disclaimer in the 1234192Sjdp * documentation and/or other materials provided with the distribution. 1334192Sjdp * 1434192Sjdp * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 1534192Sjdp * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 1634192Sjdp * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 1734192Sjdp * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 1834192Sjdp * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 1934192Sjdp * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2034192Sjdp * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2134192Sjdp * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 2234192Sjdp * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 2334192Sjdp * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 2434192Sjdp * 2550476Speter * $FreeBSD$ 2634192Sjdp */ 2734192Sjdp 2834192Sjdp#include <sys/param.h> 2934192Sjdp#include <sys/mman.h> 3050609Sjdp#include <sys/stat.h> 3134192Sjdp 3234192Sjdp#include <errno.h> 3334192Sjdp#include <stddef.h> 3450608Sjdp#include <stdlib.h> 3534192Sjdp#include <string.h> 3634192Sjdp#include <unistd.h> 3734192Sjdp 3885004Sdfr#include "debug.h" 3934192Sjdp#include "rtld.h" 4034192Sjdp 41237058Skibstatic Elf_Ehdr *get_elf_header(int, const char *); 42107948Sdillonstatic int convert_flags(int); /* Elf flags -> mmap flags */ 4334192Sjdp 4434192Sjdp/* 4548871Sjdp * Map a shared object into memory. The "fd" argument is a file descriptor, 4634192Sjdp * which must be open on the object and positioned at its beginning. 4748871Sjdp * The "path" argument is a pathname that is used only for error messages. 4834192Sjdp * 4934192Sjdp * The return value is a pointer to a newly-allocated Obj_Entry structure 5034192Sjdp * for the shared object. Returns NULL on failure. 5134192Sjdp */ 5234192SjdpObj_Entry * 5350609Sjdpmap_object(int fd, const char *path, const struct stat *sb) 5434192Sjdp{ 5534192Sjdp Obj_Entry *obj; 56115446Smdodd Elf_Ehdr *hdr; 57114625Sobrien int i; 5838816Sdfr Elf_Phdr *phdr; 5938816Sdfr Elf_Phdr *phlimit; 60105753Skan Elf_Phdr **segs; 6134192Sjdp int nsegs; 6238816Sdfr Elf_Phdr *phdyn; 6350610Sjdp Elf_Phdr *phinterp; 64133063Sdfr Elf_Phdr *phtls; 6534192Sjdp caddr_t mapbase; 6634192Sjdp size_t mapsize; 6738816Sdfr Elf_Addr base_vaddr; 6838816Sdfr Elf_Addr base_vlimit; 6934192Sjdp caddr_t base_addr; 70281452Skib int base_flags; 7138816Sdfr Elf_Off data_offset; 7238816Sdfr Elf_Addr data_vaddr; 7338816Sdfr Elf_Addr data_vlimit; 7434192Sjdp caddr_t data_addr; 75105753Skan int data_prot; 76107948Sdillon int data_flags; 7738816Sdfr Elf_Addr clear_vaddr; 7834192Sjdp caddr_t clear_addr; 79105753Skan caddr_t clear_page; 80168312Skan Elf_Addr phdr_vaddr; 81168312Skan size_t nclear, phsize; 8238816Sdfr Elf_Addr bss_vaddr; 8338816Sdfr Elf_Addr bss_vlimit; 8434192Sjdp caddr_t bss_addr; 85217153Skib Elf_Word stack_flags; 86230784Skib Elf_Addr relro_page; 87230784Skib size_t relro_size; 88232831Skib Elf_Addr note_start; 89232831Skib Elf_Addr note_end; 90290099Skib char *note_map; 91290099Skib size_t note_map_len; 9234192Sjdp 93115446Smdodd hdr = get_elf_header(fd, path); 94115446Smdodd if (hdr == NULL) 95115446Smdodd return (NULL); 9634192Sjdp 9734192Sjdp /* 9834192Sjdp * Scan the program header entries, and save key information. 9934192Sjdp * 100190883Skib * We expect that the loadable segments are ordered by load address. 10134192Sjdp */ 102115446Smdodd phdr = (Elf_Phdr *) ((char *)hdr + hdr->e_phoff); 103168312Skan phsize = hdr->e_phnum * sizeof (phdr[0]); 104115446Smdodd phlimit = phdr + hdr->e_phnum; 105105753Skan nsegs = -1; 106168312Skan phdyn = phinterp = phtls = NULL; 107168312Skan phdr_vaddr = 0; 108230784Skib relro_page = 0; 109230784Skib relro_size = 0; 110232831Skib note_start = 0; 111232831Skib note_end = 0; 112290099Skib note_map = NULL; 113115446Smdodd segs = alloca(sizeof(segs[0]) * hdr->e_phnum); 114217851Skib stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W; 11534192Sjdp while (phdr < phlimit) { 11634192Sjdp switch (phdr->p_type) { 11734192Sjdp 11850610Sjdp case PT_INTERP: 11950610Sjdp phinterp = phdr; 12050610Sjdp break; 12150610Sjdp 12234192Sjdp case PT_LOAD: 123105753Skan segs[++nsegs] = phdr; 124168312Skan if ((segs[nsegs]->p_align & (PAGE_SIZE - 1)) != 0) { 125105753Skan _rtld_error("%s: PT_LOAD segment %d not page-aligned", 126105753Skan path, nsegs); 127237058Skib goto error; 12848871Sjdp } 12934192Sjdp break; 13034192Sjdp 13134192Sjdp case PT_PHDR: 132168312Skan phdr_vaddr = phdr->p_vaddr; 133168312Skan phsize = phdr->p_memsz; 13434192Sjdp break; 13534192Sjdp 13634192Sjdp case PT_DYNAMIC: 13734192Sjdp phdyn = phdr; 13834192Sjdp break; 139133063Sdfr 140133063Sdfr case PT_TLS: 141133063Sdfr phtls = phdr; 142133063Sdfr break; 143217153Skib 144217153Skib case PT_GNU_STACK: 145217153Skib stack_flags = phdr->p_flags; 146217153Skib break; 147230784Skib 148230784Skib case PT_GNU_RELRO: 149230784Skib relro_page = phdr->p_vaddr; 150230784Skib relro_size = phdr->p_memsz; 151230784Skib break; 152232831Skib 153232831Skib case PT_NOTE: 154232856Skib if (phdr->p_offset > PAGE_SIZE || 155290099Skib phdr->p_offset + phdr->p_filesz > PAGE_SIZE) { 156290099Skib note_map_len = round_page(phdr->p_offset + 157290099Skib phdr->p_filesz) - trunc_page(phdr->p_offset); 158290099Skib note_map = mmap(NULL, note_map_len, PROT_READ, 159290099Skib MAP_PRIVATE, fd, trunc_page(phdr->p_offset)); 160290099Skib if (note_map == MAP_FAILED) { 161290099Skib _rtld_error("%s: error mapping PT_NOTE (%d)", path, errno); 162290099Skib goto error; 163290099Skib } 164290099Skib note_start = (Elf_Addr)(note_map + phdr->p_offset - 165290099Skib trunc_page(phdr->p_offset)); 166290099Skib } else { 167290099Skib note_start = (Elf_Addr)(char *)hdr + phdr->p_offset; 168290099Skib } 169232831Skib note_end = note_start + phdr->p_filesz; 170232831Skib break; 17134192Sjdp } 17234192Sjdp 17334192Sjdp ++phdr; 17434192Sjdp } 17534192Sjdp if (phdyn == NULL) { 17648871Sjdp _rtld_error("%s: object is not dynamically-linked", path); 177237058Skib goto error; 17834192Sjdp } 17934192Sjdp 180105753Skan if (nsegs < 0) { 18148871Sjdp _rtld_error("%s: too few PT_LOAD segments", path); 182237058Skib goto error; 18348871Sjdp } 18434192Sjdp 18534192Sjdp /* 18634192Sjdp * Map the entire address space of the object, to stake out our 18734192Sjdp * contiguous region, and to establish the base address for relocation. 18834192Sjdp */ 18934192Sjdp base_vaddr = trunc_page(segs[0]->p_vaddr); 190105753Skan base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz); 19134192Sjdp mapsize = base_vlimit - base_vaddr; 192247396Stijl base_addr = (caddr_t) base_vaddr; 193281452Skib base_flags = MAP_PRIVATE | MAP_ANON | MAP_NOCORE; 194281452Skib if (npagesizes > 1 && round_page(segs[0]->p_filesz) >= pagesizes[1]) 195281452Skib base_flags |= MAP_ALIGNED_SUPER; 19634192Sjdp 197281452Skib mapbase = mmap(base_addr, mapsize, PROT_NONE, base_flags, -1, 0); 19834192Sjdp if (mapbase == (caddr_t) -1) { 19948871Sjdp _rtld_error("%s: mmap of entire address space failed: %s", 200232974Skib path, rtld_strerror(errno)); 201237058Skib goto error; 20234192Sjdp } 20334192Sjdp if (base_addr != NULL && mapbase != base_addr) { 20448871Sjdp _rtld_error("%s: mmap returned wrong address: wanted %p, got %p", 20548871Sjdp path, base_addr, mapbase); 206237058Skib goto error1; 20734192Sjdp } 20834192Sjdp 209190883Skib for (i = 0; i <= nsegs; i++) { 210105753Skan /* Overlay the segment onto the proper region. */ 211105753Skan data_offset = trunc_page(segs[i]->p_offset); 212105753Skan data_vaddr = trunc_page(segs[i]->p_vaddr); 213105753Skan data_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_filesz); 214105753Skan data_addr = mapbase + (data_vaddr - base_vaddr); 215107948Sdillon data_prot = convert_prot(segs[i]->p_flags); 216107948Sdillon data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED; 217190885Skib if (mmap(data_addr, data_vlimit - data_vaddr, data_prot, 218237058Skib data_flags | MAP_PREFAULT_READ, fd, data_offset) == (caddr_t) -1) { 219232974Skib _rtld_error("%s: mmap of data failed: %s", path, 220232974Skib rtld_strerror(errno)); 221237058Skib goto error1; 222105753Skan } 22334192Sjdp 224195743Skib /* Do BSS setup */ 225195743Skib if (segs[i]->p_filesz != segs[i]->p_memsz) { 226195743Skib 227195743Skib /* Clear any BSS in the last page of the segment. */ 228195743Skib clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz; 229195743Skib clear_addr = mapbase + (clear_vaddr - base_vaddr); 230195743Skib clear_page = mapbase + (trunc_page(clear_vaddr) - base_vaddr); 231195743Skib 232195743Skib if ((nclear = data_vlimit - clear_vaddr) > 0) { 233195743Skib /* Make sure the end of the segment is writable */ 234195743Skib if ((data_prot & PROT_WRITE) == 0 && -1 == 235195743Skib mprotect(clear_page, PAGE_SIZE, data_prot|PROT_WRITE)) { 236105753Skan _rtld_error("%s: mprotect failed: %s", path, 237232974Skib rtld_strerror(errno)); 238237058Skib goto error1; 239195743Skib } 24034192Sjdp 241195743Skib memset(clear_addr, 0, nclear); 242105753Skan 243195743Skib /* Reset the data protection back */ 244195743Skib if ((data_prot & PROT_WRITE) == 0) 245195743Skib mprotect(clear_page, PAGE_SIZE, data_prot); 246195743Skib } 247105753Skan 248195743Skib /* Overlay the BSS segment onto the proper region. */ 249195743Skib bss_vaddr = data_vlimit; 250195743Skib bss_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_memsz); 251195743Skib bss_addr = mapbase + (bss_vaddr - base_vaddr); 252195743Skib if (bss_vlimit > bss_vaddr) { /* There is something to do */ 253225699Skib if (mmap(bss_addr, bss_vlimit - bss_vaddr, data_prot, 254225699Skib data_flags | MAP_ANON, -1, 0) == (caddr_t)-1) { 255225699Skib _rtld_error("%s: mmap of bss failed: %s", path, 256232974Skib rtld_strerror(errno)); 257237058Skib goto error1; 258195743Skib } 259105753Skan } 260105753Skan } 261195743Skib 262168312Skan if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff && 263168312Skan (data_vlimit - data_vaddr + data_offset) >= 264168312Skan (hdr->e_phoff + hdr->e_phnum * sizeof (Elf_Phdr))) { 265168312Skan phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset; 266168312Skan } 26734192Sjdp } 26834192Sjdp 26950608Sjdp obj = obj_new(); 27050609Sjdp if (sb != NULL) { 27150609Sjdp obj->dev = sb->st_dev; 27250609Sjdp obj->ino = sb->st_ino; 27350609Sjdp } 27434192Sjdp obj->mapbase = mapbase; 27534192Sjdp obj->mapsize = mapsize; 27634192Sjdp obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) - 27734192Sjdp base_vaddr; 27834192Sjdp obj->vaddrbase = base_vaddr; 27934192Sjdp obj->relocbase = mapbase - base_vaddr; 28050610Sjdp obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr); 281115446Smdodd if (hdr->e_entry != 0) 282115446Smdodd obj->entry = (caddr_t) (obj->relocbase + hdr->e_entry); 283168312Skan if (phdr_vaddr != 0) { 284168312Skan obj->phdr = (const Elf_Phdr *) (obj->relocbase + phdr_vaddr); 285168312Skan } else { 286168312Skan obj->phdr = malloc(phsize); 287168312Skan if (obj->phdr == NULL) { 288168312Skan obj_free(obj); 289168312Skan _rtld_error("%s: cannot allocate program header", path); 290237058Skib goto error1; 291168312Skan } 292168312Skan memcpy((char *)obj->phdr, (char *)hdr + hdr->e_phoff, phsize); 293168312Skan obj->phdr_alloc = true; 29434192Sjdp } 295168312Skan obj->phsize = phsize; 29650610Sjdp if (phinterp != NULL) 29750610Sjdp obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr); 298133063Sdfr if (phtls != NULL) { 299133063Sdfr tls_dtv_generation++; 300133063Sdfr obj->tlsindex = ++tls_max_index; 301133063Sdfr obj->tlssize = phtls->p_memsz; 302133063Sdfr obj->tlsalign = phtls->p_align; 303133063Sdfr obj->tlsinitsize = phtls->p_filesz; 304133063Sdfr obj->tlsinit = mapbase + phtls->p_vaddr; 305133063Sdfr } 306217153Skib obj->stack_flags = stack_flags; 307230784Skib obj->relro_page = obj->relocbase + trunc_page(relro_page); 308230784Skib obj->relro_size = round_page(relro_size); 309239019Skan if (note_start < note_end) 310239019Skan digest_notes(obj, note_start, note_end); 311290099Skib if (note_map != NULL) 312290099Skib munmap(note_map, note_map_len); 313237058Skib munmap(hdr, PAGE_SIZE); 314237058Skib return (obj); 315237058Skib 316237058Skiberror1: 317237058Skib munmap(mapbase, mapsize); 318237058Skiberror: 319290099Skib if (note_map != NULL && note_map != MAP_FAILED) 320290099Skib munmap(note_map, note_map_len); 321237058Skib munmap(hdr, PAGE_SIZE); 322237058Skib return (NULL); 32334192Sjdp} 32434192Sjdp 325115446Smdoddstatic Elf_Ehdr * 326237058Skibget_elf_header(int fd, const char *path) 327115446Smdodd{ 328237058Skib Elf_Ehdr *hdr; 329115446Smdodd 330237058Skib hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ, 331237058Skib fd, 0); 332237058Skib if (hdr == (Elf_Ehdr *)MAP_FAILED) { 333237058Skib _rtld_error("%s: read error: %s", path, rtld_strerror(errno)); 334237058Skib return (NULL); 335237058Skib } 336115446Smdodd 337237058Skib /* Make sure the file is valid */ 338237058Skib if (!IS_ELF(*hdr)) { 339237058Skib _rtld_error("%s: invalid file format", path); 340237058Skib goto error; 341237058Skib } 342237058Skib if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS || 343237058Skib hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 344237058Skib _rtld_error("%s: unsupported file layout", path); 345237058Skib goto error; 346237058Skib } 347237058Skib if (hdr->e_ident[EI_VERSION] != EV_CURRENT || 348237058Skib hdr->e_version != EV_CURRENT) { 349237058Skib _rtld_error("%s: unsupported file version", path); 350237058Skib goto error; 351237058Skib } 352237058Skib if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 353237058Skib _rtld_error("%s: unsupported file type", path); 354237058Skib goto error; 355237058Skib } 356237058Skib if (hdr->e_machine != ELF_TARG_MACH) { 357237058Skib _rtld_error("%s: unsupported machine", path); 358237058Skib goto error; 359237058Skib } 360115446Smdodd 361237058Skib /* 362237058Skib * We rely on the program header being in the first page. This is 363237058Skib * not strictly required by the ABI specification, but it seems to 364237058Skib * always true in practice. And, it simplifies things considerably. 365237058Skib */ 366237058Skib if (hdr->e_phentsize != sizeof(Elf_Phdr)) { 367237058Skib _rtld_error( 368237058Skib "%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path); 369237058Skib goto error; 370237058Skib } 371237058Skib if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) > 372237058Skib (size_t)PAGE_SIZE) { 373237058Skib _rtld_error("%s: program header too large", path); 374237058Skib goto error; 375237058Skib } 376237058Skib return (hdr); 377115446Smdodd 378237058Skiberror: 379237058Skib munmap(hdr, PAGE_SIZE); 380237058Skib return (NULL); 381115446Smdodd} 382115446Smdodd 38350608Sjdpvoid 38450608Sjdpobj_free(Obj_Entry *obj) 38550608Sjdp{ 38650608Sjdp Objlist_Entry *elm; 38750608Sjdp 388153515Skan if (obj->tls_done) 389142645Sdfr free_tls_offset(obj); 39050608Sjdp while (obj->needed != NULL) { 39150608Sjdp Needed_Entry *needed = obj->needed; 39250608Sjdp obj->needed = needed->next; 39350608Sjdp free(needed); 39450608Sjdp } 395153515Skan while (!STAILQ_EMPTY(&obj->names)) { 396153515Skan Name_Entry *entry = STAILQ_FIRST(&obj->names); 397153515Skan STAILQ_REMOVE_HEAD(&obj->names, link); 398153515Skan free(entry); 399153515Skan } 40050608Sjdp while (!STAILQ_EMPTY(&obj->dldags)) { 40150608Sjdp elm = STAILQ_FIRST(&obj->dldags); 40250608Sjdp STAILQ_REMOVE_HEAD(&obj->dldags, link); 40350608Sjdp free(elm); 40450608Sjdp } 40550608Sjdp while (!STAILQ_EMPTY(&obj->dagmembers)) { 40650608Sjdp elm = STAILQ_FIRST(&obj->dagmembers); 40750608Sjdp STAILQ_REMOVE_HEAD(&obj->dagmembers, link); 40850608Sjdp free(elm); 40950608Sjdp } 410168312Skan if (obj->vertab) 411168312Skan free(obj->vertab); 412168312Skan if (obj->origin_path) 413168312Skan free(obj->origin_path); 414189959Skib if (obj->z_origin) 415189959Skib free(obj->rpath); 416168312Skan if (obj->priv) 417168312Skan free(obj->priv); 418168312Skan if (obj->path) 419168312Skan free(obj->path); 420168312Skan if (obj->phdr_alloc) 421168312Skan free((void *)obj->phdr); 42250608Sjdp free(obj); 42350608Sjdp} 42450608Sjdp 42550608SjdpObj_Entry * 42650608Sjdpobj_new(void) 42750608Sjdp{ 42850608Sjdp Obj_Entry *obj; 42950608Sjdp 43050608Sjdp obj = CNEW(Obj_Entry); 43150608Sjdp STAILQ_INIT(&obj->dldags); 43250608Sjdp STAILQ_INIT(&obj->dagmembers); 433153515Skan STAILQ_INIT(&obj->names); 43450608Sjdp return obj; 43550608Sjdp} 43650608Sjdp 43734192Sjdp/* 43834192Sjdp * Given a set of ELF protection flags, return the corresponding protection 43934192Sjdp * flags for MMAP. 44034192Sjdp */ 441296939Skibint 442107948Sdillonconvert_prot(int elfflags) 44334192Sjdp{ 44434192Sjdp int prot = 0; 44534192Sjdp if (elfflags & PF_R) 44634192Sjdp prot |= PROT_READ; 44734192Sjdp if (elfflags & PF_W) 44834192Sjdp prot |= PROT_WRITE; 44934192Sjdp if (elfflags & PF_X) 45034192Sjdp prot |= PROT_EXEC; 45134192Sjdp return prot; 45234192Sjdp} 453107948Sdillon 454107948Sdillonstatic int 455107948Sdillonconvert_flags(int elfflags) 456107948Sdillon{ 457107948Sdillon int flags = MAP_PRIVATE; /* All mappings are private */ 458107948Sdillon 459107948Sdillon /* 460107948Sdillon * Readonly mappings are marked "MAP_NOCORE", because they can be 461107948Sdillon * reconstructed by a debugger. 462107948Sdillon */ 463107948Sdillon if (!(elfflags & PF_W)) 464107948Sdillon flags |= MAP_NOCORE; 465107948Sdillon return flags; 466107948Sdillon} 467