2 * Copyright 1996-1998 John D. Polstra.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/param.h>
41 static Elf_Ehdr *get_elf_header(int, const char *);
42 static int convert_flags(int); /* Elf flags -> mmap flags */
45 * Map a shared object into memory. The "fd" argument is a file descriptor,
46 * which must be open on the object and positioned at its beginning.
47 * The "path" argument is a pathname that is used only for error messages.
49 * The return value is a pointer to a newly-allocated Obj_Entry structure
50 * for the shared object. Returns NULL on failure.
53 map_object(int fd, const char *path, const struct stat *sb)
81 size_t nclear, phsize;
91 hdr = get_elf_header(fd, path);
95 if (__ld_sharedlib_base) {
96 shlib_base = (void *)(intptr_t)strtoul(__ld_sharedlib_base, NULL, 0);
102 * Scan the program header entries, and save key information.
104 * We expect that the loadable segments are ordered by load address.
106 phdr = (Elf_Phdr *) ((char *)hdr + hdr->e_phoff);
107 phsize = hdr->e_phnum * sizeof (phdr[0]);
108 phlimit = phdr + hdr->e_phnum;
110 phdyn = phinterp = phtls = NULL;
116 segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
117 stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
118 while (phdr < phlimit) {
119 switch (phdr->p_type) {
126 segs[++nsegs] = phdr;
127 if ((segs[nsegs]->p_align & (PAGE_SIZE - 1)) != 0) {
128 _rtld_error("%s: PT_LOAD segment %d not page-aligned",
135 phdr_vaddr = phdr->p_vaddr;
136 phsize = phdr->p_memsz;
148 stack_flags = phdr->p_flags;
152 relro_page = phdr->p_vaddr;
153 relro_size = phdr->p_memsz;
157 if (phdr->p_offset > PAGE_SIZE ||
158 phdr->p_offset + phdr->p_filesz > PAGE_SIZE)
160 note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
161 note_end = note_start + phdr->p_filesz;
168 _rtld_error("%s: object is not dynamically-linked", path);
173 _rtld_error("%s: too few PT_LOAD segments", path);
178 * Map the entire address space of the object, to stake out our
179 * contiguous region, and to establish the base address for relocation.
181 base_vaddr = trunc_page(segs[0]->p_vaddr);
182 base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
183 mapsize = base_vlimit - base_vaddr;
184 base_addr = (caddr_t) base_vaddr;
186 if (base_addr == NULL && shlib_base) {
187 size_t limit = 1024 * 256 * 1024;
190 for (offset = 0; offset < limit; offset += 256 * 1024) {
191 mapbase = mmap(shlib_base + offset, mapsize,
193 MAP_ANON | MAP_PRIVATE | MAP_NOCORE |
196 if (mapbase != MAP_FAILED)
200 mapbase = mmap(base_addr, mapsize,
202 MAP_ANON | MAP_PRIVATE | MAP_NOCORE,
205 if (mapbase == (caddr_t) -1) {
206 _rtld_error("%s: mmap of entire address space failed: %s",
207 path, rtld_strerror(errno));
210 if (base_addr != NULL && mapbase != base_addr) {
211 _rtld_error("%s: mmap returned wrong address: wanted %p, got %p",
212 path, base_addr, mapbase);
216 for (i = 0; i <= nsegs; i++) {
217 /* Overlay the segment onto the proper region. */
218 data_offset = trunc_page(segs[i]->p_offset);
219 data_vaddr = trunc_page(segs[i]->p_vaddr);
220 data_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_filesz);
221 data_addr = mapbase + (data_vaddr - base_vaddr);
222 data_prot = convert_prot(segs[i]->p_flags);
223 data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
224 if (mmap(data_addr, data_vlimit - data_vaddr, data_prot,
225 data_flags, fd, data_offset) == (caddr_t) -1) {
226 _rtld_error("%s: mmap of data failed: %s", path,
227 rtld_strerror(errno));
232 if (segs[i]->p_filesz != segs[i]->p_memsz) {
234 /* Clear any BSS in the last page of the segment. */
235 clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz;
236 clear_addr = mapbase + (clear_vaddr - base_vaddr);
237 clear_page = mapbase + (trunc_page(clear_vaddr) - base_vaddr);
239 if ((nclear = data_vlimit - clear_vaddr) > 0) {
240 /* Make sure the end of the segment is writable */
241 if ((data_prot & PROT_WRITE) == 0 && -1 ==
242 mprotect(clear_page, PAGE_SIZE, data_prot|PROT_WRITE)) {
243 _rtld_error("%s: mprotect failed: %s", path,
244 rtld_strerror(errno));
248 memset(clear_addr, 0, nclear);
251 * reset the data protection back, enable the segment to be
252 * coredumped since we modified it.
254 if ((data_prot & PROT_WRITE) == 0) {
255 madvise(clear_page, PAGE_SIZE, MADV_CORE);
256 mprotect(clear_page, PAGE_SIZE, data_prot);
260 /* Overlay the BSS segment onto the proper region. */
261 bss_vaddr = data_vlimit;
262 bss_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_memsz);
263 bss_addr = mapbase + (bss_vaddr - base_vaddr);
264 if (bss_vlimit > bss_vaddr) { /* There is something to do */
265 if (mmap(bss_addr, bss_vlimit - bss_vaddr, data_prot,
266 data_flags | MAP_ANON, -1, 0) == (caddr_t)-1) {
267 _rtld_error("%s: mmap of bss failed: %s", path,
268 rtld_strerror(errno));
274 if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff &&
275 (data_vlimit - data_vaddr + data_offset) >=
276 (hdr->e_phoff + hdr->e_phnum * sizeof (Elf_Phdr))) {
277 phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset;
283 obj->dev = sb->st_dev;
284 obj->ino = sb->st_ino;
286 obj->mapbase = mapbase;
287 obj->mapsize = mapsize;
288 obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) -
290 obj->vaddrbase = base_vaddr;
291 obj->relocbase = mapbase - base_vaddr;
292 obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr);
293 if (hdr->e_entry != 0)
294 obj->entry = (caddr_t) (obj->relocbase + hdr->e_entry);
295 if (phdr_vaddr != 0) {
296 obj->phdr = (const Elf_Phdr *) (obj->relocbase + phdr_vaddr);
298 obj->phdr = malloc(phsize);
299 if (obj->phdr == NULL) {
301 _rtld_error("%s: cannot allocate program header", path);
304 memcpy((char *)obj->phdr, (char *)hdr + hdr->e_phoff, phsize);
305 obj->phdr_alloc = true;
307 obj->phsize = phsize;
308 if (phinterp != NULL)
309 obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr);
311 tls_dtv_generation++;
312 obj->tlsindex = ++tls_max_index;
313 obj->tlssize = phtls->p_memsz;
314 obj->tlsalign = phtls->p_align;
315 obj->tlsinitsize = phtls->p_filesz;
316 obj->tlsinit = mapbase + phtls->p_vaddr;
318 obj->stack_flags = stack_flags;
320 obj->relro_page = obj->relocbase + trunc_page(relro_page);
321 obj->relro_size = round_page(relro_size);
323 if (note_start < note_end)
324 digest_notes(obj, note_start, note_end);
325 munmap(hdr, PAGE_SIZE);
329 munmap(mapbase, mapsize);
331 munmap(hdr, PAGE_SIZE);
336 get_elf_header(int fd, const char *path)
340 /* DragonFly mmap does not have MAP_PREFAULT_READ */
341 hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0);
342 if (hdr == (Elf_Ehdr *)MAP_FAILED) {
343 _rtld_error("%s: read error: %s", path, rtld_strerror(errno));
347 /* Make sure the file is valid */
349 _rtld_error("%s: invalid file format", path);
352 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
353 hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
354 _rtld_error("%s: unsupported file layout", path);
357 if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
358 hdr->e_version != EV_CURRENT) {
359 _rtld_error("%s: unsupported file version", path);
362 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
363 _rtld_error("%s: unsupported file type", path);
366 if (hdr->e_machine != ELF_TARG_MACH) {
367 _rtld_error("%s: unsupported machine", path);
372 * We rely on the program header being in the first page. This is
373 * not strictly required by the ABI specification, but it seems to
374 * always true in practice. And, it simplifies things considerably.
376 if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
378 "%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
381 if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) >
383 _rtld_error("%s: program header too large", path);
389 munmap(hdr, PAGE_SIZE);
394 obj_free(Obj_Entry *obj)
399 free_tls_offset(obj);
400 while (obj->needed != NULL) {
401 Needed_Entry *needed = obj->needed;
402 obj->needed = needed->next;
405 while (!STAILQ_EMPTY(&obj->names)) {
406 Name_Entry *entry = STAILQ_FIRST(&obj->names);
407 STAILQ_REMOVE_HEAD(&obj->names, link);
410 while (!STAILQ_EMPTY(&obj->dldags)) {
411 elm = STAILQ_FIRST(&obj->dldags);
412 STAILQ_REMOVE_HEAD(&obj->dldags, link);
415 while (!STAILQ_EMPTY(&obj->dagmembers)) {
416 elm = STAILQ_FIRST(&obj->dagmembers);
417 STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
422 if (obj->origin_path)
423 free(obj->origin_path);
431 free((void *)obj->phdr);
440 obj = CNEW(Obj_Entry);
441 STAILQ_INIT(&obj->dldags);
442 STAILQ_INIT(&obj->dagmembers);
443 STAILQ_INIT(&obj->names);
448 * Given a set of ELF protection flags, return the corresponding protection
452 convert_prot(int elfflags)
465 convert_flags(int elfflags)
467 int flags = MAP_PRIVATE; /* All mappings are private */
470 * Readonly mappings are marked "MAP_NOCORE", because they can be
471 * reconstructed by a debugger.
473 if (!(elfflags & PF_W))