1 /****************************************************************************/
2 /*
3 * QEMU bFLT binary loader. Based on linux/fs/binfmt_flat.c
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 *
18 * Copyright (C) 2006 CodeSourcery.
19 * Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
20 * Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
21 * Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
22 * Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
23 * based heavily on:
24 *
25 * linux/fs/binfmt_aout.c:
26 * Copyright (C) 1991, 1992, 1996 Linus Torvalds
27 * linux/fs/binfmt_flat.c for 2.0 kernel
28 * Copyright (C) 1998 Kenneth Albanowski <kjahds@kjahds.com>
29 * JAN/99 -- coded full program relocation (gerg@snapgear.com)
30 */
31
32 /****************************************************************************/
33
34 #include "qemu/osdep.h"
35
36 #include "qemu.h"
37 #include "exec/page-protection.h"
38 #include "exec/mmap-lock.h"
39 #include "user-internals.h"
40 #include "loader.h"
41 #include "user-mmap.h"
42 #include "flat.h"
43 #include "target_flat.h"
44
45 //#define DEBUG
46
47 #ifdef DEBUG
48 #define DBG_FLT(...) printf(__VA_ARGS__)
49 #else
50 #define DBG_FLT(...)
51 #endif
52
53 #define RELOC_FAILED 0xff00ff01 /* Relocation incorrect somewhere */
54 #define UNLOADED_LIB 0x7ff000ff /* Placeholder for unused library */
55
56 struct lib_info {
57 abi_ulong start_code; /* Start of text segment */
58 abi_ulong start_data; /* Start of data segment */
59 abi_ulong end_data; /* Start of bss section */
60 abi_ulong start_brk; /* End of data segment */
61 abi_ulong text_len; /* Length of text segment */
62 abi_ulong entry; /* Start address for this module */
63 abi_ulong build_date; /* When this one was compiled */
64 short loaded; /* Has this library been loaded? */
65 };
66
67 struct linux_binprm;
68
69 /****************************************************************************/
70 /*
71 * create_flat_tables() parses the env- and arg-strings in new user
72 * memory and creates the pointer tables from them, and puts their
73 * addresses on the "stack", returning the new stack pointer value.
74 */
75
76 /* Push a block of strings onto the guest stack. */
copy_strings(abi_ulong p,int n,char ** s)77 static abi_ulong copy_strings(abi_ulong p, int n, char **s)
78 {
79 int len;
80
81 while (n-- > 0) {
82 len = strlen(s[n]) + 1;
83 p -= len;
84 memcpy_to_target(p, s[n], len);
85 }
86
87 return p;
88 }
89
target_pread(int fd,abi_ulong ptr,abi_ulong len,abi_ulong offset)90 static int target_pread(int fd, abi_ulong ptr, abi_ulong len,
91 abi_ulong offset)
92 {
93 void *buf;
94 int ret;
95
96 buf = lock_user(VERIFY_WRITE, ptr, len, 0);
97 if (!buf) {
98 return -EFAULT;
99 }
100 ret = pread(fd, buf, len, offset);
101 if (ret < 0) {
102 ret = -errno;
103 }
104 unlock_user(buf, ptr, len);
105 return ret;
106 }
107
108 /****************************************************************************/
109
110 static abi_ulong
calc_reloc(abi_ulong r,struct lib_info * p,int curid,int internalp)111 calc_reloc(abi_ulong r, struct lib_info *p, int curid, int internalp)
112 {
113 abi_ulong addr;
114 int id;
115 abi_ulong start_brk;
116 abi_ulong start_data;
117 abi_ulong text_len;
118 abi_ulong start_code;
119
120 id = 0;
121
122 start_brk = p[id].start_brk;
123 start_data = p[id].start_data;
124 start_code = p[id].start_code;
125 text_len = p[id].text_len;
126
127 if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
128 fprintf(stderr, "BINFMT_FLAT: reloc outside program 0x%x "
129 "(0 - 0x%x/0x%x)\n",
130 (int) r,(int)(start_brk-start_code),(int)text_len);
131 goto failed;
132 }
133
134 if (r < text_len) /* In text segment */
135 addr = r + start_code;
136 else /* In data segment */
137 addr = r - text_len + start_data;
138
139 /* Range checked already above so doing the range tests is redundant...*/
140 return(addr);
141
142 failed:
143 abort();
144 return RELOC_FAILED;
145 }
146
147 /****************************************************************************/
148
149 /* ??? This does not handle endianness correctly. */
old_reloc(struct lib_info * libinfo,uint32_t rl)150 static void old_reloc(struct lib_info *libinfo, uint32_t rl)
151 {
152 #ifdef DEBUG
153 const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
154 #endif
155 uint32_t *ptr;
156 uint32_t offset;
157 int reloc_type;
158
159 offset = rl & 0x3fffffff;
160 reloc_type = rl >> 30;
161 /* ??? How to handle this? */
162 #if defined(CONFIG_COLDFIRE)
163 ptr = (uint32_t *) ((unsigned long) libinfo->start_code + offset);
164 #else
165 ptr = (uint32_t *) ((unsigned long) libinfo->start_data + offset);
166 #endif
167
168 #ifdef DEBUG
169 fprintf(stderr, "Relocation of variable at DATASEG+%x "
170 "(address %p, currently %x) into segment %s\n",
171 offset, ptr, (int)*ptr, segment[reloc_type]);
172 #endif
173
174 switch (reloc_type) {
175 case OLD_FLAT_RELOC_TYPE_TEXT:
176 *ptr += libinfo->start_code;
177 break;
178 case OLD_FLAT_RELOC_TYPE_DATA:
179 *ptr += libinfo->start_data;
180 break;
181 case OLD_FLAT_RELOC_TYPE_BSS:
182 *ptr += libinfo->end_data;
183 break;
184 default:
185 fprintf(stderr, "BINFMT_FLAT: Unknown relocation type=%x\n",
186 reloc_type);
187 break;
188 }
189 DBG_FLT("Relocation became %x\n", (int)*ptr);
190 }
191
192 /****************************************************************************/
193
load_flat_file(struct linux_binprm * bprm,struct lib_info * libinfo,int id,abi_ulong * extra_stack)194 static int load_flat_file(struct linux_binprm * bprm,
195 struct lib_info *libinfo, int id, abi_ulong *extra_stack)
196 {
197 struct flat_hdr * hdr;
198 abi_ulong textpos = 0, datapos = 0;
199 abi_long result;
200 abi_ulong realdatastart = 0;
201 abi_ulong text_len, data_len, bss_len, stack_len, flags;
202 abi_ulong extra;
203 abi_ulong reloc = 0, rp;
204 int i, rev, relocs = 0;
205 abi_ulong fpos;
206 abi_ulong start_code;
207 abi_ulong indx_len;
208
209 hdr = ((struct flat_hdr *) bprm->buf); /* exec-header */
210
211 text_len = ntohl(hdr->data_start);
212 data_len = ntohl(hdr->data_end) - ntohl(hdr->data_start);
213 bss_len = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
214 stack_len = ntohl(hdr->stack_size);
215 if (extra_stack) {
216 stack_len += *extra_stack;
217 *extra_stack = stack_len;
218 }
219 relocs = ntohl(hdr->reloc_count);
220 flags = ntohl(hdr->flags);
221 rev = ntohl(hdr->rev);
222
223 DBG_FLT("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
224
225 if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
226 fprintf(stderr, "BINFMT_FLAT: bad magic/rev (0x%x, need 0x%x)\n",
227 rev, (int) FLAT_VERSION);
228 return -ENOEXEC;
229 }
230
231 /* Don't allow old format executables to use shared libraries */
232 if (rev == OLD_FLAT_VERSION && id != 0) {
233 fprintf(stderr, "BINFMT_FLAT: shared libraries are not available\n");
234 return -ENOEXEC;
235 }
236
237 /*
238 * fix up the flags for the older format, there were all kinds
239 * of endian hacks, this only works for the simple cases
240 */
241 if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
242 flags = FLAT_FLAG_RAM;
243
244 if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
245 fprintf(stderr, "ZFLAT executables are not supported\n");
246 return -ENOEXEC;
247 }
248
249 /*
250 * calculate the extra space we need to map in
251 */
252 extra = relocs * sizeof(abi_ulong);
253 if (extra < bss_len + stack_len)
254 extra = bss_len + stack_len;
255
256 /* Add space for library base pointers. Make sure this does not
257 misalign the doesn't misalign the data segment. */
258 indx_len = MAX_SHARED_LIBS * sizeof(abi_ulong);
259 indx_len = (indx_len + 15) & ~(abi_ulong)15;
260
261 /*
262 * Allocate the address space.
263 */
264 probe_guest_base(bprm->filename, 0,
265 text_len + data_len + extra + indx_len - 1);
266
267 /*
268 * there are a couple of cases here, the separate code/data
269 * case, and then the fully copied to RAM case which lumps
270 * it all together.
271 */
272 if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
273 /*
274 * this should give us a ROM ptr, but if it doesn't we don't
275 * really care
276 */
277 DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
278
279 textpos = target_mmap(0, text_len, PROT_READ|PROT_EXEC,
280 MAP_PRIVATE, bprm->src.fd, 0);
281 if (textpos == -1) {
282 fprintf(stderr, "Unable to mmap process text\n");
283 return -1;
284 }
285
286 realdatastart = target_mmap(0, data_len + extra + indx_len,
287 PROT_READ|PROT_WRITE|PROT_EXEC,
288 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
289
290 if (realdatastart == -1) {
291 fprintf(stderr, "Unable to allocate RAM for process data\n");
292 return realdatastart;
293 }
294 datapos = realdatastart + indx_len;
295
296 DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
297 (int)(data_len + bss_len + stack_len), (int)datapos);
298
299 fpos = ntohl(hdr->data_start);
300 result = target_pread(bprm->src.fd, datapos,
301 data_len + (relocs * sizeof(abi_ulong)),
302 fpos);
303 if (result < 0) {
304 fprintf(stderr, "Unable to read data+bss\n");
305 return result;
306 }
307
308 reloc = datapos + (ntohl(hdr->reloc_start) - text_len);
309
310 } else {
311
312 textpos = target_mmap(0, text_len + data_len + extra + indx_len,
313 PROT_READ | PROT_EXEC | PROT_WRITE,
314 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
315 if (textpos == -1 ) {
316 fprintf(stderr, "Unable to allocate RAM for process text/data\n");
317 return -1;
318 }
319
320 realdatastart = textpos + ntohl(hdr->data_start);
321 datapos = realdatastart + indx_len;
322 reloc = (textpos + ntohl(hdr->reloc_start) + indx_len);
323
324 result = target_pread(bprm->src.fd, textpos,
325 text_len, 0);
326 if (result >= 0) {
327 result = target_pread(bprm->src.fd, datapos,
328 data_len + (relocs * sizeof(abi_ulong)),
329 ntohl(hdr->data_start));
330 }
331 if (result < 0) {
332 fprintf(stderr, "Unable to read code+data+bss\n");
333 return result;
334 }
335 }
336
337 DBG_FLT("Mapping is 0x%x, Entry point is 0x%x, data_start is 0x%x\n",
338 (int)textpos, 0x00ffffff&ntohl(hdr->entry),
339 ntohl(hdr->data_start));
340
341 /* The main program needs a little extra setup in the task structure */
342 start_code = textpos + sizeof (struct flat_hdr);
343
344 DBG_FLT("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
345 id ? "Lib" : "Load", bprm->filename,
346 (int) start_code, (int) (textpos + text_len),
347 (int) datapos,
348 (int) (datapos + data_len),
349 (int) (datapos + data_len),
350 (int) (((datapos + data_len + bss_len) + 3) & ~3));
351
352 text_len -= sizeof(struct flat_hdr); /* the real code len */
353
354 /* Store the current module values into the global library structure */
355 libinfo[id].start_code = start_code;
356 libinfo[id].start_data = datapos;
357 libinfo[id].end_data = datapos + data_len;
358 libinfo[id].start_brk = datapos + data_len + bss_len;
359 libinfo[id].text_len = text_len;
360 libinfo[id].loaded = 1;
361 libinfo[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
362 libinfo[id].build_date = ntohl(hdr->build_date);
363
364 /*
365 * We just load the allocations into some temporary memory to
366 * help simplify all this mumbo jumbo
367 *
368 * We've got two different sections of relocation entries.
369 * The first is the GOT which resides at the beginning of the data segment
370 * and is terminated with a -1. This one can be relocated in place.
371 * The second is the extra relocation entries tacked after the image's
372 * data segment. These require a little more processing as the entry is
373 * really an offset into the image which contains an offset into the
374 * image.
375 */
376 if (flags & FLAT_FLAG_GOTPIC) {
377 rp = datapos;
378 while (1) {
379 abi_ulong addr;
380 if (get_user_ual(addr, rp))
381 return -EFAULT;
382 if (addr == -1)
383 break;
384 if (addr) {
385 addr = calc_reloc(addr, libinfo, id, 0);
386 if (addr == RELOC_FAILED)
387 return -ENOEXEC;
388 if (put_user_ual(addr, rp))
389 return -EFAULT;
390 }
391 rp += sizeof(abi_ulong);
392 }
393 }
394
395 /*
396 * Now run through the relocation entries.
397 * We've got to be careful here as C++ produces relocatable zero
398 * entries in the constructor and destructor tables which are then
399 * tested for being not zero (which will always occur unless we're
400 * based from address zero). This causes an endless loop as __start
401 * is at zero. The solution used is to not relocate zero addresses.
402 * This has the negative side effect of not allowing a global data
403 * reference to be statically initialised to _stext (I've moved
404 * __start to address 4 so that is okay).
405 */
406 if (rev > OLD_FLAT_VERSION) {
407 abi_ulong persistent = 0;
408 for (i = 0; i < relocs; i++) {
409 abi_ulong addr, relval;
410
411 /* Get the address of the pointer to be
412 relocated (of course, the address has to be
413 relocated first). */
414 if (get_user_ual(relval, reloc + i * sizeof(abi_ulong)))
415 return -EFAULT;
416 relval = ntohl(relval);
417 if (flat_set_persistent(relval, &persistent))
418 continue;
419 addr = flat_get_relocate_addr(relval);
420 rp = calc_reloc(addr, libinfo, id, 1);
421 if (rp == RELOC_FAILED)
422 return -ENOEXEC;
423
424 /* Get the pointer's value. */
425 if (get_user_ual(addr, rp))
426 return -EFAULT;
427 addr = flat_get_addr_from_rp(addr, relval, flags, &persistent);
428 if (addr != 0) {
429 /*
430 * Do the relocation. PIC relocs in the data section are
431 * already in target order
432 */
433 if ((flags & FLAT_FLAG_GOTPIC) == 0)
434 addr = ntohl(addr);
435 addr = calc_reloc(addr, libinfo, id, 0);
436 if (addr == RELOC_FAILED)
437 return -ENOEXEC;
438
439 /* Write back the relocated pointer. */
440 if (flat_put_addr_at_rp(rp, addr, relval))
441 return -EFAULT;
442 }
443 }
444 } else {
445 for (i = 0; i < relocs; i++) {
446 abi_ulong relval;
447 if (get_user_ual(relval, reloc + i * sizeof(abi_ulong)))
448 return -EFAULT;
449 old_reloc(&libinfo[0], relval);
450 }
451 }
452
453 /* zero the BSS. */
454 memset(g2h_untagged(datapos + data_len), 0, bss_len);
455
456 return 0;
457 }
458
459
460 /****************************************************************************/
load_flt_binary(struct linux_binprm * bprm,struct image_info * info)461 int load_flt_binary(struct linux_binprm *bprm, struct image_info *info)
462 {
463 struct lib_info libinfo[MAX_SHARED_LIBS];
464 abi_ulong p;
465 abi_ulong stack_len;
466 abi_ulong start_addr;
467 abi_ulong sp;
468 int res;
469 int i, j;
470
471 memset(libinfo, 0, sizeof(libinfo));
472 /*
473 * We have to add the size of our arguments to our stack size
474 * otherwise it's too easy for users to create stack overflows
475 * by passing in a huge argument list. And yes, we have to be
476 * pedantic and include space for the argv/envp array as it may have
477 * a lot of entries.
478 */
479 stack_len = 0;
480 for (i = 0; i < bprm->argc; ++i) {
481 /* the argv strings */
482 stack_len += strlen(bprm->argv[i]);
483 }
484 for (i = 0; i < bprm->envc; ++i) {
485 /* the envp strings */
486 stack_len += strlen(bprm->envp[i]);
487 }
488 stack_len += (bprm->argc + 1) * 4; /* the argv array */
489 stack_len += (bprm->envc + 1) * 4; /* the envp array */
490
491
492 mmap_lock();
493 res = load_flat_file(bprm, libinfo, 0, &stack_len);
494 mmap_unlock();
495
496 if (is_error(res)) {
497 return res;
498 }
499
500 /* Update data segment pointers for all libraries */
501 for (i=0; i<MAX_SHARED_LIBS; i++) {
502 if (libinfo[i].loaded) {
503 abi_ulong seg;
504 seg = libinfo[i].start_data;
505 for (j=0; j<MAX_SHARED_LIBS; j++) {
506 seg -= 4;
507 /* FIXME - handle put_user() failures */
508 if (put_user_ual(libinfo[j].loaded
509 ? libinfo[j].start_data
510 : UNLOADED_LIB,
511 seg))
512 return -EFAULT;
513 }
514 }
515 }
516
517 p = ((libinfo[0].start_brk + stack_len + 3) & ~3) - 4;
518 DBG_FLT("p=%x\n", (int)p);
519
520 /* Copy argv/envp. */
521 p = copy_strings(p, bprm->envc, bprm->envp);
522 p = copy_strings(p, bprm->argc, bprm->argv);
523 /* Align stack. */
524 sp = p & ~(abi_ulong)(sizeof(abi_ulong) - 1);
525 /* Enforce final stack alignment of 16 bytes. This is sufficient
526 for all current targets, and excess alignment is harmless. */
527 stack_len = bprm->envc + bprm->argc + 2;
528 stack_len += flat_argvp_envp_on_stack() ? 2 : 0; /* argv, argp */
529 stack_len += 1; /* argc */
530 stack_len *= sizeof(abi_ulong);
531 sp -= (sp - stack_len) & 15;
532 sp = loader_build_argptr(bprm->envc, bprm->argc, sp, p,
533 flat_argvp_envp_on_stack());
534
535 /* Fake some return addresses to ensure the call chain will
536 * initialise library in order for us. We are required to call
537 * lib 1 first, then 2, ... and finally the main program (id 0).
538 */
539 start_addr = libinfo[0].entry;
540
541 /* Stash our initial stack pointer into the mm structure */
542 info->start_code = libinfo[0].start_code;
543 info->end_code = libinfo[0].start_code + libinfo[0].text_len;
544 info->start_data = libinfo[0].start_data;
545 info->end_data = libinfo[0].end_data;
546 info->brk = libinfo[0].start_brk;
547 info->start_stack = sp;
548 info->stack_limit = libinfo[0].start_brk;
549 info->entry = start_addr;
550 info->code_offset = info->start_code;
551 info->data_offset = info->start_data - libinfo[0].text_len;
552
553 DBG_FLT("start_thread(entry=0x%x, start_stack=0x%x)\n",
554 (int)info->entry, (int)info->start_stack);
555
556 return 0;
557 }
558