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