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