blob: 07a4996cca3f76c03a1a6434decc88f0dacfdc42 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * binfmt_misc.c
3 *
4 * Copyright (C) 1997 Richard Günther
5 *
6 * binfmt_misc detects binaries via a magic or filename extension and invokes
7 * a specified wrapper. This should obsolete binfmt_java, binfmt_em86 and
8 * binfmt_mz.
9 *
10 * 1997-04-25 first version
11 * [...]
12 * 1997-05-19 cleanup
13 * 1997-06-26 hpa: pass the real filename rather than argv[0]
14 * 1997-06-30 minor cleanup
15 * 1997-08-09 removed extension stripping, locking cleanup
16 * 2001-02-28 AV: rewritten into something that resembles C. Original didn't.
17 */
18
19#include <linux/module.h>
20#include <linux/init.h>
21
22#include <linux/binfmts.h>
23#include <linux/slab.h>
24#include <linux/ctype.h>
25#include <linux/file.h>
26#include <linux/pagemap.h>
27#include <linux/namei.h>
28#include <linux/mount.h>
29#include <linux/syscalls.h>
30
31#include <asm/uaccess.h>
32
33enum {
34 VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
35};
36
37static LIST_HEAD(entries);
38static int enabled = 1;
39
40enum {Enabled, Magic};
41#define MISC_FMT_PRESERVE_ARGV0 (1<<31)
42#define MISC_FMT_OPEN_BINARY (1<<30)
43#define MISC_FMT_CREDENTIALS (1<<29)
44
45typedef struct {
46 struct list_head list;
47 unsigned long flags; /* type, status, etc. */
48 int offset; /* offset of magic */
49 int size; /* size of magic/mask */
50 char *magic; /* magic or filename extension */
51 char *mask; /* mask, NULL for exact match */
52 char *interpreter; /* filename of interpreter */
53 char *name;
54 struct dentry *dentry;
55} Node;
56
57static DEFINE_RWLOCK(entries_lock);
58static struct vfsmount *bm_mnt;
59static int entry_count;
60
61/*
62 * Check if we support the binfmt
63 * if we do, return the node, else NULL
64 * locking is done in load_misc_binary
65 */
66static Node *check_file(struct linux_binprm *bprm)
67{
68 char *p = strrchr(bprm->interp, '.');
69 struct list_head *l;
70
71 list_for_each(l, &entries) {
72 Node *e = list_entry(l, Node, list);
73 char *s;
74 int j;
75
76 if (!test_bit(Enabled, &e->flags))
77 continue;
78
79 if (!test_bit(Magic, &e->flags)) {
80 if (p && !strcmp(e->magic, p + 1))
81 return e;
82 continue;
83 }
84
85 s = bprm->buf + e->offset;
86 if (e->mask) {
87 for (j = 0; j < e->size; j++)
88 if ((*s++ ^ e->magic[j]) & e->mask[j])
89 break;
90 } else {
91 for (j = 0; j < e->size; j++)
92 if ((*s++ ^ e->magic[j]))
93 break;
94 }
95 if (j == e->size)
96 return e;
97 }
98 return NULL;
99}
100
101/*
102 * the loader itself
103 */
104static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)
105{
106 Node *fmt;
107 struct file * interp_file = NULL;
108 char iname[BINPRM_BUF_SIZE];
109 char *iname_addr = iname;
110 int retval;
111 int fd_binary = -1;
112 struct files_struct *files = NULL;
113
114 retval = -ENOEXEC;
115 if (!enabled)
116 goto _ret;
117
118 /* to keep locking time low, we copy the interpreter string */
119 read_lock(&entries_lock);
120 fmt = check_file(bprm);
121 if (fmt)
122 strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
123 read_unlock(&entries_lock);
124 if (!fmt)
125 goto _ret;
126
127 if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
128 remove_arg_zero(bprm);
129 }
130
131 if (fmt->flags & MISC_FMT_OPEN_BINARY) {
132
133 files = current->files;
134 retval = unshare_files();
135 if (retval < 0)
136 goto _ret;
137 if (files == current->files) {
138 put_files_struct(files);
139 files = NULL;
140 }
141 /* if the binary should be opened on behalf of the
142 * interpreter than keep it open and assign descriptor
143 * to it */
144 fd_binary = get_unused_fd();
145 if (fd_binary < 0) {
146 retval = fd_binary;
147 goto _unshare;
148 }
149 fd_install(fd_binary, bprm->file);
150
151 /* if the binary is not readable than enforce mm->dumpable=0
152 regardless of the interpreter's permissions */
Christoph Hellwig8c744fb2005-11-08 21:35:04 -0800153 if (file_permission(bprm->file, MAY_READ))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
155
156 allow_write_access(bprm->file);
157 bprm->file = NULL;
158
159 /* mark the bprm that fd should be passed to interp */
160 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
161 bprm->interp_data = fd_binary;
162
163 } else {
164 allow_write_access(bprm->file);
165 fput(bprm->file);
166 bprm->file = NULL;
167 }
168 /* make argv[1] be the path to the binary */
169 retval = copy_strings_kernel (1, &bprm->interp, bprm);
170 if (retval < 0)
171 goto _error;
172 bprm->argc++;
173
174 /* add the interp as argv[0] */
175 retval = copy_strings_kernel (1, &iname_addr, bprm);
176 if (retval < 0)
177 goto _error;
178 bprm->argc ++;
179
180 bprm->interp = iname; /* for binfmt_script */
181
182 interp_file = open_exec (iname);
183 retval = PTR_ERR (interp_file);
184 if (IS_ERR (interp_file))
185 goto _error;
186
187 bprm->file = interp_file;
188 if (fmt->flags & MISC_FMT_CREDENTIALS) {
189 /*
190 * No need to call prepare_binprm(), it's already been
191 * done. bprm->buf is stale, update from interp_file.
192 */
193 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
194 retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
195 } else
196 retval = prepare_binprm (bprm);
197
198 if (retval < 0)
199 goto _error;
200
201 retval = search_binary_handler (bprm, regs);
202 if (retval < 0)
203 goto _error;
204
205 if (files) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 put_files_struct(files);
207 files = NULL;
208 }
209_ret:
210 return retval;
211_error:
212 if (fd_binary > 0)
213 sys_close(fd_binary);
214 bprm->interp_flags = 0;
215 bprm->interp_data = 0;
216_unshare:
217 if (files) {
218 put_files_struct(current->files);
219 current->files = files;
220 }
221 goto _ret;
222}
223
224/* Command parsers */
225
226/*
227 * parses and copies one argument enclosed in del from *sp to *dp,
228 * recognising the \x special.
229 * returns pointer to the copied argument or NULL in case of an
230 * error (and sets err) or null argument length.
231 */
232static char *scanarg(char *s, char del)
233{
234 char c;
235
236 while ((c = *s++) != del) {
237 if (c == '\\' && *s == 'x') {
238 s++;
239 if (!isxdigit(*s++))
240 return NULL;
241 if (!isxdigit(*s++))
242 return NULL;
243 }
244 }
245 return s;
246}
247
248static int unquote(char *from)
249{
250 char c = 0, *s = from, *p = from;
251
252 while ((c = *s++) != '\0') {
253 if (c == '\\' && *s == 'x') {
254 s++;
255 c = toupper(*s++);
256 *p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4;
257 c = toupper(*s++);
258 *p++ |= c - (isdigit(c) ? '0' : 'A' - 10);
259 continue;
260 }
261 *p++ = c;
262 }
263 return p - from;
264}
265
Arjan van de Ven858119e2006-01-14 13:20:43 -0800266static char * check_special_flags (char * sfs, Node * e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
268 char * p = sfs;
269 int cont = 1;
270
271 /* special flags */
272 while (cont) {
273 switch (*p) {
274 case 'P':
275 p++;
276 e->flags |= MISC_FMT_PRESERVE_ARGV0;
277 break;
278 case 'O':
279 p++;
280 e->flags |= MISC_FMT_OPEN_BINARY;
281 break;
282 case 'C':
283 p++;
284 /* this flags also implies the
285 open-binary flag */
286 e->flags |= (MISC_FMT_CREDENTIALS |
287 MISC_FMT_OPEN_BINARY);
288 break;
289 default:
290 cont = 0;
291 }
292 }
293
294 return p;
295}
296/*
297 * This registers a new binary format, it recognises the syntax
298 * ':name:type:offset:magic:mask:interpreter:flags'
299 * where the ':' is the IFS, that can be chosen with the first char
300 */
301static Node *create_entry(const char __user *buffer, size_t count)
302{
303 Node *e;
304 int memsize, err;
305 char *buf, *p;
306 char del;
307
308 /* some sanity checks */
309 err = -EINVAL;
310 if ((count < 11) || (count > 256))
311 goto out;
312
313 err = -ENOMEM;
314 memsize = sizeof(Node) + count + 8;
315 e = (Node *) kmalloc(memsize, GFP_USER);
316 if (!e)
317 goto out;
318
319 p = buf = (char *)e + sizeof(Node);
320
321 memset(e, 0, sizeof(Node));
322 if (copy_from_user(buf, buffer, count))
323 goto Efault;
324
325 del = *p++; /* delimeter */
326
327 memset(buf+count, del, 8);
328
329 e->name = p;
330 p = strchr(p, del);
331 if (!p)
332 goto Einval;
333 *p++ = '\0';
334 if (!e->name[0] ||
335 !strcmp(e->name, ".") ||
336 !strcmp(e->name, "..") ||
337 strchr(e->name, '/'))
338 goto Einval;
339 switch (*p++) {
340 case 'E': e->flags = 1<<Enabled; break;
341 case 'M': e->flags = (1<<Enabled) | (1<<Magic); break;
342 default: goto Einval;
343 }
344 if (*p++ != del)
345 goto Einval;
346 if (test_bit(Magic, &e->flags)) {
347 char *s = strchr(p, del);
348 if (!s)
349 goto Einval;
350 *s++ = '\0';
351 e->offset = simple_strtoul(p, &p, 10);
352 if (*p++)
353 goto Einval;
354 e->magic = p;
355 p = scanarg(p, del);
356 if (!p)
357 goto Einval;
358 p[-1] = '\0';
359 if (!e->magic[0])
360 goto Einval;
361 e->mask = p;
362 p = scanarg(p, del);
363 if (!p)
364 goto Einval;
365 p[-1] = '\0';
366 if (!e->mask[0])
367 e->mask = NULL;
368 e->size = unquote(e->magic);
369 if (e->mask && unquote(e->mask) != e->size)
370 goto Einval;
371 if (e->size + e->offset > BINPRM_BUF_SIZE)
372 goto Einval;
373 } else {
374 p = strchr(p, del);
375 if (!p)
376 goto Einval;
377 *p++ = '\0';
378 e->magic = p;
379 p = strchr(p, del);
380 if (!p)
381 goto Einval;
382 *p++ = '\0';
383 if (!e->magic[0] || strchr(e->magic, '/'))
384 goto Einval;
385 p = strchr(p, del);
386 if (!p)
387 goto Einval;
388 *p++ = '\0';
389 }
390 e->interpreter = p;
391 p = strchr(p, del);
392 if (!p)
393 goto Einval;
394 *p++ = '\0';
395 if (!e->interpreter[0])
396 goto Einval;
397
398
399 p = check_special_flags (p, e);
400
401 if (*p == '\n')
402 p++;
403 if (p != buf + count)
404 goto Einval;
405 return e;
406
407out:
408 return ERR_PTR(err);
409
410Efault:
411 kfree(e);
412 return ERR_PTR(-EFAULT);
413Einval:
414 kfree(e);
415 return ERR_PTR(-EINVAL);
416}
417
418/*
419 * Set status of entry/binfmt_misc:
420 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
421 */
422static int parse_command(const char __user *buffer, size_t count)
423{
424 char s[4];
425
426 if (!count)
427 return 0;
428 if (count > 3)
429 return -EINVAL;
430 if (copy_from_user(s, buffer, count))
431 return -EFAULT;
432 if (s[count-1] == '\n')
433 count--;
434 if (count == 1 && s[0] == '0')
435 return 1;
436 if (count == 1 && s[0] == '1')
437 return 2;
438 if (count == 2 && s[0] == '-' && s[1] == '1')
439 return 3;
440 return -EINVAL;
441}
442
443/* generic stuff */
444
445static void entry_status(Node *e, char *page)
446{
447 char *dp;
448 char *status = "disabled";
449 const char * flags = "flags: ";
450
451 if (test_bit(Enabled, &e->flags))
452 status = "enabled";
453
454 if (!VERBOSE_STATUS) {
455 sprintf(page, "%s\n", status);
456 return;
457 }
458
459 sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter);
460 dp = page + strlen(page);
461
462 /* print the special flags */
463 sprintf (dp, "%s", flags);
464 dp += strlen (flags);
465 if (e->flags & MISC_FMT_PRESERVE_ARGV0) {
466 *dp ++ = 'P';
467 }
468 if (e->flags & MISC_FMT_OPEN_BINARY) {
469 *dp ++ = 'O';
470 }
471 if (e->flags & MISC_FMT_CREDENTIALS) {
472 *dp ++ = 'C';
473 }
474 *dp ++ = '\n';
475
476
477 if (!test_bit(Magic, &e->flags)) {
478 sprintf(dp, "extension .%s\n", e->magic);
479 } else {
480 int i;
481
482 sprintf(dp, "offset %i\nmagic ", e->offset);
483 dp = page + strlen(page);
484 for (i = 0; i < e->size; i++) {
485 sprintf(dp, "%02x", 0xff & (int) (e->magic[i]));
486 dp += 2;
487 }
488 if (e->mask) {
489 sprintf(dp, "\nmask ");
490 dp += 6;
491 for (i = 0; i < e->size; i++) {
492 sprintf(dp, "%02x", 0xff & (int) (e->mask[i]));
493 dp += 2;
494 }
495 }
496 *dp++ = '\n';
497 *dp = '\0';
498 }
499}
500
501static struct inode *bm_get_inode(struct super_block *sb, int mode)
502{
503 struct inode * inode = new_inode(sb);
504
505 if (inode) {
506 inode->i_mode = mode;
507 inode->i_uid = 0;
508 inode->i_gid = 0;
509 inode->i_blksize = PAGE_CACHE_SIZE;
510 inode->i_blocks = 0;
511 inode->i_atime = inode->i_mtime = inode->i_ctime =
512 current_fs_time(inode->i_sb);
513 }
514 return inode;
515}
516
517static void bm_clear_inode(struct inode *inode)
518{
519 kfree(inode->u.generic_ip);
520}
521
522static void kill_node(Node *e)
523{
524 struct dentry *dentry;
525
526 write_lock(&entries_lock);
527 dentry = e->dentry;
528 if (dentry) {
529 list_del_init(&e->list);
530 e->dentry = NULL;
531 }
532 write_unlock(&entries_lock);
533
534 if (dentry) {
535 dentry->d_inode->i_nlink--;
536 d_drop(dentry);
537 dput(dentry);
538 simple_release_fs(&bm_mnt, &entry_count);
539 }
540}
541
542/* /<entry> */
543
544static ssize_t
545bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
546{
547 Node *e = file->f_dentry->d_inode->u.generic_ip;
548 loff_t pos = *ppos;
549 ssize_t res;
550 char *page;
551 int len;
552
553 if (!(page = (char*) __get_free_page(GFP_KERNEL)))
554 return -ENOMEM;
555
556 entry_status(e, page);
557 len = strlen(page);
558
559 res = -EINVAL;
560 if (pos < 0)
561 goto out;
562 res = 0;
563 if (pos >= len)
564 goto out;
565 if (len < pos + nbytes)
566 nbytes = len - pos;
567 res = -EFAULT;
568 if (copy_to_user(buf, page + pos, nbytes))
569 goto out;
570 *ppos = pos + nbytes;
571 res = nbytes;
572out:
573 free_page((unsigned long) page);
574 return res;
575}
576
577static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
578 size_t count, loff_t *ppos)
579{
580 struct dentry *root;
581 Node *e = file->f_dentry->d_inode->u.generic_ip;
582 int res = parse_command(buffer, count);
583
584 switch (res) {
585 case 1: clear_bit(Enabled, &e->flags);
586 break;
587 case 2: set_bit(Enabled, &e->flags);
588 break;
589 case 3: root = dget(file->f_vfsmnt->mnt_sb->s_root);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800590 mutex_lock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
592 kill_node(e);
593
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800594 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 dput(root);
596 break;
597 default: return res;
598 }
599 return count;
600}
601
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800602static const struct file_operations bm_entry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 .read = bm_entry_read,
604 .write = bm_entry_write,
605};
606
607/* /register */
608
609static ssize_t bm_register_write(struct file *file, const char __user *buffer,
610 size_t count, loff_t *ppos)
611{
612 Node *e;
613 struct inode *inode;
614 struct dentry *root, *dentry;
615 struct super_block *sb = file->f_vfsmnt->mnt_sb;
616 int err = 0;
617
618 e = create_entry(buffer, count);
619
620 if (IS_ERR(e))
621 return PTR_ERR(e);
622
623 root = dget(sb->s_root);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800624 mutex_lock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 dentry = lookup_one_len(e->name, root, strlen(e->name));
626 err = PTR_ERR(dentry);
627 if (IS_ERR(dentry))
628 goto out;
629
630 err = -EEXIST;
631 if (dentry->d_inode)
632 goto out2;
633
634 inode = bm_get_inode(sb, S_IFREG | 0644);
635
636 err = -ENOMEM;
637 if (!inode)
638 goto out2;
639
640 err = simple_pin_fs("binfmt_misc", &bm_mnt, &entry_count);
641 if (err) {
642 iput(inode);
643 inode = NULL;
644 goto out2;
645 }
646
647 e->dentry = dget(dentry);
648 inode->u.generic_ip = e;
649 inode->i_fop = &bm_entry_operations;
650
651 d_instantiate(dentry, inode);
652 write_lock(&entries_lock);
653 list_add(&e->list, &entries);
654 write_unlock(&entries_lock);
655
656 err = 0;
657out2:
658 dput(dentry);
659out:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800660 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 dput(root);
662
663 if (err) {
664 kfree(e);
665 return -EINVAL;
666 }
667 return count;
668}
669
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800670static const struct file_operations bm_register_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 .write = bm_register_write,
672};
673
674/* /status */
675
676static ssize_t
677bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
678{
679 char *s = enabled ? "enabled" : "disabled";
680 int len = strlen(s);
681 loff_t pos = *ppos;
682
683 if (pos < 0)
684 return -EINVAL;
685 if (pos >= len)
686 return 0;
687 if (len < pos + nbytes)
688 nbytes = len - pos;
689 if (copy_to_user(buf, s + pos, nbytes))
690 return -EFAULT;
691 *ppos = pos + nbytes;
692 return nbytes;
693}
694
695static ssize_t bm_status_write(struct file * file, const char __user * buffer,
696 size_t count, loff_t *ppos)
697{
698 int res = parse_command(buffer, count);
699 struct dentry *root;
700
701 switch (res) {
702 case 1: enabled = 0; break;
703 case 2: enabled = 1; break;
704 case 3: root = dget(file->f_vfsmnt->mnt_sb->s_root);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800705 mutex_lock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706
707 while (!list_empty(&entries))
708 kill_node(list_entry(entries.next, Node, list));
709
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800710 mutex_unlock(&root->d_inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 dput(root);
712 default: return res;
713 }
714 return count;
715}
716
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800717static const struct file_operations bm_status_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 .read = bm_status_read,
719 .write = bm_status_write,
720};
721
722/* Superblock handling */
723
724static struct super_operations s_ops = {
725 .statfs = simple_statfs,
726 .clear_inode = bm_clear_inode,
727};
728
729static int bm_fill_super(struct super_block * sb, void * data, int silent)
730{
731 static struct tree_descr bm_files[] = {
732 [1] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
733 [2] = {"register", &bm_register_operations, S_IWUSR},
734 /* last one */ {""}
735 };
736 int err = simple_fill_super(sb, 0x42494e4d, bm_files);
737 if (!err)
738 sb->s_op = &s_ops;
739 return err;
740}
741
David Howells454e2392006-06-23 02:02:57 -0700742static int bm_get_sb(struct file_system_type *fs_type,
743 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744{
David Howells454e2392006-06-23 02:02:57 -0700745 return get_sb_single(fs_type, flags, data, bm_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746}
747
748static struct linux_binfmt misc_format = {
749 .module = THIS_MODULE,
750 .load_binary = load_misc_binary,
751};
752
753static struct file_system_type bm_fs_type = {
754 .owner = THIS_MODULE,
755 .name = "binfmt_misc",
756 .get_sb = bm_get_sb,
757 .kill_sb = kill_litter_super,
758};
759
760static int __init init_misc_binfmt(void)
761{
762 int err = register_filesystem(&bm_fs_type);
763 if (!err) {
764 err = register_binfmt(&misc_format);
765 if (err)
766 unregister_filesystem(&bm_fs_type);
767 }
768 return err;
769}
770
771static void __exit exit_misc_binfmt(void)
772{
773 unregister_binfmt(&misc_format);
774 unregister_filesystem(&bm_fs_type);
775}
776
777core_initcall(init_misc_binfmt);
778module_exit(exit_misc_binfmt);
779MODULE_LICENSE("GPL");