mm-only debug patch...
[mmotm.git] / fs / binfmt_misc.c
blobc4e83537ead77501f03d7fcb3a748727f2624d5e
1 /*
2 * binfmt_misc.c
4 * Copyright (C) 1997 Richard Günther
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.
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.
19 #include <linux/module.h>
20 #include <linux/init.h>
21 #include <linux/sched.h>
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 #include <linux/fs.h>
32 #include <asm/uaccess.h>
34 enum {
35 VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
38 static LIST_HEAD(entries);
39 static int enabled = 1;
41 enum {Enabled, Magic};
42 #define MISC_FMT_PRESERVE_ARGV0 (1<<31)
43 #define MISC_FMT_OPEN_BINARY (1<<30)
44 #define MISC_FMT_CREDENTIALS (1<<29)
46 typedef struct {
47 struct list_head list;
48 unsigned long flags; /* type, status, etc. */
49 int offset; /* offset of magic */
50 int size; /* size of magic/mask */
51 char *magic; /* magic or filename extension */
52 char *mask; /* mask, NULL for exact match */
53 char *interpreter; /* filename of interpreter */
54 char *name;
55 struct dentry *dentry;
56 } Node;
58 static DEFINE_RWLOCK(entries_lock);
59 static struct file_system_type bm_fs_type;
60 static struct vfsmount *bm_mnt;
61 static int entry_count;
63 /*
64 * Check if we support the binfmt
65 * if we do, return the node, else NULL
66 * locking is done in load_misc_binary
68 static Node *check_file(struct linux_binprm *bprm)
70 char *p = strrchr(bprm->interp, '.');
71 struct list_head *l;
73 list_for_each(l, &entries) {
74 Node *e = list_entry(l, Node, list);
75 char *s;
76 int j;
78 if (!test_bit(Enabled, &e->flags))
79 continue;
81 if (!test_bit(Magic, &e->flags)) {
82 if (p && !strcmp(e->magic, p + 1))
83 return e;
84 continue;
87 s = bprm->buf + e->offset;
88 if (e->mask) {
89 for (j = 0; j < e->size; j++)
90 if ((*s++ ^ e->magic[j]) & e->mask[j])
91 break;
92 } else {
93 for (j = 0; j < e->size; j++)
94 if ((*s++ ^ e->magic[j]))
95 break;
97 if (j == e->size)
98 return e;
100 return NULL;
104 * the loader itself
106 static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)
108 Node *fmt;
109 struct file * interp_file = NULL;
110 char iname[BINPRM_BUF_SIZE];
111 char *iname_addr = iname;
112 int retval;
113 int fd_binary = -1;
115 retval = -ENOEXEC;
116 if (!enabled)
117 goto _ret;
119 retval = -ENOEXEC;
120 if (bprm->recursion_depth > BINPRM_MAX_RECURSION)
121 goto _ret;
123 /* to keep locking time low, we copy the interpreter string */
124 read_lock(&entries_lock);
125 fmt = check_file(bprm);
126 if (fmt)
127 strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
128 read_unlock(&entries_lock);
129 if (!fmt)
130 goto _ret;
132 if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
133 retval = remove_arg_zero(bprm);
134 if (retval)
135 goto _ret;
138 if (fmt->flags & MISC_FMT_OPEN_BINARY) {
140 /* if the binary should be opened on behalf of the
141 * interpreter than keep it open and assign descriptor
142 * to it */
143 fd_binary = get_unused_fd();
144 if (fd_binary < 0) {
145 retval = fd_binary;
146 goto _ret;
148 fd_install(fd_binary, bprm->file);
150 /* if the binary is not readable than enforce mm->dumpable=0
151 regardless of the interpreter's permissions */
152 if (file_permission(bprm->file, MAY_READ))
153 bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
155 allow_write_access(bprm->file);
156 bprm->file = NULL;
158 /* mark the bprm that fd should be passed to interp */
159 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
160 bprm->interp_data = fd_binary;
162 } else {
163 allow_write_access(bprm->file);
164 fput(bprm->file);
165 bprm->file = NULL;
167 /* make argv[1] be the path to the binary */
168 retval = copy_strings_kernel (1, &bprm->interp, bprm);
169 if (retval < 0)
170 goto _error;
171 bprm->argc++;
173 /* add the interp as argv[0] */
174 retval = copy_strings_kernel (1, &iname_addr, bprm);
175 if (retval < 0)
176 goto _error;
177 bprm->argc ++;
179 bprm->interp = iname; /* for binfmt_script */
181 interp_file = open_exec (iname);
182 retval = PTR_ERR (interp_file);
183 if (IS_ERR (interp_file))
184 goto _error;
186 bprm->file = interp_file;
187 if (fmt->flags & MISC_FMT_CREDENTIALS) {
189 * No need to call prepare_binprm(), it's already been
190 * done. bprm->buf is stale, update from interp_file.
192 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
193 retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
194 } else
195 retval = prepare_binprm (bprm);
197 if (retval < 0)
198 goto _error;
200 bprm->recursion_depth++;
202 retval = search_binary_handler (bprm, regs);
203 if (retval < 0)
204 goto _error;
206 _ret:
207 return retval;
208 _error:
209 if (fd_binary > 0)
210 sys_close(fd_binary);
211 bprm->interp_flags = 0;
212 bprm->interp_data = 0;
213 goto _ret;
216 /* Command parsers */
219 * parses and copies one argument enclosed in del from *sp to *dp,
220 * recognising the \x special.
221 * returns pointer to the copied argument or NULL in case of an
222 * error (and sets err) or null argument length.
224 static char *scanarg(char *s, char del)
226 char c;
228 while ((c = *s++) != del) {
229 if (c == '\\' && *s == 'x') {
230 s++;
231 if (!isxdigit(*s++))
232 return NULL;
233 if (!isxdigit(*s++))
234 return NULL;
237 return s;
240 static int unquote(char *from)
242 char c = 0, *s = from, *p = from;
244 while ((c = *s++) != '\0') {
245 if (c == '\\' && *s == 'x') {
246 s++;
247 c = toupper(*s++);
248 *p = (c - (isdigit(c) ? '0' : 'A' - 10)) << 4;
249 c = toupper(*s++);
250 *p++ |= c - (isdigit(c) ? '0' : 'A' - 10);
251 continue;
253 *p++ = c;
255 return p - from;
258 static char * check_special_flags (char * sfs, Node * e)
260 char * p = sfs;
261 int cont = 1;
263 /* special flags */
264 while (cont) {
265 switch (*p) {
266 case 'P':
267 p++;
268 e->flags |= MISC_FMT_PRESERVE_ARGV0;
269 break;
270 case 'O':
271 p++;
272 e->flags |= MISC_FMT_OPEN_BINARY;
273 break;
274 case 'C':
275 p++;
276 /* this flags also implies the
277 open-binary flag */
278 e->flags |= (MISC_FMT_CREDENTIALS |
279 MISC_FMT_OPEN_BINARY);
280 break;
281 default:
282 cont = 0;
286 return p;
289 * This registers a new binary format, it recognises the syntax
290 * ':name:type:offset:magic:mask:interpreter:flags'
291 * where the ':' is the IFS, that can be chosen with the first char
293 static Node *create_entry(const char __user *buffer, size_t count)
295 Node *e;
296 int memsize, err;
297 char *buf, *p;
298 char del;
300 /* some sanity checks */
301 err = -EINVAL;
302 if ((count < 11) || (count > 256))
303 goto out;
305 err = -ENOMEM;
306 memsize = sizeof(Node) + count + 8;
307 e = kmalloc(memsize, GFP_USER);
308 if (!e)
309 goto out;
311 p = buf = (char *)e + sizeof(Node);
313 memset(e, 0, sizeof(Node));
314 if (copy_from_user(buf, buffer, count))
315 goto Efault;
317 del = *p++; /* delimeter */
319 memset(buf+count, del, 8);
321 e->name = p;
322 p = strchr(p, del);
323 if (!p)
324 goto Einval;
325 *p++ = '\0';
326 if (!e->name[0] ||
327 !strcmp(e->name, ".") ||
328 !strcmp(e->name, "..") ||
329 strchr(e->name, '/'))
330 goto Einval;
331 switch (*p++) {
332 case 'E': e->flags = 1<<Enabled; break;
333 case 'M': e->flags = (1<<Enabled) | (1<<Magic); break;
334 default: goto Einval;
336 if (*p++ != del)
337 goto Einval;
338 if (test_bit(Magic, &e->flags)) {
339 char *s = strchr(p, del);
340 if (!s)
341 goto Einval;
342 *s++ = '\0';
343 e->offset = simple_strtoul(p, &p, 10);
344 if (*p++)
345 goto Einval;
346 e->magic = p;
347 p = scanarg(p, del);
348 if (!p)
349 goto Einval;
350 p[-1] = '\0';
351 if (!e->magic[0])
352 goto Einval;
353 e->mask = p;
354 p = scanarg(p, del);
355 if (!p)
356 goto Einval;
357 p[-1] = '\0';
358 if (!e->mask[0])
359 e->mask = NULL;
360 e->size = unquote(e->magic);
361 if (e->mask && unquote(e->mask) != e->size)
362 goto Einval;
363 if (e->size + e->offset > BINPRM_BUF_SIZE)
364 goto Einval;
365 } else {
366 p = strchr(p, del);
367 if (!p)
368 goto Einval;
369 *p++ = '\0';
370 e->magic = p;
371 p = strchr(p, del);
372 if (!p)
373 goto Einval;
374 *p++ = '\0';
375 if (!e->magic[0] || strchr(e->magic, '/'))
376 goto Einval;
377 p = strchr(p, del);
378 if (!p)
379 goto Einval;
380 *p++ = '\0';
382 e->interpreter = p;
383 p = strchr(p, del);
384 if (!p)
385 goto Einval;
386 *p++ = '\0';
387 if (!e->interpreter[0])
388 goto Einval;
391 p = check_special_flags (p, e);
393 if (*p == '\n')
394 p++;
395 if (p != buf + count)
396 goto Einval;
397 return e;
399 out:
400 return ERR_PTR(err);
402 Efault:
403 kfree(e);
404 return ERR_PTR(-EFAULT);
405 Einval:
406 kfree(e);
407 return ERR_PTR(-EINVAL);
411 * Set status of entry/binfmt_misc:
412 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
414 static int parse_command(const char __user *buffer, size_t count)
416 char s[4];
418 if (!count)
419 return 0;
420 if (count > 3)
421 return -EINVAL;
422 if (copy_from_user(s, buffer, count))
423 return -EFAULT;
424 if (s[count-1] == '\n')
425 count--;
426 if (count == 1 && s[0] == '0')
427 return 1;
428 if (count == 1 && s[0] == '1')
429 return 2;
430 if (count == 2 && s[0] == '-' && s[1] == '1')
431 return 3;
432 return -EINVAL;
435 /* generic stuff */
437 static void entry_status(Node *e, char *page)
439 char *dp;
440 char *status = "disabled";
441 const char * flags = "flags: ";
443 if (test_bit(Enabled, &e->flags))
444 status = "enabled";
446 if (!VERBOSE_STATUS) {
447 sprintf(page, "%s\n", status);
448 return;
451 sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter);
452 dp = page + strlen(page);
454 /* print the special flags */
455 sprintf (dp, "%s", flags);
456 dp += strlen (flags);
457 if (e->flags & MISC_FMT_PRESERVE_ARGV0) {
458 *dp ++ = 'P';
460 if (e->flags & MISC_FMT_OPEN_BINARY) {
461 *dp ++ = 'O';
463 if (e->flags & MISC_FMT_CREDENTIALS) {
464 *dp ++ = 'C';
466 *dp ++ = '\n';
469 if (!test_bit(Magic, &e->flags)) {
470 sprintf(dp, "extension .%s\n", e->magic);
471 } else {
472 int i;
474 sprintf(dp, "offset %i\nmagic ", e->offset);
475 dp = page + strlen(page);
476 for (i = 0; i < e->size; i++) {
477 sprintf(dp, "%02x", 0xff & (int) (e->magic[i]));
478 dp += 2;
480 if (e->mask) {
481 sprintf(dp, "\nmask ");
482 dp += 6;
483 for (i = 0; i < e->size; i++) {
484 sprintf(dp, "%02x", 0xff & (int) (e->mask[i]));
485 dp += 2;
488 *dp++ = '\n';
489 *dp = '\0';
493 static struct inode *bm_get_inode(struct super_block *sb, int mode)
495 struct inode * inode = new_inode(sb);
497 if (inode) {
498 inode->i_mode = mode;
499 inode->i_atime = inode->i_mtime = inode->i_ctime =
500 current_fs_time(inode->i_sb);
502 return inode;
505 static void bm_clear_inode(struct inode *inode)
507 kfree(inode->i_private);
510 static void kill_node(Node *e)
512 struct dentry *dentry;
514 write_lock(&entries_lock);
515 dentry = e->dentry;
516 if (dentry) {
517 list_del_init(&e->list);
518 e->dentry = NULL;
520 write_unlock(&entries_lock);
522 if (dentry) {
523 dentry->d_inode->i_nlink--;
524 d_drop(dentry);
525 dput(dentry);
526 simple_release_fs(&bm_mnt, &entry_count);
530 /* /<entry> */
532 static ssize_t
533 bm_entry_read(struct file * file, char __user * buf, size_t nbytes, loff_t *ppos)
535 Node *e = file->f_path.dentry->d_inode->i_private;
536 ssize_t res;
537 char *page;
539 if (!(page = (char*) __get_free_page(GFP_KERNEL)))
540 return -ENOMEM;
542 entry_status(e, page);
544 res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
546 free_page((unsigned long) page);
547 return res;
550 static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
551 size_t count, loff_t *ppos)
553 struct dentry *root;
554 Node *e = file->f_path.dentry->d_inode->i_private;
555 int res = parse_command(buffer, count);
557 switch (res) {
558 case 1: clear_bit(Enabled, &e->flags);
559 break;
560 case 2: set_bit(Enabled, &e->flags);
561 break;
562 case 3: root = dget(file->f_path.mnt->mnt_sb->s_root);
563 mutex_lock(&root->d_inode->i_mutex);
565 kill_node(e);
567 mutex_unlock(&root->d_inode->i_mutex);
568 dput(root);
569 break;
570 default: return res;
572 return count;
575 static const struct file_operations bm_entry_operations = {
576 .read = bm_entry_read,
577 .write = bm_entry_write,
580 /* /register */
582 static ssize_t bm_register_write(struct file *file, const char __user *buffer,
583 size_t count, loff_t *ppos)
585 Node *e;
586 struct inode *inode;
587 struct dentry *root, *dentry;
588 struct super_block *sb = file->f_path.mnt->mnt_sb;
589 int err = 0;
591 e = create_entry(buffer, count);
593 if (IS_ERR(e))
594 return PTR_ERR(e);
596 root = dget(sb->s_root);
597 mutex_lock(&root->d_inode->i_mutex);
598 dentry = lookup_one_len(e->name, root, strlen(e->name));
599 err = PTR_ERR(dentry);
600 if (IS_ERR(dentry))
601 goto out;
603 err = -EEXIST;
604 if (dentry->d_inode)
605 goto out2;
607 inode = bm_get_inode(sb, S_IFREG | 0644);
609 err = -ENOMEM;
610 if (!inode)
611 goto out2;
613 err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
614 if (err) {
615 iput(inode);
616 inode = NULL;
617 goto out2;
620 e->dentry = dget(dentry);
621 inode->i_private = e;
622 inode->i_fop = &bm_entry_operations;
624 d_instantiate(dentry, inode);
625 write_lock(&entries_lock);
626 list_add(&e->list, &entries);
627 write_unlock(&entries_lock);
629 err = 0;
630 out2:
631 dput(dentry);
632 out:
633 mutex_unlock(&root->d_inode->i_mutex);
634 dput(root);
636 if (err) {
637 kfree(e);
638 return -EINVAL;
640 return count;
643 static const struct file_operations bm_register_operations = {
644 .write = bm_register_write,
647 /* /status */
649 static ssize_t
650 bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
652 char *s = enabled ? "enabled\n" : "disabled\n";
654 return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
657 static ssize_t bm_status_write(struct file * file, const char __user * buffer,
658 size_t count, loff_t *ppos)
660 int res = parse_command(buffer, count);
661 struct dentry *root;
663 switch (res) {
664 case 1: enabled = 0; break;
665 case 2: enabled = 1; break;
666 case 3: root = dget(file->f_path.mnt->mnt_sb->s_root);
667 mutex_lock(&root->d_inode->i_mutex);
669 while (!list_empty(&entries))
670 kill_node(list_entry(entries.next, Node, list));
672 mutex_unlock(&root->d_inode->i_mutex);
673 dput(root);
674 default: return res;
676 return count;
679 static const struct file_operations bm_status_operations = {
680 .read = bm_status_read,
681 .write = bm_status_write,
684 /* Superblock handling */
686 static const struct super_operations s_ops = {
687 .statfs = simple_statfs,
688 .clear_inode = bm_clear_inode,
691 static int bm_fill_super(struct super_block * sb, void * data, int silent)
693 static struct tree_descr bm_files[] = {
694 [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
695 [3] = {"register", &bm_register_operations, S_IWUSR},
696 /* last one */ {""}
698 int err = simple_fill_super(sb, 0x42494e4d, bm_files);
699 if (!err)
700 sb->s_op = &s_ops;
701 return err;
704 static int bm_get_sb(struct file_system_type *fs_type,
705 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
707 return get_sb_single(fs_type, flags, data, bm_fill_super, mnt);
710 static struct linux_binfmt misc_format = {
711 .module = THIS_MODULE,
712 .load_binary = load_misc_binary,
715 static struct file_system_type bm_fs_type = {
716 .owner = THIS_MODULE,
717 .name = "binfmt_misc",
718 .get_sb = bm_get_sb,
719 .kill_sb = kill_litter_super,
722 static int __init init_misc_binfmt(void)
724 int err = register_filesystem(&bm_fs_type);
725 if (!err) {
726 err = register_binfmt(&misc_format);
727 if (err)
728 unregister_filesystem(&bm_fs_type);
730 return err;
733 static void __exit exit_misc_binfmt(void)
735 unregister_binfmt(&misc_format);
736 unregister_filesystem(&bm_fs_type);
739 core_initcall(init_misc_binfmt);
740 module_exit(exit_misc_binfmt);
741 MODULE_LICENSE("GPL");