Commit | Line | Data |
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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 | 2 | /* |
e6084d4a | 3 | * binfmt_misc.c |
1da177e4 | 4 | * |
e6084d4a | 5 | * Copyright (C) 1997 Richard Günther |
1da177e4 | 6 | * |
e6084d4a | 7 | * binfmt_misc detects binaries via a magic or filename extension and invokes |
34962fb8 | 8 | * a specified wrapper. See Documentation/admin-guide/binfmt-misc.rst for more details. |
1da177e4 LT |
9 | */ |
10 | ||
6b899c4e MF |
11 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
12 | ||
6ceafb88 | 13 | #include <linux/kernel.h> |
1da177e4 LT |
14 | #include <linux/module.h> |
15 | #include <linux/init.h> | |
589ee628 | 16 | #include <linux/sched/mm.h> |
b502bd11 | 17 | #include <linux/magic.h> |
1da177e4 LT |
18 | #include <linux/binfmts.h> |
19 | #include <linux/slab.h> | |
20 | #include <linux/ctype.h> | |
8d82e180 | 21 | #include <linux/string_helpers.h> |
1da177e4 LT |
22 | #include <linux/file.h> |
23 | #include <linux/pagemap.h> | |
24 | #include <linux/namei.h> | |
25 | #include <linux/mount.h> | |
bc99a664 | 26 | #include <linux/fs_context.h> |
1da177e4 | 27 | #include <linux/syscalls.h> |
6e2c10a1 | 28 | #include <linux/fs.h> |
6b899c4e | 29 | #include <linux/uaccess.h> |
1da177e4 | 30 | |
948b701a JB |
31 | #include "internal.h" |
32 | ||
6b899c4e MF |
33 | #ifdef DEBUG |
34 | # define USE_DEBUG 1 | |
35 | #else | |
36 | # define USE_DEBUG 0 | |
37 | #endif | |
1da177e4 LT |
38 | |
39 | enum { | |
40 | VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */ | |
41 | }; | |
42 | ||
43 | static LIST_HEAD(entries); | |
44 | static int enabled = 1; | |
45 | ||
46 | enum {Enabled, Magic}; | |
6a46bf55 LS |
47 | #define MISC_FMT_PRESERVE_ARGV0 (1UL << 31) |
48 | #define MISC_FMT_OPEN_BINARY (1UL << 30) | |
49 | #define MISC_FMT_CREDENTIALS (1UL << 29) | |
50 | #define MISC_FMT_OPEN_FILE (1UL << 28) | |
1da177e4 LT |
51 | |
52 | typedef struct { | |
53 | struct list_head list; | |
54 | unsigned long flags; /* type, status, etc. */ | |
55 | int offset; /* offset of magic */ | |
56 | int size; /* size of magic/mask */ | |
57 | char *magic; /* magic or filename extension */ | |
58 | char *mask; /* mask, NULL for exact match */ | |
50097f74 | 59 | const char *interpreter; /* filename of interpreter */ |
1da177e4 LT |
60 | char *name; |
61 | struct dentry *dentry; | |
948b701a | 62 | struct file *interp_file; |
1c5976ef | 63 | refcount_t users; /* sync removal with load_misc_binary() */ |
1da177e4 LT |
64 | } Node; |
65 | ||
66 | static DEFINE_RWLOCK(entries_lock); | |
1f5ce9e9 | 67 | static struct file_system_type bm_fs_type; |
1da177e4 | 68 | |
bbaecc08 MF |
69 | /* |
70 | * Max length of the register string. Determined by: | |
71 | * - 7 delimiters | |
72 | * - name: ~50 bytes | |
73 | * - type: 1 byte | |
74 | * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE) | |
75 | * - magic: 128 bytes (512 in escaped form) | |
76 | * - mask: 128 bytes (512 in escaped form) | |
77 | * - interp: ~50 bytes | |
78 | * - flags: 5 bytes | |
79 | * Round that up a bit, and then back off to hold the internal data | |
80 | * (like struct Node). | |
81 | */ | |
82 | #define MAX_REGISTER_LENGTH 1920 | |
83 | ||
1c5976ef CB |
84 | /** |
85 | * search_binfmt_handler - search for a binary handler for @bprm | |
86 | * @misc: handle to binfmt_misc instance | |
87 | * @bprm: binary for which we are looking for a handler | |
88 | * | |
89 | * Search for a binary type handler for @bprm in the list of registered binary | |
90 | * type handlers. | |
91 | * | |
92 | * Return: binary type list entry on success, NULL on failure | |
1da177e4 | 93 | */ |
1c5976ef | 94 | static Node *search_binfmt_handler(struct linux_binprm *bprm) |
1da177e4 LT |
95 | { |
96 | char *p = strrchr(bprm->interp, '.'); | |
1c5976ef | 97 | Node *e; |
1da177e4 | 98 | |
6b899c4e | 99 | /* Walk all the registered handlers. */ |
1c5976ef | 100 | list_for_each_entry(e, &entries, list) { |
1da177e4 LT |
101 | char *s; |
102 | int j; | |
103 | ||
6b899c4e | 104 | /* Make sure this one is currently enabled. */ |
1da177e4 LT |
105 | if (!test_bit(Enabled, &e->flags)) |
106 | continue; | |
107 | ||
6b899c4e | 108 | /* Do matching based on extension if applicable. */ |
1da177e4 LT |
109 | if (!test_bit(Magic, &e->flags)) { |
110 | if (p && !strcmp(e->magic, p + 1)) | |
111 | return e; | |
112 | continue; | |
113 | } | |
114 | ||
6b899c4e | 115 | /* Do matching based on magic & mask. */ |
1da177e4 LT |
116 | s = bprm->buf + e->offset; |
117 | if (e->mask) { | |
118 | for (j = 0; j < e->size; j++) | |
119 | if ((*s++ ^ e->magic[j]) & e->mask[j]) | |
120 | break; | |
121 | } else { | |
122 | for (j = 0; j < e->size; j++) | |
123 | if ((*s++ ^ e->magic[j])) | |
124 | break; | |
125 | } | |
126 | if (j == e->size) | |
127 | return e; | |
128 | } | |
1c5976ef | 129 | |
1da177e4 LT |
130 | return NULL; |
131 | } | |
132 | ||
1c5976ef CB |
133 | /** |
134 | * get_binfmt_handler - try to find a binary type handler | |
135 | * @misc: handle to binfmt_misc instance | |
136 | * @bprm: binary for which we are looking for a handler | |
137 | * | |
138 | * Try to find a binfmt handler for the binary type. If one is found take a | |
139 | * reference to protect against removal via bm_{entry,status}_write(). | |
140 | * | |
141 | * Return: binary type list entry on success, NULL on failure | |
142 | */ | |
143 | static Node *get_binfmt_handler(struct linux_binprm *bprm) | |
144 | { | |
145 | Node *e; | |
146 | ||
147 | read_lock(&entries_lock); | |
148 | e = search_binfmt_handler(bprm); | |
149 | if (e) | |
150 | refcount_inc(&e->users); | |
151 | read_unlock(&entries_lock); | |
152 | return e; | |
153 | } | |
154 | ||
155 | /** | |
156 | * put_binfmt_handler - put binary handler node | |
157 | * @e: node to put | |
158 | * | |
159 | * Free node syncing with load_misc_binary() and defer final free to | |
160 | * load_misc_binary() in case it is using the binary type handler we were | |
161 | * requested to remove. | |
162 | */ | |
163 | static void put_binfmt_handler(Node *e) | |
164 | { | |
165 | if (refcount_dec_and_test(&e->users)) { | |
166 | if (e->flags & MISC_FMT_OPEN_FILE) | |
167 | filp_close(e->interp_file, NULL); | |
168 | kfree(e); | |
169 | } | |
170 | } | |
171 | ||
1da177e4 LT |
172 | /* |
173 | * the loader itself | |
174 | */ | |
71613c3b | 175 | static int load_misc_binary(struct linux_binprm *bprm) |
1da177e4 LT |
176 | { |
177 | Node *fmt; | |
e6084d4a | 178 | struct file *interp_file = NULL; |
1da177e4 | 179 | int retval; |
1da177e4 LT |
180 | |
181 | retval = -ENOEXEC; | |
182 | if (!enabled) | |
43a4f261 | 183 | return retval; |
1da177e4 | 184 | |
1c5976ef | 185 | fmt = get_binfmt_handler(bprm); |
1da177e4 | 186 | if (!fmt) |
43a4f261 | 187 | return retval; |
1da177e4 | 188 | |
51f39a1f | 189 | /* Need to be able to load the file after exec */ |
43a4f261 | 190 | retval = -ENOENT; |
51f39a1f | 191 | if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) |
43a4f261 | 192 | goto ret; |
51f39a1f | 193 | |
2347961b LV |
194 | if (fmt->flags & MISC_FMT_PRESERVE_ARGV0) { |
195 | bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0; | |
196 | } else { | |
b6a2fea3 OW |
197 | retval = remove_arg_zero(bprm); |
198 | if (retval) | |
e6084d4a | 199 | goto ret; |
1da177e4 LT |
200 | } |
201 | ||
bc2bf338 | 202 | if (fmt->flags & MISC_FMT_OPEN_BINARY) |
b8a61c9e | 203 | bprm->have_execfd = 1; |
1da177e4 | 204 | |
1da177e4 | 205 | /* make argv[1] be the path to the binary */ |
986db2d1 | 206 | retval = copy_string_kernel(bprm->interp, bprm); |
1da177e4 | 207 | if (retval < 0) |
b8a61c9e | 208 | goto ret; |
1da177e4 LT |
209 | bprm->argc++; |
210 | ||
211 | /* add the interp as argv[0] */ | |
986db2d1 | 212 | retval = copy_string_kernel(fmt->interpreter, bprm); |
1da177e4 | 213 | if (retval < 0) |
b8a61c9e | 214 | goto ret; |
e6084d4a | 215 | bprm->argc++; |
1da177e4 | 216 | |
b66c5984 | 217 | /* Update interp in case binfmt_script needs it. */ |
50097f74 | 218 | retval = bprm_change_interp(fmt->interpreter, bprm); |
b66c5984 | 219 | if (retval < 0) |
b8a61c9e | 220 | goto ret; |
1da177e4 | 221 | |
eb23aa03 | 222 | if (fmt->flags & MISC_FMT_OPEN_FILE) { |
19f391eb | 223 | interp_file = file_clone_open(fmt->interp_file); |
948b701a JB |
224 | if (!IS_ERR(interp_file)) |
225 | deny_write_access(interp_file); | |
226 | } else { | |
50097f74 | 227 | interp_file = open_exec(fmt->interpreter); |
948b701a | 228 | } |
e6084d4a MF |
229 | retval = PTR_ERR(interp_file); |
230 | if (IS_ERR(interp_file)) | |
b8a61c9e | 231 | goto ret; |
1da177e4 | 232 | |
bc2bf338 | 233 | bprm->interpreter = interp_file; |
a16b3357 | 234 | if (fmt->flags & MISC_FMT_CREDENTIALS) |
56305aa9 | 235 | bprm->execfd_creds = 1; |
1da177e4 | 236 | |
bc2bf338 | 237 | retval = 0; |
e6084d4a | 238 | ret: |
1c5976ef CB |
239 | |
240 | /* | |
241 | * If we actually put the node here all concurrent calls to | |
242 | * load_misc_binary() will have finished. We also know | |
243 | * that for the refcount to be zero ->evict_inode() must have removed | |
244 | * the node to be deleted from the list. All that is left for us is to | |
245 | * close and free. | |
246 | */ | |
247 | put_binfmt_handler(fmt); | |
248 | ||
1da177e4 | 249 | return retval; |
1da177e4 LT |
250 | } |
251 | ||
252 | /* Command parsers */ | |
253 | ||
254 | /* | |
255 | * parses and copies one argument enclosed in del from *sp to *dp, | |
256 | * recognising the \x special. | |
257 | * returns pointer to the copied argument or NULL in case of an | |
258 | * error (and sets err) or null argument length. | |
259 | */ | |
260 | static char *scanarg(char *s, char del) | |
261 | { | |
262 | char c; | |
263 | ||
264 | while ((c = *s++) != del) { | |
265 | if (c == '\\' && *s == 'x') { | |
266 | s++; | |
267 | if (!isxdigit(*s++)) | |
268 | return NULL; | |
269 | if (!isxdigit(*s++)) | |
270 | return NULL; | |
271 | } | |
272 | } | |
7d65cf10 | 273 | s[-1] ='\0'; |
1da177e4 LT |
274 | return s; |
275 | } | |
276 | ||
e6084d4a | 277 | static char *check_special_flags(char *sfs, Node *e) |
1da177e4 | 278 | { |
e6084d4a | 279 | char *p = sfs; |
1da177e4 LT |
280 | int cont = 1; |
281 | ||
282 | /* special flags */ | |
283 | while (cont) { | |
284 | switch (*p) { | |
e6084d4a MF |
285 | case 'P': |
286 | pr_debug("register: flag: P (preserve argv0)\n"); | |
287 | p++; | |
288 | e->flags |= MISC_FMT_PRESERVE_ARGV0; | |
289 | break; | |
290 | case 'O': | |
291 | pr_debug("register: flag: O (open binary)\n"); | |
292 | p++; | |
293 | e->flags |= MISC_FMT_OPEN_BINARY; | |
294 | break; | |
295 | case 'C': | |
296 | pr_debug("register: flag: C (preserve creds)\n"); | |
297 | p++; | |
298 | /* this flags also implies the | |
299 | open-binary flag */ | |
300 | e->flags |= (MISC_FMT_CREDENTIALS | | |
301 | MISC_FMT_OPEN_BINARY); | |
302 | break; | |
948b701a JB |
303 | case 'F': |
304 | pr_debug("register: flag: F: open interpreter file now\n"); | |
305 | p++; | |
306 | e->flags |= MISC_FMT_OPEN_FILE; | |
307 | break; | |
e6084d4a MF |
308 | default: |
309 | cont = 0; | |
1da177e4 LT |
310 | } |
311 | } | |
312 | ||
313 | return p; | |
314 | } | |
e6084d4a | 315 | |
1da177e4 LT |
316 | /* |
317 | * This registers a new binary format, it recognises the syntax | |
318 | * ':name:type:offset:magic:mask:interpreter:flags' | |
319 | * where the ':' is the IFS, that can be chosen with the first char | |
320 | */ | |
321 | static Node *create_entry(const char __user *buffer, size_t count) | |
322 | { | |
323 | Node *e; | |
324 | int memsize, err; | |
325 | char *buf, *p; | |
326 | char del; | |
327 | ||
6b899c4e MF |
328 | pr_debug("register: received %zu bytes\n", count); |
329 | ||
1da177e4 LT |
330 | /* some sanity checks */ |
331 | err = -EINVAL; | |
bbaecc08 | 332 | if ((count < 11) || (count > MAX_REGISTER_LENGTH)) |
1da177e4 LT |
333 | goto out; |
334 | ||
335 | err = -ENOMEM; | |
336 | memsize = sizeof(Node) + count + 8; | |
f7e1ad1a | 337 | e = kmalloc(memsize, GFP_KERNEL); |
1da177e4 LT |
338 | if (!e) |
339 | goto out; | |
340 | ||
341 | p = buf = (char *)e + sizeof(Node); | |
342 | ||
343 | memset(e, 0, sizeof(Node)); | |
344 | if (copy_from_user(buf, buffer, count)) | |
e6084d4a | 345 | goto efault; |
1da177e4 LT |
346 | |
347 | del = *p++; /* delimeter */ | |
348 | ||
6b899c4e MF |
349 | pr_debug("register: delim: %#x {%c}\n", del, del); |
350 | ||
351 | /* Pad the buffer with the delim to simplify parsing below. */ | |
e6084d4a | 352 | memset(buf + count, del, 8); |
1da177e4 | 353 | |
6b899c4e | 354 | /* Parse the 'name' field. */ |
1da177e4 LT |
355 | e->name = p; |
356 | p = strchr(p, del); | |
357 | if (!p) | |
e6084d4a | 358 | goto einval; |
1da177e4 LT |
359 | *p++ = '\0'; |
360 | if (!e->name[0] || | |
361 | !strcmp(e->name, ".") || | |
362 | !strcmp(e->name, "..") || | |
363 | strchr(e->name, '/')) | |
e6084d4a | 364 | goto einval; |
6b899c4e MF |
365 | |
366 | pr_debug("register: name: {%s}\n", e->name); | |
367 | ||
368 | /* Parse the 'type' field. */ | |
1da177e4 | 369 | switch (*p++) { |
6b899c4e MF |
370 | case 'E': |
371 | pr_debug("register: type: E (extension)\n"); | |
372 | e->flags = 1 << Enabled; | |
373 | break; | |
374 | case 'M': | |
375 | pr_debug("register: type: M (magic)\n"); | |
376 | e->flags = (1 << Enabled) | (1 << Magic); | |
377 | break; | |
378 | default: | |
e6084d4a | 379 | goto einval; |
1da177e4 LT |
380 | } |
381 | if (*p++ != del) | |
e6084d4a | 382 | goto einval; |
6b899c4e | 383 | |
1da177e4 | 384 | if (test_bit(Magic, &e->flags)) { |
6b899c4e MF |
385 | /* Handle the 'M' (magic) format. */ |
386 | char *s; | |
387 | ||
388 | /* Parse the 'offset' field. */ | |
389 | s = strchr(p, del); | |
1da177e4 | 390 | if (!s) |
e6084d4a | 391 | goto einval; |
5cc41e09 TLSC |
392 | *s = '\0'; |
393 | if (p != s) { | |
394 | int r = kstrtoint(p, 10, &e->offset); | |
395 | if (r != 0 || e->offset < 0) | |
396 | goto einval; | |
397 | } | |
398 | p = s; | |
1da177e4 | 399 | if (*p++) |
e6084d4a | 400 | goto einval; |
6b899c4e MF |
401 | pr_debug("register: offset: %#x\n", e->offset); |
402 | ||
403 | /* Parse the 'magic' field. */ | |
1da177e4 LT |
404 | e->magic = p; |
405 | p = scanarg(p, del); | |
406 | if (!p) | |
e6084d4a | 407 | goto einval; |
7d65cf10 | 408 | if (!e->magic[0]) |
e6084d4a | 409 | goto einval; |
6b899c4e MF |
410 | if (USE_DEBUG) |
411 | print_hex_dump_bytes( | |
412 | KBUILD_MODNAME ": register: magic[raw]: ", | |
413 | DUMP_PREFIX_NONE, e->magic, p - e->magic); | |
414 | ||
415 | /* Parse the 'mask' field. */ | |
1da177e4 LT |
416 | e->mask = p; |
417 | p = scanarg(p, del); | |
418 | if (!p) | |
e6084d4a | 419 | goto einval; |
7d65cf10 | 420 | if (!e->mask[0]) { |
1da177e4 | 421 | e->mask = NULL; |
6b899c4e MF |
422 | pr_debug("register: mask[raw]: none\n"); |
423 | } else if (USE_DEBUG) | |
424 | print_hex_dump_bytes( | |
425 | KBUILD_MODNAME ": register: mask[raw]: ", | |
426 | DUMP_PREFIX_NONE, e->mask, p - e->mask); | |
427 | ||
428 | /* | |
429 | * Decode the magic & mask fields. | |
430 | * Note: while we might have accepted embedded NUL bytes from | |
431 | * above, the unescape helpers here will stop at the first one | |
432 | * it encounters. | |
433 | */ | |
8d82e180 AS |
434 | e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX); |
435 | if (e->mask && | |
436 | string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size) | |
e6084d4a | 437 | goto einval; |
5cc41e09 TLSC |
438 | if (e->size > BINPRM_BUF_SIZE || |
439 | BINPRM_BUF_SIZE - e->size < e->offset) | |
e6084d4a | 440 | goto einval; |
6b899c4e MF |
441 | pr_debug("register: magic/mask length: %i\n", e->size); |
442 | if (USE_DEBUG) { | |
443 | print_hex_dump_bytes( | |
444 | KBUILD_MODNAME ": register: magic[decoded]: ", | |
445 | DUMP_PREFIX_NONE, e->magic, e->size); | |
446 | ||
447 | if (e->mask) { | |
448 | int i; | |
f7e1ad1a | 449 | char *masked = kmalloc(e->size, GFP_KERNEL); |
6b899c4e MF |
450 | |
451 | print_hex_dump_bytes( | |
452 | KBUILD_MODNAME ": register: mask[decoded]: ", | |
453 | DUMP_PREFIX_NONE, e->mask, e->size); | |
454 | ||
455 | if (masked) { | |
456 | for (i = 0; i < e->size; ++i) | |
457 | masked[i] = e->magic[i] & e->mask[i]; | |
458 | print_hex_dump_bytes( | |
459 | KBUILD_MODNAME ": register: magic[masked]: ", | |
460 | DUMP_PREFIX_NONE, masked, e->size); | |
461 | ||
462 | kfree(masked); | |
463 | } | |
464 | } | |
465 | } | |
1da177e4 | 466 | } else { |
6b899c4e MF |
467 | /* Handle the 'E' (extension) format. */ |
468 | ||
469 | /* Skip the 'offset' field. */ | |
1da177e4 LT |
470 | p = strchr(p, del); |
471 | if (!p) | |
e6084d4a | 472 | goto einval; |
1da177e4 | 473 | *p++ = '\0'; |
6b899c4e MF |
474 | |
475 | /* Parse the 'magic' field. */ | |
1da177e4 LT |
476 | e->magic = p; |
477 | p = strchr(p, del); | |
478 | if (!p) | |
e6084d4a | 479 | goto einval; |
1da177e4 LT |
480 | *p++ = '\0'; |
481 | if (!e->magic[0] || strchr(e->magic, '/')) | |
e6084d4a | 482 | goto einval; |
6b899c4e MF |
483 | pr_debug("register: extension: {%s}\n", e->magic); |
484 | ||
485 | /* Skip the 'mask' field. */ | |
1da177e4 LT |
486 | p = strchr(p, del); |
487 | if (!p) | |
e6084d4a | 488 | goto einval; |
1da177e4 LT |
489 | *p++ = '\0'; |
490 | } | |
6b899c4e MF |
491 | |
492 | /* Parse the 'interpreter' field. */ | |
1da177e4 LT |
493 | e->interpreter = p; |
494 | p = strchr(p, del); | |
495 | if (!p) | |
e6084d4a | 496 | goto einval; |
1da177e4 LT |
497 | *p++ = '\0'; |
498 | if (!e->interpreter[0]) | |
e6084d4a | 499 | goto einval; |
6b899c4e | 500 | pr_debug("register: interpreter: {%s}\n", e->interpreter); |
1da177e4 | 501 | |
6b899c4e | 502 | /* Parse the 'flags' field. */ |
e6084d4a | 503 | p = check_special_flags(p, e); |
1da177e4 LT |
504 | if (*p == '\n') |
505 | p++; | |
506 | if (p != buf + count) | |
e6084d4a MF |
507 | goto einval; |
508 | ||
1da177e4 LT |
509 | return e; |
510 | ||
511 | out: | |
512 | return ERR_PTR(err); | |
513 | ||
e6084d4a | 514 | efault: |
1da177e4 LT |
515 | kfree(e); |
516 | return ERR_PTR(-EFAULT); | |
e6084d4a | 517 | einval: |
1da177e4 LT |
518 | kfree(e); |
519 | return ERR_PTR(-EINVAL); | |
520 | } | |
521 | ||
522 | /* | |
523 | * Set status of entry/binfmt_misc: | |
524 | * '1' enables, '0' disables and '-1' clears entry/binfmt_misc | |
525 | */ | |
526 | static int parse_command(const char __user *buffer, size_t count) | |
527 | { | |
528 | char s[4]; | |
529 | ||
1da177e4 LT |
530 | if (count > 3) |
531 | return -EINVAL; | |
532 | if (copy_from_user(s, buffer, count)) | |
533 | return -EFAULT; | |
de8288b1 AB |
534 | if (!count) |
535 | return 0; | |
e6084d4a | 536 | if (s[count - 1] == '\n') |
1da177e4 LT |
537 | count--; |
538 | if (count == 1 && s[0] == '0') | |
539 | return 1; | |
540 | if (count == 1 && s[0] == '1') | |
541 | return 2; | |
542 | if (count == 2 && s[0] == '-' && s[1] == '1') | |
543 | return 3; | |
544 | return -EINVAL; | |
545 | } | |
546 | ||
547 | /* generic stuff */ | |
548 | ||
549 | static void entry_status(Node *e, char *page) | |
550 | { | |
6ceafb88 RV |
551 | char *dp = page; |
552 | const char *status = "disabled"; | |
1da177e4 LT |
553 | |
554 | if (test_bit(Enabled, &e->flags)) | |
555 | status = "enabled"; | |
556 | ||
557 | if (!VERBOSE_STATUS) { | |
558 | sprintf(page, "%s\n", status); | |
559 | return; | |
560 | } | |
561 | ||
6ceafb88 | 562 | dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter); |
1da177e4 LT |
563 | |
564 | /* print the special flags */ | |
6ceafb88 | 565 | dp += sprintf(dp, "flags: "); |
e6084d4a MF |
566 | if (e->flags & MISC_FMT_PRESERVE_ARGV0) |
567 | *dp++ = 'P'; | |
568 | if (e->flags & MISC_FMT_OPEN_BINARY) | |
569 | *dp++ = 'O'; | |
570 | if (e->flags & MISC_FMT_CREDENTIALS) | |
571 | *dp++ = 'C'; | |
948b701a JB |
572 | if (e->flags & MISC_FMT_OPEN_FILE) |
573 | *dp++ = 'F'; | |
e6084d4a | 574 | *dp++ = '\n'; |
1da177e4 LT |
575 | |
576 | if (!test_bit(Magic, &e->flags)) { | |
577 | sprintf(dp, "extension .%s\n", e->magic); | |
578 | } else { | |
6ceafb88 RV |
579 | dp += sprintf(dp, "offset %i\nmagic ", e->offset); |
580 | dp = bin2hex(dp, e->magic, e->size); | |
1da177e4 | 581 | if (e->mask) { |
6ceafb88 RV |
582 | dp += sprintf(dp, "\nmask "); |
583 | dp = bin2hex(dp, e->mask, e->size); | |
1da177e4 LT |
584 | } |
585 | *dp++ = '\n'; | |
586 | *dp = '\0'; | |
587 | } | |
588 | } | |
589 | ||
590 | static struct inode *bm_get_inode(struct super_block *sb, int mode) | |
591 | { | |
e6084d4a | 592 | struct inode *inode = new_inode(sb); |
1da177e4 LT |
593 | |
594 | if (inode) { | |
85fe4025 | 595 | inode->i_ino = get_next_ino(); |
1da177e4 | 596 | inode->i_mode = mode; |
2276e5ba | 597 | inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode); |
1da177e4 LT |
598 | } |
599 | return inode; | |
600 | } | |
601 | ||
1c5976ef CB |
602 | /** |
603 | * bm_evict_inode - cleanup data associated with @inode | |
604 | * @inode: inode to which the data is attached | |
605 | * | |
606 | * Cleanup the binary type handler data associated with @inode if a binary type | |
607 | * entry is removed or the filesystem is unmounted and the super block is | |
608 | * shutdown. | |
609 | * | |
610 | * If the ->evict call was not caused by a super block shutdown but by a write | |
611 | * to remove the entry or all entries via bm_{entry,status}_write() the entry | |
612 | * will have already been removed from the list. We keep the list_empty() check | |
613 | * to make that explicit. | |
614 | */ | |
b57922d9 | 615 | static void bm_evict_inode(struct inode *inode) |
1da177e4 | 616 | { |
83f91827 ON |
617 | Node *e = inode->i_private; |
618 | ||
dbd5768f | 619 | clear_inode(inode); |
1c5976ef CB |
620 | |
621 | if (e) { | |
622 | write_lock(&entries_lock); | |
623 | if (!list_empty(&e->list)) | |
624 | list_del_init(&e->list); | |
625 | write_unlock(&entries_lock); | |
626 | put_binfmt_handler(e); | |
627 | } | |
1da177e4 LT |
628 | } |
629 | ||
1c5976ef CB |
630 | /** |
631 | * unlink_binfmt_dentry - remove the dentry for the binary type handler | |
632 | * @dentry: dentry associated with the binary type handler | |
633 | * | |
634 | * Do the actual filesystem work to remove a dentry for a registered binary | |
635 | * type handler. Since binfmt_misc only allows simple files to be created | |
636 | * directly under the root dentry of the filesystem we ensure that we are | |
637 | * indeed passed a dentry directly beneath the root dentry, that the inode | |
638 | * associated with the root dentry is locked, and that it is a regular file we | |
639 | * are asked to remove. | |
640 | */ | |
641 | static void unlink_binfmt_dentry(struct dentry *dentry) | |
1da177e4 | 642 | { |
1c5976ef CB |
643 | struct dentry *parent = dentry->d_parent; |
644 | struct inode *inode, *parent_inode; | |
645 | ||
646 | /* All entries are immediate descendants of the root dentry. */ | |
647 | if (WARN_ON_ONCE(dentry->d_sb->s_root != parent)) | |
648 | return; | |
1da177e4 | 649 | |
1c5976ef CB |
650 | /* We only expect to be called on regular files. */ |
651 | inode = d_inode(dentry); | |
652 | if (WARN_ON_ONCE(!S_ISREG(inode->i_mode))) | |
653 | return; | |
654 | ||
655 | /* The parent inode must be locked. */ | |
656 | parent_inode = d_inode(parent); | |
657 | if (WARN_ON_ONCE(!inode_is_locked(parent_inode))) | |
658 | return; | |
659 | ||
660 | if (simple_positive(dentry)) { | |
661 | dget(dentry); | |
662 | simple_unlink(parent_inode, dentry); | |
663 | d_delete(dentry); | |
664 | dput(dentry); | |
665 | } | |
666 | } | |
667 | ||
668 | /** | |
669 | * remove_binfmt_handler - remove a binary type handler | |
670 | * @misc: handle to binfmt_misc instance | |
671 | * @e: binary type handler to remove | |
672 | * | |
673 | * Remove a binary type handler from the list of binary type handlers and | |
674 | * remove its associated dentry. This is called from | |
675 | * binfmt_{entry,status}_write(). In the future, we might want to think about | |
676 | * adding a proper ->unlink() method to binfmt_misc instead of forcing caller's | |
677 | * to use writes to files in order to delete binary type handlers. But it has | |
678 | * worked for so long that it's not a pressing issue. | |
679 | */ | |
680 | static void remove_binfmt_handler(Node *e) | |
681 | { | |
1da177e4 | 682 | write_lock(&entries_lock); |
baba1b29 | 683 | list_del_init(&e->list); |
1da177e4 | 684 | write_unlock(&entries_lock); |
1c5976ef | 685 | unlink_binfmt_dentry(e->dentry); |
1da177e4 LT |
686 | } |
687 | ||
688 | /* /<entry> */ | |
689 | ||
690 | static ssize_t | |
e6084d4a | 691 | bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
1da177e4 | 692 | { |
496ad9aa | 693 | Node *e = file_inode(file)->i_private; |
1da177e4 LT |
694 | ssize_t res; |
695 | char *page; | |
1da177e4 | 696 | |
e6084d4a MF |
697 | page = (char *) __get_free_page(GFP_KERNEL); |
698 | if (!page) | |
1da177e4 LT |
699 | return -ENOMEM; |
700 | ||
701 | entry_status(e, page); | |
1da177e4 | 702 | |
6e2c10a1 AM |
703 | res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page)); |
704 | ||
1da177e4 LT |
705 | free_page((unsigned long) page); |
706 | return res; | |
707 | } | |
708 | ||
709 | static ssize_t bm_entry_write(struct file *file, const char __user *buffer, | |
710 | size_t count, loff_t *ppos) | |
711 | { | |
1c5976ef CB |
712 | struct inode *inode = file_inode(file); |
713 | Node *e = inode->i_private; | |
1da177e4 LT |
714 | int res = parse_command(buffer, count); |
715 | ||
716 | switch (res) { | |
e6084d4a MF |
717 | case 1: |
718 | /* Disable this handler. */ | |
719 | clear_bit(Enabled, &e->flags); | |
720 | break; | |
721 | case 2: | |
722 | /* Enable this handler. */ | |
723 | set_bit(Enabled, &e->flags); | |
724 | break; | |
725 | case 3: | |
726 | /* Delete this handler. */ | |
1c5976ef CB |
727 | inode = d_inode(inode->i_sb->s_root); |
728 | inode_lock(inode); | |
1da177e4 | 729 | |
1c5976ef CB |
730 | /* |
731 | * In order to add new element or remove elements from the list | |
732 | * via bm_{entry,register,status}_write() inode_lock() on the | |
733 | * root inode must be held. | |
734 | * The lock is exclusive ensuring that the list can't be | |
735 | * modified. Only load_misc_binary() can access but does so | |
736 | * read-only. So we only need to take the write lock when we | |
737 | * actually remove the entry from the list. | |
738 | */ | |
baba1b29 | 739 | if (!list_empty(&e->list)) |
1c5976ef | 740 | remove_binfmt_handler(e); |
1da177e4 | 741 | |
1c5976ef | 742 | inode_unlock(inode); |
e6084d4a MF |
743 | break; |
744 | default: | |
745 | return res; | |
1da177e4 | 746 | } |
e6084d4a | 747 | |
1da177e4 LT |
748 | return count; |
749 | } | |
750 | ||
4b6f5d20 | 751 | static const struct file_operations bm_entry_operations = { |
1da177e4 LT |
752 | .read = bm_entry_read, |
753 | .write = bm_entry_write, | |
6038f373 | 754 | .llseek = default_llseek, |
1da177e4 LT |
755 | }; |
756 | ||
757 | /* /register */ | |
758 | ||
759 | static ssize_t bm_register_write(struct file *file, const char __user *buffer, | |
760 | size_t count, loff_t *ppos) | |
761 | { | |
762 | Node *e; | |
763 | struct inode *inode; | |
ea7d4c04 AV |
764 | struct super_block *sb = file_inode(file)->i_sb; |
765 | struct dentry *root = sb->s_root, *dentry; | |
1da177e4 | 766 | int err = 0; |
e7850f4d | 767 | struct file *f = NULL; |
1da177e4 LT |
768 | |
769 | e = create_entry(buffer, count); | |
770 | ||
771 | if (IS_ERR(e)) | |
772 | return PTR_ERR(e); | |
773 | ||
e7850f4d LR |
774 | if (e->flags & MISC_FMT_OPEN_FILE) { |
775 | f = open_exec(e->interpreter); | |
776 | if (IS_ERR(f)) { | |
777 | pr_notice("register: failed to install interpreter file %s\n", | |
778 | e->interpreter); | |
779 | kfree(e); | |
780 | return PTR_ERR(f); | |
781 | } | |
782 | e->interp_file = f; | |
783 | } | |
784 | ||
5955102c | 785 | inode_lock(d_inode(root)); |
1da177e4 LT |
786 | dentry = lookup_one_len(e->name, root, strlen(e->name)); |
787 | err = PTR_ERR(dentry); | |
788 | if (IS_ERR(dentry)) | |
789 | goto out; | |
790 | ||
791 | err = -EEXIST; | |
75c3cfa8 | 792 | if (d_really_is_positive(dentry)) |
1da177e4 LT |
793 | goto out2; |
794 | ||
795 | inode = bm_get_inode(sb, S_IFREG | 0644); | |
796 | ||
797 | err = -ENOMEM; | |
798 | if (!inode) | |
799 | goto out2; | |
800 | ||
1c5976ef | 801 | refcount_set(&e->users, 1); |
1da177e4 | 802 | e->dentry = dget(dentry); |
8e18e294 | 803 | inode->i_private = e; |
1da177e4 LT |
804 | inode->i_fop = &bm_entry_operations; |
805 | ||
806 | d_instantiate(dentry, inode); | |
807 | write_lock(&entries_lock); | |
808 | list_add(&e->list, &entries); | |
809 | write_unlock(&entries_lock); | |
810 | ||
811 | err = 0; | |
812 | out2: | |
813 | dput(dentry); | |
814 | out: | |
5955102c | 815 | inode_unlock(d_inode(root)); |
1da177e4 LT |
816 | |
817 | if (err) { | |
e7850f4d LR |
818 | if (f) |
819 | filp_close(f, NULL); | |
1da177e4 | 820 | kfree(e); |
948b701a | 821 | return err; |
1da177e4 LT |
822 | } |
823 | return count; | |
824 | } | |
825 | ||
4b6f5d20 | 826 | static const struct file_operations bm_register_operations = { |
1da177e4 | 827 | .write = bm_register_write, |
6038f373 | 828 | .llseek = noop_llseek, |
1da177e4 LT |
829 | }; |
830 | ||
831 | /* /status */ | |
832 | ||
833 | static ssize_t | |
834 | bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
835 | { | |
87113e80 | 836 | char *s = enabled ? "enabled\n" : "disabled\n"; |
1da177e4 | 837 | |
92f4c701 | 838 | return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); |
1da177e4 LT |
839 | } |
840 | ||
e6084d4a | 841 | static ssize_t bm_status_write(struct file *file, const char __user *buffer, |
1da177e4 LT |
842 | size_t count, loff_t *ppos) |
843 | { | |
844 | int res = parse_command(buffer, count); | |
1c5976ef CB |
845 | Node *e, *next; |
846 | struct inode *inode; | |
1da177e4 LT |
847 | |
848 | switch (res) { | |
e6084d4a MF |
849 | case 1: |
850 | /* Disable all handlers. */ | |
851 | enabled = 0; | |
852 | break; | |
853 | case 2: | |
854 | /* Enable all handlers. */ | |
855 | enabled = 1; | |
856 | break; | |
857 | case 3: | |
858 | /* Delete all handlers. */ | |
1c5976ef CB |
859 | inode = d_inode(file_inode(file)->i_sb->s_root); |
860 | inode_lock(inode); | |
1da177e4 | 861 | |
1c5976ef CB |
862 | /* |
863 | * In order to add new element or remove elements from the list | |
864 | * via bm_{entry,register,status}_write() inode_lock() on the | |
865 | * root inode must be held. | |
866 | * The lock is exclusive ensuring that the list can't be | |
867 | * modified. Only load_misc_binary() can access but does so | |
868 | * read-only. So we only need to take the write lock when we | |
869 | * actually remove the entry from the list. | |
870 | */ | |
871 | list_for_each_entry_safe(e, next, &entries, list) | |
872 | remove_binfmt_handler(e); | |
1da177e4 | 873 | |
1c5976ef | 874 | inode_unlock(inode); |
e6084d4a MF |
875 | break; |
876 | default: | |
877 | return res; | |
1da177e4 | 878 | } |
e6084d4a | 879 | |
1da177e4 LT |
880 | return count; |
881 | } | |
882 | ||
4b6f5d20 | 883 | static const struct file_operations bm_status_operations = { |
1da177e4 LT |
884 | .read = bm_status_read, |
885 | .write = bm_status_write, | |
6038f373 | 886 | .llseek = default_llseek, |
1da177e4 LT |
887 | }; |
888 | ||
889 | /* Superblock handling */ | |
890 | ||
ee9b6d61 | 891 | static const struct super_operations s_ops = { |
1da177e4 | 892 | .statfs = simple_statfs, |
b57922d9 | 893 | .evict_inode = bm_evict_inode, |
1da177e4 LT |
894 | }; |
895 | ||
bc99a664 | 896 | static int bm_fill_super(struct super_block *sb, struct fs_context *fc) |
1da177e4 | 897 | { |
e6084d4a | 898 | int err; |
cda37124 | 899 | static const struct tree_descr bm_files[] = { |
1a1c9bb4 JL |
900 | [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO}, |
901 | [3] = {"register", &bm_register_operations, S_IWUSR}, | |
1da177e4 LT |
902 | /* last one */ {""} |
903 | }; | |
e6084d4a MF |
904 | |
905 | err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files); | |
1da177e4 LT |
906 | if (!err) |
907 | sb->s_op = &s_ops; | |
908 | return err; | |
909 | } | |
910 | ||
bc99a664 | 911 | static int bm_get_tree(struct fs_context *fc) |
1da177e4 | 912 | { |
bc99a664 DH |
913 | return get_tree_single(fc, bm_fill_super); |
914 | } | |
915 | ||
916 | static const struct fs_context_operations bm_context_ops = { | |
917 | .get_tree = bm_get_tree, | |
918 | }; | |
919 | ||
920 | static int bm_init_fs_context(struct fs_context *fc) | |
921 | { | |
922 | fc->ops = &bm_context_ops; | |
923 | return 0; | |
1da177e4 LT |
924 | } |
925 | ||
926 | static struct linux_binfmt misc_format = { | |
927 | .module = THIS_MODULE, | |
928 | .load_binary = load_misc_binary, | |
929 | }; | |
930 | ||
931 | static struct file_system_type bm_fs_type = { | |
932 | .owner = THIS_MODULE, | |
933 | .name = "binfmt_misc", | |
bc99a664 | 934 | .init_fs_context = bm_init_fs_context, |
1da177e4 LT |
935 | .kill_sb = kill_litter_super, |
936 | }; | |
7f78e035 | 937 | MODULE_ALIAS_FS("binfmt_misc"); |
1da177e4 LT |
938 | |
939 | static int __init init_misc_binfmt(void) | |
940 | { | |
941 | int err = register_filesystem(&bm_fs_type); | |
8fc3dc5a AV |
942 | if (!err) |
943 | insert_binfmt(&misc_format); | |
b42bc9a3 | 944 | return err; |
1da177e4 LT |
945 | } |
946 | ||
947 | static void __exit exit_misc_binfmt(void) | |
948 | { | |
949 | unregister_binfmt(&misc_format); | |
950 | unregister_filesystem(&bm_fs_type); | |
951 | } | |
952 | ||
953 | core_initcall(init_misc_binfmt); | |
954 | module_exit(exit_misc_binfmt); | |
955 | MODULE_LICENSE("GPL"); |