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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Mike Frysingere6084d42014-12-10 15:52:10 -08002 * binfmt_misc.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
Mike Frysingere6084d42014-12-10 15:52:10 -08004 * Copyright (C) 1997 Richard Günther
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
Mike Frysingere6084d42014-12-10 15:52:10 -08006 * binfmt_misc detects binaries via a magic or filename extension and invokes
7 * a specified wrapper. See Documentation/binfmt_misc.txt for more details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 */
9
Mike Frysinger6b899c42014-12-10 15:52:08 -080010#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -070012#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/module.h>
14#include <linux/init.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040015#include <linux/sched.h>
Muthu Kumarb502bd12012-03-23 15:01:50 -070016#include <linux/magic.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/binfmts.h>
18#include <linux/slab.h>
19#include <linux/ctype.h>
Andy Shevchenko8d82e182013-04-30 15:27:33 -070020#include <linux/string_helpers.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/file.h>
22#include <linux/pagemap.h>
23#include <linux/namei.h>
24#include <linux/mount.h>
25#include <linux/syscalls.h>
Akinobu Mita6e2c10a2008-07-23 21:29:15 -070026#include <linux/fs.h>
Mike Frysinger6b899c42014-12-10 15:52:08 -080027#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
Mike Frysinger6b899c42014-12-10 15:52:08 -080029#ifdef DEBUG
30# define USE_DEBUG 1
31#else
32# define USE_DEBUG 0
33#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
35enum {
36 VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
37};
38
39static LIST_HEAD(entries);
40static int enabled = 1;
41
42enum {Enabled, Magic};
Mike Frysingere6084d42014-12-10 15:52:10 -080043#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
44#define MISC_FMT_OPEN_BINARY (1 << 30)
45#define MISC_FMT_CREDENTIALS (1 << 29)
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
47typedef struct {
48 struct list_head list;
49 unsigned long flags; /* type, status, etc. */
50 int offset; /* offset of magic */
51 int size; /* size of magic/mask */
52 char *magic; /* magic or filename extension */
53 char *mask; /* mask, NULL for exact match */
54 char *interpreter; /* filename of interpreter */
55 char *name;
56 struct dentry *dentry;
57} Node;
58
59static DEFINE_RWLOCK(entries_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -040060static struct file_system_type bm_fs_type;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061static struct vfsmount *bm_mnt;
62static int entry_count;
63
Mike Frysingerbbaecc02014-10-13 15:52:03 -070064/*
65 * Max length of the register string. Determined by:
66 * - 7 delimiters
67 * - name: ~50 bytes
68 * - type: 1 byte
69 * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
70 * - magic: 128 bytes (512 in escaped form)
71 * - mask: 128 bytes (512 in escaped form)
72 * - interp: ~50 bytes
73 * - flags: 5 bytes
74 * Round that up a bit, and then back off to hold the internal data
75 * (like struct Node).
76 */
77#define MAX_REGISTER_LENGTH 1920
78
79/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 * Check if we support the binfmt
81 * if we do, return the node, else NULL
82 * locking is done in load_misc_binary
83 */
84static Node *check_file(struct linux_binprm *bprm)
85{
86 char *p = strrchr(bprm->interp, '.');
87 struct list_head *l;
88
Mike Frysinger6b899c42014-12-10 15:52:08 -080089 /* Walk all the registered handlers. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 list_for_each(l, &entries) {
91 Node *e = list_entry(l, Node, list);
92 char *s;
93 int j;
94
Mike Frysinger6b899c42014-12-10 15:52:08 -080095 /* Make sure this one is currently enabled. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 if (!test_bit(Enabled, &e->flags))
97 continue;
98
Mike Frysinger6b899c42014-12-10 15:52:08 -080099 /* Do matching based on extension if applicable. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 if (!test_bit(Magic, &e->flags)) {
101 if (p && !strcmp(e->magic, p + 1))
102 return e;
103 continue;
104 }
105
Mike Frysinger6b899c42014-12-10 15:52:08 -0800106 /* Do matching based on magic & mask. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 s = bprm->buf + e->offset;
108 if (e->mask) {
109 for (j = 0; j < e->size; j++)
110 if ((*s++ ^ e->magic[j]) & e->mask[j])
111 break;
112 } else {
113 for (j = 0; j < e->size; j++)
114 if ((*s++ ^ e->magic[j]))
115 break;
116 }
117 if (j == e->size)
118 return e;
119 }
120 return NULL;
121}
122
123/*
124 * the loader itself
125 */
Al Viro71613c32012-10-20 22:00:48 -0400126static int load_misc_binary(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127{
128 Node *fmt;
Mike Frysingere6084d42014-12-10 15:52:10 -0800129 struct file *interp_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 char iname[BINPRM_BUF_SIZE];
David Howellsd7627462010-08-17 23:52:56 +0100131 const char *iname_addr = iname;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 int retval;
133 int fd_binary = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
135 retval = -ENOEXEC;
136 if (!enabled)
Mike Frysingere6084d42014-12-10 15:52:10 -0800137 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138
139 /* to keep locking time low, we copy the interpreter string */
140 read_lock(&entries_lock);
141 fmt = check_file(bprm);
142 if (fmt)
143 strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
144 read_unlock(&entries_lock);
145 if (!fmt)
Mike Frysingere6084d42014-12-10 15:52:10 -0800146 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
David Drysdale51f39a12014-12-12 16:57:29 -0800148 /* Need to be able to load the file after exec */
149 if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
150 return -ENOENT;
151
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700153 retval = remove_arg_zero(bprm);
154 if (retval)
Mike Frysingere6084d42014-12-10 15:52:10 -0800155 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 }
157
158 if (fmt->flags & MISC_FMT_OPEN_BINARY) {
159
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 /* if the binary should be opened on behalf of the
161 * interpreter than keep it open and assign descriptor
Mike Frysingere6084d42014-12-10 15:52:10 -0800162 * to it
163 */
Yann Droneaudc6cb8982014-12-10 15:45:42 -0800164 fd_binary = get_unused_fd_flags(0);
Mike Frysingere6084d42014-12-10 15:52:10 -0800165 if (fd_binary < 0) {
166 retval = fd_binary;
167 goto ret;
168 }
169 fd_install(fd_binary, bprm->file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
171 /* if the binary is not readable than enforce mm->dumpable=0
172 regardless of the interpreter's permissions */
Al Viro1b5d7832011-06-19 12:49:47 -0400173 would_dump(bprm, bprm->file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
175 allow_write_access(bprm->file);
176 bprm->file = NULL;
177
178 /* mark the bprm that fd should be passed to interp */
179 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
180 bprm->interp_data = fd_binary;
181
Mike Frysingere6084d42014-12-10 15:52:10 -0800182 } else {
183 allow_write_access(bprm->file);
184 fput(bprm->file);
185 bprm->file = NULL;
186 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 /* make argv[1] be the path to the binary */
Mike Frysingere6084d42014-12-10 15:52:10 -0800188 retval = copy_strings_kernel(1, &bprm->interp, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800190 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 bprm->argc++;
192
193 /* add the interp as argv[0] */
Mike Frysingere6084d42014-12-10 15:52:10 -0800194 retval = copy_strings_kernel(1, &iname_addr, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800196 goto error;
197 bprm->argc++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
Kees Cookb66c5982012-12-20 15:05:16 -0800199 /* Update interp in case binfmt_script needs it. */
200 retval = bprm_change_interp(iname, bprm);
201 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800202 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
Mike Frysingere6084d42014-12-10 15:52:10 -0800204 interp_file = open_exec(iname);
205 retval = PTR_ERR(interp_file);
206 if (IS_ERR(interp_file))
207 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208
209 bprm->file = interp_file;
210 if (fmt->flags & MISC_FMT_CREDENTIALS) {
211 /*
212 * No need to call prepare_binprm(), it's already been
213 * done. bprm->buf is stale, update from interp_file.
214 */
215 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
216 retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
217 } else
Mike Frysingere6084d42014-12-10 15:52:10 -0800218 retval = prepare_binprm(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219
220 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800221 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222
Al Viro3c456bf2012-10-20 21:53:31 -0400223 retval = search_binary_handler(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800225 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226
Mike Frysingere6084d42014-12-10 15:52:10 -0800227ret:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 return retval;
Mike Frysingere6084d42014-12-10 15:52:10 -0800229error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 if (fd_binary > 0)
231 sys_close(fd_binary);
232 bprm->interp_flags = 0;
233 bprm->interp_data = 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800234 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235}
236
237/* Command parsers */
238
239/*
240 * parses and copies one argument enclosed in del from *sp to *dp,
241 * recognising the \x special.
242 * returns pointer to the copied argument or NULL in case of an
243 * error (and sets err) or null argument length.
244 */
245static char *scanarg(char *s, char del)
246{
247 char c;
248
249 while ((c = *s++) != del) {
250 if (c == '\\' && *s == 'x') {
251 s++;
252 if (!isxdigit(*s++))
253 return NULL;
254 if (!isxdigit(*s++))
255 return NULL;
256 }
257 }
Al Viro7d65cf12014-12-17 05:29:16 -0500258 s[-1] ='\0';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 return s;
260}
261
Mike Frysingere6084d42014-12-10 15:52:10 -0800262static char *check_special_flags(char *sfs, Node *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263{
Mike Frysingere6084d42014-12-10 15:52:10 -0800264 char *p = sfs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 int cont = 1;
266
267 /* special flags */
268 while (cont) {
269 switch (*p) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800270 case 'P':
271 pr_debug("register: flag: P (preserve argv0)\n");
272 p++;
273 e->flags |= MISC_FMT_PRESERVE_ARGV0;
274 break;
275 case 'O':
276 pr_debug("register: flag: O (open binary)\n");
277 p++;
278 e->flags |= MISC_FMT_OPEN_BINARY;
279 break;
280 case 'C':
281 pr_debug("register: flag: C (preserve creds)\n");
282 p++;
283 /* this flags also implies the
284 open-binary flag */
285 e->flags |= (MISC_FMT_CREDENTIALS |
286 MISC_FMT_OPEN_BINARY);
287 break;
288 default:
289 cont = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 }
291 }
292
293 return p;
294}
Mike Frysingere6084d42014-12-10 15:52:10 -0800295
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296/*
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
Mike Frysinger6b899c42014-12-10 15:52:08 -0800308 pr_debug("register: received %zu bytes\n", count);
309
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 /* some sanity checks */
311 err = -EINVAL;
Mike Frysingerbbaecc02014-10-13 15:52:03 -0700312 if ((count < 11) || (count > MAX_REGISTER_LENGTH))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 goto out;
314
315 err = -ENOMEM;
316 memsize = sizeof(Node) + count + 8;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800317 e = kmalloc(memsize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 if (!e)
319 goto out;
320
321 p = buf = (char *)e + sizeof(Node);
322
323 memset(e, 0, sizeof(Node));
324 if (copy_from_user(buf, buffer, count))
Mike Frysingere6084d42014-12-10 15:52:10 -0800325 goto efault;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326
327 del = *p++; /* delimeter */
328
Mike Frysinger6b899c42014-12-10 15:52:08 -0800329 pr_debug("register: delim: %#x {%c}\n", del, del);
330
331 /* Pad the buffer with the delim to simplify parsing below. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800332 memset(buf + count, del, 8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
Mike Frysinger6b899c42014-12-10 15:52:08 -0800334 /* Parse the 'name' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 e->name = p;
336 p = strchr(p, del);
337 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800338 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 *p++ = '\0';
340 if (!e->name[0] ||
341 !strcmp(e->name, ".") ||
342 !strcmp(e->name, "..") ||
343 strchr(e->name, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800344 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800345
346 pr_debug("register: name: {%s}\n", e->name);
347
348 /* Parse the 'type' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 switch (*p++) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800350 case 'E':
351 pr_debug("register: type: E (extension)\n");
352 e->flags = 1 << Enabled;
353 break;
354 case 'M':
355 pr_debug("register: type: M (magic)\n");
356 e->flags = (1 << Enabled) | (1 << Magic);
357 break;
358 default:
Mike Frysingere6084d42014-12-10 15:52:10 -0800359 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 }
361 if (*p++ != del)
Mike Frysingere6084d42014-12-10 15:52:10 -0800362 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 if (test_bit(Magic, &e->flags)) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800365 /* Handle the 'M' (magic) format. */
366 char *s;
367
368 /* Parse the 'offset' field. */
369 s = strchr(p, del);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370 if (!s)
Mike Frysingere6084d42014-12-10 15:52:10 -0800371 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372 *s++ = '\0';
373 e->offset = simple_strtoul(p, &p, 10);
374 if (*p++)
Mike Frysingere6084d42014-12-10 15:52:10 -0800375 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800376 pr_debug("register: offset: %#x\n", e->offset);
377
378 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 e->magic = p;
380 p = scanarg(p, del);
381 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800382 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500383 if (!e->magic[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800384 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800385 if (USE_DEBUG)
386 print_hex_dump_bytes(
387 KBUILD_MODNAME ": register: magic[raw]: ",
388 DUMP_PREFIX_NONE, e->magic, p - e->magic);
389
390 /* Parse the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 e->mask = p;
392 p = scanarg(p, del);
393 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800394 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500395 if (!e->mask[0]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 e->mask = NULL;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800397 pr_debug("register: mask[raw]: none\n");
398 } else if (USE_DEBUG)
399 print_hex_dump_bytes(
400 KBUILD_MODNAME ": register: mask[raw]: ",
401 DUMP_PREFIX_NONE, e->mask, p - e->mask);
402
403 /*
404 * Decode the magic & mask fields.
405 * Note: while we might have accepted embedded NUL bytes from
406 * above, the unescape helpers here will stop at the first one
407 * it encounters.
408 */
Andy Shevchenko8d82e182013-04-30 15:27:33 -0700409 e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
410 if (e->mask &&
411 string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
Mike Frysingere6084d42014-12-10 15:52:10 -0800412 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 if (e->size + e->offset > BINPRM_BUF_SIZE)
Mike Frysingere6084d42014-12-10 15:52:10 -0800414 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800415 pr_debug("register: magic/mask length: %i\n", e->size);
416 if (USE_DEBUG) {
417 print_hex_dump_bytes(
418 KBUILD_MODNAME ": register: magic[decoded]: ",
419 DUMP_PREFIX_NONE, e->magic, e->size);
420
421 if (e->mask) {
422 int i;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800423 char *masked = kmalloc(e->size, GFP_KERNEL);
Mike Frysinger6b899c42014-12-10 15:52:08 -0800424
425 print_hex_dump_bytes(
426 KBUILD_MODNAME ": register: mask[decoded]: ",
427 DUMP_PREFIX_NONE, e->mask, e->size);
428
429 if (masked) {
430 for (i = 0; i < e->size; ++i)
431 masked[i] = e->magic[i] & e->mask[i];
432 print_hex_dump_bytes(
433 KBUILD_MODNAME ": register: magic[masked]: ",
434 DUMP_PREFIX_NONE, masked, e->size);
435
436 kfree(masked);
437 }
438 }
439 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 } else {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800441 /* Handle the 'E' (extension) format. */
442
443 /* Skip the 'offset' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 p = strchr(p, del);
445 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800446 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447 *p++ = '\0';
Mike Frysinger6b899c42014-12-10 15:52:08 -0800448
449 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 e->magic = p;
451 p = strchr(p, del);
452 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800453 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 *p++ = '\0';
455 if (!e->magic[0] || strchr(e->magic, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800456 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800457 pr_debug("register: extension: {%s}\n", e->magic);
458
459 /* Skip the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 p = strchr(p, del);
461 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800462 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 *p++ = '\0';
464 }
Mike Frysinger6b899c42014-12-10 15:52:08 -0800465
466 /* Parse the 'interpreter' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 e->interpreter = p;
468 p = strchr(p, del);
469 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800470 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 *p++ = '\0';
472 if (!e->interpreter[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800473 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800474 pr_debug("register: interpreter: {%s}\n", e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475
Mike Frysinger6b899c42014-12-10 15:52:08 -0800476 /* Parse the 'flags' field. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800477 p = check_special_flags(p, e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 if (*p == '\n')
479 p++;
480 if (p != buf + count)
Mike Frysingere6084d42014-12-10 15:52:10 -0800481 goto einval;
482
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 return e;
484
485out:
486 return ERR_PTR(err);
487
Mike Frysingere6084d42014-12-10 15:52:10 -0800488efault:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489 kfree(e);
490 return ERR_PTR(-EFAULT);
Mike Frysingere6084d42014-12-10 15:52:10 -0800491einval:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 kfree(e);
493 return ERR_PTR(-EINVAL);
494}
495
496/*
497 * Set status of entry/binfmt_misc:
498 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
499 */
500static int parse_command(const char __user *buffer, size_t count)
501{
502 char s[4];
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 if (count > 3)
505 return -EINVAL;
506 if (copy_from_user(s, buffer, count))
507 return -EFAULT;
Arnd Bergmannde8288b2014-10-13 15:52:08 -0700508 if (!count)
509 return 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800510 if (s[count - 1] == '\n')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 count--;
512 if (count == 1 && s[0] == '0')
513 return 1;
514 if (count == 1 && s[0] == '1')
515 return 2;
516 if (count == 2 && s[0] == '-' && s[1] == '1')
517 return 3;
518 return -EINVAL;
519}
520
521/* generic stuff */
522
523static void entry_status(Node *e, char *page)
524{
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700525 char *dp = page;
526 const char *status = "disabled";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527
528 if (test_bit(Enabled, &e->flags))
529 status = "enabled";
530
531 if (!VERBOSE_STATUS) {
532 sprintf(page, "%s\n", status);
533 return;
534 }
535
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700536 dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537
538 /* print the special flags */
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700539 dp += sprintf(dp, "flags: ");
Mike Frysingere6084d42014-12-10 15:52:10 -0800540 if (e->flags & MISC_FMT_PRESERVE_ARGV0)
541 *dp++ = 'P';
542 if (e->flags & MISC_FMT_OPEN_BINARY)
543 *dp++ = 'O';
544 if (e->flags & MISC_FMT_CREDENTIALS)
545 *dp++ = 'C';
546 *dp++ = '\n';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547
548 if (!test_bit(Magic, &e->flags)) {
549 sprintf(dp, "extension .%s\n", e->magic);
550 } else {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700551 dp += sprintf(dp, "offset %i\nmagic ", e->offset);
552 dp = bin2hex(dp, e->magic, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 if (e->mask) {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700554 dp += sprintf(dp, "\nmask ");
555 dp = bin2hex(dp, e->mask, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 }
557 *dp++ = '\n';
558 *dp = '\0';
559 }
560}
561
562static struct inode *bm_get_inode(struct super_block *sb, int mode)
563{
Mike Frysingere6084d42014-12-10 15:52:10 -0800564 struct inode *inode = new_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565
566 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -0400567 inode->i_ino = get_next_ino();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 inode->i_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 inode->i_atime = inode->i_mtime = inode->i_ctime =
570 current_fs_time(inode->i_sb);
571 }
572 return inode;
573}
574
Al Virob57922d2010-06-07 14:34:48 -0400575static void bm_evict_inode(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576{
Jan Karadbd57682012-05-03 14:48:02 +0200577 clear_inode(inode);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700578 kfree(inode->i_private);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579}
580
581static void kill_node(Node *e)
582{
583 struct dentry *dentry;
584
585 write_lock(&entries_lock);
586 dentry = e->dentry;
587 if (dentry) {
588 list_del_init(&e->list);
589 e->dentry = NULL;
590 }
591 write_unlock(&entries_lock);
592
593 if (dentry) {
David Howells75c3cfa2015-03-17 22:26:12 +0000594 drop_nlink(d_inode(dentry));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 d_drop(dentry);
596 dput(dentry);
597 simple_release_fs(&bm_mnt, &entry_count);
598 }
599}
600
601/* /<entry> */
602
603static ssize_t
Mike Frysingere6084d42014-12-10 15:52:10 -0800604bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605{
Al Viro496ad9a2013-01-23 17:07:38 -0500606 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 ssize_t res;
608 char *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609
Mike Frysingere6084d42014-12-10 15:52:10 -0800610 page = (char *) __get_free_page(GFP_KERNEL);
611 if (!page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 return -ENOMEM;
613
614 entry_status(e, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
Akinobu Mita6e2c10a2008-07-23 21:29:15 -0700616 res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
617
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 free_page((unsigned long) page);
619 return res;
620}
621
622static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
623 size_t count, loff_t *ppos)
624{
625 struct dentry *root;
Al Viro496ad9a2013-01-23 17:07:38 -0500626 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 int res = parse_command(buffer, count);
628
629 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800630 case 1:
631 /* Disable this handler. */
632 clear_bit(Enabled, &e->flags);
633 break;
634 case 2:
635 /* Enable this handler. */
636 set_bit(Enabled, &e->flags);
637 break;
638 case 3:
639 /* Delete this handler. */
640 root = dget(file->f_path.dentry->d_sb->s_root);
Al Viro59551022016-01-22 15:40:57 -0500641 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642
Mike Frysingere6084d42014-12-10 15:52:10 -0800643 kill_node(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644
Al Viro59551022016-01-22 15:40:57 -0500645 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800646 dput(root);
647 break;
648 default:
649 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800651
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 return count;
653}
654
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800655static const struct file_operations bm_entry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 .read = bm_entry_read,
657 .write = bm_entry_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200658 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659};
660
661/* /register */
662
663static ssize_t bm_register_write(struct file *file, const char __user *buffer,
664 size_t count, loff_t *ppos)
665{
666 Node *e;
667 struct inode *inode;
668 struct dentry *root, *dentry;
Al Virod8c95842011-12-07 18:16:57 -0500669 struct super_block *sb = file->f_path.dentry->d_sb;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 int err = 0;
671
672 e = create_entry(buffer, count);
673
674 if (IS_ERR(e))
675 return PTR_ERR(e);
676
677 root = dget(sb->s_root);
Al Viro59551022016-01-22 15:40:57 -0500678 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 dentry = lookup_one_len(e->name, root, strlen(e->name));
680 err = PTR_ERR(dentry);
681 if (IS_ERR(dentry))
682 goto out;
683
684 err = -EEXIST;
David Howells75c3cfa2015-03-17 22:26:12 +0000685 if (d_really_is_positive(dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 goto out2;
687
688 inode = bm_get_inode(sb, S_IFREG | 0644);
689
690 err = -ENOMEM;
691 if (!inode)
692 goto out2;
693
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400694 err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 if (err) {
696 iput(inode);
697 inode = NULL;
698 goto out2;
699 }
700
701 e->dentry = dget(dentry);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700702 inode->i_private = e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 inode->i_fop = &bm_entry_operations;
704
705 d_instantiate(dentry, inode);
706 write_lock(&entries_lock);
707 list_add(&e->list, &entries);
708 write_unlock(&entries_lock);
709
710 err = 0;
711out2:
712 dput(dentry);
713out:
Al Viro59551022016-01-22 15:40:57 -0500714 inode_unlock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 dput(root);
716
717 if (err) {
718 kfree(e);
719 return -EINVAL;
720 }
721 return count;
722}
723
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800724static const struct file_operations bm_register_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 .write = bm_register_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200726 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727};
728
729/* /status */
730
731static ssize_t
732bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
733{
Qinghuang Feng87113e82009-01-06 14:41:38 -0800734 char *s = enabled ? "enabled\n" : "disabled\n";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735
Akinobu Mita92f4c702007-05-09 02:33:32 -0700736 return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737}
738
Mike Frysingere6084d42014-12-10 15:52:10 -0800739static ssize_t bm_status_write(struct file *file, const char __user *buffer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 size_t count, loff_t *ppos)
741{
742 int res = parse_command(buffer, count);
743 struct dentry *root;
744
745 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800746 case 1:
747 /* Disable all handlers. */
748 enabled = 0;
749 break;
750 case 2:
751 /* Enable all handlers. */
752 enabled = 1;
753 break;
754 case 3:
755 /* Delete all handlers. */
756 root = dget(file->f_path.dentry->d_sb->s_root);
Al Viro59551022016-01-22 15:40:57 -0500757 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758
Mike Frysingere6084d42014-12-10 15:52:10 -0800759 while (!list_empty(&entries))
760 kill_node(list_entry(entries.next, Node, list));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761
Al Viro59551022016-01-22 15:40:57 -0500762 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800763 dput(root);
764 break;
765 default:
766 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800768
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 return count;
770}
771
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800772static const struct file_operations bm_status_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 .read = bm_status_read,
774 .write = bm_status_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200775 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776};
777
778/* Superblock handling */
779
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800780static const struct super_operations s_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 .statfs = simple_statfs,
Al Virob57922d2010-06-07 14:34:48 -0400782 .evict_inode = bm_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783};
784
Mike Frysingere6084d42014-12-10 15:52:10 -0800785static int bm_fill_super(struct super_block *sb, void *data, int silent)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786{
Mike Frysingere6084d42014-12-10 15:52:10 -0800787 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 static struct tree_descr bm_files[] = {
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700789 [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
790 [3] = {"register", &bm_register_operations, S_IWUSR},
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 /* last one */ {""}
792 };
Mike Frysingere6084d42014-12-10 15:52:10 -0800793
794 err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 if (!err)
796 sb->s_op = &s_ops;
797 return err;
798}
799
Al Virofc14f2f2010-07-25 01:48:30 +0400800static struct dentry *bm_mount(struct file_system_type *fs_type,
801 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802{
Al Virofc14f2f2010-07-25 01:48:30 +0400803 return mount_single(fs_type, flags, data, bm_fill_super);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804}
805
806static struct linux_binfmt misc_format = {
807 .module = THIS_MODULE,
808 .load_binary = load_misc_binary,
809};
810
811static struct file_system_type bm_fs_type = {
812 .owner = THIS_MODULE,
813 .name = "binfmt_misc",
Al Virofc14f2f2010-07-25 01:48:30 +0400814 .mount = bm_mount,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 .kill_sb = kill_litter_super,
816};
Eric W. Biederman7f78e032013-03-02 19:39:14 -0800817MODULE_ALIAS_FS("binfmt_misc");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818
819static int __init init_misc_binfmt(void)
820{
821 int err = register_filesystem(&bm_fs_type);
Al Viro8fc3dc52012-03-17 03:05:16 -0400822 if (!err)
823 insert_binfmt(&misc_format);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 return err;
825}
826
827static void __exit exit_misc_binfmt(void)
828{
829 unregister_binfmt(&misc_format);
830 unregister_filesystem(&bm_fs_type);
831}
832
833core_initcall(init_misc_binfmt);
834module_exit(exit_misc_binfmt);
835MODULE_LICENSE("GPL");