blob: 2bda9245cabe55d2a748b8de65a19ed276634944 [file] [log] [blame]
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
James Bottomley948b7012016-02-17 16:51:16 -080029#include "internal.h"
30
Mike Frysinger6b899c42014-12-10 15:52:08 -080031#ifdef DEBUG
32# define USE_DEBUG 1
33#else
34# define USE_DEBUG 0
35#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37enum {
38 VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
39};
40
41static LIST_HEAD(entries);
42static int enabled = 1;
43
44enum {Enabled, Magic};
Mike Frysingere6084d42014-12-10 15:52:10 -080045#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
46#define MISC_FMT_OPEN_BINARY (1 << 30)
47#define MISC_FMT_CREDENTIALS (1 << 29)
James Bottomley948b7012016-02-17 16:51:16 -080048#define MISC_FMT_OPEN_FILE (1 << 28)
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50typedef struct {
51 struct list_head list;
52 unsigned long flags; /* type, status, etc. */
53 int offset; /* offset of magic */
54 int size; /* size of magic/mask */
55 char *magic; /* magic or filename extension */
56 char *mask; /* mask, NULL for exact match */
57 char *interpreter; /* filename of interpreter */
58 char *name;
59 struct dentry *dentry;
James Bottomley948b7012016-02-17 16:51:16 -080060 struct file *interp_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061} Node;
62
63static DEFINE_RWLOCK(entries_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -040064static struct file_system_type bm_fs_type;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065static struct vfsmount *bm_mnt;
66static int entry_count;
67
Mike Frysingerbbaecc02014-10-13 15:52:03 -070068/*
69 * Max length of the register string. Determined by:
70 * - 7 delimiters
71 * - name: ~50 bytes
72 * - type: 1 byte
73 * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
74 * - magic: 128 bytes (512 in escaped form)
75 * - mask: 128 bytes (512 in escaped form)
76 * - interp: ~50 bytes
77 * - flags: 5 bytes
78 * Round that up a bit, and then back off to hold the internal data
79 * (like struct Node).
80 */
81#define MAX_REGISTER_LENGTH 1920
82
83/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 * Check if we support the binfmt
85 * if we do, return the node, else NULL
86 * locking is done in load_misc_binary
87 */
88static Node *check_file(struct linux_binprm *bprm)
89{
90 char *p = strrchr(bprm->interp, '.');
91 struct list_head *l;
92
Mike Frysinger6b899c42014-12-10 15:52:08 -080093 /* Walk all the registered handlers. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 list_for_each(l, &entries) {
95 Node *e = list_entry(l, Node, list);
96 char *s;
97 int j;
98
Mike Frysinger6b899c42014-12-10 15:52:08 -080099 /* Make sure this one is currently enabled. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 if (!test_bit(Enabled, &e->flags))
101 continue;
102
Mike Frysinger6b899c42014-12-10 15:52:08 -0800103 /* Do matching based on extension if applicable. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 if (!test_bit(Magic, &e->flags)) {
105 if (p && !strcmp(e->magic, p + 1))
106 return e;
107 continue;
108 }
109
Mike Frysinger6b899c42014-12-10 15:52:08 -0800110 /* Do matching based on magic & mask. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 s = bprm->buf + e->offset;
112 if (e->mask) {
113 for (j = 0; j < e->size; j++)
114 if ((*s++ ^ e->magic[j]) & e->mask[j])
115 break;
116 } else {
117 for (j = 0; j < e->size; j++)
118 if ((*s++ ^ e->magic[j]))
119 break;
120 }
121 if (j == e->size)
122 return e;
123 }
124 return NULL;
125}
126
127/*
128 * the loader itself
129 */
Al Viro71613c32012-10-20 22:00:48 -0400130static int load_misc_binary(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131{
132 Node *fmt;
Mike Frysingere6084d42014-12-10 15:52:10 -0800133 struct file *interp_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 char iname[BINPRM_BUF_SIZE];
David Howellsd7627462010-08-17 23:52:56 +0100135 const char *iname_addr = iname;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 int retval;
137 int fd_binary = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138
139 retval = -ENOEXEC;
140 if (!enabled)
Mike Frysingere6084d42014-12-10 15:52:10 -0800141 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142
143 /* to keep locking time low, we copy the interpreter string */
144 read_lock(&entries_lock);
145 fmt = check_file(bprm);
146 if (fmt)
147 strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
148 read_unlock(&entries_lock);
149 if (!fmt)
Mike Frysingere6084d42014-12-10 15:52:10 -0800150 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
David Drysdale51f39a12014-12-12 16:57:29 -0800152 /* Need to be able to load the file after exec */
153 if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
154 return -ENOENT;
155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700157 retval = remove_arg_zero(bprm);
158 if (retval)
Mike Frysingere6084d42014-12-10 15:52:10 -0800159 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 }
161
162 if (fmt->flags & MISC_FMT_OPEN_BINARY) {
163
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 /* if the binary should be opened on behalf of the
165 * interpreter than keep it open and assign descriptor
Mike Frysingere6084d42014-12-10 15:52:10 -0800166 * to it
167 */
Yann Droneaudc6cb8982014-12-10 15:45:42 -0800168 fd_binary = get_unused_fd_flags(0);
Mike Frysingere6084d42014-12-10 15:52:10 -0800169 if (fd_binary < 0) {
170 retval = fd_binary;
171 goto ret;
172 }
173 fd_install(fd_binary, bprm->file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
175 /* if the binary is not readable than enforce mm->dumpable=0
176 regardless of the interpreter's permissions */
Al Viro1b5d7832011-06-19 12:49:47 -0400177 would_dump(bprm, bprm->file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
179 allow_write_access(bprm->file);
180 bprm->file = NULL;
181
182 /* mark the bprm that fd should be passed to interp */
183 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
184 bprm->interp_data = fd_binary;
185
Mike Frysingere6084d42014-12-10 15:52:10 -0800186 } else {
187 allow_write_access(bprm->file);
188 fput(bprm->file);
189 bprm->file = NULL;
190 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 /* make argv[1] be the path to the binary */
Mike Frysingere6084d42014-12-10 15:52:10 -0800192 retval = copy_strings_kernel(1, &bprm->interp, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800194 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 bprm->argc++;
196
197 /* add the interp as argv[0] */
Mike Frysingere6084d42014-12-10 15:52:10 -0800198 retval = copy_strings_kernel(1, &iname_addr, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800200 goto error;
201 bprm->argc++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202
Kees Cookb66c5982012-12-20 15:05:16 -0800203 /* Update interp in case binfmt_script needs it. */
204 retval = bprm_change_interp(iname, bprm);
205 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800206 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207
James Bottomley948b7012016-02-17 16:51:16 -0800208 if (fmt->flags & MISC_FMT_OPEN_FILE && fmt->interp_file) {
209 interp_file = filp_clone_open(fmt->interp_file);
210 if (!IS_ERR(interp_file))
211 deny_write_access(interp_file);
212 } else {
213 interp_file = open_exec(iname);
214 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800215 retval = PTR_ERR(interp_file);
216 if (IS_ERR(interp_file))
217 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218
219 bprm->file = interp_file;
220 if (fmt->flags & MISC_FMT_CREDENTIALS) {
221 /*
222 * No need to call prepare_binprm(), it's already been
223 * done. bprm->buf is stale, update from interp_file.
224 */
225 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
226 retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
227 } else
Mike Frysingere6084d42014-12-10 15:52:10 -0800228 retval = prepare_binprm(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229
230 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800231 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
Al Viro3c456bf2012-10-20 21:53:31 -0400233 retval = search_binary_handler(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800235 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236
Mike Frysingere6084d42014-12-10 15:52:10 -0800237ret:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 return retval;
Mike Frysingere6084d42014-12-10 15:52:10 -0800239error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 if (fd_binary > 0)
241 sys_close(fd_binary);
242 bprm->interp_flags = 0;
243 bprm->interp_data = 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800244 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245}
246
247/* Command parsers */
248
249/*
250 * parses and copies one argument enclosed in del from *sp to *dp,
251 * recognising the \x special.
252 * returns pointer to the copied argument or NULL in case of an
253 * error (and sets err) or null argument length.
254 */
255static char *scanarg(char *s, char del)
256{
257 char c;
258
259 while ((c = *s++) != del) {
260 if (c == '\\' && *s == 'x') {
261 s++;
262 if (!isxdigit(*s++))
263 return NULL;
264 if (!isxdigit(*s++))
265 return NULL;
266 }
267 }
Al Viro7d65cf12014-12-17 05:29:16 -0500268 s[-1] ='\0';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 return s;
270}
271
Mike Frysingere6084d42014-12-10 15:52:10 -0800272static char *check_special_flags(char *sfs, Node *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273{
Mike Frysingere6084d42014-12-10 15:52:10 -0800274 char *p = sfs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 int cont = 1;
276
277 /* special flags */
278 while (cont) {
279 switch (*p) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800280 case 'P':
281 pr_debug("register: flag: P (preserve argv0)\n");
282 p++;
283 e->flags |= MISC_FMT_PRESERVE_ARGV0;
284 break;
285 case 'O':
286 pr_debug("register: flag: O (open binary)\n");
287 p++;
288 e->flags |= MISC_FMT_OPEN_BINARY;
289 break;
290 case 'C':
291 pr_debug("register: flag: C (preserve creds)\n");
292 p++;
293 /* this flags also implies the
294 open-binary flag */
295 e->flags |= (MISC_FMT_CREDENTIALS |
296 MISC_FMT_OPEN_BINARY);
297 break;
James Bottomley948b7012016-02-17 16:51:16 -0800298 case 'F':
299 pr_debug("register: flag: F: open interpreter file now\n");
300 p++;
301 e->flags |= MISC_FMT_OPEN_FILE;
302 break;
Mike Frysingere6084d42014-12-10 15:52:10 -0800303 default:
304 cont = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 }
306 }
307
308 return p;
309}
Mike Frysingere6084d42014-12-10 15:52:10 -0800310
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311/*
312 * This registers a new binary format, it recognises the syntax
313 * ':name:type:offset:magic:mask:interpreter:flags'
314 * where the ':' is the IFS, that can be chosen with the first char
315 */
316static Node *create_entry(const char __user *buffer, size_t count)
317{
318 Node *e;
319 int memsize, err;
320 char *buf, *p;
321 char del;
322
Mike Frysinger6b899c42014-12-10 15:52:08 -0800323 pr_debug("register: received %zu bytes\n", count);
324
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 /* some sanity checks */
326 err = -EINVAL;
Mike Frysingerbbaecc02014-10-13 15:52:03 -0700327 if ((count < 11) || (count > MAX_REGISTER_LENGTH))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 goto out;
329
330 err = -ENOMEM;
331 memsize = sizeof(Node) + count + 8;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800332 e = kmalloc(memsize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 if (!e)
334 goto out;
335
336 p = buf = (char *)e + sizeof(Node);
337
338 memset(e, 0, sizeof(Node));
339 if (copy_from_user(buf, buffer, count))
Mike Frysingere6084d42014-12-10 15:52:10 -0800340 goto efault;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341
342 del = *p++; /* delimeter */
343
Mike Frysinger6b899c42014-12-10 15:52:08 -0800344 pr_debug("register: delim: %#x {%c}\n", del, del);
345
346 /* Pad the buffer with the delim to simplify parsing below. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800347 memset(buf + count, del, 8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348
Mike Frysinger6b899c42014-12-10 15:52:08 -0800349 /* Parse the 'name' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 e->name = p;
351 p = strchr(p, del);
352 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800353 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 *p++ = '\0';
355 if (!e->name[0] ||
356 !strcmp(e->name, ".") ||
357 !strcmp(e->name, "..") ||
358 strchr(e->name, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800359 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800360
361 pr_debug("register: name: {%s}\n", e->name);
362
363 /* Parse the 'type' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 switch (*p++) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800365 case 'E':
366 pr_debug("register: type: E (extension)\n");
367 e->flags = 1 << Enabled;
368 break;
369 case 'M':
370 pr_debug("register: type: M (magic)\n");
371 e->flags = (1 << Enabled) | (1 << Magic);
372 break;
373 default:
Mike Frysingere6084d42014-12-10 15:52:10 -0800374 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 }
376 if (*p++ != del)
Mike Frysingere6084d42014-12-10 15:52:10 -0800377 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 if (test_bit(Magic, &e->flags)) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800380 /* Handle the 'M' (magic) format. */
381 char *s;
382
383 /* Parse the 'offset' field. */
384 s = strchr(p, del);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 if (!s)
Mike Frysingere6084d42014-12-10 15:52:10 -0800386 goto einval;
Thadeu Lima de Souza Cascardof3e72342018-06-07 17:11:01 -0700387 *s = '\0';
388 if (p != s) {
389 int r = kstrtoint(p, 10, &e->offset);
390 if (r != 0 || e->offset < 0)
391 goto einval;
392 }
393 p = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 if (*p++)
Mike Frysingere6084d42014-12-10 15:52:10 -0800395 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800396 pr_debug("register: offset: %#x\n", e->offset);
397
398 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 e->magic = p;
400 p = scanarg(p, del);
401 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800402 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500403 if (!e->magic[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800404 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800405 if (USE_DEBUG)
406 print_hex_dump_bytes(
407 KBUILD_MODNAME ": register: magic[raw]: ",
408 DUMP_PREFIX_NONE, e->magic, p - e->magic);
409
410 /* Parse the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 e->mask = p;
412 p = scanarg(p, del);
413 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800414 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500415 if (!e->mask[0]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 e->mask = NULL;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800417 pr_debug("register: mask[raw]: none\n");
418 } else if (USE_DEBUG)
419 print_hex_dump_bytes(
420 KBUILD_MODNAME ": register: mask[raw]: ",
421 DUMP_PREFIX_NONE, e->mask, p - e->mask);
422
423 /*
424 * Decode the magic & mask fields.
425 * Note: while we might have accepted embedded NUL bytes from
426 * above, the unescape helpers here will stop at the first one
427 * it encounters.
428 */
Andy Shevchenko8d82e182013-04-30 15:27:33 -0700429 e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
430 if (e->mask &&
431 string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
Mike Frysingere6084d42014-12-10 15:52:10 -0800432 goto einval;
Thadeu Lima de Souza Cascardof3e72342018-06-07 17:11:01 -0700433 if (e->size > BINPRM_BUF_SIZE ||
434 BINPRM_BUF_SIZE - e->size < e->offset)
Mike Frysingere6084d42014-12-10 15:52:10 -0800435 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800436 pr_debug("register: magic/mask length: %i\n", e->size);
437 if (USE_DEBUG) {
438 print_hex_dump_bytes(
439 KBUILD_MODNAME ": register: magic[decoded]: ",
440 DUMP_PREFIX_NONE, e->magic, e->size);
441
442 if (e->mask) {
443 int i;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800444 char *masked = kmalloc(e->size, GFP_KERNEL);
Mike Frysinger6b899c42014-12-10 15:52:08 -0800445
446 print_hex_dump_bytes(
447 KBUILD_MODNAME ": register: mask[decoded]: ",
448 DUMP_PREFIX_NONE, e->mask, e->size);
449
450 if (masked) {
451 for (i = 0; i < e->size; ++i)
452 masked[i] = e->magic[i] & e->mask[i];
453 print_hex_dump_bytes(
454 KBUILD_MODNAME ": register: magic[masked]: ",
455 DUMP_PREFIX_NONE, masked, e->size);
456
457 kfree(masked);
458 }
459 }
460 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461 } else {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800462 /* Handle the 'E' (extension) format. */
463
464 /* Skip the 'offset' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465 p = strchr(p, del);
466 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800467 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 *p++ = '\0';
Mike Frysinger6b899c42014-12-10 15:52:08 -0800469
470 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 e->magic = p;
472 p = strchr(p, del);
473 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800474 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 *p++ = '\0';
476 if (!e->magic[0] || strchr(e->magic, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800477 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800478 pr_debug("register: extension: {%s}\n", e->magic);
479
480 /* Skip the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 p = strchr(p, del);
482 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800483 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 *p++ = '\0';
485 }
Mike Frysinger6b899c42014-12-10 15:52:08 -0800486
487 /* Parse the 'interpreter' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 e->interpreter = p;
489 p = strchr(p, del);
490 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800491 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 *p++ = '\0';
493 if (!e->interpreter[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800494 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800495 pr_debug("register: interpreter: {%s}\n", e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496
Mike Frysinger6b899c42014-12-10 15:52:08 -0800497 /* Parse the 'flags' field. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800498 p = check_special_flags(p, e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 if (*p == '\n')
500 p++;
501 if (p != buf + count)
Mike Frysingere6084d42014-12-10 15:52:10 -0800502 goto einval;
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 return e;
505
506out:
507 return ERR_PTR(err);
508
Mike Frysingere6084d42014-12-10 15:52:10 -0800509efault:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510 kfree(e);
511 return ERR_PTR(-EFAULT);
Mike Frysingere6084d42014-12-10 15:52:10 -0800512einval:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 kfree(e);
514 return ERR_PTR(-EINVAL);
515}
516
517/*
518 * Set status of entry/binfmt_misc:
519 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
520 */
521static int parse_command(const char __user *buffer, size_t count)
522{
523 char s[4];
524
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 if (count > 3)
526 return -EINVAL;
527 if (copy_from_user(s, buffer, count))
528 return -EFAULT;
Arnd Bergmannde8288b2014-10-13 15:52:08 -0700529 if (!count)
530 return 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800531 if (s[count - 1] == '\n')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 count--;
533 if (count == 1 && s[0] == '0')
534 return 1;
535 if (count == 1 && s[0] == '1')
536 return 2;
537 if (count == 2 && s[0] == '-' && s[1] == '1')
538 return 3;
539 return -EINVAL;
540}
541
542/* generic stuff */
543
544static void entry_status(Node *e, char *page)
545{
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700546 char *dp = page;
547 const char *status = "disabled";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
549 if (test_bit(Enabled, &e->flags))
550 status = "enabled";
551
552 if (!VERBOSE_STATUS) {
553 sprintf(page, "%s\n", status);
554 return;
555 }
556
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700557 dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558
559 /* print the special flags */
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700560 dp += sprintf(dp, "flags: ");
Mike Frysingere6084d42014-12-10 15:52:10 -0800561 if (e->flags & MISC_FMT_PRESERVE_ARGV0)
562 *dp++ = 'P';
563 if (e->flags & MISC_FMT_OPEN_BINARY)
564 *dp++ = 'O';
565 if (e->flags & MISC_FMT_CREDENTIALS)
566 *dp++ = 'C';
James Bottomley948b7012016-02-17 16:51:16 -0800567 if (e->flags & MISC_FMT_OPEN_FILE)
568 *dp++ = 'F';
Mike Frysingere6084d42014-12-10 15:52:10 -0800569 *dp++ = '\n';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570
571 if (!test_bit(Magic, &e->flags)) {
572 sprintf(dp, "extension .%s\n", e->magic);
573 } else {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700574 dp += sprintf(dp, "offset %i\nmagic ", e->offset);
575 dp = bin2hex(dp, e->magic, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 if (e->mask) {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700577 dp += sprintf(dp, "\nmask ");
578 dp = bin2hex(dp, e->mask, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 }
580 *dp++ = '\n';
581 *dp = '\0';
582 }
583}
584
585static struct inode *bm_get_inode(struct super_block *sb, int mode)
586{
Mike Frysingere6084d42014-12-10 15:52:10 -0800587 struct inode *inode = new_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588
589 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -0400590 inode->i_ino = get_next_ino();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 inode->i_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 inode->i_atime = inode->i_mtime = inode->i_ctime =
Deepa Dinamanic2050a42016-09-14 07:48:06 -0700593 current_time(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 }
595 return inode;
596}
597
Al Virob57922d2010-06-07 14:34:48 -0400598static void bm_evict_inode(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599{
Jan Karadbd57682012-05-03 14:48:02 +0200600 clear_inode(inode);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700601 kfree(inode->i_private);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602}
603
604static void kill_node(Node *e)
605{
606 struct dentry *dentry;
607
608 write_lock(&entries_lock);
609 dentry = e->dentry;
610 if (dentry) {
611 list_del_init(&e->list);
612 e->dentry = NULL;
613 }
614 write_unlock(&entries_lock);
615
James Bottomley948b7012016-02-17 16:51:16 -0800616 if ((e->flags & MISC_FMT_OPEN_FILE) && e->interp_file) {
617 filp_close(e->interp_file, NULL);
618 e->interp_file = NULL;
619 }
620
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 if (dentry) {
David Howells75c3cfa2015-03-17 22:26:12 +0000622 drop_nlink(d_inode(dentry));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 d_drop(dentry);
624 dput(dentry);
625 simple_release_fs(&bm_mnt, &entry_count);
626 }
627}
628
629/* /<entry> */
630
631static ssize_t
Mike Frysingere6084d42014-12-10 15:52:10 -0800632bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633{
Al Viro496ad9a2013-01-23 17:07:38 -0500634 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 ssize_t res;
636 char *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
Mike Frysingere6084d42014-12-10 15:52:10 -0800638 page = (char *) __get_free_page(GFP_KERNEL);
639 if (!page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 return -ENOMEM;
641
642 entry_status(e, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643
Akinobu Mita6e2c10a2008-07-23 21:29:15 -0700644 res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
645
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646 free_page((unsigned long) page);
647 return res;
648}
649
650static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
651 size_t count, loff_t *ppos)
652{
653 struct dentry *root;
Al Viro496ad9a2013-01-23 17:07:38 -0500654 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 int res = parse_command(buffer, count);
656
657 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800658 case 1:
659 /* Disable this handler. */
660 clear_bit(Enabled, &e->flags);
661 break;
662 case 2:
663 /* Enable this handler. */
664 set_bit(Enabled, &e->flags);
665 break;
666 case 3:
667 /* Delete this handler. */
Al Viroea7d4c02016-05-29 19:14:03 -0400668 root = file_inode(file)->i_sb->s_root;
Al Viro59551022016-01-22 15:40:57 -0500669 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670
Mike Frysingere6084d42014-12-10 15:52:10 -0800671 kill_node(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672
Al Viro59551022016-01-22 15:40:57 -0500673 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800674 break;
675 default:
676 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800678
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 return count;
680}
681
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800682static const struct file_operations bm_entry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 .read = bm_entry_read,
684 .write = bm_entry_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200685 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686};
687
688/* /register */
689
690static ssize_t bm_register_write(struct file *file, const char __user *buffer,
691 size_t count, loff_t *ppos)
692{
693 Node *e;
694 struct inode *inode;
Al Viroea7d4c02016-05-29 19:14:03 -0400695 struct super_block *sb = file_inode(file)->i_sb;
696 struct dentry *root = sb->s_root, *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 int err = 0;
Lior Ribak467a50d2021-03-12 21:07:41 -0800698 struct file *f = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699
700 e = create_entry(buffer, count);
701
702 if (IS_ERR(e))
703 return PTR_ERR(e);
704
Lior Ribak467a50d2021-03-12 21:07:41 -0800705 if (e->flags & MISC_FMT_OPEN_FILE) {
706 f = open_exec(e->interpreter);
707 if (IS_ERR(f)) {
708 pr_notice("register: failed to install interpreter file %s\n",
709 e->interpreter);
710 kfree(e);
711 return PTR_ERR(f);
712 }
713 e->interp_file = f;
714 }
715
Al Viro59551022016-01-22 15:40:57 -0500716 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 dentry = lookup_one_len(e->name, root, strlen(e->name));
718 err = PTR_ERR(dentry);
719 if (IS_ERR(dentry))
720 goto out;
721
722 err = -EEXIST;
David Howells75c3cfa2015-03-17 22:26:12 +0000723 if (d_really_is_positive(dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 goto out2;
725
726 inode = bm_get_inode(sb, S_IFREG | 0644);
727
728 err = -ENOMEM;
729 if (!inode)
730 goto out2;
731
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400732 err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 if (err) {
734 iput(inode);
735 inode = NULL;
736 goto out2;
737 }
738
739 e->dentry = dget(dentry);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700740 inode->i_private = e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 inode->i_fop = &bm_entry_operations;
742
743 d_instantiate(dentry, inode);
744 write_lock(&entries_lock);
745 list_add(&e->list, &entries);
746 write_unlock(&entries_lock);
747
748 err = 0;
749out2:
750 dput(dentry);
751out:
Al Viro59551022016-01-22 15:40:57 -0500752 inode_unlock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753
754 if (err) {
Lior Ribak467a50d2021-03-12 21:07:41 -0800755 if (f)
756 filp_close(f, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 kfree(e);
James Bottomley948b7012016-02-17 16:51:16 -0800758 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 }
760 return count;
761}
762
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800763static const struct file_operations bm_register_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 .write = bm_register_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200765 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766};
767
768/* /status */
769
770static ssize_t
771bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
772{
Qinghuang Feng87113e802009-01-06 14:41:38 -0800773 char *s = enabled ? "enabled\n" : "disabled\n";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
Akinobu Mita92f4c702007-05-09 02:33:32 -0700775 return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776}
777
Mike Frysingere6084d42014-12-10 15:52:10 -0800778static ssize_t bm_status_write(struct file *file, const char __user *buffer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779 size_t count, loff_t *ppos)
780{
781 int res = parse_command(buffer, count);
782 struct dentry *root;
783
784 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800785 case 1:
786 /* Disable all handlers. */
787 enabled = 0;
788 break;
789 case 2:
790 /* Enable all handlers. */
791 enabled = 1;
792 break;
793 case 3:
794 /* Delete all handlers. */
Al Viroea7d4c02016-05-29 19:14:03 -0400795 root = file_inode(file)->i_sb->s_root;
Al Viro59551022016-01-22 15:40:57 -0500796 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797
Mike Frysingere6084d42014-12-10 15:52:10 -0800798 while (!list_empty(&entries))
799 kill_node(list_entry(entries.next, Node, list));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
Al Viro59551022016-01-22 15:40:57 -0500801 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800802 break;
803 default:
804 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800806
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 return count;
808}
809
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800810static const struct file_operations bm_status_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 .read = bm_status_read,
812 .write = bm_status_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200813 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814};
815
816/* Superblock handling */
817
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800818static const struct super_operations s_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 .statfs = simple_statfs,
Al Virob57922d2010-06-07 14:34:48 -0400820 .evict_inode = bm_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821};
822
Mike Frysingere6084d42014-12-10 15:52:10 -0800823static int bm_fill_super(struct super_block *sb, void *data, int silent)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824{
Mike Frysingere6084d42014-12-10 15:52:10 -0800825 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 static struct tree_descr bm_files[] = {
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700827 [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
828 [3] = {"register", &bm_register_operations, S_IWUSR},
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 /* last one */ {""}
830 };
Mike Frysingere6084d42014-12-10 15:52:10 -0800831
832 err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 if (!err)
834 sb->s_op = &s_ops;
835 return err;
836}
837
Al Virofc14f2f2010-07-25 01:48:30 +0400838static struct dentry *bm_mount(struct file_system_type *fs_type,
839 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840{
Al Virofc14f2f2010-07-25 01:48:30 +0400841 return mount_single(fs_type, flags, data, bm_fill_super);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842}
843
844static struct linux_binfmt misc_format = {
845 .module = THIS_MODULE,
846 .load_binary = load_misc_binary,
847};
848
849static struct file_system_type bm_fs_type = {
850 .owner = THIS_MODULE,
851 .name = "binfmt_misc",
Al Virofc14f2f2010-07-25 01:48:30 +0400852 .mount = bm_mount,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 .kill_sb = kill_litter_super,
854};
Eric W. Biederman7f78e032013-03-02 19:39:14 -0800855MODULE_ALIAS_FS("binfmt_misc");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856
857static int __init init_misc_binfmt(void)
858{
859 int err = register_filesystem(&bm_fs_type);
Al Viro8fc3dc52012-03-17 03:05:16 -0400860 if (!err)
861 insert_binfmt(&misc_format);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 return err;
863}
864
865static void __exit exit_misc_binfmt(void)
866{
867 unregister_binfmt(&misc_format);
868 unregister_filesystem(&bm_fs_type);
869}
870
871core_initcall(init_misc_binfmt);
872module_exit(exit_misc_binfmt);
873MODULE_LICENSE("GPL");