blob: ad2866f28f0cfa82002a5eed1e9e166b11d1e777 [file] [log] [blame]
Thomas Gleixner09c434b2019-05-19 13:08:20 +01001// SPDX-License-Identifier: GPL-2.0-only
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
Mike Frysingere6084d42014-12-10 15:52:10 -08003 * binfmt_misc.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 *
Mike Frysingere6084d42014-12-10 15:52:10 -08005 * Copyright (C) 1997 Richard Günther
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
Mike Frysingere6084d42014-12-10 15:52:10 -08007 * binfmt_misc detects binaries via a magic or filename extension and invokes
Mauro Carvalho Chehab34962fb2018-05-08 15:14:57 -03008 * a specified wrapper. See Documentation/admin-guide/binfmt-misc.rst for more details.
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 */
10
Mike Frysinger6b899c42014-12-10 15:52:08 -080011#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -070013#include <linux/kernel.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/module.h>
15#include <linux/init.h>
Ingo Molnar589ee622017-02-04 00:16:44 +010016#include <linux/sched/mm.h>
Muthu Kumarb502bd12012-03-23 15:01:50 -070017#include <linux/magic.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/binfmts.h>
19#include <linux/slab.h>
20#include <linux/ctype.h>
Andy Shevchenko8d82e182013-04-30 15:27:33 -070021#include <linux/string_helpers.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/file.h>
23#include <linux/pagemap.h>
24#include <linux/namei.h>
25#include <linux/mount.h>
David Howellsbc99a662019-03-25 16:38:28 +000026#include <linux/fs_context.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/syscalls.h>
Akinobu Mita6e2c10a2008-07-23 21:29:15 -070028#include <linux/fs.h>
Mike Frysinger6b899c42014-12-10 15:52:08 -080029#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
James Bottomley948b7012016-02-17 16:51:16 -080031#include "internal.h"
32
Mike Frysinger6b899c42014-12-10 15:52:08 -080033#ifdef DEBUG
34# define USE_DEBUG 1
35#else
36# define USE_DEBUG 0
37#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
39enum {
40 VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
41};
42
43static LIST_HEAD(entries);
44static int enabled = 1;
45
46enum {Enabled, Magic};
Mike Frysingere6084d42014-12-10 15:52:10 -080047#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
48#define MISC_FMT_OPEN_BINARY (1 << 30)
49#define MISC_FMT_CREDENTIALS (1 << 29)
James Bottomley948b7012016-02-17 16:51:16 -080050#define MISC_FMT_OPEN_FILE (1 << 28)
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52typedef 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 */
Oleg Nesterov50097f72017-10-03 16:15:58 -070059 const char *interpreter; /* filename of interpreter */
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 char *name;
61 struct dentry *dentry;
James Bottomley948b7012016-02-17 16:51:16 -080062 struct file *interp_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -070063} Node;
64
65static DEFINE_RWLOCK(entries_lock);
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -040066static struct file_system_type bm_fs_type;
Linus Torvalds1da177e2005-04-16 15:20:36 -070067static struct vfsmount *bm_mnt;
68static int entry_count;
69
Mike Frysingerbbaecc02014-10-13 15:52:03 -070070/*
71 * Max length of the register string. Determined by:
72 * - 7 delimiters
73 * - name: ~50 bytes
74 * - type: 1 byte
75 * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
76 * - magic: 128 bytes (512 in escaped form)
77 * - mask: 128 bytes (512 in escaped form)
78 * - interp: ~50 bytes
79 * - flags: 5 bytes
80 * Round that up a bit, and then back off to hold the internal data
81 * (like struct Node).
82 */
83#define MAX_REGISTER_LENGTH 1920
84
85/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 * Check if we support the binfmt
87 * if we do, return the node, else NULL
88 * locking is done in load_misc_binary
89 */
90static Node *check_file(struct linux_binprm *bprm)
91{
92 char *p = strrchr(bprm->interp, '.');
93 struct list_head *l;
94
Mike Frysinger6b899c42014-12-10 15:52:08 -080095 /* Walk all the registered handlers. */
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 list_for_each(l, &entries) {
97 Node *e = list_entry(l, Node, list);
98 char *s;
99 int j;
100
Mike Frysinger6b899c42014-12-10 15:52:08 -0800101 /* Make sure this one is currently enabled. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 if (!test_bit(Enabled, &e->flags))
103 continue;
104
Mike Frysinger6b899c42014-12-10 15:52:08 -0800105 /* Do matching based on extension if applicable. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 if (!test_bit(Magic, &e->flags)) {
107 if (p && !strcmp(e->magic, p + 1))
108 return e;
109 continue;
110 }
111
Mike Frysinger6b899c42014-12-10 15:52:08 -0800112 /* Do matching based on magic & mask. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 s = bprm->buf + e->offset;
114 if (e->mask) {
115 for (j = 0; j < e->size; j++)
116 if ((*s++ ^ e->magic[j]) & e->mask[j])
117 break;
118 } else {
119 for (j = 0; j < e->size; j++)
120 if ((*s++ ^ e->magic[j]))
121 break;
122 }
123 if (j == e->size)
124 return e;
125 }
126 return NULL;
127}
128
129/*
130 * the loader itself
131 */
Al Viro71613c32012-10-20 22:00:48 -0400132static int load_misc_binary(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133{
134 Node *fmt;
Mike Frysingere6084d42014-12-10 15:52:10 -0800135 struct file *interp_file = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137
138 retval = -ENOEXEC;
139 if (!enabled)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700140 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
142 /* to keep locking time low, we copy the interpreter string */
143 read_lock(&entries_lock);
144 fmt = check_file(bprm);
Oleg Nesterov50097f72017-10-03 16:15:58 -0700145 if (fmt)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700146 dget(fmt->dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 read_unlock(&entries_lock);
148 if (!fmt)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700149 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150
David Drysdale51f39a12014-12-12 16:57:29 -0800151 /* Need to be able to load the file after exec */
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700152 retval = -ENOENT;
David Drysdale51f39a12014-12-12 16:57:29 -0800153 if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700154 goto ret;
David Drysdale51f39a12014-12-12 16:57:29 -0800155
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) {
Eric W. Biedermanb8a61c92020-05-14 15:17:40 -0500163 /* Pass the open binary to the interpreter */
164 bprm->have_execfd = 1;
165 bprm->executable = bprm->file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
167 allow_write_access(bprm->file);
168 bprm->file = NULL;
Mike Frysingere6084d42014-12-10 15:52:10 -0800169 } else {
170 allow_write_access(bprm->file);
171 fput(bprm->file);
172 bprm->file = NULL;
173 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 /* make argv[1] be the path to the binary */
Mike Frysingere6084d42014-12-10 15:52:10 -0800175 retval = copy_strings_kernel(1, &bprm->interp, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 if (retval < 0)
Eric W. Biedermanb8a61c92020-05-14 15:17:40 -0500177 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 bprm->argc++;
179
180 /* add the interp as argv[0] */
Oleg Nesterov50097f72017-10-03 16:15:58 -0700181 retval = copy_strings_kernel(1, &fmt->interpreter, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 if (retval < 0)
Eric W. Biedermanb8a61c92020-05-14 15:17:40 -0500183 goto ret;
Mike Frysingere6084d42014-12-10 15:52:10 -0800184 bprm->argc++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
Kees Cookb66c5982012-12-20 15:05:16 -0800186 /* Update interp in case binfmt_script needs it. */
Oleg Nesterov50097f72017-10-03 16:15:58 -0700187 retval = bprm_change_interp(fmt->interpreter, bprm);
Kees Cookb66c5982012-12-20 15:05:16 -0800188 if (retval < 0)
Eric W. Biedermanb8a61c92020-05-14 15:17:40 -0500189 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190
Oleg Nesteroveb23aa02017-10-03 16:15:51 -0700191 if (fmt->flags & MISC_FMT_OPEN_FILE) {
Al Viro19f391e2018-06-08 11:19:32 -0400192 interp_file = file_clone_open(fmt->interp_file);
James Bottomley948b7012016-02-17 16:51:16 -0800193 if (!IS_ERR(interp_file))
194 deny_write_access(interp_file);
195 } else {
Oleg Nesterov50097f72017-10-03 16:15:58 -0700196 interp_file = open_exec(fmt->interpreter);
James Bottomley948b7012016-02-17 16:51:16 -0800197 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800198 retval = PTR_ERR(interp_file);
199 if (IS_ERR(interp_file))
Eric W. Biedermanb8a61c92020-05-14 15:17:40 -0500200 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
202 bprm->file = interp_file;
Eric W. Biedermana16b33572020-05-16 06:02:54 -0500203 if (fmt->flags & MISC_FMT_CREDENTIALS)
204 bprm->preserve_creds = 1;
Christoph Hellwigbdd1d2d2017-09-01 17:39:13 +0200205
Al Viro3c456bf2012-10-20 21:53:31 -0400206 retval = search_binary_handler(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 if (retval < 0)
Eric W. Biedermanb8a61c92020-05-14 15:17:40 -0500208 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
Mike Frysingere6084d42014-12-10 15:52:10 -0800210ret:
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700211 dput(fmt->dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213}
214
215/* Command parsers */
216
217/*
218 * parses and copies one argument enclosed in del from *sp to *dp,
219 * recognising the \x special.
220 * returns pointer to the copied argument or NULL in case of an
221 * error (and sets err) or null argument length.
222 */
223static char *scanarg(char *s, char del)
224{
225 char c;
226
227 while ((c = *s++) != del) {
228 if (c == '\\' && *s == 'x') {
229 s++;
230 if (!isxdigit(*s++))
231 return NULL;
232 if (!isxdigit(*s++))
233 return NULL;
234 }
235 }
Al Viro7d65cf12014-12-17 05:29:16 -0500236 s[-1] ='\0';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 return s;
238}
239
Mike Frysingere6084d42014-12-10 15:52:10 -0800240static char *check_special_flags(char *sfs, Node *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241{
Mike Frysingere6084d42014-12-10 15:52:10 -0800242 char *p = sfs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 int cont = 1;
244
245 /* special flags */
246 while (cont) {
247 switch (*p) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800248 case 'P':
249 pr_debug("register: flag: P (preserve argv0)\n");
250 p++;
251 e->flags |= MISC_FMT_PRESERVE_ARGV0;
252 break;
253 case 'O':
254 pr_debug("register: flag: O (open binary)\n");
255 p++;
256 e->flags |= MISC_FMT_OPEN_BINARY;
257 break;
258 case 'C':
259 pr_debug("register: flag: C (preserve creds)\n");
260 p++;
261 /* this flags also implies the
262 open-binary flag */
263 e->flags |= (MISC_FMT_CREDENTIALS |
264 MISC_FMT_OPEN_BINARY);
265 break;
James Bottomley948b7012016-02-17 16:51:16 -0800266 case 'F':
267 pr_debug("register: flag: F: open interpreter file now\n");
268 p++;
269 e->flags |= MISC_FMT_OPEN_FILE;
270 break;
Mike Frysingere6084d42014-12-10 15:52:10 -0800271 default:
272 cont = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 }
274 }
275
276 return p;
277}
Mike Frysingere6084d42014-12-10 15:52:10 -0800278
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279/*
280 * This registers a new binary format, it recognises the syntax
281 * ':name:type:offset:magic:mask:interpreter:flags'
282 * where the ':' is the IFS, that can be chosen with the first char
283 */
284static Node *create_entry(const char __user *buffer, size_t count)
285{
286 Node *e;
287 int memsize, err;
288 char *buf, *p;
289 char del;
290
Mike Frysinger6b899c42014-12-10 15:52:08 -0800291 pr_debug("register: received %zu bytes\n", count);
292
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 /* some sanity checks */
294 err = -EINVAL;
Mike Frysingerbbaecc02014-10-13 15:52:03 -0700295 if ((count < 11) || (count > MAX_REGISTER_LENGTH))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 goto out;
297
298 err = -ENOMEM;
299 memsize = sizeof(Node) + count + 8;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800300 e = kmalloc(memsize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 if (!e)
302 goto out;
303
304 p = buf = (char *)e + sizeof(Node);
305
306 memset(e, 0, sizeof(Node));
307 if (copy_from_user(buf, buffer, count))
Mike Frysingere6084d42014-12-10 15:52:10 -0800308 goto efault;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309
310 del = *p++; /* delimeter */
311
Mike Frysinger6b899c42014-12-10 15:52:08 -0800312 pr_debug("register: delim: %#x {%c}\n", del, del);
313
314 /* Pad the buffer with the delim to simplify parsing below. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800315 memset(buf + count, del, 8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
Mike Frysinger6b899c42014-12-10 15:52:08 -0800317 /* Parse the 'name' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 e->name = p;
319 p = strchr(p, del);
320 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800321 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 *p++ = '\0';
323 if (!e->name[0] ||
324 !strcmp(e->name, ".") ||
325 !strcmp(e->name, "..") ||
326 strchr(e->name, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800327 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800328
329 pr_debug("register: name: {%s}\n", e->name);
330
331 /* Parse the 'type' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 switch (*p++) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800333 case 'E':
334 pr_debug("register: type: E (extension)\n");
335 e->flags = 1 << Enabled;
336 break;
337 case 'M':
338 pr_debug("register: type: M (magic)\n");
339 e->flags = (1 << Enabled) | (1 << Magic);
340 break;
341 default:
Mike Frysingere6084d42014-12-10 15:52:10 -0800342 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 }
344 if (*p++ != del)
Mike Frysingere6084d42014-12-10 15:52:10 -0800345 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800346
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 if (test_bit(Magic, &e->flags)) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800348 /* Handle the 'M' (magic) format. */
349 char *s;
350
351 /* Parse the 'offset' field. */
352 s = strchr(p, del);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 if (!s)
Mike Frysingere6084d42014-12-10 15:52:10 -0800354 goto einval;
Thadeu Lima de Souza Cascardo5cc41e02018-06-07 17:11:01 -0700355 *s = '\0';
356 if (p != s) {
357 int r = kstrtoint(p, 10, &e->offset);
358 if (r != 0 || e->offset < 0)
359 goto einval;
360 }
361 p = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 if (*p++)
Mike Frysingere6084d42014-12-10 15:52:10 -0800363 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800364 pr_debug("register: offset: %#x\n", e->offset);
365
366 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 e->magic = p;
368 p = scanarg(p, del);
369 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800370 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500371 if (!e->magic[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800372 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800373 if (USE_DEBUG)
374 print_hex_dump_bytes(
375 KBUILD_MODNAME ": register: magic[raw]: ",
376 DUMP_PREFIX_NONE, e->magic, p - e->magic);
377
378 /* Parse the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 e->mask = 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->mask[0]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 e->mask = NULL;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800385 pr_debug("register: mask[raw]: none\n");
386 } else if (USE_DEBUG)
387 print_hex_dump_bytes(
388 KBUILD_MODNAME ": register: mask[raw]: ",
389 DUMP_PREFIX_NONE, e->mask, p - e->mask);
390
391 /*
392 * Decode the magic & mask fields.
393 * Note: while we might have accepted embedded NUL bytes from
394 * above, the unescape helpers here will stop at the first one
395 * it encounters.
396 */
Andy Shevchenko8d82e182013-04-30 15:27:33 -0700397 e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
398 if (e->mask &&
399 string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
Mike Frysingere6084d42014-12-10 15:52:10 -0800400 goto einval;
Thadeu Lima de Souza Cascardo5cc41e02018-06-07 17:11:01 -0700401 if (e->size > BINPRM_BUF_SIZE ||
402 BINPRM_BUF_SIZE - e->size < e->offset)
Mike Frysingere6084d42014-12-10 15:52:10 -0800403 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800404 pr_debug("register: magic/mask length: %i\n", e->size);
405 if (USE_DEBUG) {
406 print_hex_dump_bytes(
407 KBUILD_MODNAME ": register: magic[decoded]: ",
408 DUMP_PREFIX_NONE, e->magic, e->size);
409
410 if (e->mask) {
411 int i;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800412 char *masked = kmalloc(e->size, GFP_KERNEL);
Mike Frysinger6b899c42014-12-10 15:52:08 -0800413
414 print_hex_dump_bytes(
415 KBUILD_MODNAME ": register: mask[decoded]: ",
416 DUMP_PREFIX_NONE, e->mask, e->size);
417
418 if (masked) {
419 for (i = 0; i < e->size; ++i)
420 masked[i] = e->magic[i] & e->mask[i];
421 print_hex_dump_bytes(
422 KBUILD_MODNAME ": register: magic[masked]: ",
423 DUMP_PREFIX_NONE, masked, e->size);
424
425 kfree(masked);
426 }
427 }
428 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 } else {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800430 /* Handle the 'E' (extension) format. */
431
432 /* Skip the 'offset' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 p = strchr(p, del);
434 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800435 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 *p++ = '\0';
Mike Frysinger6b899c42014-12-10 15:52:08 -0800437
438 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439 e->magic = p;
440 p = strchr(p, del);
441 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800442 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 *p++ = '\0';
444 if (!e->magic[0] || strchr(e->magic, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800445 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800446 pr_debug("register: extension: {%s}\n", e->magic);
447
448 /* Skip the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449 p = strchr(p, del);
450 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800451 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 *p++ = '\0';
453 }
Mike Frysinger6b899c42014-12-10 15:52:08 -0800454
455 /* Parse the 'interpreter' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 e->interpreter = p;
457 p = strchr(p, del);
458 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800459 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 *p++ = '\0';
461 if (!e->interpreter[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800462 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800463 pr_debug("register: interpreter: {%s}\n", e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464
Mike Frysinger6b899c42014-12-10 15:52:08 -0800465 /* Parse the 'flags' field. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800466 p = check_special_flags(p, e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 if (*p == '\n')
468 p++;
469 if (p != buf + count)
Mike Frysingere6084d42014-12-10 15:52:10 -0800470 goto einval;
471
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 return e;
473
474out:
475 return ERR_PTR(err);
476
Mike Frysingere6084d42014-12-10 15:52:10 -0800477efault:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 kfree(e);
479 return ERR_PTR(-EFAULT);
Mike Frysingere6084d42014-12-10 15:52:10 -0800480einval:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 kfree(e);
482 return ERR_PTR(-EINVAL);
483}
484
485/*
486 * Set status of entry/binfmt_misc:
487 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
488 */
489static int parse_command(const char __user *buffer, size_t count)
490{
491 char s[4];
492
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 if (count > 3)
494 return -EINVAL;
495 if (copy_from_user(s, buffer, count))
496 return -EFAULT;
Arnd Bergmannde8288b2014-10-13 15:52:08 -0700497 if (!count)
498 return 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800499 if (s[count - 1] == '\n')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 count--;
501 if (count == 1 && s[0] == '0')
502 return 1;
503 if (count == 1 && s[0] == '1')
504 return 2;
505 if (count == 2 && s[0] == '-' && s[1] == '1')
506 return 3;
507 return -EINVAL;
508}
509
510/* generic stuff */
511
512static void entry_status(Node *e, char *page)
513{
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700514 char *dp = page;
515 const char *status = "disabled";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
517 if (test_bit(Enabled, &e->flags))
518 status = "enabled";
519
520 if (!VERBOSE_STATUS) {
521 sprintf(page, "%s\n", status);
522 return;
523 }
524
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700525 dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526
527 /* print the special flags */
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700528 dp += sprintf(dp, "flags: ");
Mike Frysingere6084d42014-12-10 15:52:10 -0800529 if (e->flags & MISC_FMT_PRESERVE_ARGV0)
530 *dp++ = 'P';
531 if (e->flags & MISC_FMT_OPEN_BINARY)
532 *dp++ = 'O';
533 if (e->flags & MISC_FMT_CREDENTIALS)
534 *dp++ = 'C';
James Bottomley948b7012016-02-17 16:51:16 -0800535 if (e->flags & MISC_FMT_OPEN_FILE)
536 *dp++ = 'F';
Mike Frysingere6084d42014-12-10 15:52:10 -0800537 *dp++ = '\n';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538
539 if (!test_bit(Magic, &e->flags)) {
540 sprintf(dp, "extension .%s\n", e->magic);
541 } else {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700542 dp += sprintf(dp, "offset %i\nmagic ", e->offset);
543 dp = bin2hex(dp, e->magic, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544 if (e->mask) {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700545 dp += sprintf(dp, "\nmask ");
546 dp = bin2hex(dp, e->mask, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 }
548 *dp++ = '\n';
549 *dp = '\0';
550 }
551}
552
553static struct inode *bm_get_inode(struct super_block *sb, int mode)
554{
Mike Frysingere6084d42014-12-10 15:52:10 -0800555 struct inode *inode = new_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556
557 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -0400558 inode->i_ino = get_next_ino();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 inode->i_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 inode->i_atime = inode->i_mtime = inode->i_ctime =
Deepa Dinamanic2050a42016-09-14 07:48:06 -0700561 current_time(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 }
563 return inode;
564}
565
Al Virob57922d2010-06-07 14:34:48 -0400566static void bm_evict_inode(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567{
Oleg Nesterov83f91822017-10-03 16:15:48 -0700568 Node *e = inode->i_private;
569
Eryu Guan7e866002017-10-13 15:58:18 -0700570 if (e && e->flags & MISC_FMT_OPEN_FILE)
Oleg Nesterov83f91822017-10-03 16:15:48 -0700571 filp_close(e->interp_file, NULL);
572
Jan Karadbd57682012-05-03 14:48:02 +0200573 clear_inode(inode);
Oleg Nesterov83f91822017-10-03 16:15:48 -0700574 kfree(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575}
576
577static void kill_node(Node *e)
578{
579 struct dentry *dentry;
580
581 write_lock(&entries_lock);
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700582 list_del_init(&e->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583 write_unlock(&entries_lock);
584
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700585 dentry = e->dentry;
586 drop_nlink(d_inode(dentry));
587 d_drop(dentry);
588 dput(dentry);
589 simple_release_fs(&bm_mnt, &entry_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590}
591
592/* /<entry> */
593
594static ssize_t
Mike Frysingere6084d42014-12-10 15:52:10 -0800595bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596{
Al Viro496ad9a2013-01-23 17:07:38 -0500597 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 ssize_t res;
599 char *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600
Mike Frysingere6084d42014-12-10 15:52:10 -0800601 page = (char *) __get_free_page(GFP_KERNEL);
602 if (!page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 return -ENOMEM;
604
605 entry_status(e, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606
Akinobu Mita6e2c10a2008-07-23 21:29:15 -0700607 res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
608
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 free_page((unsigned long) page);
610 return res;
611}
612
613static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
614 size_t count, loff_t *ppos)
615{
616 struct dentry *root;
Al Viro496ad9a2013-01-23 17:07:38 -0500617 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 int res = parse_command(buffer, count);
619
620 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800621 case 1:
622 /* Disable this handler. */
623 clear_bit(Enabled, &e->flags);
624 break;
625 case 2:
626 /* Enable this handler. */
627 set_bit(Enabled, &e->flags);
628 break;
629 case 3:
630 /* Delete this handler. */
Al Viroea7d4c02016-05-29 19:14:03 -0400631 root = file_inode(file)->i_sb->s_root;
Al Viro59551022016-01-22 15:40:57 -0500632 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700634 if (!list_empty(&e->list))
635 kill_node(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
Al Viro59551022016-01-22 15:40:57 -0500637 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800638 break;
639 default:
640 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800642
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 return count;
644}
645
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800646static const struct file_operations bm_entry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 .read = bm_entry_read,
648 .write = bm_entry_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200649 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650};
651
652/* /register */
653
654static ssize_t bm_register_write(struct file *file, const char __user *buffer,
655 size_t count, loff_t *ppos)
656{
657 Node *e;
658 struct inode *inode;
Al Viroea7d4c02016-05-29 19:14:03 -0400659 struct super_block *sb = file_inode(file)->i_sb;
660 struct dentry *root = sb->s_root, *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 int err = 0;
662
663 e = create_entry(buffer, count);
664
665 if (IS_ERR(e))
666 return PTR_ERR(e);
667
Al Viro59551022016-01-22 15:40:57 -0500668 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 dentry = lookup_one_len(e->name, root, strlen(e->name));
670 err = PTR_ERR(dentry);
671 if (IS_ERR(dentry))
672 goto out;
673
674 err = -EEXIST;
David Howells75c3cfa2015-03-17 22:26:12 +0000675 if (d_really_is_positive(dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 goto out2;
677
678 inode = bm_get_inode(sb, S_IFREG | 0644);
679
680 err = -ENOMEM;
681 if (!inode)
682 goto out2;
683
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400684 err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 if (err) {
686 iput(inode);
687 inode = NULL;
688 goto out2;
689 }
690
James Bottomley948b7012016-02-17 16:51:16 -0800691 if (e->flags & MISC_FMT_OPEN_FILE) {
692 struct file *f;
693
694 f = open_exec(e->interpreter);
695 if (IS_ERR(f)) {
696 err = PTR_ERR(f);
697 pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
698 simple_release_fs(&bm_mnt, &entry_count);
699 iput(inode);
700 inode = NULL;
701 goto out2;
702 }
703 e->interp_file = f;
704 }
705
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706 e->dentry = dget(dentry);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700707 inode->i_private = e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 inode->i_fop = &bm_entry_operations;
709
710 d_instantiate(dentry, inode);
711 write_lock(&entries_lock);
712 list_add(&e->list, &entries);
713 write_unlock(&entries_lock);
714
715 err = 0;
716out2:
717 dput(dentry);
718out:
Al Viro59551022016-01-22 15:40:57 -0500719 inode_unlock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720
721 if (err) {
722 kfree(e);
James Bottomley948b7012016-02-17 16:51:16 -0800723 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 }
725 return count;
726}
727
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800728static const struct file_operations bm_register_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 .write = bm_register_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200730 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731};
732
733/* /status */
734
735static ssize_t
736bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
737{
Qinghuang Feng87113e82009-01-06 14:41:38 -0800738 char *s = enabled ? "enabled\n" : "disabled\n";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739
Akinobu Mita92f4c702007-05-09 02:33:32 -0700740 return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741}
742
Mike Frysingere6084d42014-12-10 15:52:10 -0800743static ssize_t bm_status_write(struct file *file, const char __user *buffer,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 size_t count, loff_t *ppos)
745{
746 int res = parse_command(buffer, count);
747 struct dentry *root;
748
749 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800750 case 1:
751 /* Disable all handlers. */
752 enabled = 0;
753 break;
754 case 2:
755 /* Enable all handlers. */
756 enabled = 1;
757 break;
758 case 3:
759 /* Delete all handlers. */
Al Viroea7d4c02016-05-29 19:14:03 -0400760 root = file_inode(file)->i_sb->s_root;
Al Viro59551022016-01-22 15:40:57 -0500761 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762
Mike Frysingere6084d42014-12-10 15:52:10 -0800763 while (!list_empty(&entries))
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700764 kill_node(list_first_entry(&entries, Node, list));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765
Al Viro59551022016-01-22 15:40:57 -0500766 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800767 break;
768 default:
769 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800771
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772 return count;
773}
774
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800775static const struct file_operations bm_status_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 .read = bm_status_read,
777 .write = bm_status_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200778 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779};
780
781/* Superblock handling */
782
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800783static const struct super_operations s_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 .statfs = simple_statfs,
Al Virob57922d2010-06-07 14:34:48 -0400785 .evict_inode = bm_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786};
787
David Howellsbc99a662019-03-25 16:38:28 +0000788static int bm_fill_super(struct super_block *sb, struct fs_context *fc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789{
Mike Frysingere6084d42014-12-10 15:52:10 -0800790 int err;
Eric Biggerscda37122017-03-25 21:15:37 -0700791 static const struct tree_descr bm_files[] = {
Jeff Layton1a1c9bb2007-05-08 00:32:31 -0700792 [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
793 [3] = {"register", &bm_register_operations, S_IWUSR},
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 /* last one */ {""}
795 };
Mike Frysingere6084d42014-12-10 15:52:10 -0800796
797 err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 if (!err)
799 sb->s_op = &s_ops;
800 return err;
801}
802
David Howellsbc99a662019-03-25 16:38:28 +0000803static int bm_get_tree(struct fs_context *fc)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804{
David Howellsbc99a662019-03-25 16:38:28 +0000805 return get_tree_single(fc, bm_fill_super);
806}
807
808static const struct fs_context_operations bm_context_ops = {
809 .get_tree = bm_get_tree,
810};
811
812static int bm_init_fs_context(struct fs_context *fc)
813{
814 fc->ops = &bm_context_ops;
815 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816}
817
818static struct linux_binfmt misc_format = {
819 .module = THIS_MODULE,
820 .load_binary = load_misc_binary,
821};
822
823static struct file_system_type bm_fs_type = {
824 .owner = THIS_MODULE,
825 .name = "binfmt_misc",
David Howellsbc99a662019-03-25 16:38:28 +0000826 .init_fs_context = bm_init_fs_context,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700827 .kill_sb = kill_litter_super,
828};
Eric W. Biederman7f78e032013-03-02 19:39:14 -0800829MODULE_ALIAS_FS("binfmt_misc");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830
831static int __init init_misc_binfmt(void)
832{
833 int err = register_filesystem(&bm_fs_type);
Al Viro8fc3dc52012-03-17 03:05:16 -0400834 if (!err)
835 insert_binfmt(&misc_format);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836 return err;
837}
838
839static void __exit exit_misc_binfmt(void)
840{
841 unregister_binfmt(&misc_format);
842 unregister_filesystem(&bm_fs_type);
843}
844
845core_initcall(init_misc_binfmt);
846module_exit(exit_misc_binfmt);
847MODULE_LICENSE("GPL");