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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
Mauro Carvalho Chehab34962fb2018-05-08 15:14:57 -03007 * a specified wrapper. See Documentation/admin-guide/binfmt-misc.rst 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>
Ingo Molnar589ee622017-02-04 00:16:44 +010015#include <linux/sched/mm.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 */
Oleg Nesterov50097f72017-10-03 16:15:58 -070057 const char *interpreter; /* filename of interpreter */
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 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 int retval;
135 int fd_binary = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136
137 retval = -ENOEXEC;
138 if (!enabled)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700139 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
141 /* to keep locking time low, we copy the interpreter string */
142 read_lock(&entries_lock);
143 fmt = check_file(bprm);
Oleg Nesterov50097f72017-10-03 16:15:58 -0700144 if (fmt)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700145 dget(fmt->dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 read_unlock(&entries_lock);
147 if (!fmt)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700148 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
David Drysdale51f39a12014-12-12 16:57:29 -0800150 /* Need to be able to load the file after exec */
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700151 retval = -ENOENT;
David Drysdale51f39a12014-12-12 16:57:29 -0800152 if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700153 goto ret;
David Drysdale51f39a12014-12-12 16:57:29 -0800154
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155 if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
Ollie Wildb6a2fea2007-07-19 01:48:16 -0700156 retval = remove_arg_zero(bprm);
157 if (retval)
Mike Frysingere6084d42014-12-10 15:52:10 -0800158 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 }
160
161 if (fmt->flags & MISC_FMT_OPEN_BINARY) {
162
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 /* if the binary should be opened on behalf of the
164 * interpreter than keep it open and assign descriptor
Mike Frysingere6084d42014-12-10 15:52:10 -0800165 * to it
166 */
Yann Droneaudc6cb8982014-12-10 15:45:42 -0800167 fd_binary = get_unused_fd_flags(0);
Mike Frysingere6084d42014-12-10 15:52:10 -0800168 if (fd_binary < 0) {
169 retval = fd_binary;
170 goto ret;
171 }
172 fd_install(fd_binary, bprm->file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173
174 /* if the binary is not readable than enforce mm->dumpable=0
175 regardless of the interpreter's permissions */
Al Viro1b5d7832011-06-19 12:49:47 -0400176 would_dump(bprm, bprm->file);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
178 allow_write_access(bprm->file);
179 bprm->file = NULL;
180
181 /* mark the bprm that fd should be passed to interp */
182 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
183 bprm->interp_data = fd_binary;
184
Mike Frysingere6084d42014-12-10 15:52:10 -0800185 } else {
186 allow_write_access(bprm->file);
187 fput(bprm->file);
188 bprm->file = NULL;
189 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 /* make argv[1] be the path to the binary */
Mike Frysingere6084d42014-12-10 15:52:10 -0800191 retval = copy_strings_kernel(1, &bprm->interp, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800193 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 bprm->argc++;
195
196 /* add the interp as argv[0] */
Oleg Nesterov50097f72017-10-03 16:15:58 -0700197 retval = copy_strings_kernel(1, &fmt->interpreter, bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800199 goto error;
200 bprm->argc++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
Kees Cookb66c5982012-12-20 15:05:16 -0800202 /* Update interp in case binfmt_script needs it. */
Oleg Nesterov50097f72017-10-03 16:15:58 -0700203 retval = bprm_change_interp(fmt->interpreter, bprm);
Kees Cookb66c5982012-12-20 15:05:16 -0800204 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800205 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206
Oleg Nesteroveb23aa02017-10-03 16:15:51 -0700207 if (fmt->flags & MISC_FMT_OPEN_FILE) {
James Bottomley948b7012016-02-17 16:51:16 -0800208 interp_file = filp_clone_open(fmt->interp_file);
209 if (!IS_ERR(interp_file))
210 deny_write_access(interp_file);
211 } else {
Oleg Nesterov50097f72017-10-03 16:15:58 -0700212 interp_file = open_exec(fmt->interpreter);
James Bottomley948b7012016-02-17 16:51:16 -0800213 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800214 retval = PTR_ERR(interp_file);
215 if (IS_ERR(interp_file))
216 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217
218 bprm->file = interp_file;
219 if (fmt->flags & MISC_FMT_CREDENTIALS) {
Christoph Hellwigbdd1d2d2017-09-01 17:39:13 +0200220 loff_t pos = 0;
221
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 /*
223 * No need to call prepare_binprm(), it's already been
224 * done. bprm->buf is stale, update from interp_file.
225 */
226 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
Christoph Hellwigbdd1d2d2017-09-01 17:39:13 +0200227 retval = kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE,
228 &pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 } else
Mike Frysingere6084d42014-12-10 15:52:10 -0800230 retval = prepare_binprm(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
232 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800233 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234
Al Viro3c456bf2012-10-20 21:53:31 -0400235 retval = search_binary_handler(bprm);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236 if (retval < 0)
Mike Frysingere6084d42014-12-10 15:52:10 -0800237 goto error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238
Mike Frysingere6084d42014-12-10 15:52:10 -0800239ret:
Oleg Nesterov43a4f262017-10-03 16:15:55 -0700240 dput(fmt->dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 return retval;
Mike Frysingere6084d42014-12-10 15:52:10 -0800242error:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 if (fd_binary > 0)
Dominik Brodowski2ca2a092018-03-11 11:34:55 +0100244 ksys_close(fd_binary);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 bprm->interp_flags = 0;
246 bprm->interp_data = 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800247 goto ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248}
249
250/* Command parsers */
251
252/*
253 * parses and copies one argument enclosed in del from *sp to *dp,
254 * recognising the \x special.
255 * returns pointer to the copied argument or NULL in case of an
256 * error (and sets err) or null argument length.
257 */
258static char *scanarg(char *s, char del)
259{
260 char c;
261
262 while ((c = *s++) != del) {
263 if (c == '\\' && *s == 'x') {
264 s++;
265 if (!isxdigit(*s++))
266 return NULL;
267 if (!isxdigit(*s++))
268 return NULL;
269 }
270 }
Al Viro7d65cf12014-12-17 05:29:16 -0500271 s[-1] ='\0';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 return s;
273}
274
Mike Frysingere6084d42014-12-10 15:52:10 -0800275static char *check_special_flags(char *sfs, Node *e)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276{
Mike Frysingere6084d42014-12-10 15:52:10 -0800277 char *p = sfs;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 int cont = 1;
279
280 /* special flags */
281 while (cont) {
282 switch (*p) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800283 case 'P':
284 pr_debug("register: flag: P (preserve argv0)\n");
285 p++;
286 e->flags |= MISC_FMT_PRESERVE_ARGV0;
287 break;
288 case 'O':
289 pr_debug("register: flag: O (open binary)\n");
290 p++;
291 e->flags |= MISC_FMT_OPEN_BINARY;
292 break;
293 case 'C':
294 pr_debug("register: flag: C (preserve creds)\n");
295 p++;
296 /* this flags also implies the
297 open-binary flag */
298 e->flags |= (MISC_FMT_CREDENTIALS |
299 MISC_FMT_OPEN_BINARY);
300 break;
James Bottomley948b7012016-02-17 16:51:16 -0800301 case 'F':
302 pr_debug("register: flag: F: open interpreter file now\n");
303 p++;
304 e->flags |= MISC_FMT_OPEN_FILE;
305 break;
Mike Frysingere6084d42014-12-10 15:52:10 -0800306 default:
307 cont = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 }
309 }
310
311 return p;
312}
Mike Frysingere6084d42014-12-10 15:52:10 -0800313
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314/*
315 * This registers a new binary format, it recognises the syntax
316 * ':name:type:offset:magic:mask:interpreter:flags'
317 * where the ':' is the IFS, that can be chosen with the first char
318 */
319static Node *create_entry(const char __user *buffer, size_t count)
320{
321 Node *e;
322 int memsize, err;
323 char *buf, *p;
324 char del;
325
Mike Frysinger6b899c42014-12-10 15:52:08 -0800326 pr_debug("register: received %zu bytes\n", count);
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 /* some sanity checks */
329 err = -EINVAL;
Mike Frysingerbbaecc02014-10-13 15:52:03 -0700330 if ((count < 11) || (count > MAX_REGISTER_LENGTH))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 goto out;
332
333 err = -ENOMEM;
334 memsize = sizeof(Node) + count + 8;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800335 e = kmalloc(memsize, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 if (!e)
337 goto out;
338
339 p = buf = (char *)e + sizeof(Node);
340
341 memset(e, 0, sizeof(Node));
342 if (copy_from_user(buf, buffer, count))
Mike Frysingere6084d42014-12-10 15:52:10 -0800343 goto efault;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344
345 del = *p++; /* delimeter */
346
Mike Frysinger6b899c42014-12-10 15:52:08 -0800347 pr_debug("register: delim: %#x {%c}\n", del, del);
348
349 /* Pad the buffer with the delim to simplify parsing below. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800350 memset(buf + count, del, 8);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351
Mike Frysinger6b899c42014-12-10 15:52:08 -0800352 /* Parse the 'name' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 e->name = p;
354 p = strchr(p, del);
355 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800356 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 *p++ = '\0';
358 if (!e->name[0] ||
359 !strcmp(e->name, ".") ||
360 !strcmp(e->name, "..") ||
361 strchr(e->name, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800362 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800363
364 pr_debug("register: name: {%s}\n", e->name);
365
366 /* Parse the 'type' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 switch (*p++) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800368 case 'E':
369 pr_debug("register: type: E (extension)\n");
370 e->flags = 1 << Enabled;
371 break;
372 case 'M':
373 pr_debug("register: type: M (magic)\n");
374 e->flags = (1 << Enabled) | (1 << Magic);
375 break;
376 default:
Mike Frysingere6084d42014-12-10 15:52:10 -0800377 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 }
379 if (*p++ != del)
Mike Frysingere6084d42014-12-10 15:52:10 -0800380 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800381
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 if (test_bit(Magic, &e->flags)) {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800383 /* Handle the 'M' (magic) format. */
384 char *s;
385
386 /* Parse the 'offset' field. */
387 s = strchr(p, del);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 if (!s)
Mike Frysingere6084d42014-12-10 15:52:10 -0800389 goto einval;
Thadeu Lima de Souza Cascardo5cc41e02018-06-07 17:11:01 -0700390 *s = '\0';
391 if (p != s) {
392 int r = kstrtoint(p, 10, &e->offset);
393 if (r != 0 || e->offset < 0)
394 goto einval;
395 }
396 p = s;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 if (*p++)
Mike Frysingere6084d42014-12-10 15:52:10 -0800398 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800399 pr_debug("register: offset: %#x\n", e->offset);
400
401 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 e->magic = p;
403 p = scanarg(p, del);
404 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800405 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500406 if (!e->magic[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800407 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800408 if (USE_DEBUG)
409 print_hex_dump_bytes(
410 KBUILD_MODNAME ": register: magic[raw]: ",
411 DUMP_PREFIX_NONE, e->magic, p - e->magic);
412
413 /* Parse the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 e->mask = p;
415 p = scanarg(p, del);
416 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800417 goto einval;
Al Viro7d65cf12014-12-17 05:29:16 -0500418 if (!e->mask[0]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 e->mask = NULL;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800420 pr_debug("register: mask[raw]: none\n");
421 } else if (USE_DEBUG)
422 print_hex_dump_bytes(
423 KBUILD_MODNAME ": register: mask[raw]: ",
424 DUMP_PREFIX_NONE, e->mask, p - e->mask);
425
426 /*
427 * Decode the magic & mask fields.
428 * Note: while we might have accepted embedded NUL bytes from
429 * above, the unescape helpers here will stop at the first one
430 * it encounters.
431 */
Andy Shevchenko8d82e182013-04-30 15:27:33 -0700432 e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
433 if (e->mask &&
434 string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
Mike Frysingere6084d42014-12-10 15:52:10 -0800435 goto einval;
Thadeu Lima de Souza Cascardo5cc41e02018-06-07 17:11:01 -0700436 if (e->size > BINPRM_BUF_SIZE ||
437 BINPRM_BUF_SIZE - e->size < e->offset)
Mike Frysingere6084d42014-12-10 15:52:10 -0800438 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800439 pr_debug("register: magic/mask length: %i\n", e->size);
440 if (USE_DEBUG) {
441 print_hex_dump_bytes(
442 KBUILD_MODNAME ": register: magic[decoded]: ",
443 DUMP_PREFIX_NONE, e->magic, e->size);
444
445 if (e->mask) {
446 int i;
Andrew Mortonf7e1ad12014-12-10 15:52:13 -0800447 char *masked = kmalloc(e->size, GFP_KERNEL);
Mike Frysinger6b899c42014-12-10 15:52:08 -0800448
449 print_hex_dump_bytes(
450 KBUILD_MODNAME ": register: mask[decoded]: ",
451 DUMP_PREFIX_NONE, e->mask, e->size);
452
453 if (masked) {
454 for (i = 0; i < e->size; ++i)
455 masked[i] = e->magic[i] & e->mask[i];
456 print_hex_dump_bytes(
457 KBUILD_MODNAME ": register: magic[masked]: ",
458 DUMP_PREFIX_NONE, masked, e->size);
459
460 kfree(masked);
461 }
462 }
463 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 } else {
Mike Frysinger6b899c42014-12-10 15:52:08 -0800465 /* Handle the 'E' (extension) format. */
466
467 /* Skip the 'offset' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 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';
Mike Frysinger6b899c42014-12-10 15:52:08 -0800472
473 /* Parse the 'magic' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 e->magic = p;
475 p = strchr(p, del);
476 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800477 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478 *p++ = '\0';
479 if (!e->magic[0] || strchr(e->magic, '/'))
Mike Frysingere6084d42014-12-10 15:52:10 -0800480 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800481 pr_debug("register: extension: {%s}\n", e->magic);
482
483 /* Skip the 'mask' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 p = strchr(p, del);
485 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800486 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 *p++ = '\0';
488 }
Mike Frysinger6b899c42014-12-10 15:52:08 -0800489
490 /* Parse the 'interpreter' field. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 e->interpreter = p;
492 p = strchr(p, del);
493 if (!p)
Mike Frysingere6084d42014-12-10 15:52:10 -0800494 goto einval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 *p++ = '\0';
496 if (!e->interpreter[0])
Mike Frysingere6084d42014-12-10 15:52:10 -0800497 goto einval;
Mike Frysinger6b899c42014-12-10 15:52:08 -0800498 pr_debug("register: interpreter: {%s}\n", e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499
Mike Frysinger6b899c42014-12-10 15:52:08 -0800500 /* Parse the 'flags' field. */
Mike Frysingere6084d42014-12-10 15:52:10 -0800501 p = check_special_flags(p, e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 if (*p == '\n')
503 p++;
504 if (p != buf + count)
Mike Frysingere6084d42014-12-10 15:52:10 -0800505 goto einval;
506
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 return e;
508
509out:
510 return ERR_PTR(err);
511
Mike Frysingere6084d42014-12-10 15:52:10 -0800512efault:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 kfree(e);
514 return ERR_PTR(-EFAULT);
Mike Frysingere6084d42014-12-10 15:52:10 -0800515einval:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 kfree(e);
517 return ERR_PTR(-EINVAL);
518}
519
520/*
521 * Set status of entry/binfmt_misc:
522 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
523 */
524static int parse_command(const char __user *buffer, size_t count)
525{
526 char s[4];
527
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 if (count > 3)
529 return -EINVAL;
530 if (copy_from_user(s, buffer, count))
531 return -EFAULT;
Arnd Bergmannde8288b2014-10-13 15:52:08 -0700532 if (!count)
533 return 0;
Mike Frysingere6084d42014-12-10 15:52:10 -0800534 if (s[count - 1] == '\n')
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 count--;
536 if (count == 1 && s[0] == '0')
537 return 1;
538 if (count == 1 && s[0] == '1')
539 return 2;
540 if (count == 2 && s[0] == '-' && s[1] == '1')
541 return 3;
542 return -EINVAL;
543}
544
545/* generic stuff */
546
547static void entry_status(Node *e, char *page)
548{
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700549 char *dp = page;
550 const char *status = "disabled";
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551
552 if (test_bit(Enabled, &e->flags))
553 status = "enabled";
554
555 if (!VERBOSE_STATUS) {
556 sprintf(page, "%s\n", status);
557 return;
558 }
559
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700560 dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561
562 /* print the special flags */
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700563 dp += sprintf(dp, "flags: ");
Mike Frysingere6084d42014-12-10 15:52:10 -0800564 if (e->flags & MISC_FMT_PRESERVE_ARGV0)
565 *dp++ = 'P';
566 if (e->flags & MISC_FMT_OPEN_BINARY)
567 *dp++ = 'O';
568 if (e->flags & MISC_FMT_CREDENTIALS)
569 *dp++ = 'C';
James Bottomley948b7012016-02-17 16:51:16 -0800570 if (e->flags & MISC_FMT_OPEN_FILE)
571 *dp++ = 'F';
Mike Frysingere6084d42014-12-10 15:52:10 -0800572 *dp++ = '\n';
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573
574 if (!test_bit(Magic, &e->flags)) {
575 sprintf(dp, "extension .%s\n", e->magic);
576 } else {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700577 dp += sprintf(dp, "offset %i\nmagic ", e->offset);
578 dp = bin2hex(dp, e->magic, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 if (e->mask) {
Rasmus Villemoes6ceafb82015-04-16 12:44:56 -0700580 dp += sprintf(dp, "\nmask ");
581 dp = bin2hex(dp, e->mask, e->size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 }
583 *dp++ = '\n';
584 *dp = '\0';
585 }
586}
587
588static struct inode *bm_get_inode(struct super_block *sb, int mode)
589{
Mike Frysingere6084d42014-12-10 15:52:10 -0800590 struct inode *inode = new_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
592 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -0400593 inode->i_ino = get_next_ino();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 inode->i_mode = mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 inode->i_atime = inode->i_mtime = inode->i_ctime =
Deepa Dinamanic2050a42016-09-14 07:48:06 -0700596 current_time(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 }
598 return inode;
599}
600
Al Virob57922d2010-06-07 14:34:48 -0400601static void bm_evict_inode(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602{
Oleg Nesterov83f91822017-10-03 16:15:48 -0700603 Node *e = inode->i_private;
604
Eryu Guan7e866002017-10-13 15:58:18 -0700605 if (e && e->flags & MISC_FMT_OPEN_FILE)
Oleg Nesterov83f91822017-10-03 16:15:48 -0700606 filp_close(e->interp_file, NULL);
607
Jan Karadbd57682012-05-03 14:48:02 +0200608 clear_inode(inode);
Oleg Nesterov83f91822017-10-03 16:15:48 -0700609 kfree(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610}
611
612static void kill_node(Node *e)
613{
614 struct dentry *dentry;
615
616 write_lock(&entries_lock);
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700617 list_del_init(&e->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618 write_unlock(&entries_lock);
619
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700620 dentry = e->dentry;
621 drop_nlink(d_inode(dentry));
622 d_drop(dentry);
623 dput(dentry);
624 simple_release_fs(&bm_mnt, &entry_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625}
626
627/* /<entry> */
628
629static ssize_t
Mike Frysingere6084d42014-12-10 15:52:10 -0800630bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631{
Al Viro496ad9a2013-01-23 17:07:38 -0500632 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 ssize_t res;
634 char *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635
Mike Frysingere6084d42014-12-10 15:52:10 -0800636 page = (char *) __get_free_page(GFP_KERNEL);
637 if (!page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 return -ENOMEM;
639
640 entry_status(e, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641
Akinobu Mita6e2c10a2008-07-23 21:29:15 -0700642 res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
643
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 free_page((unsigned long) page);
645 return res;
646}
647
648static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
649 size_t count, loff_t *ppos)
650{
651 struct dentry *root;
Al Viro496ad9a2013-01-23 17:07:38 -0500652 Node *e = file_inode(file)->i_private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 int res = parse_command(buffer, count);
654
655 switch (res) {
Mike Frysingere6084d42014-12-10 15:52:10 -0800656 case 1:
657 /* Disable this handler. */
658 clear_bit(Enabled, &e->flags);
659 break;
660 case 2:
661 /* Enable this handler. */
662 set_bit(Enabled, &e->flags);
663 break;
664 case 3:
665 /* Delete this handler. */
Al Viroea7d4c02016-05-29 19:14:03 -0400666 root = file_inode(file)->i_sb->s_root;
Al Viro59551022016-01-22 15:40:57 -0500667 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700669 if (!list_empty(&e->list))
670 kill_node(e);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671
Al Viro59551022016-01-22 15:40:57 -0500672 inode_unlock(d_inode(root));
Mike Frysingere6084d42014-12-10 15:52:10 -0800673 break;
674 default:
675 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 }
Mike Frysingere6084d42014-12-10 15:52:10 -0800677
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 return count;
679}
680
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800681static const struct file_operations bm_entry_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 .read = bm_entry_read,
683 .write = bm_entry_write,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200684 .llseek = default_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685};
686
687/* /register */
688
689static ssize_t bm_register_write(struct file *file, const char __user *buffer,
690 size_t count, loff_t *ppos)
691{
692 Node *e;
693 struct inode *inode;
Al Viroea7d4c02016-05-29 19:14:03 -0400694 struct super_block *sb = file_inode(file)->i_sb;
695 struct dentry *root = sb->s_root, *dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 int err = 0;
697
698 e = create_entry(buffer, count);
699
700 if (IS_ERR(e))
701 return PTR_ERR(e);
702
Al Viro59551022016-01-22 15:40:57 -0500703 inode_lock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 dentry = lookup_one_len(e->name, root, strlen(e->name));
705 err = PTR_ERR(dentry);
706 if (IS_ERR(dentry))
707 goto out;
708
709 err = -EEXIST;
David Howells75c3cfa2015-03-17 22:26:12 +0000710 if (d_really_is_positive(dentry))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 goto out2;
712
713 inode = bm_get_inode(sb, S_IFREG | 0644);
714
715 err = -ENOMEM;
716 if (!inode)
717 goto out2;
718
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400719 err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 if (err) {
721 iput(inode);
722 inode = NULL;
723 goto out2;
724 }
725
James Bottomley948b7012016-02-17 16:51:16 -0800726 if (e->flags & MISC_FMT_OPEN_FILE) {
727 struct file *f;
728
729 f = open_exec(e->interpreter);
730 if (IS_ERR(f)) {
731 err = PTR_ERR(f);
732 pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
733 simple_release_fs(&bm_mnt, &entry_count);
734 iput(inode);
735 inode = NULL;
736 goto out2;
737 }
738 e->interp_file = f;
739 }
740
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741 e->dentry = dget(dentry);
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700742 inode->i_private = e;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 inode->i_fop = &bm_entry_operations;
744
745 d_instantiate(dentry, inode);
746 write_lock(&entries_lock);
747 list_add(&e->list, &entries);
748 write_unlock(&entries_lock);
749
750 err = 0;
751out2:
752 dput(dentry);
753out:
Al Viro59551022016-01-22 15:40:57 -0500754 inode_unlock(d_inode(root));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755
756 if (err) {
757 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 Feng87113e82009-01-06 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))
Oleg Nesterovbaba1b22017-10-03 16:15:45 -0700799 kill_node(list_first_entry(&entries, 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;
Eric Biggerscda37122017-03-25 21:15:37 -0700826 static const 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");