| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * binfmt_misc.c |
| 4 | * |
| 5 | * Copyright (C) 1997 Richard Günther |
| 6 | * |
| 7 | * binfmt_misc detects binaries via a magic or filename extension and invokes |
| 8 | * a specified wrapper. See Documentation/admin-guide/binfmt-misc.rst for more details. |
| 9 | */ |
| 10 | |
| 11 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 12 | |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/init.h> |
| 16 | #include <linux/sched/mm.h> |
| 17 | #include <linux/magic.h> |
| 18 | #include <linux/binfmts.h> |
| 19 | #include <linux/slab.h> |
| 20 | #include <linux/ctype.h> |
| 21 | #include <linux/string_helpers.h> |
| 22 | #include <linux/file.h> |
| 23 | #include <linux/pagemap.h> |
| 24 | #include <linux/namei.h> |
| 25 | #include <linux/mount.h> |
| 26 | #include <linux/fs_context.h> |
| 27 | #include <linux/syscalls.h> |
| 28 | #include <linux/fs.h> |
| 29 | #include <linux/uaccess.h> |
| 30 | |
| 31 | #include "internal.h" |
| 32 | |
| 33 | #ifdef DEBUG |
| 34 | # define USE_DEBUG 1 |
| 35 | #else |
| 36 | # define USE_DEBUG 0 |
| 37 | #endif |
| 38 | |
| 39 | enum { |
| 40 | VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */ |
| 41 | }; |
| 42 | |
| 43 | static LIST_HEAD(entries); |
| 44 | static int enabled = 1; |
| 45 | |
| 46 | enum {Enabled, Magic}; |
| 47 | #define MISC_FMT_PRESERVE_ARGV0 (1UL << 31) |
| 48 | #define MISC_FMT_OPEN_BINARY (1UL << 30) |
| 49 | #define MISC_FMT_CREDENTIALS (1UL << 29) |
| 50 | #define MISC_FMT_OPEN_FILE (1UL << 28) |
| 51 | |
| 52 | typedef struct { |
| 53 | struct list_head list; |
| 54 | unsigned long flags; /* type, status, etc. */ |
| 55 | int offset; /* offset of magic */ |
| 56 | int size; /* size of magic/mask */ |
| 57 | char *magic; /* magic or filename extension */ |
| 58 | char *mask; /* mask, NULL for exact match */ |
| 59 | const char *interpreter; /* filename of interpreter */ |
| 60 | char *name; |
| 61 | struct dentry *dentry; |
| 62 | struct file *interp_file; |
| 63 | } Node; |
| 64 | |
| 65 | static DEFINE_RWLOCK(entries_lock); |
| 66 | static struct file_system_type bm_fs_type; |
| 67 | static struct vfsmount *bm_mnt; |
| 68 | static int entry_count; |
| 69 | |
| 70 | /* |
| 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 | /* |
| 86 | * Check if we support the binfmt |
| 87 | * if we do, return the node, else NULL |
| 88 | * locking is done in load_misc_binary |
| 89 | */ |
| 90 | static Node *check_file(struct linux_binprm *bprm) |
| 91 | { |
| 92 | char *p = strrchr(bprm->interp, '.'); |
| 93 | struct list_head *l; |
| 94 | |
| 95 | /* Walk all the registered handlers. */ |
| 96 | list_for_each(l, &entries) { |
| 97 | Node *e = list_entry(l, Node, list); |
| 98 | char *s; |
| 99 | int j; |
| 100 | |
| 101 | /* Make sure this one is currently enabled. */ |
| 102 | if (!test_bit(Enabled, &e->flags)) |
| 103 | continue; |
| 104 | |
| 105 | /* Do matching based on extension if applicable. */ |
| 106 | if (!test_bit(Magic, &e->flags)) { |
| 107 | if (p && !strcmp(e->magic, p + 1)) |
| 108 | return e; |
| 109 | continue; |
| 110 | } |
| 111 | |
| 112 | /* Do matching based on magic & mask. */ |
| 113 | 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 | */ |
| 132 | static int load_misc_binary(struct linux_binprm *bprm) |
| 133 | { |
| 134 | Node *fmt; |
| 135 | struct file *interp_file = NULL; |
| 136 | int retval; |
| 137 | |
| 138 | retval = -ENOEXEC; |
| 139 | if (!enabled) |
| 140 | return retval; |
| 141 | |
| 142 | /* to keep locking time low, we copy the interpreter string */ |
| 143 | read_lock(&entries_lock); |
| 144 | fmt = check_file(bprm); |
| 145 | if (fmt) |
| 146 | dget(fmt->dentry); |
| 147 | read_unlock(&entries_lock); |
| 148 | if (!fmt) |
| 149 | return retval; |
| 150 | |
| 151 | /* Need to be able to load the file after exec */ |
| 152 | retval = -ENOENT; |
| 153 | if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) |
| 154 | goto ret; |
| 155 | |
| 156 | if (fmt->flags & MISC_FMT_PRESERVE_ARGV0) { |
| 157 | bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0; |
| 158 | } else { |
| 159 | retval = remove_arg_zero(bprm); |
| 160 | if (retval) |
| 161 | goto ret; |
| 162 | } |
| 163 | |
| 164 | if (fmt->flags & MISC_FMT_OPEN_BINARY) |
| 165 | bprm->have_execfd = 1; |
| 166 | |
| 167 | /* make argv[1] be the path to the binary */ |
| 168 | retval = copy_string_kernel(bprm->interp, bprm); |
| 169 | if (retval < 0) |
| 170 | goto ret; |
| 171 | bprm->argc++; |
| 172 | |
| 173 | /* add the interp as argv[0] */ |
| 174 | retval = copy_string_kernel(fmt->interpreter, bprm); |
| 175 | if (retval < 0) |
| 176 | goto ret; |
| 177 | bprm->argc++; |
| 178 | |
| 179 | /* Update interp in case binfmt_script needs it. */ |
| 180 | retval = bprm_change_interp(fmt->interpreter, bprm); |
| 181 | if (retval < 0) |
| 182 | goto ret; |
| 183 | |
| 184 | if (fmt->flags & MISC_FMT_OPEN_FILE) { |
| 185 | interp_file = file_clone_open(fmt->interp_file); |
| 186 | if (!IS_ERR(interp_file)) |
| 187 | deny_write_access(interp_file); |
| 188 | } else { |
| 189 | interp_file = open_exec(fmt->interpreter); |
| 190 | } |
| 191 | retval = PTR_ERR(interp_file); |
| 192 | if (IS_ERR(interp_file)) |
| 193 | goto ret; |
| 194 | |
| 195 | bprm->interpreter = interp_file; |
| 196 | if (fmt->flags & MISC_FMT_CREDENTIALS) |
| 197 | bprm->execfd_creds = 1; |
| 198 | |
| 199 | retval = 0; |
| 200 | ret: |
| 201 | dput(fmt->dentry); |
| 202 | return retval; |
| 203 | } |
| 204 | |
| 205 | /* Command parsers */ |
| 206 | |
| 207 | /* |
| 208 | * parses and copies one argument enclosed in del from *sp to *dp, |
| 209 | * recognising the \x special. |
| 210 | * returns pointer to the copied argument or NULL in case of an |
| 211 | * error (and sets err) or null argument length. |
| 212 | */ |
| 213 | static char *scanarg(char *s, char del) |
| 214 | { |
| 215 | char c; |
| 216 | |
| 217 | while ((c = *s++) != del) { |
| 218 | if (c == '\\' && *s == 'x') { |
| 219 | s++; |
| 220 | if (!isxdigit(*s++)) |
| 221 | return NULL; |
| 222 | if (!isxdigit(*s++)) |
| 223 | return NULL; |
| 224 | } |
| 225 | } |
| 226 | s[-1] ='\0'; |
| 227 | return s; |
| 228 | } |
| 229 | |
| 230 | static char *check_special_flags(char *sfs, Node *e) |
| 231 | { |
| 232 | char *p = sfs; |
| 233 | int cont = 1; |
| 234 | |
| 235 | /* special flags */ |
| 236 | while (cont) { |
| 237 | switch (*p) { |
| 238 | case 'P': |
| 239 | pr_debug("register: flag: P (preserve argv0)\n"); |
| 240 | p++; |
| 241 | e->flags |= MISC_FMT_PRESERVE_ARGV0; |
| 242 | break; |
| 243 | case 'O': |
| 244 | pr_debug("register: flag: O (open binary)\n"); |
| 245 | p++; |
| 246 | e->flags |= MISC_FMT_OPEN_BINARY; |
| 247 | break; |
| 248 | case 'C': |
| 249 | pr_debug("register: flag: C (preserve creds)\n"); |
| 250 | p++; |
| 251 | /* this flags also implies the |
| 252 | open-binary flag */ |
| 253 | e->flags |= (MISC_FMT_CREDENTIALS | |
| 254 | MISC_FMT_OPEN_BINARY); |
| 255 | break; |
| 256 | case 'F': |
| 257 | pr_debug("register: flag: F: open interpreter file now\n"); |
| 258 | p++; |
| 259 | e->flags |= MISC_FMT_OPEN_FILE; |
| 260 | break; |
| 261 | default: |
| 262 | cont = 0; |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | return p; |
| 267 | } |
| 268 | |
| 269 | /* |
| 270 | * This registers a new binary format, it recognises the syntax |
| 271 | * ':name:type:offset:magic:mask:interpreter:flags' |
| 272 | * where the ':' is the IFS, that can be chosen with the first char |
| 273 | */ |
| 274 | static Node *create_entry(const char __user *buffer, size_t count) |
| 275 | { |
| 276 | Node *e; |
| 277 | int memsize, err; |
| 278 | char *buf, *p; |
| 279 | char del; |
| 280 | |
| 281 | pr_debug("register: received %zu bytes\n", count); |
| 282 | |
| 283 | /* some sanity checks */ |
| 284 | err = -EINVAL; |
| 285 | if ((count < 11) || (count > MAX_REGISTER_LENGTH)) |
| 286 | goto out; |
| 287 | |
| 288 | err = -ENOMEM; |
| 289 | memsize = sizeof(Node) + count + 8; |
| 290 | e = kmalloc(memsize, GFP_KERNEL); |
| 291 | if (!e) |
| 292 | goto out; |
| 293 | |
| 294 | p = buf = (char *)e + sizeof(Node); |
| 295 | |
| 296 | memset(e, 0, sizeof(Node)); |
| 297 | if (copy_from_user(buf, buffer, count)) |
| 298 | goto efault; |
| 299 | |
| 300 | del = *p++; /* delimeter */ |
| 301 | |
| 302 | pr_debug("register: delim: %#x {%c}\n", del, del); |
| 303 | |
| 304 | /* Pad the buffer with the delim to simplify parsing below. */ |
| 305 | memset(buf + count, del, 8); |
| 306 | |
| 307 | /* Parse the 'name' field. */ |
| 308 | e->name = p; |
| 309 | p = strchr(p, del); |
| 310 | if (!p) |
| 311 | goto einval; |
| 312 | *p++ = '\0'; |
| 313 | if (!e->name[0] || |
| 314 | !strcmp(e->name, ".") || |
| 315 | !strcmp(e->name, "..") || |
| 316 | strchr(e->name, '/')) |
| 317 | goto einval; |
| 318 | |
| 319 | pr_debug("register: name: {%s}\n", e->name); |
| 320 | |
| 321 | /* Parse the 'type' field. */ |
| 322 | switch (*p++) { |
| 323 | case 'E': |
| 324 | pr_debug("register: type: E (extension)\n"); |
| 325 | e->flags = 1 << Enabled; |
| 326 | break; |
| 327 | case 'M': |
| 328 | pr_debug("register: type: M (magic)\n"); |
| 329 | e->flags = (1 << Enabled) | (1 << Magic); |
| 330 | break; |
| 331 | default: |
| 332 | goto einval; |
| 333 | } |
| 334 | if (*p++ != del) |
| 335 | goto einval; |
| 336 | |
| 337 | if (test_bit(Magic, &e->flags)) { |
| 338 | /* Handle the 'M' (magic) format. */ |
| 339 | char *s; |
| 340 | |
| 341 | /* Parse the 'offset' field. */ |
| 342 | s = strchr(p, del); |
| 343 | if (!s) |
| 344 | goto einval; |
| 345 | *s = '\0'; |
| 346 | if (p != s) { |
| 347 | int r = kstrtoint(p, 10, &e->offset); |
| 348 | if (r != 0 || e->offset < 0) |
| 349 | goto einval; |
| 350 | } |
| 351 | p = s; |
| 352 | if (*p++) |
| 353 | goto einval; |
| 354 | pr_debug("register: offset: %#x\n", e->offset); |
| 355 | |
| 356 | /* Parse the 'magic' field. */ |
| 357 | e->magic = p; |
| 358 | p = scanarg(p, del); |
| 359 | if (!p) |
| 360 | goto einval; |
| 361 | if (!e->magic[0]) |
| 362 | goto einval; |
| 363 | if (USE_DEBUG) |
| 364 | print_hex_dump_bytes( |
| 365 | KBUILD_MODNAME ": register: magic[raw]: ", |
| 366 | DUMP_PREFIX_NONE, e->magic, p - e->magic); |
| 367 | |
| 368 | /* Parse the 'mask' field. */ |
| 369 | e->mask = p; |
| 370 | p = scanarg(p, del); |
| 371 | if (!p) |
| 372 | goto einval; |
| 373 | if (!e->mask[0]) { |
| 374 | e->mask = NULL; |
| 375 | pr_debug("register: mask[raw]: none\n"); |
| 376 | } else if (USE_DEBUG) |
| 377 | print_hex_dump_bytes( |
| 378 | KBUILD_MODNAME ": register: mask[raw]: ", |
| 379 | DUMP_PREFIX_NONE, e->mask, p - e->mask); |
| 380 | |
| 381 | /* |
| 382 | * Decode the magic & mask fields. |
| 383 | * Note: while we might have accepted embedded NUL bytes from |
| 384 | * above, the unescape helpers here will stop at the first one |
| 385 | * it encounters. |
| 386 | */ |
| 387 | e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX); |
| 388 | if (e->mask && |
| 389 | string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size) |
| 390 | goto einval; |
| 391 | if (e->size > BINPRM_BUF_SIZE || |
| 392 | BINPRM_BUF_SIZE - e->size < e->offset) |
| 393 | goto einval; |
| 394 | pr_debug("register: magic/mask length: %i\n", e->size); |
| 395 | if (USE_DEBUG) { |
| 396 | print_hex_dump_bytes( |
| 397 | KBUILD_MODNAME ": register: magic[decoded]: ", |
| 398 | DUMP_PREFIX_NONE, e->magic, e->size); |
| 399 | |
| 400 | if (e->mask) { |
| 401 | int i; |
| 402 | char *masked = kmalloc(e->size, GFP_KERNEL); |
| 403 | |
| 404 | print_hex_dump_bytes( |
| 405 | KBUILD_MODNAME ": register: mask[decoded]: ", |
| 406 | DUMP_PREFIX_NONE, e->mask, e->size); |
| 407 | |
| 408 | if (masked) { |
| 409 | for (i = 0; i < e->size; ++i) |
| 410 | masked[i] = e->magic[i] & e->mask[i]; |
| 411 | print_hex_dump_bytes( |
| 412 | KBUILD_MODNAME ": register: magic[masked]: ", |
| 413 | DUMP_PREFIX_NONE, masked, e->size); |
| 414 | |
| 415 | kfree(masked); |
| 416 | } |
| 417 | } |
| 418 | } |
| 419 | } else { |
| 420 | /* Handle the 'E' (extension) format. */ |
| 421 | |
| 422 | /* Skip the 'offset' field. */ |
| 423 | p = strchr(p, del); |
| 424 | if (!p) |
| 425 | goto einval; |
| 426 | *p++ = '\0'; |
| 427 | |
| 428 | /* Parse the 'magic' field. */ |
| 429 | e->magic = p; |
| 430 | p = strchr(p, del); |
| 431 | if (!p) |
| 432 | goto einval; |
| 433 | *p++ = '\0'; |
| 434 | if (!e->magic[0] || strchr(e->magic, '/')) |
| 435 | goto einval; |
| 436 | pr_debug("register: extension: {%s}\n", e->magic); |
| 437 | |
| 438 | /* Skip the 'mask' field. */ |
| 439 | p = strchr(p, del); |
| 440 | if (!p) |
| 441 | goto einval; |
| 442 | *p++ = '\0'; |
| 443 | } |
| 444 | |
| 445 | /* Parse the 'interpreter' field. */ |
| 446 | e->interpreter = p; |
| 447 | p = strchr(p, del); |
| 448 | if (!p) |
| 449 | goto einval; |
| 450 | *p++ = '\0'; |
| 451 | if (!e->interpreter[0]) |
| 452 | goto einval; |
| 453 | pr_debug("register: interpreter: {%s}\n", e->interpreter); |
| 454 | |
| 455 | /* Parse the 'flags' field. */ |
| 456 | p = check_special_flags(p, e); |
| 457 | if (*p == '\n') |
| 458 | p++; |
| 459 | if (p != buf + count) |
| 460 | goto einval; |
| 461 | |
| 462 | return e; |
| 463 | |
| 464 | out: |
| 465 | return ERR_PTR(err); |
| 466 | |
| 467 | efault: |
| 468 | kfree(e); |
| 469 | return ERR_PTR(-EFAULT); |
| 470 | einval: |
| 471 | kfree(e); |
| 472 | return ERR_PTR(-EINVAL); |
| 473 | } |
| 474 | |
| 475 | /* |
| 476 | * Set status of entry/binfmt_misc: |
| 477 | * '1' enables, '0' disables and '-1' clears entry/binfmt_misc |
| 478 | */ |
| 479 | static int parse_command(const char __user *buffer, size_t count) |
| 480 | { |
| 481 | char s[4]; |
| 482 | |
| 483 | if (count > 3) |
| 484 | return -EINVAL; |
| 485 | if (copy_from_user(s, buffer, count)) |
| 486 | return -EFAULT; |
| 487 | if (!count) |
| 488 | return 0; |
| 489 | if (s[count - 1] == '\n') |
| 490 | count--; |
| 491 | if (count == 1 && s[0] == '0') |
| 492 | return 1; |
| 493 | if (count == 1 && s[0] == '1') |
| 494 | return 2; |
| 495 | if (count == 2 && s[0] == '-' && s[1] == '1') |
| 496 | return 3; |
| 497 | return -EINVAL; |
| 498 | } |
| 499 | |
| 500 | /* generic stuff */ |
| 501 | |
| 502 | static void entry_status(Node *e, char *page) |
| 503 | { |
| 504 | char *dp = page; |
| 505 | const char *status = "disabled"; |
| 506 | |
| 507 | if (test_bit(Enabled, &e->flags)) |
| 508 | status = "enabled"; |
| 509 | |
| 510 | if (!VERBOSE_STATUS) { |
| 511 | sprintf(page, "%s\n", status); |
| 512 | return; |
| 513 | } |
| 514 | |
| 515 | dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter); |
| 516 | |
| 517 | /* print the special flags */ |
| 518 | dp += sprintf(dp, "flags: "); |
| 519 | if (e->flags & MISC_FMT_PRESERVE_ARGV0) |
| 520 | *dp++ = 'P'; |
| 521 | if (e->flags & MISC_FMT_OPEN_BINARY) |
| 522 | *dp++ = 'O'; |
| 523 | if (e->flags & MISC_FMT_CREDENTIALS) |
| 524 | *dp++ = 'C'; |
| 525 | if (e->flags & MISC_FMT_OPEN_FILE) |
| 526 | *dp++ = 'F'; |
| 527 | *dp++ = '\n'; |
| 528 | |
| 529 | if (!test_bit(Magic, &e->flags)) { |
| 530 | sprintf(dp, "extension .%s\n", e->magic); |
| 531 | } else { |
| 532 | dp += sprintf(dp, "offset %i\nmagic ", e->offset); |
| 533 | dp = bin2hex(dp, e->magic, e->size); |
| 534 | if (e->mask) { |
| 535 | dp += sprintf(dp, "\nmask "); |
| 536 | dp = bin2hex(dp, e->mask, e->size); |
| 537 | } |
| 538 | *dp++ = '\n'; |
| 539 | *dp = '\0'; |
| 540 | } |
| 541 | } |
| 542 | |
| 543 | static struct inode *bm_get_inode(struct super_block *sb, int mode) |
| 544 | { |
| 545 | struct inode *inode = new_inode(sb); |
| 546 | |
| 547 | if (inode) { |
| 548 | inode->i_ino = get_next_ino(); |
| 549 | inode->i_mode = mode; |
| 550 | inode->i_atime = inode->i_mtime = inode->i_ctime = |
| 551 | current_time(inode); |
| 552 | } |
| 553 | return inode; |
| 554 | } |
| 555 | |
| 556 | static void bm_evict_inode(struct inode *inode) |
| 557 | { |
| 558 | Node *e = inode->i_private; |
| 559 | |
| 560 | if (e && e->flags & MISC_FMT_OPEN_FILE) |
| 561 | filp_close(e->interp_file, NULL); |
| 562 | |
| 563 | clear_inode(inode); |
| 564 | kfree(e); |
| 565 | } |
| 566 | |
| 567 | static void kill_node(Node *e) |
| 568 | { |
| 569 | struct dentry *dentry; |
| 570 | |
| 571 | write_lock(&entries_lock); |
| 572 | list_del_init(&e->list); |
| 573 | write_unlock(&entries_lock); |
| 574 | |
| 575 | dentry = e->dentry; |
| 576 | drop_nlink(d_inode(dentry)); |
| 577 | d_drop(dentry); |
| 578 | dput(dentry); |
| 579 | simple_release_fs(&bm_mnt, &entry_count); |
| 580 | } |
| 581 | |
| 582 | /* /<entry> */ |
| 583 | |
| 584 | static ssize_t |
| 585 | bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 586 | { |
| 587 | Node *e = file_inode(file)->i_private; |
| 588 | ssize_t res; |
| 589 | char *page; |
| 590 | |
| 591 | page = (char *) __get_free_page(GFP_KERNEL); |
| 592 | if (!page) |
| 593 | return -ENOMEM; |
| 594 | |
| 595 | entry_status(e, page); |
| 596 | |
| 597 | res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page)); |
| 598 | |
| 599 | free_page((unsigned long) page); |
| 600 | return res; |
| 601 | } |
| 602 | |
| 603 | static ssize_t bm_entry_write(struct file *file, const char __user *buffer, |
| 604 | size_t count, loff_t *ppos) |
| 605 | { |
| 606 | struct dentry *root; |
| 607 | Node *e = file_inode(file)->i_private; |
| 608 | int res = parse_command(buffer, count); |
| 609 | |
| 610 | switch (res) { |
| 611 | case 1: |
| 612 | /* Disable this handler. */ |
| 613 | clear_bit(Enabled, &e->flags); |
| 614 | break; |
| 615 | case 2: |
| 616 | /* Enable this handler. */ |
| 617 | set_bit(Enabled, &e->flags); |
| 618 | break; |
| 619 | case 3: |
| 620 | /* Delete this handler. */ |
| 621 | root = file_inode(file)->i_sb->s_root; |
| 622 | inode_lock(d_inode(root)); |
| 623 | |
| 624 | if (!list_empty(&e->list)) |
| 625 | kill_node(e); |
| 626 | |
| 627 | inode_unlock(d_inode(root)); |
| 628 | break; |
| 629 | default: |
| 630 | return res; |
| 631 | } |
| 632 | |
| 633 | return count; |
| 634 | } |
| 635 | |
| 636 | static const struct file_operations bm_entry_operations = { |
| 637 | .read = bm_entry_read, |
| 638 | .write = bm_entry_write, |
| 639 | .llseek = default_llseek, |
| 640 | }; |
| 641 | |
| 642 | /* /register */ |
| 643 | |
| 644 | static ssize_t bm_register_write(struct file *file, const char __user *buffer, |
| 645 | size_t count, loff_t *ppos) |
| 646 | { |
| 647 | Node *e; |
| 648 | struct inode *inode; |
| 649 | struct super_block *sb = file_inode(file)->i_sb; |
| 650 | struct dentry *root = sb->s_root, *dentry; |
| 651 | int err = 0; |
| 652 | struct file *f = NULL; |
| 653 | |
| 654 | e = create_entry(buffer, count); |
| 655 | |
| 656 | if (IS_ERR(e)) |
| 657 | return PTR_ERR(e); |
| 658 | |
| 659 | if (e->flags & MISC_FMT_OPEN_FILE) { |
| 660 | f = open_exec(e->interpreter); |
| 661 | if (IS_ERR(f)) { |
| 662 | pr_notice("register: failed to install interpreter file %s\n", |
| 663 | e->interpreter); |
| 664 | kfree(e); |
| 665 | return PTR_ERR(f); |
| 666 | } |
| 667 | e->interp_file = f; |
| 668 | } |
| 669 | |
| 670 | inode_lock(d_inode(root)); |
| 671 | dentry = lookup_one_len(e->name, root, strlen(e->name)); |
| 672 | err = PTR_ERR(dentry); |
| 673 | if (IS_ERR(dentry)) |
| 674 | goto out; |
| 675 | |
| 676 | err = -EEXIST; |
| 677 | if (d_really_is_positive(dentry)) |
| 678 | goto out2; |
| 679 | |
| 680 | inode = bm_get_inode(sb, S_IFREG | 0644); |
| 681 | |
| 682 | err = -ENOMEM; |
| 683 | if (!inode) |
| 684 | goto out2; |
| 685 | |
| 686 | err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count); |
| 687 | if (err) { |
| 688 | iput(inode); |
| 689 | inode = NULL; |
| 690 | goto out2; |
| 691 | } |
| 692 | |
| 693 | e->dentry = dget(dentry); |
| 694 | inode->i_private = e; |
| 695 | inode->i_fop = &bm_entry_operations; |
| 696 | |
| 697 | d_instantiate(dentry, inode); |
| 698 | write_lock(&entries_lock); |
| 699 | list_add(&e->list, &entries); |
| 700 | write_unlock(&entries_lock); |
| 701 | |
| 702 | err = 0; |
| 703 | out2: |
| 704 | dput(dentry); |
| 705 | out: |
| 706 | inode_unlock(d_inode(root)); |
| 707 | |
| 708 | if (err) { |
| 709 | if (f) |
| 710 | filp_close(f, NULL); |
| 711 | kfree(e); |
| 712 | return err; |
| 713 | } |
| 714 | return count; |
| 715 | } |
| 716 | |
| 717 | static const struct file_operations bm_register_operations = { |
| 718 | .write = bm_register_write, |
| 719 | .llseek = noop_llseek, |
| 720 | }; |
| 721 | |
| 722 | /* /status */ |
| 723 | |
| 724 | static ssize_t |
| 725 | bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) |
| 726 | { |
| 727 | char *s = enabled ? "enabled\n" : "disabled\n"; |
| 728 | |
| 729 | return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); |
| 730 | } |
| 731 | |
| 732 | static ssize_t bm_status_write(struct file *file, const char __user *buffer, |
| 733 | size_t count, loff_t *ppos) |
| 734 | { |
| 735 | int res = parse_command(buffer, count); |
| 736 | struct dentry *root; |
| 737 | |
| 738 | switch (res) { |
| 739 | case 1: |
| 740 | /* Disable all handlers. */ |
| 741 | enabled = 0; |
| 742 | break; |
| 743 | case 2: |
| 744 | /* Enable all handlers. */ |
| 745 | enabled = 1; |
| 746 | break; |
| 747 | case 3: |
| 748 | /* Delete all handlers. */ |
| 749 | root = file_inode(file)->i_sb->s_root; |
| 750 | inode_lock(d_inode(root)); |
| 751 | |
| 752 | while (!list_empty(&entries)) |
| 753 | kill_node(list_first_entry(&entries, Node, list)); |
| 754 | |
| 755 | inode_unlock(d_inode(root)); |
| 756 | break; |
| 757 | default: |
| 758 | return res; |
| 759 | } |
| 760 | |
| 761 | return count; |
| 762 | } |
| 763 | |
| 764 | static const struct file_operations bm_status_operations = { |
| 765 | .read = bm_status_read, |
| 766 | .write = bm_status_write, |
| 767 | .llseek = default_llseek, |
| 768 | }; |
| 769 | |
| 770 | /* Superblock handling */ |
| 771 | |
| 772 | static const struct super_operations s_ops = { |
| 773 | .statfs = simple_statfs, |
| 774 | .evict_inode = bm_evict_inode, |
| 775 | }; |
| 776 | |
| 777 | static int bm_fill_super(struct super_block *sb, struct fs_context *fc) |
| 778 | { |
| 779 | int err; |
| 780 | static const struct tree_descr bm_files[] = { |
| 781 | [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO}, |
| 782 | [3] = {"register", &bm_register_operations, S_IWUSR}, |
| 783 | /* last one */ {""} |
| 784 | }; |
| 785 | |
| 786 | err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files); |
| 787 | if (!err) |
| 788 | sb->s_op = &s_ops; |
| 789 | return err; |
| 790 | } |
| 791 | |
| 792 | static int bm_get_tree(struct fs_context *fc) |
| 793 | { |
| 794 | return get_tree_single(fc, bm_fill_super); |
| 795 | } |
| 796 | |
| 797 | static const struct fs_context_operations bm_context_ops = { |
| 798 | .get_tree = bm_get_tree, |
| 799 | }; |
| 800 | |
| 801 | static int bm_init_fs_context(struct fs_context *fc) |
| 802 | { |
| 803 | fc->ops = &bm_context_ops; |
| 804 | return 0; |
| 805 | } |
| 806 | |
| 807 | static struct linux_binfmt misc_format = { |
| 808 | .module = THIS_MODULE, |
| 809 | .load_binary = load_misc_binary, |
| 810 | }; |
| 811 | |
| 812 | static struct file_system_type bm_fs_type = { |
| 813 | .owner = THIS_MODULE, |
| 814 | .name = "binfmt_misc", |
| 815 | .init_fs_context = bm_init_fs_context, |
| 816 | .kill_sb = kill_litter_super, |
| 817 | }; |
| 818 | MODULE_ALIAS_FS("binfmt_misc"); |
| 819 | |
| 820 | static int __init init_misc_binfmt(void) |
| 821 | { |
| 822 | int err = register_filesystem(&bm_fs_type); |
| 823 | if (!err) |
| 824 | insert_binfmt(&misc_format); |
| 825 | return err; |
| 826 | } |
| 827 | |
| 828 | static void __exit exit_misc_binfmt(void) |
| 829 | { |
| 830 | unregister_binfmt(&misc_format); |
| 831 | unregister_filesystem(&bm_fs_type); |
| 832 | } |
| 833 | |
| 834 | core_initcall(init_misc_binfmt); |
| 835 | module_exit(exit_misc_binfmt); |
| 836 | MODULE_LICENSE("GPL"); |