init/initramfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/init.h>
   3 #include <linux/fs.h>
   4 #include <linux/slab.h>
   5 #include <linux/types.h>
   6 #include <linux/fcntl.h>
   7 #include <linux/delay.h>
   8 #include <linux/string.h>
   9 #include <linux/dirent.h>
  10 #include <linux/syscalls.h>
  11 #include <linux/utime.h>
  12 #include <linux/file.h>
  13 #include <linux/memblock.h>
  14 #include <linux/namei.h>
  15 #include <linux/init_syscalls.h>
  16
  17 static ssize_t __init xwrite(struct file *file, const char *p, size_t count,
  18                 loff_t *pos)
  19 {
  20         ssize_t out = 0;
  21
  22         /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
  23         while (count) {
  24                 ssize_t rv = kernel_write(file, p, count, pos);
  25
  26                 if (rv < 0) {
  27                         if (rv == -EINTR || rv == -EAGAIN)
  28                                 continue;
  29                         return out ? out : rv;
  30                 } else if (rv == 0)
  31                         break;
  32
  33                 p += rv;
  34                 out += rv;
  35                 count -= rv;
  36         }
  37
  38         return out;
  39 }
  40
  41 static __initdata char *message;
  42 static void __init error(char *x)
  43 {
  44         if (!message)
  45                 message = x;
  46 }
  47
  48 /* link hash */
  49
  50 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
  51
  52 static __initdata struct hash {
  53         int ino, minor, major;
  54         umode_t mode;
  55         struct hash *next;
  56         char name[N_ALIGN(PATH_MAX)];
  57 } *head[32];
  58
  59 static inline int hash(int major, int minor, int ino)
  60 {
  61         unsigned long tmp = ino + minor + (major << 3);
  62         tmp += tmp >> 5;
  63         return tmp & 31;
  64 }
  65
  66 static char __init *find_link(int major, int minor, int ino,
  67                               umode_t mode, char *name)
  68 {
  69         struct hash **p, *q;
  70         for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
  71                 if ((*p)->ino != ino)
  72                         continue;
  73                 if ((*p)->minor != minor)
  74                         continue;
  75                 if ((*p)->major != major)
  76                         continue;
  77                 if (((*p)->mode ^ mode) & S_IFMT)
  78                         continue;
  79                 return (*p)->name;
  80         }
  81         q = kmalloc(sizeof(struct hash), GFP_KERNEL);
  82         if (!q)
  83                 panic("can't allocate link hash entry");
  84         q->major = major;
  85         q->minor = minor;
  86         q->ino = ino;
  87         q->mode = mode;
  88         strcpy(q->name, name);
  89         q->next = NULL;
  90         *p = q;
  91         return NULL;
  92 }
  93
  94 static void __init free_hash(void)
  95 {
  96         struct hash **p, *q;
  97         for (p = head; p < head + 32; p++) {
  98                 while (*p) {
  99                         q = *p;
 100                         *p = q->next;
 101                         kfree(q);
 102                 }
 103         }
 104 }
 105
 106 static long __init do_utime(char *filename, time64_t mtime)
 107 {
 108         struct timespec64 t[2];
 109
 110         t[0].tv_sec = mtime;
 111         t[0].tv_nsec = 0;
 112         t[1].tv_sec = mtime;
 113         t[1].tv_nsec = 0;
 114         return init_utimes(filename, t);
 115 }
 116
 117 static __initdata LIST_HEAD(dir_list);
 118 struct dir_entry {
 119         struct list_head list;
 120         char *name;
 121         time64_t mtime;
 122 };
 123
 124 static void __init dir_add(const char *name, time64_t mtime)
 125 {
 126         struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
 127         if (!de)
 128                 panic("can't allocate dir_entry buffer");
 129         INIT_LIST_HEAD(&de->list);
 130         de->name = kstrdup(name, GFP_KERNEL);
 131         de->mtime = mtime;
 132         list_add(&de->list, &dir_list);
 133 }
 134
 135 static void __init dir_utime(void)
 136 {
 137         struct dir_entry *de, *tmp;
 138         list_for_each_entry_safe(de, tmp, &dir_list, list) {
 139                 list_del(&de->list);
 140                 do_utime(de->name, de->mtime);
 141                 kfree(de->name);
 142                 kfree(de);
 143         }
 144 }
 145
 146 static __initdata time64_t mtime;
 147
 148 /* cpio header parsing */
 149
 150 static __initdata unsigned long ino, major, minor, nlink;
 151 static __initdata umode_t mode;
 152 static __initdata unsigned long body_len, name_len;
 153 static __initdata uid_t uid;
 154 static __initdata gid_t gid;
 155 static __initdata unsigned rdev;
 156
 157 static void __init parse_header(char *s)
 158 {
 159         unsigned long parsed[12];
 160         char buf[9];
 161         int i;
 162
 163         buf[8] = '\0';
 164         for (i = 0, s += 6; i < 12; i++, s += 8) {
 165                 memcpy(buf, s, 8);
 166                 parsed[i] = simple_strtoul(buf, NULL, 16);
 167         }
 168         ino = parsed[0];
 169         mode = parsed[1];
 170         uid = parsed[2];
 171         gid = parsed[3];
 172         nlink = parsed[4];
 173         mtime = parsed[5]; /* breaks in y2106 */
 174         body_len = parsed[6];
 175         major = parsed[7];
 176         minor = parsed[8];
 177         rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
 178         name_len = parsed[11];
 179 }
 180
 181 /* FSM */
 182
 183 static __initdata enum state {
 184         Start,
 185         Collect,
 186         GotHeader,
 187         SkipIt,
 188         GotName,
 189         CopyFile,
 190         GotSymlink,
 191         Reset
 192 } state, next_state;
 193
 194 static __initdata char *victim;
 195 static unsigned long byte_count __initdata;
 196 static __initdata loff_t this_header, next_header;
 197
 198 static inline void __init eat(unsigned n)
 199 {
 200         victim += n;
 201         this_header += n;
 202         byte_count -= n;
 203 }
 204
 205 static __initdata char *collected;
 206 static long remains __initdata;
 207 static __initdata char *collect;
 208
 209 static void __init read_into(char *buf, unsigned size, enum state next)
 210 {
 211         if (byte_count >= size) {
 212                 collected = victim;
 213                 eat(size);
 214                 state = next;
 215         } else {
 216                 collect = collected = buf;
 217                 remains = size;
 218                 next_state = next;
 219                 state = Collect;
 220         }
 221 }
 222
 223 static __initdata char *header_buf, *symlink_buf, *name_buf;
 224
 225 static int __init do_start(void)
 226 {
 227         read_into(header_buf, 110, GotHeader);
 228         return 0;
 229 }
 230
 231 static int __init do_collect(void)
 232 {
 233         unsigned long n = remains;
 234         if (byte_count < n)
 235                 n = byte_count;
 236         memcpy(collect, victim, n);
 237         eat(n);
 238         collect += n;
 239         if ((remains -= n) != 0)
 240                 return 1;
 241         state = next_state;
 242         return 0;
 243 }
 244
 245 static int __init do_header(void)
 246 {
 247         if (memcmp(collected, "070707", 6)==0) {
 248                 error("incorrect cpio method used: use -H newc option");
 249                 return 1;
 250         }
 251         if (memcmp(collected, "070701", 6)) {
 252                 error("no cpio magic");
 253                 return 1;
 254         }
 255         parse_header(collected);
 256         next_header = this_header + N_ALIGN(name_len) + body_len;
 257         next_header = (next_header + 3) & ~3;
 258         state = SkipIt;
 259         if (name_len <= 0 || name_len > PATH_MAX)
 260                 return 0;
 261         if (S_ISLNK(mode)) {
 262                 if (body_len > PATH_MAX)
 263                         return 0;
 264                 collect = collected = symlink_buf;
 265                 remains = N_ALIGN(name_len) + body_len;
 266                 next_state = GotSymlink;
 267                 state = Collect;
 268                 return 0;
 269         }
 270         if (S_ISREG(mode) || !body_len)
 271                 read_into(name_buf, N_ALIGN(name_len), GotName);
 272         return 0;
 273 }
 274
 275 static int __init do_skip(void)
 276 {
 277         if (this_header + byte_count < next_header) {
 278                 eat(byte_count);
 279                 return 1;
 280         } else {
 281                 eat(next_header - this_header);
 282                 state = next_state;
 283                 return 0;
 284         }
 285 }
 286
 287 static int __init do_reset(void)
 288 {
 289         while (byte_count && *victim == '\0')
 290                 eat(1);
 291         if (byte_count && (this_header & 3))
 292                 error("broken padding");
 293         return 1;
 294 }
 295
 296 static void __init clean_path(char *path, umode_t fmode)
 297 {
 298         struct kstat st;
 299
 300         if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
 301             (st.mode ^ fmode) & S_IFMT) {
 302                 if (S_ISDIR(st.mode))
 303                         init_rmdir(path);
 304                 else
 305                         init_unlink(path);
 306         }
 307 }
 308
 309 static int __init maybe_link(void)
 310 {
 311         if (nlink >= 2) {
 312                 char *old = find_link(major, minor, ino, mode, collected);
 313                 if (old) {
 314                         clean_path(collected, 0);
 315                         return (init_link(old, collected) < 0) ? -1 : 1;
 316                 }
 317         }
 318         return 0;
 319 }
 320
 321 static __initdata struct file *wfile;
 322 static __initdata loff_t wfile_pos;
 323
 324 static int __init do_name(void)
 325 {
 326         state = SkipIt;
 327         next_state = Reset;
 328         if (strcmp(collected, "TRAILER!!!") == 0) {
 329                 free_hash();
 330                 return 0;
 331         }
 332         clean_path(collected, mode);
 333         if (S_ISREG(mode)) {
 334                 int ml = maybe_link();
 335                 if (ml >= 0) {
 336                         int openflags = O_WRONLY|O_CREAT;
 337                         if (ml != 1)
 338                                 openflags |= O_TRUNC;
 339                         wfile = filp_open(collected, openflags, mode);
 340                         if (IS_ERR(wfile))
 341                                 return 0;
 342                         wfile_pos = 0;
 343
 344                         vfs_fchown(wfile, uid, gid);
 345                         vfs_fchmod(wfile, mode);
 346                         if (body_len)
 347                                 vfs_truncate(&wfile->f_path, body_len);
 348                         state = CopyFile;
 349                 }
 350         } else if (S_ISDIR(mode)) {
 351                 init_mkdir(collected, mode);
 352                 init_chown(collected, uid, gid, 0);
 353                 init_chmod(collected, mode);
 354                 dir_add(collected, mtime);
 355         } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
 356                    S_ISFIFO(mode) || S_ISSOCK(mode)) {
 357                 if (maybe_link() == 0) {
 358                         init_mknod(collected, mode, rdev);
 359                         init_chown(collected, uid, gid, 0);
 360                         init_chmod(collected, mode);
 361                         do_utime(collected, mtime);
 362                 }
 363         }
 364         return 0;
 365 }
 366
 367 static int __init do_copy(void)
 368 {
 369         if (byte_count >= body_len) {
 370                 struct timespec64 t[2] = { };
 371                 if (xwrite(wfile, victim, body_len, &wfile_pos) != body_len)
 372                         error("write error");
 373
 374                 t[0].tv_sec = mtime;
 375                 t[1].tv_sec = mtime;
 376                 vfs_utimes(&wfile->f_path, t);
 377
 378                 fput(wfile);
 379                 eat(body_len);
 380                 state = SkipIt;
 381                 return 0;
 382         } else {
 383                 if (xwrite(wfile, victim, byte_count, &wfile_pos) != byte_count)
 384                         error("write error");
 385                 body_len -= byte_count;
 386                 eat(byte_count);
 387                 return 1;
 388         }
 389 }
 390
 391 static int __init do_symlink(void)
 392 {
 393         collected[N_ALIGN(name_len) + body_len] = '\0';
 394         clean_path(collected, 0);
 395         init_symlink(collected + N_ALIGN(name_len), collected);
 396         init_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
 397         do_utime(collected, mtime);
 398         state = SkipIt;
 399         next_state = Reset;
 400         return 0;
 401 }
 402
 403 static __initdata int (*actions[])(void) = {
 404         [Start]         = do_start,
 405         [Collect]       = do_collect,
 406         [GotHeader]     = do_header,
 407         [SkipIt]        = do_skip,
 408         [GotName]       = do_name,
 409         [CopyFile]      = do_copy,
 410         [GotSymlink]    = do_symlink,
 411         [Reset]         = do_reset,
 412 };
 413
 414 static long __init write_buffer(char *buf, unsigned long len)
 415 {
 416         byte_count = len;
 417         victim = buf;
 418
 419         while (!actions[state]())
 420                 ;
 421         return len - byte_count;
 422 }
 423
 424 static long __init flush_buffer(void *bufv, unsigned long len)
 425 {
 426         char *buf = (char *) bufv;
 427         long written;
 428         long origLen = len;
 429         if (message)
 430                 return -1;
 431         while ((written = write_buffer(buf, len)) < len && !message) {
 432                 char c = buf[written];
 433                 if (c == '0') {
 434                         buf += written;
 435                         len -= written;
 436                         state = Start;
 437                 } else if (c == 0) {
 438                         buf += written;
 439                         len -= written;
 440                         state = Reset;
 441                 } else
 442                         error("junk within compressed archive");
 443         }
 444         return origLen;
 445 }
 446
 447 static unsigned long my_inptr; /* index of next byte to be processed in inbuf */
 448
 449 #include <linux/decompress/generic.h>
 450
 451 static char * __init unpack_to_rootfs(char *buf, unsigned long len)
 452 {
 453         long written;
 454         decompress_fn decompress;
 455         const char *compress_name;
 456         static __initdata char msg_buf[64];
 457
 458         header_buf = kmalloc(110, GFP_KERNEL);
 459         symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
 460         name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
 461
 462         if (!header_buf || !symlink_buf || !name_buf)
 463                 panic("can't allocate buffers");
 464
 465         state = Start;
 466         this_header = 0;
 467         message = NULL;
 468         while (!message && len) {
 469                 loff_t saved_offset = this_header;
 470                 if (*buf == '0' && !(this_header & 3)) {
 471                         state = Start;
 472                         written = write_buffer(buf, len);
 473                         buf += written;
 474                         len -= written;
 475                         continue;
 476                 }
 477                 if (!*buf) {
 478                         buf++;
 479                         len--;
 480                         this_header++;
 481                         continue;
 482                 }
 483                 this_header = 0;
 484                 decompress = decompress_method(buf, len, &compress_name);
 485                 pr_debug("Detected %s compressed data\n", compress_name);
 486                 if (decompress) {
 487                         int res = decompress(buf, len, NULL, flush_buffer, NULL,
 488                                    &my_inptr, error);
 489                         if (res)
 490                                 error("decompressor failed");
 491                 } else if (compress_name) {
 492                         if (!message) {
 493                                 snprintf(msg_buf, sizeof msg_buf,
 494                                          "compression method %s not configured",
 495                                          compress_name);
 496                                 message = msg_buf;
 497                         }
 498                 } else
 499                         error("invalid magic at start of compressed archive");
 500                 if (state != Reset)
 501                         error("junk at the end of compressed archive");
 502                 this_header = saved_offset + my_inptr;
 503                 buf += my_inptr;
 504                 len -= my_inptr;
 505         }
 506         dir_utime();
 507         kfree(name_buf);
 508         kfree(symlink_buf);
 509         kfree(header_buf);
 510         return message;
 511 }
 512
 513 static int __initdata do_retain_initrd;
 514
 515 static int __init retain_initrd_param(char *str)
 516 {
 517         if (*str)
 518                 return 0;
 519         do_retain_initrd = 1;
 520         return 1;
 521 }
 522 __setup("retain_initrd", retain_initrd_param);
 523
 524 #ifdef CONFIG_ARCH_HAS_KEEPINITRD
 525 static int __init keepinitrd_setup(char *__unused)
 526 {
 527         do_retain_initrd = 1;
 528         return 1;
 529 }
 530 __setup("keepinitrd", keepinitrd_setup);
 531 #endif
 532
 533 extern char __initramfs_start[];
 534 extern unsigned long __initramfs_size;
 535 #include <linux/initrd.h>
 536 #include <linux/kexec.h>
 537
 538 void __weak free_initrd_mem(unsigned long start, unsigned long end)
 539 {
 540 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
 541         unsigned long aligned_start = ALIGN_DOWN(start, PAGE_SIZE);
 542         unsigned long aligned_end = ALIGN(end, PAGE_SIZE);
 543
 544         memblock_free(__pa(aligned_start), aligned_end - aligned_start);
 545 #endif
 546
 547         free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
 548                         "initrd");
 549 }
 550
 551 #ifdef CONFIG_KEXEC_CORE
 552 static bool __init kexec_free_initrd(void)
 553 {
 554         unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
 555         unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
 556
 557         /*
 558          * If the initrd region is overlapped with crashkernel reserved region,
 559          * free only memory that is not part of crashkernel region.
 560          */
 561         if (initrd_start >= crashk_end || initrd_end <= crashk_start)
 562                 return false;
 563
 564         /*
 565          * Initialize initrd memory region since the kexec boot does not do.
 566          */
 567         memset((void *)initrd_start, 0, initrd_end - initrd_start);
 568         if (initrd_start < crashk_start)
 569                 free_initrd_mem(initrd_start, crashk_start);
 570         if (initrd_end > crashk_end)
 571                 free_initrd_mem(crashk_end, initrd_end);
 572         return true;
 573 }
 574 #else
 575 static inline bool kexec_free_initrd(void)
 576 {
 577         return false;
 578 }
 579 #endif /* CONFIG_KEXEC_CORE */
 580
 581 #ifdef CONFIG_BLK_DEV_RAM
 582 static void __init populate_initrd_image(char *err)
 583 {
 584         ssize_t written;
 585         struct file *file;
 586         loff_t pos = 0;
 587
 588         unpack_to_rootfs(__initramfs_start, __initramfs_size);
 589
 590         printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
 591                         err);
 592         file = filp_open("/initrd.image", O_WRONLY | O_CREAT, 0700);
 593         if (IS_ERR(file))
 594                 return;
 595
 596         written = xwrite(file, (char *)initrd_start, initrd_end - initrd_start,
 597                         &pos);
 598         if (written != initrd_end - initrd_start)
 599                 pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
 600                        written, initrd_end - initrd_start);
 601         fput(file);
 602 }
 603 #endif /* CONFIG_BLK_DEV_RAM */
 604
 605 static int __init populate_rootfs(void)
 606 {
 607         /* Load the built in initramfs */
 608         char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
 609         if (err)
 610                 panic("%s", err); /* Failed to decompress INTERNAL initramfs */
 611
 612         if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
 613                 goto done;
 614
 615         if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
 616                 printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
 617         else
 618                 printk(KERN_INFO "Unpacking initramfs...\n");
 619
 620         err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
 621         if (err) {
 622 #ifdef CONFIG_BLK_DEV_RAM
 623                 populate_initrd_image(err);
 624 #else
 625                 printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 626 #endif
 627         }
 628
 629 done:
 630         /*
 631          * If the initrd region is overlapped with crashkernel reserved region,
 632          * free only memory that is not part of crashkernel region.
 633          */
 634         if (!do_retain_initrd && initrd_start && !kexec_free_initrd())
 635                 free_initrd_mem(initrd_start, initrd_end);
 636         initrd_start = 0;
 637         initrd_end = 0;
 638
 639         flush_delayed_fput();
 640         return 0;
 641 }
 642 rootfs_initcall(populate_rootfs);