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
  14 static ssize_t __init xwrite(int fd, const char *p, size_t count)
  15 {
  16         ssize_t out = 0;
  17
  18         /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
  19         while (count) {
  20                 ssize_t rv = ksys_write(fd, p, count);
  21
  22                 if (rv < 0) {
  23                         if (rv == -EINTR || rv == -EAGAIN)
  24                                 continue;
  25                         return out ? out : rv;
  26                 } else if (rv == 0)
  27                         break;
  28
  29                 p += rv;
  30                 out += rv;
  31                 count -= rv;
  32         }
  33
  34         return out;
  35 }
  36
  37 static __initdata char *message;
  38 static void __init error(char *x)
  39 {
  40         if (!message)
  41                 message = x;
  42 }
  43
  44 /* link hash */
  45
  46 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
  47
  48 static __initdata struct hash {
  49         int ino, minor, major;
  50         umode_t mode;
  51         struct hash *next;
  52         char name[N_ALIGN(PATH_MAX)];
  53 } *head[32];
  54
  55 static inline int hash(int major, int minor, int ino)
  56 {
  57         unsigned long tmp = ino + minor + (major << 3);
  58         tmp += tmp >> 5;
  59         return tmp & 31;
  60 }
  61
  62 static char __init *find_link(int major, int minor, int ino,
  63                               umode_t mode, char *name)
  64 {
  65         struct hash **p, *q;
  66         for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
  67                 if ((*p)->ino != ino)
  68                         continue;
  69                 if ((*p)->minor != minor)
  70                         continue;
  71                 if ((*p)->major != major)
  72                         continue;
  73                 if (((*p)->mode ^ mode) & S_IFMT)
  74                         continue;
  75                 return (*p)->name;
  76         }
  77         q = kmalloc(sizeof(struct hash), GFP_KERNEL);
  78         if (!q)
  79                 panic("can't allocate link hash entry");
  80         q->major = major;
  81         q->minor = minor;
  82         q->ino = ino;
  83         q->mode = mode;
  84         strcpy(q->name, name);
  85         q->next = NULL;
  86         *p = q;
  87         return NULL;
  88 }
  89
  90 static void __init free_hash(void)
  91 {
  92         struct hash **p, *q;
  93         for (p = head; p < head + 32; p++) {
  94                 while (*p) {
  95                         q = *p;
  96                         *p = q->next;
  97                         kfree(q);
  98                 }
  99         }
 100 }
 101
 102 static long __init do_utime(char *filename, time64_t mtime)
 103 {
 104         struct timespec64 t[2];
 105
 106         t[0].tv_sec = mtime;
 107         t[0].tv_nsec = 0;
 108         t[1].tv_sec = mtime;
 109         t[1].tv_nsec = 0;
 110
 111         return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
 112 }
 113
 114 static __initdata LIST_HEAD(dir_list);
 115 struct dir_entry {
 116         struct list_head list;
 117         char *name;
 118         time64_t mtime;
 119 };
 120
 121 static void __init dir_add(const char *name, time64_t mtime)
 122 {
 123         struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
 124         if (!de)
 125                 panic("can't allocate dir_entry buffer");
 126         INIT_LIST_HEAD(&de->list);
 127         de->name = kstrdup(name, GFP_KERNEL);
 128         de->mtime = mtime;
 129         list_add(&de->list, &dir_list);
 130 }
 131
 132 static void __init dir_utime(void)
 133 {
 134         struct dir_entry *de, *tmp;
 135         list_for_each_entry_safe(de, tmp, &dir_list, list) {
 136                 list_del(&de->list);
 137                 do_utime(de->name, de->mtime);
 138                 kfree(de->name);
 139                 kfree(de);
 140         }
 141 }
 142
 143 static __initdata time64_t mtime;
 144
 145 /* cpio header parsing */
 146
 147 static __initdata unsigned long ino, major, minor, nlink;
 148 static __initdata umode_t mode;
 149 static __initdata unsigned long body_len, name_len;
 150 static __initdata uid_t uid;
 151 static __initdata gid_t gid;
 152 static __initdata unsigned rdev;
 153
 154 static void __init parse_header(char *s)
 155 {
 156         unsigned long parsed[12];
 157         char buf[9];
 158         int i;
 159
 160         buf[8] = '\0';
 161         for (i = 0, s += 6; i < 12; i++, s += 8) {
 162                 memcpy(buf, s, 8);
 163                 parsed[i] = simple_strtoul(buf, NULL, 16);
 164         }
 165         ino = parsed[0];
 166         mode = parsed[1];
 167         uid = parsed[2];
 168         gid = parsed[3];
 169         nlink = parsed[4];
 170         mtime = parsed[5]; /* breaks in y2106 */
 171         body_len = parsed[6];
 172         major = parsed[7];
 173         minor = parsed[8];
 174         rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
 175         name_len = parsed[11];
 176 }
 177
 178 /* FSM */
 179
 180 static __initdata enum state {
 181         Start,
 182         Collect,
 183         GotHeader,
 184         SkipIt,
 185         GotName,
 186         CopyFile,
 187         GotSymlink,
 188         Reset
 189 } state, next_state;
 190
 191 static __initdata char *victim;
 192 static unsigned long byte_count __initdata;
 193 static __initdata loff_t this_header, next_header;
 194
 195 static inline void __init eat(unsigned n)
 196 {
 197         victim += n;
 198         this_header += n;
 199         byte_count -= n;
 200 }
 201
 202 static __initdata char *vcollected;
 203 static __initdata char *collected;
 204 static long remains __initdata;
 205 static __initdata char *collect;
 206
 207 static void __init read_into(char *buf, unsigned size, enum state next)
 208 {
 209         if (byte_count >= size) {
 210                 collected = victim;
 211                 eat(size);
 212                 state = next;
 213         } else {
 214                 collect = collected = buf;
 215                 remains = size;
 216                 next_state = next;
 217                 state = Collect;
 218         }
 219 }
 220
 221 static __initdata char *header_buf, *symlink_buf, *name_buf;
 222
 223 static int __init do_start(void)
 224 {
 225         read_into(header_buf, 110, GotHeader);
 226         return 0;
 227 }
 228
 229 static int __init do_collect(void)
 230 {
 231         unsigned long n = remains;
 232         if (byte_count < n)
 233                 n = byte_count;
 234         memcpy(collect, victim, n);
 235         eat(n);
 236         collect += n;
 237         if ((remains -= n) != 0)
 238                 return 1;
 239         state = next_state;
 240         return 0;
 241 }
 242
 243 static int __init do_header(void)
 244 {
 245         if (memcmp(collected, "070707", 6)==0) {
 246                 error("incorrect cpio method used: use -H newc option");
 247                 return 1;
 248         }
 249         if (memcmp(collected, "070701", 6)) {
 250                 error("no cpio magic");
 251                 return 1;
 252         }
 253         parse_header(collected);
 254         next_header = this_header + N_ALIGN(name_len) + body_len;
 255         next_header = (next_header + 3) & ~3;
 256         state = SkipIt;
 257         if (name_len <= 0 || name_len > PATH_MAX)
 258                 return 0;
 259         if (S_ISLNK(mode)) {
 260                 if (body_len > PATH_MAX)
 261                         return 0;
 262                 collect = collected = symlink_buf;
 263                 remains = N_ALIGN(name_len) + body_len;
 264                 next_state = GotSymlink;
 265                 state = Collect;
 266                 return 0;
 267         }
 268         if (S_ISREG(mode) || !body_len)
 269                 read_into(name_buf, N_ALIGN(name_len), GotName);
 270         return 0;
 271 }
 272
 273 static int __init do_skip(void)
 274 {
 275         if (this_header + byte_count < next_header) {
 276                 eat(byte_count);
 277                 return 1;
 278         } else {
 279                 eat(next_header - this_header);
 280                 state = next_state;
 281                 return 0;
 282         }
 283 }
 284
 285 static int __init do_reset(void)
 286 {
 287         while (byte_count && *victim == '\0')
 288                 eat(1);
 289         if (byte_count && (this_header & 3))
 290                 error("broken padding");
 291         return 1;
 292 }
 293
 294 static void __init clean_path(char *path, umode_t fmode)
 295 {
 296         struct kstat st;
 297
 298         if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
 299                 if (S_ISDIR(st.mode))
 300                         ksys_rmdir(path);
 301                 else
 302                         ksys_unlink(path);
 303         }
 304 }
 305
 306 static int __init maybe_link(void)
 307 {
 308         if (nlink >= 2) {
 309                 char *old = find_link(major, minor, ino, mode, collected);
 310                 if (old) {
 311                         clean_path(collected, 0);
 312                         return (ksys_link(old, collected) < 0) ? -1 : 1;
 313                 }
 314         }
 315         return 0;
 316 }
 317
 318 static __initdata int wfd;
 319
 320 static int __init do_name(void)
 321 {
 322         state = SkipIt;
 323         next_state = Reset;
 324         if (strcmp(collected, "TRAILER!!!") == 0) {
 325                 free_hash();
 326                 return 0;
 327         }
 328         clean_path(collected, mode);
 329         if (S_ISREG(mode)) {
 330                 int ml = maybe_link();
 331                 if (ml >= 0) {
 332                         int openflags = O_WRONLY|O_CREAT;
 333                         if (ml != 1)
 334                                 openflags |= O_TRUNC;
 335                         wfd = ksys_open(collected, openflags, mode);
 336
 337                         if (wfd >= 0) {
 338                                 ksys_fchown(wfd, uid, gid);
 339                                 ksys_fchmod(wfd, mode);
 340                                 if (body_len)
 341                                         ksys_ftruncate(wfd, body_len);
 342                                 vcollected = kstrdup(collected, GFP_KERNEL);
 343                                 state = CopyFile;
 344                         }
 345                 }
 346         } else if (S_ISDIR(mode)) {
 347                 ksys_mkdir(collected, mode);
 348                 ksys_chown(collected, uid, gid);
 349                 ksys_chmod(collected, mode);
 350                 dir_add(collected, mtime);
 351         } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
 352                    S_ISFIFO(mode) || S_ISSOCK(mode)) {
 353                 if (maybe_link() == 0) {
 354                         ksys_mknod(collected, mode, rdev);
 355                         ksys_chown(collected, uid, gid);
 356                         ksys_chmod(collected, mode);
 357                         do_utime(collected, mtime);
 358                 }
 359         }
 360         return 0;
 361 }
 362
 363 static int __init do_copy(void)
 364 {
 365         if (byte_count >= body_len) {
 366                 if (xwrite(wfd, victim, body_len) != body_len)
 367                         error("write error");
 368                 ksys_close(wfd);
 369                 do_utime(vcollected, mtime);
 370                 kfree(vcollected);
 371                 eat(body_len);
 372                 state = SkipIt;
 373                 return 0;
 374         } else {
 375                 if (xwrite(wfd, victim, byte_count) != byte_count)
 376                         error("write error");
 377                 body_len -= byte_count;
 378                 eat(byte_count);
 379                 return 1;
 380         }
 381 }
 382
 383 static int __init do_symlink(void)
 384 {
 385         collected[N_ALIGN(name_len) + body_len] = '\0';
 386         clean_path(collected, 0);
 387         ksys_symlink(collected + N_ALIGN(name_len), collected);
 388         ksys_lchown(collected, uid, gid);
 389         do_utime(collected, mtime);
 390         state = SkipIt;
 391         next_state = Reset;
 392         return 0;
 393 }
 394
 395 static __initdata int (*actions[])(void) = {
 396         [Start]         = do_start,
 397         [Collect]       = do_collect,
 398         [GotHeader]     = do_header,
 399         [SkipIt]        = do_skip,
 400         [GotName]       = do_name,
 401         [CopyFile]      = do_copy,
 402         [GotSymlink]    = do_symlink,
 403         [Reset]         = do_reset,
 404 };
 405
 406 static long __init write_buffer(char *buf, unsigned long len)
 407 {
 408         byte_count = len;
 409         victim = buf;
 410
 411         while (!actions[state]())
 412                 ;
 413         return len - byte_count;
 414 }
 415
 416 static long __init flush_buffer(void *bufv, unsigned long len)
 417 {
 418         char *buf = (char *) bufv;
 419         long written;
 420         long origLen = len;
 421         if (message)
 422                 return -1;
 423         while ((written = write_buffer(buf, len)) < len && !message) {
 424                 char c = buf[written];
 425                 if (c == '0') {
 426                         buf += written;
 427                         len -= written;
 428                         state = Start;
 429                 } else if (c == 0) {
 430                         buf += written;
 431                         len -= written;
 432                         state = Reset;
 433                 } else
 434                         error("junk within compressed archive");
 435         }
 436         return origLen;
 437 }
 438
 439 static unsigned long my_inptr; /* index of next byte to be processed in inbuf */
 440
 441 #include <linux/decompress/generic.h>
 442
 443 static char * __init unpack_to_rootfs(char *buf, unsigned long len)
 444 {
 445         long written;
 446         decompress_fn decompress;
 447         const char *compress_name;
 448         static __initdata char msg_buf[64];
 449
 450         header_buf = kmalloc(110, GFP_KERNEL);
 451         symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
 452         name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
 453
 454         if (!header_buf || !symlink_buf || !name_buf)
 455                 panic("can't allocate buffers");
 456
 457         state = Start;
 458         this_header = 0;
 459         message = NULL;
 460         while (!message && len) {
 461                 loff_t saved_offset = this_header;
 462                 if (*buf == '0' && !(this_header & 3)) {
 463                         state = Start;
 464                         written = write_buffer(buf, len);
 465                         buf += written;
 466                         len -= written;
 467                         continue;
 468                 }
 469                 if (!*buf) {
 470                         buf++;
 471                         len--;
 472                         this_header++;
 473                         continue;
 474                 }
 475                 this_header = 0;
 476                 decompress = decompress_method(buf, len, &compress_name);
 477                 pr_debug("Detected %s compressed data\n", compress_name);
 478                 if (decompress) {
 479                         int res = decompress(buf, len, NULL, flush_buffer, NULL,
 480                                    &my_inptr, error);
 481                         if (res)
 482                                 error("decompressor failed");
 483                 } else if (compress_name) {
 484                         if (!message) {
 485                                 snprintf(msg_buf, sizeof msg_buf,
 486                                          "compression method %s not configured",
 487                                          compress_name);
 488                                 message = msg_buf;
 489                         }
 490                 } else
 491                         error("invalid magic at start of compressed archive");
 492                 if (state != Reset)
 493                         error("junk at the end of compressed archive");
 494                 this_header = saved_offset + my_inptr;
 495                 buf += my_inptr;
 496                 len -= my_inptr;
 497         }
 498         dir_utime();
 499         kfree(name_buf);
 500         kfree(symlink_buf);
 501         kfree(header_buf);
 502         return message;
 503 }
 504
 505 static int __initdata do_retain_initrd;
 506
 507 static int __init retain_initrd_param(char *str)
 508 {
 509         if (*str)
 510                 return 0;
 511         do_retain_initrd = 1;
 512         return 1;
 513 }
 514 __setup("retain_initrd", retain_initrd_param);
 515
 516 extern char __initramfs_start[];
 517 extern unsigned long __initramfs_size;
 518 #include <linux/initrd.h>
 519 #include <linux/kexec.h>
 520
 521 static void __init free_initrd(void)
 522 {
 523 #ifdef CONFIG_KEXEC_CORE
 524         unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
 525         unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
 526 #endif
 527         if (do_retain_initrd)
 528                 goto skip;
 529
 530 #ifdef CONFIG_KEXEC_CORE
 531         /*
 532          * If the initrd region is overlapped with crashkernel reserved region,
 533          * free only memory that is not part of crashkernel region.
 534          */
 535         if (initrd_start < crashk_end && initrd_end > crashk_start) {
 536                 /*
 537                  * Initialize initrd memory region since the kexec boot does
 538                  * not do.
 539                  */
 540                 memset((void *)initrd_start, 0, initrd_end - initrd_start);
 541                 if (initrd_start < crashk_start)
 542                         free_initrd_mem(initrd_start, crashk_start);
 543                 if (initrd_end > crashk_end)
 544                         free_initrd_mem(crashk_end, initrd_end);
 545         } else
 546 #endif
 547                 free_initrd_mem(initrd_start, initrd_end);
 548 skip:
 549         initrd_start = 0;
 550         initrd_end = 0;
 551 }
 552
 553 #ifdef CONFIG_BLK_DEV_RAM
 554 #define BUF_SIZE 1024
 555 static void __init clean_rootfs(void)
 556 {
 557         int fd;
 558         void *buf;
 559         struct linux_dirent64 *dirp;
 560         int num;
 561
 562         fd = ksys_open("/", O_RDONLY, 0);
 563         WARN_ON(fd < 0);
 564         if (fd < 0)
 565                 return;
 566         buf = kzalloc(BUF_SIZE, GFP_KERNEL);
 567         WARN_ON(!buf);
 568         if (!buf) {
 569                 ksys_close(fd);
 570                 return;
 571         }
 572
 573         dirp = buf;
 574         num = ksys_getdents64(fd, dirp, BUF_SIZE);
 575         while (num > 0) {
 576                 while (num > 0) {
 577                         struct kstat st;
 578                         int ret;
 579
 580                         ret = vfs_lstat(dirp->d_name, &st);
 581                         WARN_ON_ONCE(ret);
 582                         if (!ret) {
 583                                 if (S_ISDIR(st.mode))
 584                                         ksys_rmdir(dirp->d_name);
 585                                 else
 586                                         ksys_unlink(dirp->d_name);
 587                         }
 588
 589                         num -= dirp->d_reclen;
 590                         dirp = (void *)dirp + dirp->d_reclen;
 591                 }
 592                 dirp = buf;
 593                 memset(buf, 0, BUF_SIZE);
 594                 num = ksys_getdents64(fd, dirp, BUF_SIZE);
 595         }
 596
 597         ksys_close(fd);
 598         kfree(buf);
 599 }
 600 #endif
 601
 602 static int __init populate_rootfs(void)
 603 {
 604         /* Load the built in initramfs */
 605         char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
 606         if (err)
 607                 panic("%s", err); /* Failed to decompress INTERNAL initramfs */
 608         /* If available load the bootloader supplied initrd */
 609         if (initrd_start && !IS_ENABLED(CONFIG_INITRAMFS_FORCE)) {
 610 #ifdef CONFIG_BLK_DEV_RAM
 611                 int fd;
 612                 printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
 613                 err = unpack_to_rootfs((char *)initrd_start,
 614                         initrd_end - initrd_start);
 615                 if (!err) {
 616                         free_initrd();
 617                         goto done;
 618                 } else {
 619                         clean_rootfs();
 620                         unpack_to_rootfs(__initramfs_start, __initramfs_size);
 621                 }
 622                 printk(KERN_INFO "rootfs image is not initramfs (%s)"
 623                                 "; looks like an initrd\n", err);
 624                 fd = ksys_open("/initrd.image",
 625                               O_WRONLY|O_CREAT, 0700);
 626                 if (fd >= 0) {
 627                         ssize_t written = xwrite(fd, (char *)initrd_start,
 628                                                 initrd_end - initrd_start);
 629
 630                         if (written != initrd_end - initrd_start)
 631                                 pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
 632                                        written, initrd_end - initrd_start);
 633
 634                         ksys_close(fd);
 635                         free_initrd();
 636                 }
 637         done:
 638                 /* empty statement */;
 639 #else
 640                 printk(KERN_INFO "Unpacking initramfs...\n");
 641                 err = unpack_to_rootfs((char *)initrd_start,
 642                         initrd_end - initrd_start);
 643                 if (err)
 644                         printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 645                 free_initrd();
 646 #endif
 647         }
 648         flush_delayed_fput();
 649         return 0;
 650 }
 651 rootfs_initcall(populate_rootfs);