linux/init/initramfs.c
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   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
  14static 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
  37static __initdata char *message;
  38static 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
  48static __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
  55static 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
  62static 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
  90static 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
 102static 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
 114static __initdata LIST_HEAD(dir_list);
 115struct dir_entry {
 116        struct list_head list;
 117        char *name;
 118        time64_t mtime;
 119};
 120
 121static 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
 132static 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
 143static __initdata time64_t mtime;
 144
 145/* cpio header parsing */
 146
 147static __initdata unsigned long ino, major, minor, nlink;
 148static __initdata umode_t mode;
 149static __initdata unsigned long body_len, name_len;
 150static __initdata uid_t uid;
 151static __initdata gid_t gid;
 152static __initdata unsigned rdev;
 153
 154static 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
 180static __initdata enum state {
 181        Start,
 182        Collect,
 183        GotHeader,
 184        SkipIt,
 185        GotName,
 186        CopyFile,
 187        GotSymlink,
 188        Reset
 189} state, next_state;
 190
 191static __initdata char *victim;
 192static unsigned long byte_count __initdata;
 193static __initdata loff_t this_header, next_header;
 194
 195static inline void __init eat(unsigned n)
 196{
 197        victim += n;
 198        this_header += n;
 199        byte_count -= n;
 200}
 201
 202static __initdata char *vcollected;
 203static __initdata char *collected;
 204static long remains __initdata;
 205static __initdata char *collect;
 206
 207static 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
 221static __initdata char *header_buf, *symlink_buf, *name_buf;
 222
 223static int __init do_start(void)
 224{
 225        read_into(header_buf, 110, GotHeader);
 226        return 0;
 227}
 228
 229static 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
 243static 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
 273static 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
 285static 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
 294static 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
 306static 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
 318static __initdata int wfd;
 319
 320static 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
 363static 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
 383static 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
 395static __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
 406static 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
 416static 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 in compressed archive");
 435        }
 436        return origLen;
 437}
 438
 439static unsigned long my_inptr; /* index of next byte to be processed in inbuf */
 440
 441#include <linux/decompress/generic.h>
 442
 443static 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("junk in compressed archive");
 492                if (state != Reset)
 493                        error("junk in 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
 505static int __initdata do_retain_initrd;
 506
 507static 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
 516extern char __initramfs_start[];
 517extern unsigned long __initramfs_size;
 518#include <linux/initrd.h>
 519#include <linux/kexec.h>
 520
 521static 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);
 548skip:
 549        initrd_start = 0;
 550        initrd_end = 0;
 551}
 552
 553#ifdef CONFIG_BLK_DEV_RAM
 554#define BUF_SIZE 1024
 555static 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
 602static 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        /*
 650         * Try loading default modules from initramfs.  This gives
 651         * us a chance to load before device_initcalls.
 652         */
 653        load_default_modules();
 654
 655        return 0;
 656}
 657rootfs_initcall(populate_rootfs);
 658