linux/init/initramfs.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Many of the syscalls used in this file expect some of the arguments
   4 * to be __user pointers not __kernel pointers.  To limit the sparse
   5 * noise, turn off sparse checking for this file.
   6 */
   7#ifdef __CHECKER__
   8#undef __CHECKER__
   9#warning "Sparse checking disabled for this file"
  10#endif
  11
  12#include <linux/init.h>
  13#include <linux/fs.h>
  14#include <linux/slab.h>
  15#include <linux/types.h>
  16#include <linux/fcntl.h>
  17#include <linux/delay.h>
  18#include <linux/string.h>
  19#include <linux/dirent.h>
  20#include <linux/syscalls.h>
  21#include <linux/utime.h>
  22#include <linux/file.h>
  23
  24static ssize_t __init xwrite(int fd, const char *p, size_t count)
  25{
  26        ssize_t out = 0;
  27
  28        /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
  29        while (count) {
  30                ssize_t rv = sys_write(fd, p, count);
  31
  32                if (rv < 0) {
  33                        if (rv == -EINTR || rv == -EAGAIN)
  34                                continue;
  35                        return out ? out : rv;
  36                } else if (rv == 0)
  37                        break;
  38
  39                p += rv;
  40                out += rv;
  41                count -= rv;
  42        }
  43
  44        return out;
  45}
  46
  47static __initdata char *message;
  48static void __init error(char *x)
  49{
  50        if (!message)
  51                message = x;
  52}
  53
  54/* link hash */
  55
  56#define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
  57
  58static __initdata struct hash {
  59        int ino, minor, major;
  60        umode_t mode;
  61        struct hash *next;
  62        char name[N_ALIGN(PATH_MAX)];
  63} *head[32];
  64
  65static inline int hash(int major, int minor, int ino)
  66{
  67        unsigned long tmp = ino + minor + (major << 3);
  68        tmp += tmp >> 5;
  69        return tmp & 31;
  70}
  71
  72static char __init *find_link(int major, int minor, int ino,
  73                              umode_t mode, char *name)
  74{
  75        struct hash **p, *q;
  76        for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
  77                if ((*p)->ino != ino)
  78                        continue;
  79                if ((*p)->minor != minor)
  80                        continue;
  81                if ((*p)->major != major)
  82                        continue;
  83                if (((*p)->mode ^ mode) & S_IFMT)
  84                        continue;
  85                return (*p)->name;
  86        }
  87        q = kmalloc(sizeof(struct hash), GFP_KERNEL);
  88        if (!q)
  89                panic("can't allocate link hash entry");
  90        q->major = major;
  91        q->minor = minor;
  92        q->ino = ino;
  93        q->mode = mode;
  94        strcpy(q->name, name);
  95        q->next = NULL;
  96        *p = q;
  97        return NULL;
  98}
  99
 100static void __init free_hash(void)
 101{
 102        struct hash **p, *q;
 103        for (p = head; p < head + 32; p++) {
 104                while (*p) {
 105                        q = *p;
 106                        *p = q->next;
 107                        kfree(q);
 108                }
 109        }
 110}
 111
 112static long __init do_utime(char *filename, time_t mtime)
 113{
 114        struct timespec64 t[2];
 115
 116        t[0].tv_sec = mtime;
 117        t[0].tv_nsec = 0;
 118        t[1].tv_sec = mtime;
 119        t[1].tv_nsec = 0;
 120
 121        return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
 122}
 123
 124static __initdata LIST_HEAD(dir_list);
 125struct dir_entry {
 126        struct list_head list;
 127        char *name;
 128        time_t mtime;
 129};
 130
 131static void __init dir_add(const char *name, time_t mtime)
 132{
 133        struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
 134        if (!de)
 135                panic("can't allocate dir_entry buffer");
 136        INIT_LIST_HEAD(&de->list);
 137        de->name = kstrdup(name, GFP_KERNEL);
 138        de->mtime = mtime;
 139        list_add(&de->list, &dir_list);
 140}
 141
 142static void __init dir_utime(void)
 143{
 144        struct dir_entry *de, *tmp;
 145        list_for_each_entry_safe(de, tmp, &dir_list, list) {
 146                list_del(&de->list);
 147                do_utime(de->name, de->mtime);
 148                kfree(de->name);
 149                kfree(de);
 150        }
 151}
 152
 153static __initdata time_t mtime;
 154
 155/* cpio header parsing */
 156
 157static __initdata unsigned long ino, major, minor, nlink;
 158static __initdata umode_t mode;
 159static __initdata unsigned long body_len, name_len;
 160static __initdata uid_t uid;
 161static __initdata gid_t gid;
 162static __initdata unsigned rdev;
 163
 164static void __init parse_header(char *s)
 165{
 166        unsigned long parsed[12];
 167        char buf[9];
 168        int i;
 169
 170        buf[8] = '\0';
 171        for (i = 0, s += 6; i < 12; i++, s += 8) {
 172                memcpy(buf, s, 8);
 173                parsed[i] = simple_strtoul(buf, NULL, 16);
 174        }
 175        ino = parsed[0];
 176        mode = parsed[1];
 177        uid = parsed[2];
 178        gid = parsed[3];
 179        nlink = parsed[4];
 180        mtime = parsed[5];
 181        body_len = parsed[6];
 182        major = parsed[7];
 183        minor = parsed[8];
 184        rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
 185        name_len = parsed[11];
 186}
 187
 188/* FSM */
 189
 190static __initdata enum state {
 191        Start,
 192        Collect,
 193        GotHeader,
 194        SkipIt,
 195        GotName,
 196        CopyFile,
 197        GotSymlink,
 198        Reset
 199} state, next_state;
 200
 201static __initdata char *victim;
 202static unsigned long byte_count __initdata;
 203static __initdata loff_t this_header, next_header;
 204
 205static inline void __init eat(unsigned n)
 206{
 207        victim += n;
 208        this_header += n;
 209        byte_count -= n;
 210}
 211
 212static __initdata char *vcollected;
 213static __initdata char *collected;
 214static long remains __initdata;
 215static __initdata char *collect;
 216
 217static void __init read_into(char *buf, unsigned size, enum state next)
 218{
 219        if (byte_count >= size) {
 220                collected = victim;
 221                eat(size);
 222                state = next;
 223        } else {
 224                collect = collected = buf;
 225                remains = size;
 226                next_state = next;
 227                state = Collect;
 228        }
 229}
 230
 231static __initdata char *header_buf, *symlink_buf, *name_buf;
 232
 233static int __init do_start(void)
 234{
 235        read_into(header_buf, 110, GotHeader);
 236        return 0;
 237}
 238
 239static int __init do_collect(void)
 240{
 241        unsigned long n = remains;
 242        if (byte_count < n)
 243                n = byte_count;
 244        memcpy(collect, victim, n);
 245        eat(n);
 246        collect += n;
 247        if ((remains -= n) != 0)
 248                return 1;
 249        state = next_state;
 250        return 0;
 251}
 252
 253static int __init do_header(void)
 254{
 255        if (memcmp(collected, "070707", 6)==0) {
 256                error("incorrect cpio method used: use -H newc option");
 257                return 1;
 258        }
 259        if (memcmp(collected, "070701", 6)) {
 260                error("no cpio magic");
 261                return 1;
 262        }
 263        parse_header(collected);
 264        next_header = this_header + N_ALIGN(name_len) + body_len;
 265        next_header = (next_header + 3) & ~3;
 266        state = SkipIt;
 267        if (name_len <= 0 || name_len > PATH_MAX)
 268                return 0;
 269        if (S_ISLNK(mode)) {
 270                if (body_len > PATH_MAX)
 271                        return 0;
 272                collect = collected = symlink_buf;
 273                remains = N_ALIGN(name_len) + body_len;
 274                next_state = GotSymlink;
 275                state = Collect;
 276                return 0;
 277        }
 278        if (S_ISREG(mode) || !body_len)
 279                read_into(name_buf, N_ALIGN(name_len), GotName);
 280        return 0;
 281}
 282
 283static int __init do_skip(void)
 284{
 285        if (this_header + byte_count < next_header) {
 286                eat(byte_count);
 287                return 1;
 288        } else {
 289                eat(next_header - this_header);
 290                state = next_state;
 291                return 0;
 292        }
 293}
 294
 295static int __init do_reset(void)
 296{
 297        while (byte_count && *victim == '\0')
 298                eat(1);
 299        if (byte_count && (this_header & 3))
 300                error("broken padding");
 301        return 1;
 302}
 303
 304static int __init maybe_link(void)
 305{
 306        if (nlink >= 2) {
 307                char *old = find_link(major, minor, ino, mode, collected);
 308                if (old)
 309                        return (sys_link(old, collected) < 0) ? -1 : 1;
 310        }
 311        return 0;
 312}
 313
 314static void __init clean_path(char *path, umode_t fmode)
 315{
 316        struct kstat st;
 317
 318        if (!vfs_lstat(path, &st) && (st.mode ^ fmode) & S_IFMT) {
 319                if (S_ISDIR(st.mode))
 320                        sys_rmdir(path);
 321                else
 322                        sys_unlink(path);
 323        }
 324}
 325
 326static __initdata int wfd;
 327
 328static int __init do_name(void)
 329{
 330        state = SkipIt;
 331        next_state = Reset;
 332        if (strcmp(collected, "TRAILER!!!") == 0) {
 333                free_hash();
 334                return 0;
 335        }
 336        clean_path(collected, mode);
 337        if (S_ISREG(mode)) {
 338                int ml = maybe_link();
 339                if (ml >= 0) {
 340                        int openflags = O_WRONLY|O_CREAT;
 341                        if (ml != 1)
 342                                openflags |= O_TRUNC;
 343                        wfd = sys_open(collected, openflags, mode);
 344
 345                        if (wfd >= 0) {
 346                                sys_fchown(wfd, uid, gid);
 347                                sys_fchmod(wfd, mode);
 348                                if (body_len)
 349                                        sys_ftruncate(wfd, body_len);
 350                                vcollected = kstrdup(collected, GFP_KERNEL);
 351                                state = CopyFile;
 352                        }
 353                }
 354        } else if (S_ISDIR(mode)) {
 355                sys_mkdir(collected, mode);
 356                sys_chown(collected, uid, gid);
 357                sys_chmod(collected, mode);
 358                dir_add(collected, mtime);
 359        } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
 360                   S_ISFIFO(mode) || S_ISSOCK(mode)) {
 361                if (maybe_link() == 0) {
 362                        sys_mknod(collected, mode, rdev);
 363                        sys_chown(collected, uid, gid);
 364                        sys_chmod(collected, mode);
 365                        do_utime(collected, mtime);
 366                }
 367        }
 368        return 0;
 369}
 370
 371static int __init do_copy(void)
 372{
 373        if (byte_count >= body_len) {
 374                if (xwrite(wfd, victim, body_len) != body_len)
 375                        error("write error");
 376                sys_close(wfd);
 377                do_utime(vcollected, mtime);
 378                kfree(vcollected);
 379                eat(body_len);
 380                state = SkipIt;
 381                return 0;
 382        } else {
 383                if (xwrite(wfd, victim, byte_count) != byte_count)
 384                        error("write error");
 385                body_len -= byte_count;
 386                eat(byte_count);
 387                return 1;
 388        }
 389}
 390
 391static int __init do_symlink(void)
 392{
 393        collected[N_ALIGN(name_len) + body_len] = '\0';
 394        clean_path(collected, 0);
 395        sys_symlink(collected + N_ALIGN(name_len), collected);
 396        sys_lchown(collected, uid, gid);
 397        do_utime(collected, mtime);
 398        state = SkipIt;
 399        next_state = Reset;
 400        return 0;
 401}
 402
 403static __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
 414static 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
 424static 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 in compressed archive");
 443        }
 444        return origLen;
 445}
 446
 447static unsigned long my_inptr; /* index of next byte to be processed in inbuf */
 448
 449#include <linux/decompress/generic.h>
 450
 451static 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("junk in compressed archive");
 500                if (state != Reset)
 501                        error("junk in 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
 513static int __initdata do_retain_initrd;
 514
 515static 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
 524extern char __initramfs_start[];
 525extern unsigned long __initramfs_size;
 526#include <linux/initrd.h>
 527#include <linux/kexec.h>
 528
 529static void __init free_initrd(void)
 530{
 531#ifdef CONFIG_KEXEC_CORE
 532        unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
 533        unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
 534#endif
 535        if (do_retain_initrd)
 536                goto skip;
 537
 538#ifdef CONFIG_KEXEC_CORE
 539        /*
 540         * If the initrd region is overlapped with crashkernel reserved region,
 541         * free only memory that is not part of crashkernel region.
 542         */
 543        if (initrd_start < crashk_end && initrd_end > crashk_start) {
 544                /*
 545                 * Initialize initrd memory region since the kexec boot does
 546                 * not do.
 547                 */
 548                memset((void *)initrd_start, 0, initrd_end - initrd_start);
 549                if (initrd_start < crashk_start)
 550                        free_initrd_mem(initrd_start, crashk_start);
 551                if (initrd_end > crashk_end)
 552                        free_initrd_mem(crashk_end, initrd_end);
 553        } else
 554#endif
 555                free_initrd_mem(initrd_start, initrd_end);
 556skip:
 557        initrd_start = 0;
 558        initrd_end = 0;
 559}
 560
 561#ifdef CONFIG_BLK_DEV_RAM
 562#define BUF_SIZE 1024
 563static void __init clean_rootfs(void)
 564{
 565        int fd;
 566        void *buf;
 567        struct linux_dirent64 *dirp;
 568        int num;
 569
 570        fd = sys_open("/", O_RDONLY, 0);
 571        WARN_ON(fd < 0);
 572        if (fd < 0)
 573                return;
 574        buf = kzalloc(BUF_SIZE, GFP_KERNEL);
 575        WARN_ON(!buf);
 576        if (!buf) {
 577                sys_close(fd);
 578                return;
 579        }
 580
 581        dirp = buf;
 582        num = sys_getdents64(fd, dirp, BUF_SIZE);
 583        while (num > 0) {
 584                while (num > 0) {
 585                        struct kstat st;
 586                        int ret;
 587
 588                        ret = vfs_lstat(dirp->d_name, &st);
 589                        WARN_ON_ONCE(ret);
 590                        if (!ret) {
 591                                if (S_ISDIR(st.mode))
 592                                        sys_rmdir(dirp->d_name);
 593                                else
 594                                        sys_unlink(dirp->d_name);
 595                        }
 596
 597                        num -= dirp->d_reclen;
 598                        dirp = (void *)dirp + dirp->d_reclen;
 599                }
 600                dirp = buf;
 601                memset(buf, 0, BUF_SIZE);
 602                num = sys_getdents64(fd, dirp, BUF_SIZE);
 603        }
 604
 605        sys_close(fd);
 606        kfree(buf);
 607}
 608#endif
 609
 610static int __init populate_rootfs(void)
 611{
 612        /* Load the built in initramfs */
 613        char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
 614        if (err)
 615                panic("%s", err); /* Failed to decompress INTERNAL initramfs */
 616        /* If available load the bootloader supplied initrd */
 617        if (initrd_start && !IS_ENABLED(CONFIG_INITRAMFS_FORCE)) {
 618#ifdef CONFIG_BLK_DEV_RAM
 619                int fd;
 620                printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
 621                err = unpack_to_rootfs((char *)initrd_start,
 622                        initrd_end - initrd_start);
 623                if (!err) {
 624                        free_initrd();
 625                        goto done;
 626                } else {
 627                        clean_rootfs();
 628                        unpack_to_rootfs(__initramfs_start, __initramfs_size);
 629                }
 630                printk(KERN_INFO "rootfs image is not initramfs (%s)"
 631                                "; looks like an initrd\n", err);
 632                fd = sys_open("/initrd.image",
 633                              O_WRONLY|O_CREAT, 0700);
 634                if (fd >= 0) {
 635                        ssize_t written = xwrite(fd, (char *)initrd_start,
 636                                                initrd_end - initrd_start);
 637
 638                        if (written != initrd_end - initrd_start)
 639                                pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
 640                                       written, initrd_end - initrd_start);
 641
 642                        sys_close(fd);
 643                        free_initrd();
 644                }
 645        done:
 646                /* empty statement */;
 647#else
 648                printk(KERN_INFO "Unpacking initramfs...\n");
 649                err = unpack_to_rootfs((char *)initrd_start,
 650                        initrd_end - initrd_start);
 651                if (err)
 652                        printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
 653                free_initrd();
 654#endif
 655        }
 656        flush_delayed_fput();
 657        /*
 658         * Try loading default modules from initramfs.  This gives
 659         * us a chance to load before device_initcalls.
 660         */
 661        load_default_modules();
 662
 663        return 0;
 664}
 665rootfs_initcall(populate_rootfs);
 666