linux/fs/ubifs/master.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * This file is part of UBIFS.
   4 *
   5 * Copyright (C) 2006-2008 Nokia Corporation.
   6 *
   7 * Authors: Artem Bityutskiy (Битюцкий Артём)
   8 *          Adrian Hunter
   9 */
  10
  11/* This file implements reading and writing the master node */
  12
  13#include "ubifs.h"
  14
  15/**
  16 * ubifs_compare_master_node - compare two UBIFS master nodes
  17 * @c: UBIFS file-system description object
  18 * @m1: the first node
  19 * @m2: the second node
  20 *
  21 * This function compares two UBIFS master nodes. Returns 0 if they are equal
  22 * and nonzero if not.
  23 */
  24int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
  25{
  26        int ret;
  27        int behind;
  28        int hmac_offs = offsetof(struct ubifs_mst_node, hmac);
  29
  30        /*
  31         * Do not compare the common node header since the sequence number and
  32         * hence the CRC are different.
  33         */
  34        ret = memcmp(m1 + UBIFS_CH_SZ, m2 + UBIFS_CH_SZ,
  35                     hmac_offs - UBIFS_CH_SZ);
  36        if (ret)
  37                return ret;
  38
  39        /*
  40         * Do not compare the embedded HMAC aswell which also must be different
  41         * due to the different common node header.
  42         */
  43        behind = hmac_offs + UBIFS_MAX_HMAC_LEN;
  44
  45        if (UBIFS_MST_NODE_SZ > behind)
  46                return memcmp(m1 + behind, m2 + behind, UBIFS_MST_NODE_SZ - behind);
  47
  48        return 0;
  49}
  50
  51/* mst_node_check_hash - Check hash of a master node
  52 * @c: UBIFS file-system description object
  53 * @mst: The master node
  54 * @expected: The expected hash of the master node
  55 *
  56 * This checks the hash of a master node against a given expected hash.
  57 * Note that we have two master nodes on a UBIFS image which have different
  58 * sequence numbers and consequently different CRCs. To be able to match
  59 * both master nodes we exclude the common node header containing the sequence
  60 * number and CRC from the hash.
  61 *
  62 * Returns 0 if the hashes are equal, a negative error code otherwise.
  63 */
  64static int mst_node_check_hash(const struct ubifs_info *c,
  65                               const struct ubifs_mst_node *mst,
  66                               const u8 *expected)
  67{
  68        u8 calc[UBIFS_MAX_HASH_LEN];
  69        const void *node = mst;
  70
  71        crypto_shash_tfm_digest(c->hash_tfm, node + sizeof(struct ubifs_ch),
  72                                UBIFS_MST_NODE_SZ - sizeof(struct ubifs_ch),
  73                                calc);
  74
  75        if (ubifs_check_hash(c, expected, calc))
  76                return -EPERM;
  77
  78        return 0;
  79}
  80
  81/**
  82 * scan_for_master - search the valid master node.
  83 * @c: UBIFS file-system description object
  84 *
  85 * This function scans the master node LEBs and search for the latest master
  86 * node. Returns zero in case of success, %-EUCLEAN if there master area is
  87 * corrupted and requires recovery, and a negative error code in case of
  88 * failure.
  89 */
  90static int scan_for_master(struct ubifs_info *c)
  91{
  92        struct ubifs_scan_leb *sleb;
  93        struct ubifs_scan_node *snod;
  94        int lnum, offs = 0, nodes_cnt, err;
  95
  96        lnum = UBIFS_MST_LNUM;
  97
  98        sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
  99        if (IS_ERR(sleb))
 100                return PTR_ERR(sleb);
 101        nodes_cnt = sleb->nodes_cnt;
 102        if (nodes_cnt > 0) {
 103                snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
 104                                  list);
 105                if (snod->type != UBIFS_MST_NODE)
 106                        goto out_dump;
 107                memcpy(c->mst_node, snod->node, snod->len);
 108                offs = snod->offs;
 109        }
 110        ubifs_scan_destroy(sleb);
 111
 112        lnum += 1;
 113
 114        sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
 115        if (IS_ERR(sleb))
 116                return PTR_ERR(sleb);
 117        if (sleb->nodes_cnt != nodes_cnt)
 118                goto out;
 119        if (!sleb->nodes_cnt)
 120                goto out;
 121        snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node, list);
 122        if (snod->type != UBIFS_MST_NODE)
 123                goto out_dump;
 124        if (snod->offs != offs)
 125                goto out;
 126        if (ubifs_compare_master_node(c, c->mst_node, snod->node))
 127                goto out;
 128
 129        c->mst_offs = offs;
 130        ubifs_scan_destroy(sleb);
 131
 132        if (!ubifs_authenticated(c))
 133                return 0;
 134
 135        if (ubifs_hmac_zero(c, c->mst_node->hmac)) {
 136                err = mst_node_check_hash(c, c->mst_node,
 137                                          c->sup_node->hash_mst);
 138                if (err)
 139                        ubifs_err(c, "Failed to verify master node hash");
 140        } else {
 141                err = ubifs_node_verify_hmac(c, c->mst_node,
 142                                        sizeof(struct ubifs_mst_node),
 143                                        offsetof(struct ubifs_mst_node, hmac));
 144                if (err)
 145                        ubifs_err(c, "Failed to verify master node HMAC");
 146        }
 147
 148        if (err)
 149                return -EPERM;
 150
 151        return 0;
 152
 153out:
 154        ubifs_scan_destroy(sleb);
 155        return -EUCLEAN;
 156
 157out_dump:
 158        ubifs_err(c, "unexpected node type %d master LEB %d:%d",
 159                  snod->type, lnum, snod->offs);
 160        ubifs_scan_destroy(sleb);
 161        return -EINVAL;
 162}
 163
 164/**
 165 * validate_master - validate master node.
 166 * @c: UBIFS file-system description object
 167 *
 168 * This function validates data which was read from master node. Returns zero
 169 * if the data is all right and %-EINVAL if not.
 170 */
 171static int validate_master(const struct ubifs_info *c)
 172{
 173        long long main_sz;
 174        int err;
 175
 176        if (c->max_sqnum >= SQNUM_WATERMARK) {
 177                err = 1;
 178                goto out;
 179        }
 180
 181        if (c->cmt_no >= c->max_sqnum) {
 182                err = 2;
 183                goto out;
 184        }
 185
 186        if (c->highest_inum >= INUM_WATERMARK) {
 187                err = 3;
 188                goto out;
 189        }
 190
 191        if (c->lhead_lnum < UBIFS_LOG_LNUM ||
 192            c->lhead_lnum >= UBIFS_LOG_LNUM + c->log_lebs ||
 193            c->lhead_offs < 0 || c->lhead_offs >= c->leb_size ||
 194            c->lhead_offs & (c->min_io_size - 1)) {
 195                err = 4;
 196                goto out;
 197        }
 198
 199        if (c->zroot.lnum >= c->leb_cnt || c->zroot.lnum < c->main_first ||
 200            c->zroot.offs >= c->leb_size || c->zroot.offs & 7) {
 201                err = 5;
 202                goto out;
 203        }
 204
 205        if (c->zroot.len < c->ranges[UBIFS_IDX_NODE].min_len ||
 206            c->zroot.len > c->ranges[UBIFS_IDX_NODE].max_len) {
 207                err = 6;
 208                goto out;
 209        }
 210
 211        if (c->gc_lnum >= c->leb_cnt || c->gc_lnum < c->main_first) {
 212                err = 7;
 213                goto out;
 214        }
 215
 216        if (c->ihead_lnum >= c->leb_cnt || c->ihead_lnum < c->main_first ||
 217            c->ihead_offs % c->min_io_size || c->ihead_offs < 0 ||
 218            c->ihead_offs > c->leb_size || c->ihead_offs & 7) {
 219                err = 8;
 220                goto out;
 221        }
 222
 223        main_sz = (long long)c->main_lebs * c->leb_size;
 224        if (c->bi.old_idx_sz & 7 || c->bi.old_idx_sz >= main_sz) {
 225                err = 9;
 226                goto out;
 227        }
 228
 229        if (c->lpt_lnum < c->lpt_first || c->lpt_lnum > c->lpt_last ||
 230            c->lpt_offs < 0 || c->lpt_offs + c->nnode_sz > c->leb_size) {
 231                err = 10;
 232                goto out;
 233        }
 234
 235        if (c->nhead_lnum < c->lpt_first || c->nhead_lnum > c->lpt_last ||
 236            c->nhead_offs < 0 || c->nhead_offs % c->min_io_size ||
 237            c->nhead_offs > c->leb_size) {
 238                err = 11;
 239                goto out;
 240        }
 241
 242        if (c->ltab_lnum < c->lpt_first || c->ltab_lnum > c->lpt_last ||
 243            c->ltab_offs < 0 ||
 244            c->ltab_offs + c->ltab_sz > c->leb_size) {
 245                err = 12;
 246                goto out;
 247        }
 248
 249        if (c->big_lpt && (c->lsave_lnum < c->lpt_first ||
 250            c->lsave_lnum > c->lpt_last || c->lsave_offs < 0 ||
 251            c->lsave_offs + c->lsave_sz > c->leb_size)) {
 252                err = 13;
 253                goto out;
 254        }
 255
 256        if (c->lscan_lnum < c->main_first || c->lscan_lnum >= c->leb_cnt) {
 257                err = 14;
 258                goto out;
 259        }
 260
 261        if (c->lst.empty_lebs < 0 || c->lst.empty_lebs > c->main_lebs - 2) {
 262                err = 15;
 263                goto out;
 264        }
 265
 266        if (c->lst.idx_lebs < 0 || c->lst.idx_lebs > c->main_lebs - 1) {
 267                err = 16;
 268                goto out;
 269        }
 270
 271        if (c->lst.total_free < 0 || c->lst.total_free > main_sz ||
 272            c->lst.total_free & 7) {
 273                err = 17;
 274                goto out;
 275        }
 276
 277        if (c->lst.total_dirty < 0 || (c->lst.total_dirty & 7)) {
 278                err = 18;
 279                goto out;
 280        }
 281
 282        if (c->lst.total_used < 0 || (c->lst.total_used & 7)) {
 283                err = 19;
 284                goto out;
 285        }
 286
 287        if (c->lst.total_free + c->lst.total_dirty +
 288            c->lst.total_used > main_sz) {
 289                err = 20;
 290                goto out;
 291        }
 292
 293        if (c->lst.total_dead + c->lst.total_dark +
 294            c->lst.total_used + c->bi.old_idx_sz > main_sz) {
 295                err = 21;
 296                goto out;
 297        }
 298
 299        if (c->lst.total_dead < 0 ||
 300            c->lst.total_dead > c->lst.total_free + c->lst.total_dirty ||
 301            c->lst.total_dead & 7) {
 302                err = 22;
 303                goto out;
 304        }
 305
 306        if (c->lst.total_dark < 0 ||
 307            c->lst.total_dark > c->lst.total_free + c->lst.total_dirty ||
 308            c->lst.total_dark & 7) {
 309                err = 23;
 310                goto out;
 311        }
 312
 313        return 0;
 314
 315out:
 316        ubifs_err(c, "bad master node at offset %d error %d", c->mst_offs, err);
 317        ubifs_dump_node(c, c->mst_node);
 318        return -EINVAL;
 319}
 320
 321/**
 322 * ubifs_read_master - read master node.
 323 * @c: UBIFS file-system description object
 324 *
 325 * This function finds and reads the master node during file-system mount. If
 326 * the flash is empty, it creates default master node as well. Returns zero in
 327 * case of success and a negative error code in case of failure.
 328 */
 329int ubifs_read_master(struct ubifs_info *c)
 330{
 331        int err, old_leb_cnt;
 332
 333        c->mst_node = kzalloc(c->mst_node_alsz, GFP_KERNEL);
 334        if (!c->mst_node)
 335                return -ENOMEM;
 336
 337        err = scan_for_master(c);
 338        if (err) {
 339                if (err == -EUCLEAN)
 340                        err = ubifs_recover_master_node(c);
 341                if (err)
 342                        /*
 343                         * Note, we do not free 'c->mst_node' here because the
 344                         * unmount routine will take care of this.
 345                         */
 346                        return err;
 347        }
 348
 349        /* Make sure that the recovery flag is clear */
 350        c->mst_node->flags &= cpu_to_le32(~UBIFS_MST_RCVRY);
 351
 352        c->max_sqnum       = le64_to_cpu(c->mst_node->ch.sqnum);
 353        c->highest_inum    = le64_to_cpu(c->mst_node->highest_inum);
 354        c->cmt_no          = le64_to_cpu(c->mst_node->cmt_no);
 355        c->zroot.lnum      = le32_to_cpu(c->mst_node->root_lnum);
 356        c->zroot.offs      = le32_to_cpu(c->mst_node->root_offs);
 357        c->zroot.len       = le32_to_cpu(c->mst_node->root_len);
 358        c->lhead_lnum      = le32_to_cpu(c->mst_node->log_lnum);
 359        c->gc_lnum         = le32_to_cpu(c->mst_node->gc_lnum);
 360        c->ihead_lnum      = le32_to_cpu(c->mst_node->ihead_lnum);
 361        c->ihead_offs      = le32_to_cpu(c->mst_node->ihead_offs);
 362        c->bi.old_idx_sz   = le64_to_cpu(c->mst_node->index_size);
 363        c->lpt_lnum        = le32_to_cpu(c->mst_node->lpt_lnum);
 364        c->lpt_offs        = le32_to_cpu(c->mst_node->lpt_offs);
 365        c->nhead_lnum      = le32_to_cpu(c->mst_node->nhead_lnum);
 366        c->nhead_offs      = le32_to_cpu(c->mst_node->nhead_offs);
 367        c->ltab_lnum       = le32_to_cpu(c->mst_node->ltab_lnum);
 368        c->ltab_offs       = le32_to_cpu(c->mst_node->ltab_offs);
 369        c->lsave_lnum      = le32_to_cpu(c->mst_node->lsave_lnum);
 370        c->lsave_offs      = le32_to_cpu(c->mst_node->lsave_offs);
 371        c->lscan_lnum      = le32_to_cpu(c->mst_node->lscan_lnum);
 372        c->lst.empty_lebs  = le32_to_cpu(c->mst_node->empty_lebs);
 373        c->lst.idx_lebs    = le32_to_cpu(c->mst_node->idx_lebs);
 374        old_leb_cnt        = le32_to_cpu(c->mst_node->leb_cnt);
 375        c->lst.total_free  = le64_to_cpu(c->mst_node->total_free);
 376        c->lst.total_dirty = le64_to_cpu(c->mst_node->total_dirty);
 377        c->lst.total_used  = le64_to_cpu(c->mst_node->total_used);
 378        c->lst.total_dead  = le64_to_cpu(c->mst_node->total_dead);
 379        c->lst.total_dark  = le64_to_cpu(c->mst_node->total_dark);
 380
 381        ubifs_copy_hash(c, c->mst_node->hash_root_idx, c->zroot.hash);
 382
 383        c->calc_idx_sz = c->bi.old_idx_sz;
 384
 385        if (c->mst_node->flags & cpu_to_le32(UBIFS_MST_NO_ORPHS))
 386                c->no_orphs = 1;
 387
 388        if (old_leb_cnt != c->leb_cnt) {
 389                /* The file system has been resized */
 390                int growth = c->leb_cnt - old_leb_cnt;
 391
 392                if (c->leb_cnt < old_leb_cnt ||
 393                    c->leb_cnt < UBIFS_MIN_LEB_CNT) {
 394                        ubifs_err(c, "bad leb_cnt on master node");
 395                        ubifs_dump_node(c, c->mst_node);
 396                        return -EINVAL;
 397                }
 398
 399                dbg_mnt("Auto resizing (master) from %d LEBs to %d LEBs",
 400                        old_leb_cnt, c->leb_cnt);
 401                c->lst.empty_lebs += growth;
 402                c->lst.total_free += growth * (long long)c->leb_size;
 403                c->lst.total_dark += growth * (long long)c->dark_wm;
 404
 405                /*
 406                 * Reflect changes back onto the master node. N.B. the master
 407                 * node gets written immediately whenever mounting (or
 408                 * remounting) in read-write mode, so we do not need to write it
 409                 * here.
 410                 */
 411                c->mst_node->leb_cnt = cpu_to_le32(c->leb_cnt);
 412                c->mst_node->empty_lebs = cpu_to_le32(c->lst.empty_lebs);
 413                c->mst_node->total_free = cpu_to_le64(c->lst.total_free);
 414                c->mst_node->total_dark = cpu_to_le64(c->lst.total_dark);
 415        }
 416
 417        err = validate_master(c);
 418        if (err)
 419                return err;
 420
 421        err = dbg_old_index_check_init(c, &c->zroot);
 422
 423        return err;
 424}
 425
 426/**
 427 * ubifs_write_master - write master node.
 428 * @c: UBIFS file-system description object
 429 *
 430 * This function writes the master node. Returns zero in case of success and a
 431 * negative error code in case of failure. The master node is written twice to
 432 * enable recovery.
 433 */
 434int ubifs_write_master(struct ubifs_info *c)
 435{
 436        int err, lnum, offs, len;
 437
 438        ubifs_assert(c, !c->ro_media && !c->ro_mount);
 439        if (c->ro_error)
 440                return -EROFS;
 441
 442        lnum = UBIFS_MST_LNUM;
 443        offs = c->mst_offs + c->mst_node_alsz;
 444        len = UBIFS_MST_NODE_SZ;
 445
 446        if (offs + UBIFS_MST_NODE_SZ > c->leb_size) {
 447                err = ubifs_leb_unmap(c, lnum);
 448                if (err)
 449                        return err;
 450                offs = 0;
 451        }
 452
 453        c->mst_offs = offs;
 454        c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);
 455
 456        ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);
 457        err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
 458                                    offsetof(struct ubifs_mst_node, hmac));
 459        if (err)
 460                return err;
 461
 462        lnum += 1;
 463
 464        if (offs == 0) {
 465                err = ubifs_leb_unmap(c, lnum);
 466                if (err)
 467                        return err;
 468        }
 469        err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
 470                                    offsetof(struct ubifs_mst_node, hmac));
 471
 472        return err;
 473}
 474