// SPDX-License-Identifier: GPL-2.0-only
/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/* This file implements reading and writing the master node */

#include "ubifs.h"

/**
 * ubifs_compare_master_node - compare two UBIFS master nodes
 * @c: UBIFS file-system description object
 * @m1: the first node
 * @m2: the second node
 *
 * This function compares two UBIFS master nodes. Returns 0 if they are equal
 * and nonzero if not.
 */
int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
{
        int ret;
        int behind;
        int hmac_offs = offsetof(struct ubifs_mst_node, hmac);

        /*
         * Do not compare the common node header since the sequence number and
         * hence the CRC are different.
         */
        ret = memcmp(m1 + UBIFS_CH_SZ, m2 + UBIFS_CH_SZ,
                     hmac_offs - UBIFS_CH_SZ);
        if (ret)
                return ret;

        /*
         * Do not compare the embedded HMAC as well which also must be different
         * due to the different common node header.
         */
        behind = hmac_offs + UBIFS_MAX_HMAC_LEN;

        if (UBIFS_MST_NODE_SZ > behind)
                return memcmp(m1 + behind, m2 + behind, UBIFS_MST_NODE_SZ - behind);

        return 0;
}

/* mst_node_check_hash - Check hash of a master node
 * @c: UBIFS file-system description object
 * @mst: The master node
 * @expected: The expected hash of the master node
 *
 * This checks the hash of a master node against a given expected hash.
 * Note that we have two master nodes on a UBIFS image which have different
 * sequence numbers and consequently different CRCs. To be able to match
 * both master nodes we exclude the common node header containing the sequence
 * number and CRC from the hash.
 *
 * Returns 0 if the hashes are equal, a negative error code otherwise.
 */
static int mst_node_check_hash(const struct ubifs_info *c,
                               const struct ubifs_mst_node *mst,
                               const u8 *expected)
{
        u8 calc[UBIFS_MAX_HASH_LEN];
        const void *node = mst;
        int ret;

        ret = crypto_shash_tfm_digest(c->hash_tfm, node + sizeof(struct ubifs_ch),
                                UBIFS_MST_NODE_SZ - sizeof(struct ubifs_ch),
                                calc);
        if (ret)
                return ret;

        if (ubifs_check_hash(c, expected, calc))
                return -EPERM;

        return 0;
}

/**
 * scan_for_master - search the valid master node.
 * @c: UBIFS file-system description object
 *
 * This function scans the master node LEBs and search for the latest master
 * node. Returns zero in case of success, %-EUCLEAN if there master area is
 * corrupted and requires recovery, and a negative error code in case of
 * failure.
 */
static int scan_for_master(struct ubifs_info *c)
{
        struct ubifs_scan_leb *sleb;
        struct ubifs_scan_node *snod;
        int lnum, offs = 0, nodes_cnt, err;

        lnum = UBIFS_MST_LNUM;

        sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
        if (IS_ERR(sleb))
                return PTR_ERR(sleb);
        nodes_cnt = sleb->nodes_cnt;
        if (nodes_cnt > 0) {
                snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node,
                                  list);
                if (snod->type != UBIFS_MST_NODE)
                        goto out_dump;
                memcpy(c->mst_node, snod->node, snod->len);
                offs = snod->offs;
        }
        ubifs_scan_destroy(sleb);

        lnum += 1;

        sleb = ubifs_scan(c, lnum, 0, c->sbuf, 1);
        if (IS_ERR(sleb))
                return PTR_ERR(sleb);
        if (sleb->nodes_cnt != nodes_cnt)
                goto out;
        if (!sleb->nodes_cnt)
                goto out;
        snod = list_entry(sleb->nodes.prev, struct ubifs_scan_node, list);
        if (snod->type != UBIFS_MST_NODE)
                goto out_dump;
        if (snod->offs != offs)
                goto out;
        if (ubifs_compare_master_node(c, c->mst_node, snod->node))
                goto out;

        c->mst_offs = offs;
        ubifs_scan_destroy(sleb);

        if (!ubifs_authenticated(c))
                return 0;

        if (ubifs_hmac_zero(c, c->mst_node->hmac)) {
                err = mst_node_check_hash(c, c->mst_node,
                                          c->sup_node->hash_mst);
                if (err)
                        ubifs_err(c, "Failed to verify master node hash");
        } else {
                err = ubifs_node_verify_hmac(c, c->mst_node,
                                        sizeof(struct ubifs_mst_node),
                                        offsetof(struct ubifs_mst_node, hmac));
                if (err)
                        ubifs_err(c, "Failed to verify master node HMAC");
        }

        if (err)
                return -EPERM;

        return 0;

out:
        ubifs_scan_destroy(sleb);
        return -EUCLEAN;

out_dump:
        ubifs_err(c, "unexpected node type %d master LEB %d:%d",
                  snod->type, lnum, snod->offs);
        ubifs_scan_destroy(sleb);
        return -EINVAL;
}

/**
 * validate_master - validate master node.
 * @c: UBIFS file-system description object
 *
 * This function validates data which was read from master node. Returns zero
 * if the data is all right and %-EINVAL if not.
 */
static int validate_master(const struct ubifs_info *c)
{
        long long main_sz;
        int err;

        if (c->max_sqnum >= SQNUM_WATERMARK) {
                err = 1;
                goto out;
        }

        if (c->cmt_no >= c->max_sqnum) {
                err = 2;
                goto out;
        }

        if (c->highest_inum >= INUM_WATERMARK) {
                err = 3;
                goto out;
        }

        if (c->lhead_lnum < UBIFS_LOG_LNUM ||
            c->lhead_lnum >= UBIFS_LOG_LNUM + c->log_lebs ||
            c->lhead_offs < 0 || c->lhead_offs >= c->leb_size ||
            c->lhead_offs & (c->min_io_size - 1)) {
                err = 4;
                goto out;
        }

        if (c->zroot.lnum >= c->leb_cnt || c->zroot.lnum < c->main_first ||
            c->zroot.offs >= c->leb_size || c->zroot.offs & 7) {
                err = 5;
                goto out;
        }

        if (c->zroot.len < c->ranges[UBIFS_IDX_NODE].min_len ||
            c->zroot.len > c->ranges[UBIFS_IDX_NODE].max_len) {
                err = 6;
                goto out;
        }

        if (c->gc_lnum >= c->leb_cnt || c->gc_lnum < c->main_first) {
                err = 7;
                goto out;
        }

        if (c->ihead_lnum >= c->leb_cnt || c->ihead_lnum < c->main_first ||
            c->ihead_offs % c->min_io_size || c->ihead_offs < 0 ||
            c->ihead_offs > c->leb_size || c->ihead_offs & 7) {
                err = 8;
                goto out;
        }

        main_sz = (long long)c->main_lebs * c->leb_size;
        if (c->bi.old_idx_sz & 7 || c->bi.old_idx_sz >= main_sz) {
                err = 9;
                goto out;
        }

        if (c->lpt_lnum < c->lpt_first || c->lpt_lnum > c->lpt_last ||
            c->lpt_offs < 0 || c->lpt_offs + c->nnode_sz > c->leb_size) {
                err = 10;
                goto out;
        }

        if (c->nhead_lnum < c->lpt_first || c->nhead_lnum > c->lpt_last ||
            c->nhead_offs < 0 || c->nhead_offs % c->min_io_size ||
            c->nhead_offs > c->leb_size) {
                err = 11;
                goto out;
        }

        if (c->ltab_lnum < c->lpt_first || c->ltab_lnum > c->lpt_last ||
            c->ltab_offs < 0 ||
            c->ltab_offs + c->ltab_sz > c->leb_size) {
                err = 12;
                goto out;
        }

        if (c->big_lpt && (c->lsave_lnum < c->lpt_first ||
            c->lsave_lnum > c->lpt_last || c->lsave_offs < 0 ||
            c->lsave_offs + c->lsave_sz > c->leb_size)) {
                err = 13;
                goto out;
        }

        if (c->lscan_lnum < c->main_first || c->lscan_lnum >= c->leb_cnt) {
                err = 14;
                goto out;
        }

        if (c->lst.empty_lebs < 0 || c->lst.empty_lebs > c->main_lebs - 2) {
                err = 15;
                goto out;
        }

        if (c->lst.idx_lebs < 0 || c->lst.idx_lebs > c->main_lebs - 1) {
                err = 16;
                goto out;
        }

        if (c->lst.total_free < 0 || c->lst.total_free > main_sz ||
            c->lst.total_free & 7) {
                err = 17;
                goto out;
        }

        if (c->lst.total_dirty < 0 || (c->lst.total_dirty & 7)) {
                err = 18;
                goto out;
        }

        if (c->lst.total_used < 0 || (c->lst.total_used & 7)) {
                err = 19;
                goto out;
        }

        if (c->lst.total_free + c->lst.total_dirty +
            c->lst.total_used > main_sz) {
                err = 20;
                goto out;
        }

        if (c->lst.total_dead + c->lst.total_dark +
            c->lst.total_used + c->bi.old_idx_sz > main_sz) {
                err = 21;
                goto out;
        }

        if (c->lst.total_dead < 0 ||
            c->lst.total_dead > c->lst.total_free + c->lst.total_dirty ||
            c->lst.total_dead & 7) {
                err = 22;
                goto out;
        }

        if (c->lst.total_dark < 0 ||
            c->lst.total_dark > c->lst.total_free + c->lst.total_dirty ||
            c->lst.total_dark & 7) {
                err = 23;
                goto out;
        }

        return 0;

out:
        ubifs_err(c, "bad master node at offset %d error %d", c->mst_offs, err);
        ubifs_dump_node(c, c->mst_node, c->mst_node_alsz);
        return -EINVAL;
}

/**
 * ubifs_read_master - read master node.
 * @c: UBIFS file-system description object
 *
 * This function finds and reads the master node during file-system mount. If
 * the flash is empty, it creates default master node as well. Returns zero in
 * case of success and a negative error code in case of failure.
 */
int ubifs_read_master(struct ubifs_info *c)
{
        int err, old_leb_cnt;

        c->mst_node = kzalloc(c->mst_node_alsz, GFP_KERNEL);
        if (!c->mst_node)
                return -ENOMEM;

        err = scan_for_master(c);
        if (err) {
                if (err == -EUCLEAN)
                        err = ubifs_recover_master_node(c);
                if (err)
                        /*
                         * Note, we do not free 'c->mst_node' here because the
                         * unmount routine will take care of this.
                         */
                        return err;
        }

        /* Make sure that the recovery flag is clear */
        c->mst_node->flags &= cpu_to_le32(~UBIFS_MST_RCVRY);

        c->max_sqnum       = le64_to_cpu(c->mst_node->ch.sqnum);
        c->highest_inum    = le64_to_cpu(c->mst_node->highest_inum);
        c->cmt_no          = le64_to_cpu(c->mst_node->cmt_no);
        c->zroot.lnum      = le32_to_cpu(c->mst_node->root_lnum);
        c->zroot.offs      = le32_to_cpu(c->mst_node->root_offs);
        c->zroot.len       = le32_to_cpu(c->mst_node->root_len);
        c->lhead_lnum      = le32_to_cpu(c->mst_node->log_lnum);
        c->gc_lnum         = le32_to_cpu(c->mst_node->gc_lnum);
        c->ihead_lnum      = le32_to_cpu(c->mst_node->ihead_lnum);
        c->ihead_offs      = le32_to_cpu(c->mst_node->ihead_offs);
        c->bi.old_idx_sz   = le64_to_cpu(c->mst_node->index_size);
        c->lpt_lnum        = le32_to_cpu(c->mst_node->lpt_lnum);
        c->lpt_offs        = le32_to_cpu(c->mst_node->lpt_offs);
        c->nhead_lnum      = le32_to_cpu(c->mst_node->nhead_lnum);
        c->nhead_offs      = le32_to_cpu(c->mst_node->nhead_offs);
        c->ltab_lnum       = le32_to_cpu(c->mst_node->ltab_lnum);
        c->ltab_offs       = le32_to_cpu(c->mst_node->ltab_offs);
        c->lsave_lnum      = le32_to_cpu(c->mst_node->lsave_lnum);
        c->lsave_offs      = le32_to_cpu(c->mst_node->lsave_offs);
        c->lscan_lnum      = le32_to_cpu(c->mst_node->lscan_lnum);
        c->lst.empty_lebs  = le32_to_cpu(c->mst_node->empty_lebs);
        c->lst.idx_lebs    = le32_to_cpu(c->mst_node->idx_lebs);
        old_leb_cnt        = le32_to_cpu(c->mst_node->leb_cnt);
        c->lst.total_free  = le64_to_cpu(c->mst_node->total_free);
        c->lst.total_dirty = le64_to_cpu(c->mst_node->total_dirty);
        c->lst.total_used  = le64_to_cpu(c->mst_node->total_used);
        c->lst.total_dead  = le64_to_cpu(c->mst_node->total_dead);
        c->lst.total_dark  = le64_to_cpu(c->mst_node->total_dark);

        ubifs_copy_hash(c, c->mst_node->hash_root_idx, c->zroot.hash);

        c->calc_idx_sz = c->bi.old_idx_sz;

        if (c->mst_node->flags & cpu_to_le32(UBIFS_MST_NO_ORPHS))
                c->no_orphs = 1;

        if (old_leb_cnt != c->leb_cnt) {
                /* The file system has been resized */
                int growth = c->leb_cnt - old_leb_cnt;

                if (c->leb_cnt < old_leb_cnt ||
                    c->leb_cnt < UBIFS_MIN_LEB_CNT) {
                        ubifs_err(c, "bad leb_cnt on master node");
                        ubifs_dump_node(c, c->mst_node, c->mst_node_alsz);
                        return -EINVAL;
                }

                dbg_mnt("Auto resizing (master) from %d LEBs to %d LEBs",
                        old_leb_cnt, c->leb_cnt);
                c->lst.empty_lebs += growth;
                c->lst.total_free += growth * (long long)c->leb_size;
                c->lst.total_dark += growth * (long long)c->dark_wm;

                /*
                 * Reflect changes back onto the master node. N.B. the master
                 * node gets written immediately whenever mounting (or
                 * remounting) in read-write mode, so we do not need to write it
                 * here.
                 */
                c->mst_node->leb_cnt = cpu_to_le32(c->leb_cnt);
                c->mst_node->empty_lebs = cpu_to_le32(c->lst.empty_lebs);
                c->mst_node->total_free = cpu_to_le64(c->lst.total_free);
                c->mst_node->total_dark = cpu_to_le64(c->lst.total_dark);
        }

        err = validate_master(c);
        if (err)
                return err;

        err = dbg_old_index_check_init(c, &c->zroot);

        return err;
}

/**
 * ubifs_write_master - write master node.
 * @c: UBIFS file-system description object
 *
 * This function writes the master node. Returns zero in case of success and a
 * negative error code in case of failure. The master node is written twice to
 * enable recovery.
 */
int ubifs_write_master(struct ubifs_info *c)
{
        int err, lnum, offs, len;

        ubifs_assert(c, !c->ro_media && !c->ro_mount);
        if (c->ro_error)
                return -EROFS;

        lnum = UBIFS_MST_LNUM;
        offs = c->mst_offs + c->mst_node_alsz;
        len = UBIFS_MST_NODE_SZ;

        if (offs + UBIFS_MST_NODE_SZ > c->leb_size) {
                err = ubifs_leb_unmap(c, lnum);
                if (err)
                        return err;
                offs = 0;
        }

        c->mst_offs = offs;
        c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);

        ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);
        err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
                                    offsetof(struct ubifs_mst_node, hmac));
        if (err)
                return err;

        lnum += 1;

        if (offs == 0) {
                err = ubifs_leb_unmap(c, lnum);
                if (err)
                        return err;
        }
        err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
                                    offsetof(struct ubifs_mst_node, hmac));

        return err;
}