/*
 * Copyright (C) Qu Wenruo 2017.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License v2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program.
 */

/*
 * The module is used to catch unexpected/corrupted tree block data.
 * Such behavior can be caused either by a fuzzed image or bugs.
 *
 * The objective is to do leaf/node validation checks when tree block is read
 * from disk, and check *every* possible member, so other code won't
 * need to checking them again.
 *
 * Due to the potential and unwanted damage, every checker needs to be
 * carefully reviewed otherwise so it does not prevent mount of valid images.
 */

#include "ctree.h"
#include "tree-checker.h"
#include "disk-io.h"
#include "compression.h"

/*
 * Error message should follow the following format:
 * corrupt <type>: <identifier>, <reason>[, <bad_value>]
 *
 * @type:       leaf or node
 * @identifier: the necessary info to locate the leaf/node.
 *              It's recommened to decode key.objecitd/offset if it's
 *              meaningful.
 * @reason:     describe the error
 * @bad_value:  optional, it's recommened to output bad value and its
 *              expected value (range).
 *
 * Since comma is used to separate the components, only space is allowed
 * inside each component.
 */

/*
 * Append generic "corrupt leaf/node root=%llu block=%llu slot=%d: " to @fmt.
 * Allows callers to customize the output.
 */
__printf(4, 5)
static void generic_err(const struct btrfs_root *root,
                        const struct extent_buffer *eb, int slot,
                        const char *fmt, ...)
{
        struct va_format vaf;
        va_list args;

        va_start(args, fmt);

        vaf.fmt = fmt;
        vaf.va = &args;

        btrfs_crit(root->fs_info,
                "corrupt %s: root=%llu block=%llu slot=%d, %pV",
                btrfs_header_level(eb) == 0 ? "leaf" : "node",
                root->objectid, btrfs_header_bytenr(eb), slot, &vaf);
        va_end(args);
}

/*
 * Customized reporter for extent data item, since its key objectid and
 * offset has its own meaning.
 */
__printf(4, 5)
static void file_extent_err(const struct btrfs_root *root,
                            const struct extent_buffer *eb, int slot,
                            const char *fmt, ...)
{
        struct btrfs_key key;
        struct va_format vaf;
        va_list args;

        btrfs_item_key_to_cpu(eb, &key, slot);
        va_start(args, fmt);

        vaf.fmt = fmt;
        vaf.va = &args;

        btrfs_crit(root->fs_info,
        "corrupt %s: root=%llu block=%llu slot=%d ino=%llu file_offset=%llu, %pV",
                btrfs_header_level(eb) == 0 ? "leaf" : "node", root->objectid,
                btrfs_header_bytenr(eb), slot, key.objectid, key.offset, &vaf);
        va_end(args);
}

/*
 * Return 0 if the btrfs_file_extent_##name is aligned to @alignment
 * Else return 1
 */
#define CHECK_FE_ALIGNED(root, leaf, slot, fi, name, alignment)               \
({                                                                            \
        if (!IS_ALIGNED(btrfs_file_extent_##name((leaf), (fi)), (alignment))) \
                file_extent_err((root), (leaf), (slot),                       \
        "invalid %s for file extent, have %llu, should be aligned to %u",     \
                        (#name), btrfs_file_extent_##name((leaf), (fi)),      \
                        (alignment));                                         \
        (!IS_ALIGNED(btrfs_file_extent_##name((leaf), (fi)), (alignment)));   \
})

static int check_extent_data_item(struct btrfs_root *root,
                                  struct extent_buffer *leaf,
                                  struct btrfs_key *key, int slot)
{
        struct btrfs_file_extent_item *fi;
        u32 sectorsize = root->fs_info->sectorsize;
        u32 item_size = btrfs_item_size_nr(leaf, slot);

        if (!IS_ALIGNED(key->offset, sectorsize)) {
                file_extent_err(root, leaf, slot,
"unaligned file_offset for file extent, have %llu should be aligned to %u",
                        key->offset, sectorsize);
                return -EUCLEAN;
        }

        fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);

        if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
                file_extent_err(root, leaf, slot,
                "invalid type for file extent, have %u expect range [0, %u]",
                        btrfs_file_extent_type(leaf, fi),
                        BTRFS_FILE_EXTENT_TYPES);
                return -EUCLEAN;
        }

        /*
         * Support for new compression/encrption must introduce incompat flag,
         * and must be caught in open_ctree().
         */
        if (btrfs_file_extent_compression(leaf, fi) > BTRFS_COMPRESS_TYPES) {
                file_extent_err(root, leaf, slot,
        "invalid compression for file extent, have %u expect range [0, %u]",
                        btrfs_file_extent_compression(leaf, fi),
                        BTRFS_COMPRESS_TYPES);
                return -EUCLEAN;
        }
        if (btrfs_file_extent_encryption(leaf, fi)) {
                file_extent_err(root, leaf, slot,
                        "invalid encryption for file extent, have %u expect 0",
                        btrfs_file_extent_encryption(leaf, fi));
                return -EUCLEAN;
        }
        if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
                /* Inline extent must have 0 as key offset */
                if (key->offset) {
                        file_extent_err(root, leaf, slot,
                "invalid file_offset for inline file extent, have %llu expect 0",
                                key->offset);
                        return -EUCLEAN;
                }

                /* Compressed inline extent has no on-disk size, skip it */
                if (btrfs_file_extent_compression(leaf, fi) !=
                    BTRFS_COMPRESS_NONE)
                        return 0;

                /* Uncompressed inline extent size must match item size */
                if (item_size != BTRFS_FILE_EXTENT_INLINE_DATA_START +
                    btrfs_file_extent_ram_bytes(leaf, fi)) {
                        file_extent_err(root, leaf, slot,
        "invalid ram_bytes for uncompressed inline extent, have %u expect %llu",
                                item_size, BTRFS_FILE_EXTENT_INLINE_DATA_START +
                                btrfs_file_extent_ram_bytes(leaf, fi));
                        return -EUCLEAN;
                }
                return 0;
        }

        /* Regular or preallocated extent has fixed item size */
        if (item_size != sizeof(*fi)) {
                file_extent_err(root, leaf, slot,
        "invalid item size for reg/prealloc file extent, have %u expect %zu",
                        item_size, sizeof(*fi));
                return -EUCLEAN;
        }
        if (CHECK_FE_ALIGNED(root, leaf, slot, fi, ram_bytes, sectorsize) ||
            CHECK_FE_ALIGNED(root, leaf, slot, fi, disk_bytenr, sectorsize) ||
            CHECK_FE_ALIGNED(root, leaf, slot, fi, disk_num_bytes, sectorsize) ||
            CHECK_FE_ALIGNED(root, leaf, slot, fi, offset, sectorsize) ||
            CHECK_FE_ALIGNED(root, leaf, slot, fi, num_bytes, sectorsize))
                return -EUCLEAN;
        return 0;
}

static int check_csum_item(struct btrfs_root *root, struct extent_buffer *leaf,
                           struct btrfs_key *key, int slot)
{
        u32 sectorsize = root->fs_info->sectorsize;
        u32 csumsize = btrfs_super_csum_size(root->fs_info->super_copy);

        if (key->objectid != BTRFS_EXTENT_CSUM_OBJECTID) {
                generic_err(root, leaf, slot,
                "invalid key objectid for csum item, have %llu expect %llu",
                        key->objectid, BTRFS_EXTENT_CSUM_OBJECTID);
                return -EUCLEAN;
        }
        if (!IS_ALIGNED(key->offset, sectorsize)) {
                generic_err(root, leaf, slot,
        "unaligned key offset for csum item, have %llu should be aligned to %u",
                        key->offset, sectorsize);
                return -EUCLEAN;
        }
        if (!IS_ALIGNED(btrfs_item_size_nr(leaf, slot), csumsize)) {
                generic_err(root, leaf, slot,
        "unaligned item size for csum item, have %u should be aligned to %u",
                        btrfs_item_size_nr(leaf, slot), csumsize);
                return -EUCLEAN;
        }
        return 0;
}

/*
 * Common point to switch the item-specific validation.
 */
static int check_leaf_item(struct btrfs_root *root,
                           struct extent_buffer *leaf,
                           struct btrfs_key *key, int slot)
{
        int ret = 0;

        switch (key->type) {
        case BTRFS_EXTENT_DATA_KEY:
                ret = check_extent_data_item(root, leaf, key, slot);
                break;
        case BTRFS_EXTENT_CSUM_KEY:
                ret = check_csum_item(root, leaf, key, slot);
                break;
        }
        return ret;
}

static int check_leaf(struct btrfs_root *root, struct extent_buffer *leaf,
                      bool check_item_data)
{
        struct btrfs_fs_info *fs_info = root->fs_info;
        /* No valid key type is 0, so all key should be larger than this key */
        struct btrfs_key prev_key = {0, 0, 0};
        struct btrfs_key key;
        u32 nritems = btrfs_header_nritems(leaf);
        int slot;

        /*
         * Extent buffers from a relocation tree have a owner field that
         * corresponds to the subvolume tree they are based on. So just from an
         * extent buffer alone we can not find out what is the id of the
         * corresponding subvolume tree, so we can not figure out if the extent
         * buffer corresponds to the root of the relocation tree or not. So
         * skip this check for relocation trees.
         */
        if (nritems == 0 && !btrfs_header_flag(leaf, BTRFS_HEADER_FLAG_RELOC)) {
                struct btrfs_root *check_root;

                key.objectid = btrfs_header_owner(leaf);
                key.type = BTRFS_ROOT_ITEM_KEY;
                key.offset = (u64)-1;

                check_root = btrfs_get_fs_root(fs_info, &key, false);
                /*
                 * The only reason we also check NULL here is that during
                 * open_ctree() some roots has not yet been set up.
                 */
                if (!IS_ERR_OR_NULL(check_root)) {
                        struct extent_buffer *eb;

                        eb = btrfs_root_node(check_root);
                        /* if leaf is the root, then it's fine */
                        if (leaf != eb) {
                                generic_err(check_root, leaf, 0,
                "invalid nritems, have %u should not be 0 for non-root leaf",
                                        nritems);
                                free_extent_buffer(eb);
                                return -EUCLEAN;
                        }
                        free_extent_buffer(eb);
                }
                return 0;
        }

        if (nritems == 0)
                return 0;

        /*
         * Check the following things to make sure this is a good leaf, and
         * leaf users won't need to bother with similar sanity checks:
         *
         * 1) key ordering
         * 2) item offset and size
         *    No overlap, no hole, all inside the leaf.
         * 3) item content
         *    If possible, do comprehensive sanity check.
         *    NOTE: All checks must only rely on the item data itself.
         */
        for (slot = 0; slot < nritems; slot++) {
                u32 item_end_expected;
                int ret;

                btrfs_item_key_to_cpu(leaf, &key, slot);

                /* Make sure the keys are in the right order */
                if (btrfs_comp_cpu_keys(&prev_key, &key) >= 0) {
                        generic_err(root, leaf, slot,
        "bad key order, prev (%llu %u %llu) current (%llu %u %llu)",
                                prev_key.objectid, prev_key.type,
                                prev_key.offset, key.objectid, key.type,
                                key.offset);
                        return -EUCLEAN;
                }

                /*
                 * Make sure the offset and ends are right, remember that the
                 * item data starts at the end of the leaf and grows towards the
                 * front.
                 */
                if (slot == 0)
                        item_end_expected = BTRFS_LEAF_DATA_SIZE(fs_info);
                else
                        item_end_expected = btrfs_item_offset_nr(leaf,
                                                                 slot - 1);
                if (btrfs_item_end_nr(leaf, slot) != item_end_expected) {
                        generic_err(root, leaf, slot,
                                "unexpected item end, have %u expect %u",
                                btrfs_item_end_nr(leaf, slot),
                                item_end_expected);
                        return -EUCLEAN;
                }

                /*
                 * Check to make sure that we don't point outside of the leaf,
                 * just in case all the items are consistent to each other, but
                 * all point outside of the leaf.
                 */
                if (btrfs_item_end_nr(leaf, slot) >
                    BTRFS_LEAF_DATA_SIZE(fs_info)) {
                        generic_err(root, leaf, slot,
                        "slot end outside of leaf, have %u expect range [0, %u]",
                                btrfs_item_end_nr(leaf, slot),
                                BTRFS_LEAF_DATA_SIZE(fs_info));
                        return -EUCLEAN;
                }

                /* Also check if the item pointer overlaps with btrfs item. */
                if (btrfs_item_nr_offset(slot) + sizeof(struct btrfs_item) >
                    btrfs_item_ptr_offset(leaf, slot)) {
                        generic_err(root, leaf, slot,
                "slot overlaps with its data, item end %lu data start %lu",
                                btrfs_item_nr_offset(slot) +
                                sizeof(struct btrfs_item),
                                btrfs_item_ptr_offset(leaf, slot));
                        return -EUCLEAN;
                }

                if (check_item_data) {
                        /*
                         * Check if the item size and content meet other
                         * criteria
                         */
                        ret = check_leaf_item(root, leaf, &key, slot);
                        if (ret < 0)
                                return ret;
                }

                prev_key.objectid = key.objectid;
                prev_key.type = key.type;
                prev_key.offset = key.offset;
        }

        return 0;
}

int btrfs_check_leaf_full(struct btrfs_root *root, struct extent_buffer *leaf)
{
        return check_leaf(root, leaf, true);
}

int btrfs_check_leaf_relaxed(struct btrfs_root *root,
                             struct extent_buffer *leaf)
{
        return check_leaf(root, leaf, false);
}

int btrfs_check_node(struct btrfs_root *root, struct extent_buffer *node)
{
        unsigned long nr = btrfs_header_nritems(node);
        struct btrfs_key key, next_key;
        int slot;
        u64 bytenr;
        int ret = 0;

        if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(root->fs_info)) {
                btrfs_crit(root->fs_info,
"corrupt node: root=%llu block=%llu, nritems too %s, have %lu expect range [1,%u]",
                           root->objectid, node->start,
                           nr == 0 ? "small" : "large", nr,
                           BTRFS_NODEPTRS_PER_BLOCK(root->fs_info));
                return -EUCLEAN;
        }

        for (slot = 0; slot < nr - 1; slot++) {
                bytenr = btrfs_node_blockptr(node, slot);
                btrfs_node_key_to_cpu(node, &key, slot);
                btrfs_node_key_to_cpu(node, &next_key, slot + 1);

                if (!bytenr) {
                        generic_err(root, node, slot,
                                "invalid NULL node pointer");
                        ret = -EUCLEAN;
                        goto out;
                }
                if (!IS_ALIGNED(bytenr, root->fs_info->sectorsize)) {
                        generic_err(root, node, slot,
                        "unaligned pointer, have %llu should be aligned to %u",
                                bytenr, root->fs_info->sectorsize);
                        ret = -EUCLEAN;
                        goto out;
                }

                if (btrfs_comp_cpu_keys(&key, &next_key) >= 0) {
                        generic_err(root, node, slot,
        "bad key order, current (%llu %u %llu) next (%llu %u %llu)",
                                key.objectid, key.type, key.offset,
                                next_key.objectid, next_key.type,
                                next_key.offset);
                        ret = -EUCLEAN;
                        goto out;
                }
        }
out:
        return ret;
}