Commit message: qcow2: Validate active L1 table offset and size (CVE-2014-0144)

This avoids an unbounded allocation.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
CVE: CVE-2014-0144
CWE: CWE-20
Vulnerability description: QEMU before 2.0.0 block drivers for CLOOP, QCOW2 version 2 and various other image formats are vulnerable to potential memory corruptions, integer/buffer overflows or crash caused by missing input validations which could allow a remote user to execute arbitrary code on the host with the privileges of the QEMU process.

Project: qemu
File: qcow2.c

static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num,
                          int remaining_sectors, QEMUIOVector *qiov)
{
    BDRVQcowState *s = bs->opaque;
    int index_in_cluster, n1;
    int ret;
    int cur_nr_sectors; /* number of sectors in current iteration */
    uint64_t cluster_offset = 0;
    uint64_t bytes_done = 0;
    QEMUIOVector hd_qiov;
    uint8_t *cluster_data = NULL;

    qemu_iovec_init(&hd_qiov, qiov->niov);

    qemu_co_mutex_lock(&s->lock);

    while (remaining_sectors != 0) {

        /* prepare next request */
        cur_nr_sectors = remaining_sectors;
        if (s->crypt_method) {
            cur_nr_sectors = MIN(cur_nr_sectors,
                QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors);
        }

        ret = qcow2_get_cluster_offset(bs, sector_num << 9,
            &cur_nr_sectors, &cluster_offset);
        if (ret < 0) {
            goto fail;
        }

        index_in_cluster = sector_num & (s->cluster_sectors - 1);

        qemu_iovec_reset(&hd_qiov);
        qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
            cur_nr_sectors * 512);

        switch (ret) {
        case QCOW2_CLUSTER_UNALLOCATED:

            if (bs->backing_hd) {
                /* read from the base image */
                n1 = qcow2_backing_read1(bs->backing_hd, &hd_qiov,
                    sector_num, cur_nr_sectors);
                if (n1 > 0) {
                    BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO);
                    qemu_co_mutex_unlock(&s->lock);
                    ret = bdrv_co_readv(bs->backing_hd, sector_num,
                                        n1, &hd_qiov);
                    qemu_co_mutex_lock(&s->lock);
                    if (ret < 0) {
                        goto fail;
                    }
                }
            } else {
                /* Note: in this case, no need to wait */
                qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors);
            }
            break;

        case QCOW2_CLUSTER_ZERO:
            qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors);
            break;

        case QCOW2_CLUSTER_COMPRESSED:
            /* add AIO support for compressed blocks ? */
            ret = qcow2_decompress_cluster(bs, cluster_offset);
            if (ret < 0) {
                goto fail;
            }

            qemu_iovec_from_buf(&hd_qiov, 0,
                s->cluster_cache + index_in_cluster * 512,
                512 * cur_nr_sectors);
            break;

        case QCOW2_CLUSTER_NORMAL:
            if ((cluster_offset & 511) != 0) {
                ret = -EIO;
                goto fail;
            }

            if (s->crypt_method) {
                /*
                 * For encrypted images, read everything into a temporary
                 * contiguous buffer on which the AES functions can work.
                 */
                if (!cluster_data) {
                    cluster_data =
                        qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
                }

                assert(cur_nr_sectors <=
                    QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors);
                qemu_iovec_reset(&hd_qiov);
                qemu_iovec_add(&hd_qiov, cluster_data,
                    512 * cur_nr_sectors);
            }

            BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
            qemu_co_mutex_unlock(&s->lock);
            ret = bdrv_co_readv(bs->file,
                                (cluster_offset >> 9) + index_in_cluster,
                                cur_nr_sectors, &hd_qiov);
            qemu_co_mutex_lock(&s->lock);
            if (ret < 0) {
                goto fail;
            }
            if (s->crypt_method) {
                qcow2_encrypt_sectors(s, sector_num,  cluster_data,
                    cluster_data, cur_nr_sectors, 0, &s->aes_decrypt_key);
                qemu_iovec_from_buf(qiov, bytes_done,
                    cluster_data, 512 * cur_nr_sectors);
            }
            break;

        default:
            g_assert_not_reached();
            ret = -EIO;
            goto fail;
        }

        remaining_sectors -= cur_nr_sectors;
        sector_num += cur_nr_sectors;
        bytes_done += cur_nr_sectors * 512;
    }
    ret = 0;

fail:
    qemu_co_mutex_unlock(&s->lock);

    qemu_iovec_destroy(&hd_qiov);
    qemu_vfree(cluster_data);

    return ret;
}

Project: qemu
File: qcow2.c

static int preallocate(BlockDriverState *bs)
{
    uint64_t nb_sectors;
    uint64_t offset;
    uint64_t host_offset = 0;
    int num;
    int ret;
    QCowL2Meta *meta;

    nb_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
    offset = 0;

    while (nb_sectors) {
        num = MIN(nb_sectors, INT_MAX >> BDRV_SECTOR_BITS);
        ret = qcow2_alloc_cluster_offset(bs, offset, &num,
                                         &host_offset, &meta);
        if (ret < 0) {
            return ret;
        }

        if (meta != NULL) {
            ret = qcow2_alloc_cluster_link_l2(bs, meta);
            if (ret < 0) {
                qcow2_free_any_clusters(bs, meta->alloc_offset,
                                        meta->nb_clusters, QCOW2_DISCARD_NEVER);
                return ret;
            }

            /* There are no dependent requests, but we need to remove our
             * request from the list of in-flight requests */
            QLIST_REMOVE(meta, next_in_flight);
        }

        /* TODO Preallocate data if requested */

        nb_sectors -= num;
        offset += num << BDRV_SECTOR_BITS;
    }

    /*
     * It is expected that the image file is large enough to actually contain
     * all of the allocated clusters (otherwise we get failing reads after
     * EOF). Extend the image to the last allocated sector.
     */
    if (host_offset != 0) {
        uint8_t buf[BDRV_SECTOR_SIZE];
        memset(buf, 0, BDRV_SECTOR_SIZE);
        ret = bdrv_write(bs->file, (host_offset >> BDRV_SECTOR_BITS) + num - 1,
                         buf, 1);
        if (ret < 0) {
            return ret;
        }
    }

    return 0;
}

Project: qemu
File: qcow2.c

static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    int ret;

    qemu_co_mutex_lock(&s->lock);
    ret = qcow2_cache_flush(bs, s->l2_table_cache);
    if (ret < 0) {
        qemu_co_mutex_unlock(&s->lock);
        return ret;
    }

    if (qcow2_need_accurate_refcounts(s)) {
        ret = qcow2_cache_flush(bs, s->refcount_block_cache);
        if (ret < 0) {
            qemu_co_mutex_unlock(&s->lock);
            return ret;
        }
    }
    qemu_co_mutex_unlock(&s->lock);

    return 0;
}

Project: qemu
File: qcow2.c

int qcow2_mark_consistent(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;

    if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
        int ret = bdrv_flush(bs);
        if (ret < 0) {
            return ret;
        }

        s->incompatible_features &= ~QCOW2_INCOMPAT_CORRUPT;
        return qcow2_update_header(bs);
    }
    return 0;
}

Project: qemu
File: qcow2.c

static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result,
                       BdrvCheckMode fix)
{
    int ret = qcow2_check_refcounts(bs, result, fix);
    if (ret < 0) {
        return ret;
    }

    if (fix && result->check_errors == 0 && result->corruptions == 0) {
        ret = qcow2_mark_clean(bs);
        if (ret < 0) {
            return ret;
        }
        return qcow2_mark_consistent(bs);
    }
    return ret;
}

Project: qemu
File: qcow2.c

static int qcow2_amend_options(BlockDriverState *bs,
                               QEMUOptionParameter *options)
{
    BDRVQcowState *s = bs->opaque;
    int old_version = s->qcow_version, new_version = old_version;
    uint64_t new_size = 0;
    const char *backing_file = NULL, *backing_format = NULL;
    bool lazy_refcounts = s->use_lazy_refcounts;
    int ret;
    int i;

    for (i = 0; options[i].name; i++)
    {
        if (!options[i].assigned) {
            /* only change explicitly defined options */
            continue;
        }

        if (!strcmp(options[i].name, "compat")) {
            if (!options[i].value.s) {
                /* preserve default */
            } else if (!strcmp(options[i].value.s, "0.10")) {
                new_version = 2;
            } else if (!strcmp(options[i].value.s, "1.1")) {
                new_version = 3;
            } else {
                fprintf(stderr, "Unknown compatibility level %s.\n",
                        options[i].value.s);
                return -EINVAL;
            }
        } else if (!strcmp(options[i].name, "preallocation")) {
            fprintf(stderr, "Cannot change preallocation mode.\n");
            return -ENOTSUP;
        } else if (!strcmp(options[i].name, "size")) {
            new_size = options[i].value.n;
        } else if (!strcmp(options[i].name, "backing_file")) {
            backing_file = options[i].value.s;
        } else if (!strcmp(options[i].name, "backing_fmt")) {
            backing_format = options[i].value.s;
        } else if (!strcmp(options[i].name, "encryption")) {
            if ((options[i].value.n != !!s->crypt_method)) {
                fprintf(stderr, "Changing the encryption flag is not "
                        "supported.\n");
                return -ENOTSUP;
            }
        } else if (!strcmp(options[i].name, "cluster_size")) {
            if (options[i].value.n != s->cluster_size) {
                fprintf(stderr, "Changing the cluster size is not "
                        "supported.\n");
                return -ENOTSUP;
            }
        } else if (!strcmp(options[i].name, "lazy_refcounts")) {
            lazy_refcounts = options[i].value.n;
        } else {
            /* if this assertion fails, this probably means a new option was
             * added without having it covered here */
            assert(false);
        }
    }

    if (new_version != old_version) {
        if (new_version > old_version) {
            /* Upgrade */
            s->qcow_version = new_version;
            ret = qcow2_update_header(bs);
            if (ret < 0) {
                s->qcow_version = old_version;
                return ret;
            }
        } else {
            ret = qcow2_downgrade(bs, new_version);
            if (ret < 0) {
                return ret;
            }
        }
    }

    if (backing_file || backing_format) {
        ret = qcow2_change_backing_file(bs, backing_file ?: bs->backing_file,
                                        backing_format ?: bs->backing_format);
        if (ret < 0) {
            return ret;
        }
    }

    if (s->use_lazy_refcounts != lazy_refcounts) {
        if (lazy_refcounts) {
            if (s->qcow_version < 3) {
                fprintf(stderr, "Lazy refcounts only supported with compatibility "
                        "level 1.1 and above (use compat=1.1 or greater)\n");
                return -EINVAL;
            }
            s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
            ret = qcow2_update_header(bs);
            if (ret < 0) {
                s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
                return ret;
            }
            s->use_lazy_refcounts = true;
        } else {
            /* make image clean first */
            ret = qcow2_mark_clean(bs);
            if (ret < 0) {
                return ret;
            }
            /* now disallow lazy refcounts */
            s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
            ret = qcow2_update_header(bs);
            if (ret < 0) {
                s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
                return ret;
            }
            s->use_lazy_refcounts = false;
        }
    }

    if (new_size) {
        ret = bdrv_truncate(bs, new_size);
        if (ret < 0) {
            return ret;
        }
    }

    return 0;
}

Project: qemu
File: qcow2.c

static void bdrv_qcow2_init(void)
{
    bdrv_register(&bdrv_qcow2);
}

Project: qemu
File: qcow2.c

static int qcow2_change_backing_file(BlockDriverState *bs,
    const char *backing_file, const char *backing_fmt)
{
    pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
    pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");

    return qcow2_update_header(bs);
}

Project: qemu
File: qcow2.c

static coroutine_fn int qcow2_co_discard(BlockDriverState *bs,
    int64_t sector_num, int nb_sectors)
{
    int ret;
    BDRVQcowState *s = bs->opaque;

    qemu_co_mutex_lock(&s->lock);
    ret = qcow2_discard_clusters(bs, sector_num << BDRV_SECTOR_BITS,
        nb_sectors, QCOW2_DISCARD_REQUEST);
    qemu_co_mutex_unlock(&s->lock);
    return ret;
}

Project: qemu
File: qcow2.c

static coroutine_fn int qcow2_co_writev(BlockDriverState *bs,
                           int64_t sector_num,
                           int remaining_sectors,
                           QEMUIOVector *qiov)
{
    BDRVQcowState *s = bs->opaque;
    int index_in_cluster;
    int ret;
    int cur_nr_sectors; /* number of sectors in current iteration */
    uint64_t cluster_offset;
    QEMUIOVector hd_qiov;
    uint64_t bytes_done = 0;
    uint8_t *cluster_data = NULL;
    QCowL2Meta *l2meta = NULL;

    trace_qcow2_writev_start_req(qemu_coroutine_self(), sector_num,
                                 remaining_sectors);

    qemu_iovec_init(&hd_qiov, qiov->niov);

    s->cluster_cache_offset = -1; /* disable compressed cache */

    qemu_co_mutex_lock(&s->lock);

    while (remaining_sectors != 0) {

        l2meta = NULL;

        trace_qcow2_writev_start_part(qemu_coroutine_self());
        index_in_cluster = sector_num & (s->cluster_sectors - 1);
        cur_nr_sectors = remaining_sectors;
        if (s->crypt_method &&
            cur_nr_sectors >
            QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster) {
            cur_nr_sectors =
                QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors - index_in_cluster;
        }

        ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
            &cur_nr_sectors, &cluster_offset, &l2meta);
        if (ret < 0) {
            goto fail;
        }

        assert((cluster_offset & 511) == 0);

        qemu_iovec_reset(&hd_qiov);
        qemu_iovec_concat(&hd_qiov, qiov, bytes_done,
            cur_nr_sectors * 512);

        if (s->crypt_method) {
            if (!cluster_data) {
                cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS *
                                                 s->cluster_size);
            }

            assert(hd_qiov.size <=
                   QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size);
            qemu_iovec_to_buf(&hd_qiov, 0, cluster_data, hd_qiov.size);

            qcow2_encrypt_sectors(s, sector_num, cluster_data,
                cluster_data, cur_nr_sectors, 1, &s->aes_encrypt_key);

            qemu_iovec_reset(&hd_qiov);
            qemu_iovec_add(&hd_qiov, cluster_data,
                cur_nr_sectors * 512);
        }

        ret = qcow2_pre_write_overlap_check(bs, 0,
                cluster_offset + index_in_cluster * BDRV_SECTOR_SIZE,
                cur_nr_sectors * BDRV_SECTOR_SIZE);
        if (ret < 0) {
            goto fail;
        }

        qemu_co_mutex_unlock(&s->lock);
        BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
        trace_qcow2_writev_data(qemu_coroutine_self(),
                                (cluster_offset >> 9) + index_in_cluster);
        ret = bdrv_co_writev(bs->file,
                             (cluster_offset >> 9) + index_in_cluster,
                             cur_nr_sectors, &hd_qiov);
        qemu_co_mutex_lock(&s->lock);
        if (ret < 0) {
            goto fail;
        }

        while (l2meta != NULL) {
            QCowL2Meta *next;

            ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
            if (ret < 0) {
                goto fail;
            }

            /* Take the request off the list of running requests */
            if (l2meta->nb_clusters != 0) {
                QLIST_REMOVE(l2meta, next_in_flight);
            }

            qemu_co_queue_restart_all(&l2meta->dependent_requests);

            next = l2meta->next;
            g_free(l2meta);
            l2meta = next;
        }

        remaining_sectors -= cur_nr_sectors;
        sector_num += cur_nr_sectors;
        bytes_done += cur_nr_sectors * 512;
        trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_nr_sectors);
    }
    ret = 0;

fail:
    qemu_co_mutex_unlock(&s->lock);

    while (l2meta != NULL) {
        QCowL2Meta *next;

        if (l2meta->nb_clusters != 0) {
            QLIST_REMOVE(l2meta, next_in_flight);
        }
        qemu_co_queue_restart_all(&l2meta->dependent_requests);

        next = l2meta->next;
        g_free(l2meta);
        l2meta = next;
    }

    qemu_iovec_destroy(&hd_qiov);
    qemu_vfree(cluster_data);
    trace_qcow2_writev_done_req(qemu_coroutine_self(), ret);

    return ret;
}

Project: qemu
File: qcow2.c

static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
    BDRVQcowState *s = bs->opaque;
    bdi->unallocated_blocks_are_zero = true;
    bdi->can_write_zeroes_with_unmap = (s->qcow_version >= 3);
    bdi->cluster_size = s->cluster_size;
    bdi->vm_state_offset = qcow2_vm_state_offset(s);
    return 0;
}

Project: qemu
File: qcow2.c

int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
                  int64_t sector_num, int nb_sectors)
{
    int n1;
    if ((sector_num + nb_sectors) <= bs->total_sectors)
        return nb_sectors;
    if (sector_num >= bs->total_sectors)
        n1 = 0;
    else
        n1 = bs->total_sectors - sector_num;

    qemu_iovec_memset(qiov, 512 * n1, 0, 512 * (nb_sectors - n1));

    return n1;
}

Project: qemu
File: qcow2.c

static void qcow2_invalidate_cache(BlockDriverState *bs, Error **errp)
{
    BDRVQcowState *s = bs->opaque;
    int flags = s->flags;
    AES_KEY aes_encrypt_key;
    AES_KEY aes_decrypt_key;
    uint32_t crypt_method = 0;
    QDict *options;
    Error *local_err = NULL;
    int ret;

    /*
     * Backing files are read-only which makes all of their metadata immutable,
     * that means we don't have to worry about reopening them here.
     */

    if (s->crypt_method) {
        crypt_method = s->crypt_method;
        memcpy(&aes_encrypt_key, &s->aes_encrypt_key, sizeof(aes_encrypt_key));
        memcpy(&aes_decrypt_key, &s->aes_decrypt_key, sizeof(aes_decrypt_key));
    }

    qcow2_close(bs);

    bdrv_invalidate_cache(bs->file, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        return;
    }

    memset(s, 0, sizeof(BDRVQcowState));
    options = qdict_clone_shallow(bs->options);

    ret = qcow2_open(bs, options, flags, &local_err);
    if (local_err) {
        error_setg(errp, "Could not reopen qcow2 layer: %s",
                   error_get_pretty(local_err));
        error_free(local_err);
        return;
    } else if (ret < 0) {
        error_setg_errno(errp, -ret, "Could not reopen qcow2 layer");
        return;
    }

    QDECREF(options);

    if (crypt_method) {
        s->crypt_method = crypt_method;
        memcpy(&s->aes_encrypt_key, &aes_encrypt_key, sizeof(aes_encrypt_key));
        memcpy(&s->aes_decrypt_key, &aes_decrypt_key, sizeof(aes_decrypt_key));
    }
}

Project: qemu
File: qcow2.c

static ImageInfoSpecific *qcow2_get_specific_info(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    ImageInfoSpecific *spec_info = g_new(ImageInfoSpecific, 1);

    *spec_info = (ImageInfoSpecific){
        .kind  = IMAGE_INFO_SPECIFIC_KIND_QCOW2,
        {
            .qcow2 = g_new(ImageInfoSpecificQCow2, 1),
        },
    };
    if (s->qcow_version == 2) {
        *spec_info->qcow2 = (ImageInfoSpecificQCow2){
            .compat = g_strdup("0.10"),
        };
    } else if (s->qcow_version == 3) {
        *spec_info->qcow2 = (ImageInfoSpecificQCow2){
            .compat             = g_strdup("1.1"),
            .lazy_refcounts     = s->compatible_features &
                                  QCOW2_COMPAT_LAZY_REFCOUNTS,
            .has_lazy_refcounts = true,
        };
    }

    return spec_info;
}

Project: qemu
File: qcow2.c

static int qcow2_downgrade(BlockDriverState *bs, int target_version)
{
    BDRVQcowState *s = bs->opaque;
    int current_version = s->qcow_version;
    int ret;

    if (target_version == current_version) {
        return 0;
    } else if (target_version > current_version) {
        return -EINVAL;
    } else if (target_version != 2) {
        return -EINVAL;
    }

    if (s->refcount_order != 4) {
        /* we would have to convert the image to a refcount_order == 4 image
         * here; however, since qemu (at the time of writing this) does not
         * support anything different than 4 anyway, there is no point in doing
         * so right now; however, we should error out (if qemu supports this in
         * the future and this code has not been adapted) */
        error_report("qcow2_downgrade: Image refcount orders other than 4 are "
                     "currently not supported.");
        return -ENOTSUP;
    }

    /* clear incompatible features */
    if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
        ret = qcow2_mark_clean(bs);
        if (ret < 0) {
            return ret;
        }
    }

    /* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
     * the first place; if that happens nonetheless, returning -ENOTSUP is the
     * best thing to do anyway */

    if (s->incompatible_features) {
        return -ENOTSUP;
    }

    /* since we can ignore compatible features, we can set them to 0 as well */
    s->compatible_features = 0;
    /* if lazy refcounts have been used, they have already been fixed through
     * clearing the dirty flag */

    /* clearing autoclear features is trivial */
    s->autoclear_features = 0;

    ret = qcow2_expand_zero_clusters(bs);
    if (ret < 0) {
        return ret;
    }

    s->qcow_version = target_version;
    ret = qcow2_update_header(bs);
    if (ret < 0) {
        s->qcow_version = current_version;
        return ret;
    }
    return 0;
}

Project: qemu
File: qcow2.c

static void qcow2_close(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    g_free(s->l1_table);
    /* else pre-write overlap checks in cache_destroy may crash */
    s->l1_table = NULL;

    if (!(bs->open_flags & BDRV_O_INCOMING)) {
        qcow2_cache_flush(bs, s->l2_table_cache);
        qcow2_cache_flush(bs, s->refcount_block_cache);

        qcow2_mark_clean(bs);
    }

    qcow2_cache_destroy(bs, s->l2_table_cache);
    qcow2_cache_destroy(bs, s->refcount_block_cache);

    g_free(s->unknown_header_fields);
    cleanup_unknown_header_ext(bs);

    g_free(s->cluster_cache);
    qemu_vfree(s->cluster_data);
    qcow2_refcount_close(bs);
    qcow2_free_snapshots(bs);
}

Project: qemu
File: qcow2.c

static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs,
    int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
{
    int ret;
    BDRVQcowState *s = bs->opaque;

    /* Emulate misaligned zero writes */
    if (sector_num % s->cluster_sectors || nb_sectors % s->cluster_sectors) {
        return -ENOTSUP;
    }

    /* Whatever is left can use real zero clusters */
    qemu_co_mutex_lock(&s->lock);
    ret = qcow2_zero_clusters(bs, sector_num << BDRV_SECTOR_BITS,
        nb_sectors);
    qemu_co_mutex_unlock(&s->lock);

    return ret;
}

Project: qemu
File: qcow2.c

static void dump_refcounts(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    int64_t nb_clusters, k, k1, size;
    int refcount;

    size = bdrv_getlength(bs->file);
    nb_clusters = size_to_clusters(s, size);
    for(k = 0; k < nb_clusters;) {
        k1 = k;
        refcount = get_refcount(bs, k);
        k++;
        while (k < nb_clusters && get_refcount(bs, k) == refcount)
            k++;
        printf("%" PRId64 ": refcount=%d nb=%" PRId64 "\n", k, refcount,
               k - k1);
    }
}

Project: qemu
File: qcow2.c

int qcow2_mark_dirty(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t val;
    int ret;

    assert(s->qcow_version >= 3);

    if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
        return 0; /* already dirty */
    }

    val = cpu_to_be64(s->incompatible_features | QCOW2_INCOMPAT_DIRTY);
    ret = bdrv_pwrite(bs->file, offsetof(QCowHeader, incompatible_features),
                      &val, sizeof(val));
    if (ret < 0) {
        return ret;
    }
    ret = bdrv_flush(bs->file);
    if (ret < 0) {
        return ret;
    }

    /* Only treat image as dirty if the header was updated successfully */
    s->incompatible_features |= QCOW2_INCOMPAT_DIRTY;
    return 0;
}

Project: qemu
File: qcow2.c

static size_t header_ext_add(char *buf, uint32_t magic, const void *s,
    size_t len, size_t buflen)
{
    QCowExtension *ext_backing_fmt = (QCowExtension*) buf;
    size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7);

    if (buflen < ext_len) {
        return -ENOSPC;
    }

    *ext_backing_fmt = (QCowExtension) {
        .magic  = cpu_to_be32(magic),
        .len    = cpu_to_be32(len),
    };
    memcpy(buf + sizeof(QCowExtension), s, len);

    return ext_len;
}

Project: qemu
File: qcow2.c

static void cleanup_unknown_header_ext(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;
    Qcow2UnknownHeaderExtension *uext, *next;

    QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) {
        QLIST_REMOVE(uext, next);
        g_free(uext);
    }
}

Project: qemu
File: qcow2.c

static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
{
    BDRVQcowState *s = bs->opaque;
    int len, i, ret = 0;
    QCowHeader header;
    QemuOpts *opts;
    Error *local_err = NULL;
    uint64_t ext_end;
    uint64_t l1_vm_state_index;
    const char *opt_overlap_check;
    int overlap_check_template = 0;

    ret = bdrv_pread(bs->file, 0, &header, sizeof(header));
    if (ret < 0) {
        error_setg_errno(errp, -ret, "Could not read qcow2 header");
        goto fail;
    }
    be32_to_cpus(&header.magic);
    be32_to_cpus(&header.version);
    be64_to_cpus(&header.backing_file_offset);
    be32_to_cpus(&header.backing_file_size);
    be64_to_cpus(&header.size);
    be32_to_cpus(&header.cluster_bits);
    be32_to_cpus(&header.crypt_method);
    be64_to_cpus(&header.l1_table_offset);
    be32_to_cpus(&header.l1_size);
    be64_to_cpus(&header.refcount_table_offset);
    be32_to_cpus(&header.refcount_table_clusters);
    be64_to_cpus(&header.snapshots_offset);
    be32_to_cpus(&header.nb_snapshots);

    if (header.magic != QCOW_MAGIC) {
        error_setg(errp, "Image is not in qcow2 format");
        ret = -EINVAL;
        goto fail;
    }
    if (header.version < 2 || header.version > 3) {
        report_unsupported(bs, errp, "QCOW version %d", header.version);
        ret = -ENOTSUP;
        goto fail;
    }

    s->qcow_version = header.version;

    /* Initialise cluster size */
    if (header.cluster_bits < MIN_CLUSTER_BITS ||
        header.cluster_bits > MAX_CLUSTER_BITS) {
        error_setg(errp, "Unsupported cluster size: 2^%i", header.cluster_bits);
        ret = -EINVAL;
        goto fail;
    }

    s->cluster_bits = header.cluster_bits;
    s->cluster_size = 1 << s->cluster_bits;
    s->cluster_sectors = 1 << (s->cluster_bits - 9);

    /* Initialise version 3 header fields */
    if (header.version == 2) {
        header.incompatible_features    = 0;
        header.compatible_features      = 0;
        header.autoclear_features       = 0;
        header.refcount_order           = 4;
        header.header_length            = 72;
    } else {
        be64_to_cpus(&header.incompatible_features);
        be64_to_cpus(&header.compatible_features);
        be64_to_cpus(&header.autoclear_features);
        be32_to_cpus(&header.refcount_order);
        be32_to_cpus(&header.header_length);

        if (header.header_length < 104) {
            error_setg(errp, "qcow2 header too short");
            ret = -EINVAL;
            goto fail;
        }
    }

    if (header.header_length > s->cluster_size) {
        error_setg(errp, "qcow2 header exceeds cluster size");
        ret = -EINVAL;
        goto fail;
    }

    if (header.header_length > sizeof(header)) {
        s->unknown_header_fields_size = header.header_length - sizeof(header);
        s->unknown_header_fields = g_malloc(s->unknown_header_fields_size);
        ret = bdrv_pread(bs->file, sizeof(header), s->unknown_header_fields,
                         s->unknown_header_fields_size);
        if (ret < 0) {
            error_setg_errno(errp, -ret, "Could not read unknown qcow2 header "
                             "fields");
            goto fail;
        }
    }

    if (header.backing_file_offset > s->cluster_size) {
        error_setg(errp, "Invalid backing file offset");
        ret = -EINVAL;
        goto fail;
    }

    if (header.backing_file_offset) {
        ext_end = header.backing_file_offset;
    } else {
        ext_end = 1 << header.cluster_bits;
    }

    /* Handle feature bits */
    s->incompatible_features    = header.incompatible_features;
    s->compatible_features      = header.compatible_features;
    s->autoclear_features       = header.autoclear_features;

    if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) {
        void *feature_table = NULL;
        qcow2_read_extensions(bs, header.header_length, ext_end,
                              &feature_table, NULL);
        report_unsupported_feature(bs, errp, feature_table,
                                   s->incompatible_features &
                                   ~QCOW2_INCOMPAT_MASK);
        ret = -ENOTSUP;
        g_free(feature_table);
        goto fail;
    }

    if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
        /* Corrupt images may not be written to unless they are being repaired
         */
        if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
            error_setg(errp, "qcow2: Image is corrupt; cannot be opened "
                       "read/write");
            ret = -EACCES;
            goto fail;
        }
    }

    /* Check support for various header values */
    if (header.refcount_order != 4) {
        report_unsupported(bs, errp, "%d bit reference counts",
                           1 << header.refcount_order);
        ret = -ENOTSUP;
        goto fail;
    }
    s->refcount_order = header.refcount_order;

    if (header.crypt_method > QCOW_CRYPT_AES) {
        error_setg(errp, "Unsupported encryption method: %i",
                   header.crypt_method);
        ret = -EINVAL;
        goto fail;
    }
    s->crypt_method_header = header.crypt_method;
    if (s->crypt_method_header) {
        bs->encrypted = 1;
    }

    s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
    s->l2_size = 1 << s->l2_bits;
    bs->total_sectors = header.size / 512;
    s->csize_shift = (62 - (s->cluster_bits - 8));
    s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
    s->cluster_offset_mask = (1LL << s->csize_shift) - 1;

    s->refcount_table_offset = header.refcount_table_offset;
    s->refcount_table_size =
        header.refcount_table_clusters << (s->cluster_bits - 3);

    if (header.refcount_table_clusters > (0x800000 >> s->cluster_bits)) {
        /* 8 MB refcount table is enough for 2 PB images at 64k cluster size
         * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
        error_setg(errp, "Reference count table too large");
        ret = -EINVAL;
        goto fail;
    }

    ret = validate_table_offset(bs, s->refcount_table_offset,
                                s->refcount_table_size, sizeof(uint64_t));
    if (ret < 0) {
        error_setg(errp, "Invalid reference count table offset");
        goto fail;
    }

    /* Snapshot table offset/length */
    if (header.nb_snapshots > QCOW_MAX_SNAPSHOTS) {
        error_setg(errp, "Too many snapshots");
        ret = -EINVAL;
        goto fail;
    }

    ret = validate_table_offset(bs, header.snapshots_offset,
                                header.nb_snapshots,
                                sizeof(QCowSnapshotHeader));
    if (ret < 0) {
        error_setg(errp, "Invalid snapshot table offset");
        goto fail;
    }

    s->snapshots_offset = header.snapshots_offset;
    s->nb_snapshots = header.nb_snapshots;

    /* read the level 1 table */
    if (header.l1_size > 0x2000000) {
        /* 32 MB L1 table is enough for 2 PB images at 64k cluster size
         * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
        error_setg(errp, "Active L1 table too large");
        ret = -EFBIG;
        goto fail;
    }
    s->l1_size = header.l1_size;

    l1_vm_state_index = size_to_l1(s, header.size);
    if (l1_vm_state_index > INT_MAX) {
        error_setg(errp, "Image is too big");
        ret = -EFBIG;
        goto fail;
    }
    s->l1_vm_state_index = l1_vm_state_index;

    /* the L1 table must contain at least enough entries to put
       header.size bytes */
    if (s->l1_size < s->l1_vm_state_index) {
        error_setg(errp, "L1 table is too small");
        ret = -EINVAL;
        goto fail;
    }

    ret = validate_table_offset(bs, header.l1_table_offset,
                                header.l1_size, sizeof(uint64_t));
    if (ret < 0) {
        error_setg(errp, "Invalid L1 table offset");
        goto fail;
    }
    s->l1_table_offset = header.l1_table_offset;


    if (s->l1_size > 0) {
        s->l1_table = g_malloc0(
            align_offset(s->l1_size * sizeof(uint64_t), 512));
        ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table,
                         s->l1_size * sizeof(uint64_t));
        if (ret < 0) {
            error_setg_errno(errp, -ret, "Could not read L1 table");
            goto fail;
        }
        for(i = 0;i < s->l1_size; i++) {
            be64_to_cpus(&s->l1_table[i]);
        }
    }

    /* alloc L2 table/refcount block cache */
    s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE);
    s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE);

    s->cluster_cache = g_malloc(s->cluster_size);
    /* one more sector for decompressed data alignment */
    s->cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
                                  + 512);
    s->cluster_cache_offset = -1;
    s->flags = flags;

    ret = qcow2_refcount_init(bs);
    if (ret != 0) {
        error_setg_errno(errp, -ret, "Could not initialize refcount handling");
        goto fail;
    }

    QLIST_INIT(&s->cluster_allocs);
    QTAILQ_INIT(&s->discards);

    /* read qcow2 extensions */
    if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL,
        &local_err)) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto fail;
    }

    /* read the backing file name */
    if (header.backing_file_offset != 0) {
        len = header.backing_file_size;
        if (len > 1023) {
            len = 1023;
        }
        ret = bdrv_pread(bs->file, header.backing_file_offset,
                         bs->backing_file, len);
        if (ret < 0) {
            error_setg_errno(errp, -ret, "Could not read backing file name");
            goto fail;
        }
        bs->backing_file[len] = '\0';
    }

    ret = qcow2_read_snapshots(bs);
    if (ret < 0) {
        error_setg_errno(errp, -ret, "Could not read snapshots");
        goto fail;
    }

    /* Clear unknown autoclear feature bits */
    if (!bs->read_only && !(flags & BDRV_O_INCOMING) && s->autoclear_features) {
        s->autoclear_features = 0;
        ret = qcow2_update_header(bs);
        if (ret < 0) {
            error_setg_errno(errp, -ret, "Could not update qcow2 header");
            goto fail;
        }
    }

    /* Initialise locks */
    qemu_co_mutex_init(&s->lock);

    /* Repair image if dirty */
    if (!(flags & (BDRV_O_CHECK | BDRV_O_INCOMING)) && !bs->read_only &&
        (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) {
        BdrvCheckResult result = {0};

        ret = qcow2_check(bs, &result, BDRV_FIX_ERRORS);
        if (ret < 0) {
            error_setg_errno(errp, -ret, "Could not repair dirty image");
            goto fail;
        }
    }

    /* Enable lazy_refcounts according to image and command line options */
    opts = qemu_opts_create(&qcow2_runtime_opts, NULL, 0, &error_abort);
    qemu_opts_absorb_qdict(opts, options, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
        ret = -EINVAL;
        goto fail;
    }

    s->use_lazy_refcounts = qemu_opt_get_bool(opts, QCOW2_OPT_LAZY_REFCOUNTS,
        (s->compatible_features & QCOW2_COMPAT_LAZY_REFCOUNTS));

    s->discard_passthrough[QCOW2_DISCARD_NEVER] = false;
    s->discard_passthrough[QCOW2_DISCARD_ALWAYS] = true;
    s->discard_passthrough[QCOW2_DISCARD_REQUEST] =
        qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_REQUEST,
                          flags & BDRV_O_UNMAP);
    s->discard_passthrough[QCOW2_DISCARD_SNAPSHOT] =
        qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SNAPSHOT, true);
    s->discard_passthrough[QCOW2_DISCARD_OTHER] =
        qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_OTHER, false);

    opt_overlap_check = qemu_opt_get(opts, "overlap-check") ?: "cached";
    if (!strcmp(opt_overlap_check, "none")) {
        overlap_check_template = 0;
    } else if (!strcmp(opt_overlap_check, "constant")) {
        overlap_check_template = QCOW2_OL_CONSTANT;
    } else if (!strcmp(opt_overlap_check, "cached")) {
        overlap_check_template = QCOW2_OL_CACHED;
    } else if (!strcmp(opt_overlap_check, "all")) {
        overlap_check_template = QCOW2_OL_ALL;
    } else {
        error_setg(errp, "Unsupported value '%s' for qcow2 option "
                   "'overlap-check'. Allowed are either of the following: "
                   "none, constant, cached, all", opt_overlap_check);
        qemu_opts_del(opts);
        ret = -EINVAL;
        goto fail;
    }

    s->overlap_check = 0;
    for (i = 0; i < QCOW2_OL_MAX_BITNR; i++) {
        /* overlap-check defines a template bitmask, but every flag may be
         * overwritten through the associated boolean option */
        s->overlap_check |=
            qemu_opt_get_bool(opts, overlap_bool_option_names[i],
                              overlap_check_template & (1 << i)) << i;
    }

    qemu_opts_del(opts);

    if (s->use_lazy_refcounts && s->qcow_version < 3) {
        error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
                   "qemu 1.1 compatibility level");
        ret = -EINVAL;
        goto fail;
    }

#ifdef DEBUG_ALLOC
    {
        BdrvCheckResult result = {0};
        qcow2_check_refcounts(bs, &result, 0);
    }
#endif
    return ret;

 fail:
    g_free(s->unknown_header_fields);
    cleanup_unknown_header_ext(bs);
    qcow2_free_snapshots(bs);
    qcow2_refcount_close(bs);
    g_free(s->l1_table);
    /* else pre-write overlap checks in cache_destroy may crash */
    s->l1_table = NULL;
    if (s->l2_table_cache) {
        qcow2_cache_destroy(bs, s->l2_table_cache);
    }
    if (s->refcount_block_cache) {
        qcow2_cache_destroy(bs, s->refcount_block_cache);
    }
    g_free(s->cluster_cache);
    qemu_vfree(s->cluster_data);
    return ret;
}

Project: qemu
File: qcow2.c

static int qcow2_mark_clean(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;

    if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
        int ret = bdrv_flush(bs);
        if (ret < 0) {
            return ret;
        }

        s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY;
        return qcow2_update_header(bs);
    }
    return 0;
}

Project: qemu
File: qcow2.c

static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,
                              int64_t pos, int size)
{
    BDRVQcowState *s = bs->opaque;
    int growable = bs->growable;
    bool zero_beyond_eof = bs->zero_beyond_eof;
    int ret;

    BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD);
    bs->growable = 1;
    bs->zero_beyond_eof = false;
    ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size);
    bs->growable = growable;
    bs->zero_beyond_eof = zero_beyond_eof;

    return ret;
}

Project: qemu
File: qcow2.c

int qcow2_mark_corrupt(BlockDriverState *bs)
{
    BDRVQcowState *s = bs->opaque;

    s->incompatible_features |= QCOW2_INCOMPAT_CORRUPT;
    return qcow2_update_header(bs);
}

Project: qemu
File: qcow2.c

static int qcow2_create(const char *filename, QEMUOptionParameter *options,
                        Error **errp)
{
    const char *backing_file = NULL;
    const char *backing_fmt = NULL;
    uint64_t sectors = 0;
    int flags = 0;
    size_t cluster_size = DEFAULT_CLUSTER_SIZE;
    int prealloc = 0;
    int version = 3;
    Error *local_err = NULL;
    int ret;

    /* Read out options */
    while (options && options->name) {
        if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
            sectors = options->value.n / 512;
        } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) {
            backing_file = options->value.s;
        } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) {
            backing_fmt = options->value.s;
        } else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) {
            flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0;
        } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) {
            if (options->value.n) {
                cluster_size = options->value.n;
            }
        } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) {
            if (!options->value.s || !strcmp(options->value.s, "off")) {
                prealloc = 0;
            } else if (!strcmp(options->value.s, "metadata")) {
                prealloc = 1;
            } else {
                error_setg(errp, "Invalid preallocation mode: '%s'",
                           options->value.s);
                return -EINVAL;
            }
        } else if (!strcmp(options->name, BLOCK_OPT_COMPAT_LEVEL)) {
            if (!options->value.s) {
                /* keep the default */
            } else if (!strcmp(options->value.s, "0.10")) {
                version = 2;
            } else if (!strcmp(options->value.s, "1.1")) {
                version = 3;
            } else {
                error_setg(errp, "Invalid compatibility level: '%s'",
                           options->value.s);
                return -EINVAL;
            }
        } else if (!strcmp(options->name, BLOCK_OPT_LAZY_REFCOUNTS)) {
            flags |= options->value.n ? BLOCK_FLAG_LAZY_REFCOUNTS : 0;
        }
        options++;
    }

    if (backing_file && prealloc) {
        error_setg(errp, "Backing file and preallocation cannot be used at "
                   "the same time");
        return -EINVAL;
    }

    if (version < 3 && (flags & BLOCK_FLAG_LAZY_REFCOUNTS)) {
        error_setg(errp, "Lazy refcounts only supported with compatibility "
                   "level 1.1 and above (use compat=1.1 or greater)");
        return -EINVAL;
    }

    ret = qcow2_create2(filename, sectors, backing_file, backing_fmt, flags,
                        cluster_size, prealloc, options, version, &local_err);
    if (local_err) {
        error_propagate(errp, local_err);
    }
    return ret;
}

Project: qemu
File: qcow2.c

static int64_t coroutine_fn qcow2_co_get_block_status(BlockDriverState *bs,
        int64_t sector_num, int nb_sectors, int *pnum)
{
    BDRVQcowState *s = bs->opaque;
    uint64_t cluster_offset;
    int index_in_cluster, ret;
    int64_t status = 0;

    *pnum = nb_sectors;
    qemu_co_mutex_lock(&s->lock);
    ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset);
    qemu_co_mutex_unlock(&s->lock);
    if (ret < 0) {
        return ret;
    }

    if (cluster_offset != 0 && ret != QCOW2_CLUSTER_COMPRESSED &&
        !s->crypt_method) {
        index_in_cluster = sector_num & (s->cluster_sectors - 1);
        cluster_offset |= (index_in_cluster << BDRV_SECTOR_BITS);
        status |= BDRV_BLOCK_OFFSET_VALID | cluster_offset;
    }
    if (ret == QCOW2_CLUSTER_ZERO) {
        status |= BDRV_BLOCK_ZERO;
    } else if (ret != QCOW2_CLUSTER_UNALLOCATED) {
        status |= BDRV_BLOCK_DATA;
    }
    return status;
}