diff options
Diffstat (limited to 'block-qcow.c')
| -rw-r--r-- | block-qcow.c | 677 |
1 files changed, 677 insertions, 0 deletions
diff --git a/block-qcow.c b/block-qcow.c new file mode 100644 index 0000000..ed6359f --- /dev/null +++ b/block-qcow.c @@ -0,0 +1,677 @@ +/* + * Block driver for the QCOW format + * + * Copyright (c) 2004 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#include "vl.h" +#include "block_int.h" +#include "zlib.h" +#include "aes.h" + +/**************************************************************/ +/* QEMU COW block driver with compression and encryption support */ + +#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb) +#define QCOW_VERSION 1 + +#define QCOW_CRYPT_NONE 0 +#define QCOW_CRYPT_AES 1 + +#define QCOW_OFLAG_COMPRESSED (1LL << 63) + +typedef struct QCowHeader { + uint32_t magic; + uint32_t version; + uint64_t backing_file_offset; + uint32_t backing_file_size; + uint32_t mtime; + uint64_t size; /* in bytes */ + uint8_t cluster_bits; + uint8_t l2_bits; + uint32_t crypt_method; + uint64_t l1_table_offset; +} QCowHeader; + +#define L2_CACHE_SIZE 16 + +typedef struct BDRVQcowState { + int fd; + int cluster_bits; + int cluster_size; + int cluster_sectors; + int l2_bits; + int l2_size; + int l1_size; + uint64_t cluster_offset_mask; + uint64_t l1_table_offset; + uint64_t *l1_table; + uint64_t *l2_cache; + uint64_t l2_cache_offsets[L2_CACHE_SIZE]; + uint32_t l2_cache_counts[L2_CACHE_SIZE]; + uint8_t *cluster_cache; + uint8_t *cluster_data; + uint64_t cluster_cache_offset; + uint32_t crypt_method; /* current crypt method, 0 if no key yet */ + uint32_t crypt_method_header; + AES_KEY aes_encrypt_key; + AES_KEY aes_decrypt_key; +} BDRVQcowState; + +static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset); + +static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename) +{ + const QCowHeader *cow_header = (const void *)buf; + + if (be32_to_cpu(cow_header->magic) == QCOW_MAGIC && + be32_to_cpu(cow_header->version) == QCOW_VERSION) + return 100; + else + return 0; +} + +static int qcow_open(BlockDriverState *bs, const char *filename) +{ + BDRVQcowState *s = bs->opaque; + int fd, len, i, shift; + QCowHeader header; + + fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE); + if (fd < 0) { + fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE); + if (fd < 0) + return -1; + } + s->fd = fd; + if (read(fd, &header, sizeof(header)) != sizeof(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); + be32_to_cpus(&header.mtime); + be64_to_cpus(&header.size); + be32_to_cpus(&header.crypt_method); + be64_to_cpus(&header.l1_table_offset); + + if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION) + goto fail; + if (header.size <= 1 || header.cluster_bits < 9) + goto fail; + if (header.crypt_method > QCOW_CRYPT_AES) + goto fail; + s->crypt_method_header = header.crypt_method; + if (s->crypt_method_header) + bs->encrypted = 1; + s->cluster_bits = header.cluster_bits; + s->cluster_size = 1 << s->cluster_bits; + s->cluster_sectors = 1 << (s->cluster_bits - 9); + s->l2_bits = header.l2_bits; + s->l2_size = 1 << s->l2_bits; + bs->total_sectors = header.size / 512; + s->cluster_offset_mask = (1LL << (63 - s->cluster_bits)) - 1; + + /* read the level 1 table */ + shift = s->cluster_bits + s->l2_bits; + s->l1_size = (header.size + (1LL << shift) - 1) >> shift; + + s->l1_table_offset = header.l1_table_offset; + s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t)); + if (!s->l1_table) + goto fail; + lseek64(fd, s->l1_table_offset, SEEK_SET); + if (read(fd, s->l1_table, s->l1_size * sizeof(uint64_t)) != + s->l1_size * sizeof(uint64_t)) + goto fail; + for(i = 0;i < s->l1_size; i++) { + be64_to_cpus(&s->l1_table[i]); + } + /* alloc L2 cache */ + s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t)); + if (!s->l2_cache) + goto fail; + s->cluster_cache = qemu_malloc(s->cluster_size); + if (!s->cluster_cache) + goto fail; + s->cluster_data = qemu_malloc(s->cluster_size); + if (!s->cluster_data) + goto fail; + s->cluster_cache_offset = -1; + + /* read the backing file name */ + if (header.backing_file_offset != 0) { + len = header.backing_file_size; + if (len > 1023) + len = 1023; + lseek64(fd, header.backing_file_offset, SEEK_SET); + if (read(fd, bs->backing_file, len) != len) + goto fail; + bs->backing_file[len] = '\0'; + } + return 0; + + fail: + qemu_free(s->l1_table); + qemu_free(s->l2_cache); + qemu_free(s->cluster_cache); + qemu_free(s->cluster_data); + close(fd); + return -1; +} + +static int qcow_set_key(BlockDriverState *bs, const char *key) +{ + BDRVQcowState *s = bs->opaque; + uint8_t keybuf[16]; + int len, i; + + memset(keybuf, 0, 16); + len = strlen(key); + if (len > 16) + len = 16; + /* XXX: we could compress the chars to 7 bits to increase + entropy */ + for(i = 0;i < len;i++) { + keybuf[i] = key[i]; + } + s->crypt_method = s->crypt_method_header; + + if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0) + return -1; + if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0) + return -1; +#if 0 + /* test */ + { + uint8_t in[16]; + uint8_t out[16]; + uint8_t tmp[16]; + for(i=0;i<16;i++) + in[i] = i; + AES_encrypt(in, tmp, &s->aes_encrypt_key); + AES_decrypt(tmp, out, &s->aes_decrypt_key); + for(i = 0; i < 16; i++) + printf(" %02x", tmp[i]); + printf("\n"); + for(i = 0; i < 16; i++) + printf(" %02x", out[i]); + printf("\n"); + } +#endif + return 0; +} + +/* The crypt function is compatible with the linux cryptoloop + algorithm for < 4 GB images. NOTE: out_buf == in_buf is + supported */ +static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num, + uint8_t *out_buf, const uint8_t *in_buf, + int nb_sectors, int enc, + const AES_KEY *key) +{ + union { + uint64_t ll[2]; + uint8_t b[16]; + } ivec; + int i; + + for(i = 0; i < nb_sectors; i++) { + ivec.ll[0] = cpu_to_le64(sector_num); + ivec.ll[1] = 0; + AES_cbc_encrypt(in_buf, out_buf, 512, key, + ivec.b, enc); + sector_num++; + in_buf += 512; + out_buf += 512; + } +} + +/* 'allocate' is: + * + * 0 to not allocate. + * + * 1 to allocate a normal cluster (for sector indexes 'n_start' to + * 'n_end') + * + * 2 to allocate a compressed cluster of size + * 'compressed_size'. 'compressed_size' must be > 0 and < + * cluster_size + * + * return 0 if not allocated. + */ +static uint64_t get_cluster_offset(BlockDriverState *bs, + uint64_t offset, int allocate, + int compressed_size, + int n_start, int n_end) +{ + BDRVQcowState *s = bs->opaque; + int min_index, i, j, l1_index, l2_index; + uint64_t l2_offset, *l2_table, cluster_offset, tmp; + uint32_t min_count; + int new_l2_table; + + l1_index = offset >> (s->l2_bits + s->cluster_bits); + l2_offset = s->l1_table[l1_index]; + new_l2_table = 0; + if (!l2_offset) { + if (!allocate) + return 0; + /* allocate a new l2 entry */ + l2_offset = lseek64(s->fd, 0, SEEK_END); + /* round to cluster size */ + l2_offset = (l2_offset + s->cluster_size - 1) & ~(s->cluster_size - 1); + /* update the L1 entry */ + s->l1_table[l1_index] = l2_offset; + tmp = cpu_to_be64(l2_offset); + lseek64(s->fd, s->l1_table_offset + l1_index * sizeof(tmp), SEEK_SET); + if (write(s->fd, &tmp, sizeof(tmp)) != sizeof(tmp)) + return 0; + new_l2_table = 1; + } + for(i = 0; i < L2_CACHE_SIZE; i++) { + if (l2_offset == s->l2_cache_offsets[i]) { + /* increment the hit count */ + if (++s->l2_cache_counts[i] == 0xffffffff) { + for(j = 0; j < L2_CACHE_SIZE; j++) { + s->l2_cache_counts[j] >>= 1; + } + } + l2_table = s->l2_cache + (i << s->l2_bits); + goto found; + } + } + /* not found: load a new entry in the least used one */ + min_index = 0; + min_count = 0xffffffff; + for(i = 0; i < L2_CACHE_SIZE; i++) { + if (s->l2_cache_counts[i] < min_count) { + min_count = s->l2_cache_counts[i]; + min_index = i; + } + } + l2_table = s->l2_cache + (min_index << s->l2_bits); + lseek(s->fd, l2_offset, SEEK_SET); + if (new_l2_table) { + memset(l2_table, 0, s->l2_size * sizeof(uint64_t)); + if (write(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) != + s->l2_size * sizeof(uint64_t)) + return 0; + } else { + if (read(s->fd, l2_table, s->l2_size * sizeof(uint64_t)) != + s->l2_size * sizeof(uint64_t)) + return 0; + } + s->l2_cache_offsets[min_index] = l2_offset; + s->l2_cache_counts[min_index] = 1; + found: + l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); + cluster_offset = be64_to_cpu(l2_table[l2_index]); + if (!cluster_offset || + ((cluster_offset & QCOW_OFLAG_COMPRESSED) && allocate == 1)) { + if (!allocate) + return 0; + /* allocate a new cluster */ + if ((cluster_offset & QCOW_OFLAG_COMPRESSED) && + (n_end - n_start) < s->cluster_sectors) { + /* if the cluster is already compressed, we must + decompress it in the case it is not completely + overwritten */ + if (decompress_cluster(s, cluster_offset) < 0) + return 0; + cluster_offset = lseek64(s->fd, 0, SEEK_END); + cluster_offset = (cluster_offset + s->cluster_size - 1) & + ~(s->cluster_size - 1); + /* write the cluster content */ + lseek64(s->fd, cluster_offset, SEEK_SET); + if (write(s->fd, s->cluster_cache, s->cluster_size) != + s->cluster_size) + return -1; + } else { + cluster_offset = lseek64(s->fd, 0, SEEK_END); + if (allocate == 1) { + /* round to cluster size */ + cluster_offset = (cluster_offset + s->cluster_size - 1) & + ~(s->cluster_size - 1); + ftruncate(s->fd, cluster_offset + s->cluster_size); + /* if encrypted, we must initialize the cluster + content which won't be written */ + if (s->crypt_method && + (n_end - n_start) < s->cluster_sectors) { + uint64_t start_sect; + start_sect = (offset & ~(s->cluster_size - 1)) >> 9; + memset(s->cluster_data + 512, 0xaa, 512); + for(i = 0; i < s->cluster_sectors; i++) { + if (i < n_start || i >= n_end) { + encrypt_sectors(s, start_sect + i, + s->cluster_data, + s->cluster_data + 512, 1, 1, + &s->aes_encrypt_key); + lseek64(s->fd, cluster_offset + i * 512, SEEK_SET); + if (write(s->fd, s->cluster_data, 512) != 512) + return -1; + } + } + } + } else { + cluster_offset |= QCOW_OFLAG_COMPRESSED | + (uint64_t)compressed_size << (63 - s->cluster_bits); + } + } + /* update L2 table */ + tmp = cpu_to_be64(cluster_offset); + l2_table[l2_index] = tmp; + lseek64(s->fd, l2_offset + l2_index * sizeof(tmp), SEEK_SET); + if (write(s->fd, &tmp, sizeof(tmp)) != sizeof(tmp)) + return 0; + } + return cluster_offset; +} + +static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num, + int nb_sectors, int *pnum) +{ + BDRVQcowState *s = bs->opaque; + int index_in_cluster, n; + uint64_t cluster_offset; + + cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0); + index_in_cluster = sector_num & (s->cluster_sectors - 1); + n = s->cluster_sectors - index_in_cluster; + if (n > nb_sectors) + n = nb_sectors; + *pnum = n; + return (cluster_offset != 0); +} + +static int decompress_buffer(uint8_t *out_buf, int out_buf_size, + const uint8_t *buf, int buf_size) +{ + z_stream strm1, *strm = &strm1; + int ret, out_len; + + memset(strm, 0, sizeof(*strm)); + + strm->next_in = (uint8_t *)buf; + strm->avail_in = buf_size; + strm->next_out = out_buf; + strm->avail_out = out_buf_size; + + ret = inflateInit2(strm, -12); + if (ret != Z_OK) + return -1; + ret = inflate(strm, Z_FINISH); + out_len = strm->next_out - out_buf; + if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) || + out_len != out_buf_size) { + inflateEnd(strm); + return -1; + } + inflateEnd(strm); + return 0; +} + +static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset) +{ + int ret, csize; + uint64_t coffset; + + coffset = cluster_offset & s->cluster_offset_mask; + if (s->cluster_cache_offset != coffset) { + csize = cluster_offset >> (63 - s->cluster_bits); + csize &= (s->cluster_size - 1); + lseek64(s->fd, coffset, SEEK_SET); + ret = read(s->fd, s->cluster_data, csize); + if (ret != csize) + return -1; + if (decompress_buffer(s->cluster_cache, s->cluster_size, + s->cluster_data, csize) < 0) { + return -1; + } + s->cluster_cache_offset = coffset; + } + return 0; +} + +static int qcow_read(BlockDriverState *bs, int64_t sector_num, + uint8_t *buf, int nb_sectors) +{ + BDRVQcowState *s = bs->opaque; + int ret, index_in_cluster, n; + uint64_t cluster_offset; + + while (nb_sectors > 0) { + cluster_offset = get_cluster_offset(bs, sector_num << 9, 0, 0, 0, 0); + index_in_cluster = sector_num & (s->cluster_sectors - 1); + n = s->cluster_sectors - index_in_cluster; + if (n > nb_sectors) + n = nb_sectors; + if (!cluster_offset) { + memset(buf, 0, 512 * n); + } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) { + if (decompress_cluster(s, cluster_offset) < 0) + return -1; + memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n); + } else { + lseek64(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET); + ret = read(s->fd, buf, n * 512); + if (ret != n * 512) + return -1; + if (s->crypt_method) { + encrypt_sectors(s, sector_num, buf, buf, n, 0, + &s->aes_decrypt_key); + } + } + nb_sectors -= n; + sector_num += n; + buf += n * 512; + } + return 0; +} + +static int qcow_write(BlockDriverState *bs, int64_t sector_num, + const uint8_t *buf, int nb_sectors) +{ + BDRVQcowState *s = bs->opaque; + int ret, index_in_cluster, n; + uint64_t cluster_offset; + + while (nb_sectors > 0) { + index_in_cluster = sector_num & (s->cluster_sectors - 1); + n = s->cluster_sectors - index_in_cluster; + if (n > nb_sectors) + n = nb_sectors; + cluster_offset = get_cluster_offset(bs, sector_num << 9, 1, 0, + index_in_cluster, + index_in_cluster + n); + if (!cluster_offset) + return -1; + lseek64(s->fd, cluster_offset + index_in_cluster * 512, SEEK_SET); + if (s->crypt_method) { + encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1, + &s->aes_encrypt_key); + ret = write(s->fd, s->cluster_data, n * 512); + } else { + ret = write(s->fd, buf, n * 512); + } + if (ret != n * 512) + return -1; + nb_sectors -= n; + sector_num += n; + buf += n * 512; + } + s->cluster_cache_offset = -1; /* disable compressed cache */ + return 0; +} + +static int qcow_close(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + qemu_free(s->l1_table); + qemu_free(s->l2_cache); + qemu_free(s->cluster_cache); + qemu_free(s->cluster_data); + close(s->fd); +} + +static int qcow_create(const char *filename, int64_t total_size, + const char *backing_file, int flags) +{ + int fd, header_size, backing_filename_len, l1_size, i, shift; + QCowHeader header; + char backing_filename[1024]; + uint64_t tmp; + struct stat st; + + fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE, + 0644); + if (fd < 0) + return -1; + memset(&header, 0, sizeof(header)); + header.magic = cpu_to_be32(QCOW_MAGIC); + header.version = cpu_to_be32(QCOW_VERSION); + header.size = cpu_to_be64(total_size * 512); + header_size = sizeof(header); + backing_filename_len = 0; + if (backing_file) { + realpath(backing_file, backing_filename); + if (stat(backing_filename, &st) != 0) { + return -1; + } + header.mtime = cpu_to_be32(st.st_mtime); + header.backing_file_offset = cpu_to_be64(header_size); + backing_filename_len = strlen(backing_filename); + header.backing_file_size = cpu_to_be32(backing_filename_len); + header_size += backing_filename_len; + header.cluster_bits = 9; /* 512 byte cluster to avoid copying + unmodifyed sectors */ + header.l2_bits = 12; /* 32 KB L2 tables */ + } else { + header.cluster_bits = 12; /* 4 KB clusters */ + header.l2_bits = 9; /* 4 KB L2 tables */ + } + header_size = (header_size + 7) & ~7; + shift = header.cluster_bits + header.l2_bits; + l1_size = ((total_size * 512) + (1LL << shift) - 1) >> shift; + + header.l1_table_offset = cpu_to_be64(header_size); + if (flags) { + header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES); + } else { + header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); + } + + /* write all the data */ + write(fd, &header, sizeof(header)); + if (backing_file) { + write(fd, backing_filename, backing_filename_len); + } + lseek(fd, header_size, SEEK_SET); + tmp = 0; + for(i = 0;i < l1_size; i++) { + write(fd, &tmp, sizeof(tmp)); + } + close(fd); + return 0; +} + +int qcow_get_cluster_size(BlockDriverState *bs) +{ + BDRVQcowState *s = bs->opaque; + if (bs->drv != &bdrv_qcow) + return -1; + return s->cluster_size; +} + +/* XXX: put compressed sectors first, then all the cluster aligned + tables to avoid losing bytes in alignment */ +int qcow_compress_cluster(BlockDriverState *bs, int64_t sector_num, + const uint8_t *buf) +{ + BDRVQcowState *s = bs->opaque; + z_stream strm; + int ret, out_len; + uint8_t *out_buf; + uint64_t cluster_offset; + + if (bs->drv != &bdrv_qcow) + return -1; + + out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); + if (!out_buf) + return -1; + + /* best compression, small window, no zlib header */ + memset(&strm, 0, sizeof(strm)); + ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, + Z_DEFLATED, -12, + 9, Z_DEFAULT_STRATEGY); + if (ret != 0) { + qemu_free(out_buf); + return -1; + } + + strm.avail_in = s->cluster_size; + strm.next_in = (uint8_t *)buf; + strm.avail_out = s->cluster_size; + strm.next_out = out_buf; + + ret = deflate(&strm, Z_FINISH); + if (ret != Z_STREAM_END && ret != Z_OK) { + qemu_free(out_buf); + deflateEnd(&strm); + return -1; + } + out_len = strm.next_out - out_buf; + + deflateEnd(&strm); + + if (ret != Z_STREAM_END || out_len >= s->cluster_size) { + /* could not compress: write normal cluster */ + qcow_write(bs, sector_num, buf, s->cluster_sectors); + } else { + cluster_offset = get_cluster_offset(bs, sector_num << 9, 2, + out_len, 0, 0); + cluster_offset &= s->cluster_offset_mask; + lseek64(s->fd, cluster_offset, SEEK_SET); + if (write(s->fd, out_buf, out_len) != out_len) { + qemu_free(out_buf); + return -1; + } + } + + qemu_free(out_buf); + return 0; +} + +BlockDriver bdrv_qcow = { + "qcow", + sizeof(BDRVQcowState), + qcow_probe, + qcow_open, + qcow_read, + qcow_write, + qcow_close, + qcow_create, + qcow_is_allocated, + qcow_set_key, +}; + + |