crypto: support multiple threads accessing one QCryptoBlock

The two thing that should be handled are cipher and ivgen. For ivgen
the solution is just mutex, as iv calculations should not be long in
comparison with encryption/decryption. And for cipher let's just keep
per-thread ciphers.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

block/crypto.c

@@ -229,6 +229,7 @@ static int block_crypto_open_generic(QCryptoBlockFormat format,
                                        block_crypto_read_func,
                                        bs,
                                        cflags,
+                                       1,
                                        errp);
 
     if (!crypto->block) {

block/qcow.c

@@ -213,7 +213,7 @@ static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
             }
             s->crypto = qcrypto_block_open(crypto_opts, "encrypt.",
-                                           NULL, NULL, cflags, errp);
+                                           NULL, NULL, cflags, 1, errp);
             if (!s->crypto) {
                 ret = -EINVAL;
                 goto fail;

block/qcow2.c

@@ -294,7 +294,7 @@ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset,
             }
             s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
                                            qcow2_crypto_hdr_read_func,
-                                           bs, cflags, errp);
+                                           bs, cflags, 1, errp);
             if (!s->crypto) {
                 return -EINVAL;
             }
@@ -1445,7 +1445,7 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options,
                 cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
             }
             s->crypto = qcrypto_block_open(s->crypto_opts, "encrypt.",
-                                           NULL, NULL, cflags, errp);
+                                           NULL, NULL, cflags, 1, errp);
             if (!s->crypto) {
                 ret = -EINVAL;
                 goto fail;

crypto/block-luks.c

@@ -636,6 +636,7 @@ qcrypto_block_luks_open(QCryptoBlock *block,
                         QCryptoBlockReadFunc readfunc,
                         void *opaque,
                         unsigned int flags,
+                        size_t n_threads,
                         Error **errp)
 {
     QCryptoBlockLUKS *luks;
@@ -836,11 +837,10 @@ qcrypto_block_luks_open(QCryptoBlock *block,
             goto fail;
         }
 
-        block->cipher = qcrypto_cipher_new(cipheralg,
-                                           ciphermode,
-                                           masterkey, masterkeylen,
-                                           errp);
-        if (!block->cipher) {
+        ret = qcrypto_block_init_cipher(block, cipheralg, ciphermode,
+                                        masterkey, masterkeylen, n_threads,
+                                        errp);
+        if (ret < 0) {
             ret = -ENOTSUP;
             goto fail;
         }
@@ -863,7 +863,7 @@ qcrypto_block_luks_open(QCryptoBlock *block,
 
  fail:
     g_free(masterkey);
-    qcrypto_cipher_free(block->cipher);
+    qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
     g_free(luks);
     g_free(password);
@@ -1030,11 +1030,9 @@ qcrypto_block_luks_create(QCryptoBlock *block,
 
 
     /* Setup the block device payload encryption objects */
-    block->cipher = qcrypto_cipher_new(luks_opts.cipher_alg,
-                                       luks_opts.cipher_mode,
-                                       masterkey, luks->header.key_bytes,
-                                       errp);
-    if (!block->cipher) {
+    if (qcrypto_block_init_cipher(block, luks_opts.cipher_alg,
+                                  luks_opts.cipher_mode, masterkey,
+                                  luks->header.key_bytes, 1, errp) < 0) {
         goto error;
     }
 
@@ -1341,7 +1339,7 @@ qcrypto_block_luks_create(QCryptoBlock *block,
     qcrypto_ivgen_free(ivgen);
     qcrypto_cipher_free(cipher);
 
-    qcrypto_cipher_free(block->cipher);
+    qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
 
     g_free(luks);

crypto/block-qcow.c

@@ -44,6 +44,7 @@ qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED,
 static int
 qcrypto_block_qcow_init(QCryptoBlock *block,
                         const char *keysecret,
+                        size_t n_threads,
                         Error **errp)
 {
     char *password;
@@ -71,11 +72,11 @@ qcrypto_block_qcow_init(QCryptoBlock *block,
         goto fail;
     }
 
-    block->cipher = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_128,
-                                       QCRYPTO_CIPHER_MODE_CBC,
-                                       keybuf, G_N_ELEMENTS(keybuf),
-                                       errp);
-    if (!block->cipher) {
+    ret = qcrypto_block_init_cipher(block, QCRYPTO_CIPHER_ALG_AES_128,
+                                    QCRYPTO_CIPHER_MODE_CBC,
+                                    keybuf, G_N_ELEMENTS(keybuf),
+                                    n_threads, errp);
+    if (ret < 0) {
         ret = -ENOTSUP;
         goto fail;
     }
@@ -86,7 +87,7 @@ qcrypto_block_qcow_init(QCryptoBlock *block,
     return 0;
 
  fail:
-    qcrypto_cipher_free(block->cipher);
+    qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
     return ret;
 }
@@ -99,6 +100,7 @@ qcrypto_block_qcow_open(QCryptoBlock *block,
                         QCryptoBlockReadFunc readfunc G_GNUC_UNUSED,
                         void *opaque G_GNUC_UNUSED,
                         unsigned int flags,
+                        size_t n_threads,
                         Error **errp)
 {
     if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) {
@@ -112,8 +114,8 @@ qcrypto_block_qcow_open(QCryptoBlock *block,
                        optprefix ? optprefix : "");
             return -1;
         }
-        return qcrypto_block_qcow_init(block,
-                                       options->u.qcow.key_secret, errp);
+        return qcrypto_block_qcow_init(block, options->u.qcow.key_secret,
+                                       n_threads, errp);
     }
 }
 
@@ -133,7 +135,7 @@ qcrypto_block_qcow_create(QCryptoBlock *block,
         return -1;
     }
     /* QCow2 has no special header, since everything is hardwired */
-    return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, errp);
+    return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, 1, errp);
 }
 
 

crypto/block.c

@@ -52,6 +52,7 @@ QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
                                  QCryptoBlockReadFunc readfunc,
                                  void *opaque,
                                  unsigned int flags,
+                                 size_t n_threads,
                                  Error **errp)
 {
     QCryptoBlock *block = g_new0(QCryptoBlock, 1);
@@ -69,11 +70,14 @@ QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
     block->driver = qcrypto_block_drivers[options->format];
 
     if (block->driver->open(block, options, optprefix,
-                            readfunc, opaque, flags, errp) < 0) {
+                            readfunc, opaque, flags, n_threads, errp) < 0)
+    {
         g_free(block);
         return NULL;
     }
 
+    qemu_mutex_init(&block->mutex);
+
     return block;
 }
 
@@ -105,6 +109,8 @@ QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
         return NULL;
     }
 
+    qemu_mutex_init(&block->mutex);
+
     return block;
 }
 
@@ -148,12 +154,97 @@ int qcrypto_block_encrypt(QCryptoBlock *block,
 
 QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block)
 {
-    return block->cipher;
+    /* Ciphers should be accessed through pop/push method to be thread-safe.
+     * Better, they should not be accessed externally at all (note, that
+     * pop/push are static functions)
+     * This function is used only in test with one thread (it's safe to skip
+     * pop/push interface), so it's enough to assert it here:
+     */
+    assert(block->n_ciphers <= 1);
+    return block->ciphers ? block->ciphers[0] : NULL;
 }
 
 
+static QCryptoCipher *qcrypto_block_pop_cipher(QCryptoBlock *block)
+{
+    QCryptoCipher *cipher;
+
+    qemu_mutex_lock(&block->mutex);
+
+    assert(block->n_free_ciphers > 0);
+    block->n_free_ciphers--;
+    cipher = block->ciphers[block->n_free_ciphers];
+
+    qemu_mutex_unlock(&block->mutex);
+
+    return cipher;
+}
+
+
+static void qcrypto_block_push_cipher(QCryptoBlock *block,
+                                      QCryptoCipher *cipher)
+{
+    qemu_mutex_lock(&block->mutex);
+
+    assert(block->n_free_ciphers < block->n_ciphers);
+    block->ciphers[block->n_free_ciphers] = cipher;
+    block->n_free_ciphers++;
+
+    qemu_mutex_unlock(&block->mutex);
+}
+
+
+int qcrypto_block_init_cipher(QCryptoBlock *block,
+                              QCryptoCipherAlgorithm alg,
+                              QCryptoCipherMode mode,
+                              const uint8_t *key, size_t nkey,
+                              size_t n_threads, Error **errp)
+{
+    size_t i;
+
+    assert(!block->ciphers && !block->n_ciphers && !block->n_free_ciphers);
+
+    block->ciphers = g_new0(QCryptoCipher *, n_threads);
+
+    for (i = 0; i < n_threads; i++) {
+        block->ciphers[i] = qcrypto_cipher_new(alg, mode, key, nkey, errp);
+        if (!block->ciphers[i]) {
+            qcrypto_block_free_cipher(block);
+            return -1;
+        }
+        block->n_ciphers++;
+        block->n_free_ciphers++;
+    }
+
+    return 0;
+}
+
+
+void qcrypto_block_free_cipher(QCryptoBlock *block)
+{
+    size_t i;
+
+    if (!block->ciphers) {
+        return;
+    }
+
+    assert(block->n_ciphers == block->n_free_ciphers);
+
+    for (i = 0; i < block->n_ciphers; i++) {
+        qcrypto_cipher_free(block->ciphers[i]);
+    }
+
+    g_free(block->ciphers);
+    block->ciphers = NULL;
+    block->n_ciphers = block->n_free_ciphers = 0;
+}
+
 QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block)
 {
+    /* ivgen should be accessed under mutex. However, this function is used only
+     * in test with one thread, so it's enough to assert it here:
+     */
+    assert(block->n_ciphers <= 1);
     return block->ivgen;
 }
 
@@ -184,8 +275,9 @@ void qcrypto_block_free(QCryptoBlock *block)
 
     block->driver->cleanup(block);
 
-    qcrypto_cipher_free(block->cipher);
+    qcrypto_block_free_cipher(block);
     qcrypto_ivgen_free(block->ivgen);
+    qemu_mutex_destroy(&block->mutex);
     g_free(block);
 }
 
@@ -199,6 +291,7 @@ typedef int (*QCryptoCipherEncDecFunc)(QCryptoCipher *cipher,
 static int do_qcrypto_block_cipher_encdec(QCryptoCipher *cipher,
                                           size_t niv,
                                           QCryptoIVGen *ivgen,
+                                          QemuMutex *ivgen_mutex,
                                           int sectorsize,
                                           uint64_t offset,
                                           uint8_t *buf,
@@ -218,10 +311,15 @@ static int do_qcrypto_block_cipher_encdec(QCryptoCipher *cipher,
     while (len > 0) {
         size_t nbytes;
         if (niv) {
-            if (qcrypto_ivgen_calculate(ivgen,
-                                        startsector,
-                                        iv, niv,
-                                        errp) < 0) {
+            if (ivgen_mutex) {
+                qemu_mutex_lock(ivgen_mutex);
+            }
+            ret = qcrypto_ivgen_calculate(ivgen, startsector, iv, niv, errp);
+            if (ivgen_mutex) {
+                qemu_mutex_unlock(ivgen_mutex);
+            }
+
+            if (ret < 0) {
                 goto cleanup;
             }
 
@@ -258,7 +356,7 @@ int qcrypto_block_cipher_decrypt_helper(QCryptoCipher *cipher,
                                         size_t len,
                                         Error **errp)
 {
-    return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, sectorsize,
+    return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, NULL, sectorsize,
                                           offset, buf, len,
                                           qcrypto_cipher_decrypt, errp);
 }
@@ -273,12 +371,11 @@ int qcrypto_block_cipher_encrypt_helper(QCryptoCipher *cipher,
                                         size_t len,
                                         Error **errp)
 {
-    return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, sectorsize,
+    return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, NULL, sectorsize,
                                           offset, buf, len,
                                           qcrypto_cipher_encrypt, errp);
 }
 
-
 int qcrypto_block_decrypt_helper(QCryptoBlock *block,
                                  int sectorsize,
                                  uint64_t offset,
@@ -286,12 +383,17 @@ int qcrypto_block_decrypt_helper(QCryptoBlock *block,
                                  size_t len,
                                  Error **errp)
 {
-    return do_qcrypto_block_cipher_encdec(block->cipher, block->niv,
-                                          block->ivgen,
-                                          sectorsize, offset, buf, len,
-                                          qcrypto_cipher_decrypt, errp);
-}
+    int ret;
+    QCryptoCipher *cipher = qcrypto_block_pop_cipher(block);
 
+    ret = do_qcrypto_block_cipher_encdec(cipher, block->niv, block->ivgen,
+                                         &block->mutex, sectorsize, offset, buf,
+                                         len, qcrypto_cipher_decrypt, errp);
+
+    qcrypto_block_push_cipher(block, cipher);
+
+    return ret;
+}
 
 int qcrypto_block_encrypt_helper(QCryptoBlock *block,
                                  int sectorsize,
@@ -300,8 +402,14 @@ int qcrypto_block_encrypt_helper(QCryptoBlock *block,
                                  size_t len,
                                  Error **errp)
 {
-    return do_qcrypto_block_cipher_encdec(block->cipher, block->niv,
-                                          block->ivgen,
-                                          sectorsize, offset, buf, len,
-                                          qcrypto_cipher_encrypt, errp);
+    int ret;
+    QCryptoCipher *cipher = qcrypto_block_pop_cipher(block);
+
+    ret = do_qcrypto_block_cipher_encdec(cipher, block->niv, block->ivgen,
+                                         &block->mutex, sectorsize, offset, buf,
+                                         len, qcrypto_cipher_encrypt, errp);
+
+    qcrypto_block_push_cipher(block, cipher);
+
+    return ret;
 }

crypto/blockpriv.h

@@ -22,6 +22,7 @@
 #define QCRYPTO_BLOCKPRIV_H
 
 #include "crypto/block.h"
+#include "qemu/thread.h"
 
 typedef struct QCryptoBlockDriver QCryptoBlockDriver;
 
@@ -31,8 +32,12 @@ struct QCryptoBlock {
     const QCryptoBlockDriver *driver;
     void *opaque;
 
-    QCryptoCipher *cipher;
+    QCryptoCipher **ciphers;
+    size_t n_ciphers;
+    size_t n_free_ciphers;
     QCryptoIVGen *ivgen;
+    QemuMutex mutex;
+
     QCryptoHashAlgorithm kdfhash;
     size_t niv;
     uint64_t payload_offset; /* In bytes */
@@ -46,6 +51,7 @@ struct QCryptoBlockDriver {
                 QCryptoBlockReadFunc readfunc,
                 void *opaque,
                 unsigned int flags,
+                size_t n_threads,
                 Error **errp);
 
     int (*create)(QCryptoBlock *block,
@@ -110,4 +116,12 @@ int qcrypto_block_encrypt_helper(QCryptoBlock *block,
                                  size_t len,
                                  Error **errp);
 
+int qcrypto_block_init_cipher(QCryptoBlock *block,
+                              QCryptoCipherAlgorithm alg,
+                              QCryptoCipherMode mode,
+                              const uint8_t *key, size_t nkey,
+                              size_t n_threads, Error **errp);
+
+void qcrypto_block_free_cipher(QCryptoBlock *block);
+
 #endif /* QCRYPTO_BLOCKPRIV_H */

include/crypto/block.h

@@ -75,6 +75,7 @@ typedef enum {
  * @readfunc: callback for reading data from the volume
  * @opaque: data to pass to @readfunc
  * @flags: bitmask of QCryptoBlockOpenFlags values
+ * @n_threads: allow concurrent I/O from up to @n_threads threads
  * @errp: pointer to a NULL-initialized error object
  *
  * Create a new block encryption object for an existing
@@ -107,6 +108,7 @@ QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
                                  QCryptoBlockReadFunc readfunc,
                                  void *opaque,
                                  unsigned int flags,
+                                 size_t n_threads,
                                  Error **errp);
 
 /**

tests/test-crypto-block.c

@@ -305,6 +305,7 @@ static void test_block(gconstpointer opaque)
                              test_block_read_func,
                              &header,
                              0,
+                             1,
                              NULL);
     g_assert(blk == NULL);
 
@@ -313,6 +314,7 @@ static void test_block(gconstpointer opaque)
                              test_block_read_func,
                              &header,
                              QCRYPTO_BLOCK_OPEN_NO_IO,
+                             1,
                              &error_abort);
 
     g_assert(qcrypto_block_get_cipher(blk) == NULL);
@@ -327,6 +329,7 @@ static void test_block(gconstpointer opaque)
                              test_block_read_func,
                              &header,
                              0,
+                             1,
                              &error_abort);
     g_assert(blk);