crypto: add support for gcrypt's native XTS impl

Libgcrypt 1.8.0 added support for the XTS mode. Use this because long
term we wish to delete QEMU's XTS impl to avoid carrying private crypto
algorithm impls.

As an added benefit, using this improves performance from 531 MB/sec to
670 MB/sec, since we are avoiding several layers of function call
indirection.

This is even more noticable with the gcrypt builds in Fedora or RHEL-8
which have a non-upstream patch for FIPS mode which does mutex locking.
This is catastrophic for encryption performance with small block sizes,
meaning this patch improves encryption from 240 MB/sec to 670 MB/sec.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

4 files changed, 88 insertions, 35 deletions

diff --git a/configure b/configure
index 145fcab..d1e9e45 100755
--- a/configure
+++ b/configure
@@ -474,6 +474,8 @@ gnutls=""
 nettle=""
 gcrypt=""
 gcrypt_hmac="no"
+gcrypt_xts="no"
+qemu_private_xts="yes"
 auth_pam=""
 vte=""
 virglrenderer=""
@@ -2911,6 +2913,18 @@ EOF
         if compile_prog "$gcrypt_cflags" "$gcrypt_libs" ; then
             gcrypt_hmac=yes
         fi
+        cat > $TMPC << EOF
+#include <gcrypt.h>
+int main(void) {
+  gcry_cipher_hd_t handle;
+  gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_XTS, 0);
+  return 0;
+}
+EOF
+        if compile_prog "$gcrypt_cflags" "$gcrypt_libs" ; then
+            gcrypt_xts=yes
+            qemu_private_xts=no
+        fi
     elif test "$gcrypt" = "yes"; then
         feature_not_found "gcrypt" "Install gcrypt devel >= 1.5.0"
     else
@@ -6326,6 +6340,11 @@ echo "VTE support       $vte $(echo_version $vte $vteversion)"
 echo "TLS priority      $tls_priority"
 echo "GNUTLS support    $gnutls"
 echo "libgcrypt         $gcrypt"
+if test "$gcrypt" = "yes"
+then
+   echo "  hmac            $gcrypt_hmac"
+   echo "  XTS             $gcrypt_xts"
+fi
 echo "nettle            $nettle $(echo_version $nettle $nettle_version)"
 echo "libtasn1          $tasn1"
 echo "PAM               $auth_pam"
@@ -6804,6 +6823,9 @@ if test "$nettle" = "yes" ; then
   echo "CONFIG_NETTLE=y" >> $config_host_mak
   echo "CONFIG_NETTLE_VERSION_MAJOR=${nettle_version%%.*}" >> $config_host_mak
 fi
+if test "$qemu_private_xts" = "yes" ; then
+  echo "CONFIG_QEMU_PRIVATE_XTS=y" >> $config_host_mak
+fi
 if test "$tasn1" = "yes" ; then
   echo "CONFIG_TASN1=y" >> $config_host_mak
 fi
diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index 7fe2fa9..cdb01f9 100644
--- a/crypto/Makefile.objs
+++ b/crypto/Makefile.objs
@@ -31,7 +31,7 @@ crypto-obj-y += ivgen-essiv.o
 crypto-obj-y += ivgen-plain.o
 crypto-obj-y += ivgen-plain64.o
 crypto-obj-y += afsplit.o
-crypto-obj-y += xts.o
+crypto-obj-$(CONFIG_QEMU_PRIVATE_XTS) += xts.o
 crypto-obj-y += block.o
 crypto-obj-y += block-qcow.o
 crypto-obj-y += block-luks.o
diff --git a/crypto/cipher-gcrypt.c b/crypto/cipher-gcrypt.c
index 5cece9b..2864099 100644
--- a/crypto/cipher-gcrypt.c
+++ b/crypto/cipher-gcrypt.c
@@ -19,7 +19,9 @@
  */
 
 #include "qemu/osdep.h"
+#ifdef CONFIG_QEMU_PRIVATE_XTS
 #include "crypto/xts.h"
+#endif
 #include "cipherpriv.h"
 
 #include <gcrypt.h>
@@ -59,10 +61,12 @@ bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg,
 typedef struct QCryptoCipherGcrypt QCryptoCipherGcrypt;
 struct QCryptoCipherGcrypt {
     gcry_cipher_hd_t handle;
-    gcry_cipher_hd_t tweakhandle;
     size_t blocksize;
+#ifdef CONFIG_QEMU_PRIVATE_XTS
+    gcry_cipher_hd_t tweakhandle;
     /* Initialization vector or Counter */
     uint8_t *iv;
+#endif
 };
 
 static void
@@ -74,10 +78,12 @@ qcrypto_gcrypt_cipher_free_ctx(QCryptoCipherGcrypt *ctx,
     }
 
     gcry_cipher_close(ctx->handle);
+#ifdef CONFIG_QEMU_PRIVATE_XTS
     if (mode == QCRYPTO_CIPHER_MODE_XTS) {
         gcry_cipher_close(ctx->tweakhandle);
     }
     g_free(ctx->iv);
+#endif
     g_free(ctx);
 }
 
@@ -94,8 +100,14 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
 
     switch (mode) {
     case QCRYPTO_CIPHER_MODE_ECB:
+        gcrymode = GCRY_CIPHER_MODE_ECB;
+        break;
     case QCRYPTO_CIPHER_MODE_XTS:
+#ifdef CONFIG_QEMU_PRIVATE_XTS
         gcrymode = GCRY_CIPHER_MODE_ECB;
+#else
+        gcrymode = GCRY_CIPHER_MODE_XTS;
+#endif
         break;
     case QCRYPTO_CIPHER_MODE_CBC:
         gcrymode = GCRY_CIPHER_MODE_CBC;
@@ -172,6 +184,7 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
                    gcry_strerror(err));
         goto error;
     }
+#ifdef CONFIG_QEMU_PRIVATE_XTS
     if (mode == QCRYPTO_CIPHER_MODE_XTS) {
         err = gcry_cipher_open(&ctx->tweakhandle, gcryalg, gcrymode, 0);
         if (err != 0) {
@@ -180,6 +193,7 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
             goto error;
         }
     }
+#endif
 
     if (alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
         /* We're using standard DES cipher from gcrypt, so we need
@@ -191,6 +205,7 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
         g_free(rfbkey);
         ctx->blocksize = 8;
     } else {
+#ifdef CONFIG_QEMU_PRIVATE_XTS
         if (mode == QCRYPTO_CIPHER_MODE_XTS) {
             nkey /= 2;
             err = gcry_cipher_setkey(ctx->handle, key, nkey);
@@ -201,8 +216,11 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
             }
             err = gcry_cipher_setkey(ctx->tweakhandle, key + nkey, nkey);
         } else {
+#endif
             err = gcry_cipher_setkey(ctx->handle, key, nkey);
+#ifdef CONFIG_QEMU_PRIVATE_XTS
         }
+#endif
         if (err != 0) {
             error_setg(errp, "Cannot set key: %s",
                        gcry_strerror(err));
@@ -228,6 +246,7 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
         }
     }
 
+#ifdef CONFIG_QEMU_PRIVATE_XTS
     if (mode == QCRYPTO_CIPHER_MODE_XTS) {
         if (ctx->blocksize != XTS_BLOCK_SIZE) {
             error_setg(errp,
@@ -237,6 +256,7 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
         }
         ctx->iv = g_new0(uint8_t, ctx->blocksize);
     }
+#endif
 
     return ctx;
 
@@ -253,6 +273,7 @@ qcrypto_gcrypt_cipher_ctx_free(QCryptoCipher *cipher)
 }
 
 
+#ifdef CONFIG_QEMU_PRIVATE_XTS
 static void qcrypto_gcrypt_xts_encrypt(const void *ctx,
                                        size_t length,
                                        uint8_t *dst,
@@ -272,6 +293,7 @@ static void qcrypto_gcrypt_xts_decrypt(const void *ctx,
     err = gcry_cipher_decrypt((gcry_cipher_hd_t)ctx, dst, length, src, length);
     g_assert(err == 0);
 }
+#endif
 
 static int
 qcrypto_gcrypt_cipher_encrypt(QCryptoCipher *cipher,
@@ -289,20 +311,23 @@ qcrypto_gcrypt_cipher_encrypt(QCryptoCipher *cipher,
         return -1;
     }
 
+#ifdef CONFIG_QEMU_PRIVATE_XTS
     if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
         xts_encrypt(ctx->handle, ctx->tweakhandle,
                     qcrypto_gcrypt_xts_encrypt,
                     qcrypto_gcrypt_xts_decrypt,
                     ctx->iv, len, out, in);
-    } else {
-        err = gcry_cipher_encrypt(ctx->handle,
-                                  out, len,
-                                  in, len);
-        if (err != 0) {
-            error_setg(errp, "Cannot encrypt data: %s",
-                       gcry_strerror(err));
-            return -1;
-        }
+        return 0;
+    }
+#endif
+
+    err = gcry_cipher_encrypt(ctx->handle,
+                              out, len,
+                              in, len);
+    if (err != 0) {
+        error_setg(errp, "Cannot encrypt data: %s",
+                   gcry_strerror(err));
+        return -1;
     }
 
     return 0;
@@ -325,20 +350,23 @@ qcrypto_gcrypt_cipher_decrypt(QCryptoCipher *cipher,
         return -1;
     }
 
+#ifdef CONFIG_QEMU_PRIVATE_XTS
     if (cipher->mode == QCRYPTO_CIPHER_MODE_XTS) {
         xts_decrypt(ctx->handle, ctx->tweakhandle,
                     qcrypto_gcrypt_xts_encrypt,
                     qcrypto_gcrypt_xts_decrypt,
                     ctx->iv, len, out, in);
-    } else {
-        err = gcry_cipher_decrypt(ctx->handle,
-                                  out, len,
-                                  in, len);
-        if (err != 0) {
-            error_setg(errp, "Cannot decrypt data: %s",
-                       gcry_strerror(err));
-            return -1;
-        }
+        return 0;
+    }
+#endif
+
+    err = gcry_cipher_decrypt(ctx->handle,
+                              out, len,
+                              in, len);
+    if (err != 0) {
+        error_setg(errp, "Cannot decrypt data: %s",
+                   gcry_strerror(err));
+        return -1;
     }
 
     return 0;
@@ -358,24 +386,27 @@ qcrypto_gcrypt_cipher_setiv(QCryptoCipher *cipher,
         return -1;
     }
 
+#ifdef CONFIG_QEMU_PRIVATE_XTS
     if (ctx->iv) {
         memcpy(ctx->iv, iv, niv);
-    } else {
-        if (cipher->mode == QCRYPTO_CIPHER_MODE_CTR) {
-            err = gcry_cipher_setctr(ctx->handle, iv, niv);
-            if (err != 0) {
-                error_setg(errp, "Cannot set Counter: %s",
+        return 0;
+    }
+#endif
+
+    if (cipher->mode == QCRYPTO_CIPHER_MODE_CTR) {
+        err = gcry_cipher_setctr(ctx->handle, iv, niv);
+        if (err != 0) {
+            error_setg(errp, "Cannot set Counter: %s",
                        gcry_strerror(err));
-                return -1;
-            }
-        } else {
-            gcry_cipher_reset(ctx->handle);
-            err = gcry_cipher_setiv(ctx->handle, iv, niv);
-            if (err != 0) {
-                error_setg(errp, "Cannot set IV: %s",
+            return -1;
+        }
+    } else {
+        gcry_cipher_reset(ctx->handle);
+        err = gcry_cipher_setiv(ctx->handle, iv, niv);
+        if (err != 0) {
+            error_setg(errp, "Cannot set IV: %s",
                        gcry_strerror(err));
-                return -1;
-            }
+            return -1;
         }
     }
 
diff --git a/tests/Makefile.include b/tests/Makefile.include
index 09e5b41..4efdd0c 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -140,7 +140,7 @@ check-unit-y += tests/test-base64$(EXESUF)
 check-unit-$(call land,$(CONFIG_BLOCK),$(if $(CONFIG_NETTLE),y,$(CONFIG_GCRYPT))) += tests/test-crypto-pbkdf$(EXESUF)
 check-unit-$(CONFIG_BLOCK) += tests/test-crypto-ivgen$(EXESUF)
 check-unit-$(CONFIG_BLOCK)  += tests/test-crypto-afsplit$(EXESUF)
-check-unit-$(CONFIG_BLOCK)  += tests/test-crypto-xts$(EXESUF)
+check-unit-$(if $(CONFIG_BLOCK),$(CONFIG_QEMU_PRIVATE_XTS)) += tests/test-crypto-xts$(EXESUF)
 check-unit-$(CONFIG_BLOCK)  += tests/test-crypto-block$(EXESUF)
 check-unit-y += tests/test-logging$(EXESUF)
 check-unit-$(call land,$(CONFIG_BLOCK),$(CONFIG_REPLICATION)) += tests/test-replication$(EXESUF)