crypto: introduce some common functions for af_alg backend

The AF_ALG socket family is the userspace interface for linux
crypto API, this patch adds af_alg family support and some common
functions for af_alg backend. It'll be used by afalg-backend crypto
latter.

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>

Maintainer: modified to report an error if AF_ALG is requested
but cannot be supported

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

3 files changed, 171 insertions, 0 deletions

diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index 1f749f2087..2be5a3aa1c 100644
--- a/crypto/Makefile.objs
+++ b/crypto/Makefile.objs
@@ -10,6 +10,7 @@ crypto-obj-$(if $(CONFIG_NETTLE),n,$(if $(CONFIG_GCRYPT_HMAC),n,y)) += hmac-glib
 crypto-obj-y += aes.o
 crypto-obj-y += desrfb.o
 crypto-obj-y += cipher.o
+crypto-obj-$(CONFIG_AF_ALG) += afalg.o
 crypto-obj-y += tlscreds.o
 crypto-obj-y += tlscredsanon.o
 crypto-obj-y += tlscredsx509.o
diff --git a/crypto/afalg.c b/crypto/afalg.c
new file mode 100644
index 0000000000..10046bb0ae
--- /dev/null
+++ b/crypto/afalg.c
@@ -0,0 +1,116 @@
+/*
+ * QEMU Crypto af_alg support
+ *
+ * Copyright (c) 2017 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ * Authors:
+ *    Longpeng(Mike) <longpeng2@huawei.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ */
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qemu/sockets.h"
+#include "qapi/error.h"
+#include "afalgpriv.h"
+
+static bool
+qcrypto_afalg_build_saddr(const char *type, const char *name,
+                          struct sockaddr_alg *salg, Error **errp)
+{
+    salg->salg_family = AF_ALG;
+
+    if (strnlen(type, SALG_TYPE_LEN_MAX) >= SALG_TYPE_LEN_MAX) {
+        error_setg(errp, "Afalg type(%s) is larger than %d bytes",
+                   type, SALG_TYPE_LEN_MAX);
+        return false;
+    }
+
+    if (strnlen(name, SALG_NAME_LEN_MAX) >= SALG_NAME_LEN_MAX) {
+        error_setg(errp, "Afalg name(%s) is larger than %d bytes",
+                   name, SALG_NAME_LEN_MAX);
+        return false;
+    }
+
+    pstrcpy((char *)salg->salg_type, SALG_TYPE_LEN_MAX, type);
+    pstrcpy((char *)salg->salg_name, SALG_NAME_LEN_MAX, name);
+
+    return true;
+}
+
+static int
+qcrypto_afalg_socket_bind(const char *type, const char *name,
+                          Error **errp)
+{
+    int sbind;
+    struct sockaddr_alg salg = {0};
+
+    if (!qcrypto_afalg_build_saddr(type, name, &salg, errp)) {
+        return -1;
+    }
+
+    sbind = qemu_socket(AF_ALG, SOCK_SEQPACKET, 0);
+    if (sbind < 0) {
+        error_setg_errno(errp, errno, "Failed to create socket");
+        return -1;
+    }
+
+    if (bind(sbind, (const struct sockaddr *)&salg, sizeof(salg)) != 0) {
+        error_setg_errno(errp, errno, "Failed to bind socket");
+        closesocket(sbind);
+        return -1;
+    }
+
+    return sbind;
+}
+
+QCryptoAFAlg *
+qcrypto_afalg_comm_alloc(const char *type, const char *name,
+                         Error **errp)
+{
+    QCryptoAFAlg *afalg;
+
+    afalg = g_new0(QCryptoAFAlg, 1);
+    /* initilize crypto API socket */
+    afalg->opfd = -1;
+    afalg->tfmfd = qcrypto_afalg_socket_bind(type, name, errp);
+    if (afalg->tfmfd == -1) {
+        goto error;
+    }
+
+    afalg->opfd = qemu_accept(afalg->tfmfd, NULL, 0);
+    if (afalg->opfd == -1) {
+        error_setg_errno(errp, errno, "Failed to accept socket");
+        goto error;
+    }
+
+    return afalg;
+
+error:
+    qcrypto_afalg_comm_free(afalg);
+    return NULL;
+}
+
+void qcrypto_afalg_comm_free(QCryptoAFAlg *afalg)
+{
+    if (!afalg) {
+        return;
+    }
+
+    if (afalg->msg) {
+        g_free(afalg->msg->msg_control);
+        g_free(afalg->msg);
+    }
+
+    if (afalg->tfmfd != -1) {
+        closesocket(afalg->tfmfd);
+    }
+
+    if (afalg->opfd != -1) {
+        closesocket(afalg->opfd);
+    }
+
+    g_free(afalg);
+}
diff --git a/crypto/afalgpriv.h b/crypto/afalgpriv.h
new file mode 100644
index 0000000000..76118cf962
--- /dev/null
+++ b/crypto/afalgpriv.h
@@ -0,0 +1,54 @@
+/*
+ * QEMU Crypto af_alg support
+ *
+ * Copyright (c) 2017 HUAWEI TECHNOLOGIES CO., LTD.
+ *
+ * Authors:
+ *    Longpeng(Mike) <longpeng2@huawei.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * (at your option) any later version.  See the COPYING file in the
+ * top-level directory.
+ */
+
+#ifndef QCRYPTO_AFALGPRIV_H
+#define QCRYPTO_AFALGPRIV_H
+
+#include <linux/if_alg.h>
+
+#define SALG_TYPE_LEN_MAX 14
+#define SALG_NAME_LEN_MAX 64
+
+typedef struct QCryptoAFAlg QCryptoAFAlg;
+
+struct QCryptoAFAlg {
+    int tfmfd;
+    int opfd;
+    struct msghdr *msg;
+    struct cmsghdr *cmsg;
+};
+
+/**
+ * qcrypto_afalg_comm_alloc:
+ * @type: the type of crypto operation
+ * @name: the name of crypto operation
+ *
+ * Allocate a QCryptoAFAlg object and bind itself to
+ * a AF_ALG socket.
+ *
+ * Returns:
+ *  a new QCryptoAFAlg object, or NULL in error.
+ */
+QCryptoAFAlg *
+qcrypto_afalg_comm_alloc(const char *type, const char *name,
+                         Error **errp);
+
+/**
+ * afalg_comm_free:
+ * @afalg: the QCryptoAFAlg object
+ *
+ * Free the @afalg.
+ */
+void qcrypto_afalg_comm_free(QCryptoAFAlg *afalg);
+
+#endif