Re: [Qemu-devel] [PATCH for-2.10 14/19] crypto: cipher: add af_alg cipher support

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Apr 10, 2017 at 05:00:52PM +0800, Longpeng(Mike) wrote:
> Adds afalg-backend cipher support: introduces some private APIs
> firstly, and then intergrates them into qcrypto_cipher_afalg_driver.
> 
> Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
> ---
>  crypto/Makefile.objs        |   1 +
>  crypto/cipher-afalg.c       | 229 ++++++++++++++++++++++++++++++++++++++++++++
>  crypto/cipher.c             |  30 +++++-
>  include/crypto/afalg-comm.h |  11 +++
>  include/crypto/cipher.h     |   7 ++
>  tests/test-crypto-cipher.c  |  10 +-
>  6 files changed, 286 insertions(+), 2 deletions(-)
>  create mode 100644 crypto/cipher-afalg.c
> 

> diff --git a/crypto/cipher-afalg.c b/crypto/cipher-afalg.c
> new file mode 100644
> index 0000000..2da972c
> --- /dev/null
> +++ b/crypto/cipher-afalg.c
> @@ -0,0 +1,229 @@
> +/*
> + * QEMU Crypto af_alg-backend cipher 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/sockets.h"
> +#include "qemu-common.h"
> +#include "qapi/error.h"
> +#include "crypto/cipher.h"
> +#include "crypto/afalg-comm.h"
> +#include <linux/if_alg.h>
> +
> +static int afalg_cipher_format_name(QCryptoCipherAlgorithm alg,
> +                             QCryptoCipherMode mode,
> +                             AfalgSocketAddress *afalg)
> +{
> +    const char *alg_name = NULL;
> +    const char *mode_name = NULL;
> +
> +    switch (alg) {
> +    case QCRYPTO_CIPHER_ALG_AES_128:
> +    case QCRYPTO_CIPHER_ALG_AES_192:
> +    case QCRYPTO_CIPHER_ALG_AES_256:
> +        alg_name = "aes";
> +        break;
> +    case QCRYPTO_CIPHER_ALG_CAST5_128:
> +        alg_name = "cast5";
> +        break;
> +    case QCRYPTO_CIPHER_ALG_SERPENT_128:
> +    case QCRYPTO_CIPHER_ALG_SERPENT_192:
> +    case QCRYPTO_CIPHER_ALG_SERPENT_256:
> +        alg_name = "serpent";
> +        break;
> +    case QCRYPTO_CIPHER_ALG_TWOFISH_128:
> +    case QCRYPTO_CIPHER_ALG_TWOFISH_192:
> +    case QCRYPTO_CIPHER_ALG_TWOFISH_256:
> +        alg_name = "twofish";
> +        break;
> +
> +    default:
> +        return -1;
> +    }

You should pass Error **errp into this method & set error in
the default case.

> +
> +    mode_name = QCryptoCipherMode_lookup[mode];
> +    afalg->name = (char *)g_new0(int8_t, SALG_NAME_LEN_MAX);
> +    sprintf(afalg->name, "%s(%s)", mode_name, alg_name);

You're printing into a fixed length buffer here with no bounds
checking. Please use snprintf and report an error if it is too
large to fit.

> +
> +    return 0;
> +}
> +
> +QCryptoAfalg *afalg_cipher_ctx_new(QCryptoCipherAlgorithm alg,
> +                                   QCryptoCipherMode mode,
> +                                   const uint8_t *key,
> +                                   size_t nkey, Error **errp)
> +{
> +    SocketAddress *saddr = NULL;
> +    QCryptoAfalg *afalg = NULL;
> +    size_t except_niv = 0;
> +    int ret = 0;
> +
> +    saddr = g_new0(SocketAddress, 1);
> +    saddr->u.afalg.data = g_new0(AfalgSocketAddress, 1);
> +    saddr->type = SOCKET_ADDRESS_KIND_AFALG;
> +    ret = afalg_cipher_format_name(alg, mode, saddr->u.afalg.data);
> +    if (ret != 0) {
> +        error_setg(errp, "Unsupported cipher mode %s",
> +                   QCryptoCipherMode_lookup[mode]);
> +        goto error;
> +    }
> +    afalg_comm_format_type(saddr->u.afalg.data, ALG_TYPE_CIPHER);
> +
> +    afalg = afalg_comm_alloc(saddr);
> +    if (!afalg) {
> +        error_setg(errp, "Alloc QCryptoAfalg object failed");

The afalg_comm_alloc() function should take an 'Error **errp' so it can
report a more specific message.

> +        goto error;
> +    }
> +
> +    /* setkey */
> +    ret = qemu_setsockopt(afalg->tfmfd, SOL_ALG, ALG_SET_KEY, key,
> +                          nkey);
> +    if (ret != 0) {
> +        error_setg(errp, "Afalg setkey failed");

error_setg_errno()

> +        goto error;
> +    }
> +
> +    /* prepare msg header */
> +    afalg->msg = g_new0(struct msghdr, 1);
> +    afalg->msg->msg_controllen += CMSG_SPACE(ALG_OPTYPE_LEN);
> +    except_niv = qcrypto_cipher_get_iv_len(alg, mode);
> +    if (except_niv) {
> +        afalg->msg->msg_controllen += CMSG_SPACE(ALG_MSGIV_LEN(except_niv));
> +    }
> +    afalg->msg->msg_control = g_new0(uint8_t, afalg->msg->msg_controllen);
> +
> +    /* We use 1st msghdr for crypto-info and 2nd msghdr for IV-info */
> +    afalg->cmsg = CMSG_FIRSTHDR(afalg->msg);
> +    afalg->cmsg->cmsg_level = SOL_ALG;
> +    afalg->cmsg->cmsg_type = ALG_SET_OP;
> +    afalg->cmsg->cmsg_len = CMSG_SPACE(ALG_OPTYPE_LEN);
> +
> +cleanup:
> +    g_free(saddr->u.afalg.data->type);
> +    g_free(saddr->u.afalg.data->name);
> +    g_free(saddr->u.afalg.data);
> +    g_free(saddr);
> +    return afalg;
> +
> +error:
> +    afalg_comm_free(afalg);
> +    afalg = NULL;
> +    goto cleanup;
> +}
> +
> +static int afalg_cipher_setiv(QCryptoCipher *cipher,
> +                               const uint8_t *iv,
> +                               size_t niv, Error **errp)
> +{
> +    struct af_alg_iv *alg_iv = NULL;
> +    QCryptoAfalg *afalg = cipher->opaque;
> +
> +    /* move ->cmsg to next msghdr, for IV-info */
> +    afalg->cmsg = CMSG_NXTHDR(afalg->msg, afalg->cmsg);
> +
> +    /* build setiv msg */
> +    afalg->cmsg->cmsg_level = SOL_ALG;
> +    afalg->cmsg->cmsg_type = ALG_SET_IV;
> +    afalg->cmsg->cmsg_len = CMSG_SPACE(ALG_MSGIV_LEN(niv));
> +    alg_iv = (struct af_alg_iv *)CMSG_DATA(afalg->cmsg);
> +    alg_iv->ivlen = niv;
> +    memcpy(alg_iv->iv, iv, niv);
> +
> +    return 0;
> +}
> +
> +static int afalg_cipher_op(QCryptoAfalg *afalg,
> +                           const void *in, void *out,
> +                           size_t len, bool do_encrypt)
> +{
> +    uint32_t *type = NULL;
> +    struct iovec iov;
> +    size_t ret, done = 0;
> +    uint32_t origin_contorllen;
> +
> +    origin_contorllen = afalg->msg->msg_controllen;
> +    /* movev ->cmsg to first header, for crypto-info */
> +    afalg->cmsg = CMSG_FIRSTHDR(afalg->msg);
> +
> +    /* build encrypt msg */
> +    afalg->msg->msg_iov = &iov;
> +    afalg->msg->msg_iovlen = 1;
> +    type = (uint32_t *)CMSG_DATA(afalg->cmsg);
> +    if (do_encrypt) {
> +        *type = ALG_OP_ENCRYPT;
> +    } else {
> +        *type = ALG_OP_DECRYPT;
> +    }
> +
> +    do {
> +        iov.iov_base = (void *)in + done;
> +        iov.iov_len = len - done;
> +
> +        /* send info to AF_ALG core */
> +        ret = sendmsg(afalg->opfd, afalg->msg, 0);
> +        if (ret == -1) {
> +            return -1;
> +        }

error_setg_errno() to report a real error message

> +
> +        /* encrypto && get result */
> +        if (ret != read(afalg->opfd, out, ret)) {

Again, error_setg_errno()

> +            return -1;
> +        }
> +
> +        /* do not update IV for following chunks */
> +        afalg->msg->msg_controllen = 0;
> +        done += ret;
> +    } while (done < len);
> +
> +    afalg->msg->msg_controllen = origin_contorllen;
> +
> +    return 0;
> +}
> +
> +static int afalg_cipher_encrypt(QCryptoCipher *cipher,
> +                                const void *in, void *out,
> +                                size_t len, Error **errp)
> +{
> +    int ret;
> +
> +    ret = afalg_cipher_op(cipher->opaque, in, out, len, 1);
> +    if (ret == -1) {
> +        error_setg(errp, "Afalg cipher encrypt failed");

Don't report an error here - make afalg_cipher_op() report
it

> +    }
> +
> +    return ret;
> +}
> +
> +static int afalg_cipher_decrypt(QCryptoCipher *cipher,
> +                                const void *in, void *out,
> +                                size_t len, Error **errp)
> +{
> +    int ret;
> +
> +    ret = afalg_cipher_op(cipher->opaque, in, out, len, 0);
> +    if (ret == -1) {
> +        error_setg(errp, "Afalg cipher decrypt failed");
> +    }
> +
> +    return ret;
> +}
> +
> +static void afalg_comm_ctx_free(QCryptoCipher *cipher)
> +{
> +    afalg_comm_free(cipher->opaque);
> +}


All methods in this file should be named 'qcrypto_afalg_...'

> +
> +struct QCryptoCipherDriver qcrypto_cipher_afalg_driver = {
> +    .cipher_encrypt = afalg_cipher_encrypt,
> +    .cipher_decrypt = afalg_cipher_decrypt,
> +    .cipher_setiv = afalg_cipher_setiv,
> +    .cipher_free = afalg_comm_ctx_free,
> +};




Regards,
Daniel
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