[libvirt] [PATCH v2 3/4] qemu: Create domain master key
Daniel P. Berrange
berrange at redhat.com
Mon Apr 4 09:40:45 UTC 2016
On Tue, Mar 29, 2016 at 07:11:35PM -0400, John Ferlan wrote:
> Add a masterKey and masterKeyLen to _qemuDomainObjPrivate to store a
> random domain master key and its length in order to support the ability
> to encrypt/decrypt sensitive data shared between libvirt and qemu. The
> key will be base64 encoded and written to a file to be used by the
> command line building code to share with qemu.
>
> New API's from this patch:
>
> qemuDomainGetMasterKeyFilePath:
> Return a path to where the key is located
>
> qemuDomainWriteMasterKeyFile: (private)
> Open (create/trunc) the masterKey path and write the masterKey
>
> qemuDomainMasterKeyReadFile:
> Using the master key path, open/read the file, and store the
> masterKey and masterKeyLen. Expected use only from qemuProcessReconnect
>
> qemuDomainGenerateRandomKey: (private)
> Generate a random key using available algorithms
>
> The key is generated either from the gnutls_rnd function if it
> exists or a less cryptographically strong mechanism using
> virGenerateRandomBytes
>
> qemuDomainMasterKeyRemove:
> Remove traces of the master key, remove the *KeyFilePath
>
> qemuDomainMasterKeyCreate:
> Generate the domain master key and save the key in the location
> returned by qemuDomainGetMasterKeyFilePath.
>
> This API will first ensure the QEMU_CAPS_OBJECT_SECRET is set
> in the capabilities. If not, then there's no need to generate
> the secret or file.
>
> The creation of the key will be attempted from qemuProcessPrepareHost
> once the libDir directory structure exists.
>
> The removal of the key will handled from qemuProcessStop just prior
> to deleting the libDir tree.
>
> Since the key will not be written out to the domain object XML file,
> the qemuProcessReconnect will read the saved file and restore the
> masterKey and masterKeyLen.
>
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
> src/qemu/qemu_domain.c | 252 ++++++++++++++++++++++++++++++++++++++++++++++++
> src/qemu/qemu_domain.h | 15 +++
> src/qemu/qemu_process.c | 11 +++
> 3 files changed, 278 insertions(+)
>
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 53cb2b6..99a91d2 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -44,6 +44,12 @@
> #include "virthreadjob.h"
> #include "viratomic.h"
> #include "virprocess.h"
> +#include "virrandom.h"
> +#include "base64.h"
> +#include <gnutls/gnutls.h>
> +#if HAVE_GNUTLS_CRYPTO_H
> +# include <gnutls/crypto.h>
> +#endif
> #include "logging/log_manager.h"
>
> #include "storage/storage_driver.h"
> @@ -465,6 +471,252 @@ qemuDomainJobInfoToParams(qemuDomainJobInfoPtr jobInfo,
> }
>
>
> +/* qemuDomainGetMasterKeyFilePath:
> + * @libDir: Directory path to domain lib files
> + *
> + * Generate a path to the domain master key file for libDir.
> + * It's up to the caller to handle checking if path exists.
> + *
> + * Returns path to memory containing the name of the file. It is up to the
> + * caller to free; otherwise, NULL on failure.
> + */
> +char *
> +qemuDomainGetMasterKeyFilePath(const char *libDir)
> +{
> + if (!libDir) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("invalid path for master key file"));
> + return NULL;
> + }
> + return virFileBuildPath(libDir, "master-key.aes", NULL);
> +}
> +
> +
> +/* qemuDomainWriteMasterKeyFile:
> + * @priv: pointer to domain private object
> + *
> + * Get the desired path to the masterKey file and store it in the path.
> + *
> + * Returns 0 on success, -1 on failure with error message indicating failure
> + */
> +static int
> +qemuDomainWriteMasterKeyFile(qemuDomainObjPrivatePtr priv)
> +{
> + char *path;
> + int fd = -1;
> + int ret = -1;
> +
> + if (!(path = qemuDomainGetMasterKeyFilePath(priv->libDir)))
> + return -1;
> +
> + if ((fd = open(path, O_WRONLY|O_TRUNC|O_CREAT, 0600)) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("failed to open domain master key file for write"));
> + goto cleanup;
> + }
> +
> + if (safewrite(fd, priv->masterKey, priv->masterKeyLen) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("failed to write master key file for domain"));
> + goto cleanup;
> + }
> +
> + ret = 0;
> +
> + cleanup:
> + VIR_FORCE_CLOSE(fd);
> + VIR_FREE(path);
> +
> + return ret;
> +}
> +
> +
> +/* qemuDomainMasterKeyReadFile:
> + * @priv: pointer to domain private object
> + *
> + * Expected to be called during qemuProcessReconnect once the domain
> + * libDir has been generated through qemuStateInitialize calling
> + * virDomainObjListLoadAllConfigs which will restore the libDir path
> + * to the domain private object.
> + *
> + * This function will get the path to the master key file and if it
> + * exists, it will read the contents of the file saving it in priv->masterKey.
> + *
> + * Once the file exists, the validity checks may cause failures; however,
> + * if the file doesn't exist or the capability doesn't exist, we just
> + * return (mostly) quietly.
> + *
> + * Returns 0 on success or lack of capability
> + * -1 on failure with error message indicating failure
> + */
> +int
> +qemuDomainMasterKeyReadFile(qemuDomainObjPrivatePtr priv)
> +{
> + char *path;
> + int fd = -1;
> + uint8_t *masterKey = NULL;
> + ssize_t masterKeyLen = 0;
> +
> + /* If we don't have the capability, then do nothing. */
> + if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_OBJECT_SECRET))
> + return 0;
> +
> + if (!(path = qemuDomainGetMasterKeyFilePath(priv->libDir)))
> + return -1;
> +
> + if (!virFileExists(path)) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("domain master key file doesn't exist in %s"),
> + priv->libDir);
> + goto error;
> + }
> +
> + if ((fd = open(path, O_RDONLY)) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("failed to open domain master key file for read"));
> + goto error;
> + }
> +
> + if (VIR_ALLOC_N(masterKey, 1024) < 0)
> + goto error;
> +
> + if ((masterKeyLen = saferead(fd, masterKey, 1024)) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> + _("unable to read domain master key file"));
> + goto error;
> + }
> +
> + if (masterKeyLen != QEMU_DOMAIN_MASTER_KEY_LEN) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("invalid master key read, size=%zd"), masterKeyLen);
> + goto error;
> + }
> +
> + masterKey[masterKeyLen] = '\0';
> + ignore_value(VIR_REALLOC_N_QUIET(masterKey, masterKeyLen + 1));
We're storing the key as raw binary data, so NUL terminating
it doesn't make any sense - it may already contain embedded
NULs and so nothing should try strlen() on it. So just drop
that extra NUL byte,
> + priv->masterKey = masterKey;
> + priv->masterKeyLen = masterKeyLen;
> +
> + VIR_FORCE_CLOSE(fd);
> + VIR_FREE(path);
> +
> + return 0;
> +
> + error:
> + if (masterKeyLen > 0)
> + memset(masterKey, 0, masterKeyLen);
> + VIR_FREE(masterKey);
> +
> + VIR_FORCE_CLOSE(fd);
> + VIR_FREE(path);
> +
> + return -1;
> +}
> +
ACK with that fix above
Regards,
Daniel
--
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