Add a masterKey to _qemuDomainObjPrivate to store a base64 encoded domain master key in order to support the ability to encrypt/decrypt sensitive data shared between libvirt and qemu. The base64 encoded value will be written to the domain XML file for consistency between domain restarts. Two APIs qemuDomainWriteMasterKeyFile and qemuDomainGetMasterKeyFilePath will manage the details of the file manipulation. The Get*Path API can be used in order to return a path to the master secret key file, which will be a combination of the domain's libDir (e.g. /var/lib/libvirt/qemu/domain-#-$NAME/) and a name 'master.key'. Use of the domain's libDir was chosen as opposed to a more generic /var/lib/libvirt/qemu/$NAME-master.key since it's a domain specific area rather than repeating issues found as a result of using the domain name in a file. The Get*Path API doesn't check if the libDir exists, it just generates the path. The Write*File API will be used to create the on disk master secret file once the domain lib infrastructure is generated during qemuProcessLaunch. The masterKey is generated as a series of 8 bit random numbers stored as a 32 byte string and then base64 encoded before saving in the domain private object. A separate function will generate the key as it's expected to be utilized by future patches to support the generation of the initialization vector. Object removal will clear and free the secret as well as check for the presence of the master key file and remove it if necessary (although it shouldn't be necessary by this point in time, but being extra safe). During process launch, the key value will additionally be stored in the domain libDir. This is what will be used to share the secret with qemu via a secret object. The secret file will only present while the domain is active (e.g. create at Launch, delete at Stop). During process stop, logic is added to check if the path to the domain libDir secret exists and then to clear the contents of the file before the directory tree is removed. The path will not exist for a domain already running prior to support being added for the master key and it'd be annoying to get errors indicating it doesn't exist when it was never created. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/qemu/qemu_domain.c | 158 ++++++++++++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_domain.h | 9 +++ src/qemu/qemu_process.c | 13 ++++ 3 files changed, 180 insertions(+) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 9f9fae3..507ae9e 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -23,6 +23,7 @@ #include <config.h> +#include <assert.h> #include "qemu_domain.h" #include "qemu_alias.h" #include "qemu_command.h" @@ -44,6 +45,8 @@ #include "virthreadjob.h" #include "viratomic.h" #include "virprocess.h" +#include "virrandom.h" +#include "base64.h" #include "logging/log_manager.h" #include "storage/storage_driver.h" @@ -465,6 +468,151 @@ qemuDomainJobInfoToParams(qemuDomainJobInfoPtr jobInfo, } +/* qemuDomainGetMasterKeyFilePath: + * @libDir: Directory path to domain lib files + * + * Build the name of the master key file based on valid libDir path + * + * 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", NULL); +} + + +/* qemuDomainWriteMasterKeyFile: + * @libDir: Directory path to domain lib files + * @masterKey: Key to write to the file + * + * Using the passed libDir and masterKey write the key to the master + * key file for the domain. + * + * Returns 0 on success, -1 on failure with error message indicating failure + */ +int +qemuDomainWriteMasterKeyFile(const char *libDir, + const char *masterKey) +{ + char *path; + int ret = -1; + + if (!(path = qemuDomainGetMasterKeyFilePath(libDir))) + return -1; + + if (virFileWriteStr(path, masterKey, 0600) < 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("failed to write master key file for domain")); + goto cleanup; + } + + ret = 0; + + cleanup: + VIR_FREE(path); + return ret; +} + + +/* qemuDomainGenerateRandomKey + * @nbytes: Size in bytes of random key to generate - expect multiple of 8 + * + * Generate a random key of nbytes length and return it. + * + * Returns pointer memory containing key on success, NULL on failure + */ +static unsigned char * +qemuDomainGenerateRandomKey(int nbytes) +{ + unsigned char *key; + size_t i; + + assert((nbytes % 8) == 0); + + if (VIR_ALLOC_N(key, nbytes) < 0) + return NULL; + + /* Generate a random master key based on the nbytes passed */ + for (i = 0; i < nbytes; i++) + key[i] = virRandomBits(8); + + return key; +} + + +/* + * qemuDomainMasterKeyRemove: + * @priv: Pointer to the domain private object + * + * Remove the traces of the master key, clear the heap, clear the file, + * delete the file. + */ +static void +qemuDomainMasterKeyRemove(qemuDomainObjPrivatePtr priv) +{ + char *path = NULL; + + if (!priv->masterKey) + return; + + /* Clear the heap */ + memset(priv->masterKey, 0, QEMU_DOMAIN_MASTER_KEY_LEN); + VIR_FREE(priv->masterKey); + + /* Clear and remove the file, if not already handled during process stop */ + if (priv->libDir && virFileExists(priv->libDir)) { + path = qemuDomainGetMasterKeyFilePath(priv->libDir); + if (path && virFileExists(path)) { + ignore_value(qemuDomainWriteMasterKeyFile(priv->libDir, "0")); + unlink(path); + } + } + VIR_FREE(path); +} + + +/* qemuDomainMasterKeyCreate: + * @priv: Pointer to the domain private object + * + * Generate and store as a base64 encoded value a random 32-byte key + * to be used as a secret shared with qemu to share sensative data. + * + * Returns: 0 on success, -1 w/ error message on failure + */ +static int +qemuDomainMasterKeyCreate(qemuDomainObjPrivatePtr priv) +{ + unsigned char *key = NULL; + + if (!(key = qemuDomainGenerateRandomKey(QEMU_DOMAIN_MASTER_KEY_LEN))) + goto error; + + /* base64 encode the key */ + base64_encode_alloc((const char *)key, QEMU_DOMAIN_MASTER_KEY_LEN, + &priv->masterKey); + memset(key, 0, QEMU_DOMAIN_MASTER_KEY_LEN); + VIR_FREE(key); + if (!priv->masterKey) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("failed to encode master key")); + goto error; + } + + return 0; + + error: + qemuDomainMasterKeyRemove(priv); + return -1; +} + + static virClassPtr qemuDomainDiskPrivateClass; static int @@ -574,6 +722,9 @@ qemuDomainObjPrivateAlloc(void) if (!(priv->devs = virChrdevAlloc())) goto error; + if (qemuDomainMasterKeyCreate(priv) < 0) + goto error; + priv->migMaxBandwidth = QEMU_DOMAIN_MIG_BANDWIDTH_MAX; return priv; @@ -590,6 +741,8 @@ qemuDomainObjPrivateFree(void *data) virObjectUnref(priv->qemuCaps); + qemuDomainMasterKeyRemove(priv); + virCgroupFree(&priv->cgroup); virDomainPCIAddressSetFree(priv->pciaddrs); virDomainCCWAddressSetFree(priv->ccwaddrs); @@ -746,6 +899,9 @@ qemuDomainObjPrivateXMLFormat(virBufferPtr buf, virBufferEscapeString(buf, "<channelTargetDir path='%s'/>\n", priv->channelTargetDir); + if (priv->masterKey) + virBufferAsprintf(buf, "<masterKey>%s</masterKey>\n", priv->masterKey); + return 0; } @@ -959,6 +1115,8 @@ qemuDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt, if (qemuDomainSetPrivatePathsOld(driver, vm) < 0) goto error; + priv->masterKey = virXPathString("string(./masterKey)", ctxt); + return 0; error: diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index 573968c..b24acdf 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -147,6 +147,7 @@ struct qemuDomainJobObj { typedef void (*qemuDomainCleanupCallback)(virQEMUDriverPtr driver, virDomainObjPtr vm); +# define QEMU_DOMAIN_MASTER_KEY_LEN 32 /* For a 32-byte random AES key */ typedef struct _qemuDomainObjPrivate qemuDomainObjPrivate; typedef qemuDomainObjPrivate *qemuDomainObjPrivatePtr; struct _qemuDomainObjPrivate { @@ -212,6 +213,8 @@ struct _qemuDomainObjPrivate { char *machineName; char *libDir; /* base path for per-domain files */ char *channelTargetDir; /* base path for per-domain channel targets */ + + char *masterKey; /* base64 encoded random key */ }; # define QEMU_DOMAIN_DISK_PRIVATE(disk) \ @@ -546,4 +549,10 @@ int qemuDomainSetPrivatePaths(char **domainLibDir, const char *confChannelDir, const char *domainName, int domainId); + +char *qemuDomainGetMasterKeyFilePath(const char *libDir); + +int qemuDomainWriteMasterKeyFile(const char *libDir, const char *masterKey) + ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2); + #endif /* __QEMU_DOMAIN_H__ */ diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index c332747..0784f1c 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -5141,6 +5141,10 @@ qemuProcessLaunch(virConnectPtr conn, qemuProcessMakeDir(driver, vm, priv->channelTargetDir) < 0) goto cleanup; + /* Write the masterKey to the file in libDir */ + if (qemuDomainWriteMasterKeyFile(priv->libDir, priv->masterKey) < 0) + goto cleanup; + /* now that we know it is about to start call the hook if present */ if (qemuProcessStartHook(driver, vm, VIR_HOOK_QEMU_OP_START, @@ -5583,6 +5587,7 @@ void qemuProcessStop(virQEMUDriverPtr driver, virNetDevVPortProfilePtr vport = NULL; size_t i; char *timestamp; + char *masterKeyPath = NULL; virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); qemuDomainLogContextPtr logCtxt = NULL; @@ -5668,6 +5673,13 @@ void qemuProcessStop(virQEMUDriverPtr driver, priv->monConfig = NULL; } + /* If we have a masterKeyPath, then clear the masterKey from the file + * even though it's about to be deleted, let's not leave any traces. + */ + masterKeyPath = qemuDomainGetMasterKeyFilePath(priv->libDir); + if (virFileExists(masterKeyPath)) + ignore_value(qemuDomainWriteMasterKeyFile(priv->libDir, "0")); + virFileDeleteTree(priv->libDir); virFileDeleteTree(priv->channelTargetDir); @@ -5867,6 +5879,7 @@ void qemuProcessStop(virQEMUDriverPtr driver, qemuDomainObjEndJob(driver, vm); cleanup: + VIR_FREE(masterKeyPath); if (orig_err) { virSetError(orig_err); virFreeError(orig_err); -- 2.5.0

On 03/22/2016 08:56 AM, Peter Krempa wrote: Oh right - seems so easy to think this way in retrospect... When I first started it was Write the file only if the object caps existed and write it to libDir. Chosen because qemuBuildCommandLine doesn't have the priv object, rather it seems it was preferred to pass multiple elements (monConfig, monJSON, qemuCaps, audoNodeset, libDir, channelTargetDir) instead. Even vm->def is passed instead of 'vm'. Having not always been successful banging on the door of changing what was passed to functions and just passing 'vm' instead, I chose to use what I had (at least for starters). After generating and testing code, I realized libDir wasn't created until after qemuBuildCommandLine returned successfully, so I moved the Write code to Launch (of course not even thinking I had the priv object, so pass it). Initially only the libDir was passed. I added the 2nd argument when I added the write "0" on Stop, which you question below and *KeyRemove. Since this pass, I see Pavel has made other changes to the libDir processing which means I could now do the Write in qemu_command.c and I won't have issues because libDir is NULL or the directory doesn't exist (a check I had at one time before writing - does libDir exist, if not then error). Sure - that's fine. I think a relic of my first thoughts on how this would work, but neglected when I finalized things - consider it gone... True - it was a coin flip - base64 encode it now or later just in the file. I can leave it un-encoded... I think I was also considering the save/restore XML logic for libvirtd restarts, but it seems I don't have to consider that any more. Fair enough - simplifies some things. It might mean checking the caps bit twice though. I guess I saw no harm in generating the secretKey (although I do now realize this is much too early). It is. Since I had allocation in *Alloc, I figured there needed to be something in *Free. It's one of those automatic reflexes. This was here before it became more apparent that the object lives for as long as the domain is defined. And masterKey is supposed as 32 bytes. Using "MASTER_KEY" wasn't meant to imply an sort of 32 or 64 bit "key" stored for an 'uint32' or 'uint64' (e.g. 'SIZE' vs. 'LEN' from my POV). There will eventually be an InitialzationVector which is 16 bytes. yeah right - I guess first pass I wasn't thinking in terms of how long the priv object lives. Pavel's changes make it a bit easier now too. When we free a key, we memset 0 on it to clear the heap. I guess I just figured writing a "0" to the file that's about to be deleted will (more or less) match that logic. You'll note the qemuDomainMasterKeyRemove also writes the "0". Thanks for the feedback - John

On 03/22/2016 10:08 AM, Daniel P. Berrange wrote: OK - well that simplifies certain things; however, I would think that means on libvirtd restart we would then have to read the master key file in order to repopulate the priv->masterKey, right? It didn't dawn on me when first going through this that the priv was only generated once at define time. But yeah, now that that realization is fresh in my mind, I certainly see the point. I guess I was initially thinking that the object was generated later, but I never revisited once it became more obvious that the private object was generated when the domain was defined. I will move it... OK - although it is used today in virsh/vsh and remote_driver... Ahhh.. I wasn't aware of that API in gnutls - I was searching on "other" strings using cscope. Thanks for the feedback - John

Add a capability bit for the qemu secret object Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- src/qemu/qemu_capabilities.c | 2 ++ src/qemu/qemu_capabilities.h | 1 + 2 files changed, 3 insertions(+) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index b223837..efbbad6 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -321,6 +321,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST, "qxl-vga.vram64_size_mb", /* 215 */ "chardev-logfile", "debug-threads", + "secret", ); @@ -1575,6 +1576,7 @@ struct virQEMUCapsStringFlags virQEMUCapsObjectTypes[] = { { "virtio-input-host-device", QEMU_CAPS_VIRTIO_INPUT_HOST }, { "virtio-input-host-pci", QEMU_CAPS_VIRTIO_INPUT_HOST }, { "mptsas1068", QEMU_CAPS_SCSI_MPTSAS1068 }, + { "secret", QEMU_CAPS_OBJECT_SECRET }, }; static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsVirtioBalloon[] = { diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h index caf3d1b..ae0d9b3 100644 --- a/src/qemu/qemu_capabilities.h +++ b/src/qemu/qemu_capabilities.h @@ -351,6 +351,7 @@ typedef enum { QEMU_CAPS_QXL_VGA_VRAM64, /* -device qxl-vga.vram64_size_mb */ QEMU_CAPS_CHARDEV_LOGFILE, /* -chardev logfile=xxxx */ QEMU_CAPS_NAME_DEBUG_THREADS, /* Is -name debug-threads= available */ + QEMU_CAPS_OBJECT_SECRET, /* -object secret */ QEMU_CAPS_LAST /* this must always be the last item */ } virQEMUCapsFlags; -- 2.5.0

On Mon, Mar 21, 2016 at 14:29:02 -0400, John Ferlan wrote: This doesn't seem to be terribly useful. Especially since you have to check for priv->masterKey anyways. Here is the correct place to generate the key. I don't really see the benefit of doing it even for qemu that does not support this feature. [...] You've added src/qemu/qemu_alias.c, so this belongs there. Peter