[libvirt] [PATCH v6 15/19] tpm: Use fd to pass password to swtpm_setup and swtpm
Stefan Berger
stefanb at linux.vnet.ibm.com
Thu Jul 25 14:30:29 UTC 2019
Allow vTPM state encryption when swtpm_setup and swtpm support
passing a passphrase using a file descriptor.
This patch enables the encryption of the vTPM state only. It does
not encrypt the state during migration, so the destination secret
does not need to have the same password at this point.
Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>
Reviewed-by: Daniel P. Berrangé <berrange at redhat.com>
---
src/libvirt_private.syms | 2 +
src/qemu/qemu_tpm.c | 110 ++++++++++++++++++++++++++++++++++++++-
src/util/virtpm.c | 16 ++++++
src/util/virtpm.h | 3 ++
4 files changed, 129 insertions(+), 2 deletions(-)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index e6249caa80..a8d65e4318 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -3182,7 +3182,9 @@ virTPMEmulatorInit;
virTPMGetSwtpm;
virTPMGetSwtpmIoctl;
virTPMGetSwtpmSetup;
+virTPMSwtpmCapsGet;
virTPMSwtpmFeatureTypeFromString;
+virTPMSwtpmSetupCapsGet;
virTPMSwtpmSetupFeatureTypeFromString;
diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c
index 9f1e7e20ba..27a31efe50 100644
--- a/src/qemu/qemu_tpm.c
+++ b/src/qemu/qemu_tpm.c
@@ -43,6 +43,7 @@
#include "dirname.h"
#include "qemu_tpm.h"
#include "virtpm.h"
+#include "secret_util.h"
#define VIR_FROM_THIS VIR_FROM_NONE
@@ -373,6 +374,66 @@ qemuTPMEmulatorPrepareHost(virDomainTPMDefPtr tpm,
return ret;
}
+/*
+ * qemuTPMSetupEncryption
+ *
+ * @secretuuid: The UUID with the secret holding passphrase
+ * @cmd: the virCommand to transfer the secret to
+ *
+ * Returns file descriptor representing the read-end of a pipe.
+ * The passphrase can be read from this pipe. Returns < 0 in case
+ * of error.
+ *
+ * This function reads the passphrase and writes it into the
+ * write-end of a pipe so that the read-end of the pipe can be
+ * passed to the emulator for reading the passphrase from.
+ */
+static int
+qemuTPMSetupEncryption(const unsigned char *secretuuid,
+ virCommandPtr cmd)
+{
+ int ret = -1;
+ int pipefd[2] = { -1, -1 };
+ virConnectPtr conn;
+ VIR_AUTOFREE(uint8_t *) secret = NULL;
+ size_t secret_len;
+ virSecretLookupTypeDef seclookupdef = {
+ .type = VIR_SECRET_LOOKUP_TYPE_UUID,
+ };
+
+ conn = virGetConnectSecret();
+ if (!conn)
+ return -1;
+
+ memcpy(seclookupdef.u.uuid, secretuuid, sizeof(seclookupdef.u.uuid));
+ if (virSecretGetSecretString(conn, &seclookupdef,
+ VIR_SECRET_USAGE_TYPE_VTPM,
+ &secret, &secret_len) < 0)
+ goto error;
+
+ if (pipe(pipefd) == -1) {
+ virReportSystemError(errno, "%s",
+ _("Unable to create pipe"));
+ goto error;
+ }
+
+ if (virCommandSetSendBuffer(cmd, pipefd[1], secret, secret_len) < 0)
+ goto error;
+
+ secret = NULL;
+ ret = pipefd[0];
+
+ cleanup:
+ virObjectUnref(conn);
+
+ return ret;
+
+ error:
+ VIR_FORCE_CLOSE(pipefd[1]);
+ VIR_FORCE_CLOSE(pipefd[0]);
+
+ goto cleanup;
+}
/*
* qemuTPMEmulatorRunSetup
@@ -387,6 +448,7 @@ qemuTPMEmulatorPrepareHost(virDomainTPMDefPtr tpm,
* @logfile: The file to write the log into; it must be writable
* for the user given by userid or 'tss'
* @tpmversion: The version of the TPM, either a TPM 1.2 or TPM 2
+ * @encryption: pointer to virStorageEncryption holding secret
*
* Setup the external swtpm by creating endorsement key and
* certificates for it.
@@ -399,7 +461,8 @@ qemuTPMEmulatorRunSetup(const char *storagepath,
uid_t swtpm_user,
gid_t swtpm_group,
const char *logfile,
- const virDomainTPMVersion tpmversion)
+ const virDomainTPMVersion tpmversion,
+ const unsigned char *secretuuid)
{
virCommandPtr cmd = NULL;
int exitstatus;
@@ -407,6 +470,7 @@ qemuTPMEmulatorRunSetup(const char *storagepath,
char uuid[VIR_UUID_STRING_BUFLEN];
char *vmid = NULL;
VIR_AUTOFREE(char *)swtpm_setup = virTPMGetSwtpmSetup();
+ VIR_AUTOCLOSE pwdfile_fd = -1;
if (!swtpm_setup)
return -1;
@@ -439,6 +503,23 @@ qemuTPMEmulatorRunSetup(const char *storagepath,
break;
}
+ if (secretuuid) {
+ if (!virTPMSwtpmSetupCapsGet(
+ VIR_TPM_SWTPM_SETUP_FEATURE_CMDARG_PWDFILE_FD)) {
+ virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED,
+ _("%s does not support passing a passphrase using a file "
+ "descriptor"), virTPMGetSwtpmSetup());
+ goto cleanup;
+ }
+ if ((pwdfile_fd = qemuTPMSetupEncryption(secretuuid, cmd)) < 0)
+ goto cleanup;
+
+ virCommandAddArg(cmd, "--pwdfile-fd");
+ virCommandAddArgFormat(cmd, "%d", pwdfile_fd);
+ virCommandAddArgList(cmd, "--cipher", "aes-256-cbc", NULL);
+ virCommandPassFD(cmd, pwdfile_fd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+ pwdfile_fd = -1;
+ }
virCommandAddArgList(cmd,
"--tpm-state", storagepath,
@@ -502,6 +583,8 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDefPtr tpm,
bool created = false;
char *pidfile;
VIR_AUTOFREE(char *) swtpm = virTPMGetSwtpm();
+ VIR_AUTOCLOSE pwdfile_fd = -1;
+ const unsigned char *secretuuid = NULL;
if (!swtpm)
return NULL;
@@ -510,10 +593,14 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDefPtr tpm,
&created, swtpm_user, swtpm_group) < 0)
return NULL;
+ if (tpm->data.emulator.hassecretuuid)
+ secretuuid = tpm->data.emulator.secretuuid;
+
if (created &&
qemuTPMEmulatorRunSetup(tpm->data.emulator.storagepath, vmname, vmuuid,
privileged, swtpm_user, swtpm_group,
- tpm->data.emulator.logfile, tpm->version) < 0)
+ tpm->data.emulator.logfile, tpm->version,
+ secretuuid) < 0)
goto error;
unlink(tpm->data.emulator.source.data.nix.path);
@@ -556,6 +643,25 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDefPtr tpm,
virCommandAddArgFormat(cmd, "file=%s", pidfile);
VIR_FREE(pidfile);
+ if (tpm->data.emulator.hassecretuuid) {
+ if (!virTPMSwtpmCapsGet(VIR_TPM_SWTPM_FEATURE_CMDARG_PWD_FD)) {
+ virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED,
+ _("%s does not support passing passphrase via file descriptor"),
+ virTPMGetSwtpm());
+ goto error;
+ }
+
+ pwdfile_fd = qemuTPMSetupEncryption(tpm->data.emulator.secretuuid, cmd);
+ if (pwdfile_fd)
+ goto error;
+
+ virCommandAddArg(cmd, "--key");
+ virCommandAddArgFormat(cmd, "pwdfd=%d,mode=aes-256-cbc",
+ pwdfile_fd);
+ virCommandPassFD(cmd, pwdfile_fd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+ pwdfile_fd = -1;
+ }
+
return cmd;
error:
diff --git a/src/util/virtpm.c b/src/util/virtpm.c
index 99abbf3f8b..52094d911e 100644
--- a/src/util/virtpm.c
+++ b/src/util/virtpm.c
@@ -352,3 +352,19 @@ virTPMEmulatorInit(void)
return ret;
}
+
+bool
+virTPMSwtpmCapsGet(unsigned int cap)
+{
+ if (virTPMEmulatorInit() < 0)
+ return false;
+ return virBitmapIsBitSet(swtpm_caps, cap);
+}
+
+bool
+virTPMSwtpmSetupCapsGet(unsigned int cap)
+{
+ if (virTPMEmulatorInit() < 0)
+ return false;
+ return virBitmapIsBitSet(swtpm_setup_caps, cap);
+}
diff --git a/src/util/virtpm.h b/src/util/virtpm.h
index 157b43ff17..50948aac9a 100644
--- a/src/util/virtpm.h
+++ b/src/util/virtpm.h
@@ -27,6 +27,9 @@ char *virTPMGetSwtpmSetup(void);
char *virTPMGetSwtpmIoctl(void);
int virTPMEmulatorInit(void);
+bool virTPMSwtpmCapsGet(unsigned int cap);
+bool virTPMSwtpmSetupCapsGet(unsigned int cap);
+
typedef enum {
VIR_TPM_SWTPM_FEATURE_CMDARG_PWD_FD,
--
2.20.1
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