Re: [libvirt] [PATCH v7 15/19] tpm: Use fd to pass password to swtpm_setup and swtpm

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(a)linux.ibm.com&gt; Reviewed-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- 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(-)

/* * 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: