Re: [libvirt] [PATCH 14/18] 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; --- src/libvirt_private.syms | 2 + src/qemu/qemu_tpm.c | 101 ++++++++++++++++++++++++++++++++++++++- src/tpm/virtpm.c | 16 +++++++ src/tpm/virtpm.h | 3 ++ 4 files changed, 120 insertions(+), 2 deletions(-) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index d2045895a1..d693f7facb 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1456,6 +1456,8 @@ virTPMEmulatorInit; virTPMGetSwtpm; virTPMGetSwtpmIoctl; virTPMGetSwtpmSetup; +virTPMSwtpmCapsGet; +virTPMSwtpmSetupCapsGet; # util/viralloc.h diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c index 2afa8db448..6e7d38b7e0 100644 --- a/src/qemu/qemu_tpm.c +++ b/src/qemu/qemu_tpm.c @@ -43,6 +43,8 @@ #include "dirname.h" #include "qemu_tpm.h" #include "virtpm.h" +#include "secret_util.h" +#include "virtpm_conf.h" #define VIR_FROM_THIS VIR_FROM_NONE @@ -372,6 +374,60 @@ qemuTPMEmulatorPrepareHost(virDomainTPMDefPtr tpm, return ret; } +/* + * qemuTPMSetupEncryption + * + * @encryption: pointer to virStorageEncryption holding secret + * + * 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(virStorageEncryptionPtr encryption) +{ + int ret = -1; + int pipefd[2] = { -1, -1 }; + virConnectPtr conn; + uint8_t *secret = NULL; + size_t secret_len; + + conn = virGetConnectSecret(); + if (!conn) + return -1; + + if (virSecretGetSecretString(conn, &encryption->secrets[0]->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 (safewrite(pipefd[1], secret, secret_len) != secret_len) + goto error;

+ + ret = pipefd[0]; + + cleanup: + VIR_FREE(secret); + VIR_FORCE_CLOSE(pipefd[1]); + virObjectUnref(conn); + + return ret; + + error: + VIR_FORCE_CLOSE(pipefd[0]); + + goto cleanup; +} /* * qemuTPMEmulatorRunSetup @@ -386,6 +442,7 @@ 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. @@ -398,13 +455,15 @@ qemuTPMEmulatorRunSetup(const char *storagepath, uid_t swtpm_user, gid_t swtpm_group, const char *logfile, - const virDomainTPMVersion tpmversion) + const virDomainTPMVersion tpmversion, + virStorageEncryptionPtr encryption) { virCommandPtr cmd = NULL; int exitstatus; int ret = -1; char uuid[VIR_UUID_STRING_BUFLEN]; char *vmid = NULL; + int pwdfile_fd = -1; if (!privileged && tpmversion == VIR_DOMAIN_TPM_VERSION_1_2) return virFileWriteStr(logfile, @@ -434,6 +493,22 @@ qemuTPMEmulatorRunSetup(const char *storagepath, break; } + if (encryption) { + 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(encryption)) < 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); + } virCommandAddArgList(cmd, "--tpm-state", storagepath, @@ -461,6 +536,7 @@ qemuTPMEmulatorRunSetup(const char *storagepath, cleanup: VIR_FREE(vmid); virCommandFree(cmd); + VIR_FORCE_CLOSE(pwdfile_fd);

return ret; } @@ -496,6 +572,7 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDefPtr tpm, virCommandPtr cmd = NULL; bool created = false; char *pidfile; + int pwdfile_fd = -1; if (qemuTPMCreateEmulatorStorage(tpm->data.emulator.storagepath, &created, swtpm_user, swtpm_group) < 0) @@ -504,7 +581,8 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDefPtr tpm, 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, + tpm->data.emulator.encryption) < 0) goto error; unlink(tpm->data.emulator.source.data.nix.path); @@ -547,11 +625,30 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDefPtr tpm, virCommandAddArgFormat(cmd, "file=%s", pidfile); VIR_FREE(pidfile); + if (tpm->data.emulator.encryption) { + 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.encryption); + if (pwdfile_fd < 0) + goto error; + + virCommandAddArg(cmd, "--key"); + virCommandAddArgFormat(cmd, "pwdfd=%d,mode=aes-256-cbc,kdf=pbkdf2", + pwdfile_fd); + virCommandPassFD(cmd, pwdfile_fd, VIR_COMMAND_PASS_FD_CLOSE_PARENT); + } + return cmd; error: if (created) qemuTPMDeleteEmulatorStorage(tpm); + VIR_FORCE_CLOSE(pwdfile_fd);

virCommandFree(cmd); diff --git a/src/tpm/virtpm.c b/src/tpm/virtpm.c index 42dd2b1bb2..7e95dbad6f 100644 --- a/src/tpm/virtpm.c +++ b/src/tpm/virtpm.c @@ -312,3 +312,19 @@ virTPMEmulatorInit(void) return 0; } + +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/tpm/virtpm.h b/src/tpm/virtpm.h index 66d55fb231..a8bb6e1ba0 100644 --- a/src/tpm/virtpm.h +++ b/src/tpm/virtpm.h @@ -26,3 +26,6 @@ const char *virTPMGetSwtpm(void); const char *virTPMGetSwtpmSetup(void); const char *virTPMGetSwtpmIoctl(void); int virTPMEmulatorInit(void); + +bool virTPMSwtpmCapsGet(unsigned int cap); +bool virTPMSwtpmSetupCapsGet(unsigned int cap); -- 2.20.1