[PATCH v2] qemu: tpm: Run swtpm_setup --create-config-files in session mode

[Daniel P. Berrangé]

On Fri, Oct 08, 2021 at 09:56:35AM -0400, Stefan Berger wrote:
> Using swtpm v0.7.0 we can run swtpm_setup to create default config files
> for swtpm_setup and swtpm-localca in session mode. Now a user can start
> a VM with an attached TPM without having to run this program on the
> command line before. This program needs to run once.

Fedora 34 only has v0.6.0 and so....

> 
> This patch addresses the issue raised in
> https://bugzilla.redhat.com/show_bug.cgi?id=2010649
> 
> Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>
> 
> v2:
>   - fixed return code if swtpm_setup doesn't support the option
> ---
>  src/qemu/qemu_tpm.c | 43 +++++++++++++++++++++++++++++++++++++++++++
>  src/util/virtpm.c   |  1 +
>  src/util/virtpm.h   |  1 +
>  3 files changed, 45 insertions(+)
> 
> diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c
> index 100481503c..bf6c8e5ad5 100644
> --- a/src/qemu/qemu_tpm.c
> +++ b/src/qemu/qemu_tpm.c
> @@ -385,6 +385,46 @@ qemuTPMSetupEncryption(const unsigned char *secretuuid,
>      return virCommandSetSendBuffer(cmd, g_steal_pointer(&secret), secret_len);
>  }
>  
> +
> +/*
> + * qemuTPMCreateConfigFiles: run swtpm_setup --create-config-files skip-if-exist
> + *
> + * @logfile: The file to write the log into; it must be writable
> + *           for the user given by userid or 'tss'
> + */
> +static int
> +qemuTPMCreateConfigFiles(const char *logfile)
> +{
> +    g_autofree char *swtpm_setup = virTPMGetSwtpmSetup();
> +    g_autoptr(virCommand) cmd = NULL;
> +    int exitstatus;
> +
> +    if (!swtpm_setup)
> +        return -1;
> +
> +    if (!virTPMSwtpmSetupCapsGet(
> +            VIR_TPM_SWTPM_SETUP_FEATURE_CMDARG_CREATE_CONFIG_FILES))
> +        return 0;
> +
> +    cmd = virCommandNew(swtpm_setup);
> +    if (!cmd)
> +        return -1;
> +
> +    virCommandAddArgList(cmd, "--create-config-files", "skip-if-exist", NULL);
> +    virCommandClearCaps(cmd);
> +
> +    if (virCommandRun(cmd, &exitstatus) < 0 || exitstatus != 0) {
> +        virReportError(VIR_ERR_INTERNAL_ERROR,
> +                       _("Could not run '%s' to create config files. exitstatus: %d; "
> +                         "Check error log '%s' for details."),
> +                          swtpm_setup, exitstatus, logfile);

This error path will trigger preventing use of the TPM, even if
the user has manually setup the config themselves.

Why aren't you running /usr/share/swtpm/swtpm-create-user-config-files
instead which is what I see does exist on Fedora today.

RHEL-8 has even older swtpm than Fedora.

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|