Enable the passing of a file descriptor via fd=<..> to access the host's
TPM device using the TPM passthrough driver.
Signed-off-by: Stefan Berger <stef...@linux.vnet.ibm.com>
---
hw/tpm_passthrough.c | 61 ++++++++++++++++++++++++++++++++++++++-----------
qemu-config.c | 5 ++++
qemu-options.hx | 11 ++++++--
3 files changed, 60 insertions(+), 17 deletions(-)
diff --git a/hw/tpm_passthrough.c b/hw/tpm_passthrough.c
index dee7418..fa3c99b 100644
--- a/hw/tpm_passthrough.c
+++ b/hw/tpm_passthrough.c
@@ -322,30 +322,62 @@ static int tpm_passthrough_handle_device_opts(QemuOpts
*opts, TPMBackend *tb)
{
const char *value;
size_t bufsize;
+ struct stat statbuf;
- value = qemu_opt_get(opts, "path");
- if (!value) {
- value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
- }
+ value = qemu_opt_get(opts, "fd");
+ if (value) {
+ if (qemu_opt_get(opts, "path")) {
+ error_report("fd= is invalid with path=");
+ goto err_exit;
+ }
+
+ tb->s.tpm_pt->tpm_fd = qemu_parse_fd(value);
+ if (tb->s.tpm_pt->tpm_fd < 0) {
+ error_report("Illegal file descriptor for TPM device.\n");
+ goto err_exit;
+ }
+
+ bufsize = sizeof("fd=") + sizeof(stringify(INT_MAX)) + 1;
+
+ tb->parameters = g_malloc0(bufsize);
+
+ snprintf(tb->parameters, bufsize, "fd=%d", tb->s.tpm_pt->tpm_fd);
+ } else {
+ value = qemu_opt_get(opts, "path");
+ if (!value) {
+ value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
+ }
+
+ tb->s.tpm_pt->tpm_dev = g_strdup(value);
- tb->s.tpm_pt->tpm_dev = g_strdup(value);
+ bufsize = sizeof("path=") + strlen(tb->s.tpm_pt->tpm_dev) + 1;
- bufsize = sizeof("path=") + strlen(tb->s.tpm_pt->tpm_dev) + 1;
+ tb->parameters = g_malloc0(bufsize);
- tb->parameters = g_malloc0(bufsize);
+ snprintf(tb->parameters, bufsize, "path=%s", tb->s.tpm_pt->tpm_dev);
- snprintf(tb->parameters, bufsize, "path=%s", tb->s.tpm_pt->tpm_dev);
+ tb->s.tpm_pt->tpm_fd = open(tb->s.tpm_pt->tpm_dev, O_RDWR);
+ if (tb->s.tpm_pt->tpm_fd < 0) {
+ error_report("Cannot access TPM device using '%s'.\n",
+ tb->s.tpm_pt->tpm_dev);
+ goto err_free_parameters;
+ }
+ }
+
+ if (fstat(tb->s.tpm_pt->tpm_fd, &statbuf) != 0) {
+ error_report("Cannot determine file descriptor type for TPM "
+ "device: %s", strerror(errno));
+ goto err_close_tpmdev;
+ }
- tb->s.tpm_pt->tpm_fd = open(tb->s.tpm_pt->tpm_dev, O_RDWR);
- if (tb->s.tpm_pt->tpm_fd < 0) {
- error_report("Cannot access TPM device using '%s'.\n",
- tb->s.tpm_pt->tpm_dev);
+ /* only allow character devices for now */
+ if (!S_ISCHR(statbuf.st_mode)) {
+ error_report("TPM file descriptor is not a character device");
goto err_free_parameters;
}
if (tpm_passthrough_test_tpmdev(tb->s.tpm_pt->tpm_fd)) {
- error_report("'%s' is not a TPM device.\n",
- tb->s.tpm_pt->tpm_dev);
+ error_report("Device is not a TPM.\n");
goto err_close_tpmdev;
}
@@ -362,6 +394,7 @@ static int tpm_passthrough_handle_device_opts(QemuOpts
*opts, TPMBackend *tb)
g_free(tb->s.tpm_pt->tpm_dev);
tb->s.tpm_pt->tpm_dev = NULL;
+ err_exit:
return 1;
}
diff --git a/qemu-config.c b/qemu-config.c
index edc8d5d..a5e2677 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -628,6 +628,11 @@ static QemuOptsList qemu_tpmdev_opts = {
.type = QEMU_OPT_STRING,
.help = "Persistent storage for TPM state",
},
+ {
+ .name = "fd",
+ .type = QEMU_OPT_STRING,
+ .help = "Filedescriptor for accessing the TPM",
+ },
{ /* end of list */ }
},
};
diff --git a/qemu-options.hx b/qemu-options.hx
index c8fbe07..4b262fb 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2007,8 +2007,9 @@ DEFHEADING(TPM device options:)
DEF("tpmdev", HAS_ARG, QEMU_OPTION_tpmdev, \
"-tpmdev [passthrough],id=id[,option][,option][,...]\n"
- "-tpmdev passthrough,id=id[,path=path]\n"
- " use path to provide path to a character device; default
is /dev/tpm0\n",
+ "-tpmdev passthrough,id=id[,path=path][,fd=h]\n"
+ " use path to provide path to a character device; default
is /dev/tpm0\n"
+ " use fd to provide a file descriptor to a character
device\n",
QEMU_ARCH_ALL)
STEXI
@@ -2030,7 +2031,7 @@ Use ? to print all available TPM backend types.
qemu -tpmdev ?
@end example
-@item -tpmdev passthrough, id=@var{id}, path=@var{path}
+@item -tpmdev passthrough, id=@var{id}, path=@var{path}, fd=@var{h}
(Linux-host only) Enable access to the host's TPM using the passthrough
driver.
@@ -2039,6 +2040,10 @@ driver.
a Linux host this would be @code{/dev/tpm0}.
@option{path} is optional and by default @code{/dev/tpm0} is used.
+@option{fd} specifies the file descriptor of the host's TPM device.
+@option{fd} and @option{path} are mutually exclusive.
+@option{fd} is optional.
+
Some notes about using the host's TPM with the passthrough driver:
The TPM device accessed by the passthrough driver must not be
--
1.7.4.4
