tpm-emulator: add a TPM emulator pass through

I noticed, while playing around with the kernel based resource manager, that it's very advantageous to have an emulated TPM device to test now that I'm playing with startup sequences and TPM ownership.

This is an emulator pass through. It connects an existing emulator running on the platform (expected to be the MS Simulator available from https://sourceforge.net/projects/ibmswtpm2/) and adds it as an in-kernel device, meaning you can exercise the kernel TPM interface from either inside the kernel or using the device node.

The tpm-emulator simply connects to the command socket of the MS simulator (on localhost:2321) and proxies TPM commands. The destination and port are settable as module parameters meaning that the TPM emulator doesn't have to be running locally.

Quoted 11 lines · James Bottomley

I noticed, while playing around with the kernel based resource manager, that it's very advantageous to have an emulated TPM device to
test now that I'm playing with startup sequences and TPM ownership.

This is an emulator pass through. It connects an existing emulator running on the platform (expected to be the MS Simulator available from https://sourceforge.net/projects/ibmswtpm2/) and adds it as an in-kernel device, meaning you can exercise the kernel TPM interface from either inside the kernel or using the device node.

Quoted 4 lines

The tpm-emulator simply connects to the command socket of the MS simulator (on localhost:2321) and proxies TPM commands. The destination and port are settable as module parameters meaning that the TPM emulator doesn't have to be running locally.

What is wrong with using drivers/char/tpm/tpm_vtpm_proxy.c and doing the socket connection in userspace?

Quoted 17 lines · Jason Gunthorpe

Quoted 15 lines · James Bottomley

I noticed, while playing around with the kernel based resource manager, that it's very advantageous to have an emulated TPM device to
test now that I'm playing with startup sequences and TPM ownership.

This is an emulator pass through. It connects an existing emulator running on the platform (expected to be the MS Simulator available from https://sourceforge.net/projects/ibmswtpm2/) and adds it as an in-kernel device, meaning you can exercise the kernel TPM interface from either inside the kernel or using the device node.

The tpm-emulator simply connects to the command socket of the MS simulator (on localhost:2321) and proxies TPM commands. The destination and port are settable as module parameters meaning that the TPM emulator doesn't have to be running locally.

Quoted 2 lines

What is wrong with using drivers/char/tpm/tpm_vtpm_proxy.c and doing the socket connection in userspace?

Simplicity, mostly. It's a tiny driver to proxy the network protocol directly, meaning it's much easier to set up.

Plus if you're running smoke tests in a VM you can actually run the emulator in the host without any additional code in the guest.

Quoted 20 lines · James Bottomley

Quoted 19 lines · Jason Gunthorpe

Quoted 17 lines · James Bottomley

I noticed, while playing around with the kernel based resource manager, that it's very advantageous to have an emulated TPM device to test now that I'm playing with startup sequences and TPM ownership.

This is an emulator pass through. It connects an existing emulator running on the platform (expected to be the MS Simulator available from
https://sourceforge.net/projects/ibmswtpm2/) and adds it as an in-kernel device, meaning you can exercise the kernel TPM interface from either inside the kernel or using the device node.

The tpm-emulator simply connects to the command socket of the MS simulator (on localhost:2321) and proxies TPM commands. The destination and port are settable as module parameters meaning that the TPM emulator doesn't have to be running locally.

Quoted 5 lines

Quoted 2 lines

What is wrong with using drivers/char/tpm/tpm_vtpm_proxy.c and doing the socket connection in userspace?

Simplicity, mostly. It's a tiny driver to proxy the network protocol directly, meaning it's much easier to set up.

Not sure I see it, surely running a program in userspace is simpler than patching the kernel?

Quoted 2 lines

Plus if you're running smoke tests in a VM you can actually run the emulator in the host without any additional code in the guest.

I haven't tried it, but qemu has TPM passthrough support, so it should be able to pass /dev/tpm1, created by vtpm through to the guest. AFAIK this should support all existing guests without a custom kernel or messing with module options.

Honestly, I'd rather see the emulator community get behind vtpm..

Quoted 2 lines

Not sure I see it, surely running a program in userspace is simpler than patching the kernel?

Heh, is that a serious question to a kernel developer? If the program actually existed, sure, but does it?

Quoted 4 lines

Quoted 2 lines

Not sure I see it, surely running a program in userspace is simpler than patching the kernel?

Heh, is that a serious question to a kernel developer? If the program actually existed, sure, but does it?

Stefan has something to connect vtpm to a TPM2 emulator.

Examples:

./src/vtpmctrl --tpm2 \
   --spawn /bin/swtpm chardev --tpm2 --fd %fd --tpmstate dir=/tmp

Quoted 3 lines · Stefan Berger

Examples:

./src/vtpmctrl --tpm2 \
    --spawn /bin/swtpm chardev --tpm2 --fd %fd --tpmstate dir=/tmp

git head for swtpm is giving

Created TPM device /dev/tpm1; vTPM device has fd 4, major/minor = 247/1.
chardev: unrecognized option '--tpm2'

Quoted 10 lines · James Bottomley

Quoted 4 lines · Stefan Berger

Examples:

./src/vtpmctrl --tpm2 \
    --spawn /bin/swtpm chardev --tpm2 --fd %fd --tpmstate

dir=/tmp

git head for swtpm is giving

Created TPM device /dev/tpm1; vTPM device has fd 4, major/minor = 247/1.
chardev: unrecognized option '--tpm2'

You need the tpm2-preview branches of libtpms and swtpm. Why you need them is related to the format in which the persistent data are written by the TPM 2 implementation. For QEMU it should probably big endian, but so far it's not.

Here's a short wiki of libtpms pointing out the issues.

https://github.com/stefanberger/libtpms/wiki

https://github.com/stefanberger/libtpms/tree/tpm2-previewa.rev138
https://github.com/stefanberger/swtpm/tree/tpm2-preview

Quoted 18 lines · Stefan Berger

Quoted 10 lines · James Bottomley

Quoted 4 lines · Stefan Berger

Examples:

./src/vtpmctrl --tpm2 \
     --spawn /bin/swtpm chardev --tpm2 --fd %fd --tpmstate

dir=/tmp

git head for swtpm is giving

Created TPM device /dev/tpm1; vTPM device has fd 4, major/minor = 247/1.
chardev: unrecognized option '--tpm2'

You need the tpm2-preview branches of libtpms and swtpm. Why you need them is related to the format in which the persistent data are written by the TPM 2 implementation. For QEMU it should probably big endian, but so far it's not.

Here's a short wiki of libtpms pointing out the issues.

Quoted 4 lines

https://github.com/stefanberger/libtpms/wiki

https://github.com/stefanberger/libtpms/tree/tpm2-previewa.rev138
https://github.com/stefanberger/swtpm/tree/tpm2-preview

Basically the synopsis is that it's not yet working well enough to run the resource manager smoke tests and I need to continue using the ibmswtpm2 as the emulator or run against the real thing for the time being.

Quoted 24 lines · James Bottomley

Quoted 23 lines · Stefan Berger

Quoted 11 lines · James Bottomley

Quoted 4 lines · Stefan Berger

Examples:

./src/vtpmctrl --tpm2 \
     --spawn /bin/swtpm chardev --tpm2 --fd %fd --tpmstate

dir=/tmp

git head for swtpm is giving

Created TPM device /dev/tpm1; vTPM device has fd 4, major/minor =
247/1.
chardev: unrecognized option '--tpm2'

You need the tpm2-preview branches of libtpms and swtpm. Why you need
them is related to the format in which the persistent data are written by the TPM 2 implementation. For QEMU it should probably big
endian, but so far it's not.

Here's a short wiki of libtpms pointing out the issues.

https://github.com/stefanberger/libtpms/wiki

Quoted 6 lines

Quoted 2 lines

https://github.com/stefanberger/libtpms/tree/tpm2-previewa.rev138
https://github.com/stefanberger/swtpm/tree/tpm2-preview

Basically the synopsis is that it's not yet working well enough to run the resource manager smoke tests and I need to continue using the ibmswtpm2 as the emulator or run against the real thing for the time being.

Have you tried it ?

Quoted 25 lines · Stefan Berger

Quoted 24 lines · James Bottomley

Quoted 23 lines · Stefan Berger

Quoted 11 lines · James Bottomley

Quoted 4 lines · Stefan Berger

Examples:

./src/vtpmctrl --tpm2 \
      --spawn /bin/swtpm chardev --tpm2 --fd %fd --tpmstate

dir=/tmp

git head for swtpm is giving

Created TPM device /dev/tpm1; vTPM device has fd 4, major/minor =
247/1.
chardev: unrecognized option '--tpm2'

You need the tpm2-preview branches of libtpms and swtpm. Why you need
them is related to the format in which the persistent data are written by the TPM 2 implementation. For QEMU it should probably big
endian, but so far it's not.

Here's a short wiki of libtpms pointing out the issues.

https://github.com/stefanberger/libtpms/wiki

Quoted 7 lines

Quoted 6 lines

Quoted 2 lines

https://github.com/stefanberger/libtpms/tree/tpm2-previewa.rev138
https://github.com/stefanberger/swtpm/tree/tpm2-preview

Basically the synopsis is that it's not yet working well enough to run the resource manager smoke tests and I need to continue using the ibmswtpm2 as the emulator or run against the real thing for the time being.

Have you tried it ?

Git head of the tpm2-preview branch of libtpms isn't building for me:

tpm2/ExecCommand.c: In function 'ExecuteCommand':
tpm2/ExecCommand.c:434:37: error: 'commandIndex' may be used uninitialized in this function [-Werror=maybe-uninitialized]

      buffer = MemoryGetResponseBuffer(commandIndex);
                                      ^

cc1: all warnings being treated as errors

I also think you probably need this patch

James

---

configure.ac +0 -0

index e84bc0f..4ab149d 100644

Quoted 57 lines · James Bottomley

Quoted 25 lines · Stefan Berger

Quoted 24 lines · James Bottomley

Quoted 23 lines · Stefan Berger

Quoted 6 lines · James Bottomley

Quoted 5 lines · Stefan Berger

Examples:

./src/vtpmctrl --tpm2 \
      --spawn /bin/swtpm chardev --tpm2 --fd %fd -

-tpmstate
dir=/tmp

Quoted 7 lines

git head for swtpm is giving

Created TPM device /dev/tpm1; vTPM device has fd 4, major/minor
=
247/1.
chardev: unrecognized option '--tpm2'

You need the tpm2-preview branches of libtpms and swtpm. Why you need them is related to the format in which the persistent data are written by the TPM 2 implementation. For QEMU it should probably big endian, but so far it's not.

Here's a short wiki of libtpms pointing out the issues.

https://github.com/stefanberger/libtpms/wiki

Quoted 8 lines

Quoted 7 lines

Quoted 3 lines

https://github.com/stefanberger/libtpms/tree/tpm2-previewa.re
v138
https://github.com/stefanberger/swtpm/tree/tpm2-preview

Basically the synopsis is that it's not yet working well enough to run the resource manager smoke tests and I need to continue using the ibmswtpm2 as the emulator or run against the real thing for the time being.

Have you tried it ?

Git head of the tpm2-preview branch of libtpms isn't building for me:

tpm2/ExecCommand.c: In function 'ExecuteCommand':
tpm2/ExecCommand.c:434:37: error: 'commandIndex' may be used uninitialized in this function [-Werror=maybe-uninitialized]

      buffer = MemoryGetResponseBuffer(commandIndex);
                                      ^

cc1: all warnings being treated as errors

I also think you probably need this patch

James

---

configure.ac +0 -0

index e84bc0f..4ab149d 100644
@@ -125,7 +125,7 @@ openssl)
  esac
 

Quoted 7 lines

configure.ac +1 -1

  AC_ARG_WITH([tpm2],
-	AC_HELP_STRING([--wih-tpm2],
+	AC_HELP_STRING([--with-tpm2],
                         [build libtpms with TPM2 support
 (experimental)]),
          AC_MSG_RESULT([Building with TPM2 support])

          #if test "x$cryptolib" = "xfreebl"; then

Thanks. I fixed this now to make it at least compilable. The more recent branch is the tpm2-preview.rev138, which makes that other branch more or less obsolete.

Quoted 5 lines

Thanks. I fixed this now to make it at least compilable. The more recent branch is the tpm2-preview.rev138, which makes that other branch more or less obsolete.

OK, with this branch, I can get a mostly successful run of the smoke tests. The failure looks to be a dispute over who handles TPM_RC_RETRY

Quoted 8 lines · James Bottomley

Quoted 5 lines

Thanks. I fixed this now to make it at least compilable. The more recent branch is the tpm2-preview.rev138, which makes that other branch more or less obsolete.

OK, with this branch, I can get a mostly successful run of the smoke tests. The failure looks to be a dispute over who handles TPM_RC_RETRY

The following now also works after a (forced) updated on the swtpm TPM2 preview branch:

swtpm chardev --vtpm-proxy --tpmstate dir=/tmp --tpm2 swtpm chardev --vtpm-proxy --tpmstate dir=/tmp

Quoted 8 lines · Stefan Berger

Quoted 7 lines · James Bottomley

Quoted 4 lines

Thanks. I fixed this now to make it at least compilable. The more recent branch is the tpm2-preview.rev138, which makes that other branch more or less obsolete.

OK, with this branch, I can get a mostly successful run of the smoke tests. The failure looks to be a dispute over who handles TPM_RC_RETRY

Quoted 5 lines

The following now also works after a (forced) updated on the swtpm TPM2 preview branch:

swtpm chardev --vtpm-proxy --tpmstate dir=/tmp --tpm2 swtpm chardev --vtpm-proxy --tpmstate dir=/tmp

What would it take to get this into the master branch and released, so those of us who use standard distribution tools can get it?

Quoted 16 lines · James Bottomley

Quoted 15 lines · Stefan Berger

Quoted 10 lines · James Bottomley

Quoted 6 lines

Thanks. I fixed this now to make it at least compilable. The more
recent branch is the tpm2-preview.rev138, which makes that other
branch more or less obsolete.

OK, with this branch, I can get a mostly successful run of the smoke tests. The failure looks to be a dispute over who handles
TPM_RC_RETRY

The following now also works after a (forced) updated on the swtpm
TPM2 preview branch:

Quoted 5 lines

Quoted 2 lines

swtpm chardev --vtpm-proxy --tpmstate dir=/tmp --tpm2 swtpm chardev --vtpm-proxy --tpmstate dir=/tmp

What would it take to get this into the master branch and released, so
those of us who use standard distribution tools can get it?

The problem lies in the code that writes the TPM 2 state in host format
rather than in Big Endian format, which would make the state portable and likely that is the preferred format for QEMU integration. Besides that there is some functionality missing for suspending the volatile state of the TPM 2.

https://github.com/stefanberger/libtpms/wiki

I didn't really see a need to use an emulated TPM in the kernel until Jarkko's smoke tests caused a DA lockout on my physical TPM at which point not impacting all my other TPM based stuff while playing with the kernel suddenly seemed important.

I noticed, while playing around with the kernel based resource manager, that it's very advantageous to have an emulated TPM device to test now that I'm playing with startup sequences and TPM ownership.

This is an emulator pass through. It connects an existing emulator running on the platform (expected to be the MS Simulator available from https://sourceforge.net/projects/ibmswtpm2/) and adds it as an in-kernel device, meaning you can exercise the kernel TPM interface from either inside the kernel or using the device node.

The tpm-emulator simply connects to the command socket of the MS simulator (on localhost:2321) and proxies TPM commands. The destination and port are settable as module parameters meaning that the TPM emulator doesn't have to be running locally.

Signed-off-by James Bottomley <James.Bottomley-d9PhHud1JfjCXq6kfMZ53/[email protected]>

---
 drivers/char/tpm/Kconfig        |   7 ++
 drivers/char/tpm/Makefile       |   1 +
 drivers/char/tpm/tpm-emulator.c | 231 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 239 insertions(+)
 create mode 100644 drivers/char/tpm/tpm-emulator.c

drivers/char/tpm/Kconfig +7 -0

index 277186d..034faa2 100644
@@ -151,6 +151,13 @@ config TCG_VTPM_PROXY
 	  /dev/vtpmX and a server-side file descriptor on which the vTPM
 	  can receive commands.
 
+config TCG_EMULATOR
+	tristate "TPM Emulator Interface"
+	depends on m && TCG_TPM
+	---help---
+	  This creates a kernel TPM device which expects to connect to
+	  the MS simulator socket.  You must have the simulator running
+	  (powered on and started) before inserting the device.
 
 source "drivers/char/tpm/st33zp24/Kconfig"
 endif # TCG_TPM

drivers/char/tpm/Makefile +1 -0

index 251d0ed..e2de69d 100644
@@ -20,3 +20,4 @@ obj-$(CONFIG_TCG_TIS_ST33ZP24) += st33zp24/
 obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
 obj-$(CONFIG_TCG_CRB) += tpm_crb.o
 obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o
+obj-$(CONFIG_TCG_EMULATOR) += tpm-emulator.o

drivers/char/tpm/tpm-emulator.c new file +231 -0

new file mode 100644
index 0000000..f78008c
@@ -0,0 +1,231 @@
+/*
+ * Copyright 2017 James.Bottomley-d9PhHud1JfjCXq6kfMZ53/[email protected]
+ *
+ * GPLv2
+ *
+ * Simple socket based connector to a userspace TPM emulator
+ */
+
+#include <linux/kernel.h>
+#include <linux/net.h>
+#include <linux/inet.h>
+#include <linux/in.h>
+#include <linux/module.h>
+
+#include <net/net_namespace.h>
+
+#include "tpm.h"
+
+/*
+ * Currently we only support the MSSIM TPM connections, so every
+ * command must be prefixed with MSSIM_CMD and we have to send
+ * MSSIM_END before we close the socket
+ */
+#define MSSIM_CMD	8
+#define MSSIM_END	20
+
+/*
+ * Initial assumptions: by default connect to the microsoft simulator
+ * command port on localhost.  Note: this emulator makes no use of the
+ * platform port, so the emulator must be properly initialised (power
+ * on and startup) before being used by this in-kernel system
+ */
+static char *server = "127.0.0.1";
+module_param_named(server, server, charp, 0400);
+MODULE_PARM_DESC(server, "TPM Emulator server address.");
+static int port = 2321;
+module_param_named(port, port, uint, 0400);
+MODULE_PARM_DESC(port, "TPM Emulator server port.");
+
+static struct device tdev;
+
+static struct socket *tsock;
+struct sockaddr_in tin;
+
+static int priv_recvmsg(void *buf, size_t len, int flags)
+{
+	struct kvec iov = {
+		.iov_base = buf,
+		.iov_len = len,
+	};
+	struct msghdr msg = {
+		.msg_flags = (flags ? flags : MSG_WAITALL | MSG_NOSIGNAL)
+	};
+	return kernel_recvmsg(tsock, &msg, &iov, 1, len, msg.msg_flags);
+}
+
+static void priv_shutdown(void)
+{
+	kernel_sock_shutdown(tsock, SHUT_RDWR);
+	sock_release(tsock);
+	tsock = NULL;
+}
+
+static int priv_send(void *buf, size_t len)
+{
+	int err;
+	int sent = 0;
+
+	struct kvec iov = {
+		.iov_base = buf,
+		.iov_len = len,
+	};
+	struct msghdr msg = {
+		.msg_name = NULL,
+		.msg_namelen = 0,
+		.msg_control = NULL,
+		.msg_controllen = 0,
+		.msg_flags = MSG_WAITALL | MSG_NOSIGNAL,
+	};
+
+	do {
+		err = kernel_sendmsg(tsock, &msg, &iov, 1, iov.iov_len);
+		if (err == -EAGAIN)
+			continue;
+		if (err < 0) {
+			priv_shutdown();
+			return err;
+		}
+		sent += err;
+		iov.iov_base += err;
+		iov.iov_len -= err;
+	} while (sent < len);
+
+	return 0;
+}
+
+static int emu_send(struct tpm_chip *chip, u8 *buf, size_t len)
+{
+	int ret;
+	u32 cmd = htonl(MSSIM_CMD), netlen = htonl(len);
+	u8 locality = 0;
+
+	ret = sock_create_kern(&init_net, PF_INET, SOCK_STREAM, IPPROTO_TCP,
+			       &tsock);
+	if (ret)
+		return ret;
+
+	ret = kernel_connect(tsock, (struct sockaddr *)&tin, sizeof(tin), 0);
+	if (ret)
+		goto out;
+
+	ret = priv_send(&cmd, sizeof(cmd));
+	if (ret)
+		goto out;
+	ret = priv_send(&locality, sizeof(locality));
+	if (ret)
+		goto out;
+	ret = priv_send(&netlen, sizeof(netlen));
+	if (ret)
+		goto out;
+
+	ret = priv_send(buf, len);
+
+ out:
+	if (ret < 0)
+		priv_shutdown();
+	return ret;
+
+}
+
+static int emu_recv(struct tpm_chip *chip, u8 *buf, size_t len)
+{
+	int ret;
+	u32 header = htonl(MSSIM_END);
+	u32 reclen;
+	u32 ack;
+
+	ret = priv_recvmsg(&reclen, sizeof(reclen), 0);
+	if (ret != sizeof(reclen)) {
+		dev_err(&tdev, "Socket receive failed: %d\n", ret);
+		goto out;
+	}
+	reclen = ntohl(reclen);
+	if (len < reclen) {
+		dev_err(&tdev, "response is too large %d\n", reclen);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = priv_recvmsg(buf, reclen, 0);
+	if (ret > 0)
+		/* receive the ack packet, should be zero */
+		priv_recvmsg(&ack, sizeof(ack), 0);
+
+ out:
+	priv_send(&header, sizeof(header));
+	priv_shutdown();
+
+	return ret;
+}
+
+static struct tpm_class_ops emulator_ops = {
+	.flags = TPM_OPS_AUTO_STARTUP,
+	.send = emu_send,
+	.recv = emu_recv,
+};
+
+static void emu_dev_release(struct device *dev)
+{
+}
+
+static int emu_init(void)
+{
+	int err;
+	struct tpm_chip *chip;
+
+	tin.sin_family = AF_INET;
+	tin.sin_addr.s_addr = in_aton(server);
+	tin.sin_port = htons(port);
+
+	device_initialize(&tdev);
+	/* stop drivers/base/core.c from complaining */
+	tdev.release = emu_dev_release;
+	err = dev_set_name(&tdev, "emulated-tpm");
+	if (err)
+		goto err_out;
+	err = device_add(&tdev);
+	if (err)
+		goto err_out;
+
+	chip = tpmm_chip_alloc(&tdev, &emulator_ops);
+	if (IS_ERR(chip)) {
+		err = PTR_ERR(chip);
+		goto err_del;
+	}
+	chip->flags |= TPM_CHIP_FLAG_IRQ;
+	err = tpm2_probe(chip);
+	if (err)
+		goto err_del;
+
+	err = tpm_chip_register(chip);
+
+	dev_info(&tdev, "%s TPM emulator\n",
+		 (chip->flags & TPM_CHIP_FLAG_TPM2) ? "2.0" : "1.2");
+
+	if (!err)
+		return 0;
+
+ err_del:
+	device_del(&tdev);
+ err_out:
+
+	put_device(&tdev);
+
+	return err;
+}
+
+static void emu_exit(void)
+{
+	struct tpm_chip *chip = dev_get_drvdata(&tdev);
+
+	tpm_chip_unregister(chip);
+	device_del(&tdev);
+	put_device(&tdev);
+}
+
+module_init(emu_init);
+module_exit(emu_exit);
+
+MODULE_AUTHOR("James Bottomley <James.Bottomley-d9PhHud1JfjCXq6kfMZ53/[email protected]>");
+MODULE_LICENSE("GPL v2");

Signature · 11 lines

2.6.6



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