Re: [PATCH] tpm-emulator: add a TPM emulator pass through

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Sun, Jan 08, 2017 at 04:58:33PM -0800, James Bottomley wrote:
> 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/egYHeGw8Jk@public.gmane.org>

I use tpm_vtpm_proxy and [1] to do this.

[1] http://git.infradead.org/users/jjs/tpm2-scripts.git/blob_plain/HEAD:/tpm2-simulator-vtpm

/JArkko


> ---
>  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
> 
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index 277186d..034faa2 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -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
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index 251d0ed..e2de69d 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -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
> diff --git a/drivers/char/tpm/tpm-emulator.c b/drivers/char/tpm/tpm-emulator.c
> new file mode 100644
> index 0000000..f78008c
> --- /dev/null
> +++ b/drivers/char/tpm/tpm-emulator.c
> @@ -0,0 +1,231 @@
> +/*
> + * Copyright 2017 James.Bottomley-d9PhHud1JfjCXq6kfMZ53/egYHeGw8Jk@public.gmane.org
> + *
> + * 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/egYHeGw8Jk@public.gmane.org>");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.6.6
> 
> 
> 
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