This is primarily designed to support an enlightened driver for the AMD SVSM based vTPM, but it could be used by any TPM driver which communicates with a TPM device implemented through the TCG TPM reference implementation (https://github.com/TrustedComputingGroup/TPM) Co-developed-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Co-developed-by: Claudio Carvalho <cclaudio@xxxxxxxxxxxxx> Signed-off-by: Claudio Carvalho <cclaudio@xxxxxxxxxxxxx> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> --- James, Claudio are you fine with the Cdb, Sob? The code is based to what was in the initial RFC, but I removed the tpm_platform module, moved some code in the header, changed some names, etc. For these reasons I reset the author but added C-o-b. Please, let me know if this is okay or if I need to do anything else (reset the author, etc.) --- include/linux/tpm_tcgsim.h | 136 +++++++++++++++++++++++++++++++++++++ 1 file changed, 136 insertions(+) create mode 100644 include/linux/tpm_tcgsim.h diff --git a/include/linux/tpm_tcgsim.h b/include/linux/tpm_tcgsim.h new file mode 100644 index 000000000000..bd5b123c393b --- /dev/null +++ b/include/linux/tpm_tcgsim.h @@ -0,0 +1,136 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2023 James.Bottomley@xxxxxxxxxxxxxxxxxxxxx + * Copyright (C) 2025 Red Hat, Inc. All Rights Reserved. + * + * Generic interface usable by TPM drivers interacting with devices + * implemented through the TCG Simulator. + */ +#ifndef _TPM_TCGSIM_H_ +#define _TPM_TCGSIM_H_ + +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/types.h> + +/* + * The current TCG Simulator TPM commands we support. The complete list is + * in the TcpTpmProtocol header: + * + * https://github.com/TrustedComputingGroup/TPM/blob/main/TPMCmd/Simulator/include/TpmTcpProtocol.h + */ + +#define TPM_SEND_COMMAND 8 +#define TPM_SIGNAL_CANCEL_ON 9 +#define TPM_SIGNAL_CANCEL_OFF 10 +/* + * Any platform specific commands should be placed here and should start + * at 0x8000 to avoid clashes with the TCG Simulator protocol. They should + * follow the same self describing buffer format below. + */ + +#define TPM_TCGSIM_MAX_BUFFER 4096 /* max req/resp buffer size */ + +/** + * struct tpm_req - generic request header for single word command + * + * @cmd: The command to send + */ +struct tpm_req { + u32 cmd; +} __packed; + +/** + * struct tpm_resp - generic response header + * + * @size: The response size (zero if nothing follows) + * + * Note: most TCG Simulator commands simply return zero here with no indication + * of success or failure. + */ +struct tpm_resp { + u32 size; +} __packed; + +/** + * struct tpm_send_cmd_req - Structure for a TPM_SEND_COMMAND request + * + * @hdr: The request header whit the command (must be TPM_SEND_COMMAND) + * @locality: The locality + * @inbuf_size: The size of the input buffer following + * @inbuf: A buffer of size inbuf_size + * + * Note that TCG Simulator expects @inbuf_size to be equal to the size of the + * specific TPM command, otherwise an TPM_RC_COMMAND_SIZE error is + * returned. + */ +struct tpm_send_cmd_req { + struct tpm_req hdr; + u8 locality; + u32 inbuf_size; + u8 inbuf[]; +} __packed; + +/** + * struct tpm_send_cmd_req - Structure for a TPM_SEND_COMMAND response + * + * @hdr: The response header whit the following size + * @outbuf: A buffer of size hdr.size + */ +struct tpm_send_cmd_resp { + struct tpm_resp hdr; + u8 outbuf[]; +} __packed; + +/** + * tpm_tcgsim_fill_send_cmd() - fill a struct tpm_send_cmd_req to be sent to the + * TCG Simulator. + * @req: The struct tpm_send_cmd_req to fill + * @locality: The locality + * @buf: The buffer from where to copy the payload of the command + * @len: The size of the buffer + * + * Return: 0 on success, negative error code on failure. + */ +static inline int +tpm_tcgsim_fill_send_cmd(struct tpm_send_cmd_req *req, u8 locality, + const u8 *buf, size_t len) +{ + if (len > TPM_TCGSIM_MAX_BUFFER - sizeof(*req)) + return -EINVAL; + + req->hdr.cmd = TPM_SEND_COMMAND; + req->locality = locality; + req->inbuf_size = len; + + memcpy(req->inbuf, buf, len); + + return 0; +} + +/** + * tpm_tcgsim_parse_send_cmd() - Parse a struct tpm_send_cmd_resp received from + * the TCG Simulator + * @resp: The struct tpm_send_cmd_resp to parse + * @buf: The buffer where to copy the response + * @len: The size of the buffer + * + * Return: buffer size filled with the response on success, negative error + * code on failure. + */ +static inline int +tpm_tcgsim_parse_send_cmd(const struct tpm_send_cmd_resp *resp, u8 *buf, + size_t len) +{ + if (len < resp->hdr.size) + return -E2BIG; + + if (resp->hdr.size > TPM_TCGSIM_MAX_BUFFER - sizeof(*resp)) + return -EINVAL; // Invalid response from the platform TPM + + memcpy(buf, resp->outbuf, resp->hdr.size); + + return resp->hdr.size; +} + +#endif /* _TPM_TCGSIM_H_ */ -- 2.48.1
