1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2023 Beckhoff Automation GmbH & Co. KG
5  * Author: Corvin Köhne <corvink@FreeBSD.org>
6  */
7 
8 #include <sys/types.h>
9 
10 #include <err.h>
11 #include <errno.h>
12 #include <fcntl.h>
13 #include <malloc_np.h>
14 #include <stdlib.h>
15 #include <unistd.h>
16 
17 #include "config.h"
18 #include "tpm_device.h"
19 #include "tpm_emul.h"
20 
21 struct tpm_passthru {
22 	int fd;
23 };
24 
25 struct tpm_resp_hdr {
26 	uint16_t tag;
27 	uint32_t len;
28 	uint32_t errcode;
29 } __packed;
30 
31 static int
32 tpm_passthru_init(void **sc, nvlist_t *nvl)
33 {
34 	struct tpm_passthru *tpm;
35 	const char *path;
36 
37 	tpm = calloc(1, sizeof(struct tpm_passthru));
38 	if (tpm == NULL) {
39 		warnx("%s: failed to allocate tpm passthru", __func__);
40 		return (ENOMEM);
41 	}
42 
43 	path = get_config_value_node(nvl, "path");
44 	tpm->fd = open(path, O_RDWR);
45 	if (tpm->fd < 0) {
46 		warnx("%s: unable to open tpm device \"%s\"", __func__, path);
47 		return (ENOENT);
48 	}
49 
50 	*sc = tpm;
51 
52 	return (0);
53 }
54 
55 static int
56 tpm_passthru_execute_cmd(void *sc, void *cmd, uint32_t cmd_size, void *rsp,
57     uint32_t rsp_size)
58 {
59 	struct tpm_passthru *tpm;
60 	ssize_t len;
61 
62 	if (rsp_size < (ssize_t)sizeof(struct tpm_resp_hdr)) {
63 		warn("%s: rsp_size of %u is too small", __func__, rsp_size);
64 		return (EINVAL);
65 	}
66 
67 	tpm = sc;
68 
69 	len = write(tpm->fd, cmd, cmd_size);
70 	if (len != cmd_size) {
71 		warn("%s: cmd write failed (bytes written: %zd / %d)", __func__,
72 		    len, cmd_size);
73 		return (EFAULT);
74 	}
75 
76 	len = read(tpm->fd, rsp, rsp_size);
77 	if (len < (ssize_t)sizeof(struct tpm_resp_hdr)) {
78 		warn("%s: rsp read failed (bytes read: %zd / %d)", __func__,
79 		    len, rsp_size);
80 		return (EFAULT);
81 	}
82 
83 	return (0);
84 }
85 
86 static void
87 tpm_passthru_deinit(void *sc)
88 {
89 	struct tpm_passthru *tpm;
90 
91 	tpm = sc;
92 	if (tpm == NULL)
93 		return;
94 
95 	if (tpm->fd >= 0)
96 		close(tpm->fd);
97 
98 	free(tpm);
99 }
100 
101 static const struct tpm_emul tpm_emul_passthru = {
102 	.name = "passthru",
103 	.init = tpm_passthru_init,
104 	.deinit = tpm_passthru_deinit,
105 	.execute_cmd = tpm_passthru_execute_cmd,
106 };
107 TPM_EMUL_SET(tpm_emul_passthru);
108