1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2017 Google
4  *
5  * Authors:
6  *      Thiebaud Weksteen <tweek@google.com>
7  */
8 
9 #include <linux/efi.h>
10 #include <linux/tpm_eventlog.h>
11 
12 #include "../tpm.h"
13 #include "common.h"
14 
15 /* read binary bios log from EFI configuration table */
tpm_read_log_efi(struct tpm_chip * chip)16 int tpm_read_log_efi(struct tpm_chip *chip)
17 {
18 
19 	struct efi_tcg2_final_events_table *final_tbl = NULL;
20 	int final_events_log_size = efi_tpm_final_log_size;
21 	struct linux_efi_tpm_eventlog *log_tbl;
22 	struct tpm_bios_log *log;
23 	u32 log_size;
24 	u8 tpm_log_version;
25 	void *tmp;
26 	int ret;
27 
28 	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
29 		return -ENODEV;
30 
31 	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
32 		return -ENODEV;
33 
34 	log = &chip->log;
35 
36 	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl), MEMREMAP_WB);
37 	if (!log_tbl) {
38 		pr_err("Could not map UEFI TPM log table !\n");
39 		return -ENOMEM;
40 	}
41 
42 	log_size = log_tbl->size;
43 	memunmap(log_tbl);
44 
45 	if (!log_size) {
46 		pr_warn("UEFI TPM log area empty\n");
47 		return -EIO;
48 	}
49 
50 	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl) + log_size,
51 			   MEMREMAP_WB);
52 	if (!log_tbl) {
53 		pr_err("Could not map UEFI TPM log table payload!\n");
54 		return -ENOMEM;
55 	}
56 
57 	/* malloc EventLog space */
58 	log->bios_event_log = kmemdup(log_tbl->log, log_size, GFP_KERNEL);
59 	if (!log->bios_event_log) {
60 		ret = -ENOMEM;
61 		goto out;
62 	}
63 
64 	log->bios_event_log_end = log->bios_event_log + log_size;
65 	tpm_log_version = log_tbl->version;
66 
67 	ret = tpm_log_version;
68 
69 	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR ||
70 	    final_events_log_size == 0 ||
71 	    tpm_log_version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
72 		goto out;
73 
74 	final_tbl = memremap(efi.tpm_final_log,
75 			     sizeof(*final_tbl) + final_events_log_size,
76 			     MEMREMAP_WB);
77 	if (!final_tbl) {
78 		pr_err("Could not map UEFI TPM final log\n");
79 		kfree(log->bios_event_log);
80 		ret = -ENOMEM;
81 		goto out;
82 	}
83 
84 	/*
85 	 * The 'final events log' size excludes the 'final events preboot log'
86 	 * at its beginning.
87 	 */
88 	final_events_log_size -= log_tbl->final_events_preboot_size;
89 
90 	/*
91 	 * Allocate memory for the 'combined log' where we will append the
92 	 * 'final events log' to.
93 	 */
94 	tmp = krealloc(log->bios_event_log,
95 		       log_size + final_events_log_size,
96 		       GFP_KERNEL);
97 	if (!tmp) {
98 		kfree(log->bios_event_log);
99 		ret = -ENOMEM;
100 		goto out;
101 	}
102 
103 	log->bios_event_log = tmp;
104 
105 	/*
106 	 * Append any of the 'final events log' that didn't also end up in the
107 	 * 'main log'. Events can be logged in both if events are generated
108 	 * between GetEventLog() and ExitBootServices().
109 	 */
110 	memcpy((void *)log->bios_event_log + log_size,
111 	       final_tbl->events + log_tbl->final_events_preboot_size,
112 	       final_events_log_size);
113 	/*
114 	 * The size of the 'combined log' is the size of the 'main log' plus
115 	 * the size of the 'final events log'.
116 	 */
117 	log->bios_event_log_end = log->bios_event_log +
118 		log_size + final_events_log_size;
119 
120 out:
121 	memunmap(final_tbl);
122 	memunmap(log_tbl);
123 	return ret;
124 }
125