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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * TPM handling.
4 *
5 * Copyright (C) 2016 CoreOS, Inc
6 * Copyright (C) 2017 Google, Inc.
7 * Matthew Garrett <mjg59@google.com>
8 * Thiebaud Weksteen <tweek@google.com>
9 */
10#include <linux/efi.h>
11#include <linux/tpm_eventlog.h>
12#include <asm/efi.h>
13
14#include "efistub.h"
15
16#ifdef CONFIG_RESET_ATTACK_MITIGATION
17static const efi_char16_t efi_MemoryOverWriteRequest_name[] =
18 L"MemoryOverwriteRequestControl";
19
20#define MEMORY_ONLY_RESET_CONTROL_GUID \
21 EFI_GUID(0xe20939be, 0x32d4, 0x41be, 0xa1, 0x50, 0x89, 0x7f, 0x85, 0xd4, 0x98, 0x29)
22
23/*
24 * Enable reboot attack mitigation. This requests that the firmware clear the
25 * RAM on next reboot before proceeding with boot, ensuring that any secrets
26 * are cleared. If userland has ensured that all secrets have been removed
27 * from RAM before reboot it can simply reset this variable.
28 */
29void efi_enable_reset_attack_mitigation(void)
30{
31 u8 val = 1;
32 efi_guid_t var_guid = MEMORY_ONLY_RESET_CONTROL_GUID;
33 efi_status_t status;
34 unsigned long datasize = 0;
35
36 status = get_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
37 NULL, &datasize, NULL);
38
39 if (status == EFI_NOT_FOUND)
40 return;
41
42 set_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
43 EFI_VARIABLE_NON_VOLATILE |
44 EFI_VARIABLE_BOOTSERVICE_ACCESS |
45 EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);
46}
47
48#endif
49
50void efi_retrieve_tpm2_eventlog(void)
51{
52 efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
53 efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
54 efi_status_t status;
55 efi_physical_addr_t log_location = 0, log_last_entry = 0;
56 struct linux_efi_tpm_eventlog *log_tbl = NULL;
57 struct efi_tcg2_final_events_table *final_events_table = NULL;
58 unsigned long first_entry_addr, last_entry_addr;
59 size_t log_size, last_entry_size;
60 efi_bool_t truncated;
61 int version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
62 efi_tcg2_protocol_t *tcg2_protocol = NULL;
63 int final_events_size = 0;
64
65 status = efi_bs_call(locate_protocol, &tcg2_guid, NULL,
66 (void **)&tcg2_protocol);
67 if (status != EFI_SUCCESS)
68 return;
69
70 status = efi_call_proto(tcg2_protocol, get_event_log, version,
71 &log_location, &log_last_entry, &truncated);
72
73 if (status != EFI_SUCCESS || !log_location) {
74 version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
75 status = efi_call_proto(tcg2_protocol, get_event_log, version,
76 &log_location, &log_last_entry,
77 &truncated);
78 if (status != EFI_SUCCESS || !log_location)
79 return;
80
81 }
82
83 first_entry_addr = (unsigned long) log_location;
84
85 /*
86 * We populate the EFI table even if the logs are empty.
87 */
88 if (!log_last_entry) {
89 log_size = 0;
90 } else {
91 last_entry_addr = (unsigned long) log_last_entry;
92 /*
93 * get_event_log only returns the address of the last entry.
94 * We need to calculate its size to deduce the full size of
95 * the logs.
96 */
97 if (version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
98 /*
99 * The TCG2 log format has variable length entries,
100 * and the information to decode the hash algorithms
101 * back into a size is contained in the first entry -
102 * pass a pointer to the final entry (to calculate its
103 * size) and the first entry (so we know how long each
104 * digest is)
105 */
106 last_entry_size =
107 __calc_tpm2_event_size((void *)last_entry_addr,
108 (void *)(long)log_location,
109 false);
110 } else {
111 last_entry_size = sizeof(struct tcpa_event) +
112 ((struct tcpa_event *) last_entry_addr)->event_size;
113 }
114 log_size = log_last_entry - log_location + last_entry_size;
115 }
116
117 /* Allocate space for the logs and copy them. */
118 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
119 sizeof(*log_tbl) + log_size, (void **)&log_tbl);
120
121 if (status != EFI_SUCCESS) {
122 efi_err("Unable to allocate memory for event log\n");
123 return;
124 }
125
126 /*
127 * Figure out whether any events have already been logged to the
128 * final events structure, and if so how much space they take up
129 */
130 if (version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
131 final_events_table = get_efi_config_table(LINUX_EFI_TPM_FINAL_LOG_GUID);
132 if (final_events_table && final_events_table->nr_events) {
133 struct tcg_pcr_event2_head *header;
134 int offset;
135 void *data;
136 int event_size;
137 int i = final_events_table->nr_events;
138
139 data = (void *)final_events_table;
140 offset = sizeof(final_events_table->version) +
141 sizeof(final_events_table->nr_events);
142
143 while (i > 0) {
144 header = data + offset + final_events_size;
145 event_size = __calc_tpm2_event_size(header,
146 (void *)(long)log_location,
147 false);
148 final_events_size += event_size;
149 i--;
150 }
151 }
152
153 memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
154 log_tbl->size = log_size;
155 log_tbl->final_events_preboot_size = final_events_size;
156 log_tbl->version = version;
157 memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
158
159 status = efi_bs_call(install_configuration_table,
160 &linux_eventlog_guid, log_tbl);
161 if (status != EFI_SUCCESS)
162 goto err_free;
163 return;
164
165err_free:
166 efi_bs_call(free_pool, log_tbl);
167}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * TPM handling.
4 *
5 * Copyright (C) 2016 CoreOS, Inc
6 * Copyright (C) 2017 Google, Inc.
7 * Matthew Garrett <mjg59@google.com>
8 * Thiebaud Weksteen <tweek@google.com>
9 */
10#include <linux/efi.h>
11#include <linux/tpm_eventlog.h>
12#include <asm/efi.h>
13
14#include "efistub.h"
15
16#ifdef CONFIG_RESET_ATTACK_MITIGATION
17static const efi_char16_t efi_MemoryOverWriteRequest_name[] =
18 L"MemoryOverwriteRequestControl";
19
20#define MEMORY_ONLY_RESET_CONTROL_GUID \
21 EFI_GUID(0xe20939be, 0x32d4, 0x41be, 0xa1, 0x50, 0x89, 0x7f, 0x85, 0xd4, 0x98, 0x29)
22
23/*
24 * Enable reboot attack mitigation. This requests that the firmware clear the
25 * RAM on next reboot before proceeding with boot, ensuring that any secrets
26 * are cleared. If userland has ensured that all secrets have been removed
27 * from RAM before reboot it can simply reset this variable.
28 */
29void efi_enable_reset_attack_mitigation(void)
30{
31 u8 val = 1;
32 efi_guid_t var_guid = MEMORY_ONLY_RESET_CONTROL_GUID;
33 efi_status_t status;
34 unsigned long datasize = 0;
35
36 status = get_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
37 NULL, &datasize, NULL);
38
39 if (status == EFI_NOT_FOUND)
40 return;
41
42 set_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
43 EFI_VARIABLE_NON_VOLATILE |
44 EFI_VARIABLE_BOOTSERVICE_ACCESS |
45 EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);
46}
47
48#endif
49
50void efi_retrieve_tpm2_eventlog(void)
51{
52 efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
53 efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
54 efi_status_t status;
55 efi_physical_addr_t log_location = 0, log_last_entry = 0;
56 struct linux_efi_tpm_eventlog *log_tbl = NULL;
57 struct efi_tcg2_final_events_table *final_events_table = NULL;
58 unsigned long first_entry_addr, last_entry_addr;
59 size_t log_size, last_entry_size;
60 efi_bool_t truncated;
61 int version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
62 efi_tcg2_protocol_t *tcg2_protocol = NULL;
63 int final_events_size = 0;
64
65 status = efi_bs_call(locate_protocol, &tcg2_guid, NULL,
66 (void **)&tcg2_protocol);
67 if (status != EFI_SUCCESS)
68 return;
69
70 status = efi_call_proto(tcg2_protocol, get_event_log, version,
71 &log_location, &log_last_entry, &truncated);
72
73 if (status != EFI_SUCCESS || !log_location) {
74 version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
75 status = efi_call_proto(tcg2_protocol, get_event_log, version,
76 &log_location, &log_last_entry,
77 &truncated);
78 if (status != EFI_SUCCESS || !log_location)
79 return;
80
81 }
82
83 first_entry_addr = (unsigned long) log_location;
84
85 /*
86 * We populate the EFI table even if the logs are empty.
87 */
88 if (!log_last_entry) {
89 log_size = 0;
90 } else {
91 last_entry_addr = (unsigned long) log_last_entry;
92 /*
93 * get_event_log only returns the address of the last entry.
94 * We need to calculate its size to deduce the full size of
95 * the logs.
96 */
97 if (version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
98 /*
99 * The TCG2 log format has variable length entries,
100 * and the information to decode the hash algorithms
101 * back into a size is contained in the first entry -
102 * pass a pointer to the final entry (to calculate its
103 * size) and the first entry (so we know how long each
104 * digest is)
105 */
106 last_entry_size =
107 __calc_tpm2_event_size((void *)last_entry_addr,
108 (void *)(long)log_location,
109 false);
110 } else {
111 last_entry_size = sizeof(struct tcpa_event) +
112 ((struct tcpa_event *) last_entry_addr)->event_size;
113 }
114 log_size = log_last_entry - log_location + last_entry_size;
115 }
116
117 /* Allocate space for the logs and copy them. */
118 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
119 sizeof(*log_tbl) + log_size, (void **)&log_tbl);
120
121 if (status != EFI_SUCCESS) {
122 efi_err("Unable to allocate memory for event log\n");
123 return;
124 }
125
126 /*
127 * Figure out whether any events have already been logged to the
128 * final events structure, and if so how much space they take up
129 */
130 if (version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
131 final_events_table = get_efi_config_table(LINUX_EFI_TPM_FINAL_LOG_GUID);
132 if (final_events_table && final_events_table->nr_events) {
133 struct tcg_pcr_event2_head *header;
134 int offset;
135 void *data;
136 int event_size;
137 int i = final_events_table->nr_events;
138
139 data = (void *)final_events_table;
140 offset = sizeof(final_events_table->version) +
141 sizeof(final_events_table->nr_events);
142
143 while (i > 0) {
144 header = data + offset + final_events_size;
145 event_size = __calc_tpm2_event_size(header,
146 (void *)(long)log_location,
147 false);
148 final_events_size += event_size;
149 i--;
150 }
151 }
152
153 memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
154 log_tbl->size = log_size;
155 log_tbl->final_events_preboot_size = final_events_size;
156 log_tbl->version = version;
157 memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
158
159 status = efi_bs_call(install_configuration_table,
160 &linux_eventlog_guid, log_tbl);
161 if (status != EFI_SUCCESS)
162 goto err_free;
163 return;
164
165err_free:
166 efi_bs_call(free_pool, log_tbl);
167}