1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*
* TPM handling.
*
* Copyright (C) 2016 CoreOS, Inc
* Copyright (C) 2017 Google, Inc.
* Matthew Garrett <mjg59@google.com>
* Thiebaud Weksteen <tweek@google.com>
*
* This file is part of the Linux kernel, and is made available under the
* terms of the GNU General Public License version 2.
*/
#include <linux/efi.h>
#include <linux/tpm_eventlog.h>
#include <asm/efi.h>
#include "efistub.h"
#ifdef CONFIG_RESET_ATTACK_MITIGATION
static const efi_char16_t efi_MemoryOverWriteRequest_name[] =
L"MemoryOverwriteRequestControl";
#define MEMORY_ONLY_RESET_CONTROL_GUID \
EFI_GUID(0xe20939be, 0x32d4, 0x41be, 0xa1, 0x50, 0x89, 0x7f, 0x85, 0xd4, 0x98, 0x29)
#define get_efi_var(name, vendor, ...) \
efi_call_runtime(get_variable, \
(efi_char16_t *)(name), (efi_guid_t *)(vendor), \
__VA_ARGS__)
#define set_efi_var(name, vendor, ...) \
efi_call_runtime(set_variable, \
(efi_char16_t *)(name), (efi_guid_t *)(vendor), \
__VA_ARGS__)
/*
* Enable reboot attack mitigation. This requests that the firmware clear the
* RAM on next reboot before proceeding with boot, ensuring that any secrets
* are cleared. If userland has ensured that all secrets have been removed
* from RAM before reboot it can simply reset this variable.
*/
void efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
{
u8 val = 1;
efi_guid_t var_guid = MEMORY_ONLY_RESET_CONTROL_GUID;
efi_status_t status;
unsigned long datasize = 0;
status = get_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
NULL, &datasize, NULL);
if (status == EFI_NOT_FOUND)
return;
set_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
EFI_VARIABLE_NON_VOLATILE |
EFI_VARIABLE_BOOTSERVICE_ACCESS |
EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);
}
#endif
static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
{
efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
efi_status_t status;
efi_physical_addr_t log_location, log_last_entry;
struct linux_efi_tpm_eventlog *log_tbl = NULL;
unsigned long first_entry_addr, last_entry_addr;
size_t log_size, last_entry_size;
efi_bool_t truncated;
void *tcg2_protocol = NULL;
status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
&tcg2_protocol);
if (status != EFI_SUCCESS)
return;
status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
&log_location, &log_last_entry, &truncated);
if (status != EFI_SUCCESS)
return;
if (!log_location)
return;
first_entry_addr = (unsigned long) log_location;
/*
* We populate the EFI table even if the logs are empty.
*/
if (!log_last_entry) {
log_size = 0;
} else {
last_entry_addr = (unsigned long) log_last_entry;
/*
* get_event_log only returns the address of the last entry.
* We need to calculate its size to deduce the full size of
* the logs.
*/
last_entry_size = sizeof(struct tcpa_event) +
((struct tcpa_event *) last_entry_addr)->event_size;
log_size = log_last_entry - log_location + last_entry_size;
}
/* Allocate space for the logs and copy them. */
status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
sizeof(*log_tbl) + log_size,
(void **) &log_tbl);
if (status != EFI_SUCCESS) {
efi_printk(sys_table_arg,
"Unable to allocate memory for event log\n");
return;
}
memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
log_tbl->size = log_size;
log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
status = efi_call_early(install_configuration_table,
&linux_eventlog_guid, log_tbl);
if (status != EFI_SUCCESS)
goto err_free;
return;
err_free:
efi_call_early(free_pool, log_tbl);
}
void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
{
/* Only try to retrieve the logs in 1.2 format. */
efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
}
|
