Merge branch 'x86-topology-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[muen/linux.git] / drivers / firmware / efi / libstub / tpm.c
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
17 static 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 #define get_efi_var(name, vendor, ...) \
24         efi_call_runtime(get_variable, \
25                          (efi_char16_t *)(name), (efi_guid_t *)(vendor), \
26                          __VA_ARGS__)
27
28 #define set_efi_var(name, vendor, ...) \
29         efi_call_runtime(set_variable, \
30                          (efi_char16_t *)(name), (efi_guid_t *)(vendor), \
31                          __VA_ARGS__)
32
33 /*
34  * Enable reboot attack mitigation. This requests that the firmware clear the
35  * RAM on next reboot before proceeding with boot, ensuring that any secrets
36  * are cleared. If userland has ensured that all secrets have been removed
37  * from RAM before reboot it can simply reset this variable.
38  */
39 void efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
40 {
41         u8 val = 1;
42         efi_guid_t var_guid = MEMORY_ONLY_RESET_CONTROL_GUID;
43         efi_status_t status;
44         unsigned long datasize = 0;
45
46         status = get_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
47                              NULL, &datasize, NULL);
48
49         if (status == EFI_NOT_FOUND)
50                 return;
51
52         set_efi_var(efi_MemoryOverWriteRequest_name, &var_guid,
53                     EFI_VARIABLE_NON_VOLATILE |
54                     EFI_VARIABLE_BOOTSERVICE_ACCESS |
55                     EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);
56 }
57
58 #endif
59
60 static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
61 {
62         efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
63         efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
64         efi_status_t status;
65         efi_physical_addr_t log_location = 0, log_last_entry = 0;
66         struct linux_efi_tpm_eventlog *log_tbl = NULL;
67         unsigned long first_entry_addr, last_entry_addr;
68         size_t log_size, last_entry_size;
69         efi_bool_t truncated;
70         void *tcg2_protocol = NULL;
71
72         status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
73                                 &tcg2_protocol);
74         if (status != EFI_SUCCESS)
75                 return;
76
77         status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
78                                 EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
79                                 &log_location, &log_last_entry, &truncated);
80         if (status != EFI_SUCCESS)
81                 return;
82
83         if (!log_location)
84                 return;
85         first_entry_addr = (unsigned long) log_location;
86
87         /*
88          * We populate the EFI table even if the logs are empty.
89          */
90         if (!log_last_entry) {
91                 log_size = 0;
92         } else {
93                 last_entry_addr = (unsigned long) log_last_entry;
94                 /*
95                  * get_event_log only returns the address of the last entry.
96                  * We need to calculate its size to deduce the full size of
97                  * the logs.
98                  */
99                 last_entry_size = sizeof(struct tcpa_event) +
100                         ((struct tcpa_event *) last_entry_addr)->event_size;
101                 log_size = log_last_entry - log_location + last_entry_size;
102         }
103
104         /* Allocate space for the logs and copy them. */
105         status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
106                                 sizeof(*log_tbl) + log_size,
107                                 (void **) &log_tbl);
108
109         if (status != EFI_SUCCESS) {
110                 efi_printk(sys_table_arg,
111                            "Unable to allocate memory for event log\n");
112                 return;
113         }
114
115         memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
116         log_tbl->size = log_size;
117         log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
118         memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
119
120         status = efi_call_early(install_configuration_table,
121                                 &linux_eventlog_guid, log_tbl);
122         if (status != EFI_SUCCESS)
123                 goto err_free;
124         return;
125
126 err_free:
127         efi_call_early(free_pool, log_tbl);
128 }
129
130 void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
131 {
132         /* Only try to retrieve the logs in 1.2 format. */
133         efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
134 }