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2023-12-11 6778948f9de86c3cfaf36725a7c87dcff9ba247f 
 kernel/drivers/firmware/efi/libstub/random.c
....@@ -1,192 +1,113 @@
1
+// SPDX-License-Identifier: GPL-2.0
12 /*
23  * Copyright (C) 2016 Linaro Ltd;  <ard.biesheuvel@linaro.org>
3
- *
4
- * This program is free software; you can redistribute it and/or modify
5
- * it under the terms of the GNU General Public License version 2 as
6
- * published by the Free Software Foundation.
7
- *
84  */
95 
106 #include <linux/efi.h>
11
-#include <linux/log2.h>
127 #include <asm/efi.h>
138 
149 #include "efistub.h"
1510 
16
-struct efi_rng_protocol {
17
-	efi_status_t (*get_info)(struct efi_rng_protocol *,
18
-				 unsigned long *, efi_guid_t *);
19
-	efi_status_t (*get_rng)(struct efi_rng_protocol *,
20
-				efi_guid_t *, unsigned long, u8 *out);
11
+typedef union efi_rng_protocol efi_rng_protocol_t;
12
+
13
+union efi_rng_protocol {
14
+	struct {
15
+		efi_status_t (__efiapi *get_info)(efi_rng_protocol_t *,
16
+						  unsigned long *,
17
+						  efi_guid_t *);
18
+		efi_status_t (__efiapi *get_rng)(efi_rng_protocol_t *,
19
+						 efi_guid_t *, unsigned long,
20
+						 u8 *out);
21
+	};
22
+	struct {
23
+		u32 get_info;
24
+		u32 get_rng;
25
+	} mixed_mode;
2126 };
2227 
23
-efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg,
24
-				  unsigned long size, u8 *out)
28
+/**
29
+ * efi_get_random_bytes() - fill a buffer with random bytes
30
+ * @size:	size of the buffer
31
+ * @out:	caller allocated buffer to receive the random bytes
32
+ *
33
+ * The call will fail if either the firmware does not implement the
34
+ * EFI_RNG_PROTOCOL or there are not enough random bytes available to fill
35
+ * the buffer.
36
+ *
37
+ * Return:	status code
38
+ */
39
+efi_status_t efi_get_random_bytes(unsigned long size, u8 *out)
2540 {
2641 	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
2742 	efi_status_t status;
28
-	struct efi_rng_protocol *rng;
43
+	efi_rng_protocol_t *rng = NULL;
2944 
30
-	status = efi_call_early(locate_protocol, &rng_proto, NULL,
31
-				(void **)&rng);
45
+	status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng);
3246 	if (status != EFI_SUCCESS)
3347 		return status;
3448 
35
-	return rng->get_rng(rng, NULL, size, out);
49
+	return efi_call_proto(rng, get_rng, NULL, size, out);
3650 }
3751 
38
-/*
39
- * Return the number of slots covered by this entry, i.e., the number of
40
- * addresses it covers that are suitably aligned and supply enough room
41
- * for the allocation.
52
+/**
53
+ * efi_random_get_seed() - provide random seed as configuration table
54
+ *
55
+ * The EFI_RNG_PROTOCOL is used to read random bytes. These random bytes are
56
+ * saved as a configuration table which can be used as entropy by the kernel
57
+ * for the initialization of its pseudo random number generator.
58
+ *
59
+ * If the EFI_RNG_PROTOCOL is not available or there are not enough random bytes
60
+ * available, the configuration table will not be installed and an error code
61
+ * will be returned.
62
+ *
63
+ * Return:	status code
4264  */
43
-static unsigned long get_entry_num_slots(efi_memory_desc_t *md,
44
-					 unsigned long size,
45
-					 unsigned long align_shift)
46
-{
47
-	unsigned long align = 1UL << align_shift;
48
-	u64 first_slot, last_slot, region_end;
49
-
50
-	if (md->type != EFI_CONVENTIONAL_MEMORY)
51
-		return 0;
52
-
53
-	region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1);
54
-
55
-	first_slot = round_up(md->phys_addr, align);
56
-	last_slot = round_down(region_end - size + 1, align);
57
-
58
-	if (first_slot > last_slot)
59
-		return 0;
60
-
61
-	return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1;
62
-}
63
-
64
-/*
65
- * The UEFI memory descriptors have a virtual address field that is only used
66
- * when installing the virtual mapping using SetVirtualAddressMap(). Since it
67
- * is unused here, we can reuse it to keep track of each descriptor's slot
68
- * count.
69
- */
70
-#define MD_NUM_SLOTS(md)	((md)->virt_addr)
71
-
72
-efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg,
73
-			      unsigned long size,
74
-			      unsigned long align,
75
-			      unsigned long *addr,
76
-			      unsigned long random_seed)
77
-{
78
-	unsigned long map_size, desc_size, total_slots = 0, target_slot;
79
-	unsigned long buff_size;
80
-	efi_status_t status;
81
-	efi_memory_desc_t *memory_map;
82
-	int map_offset;
83
-	struct efi_boot_memmap map;
84
-
85
-	map.map =	&memory_map;
86
-	map.map_size =	&map_size;
87
-	map.desc_size =	&desc_size;
88
-	map.desc_ver =	NULL;
89
-	map.key_ptr =	NULL;
90
-	map.buff_size =	&buff_size;
91
-
92
-	status = efi_get_memory_map(sys_table_arg, &map);
93
-	if (status != EFI_SUCCESS)
94
-		return status;
95
-
96
-	if (align < EFI_ALLOC_ALIGN)
97
-		align = EFI_ALLOC_ALIGN;
98
-
99
-	/* count the suitable slots in each memory map entry */
100
-	for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
101
-		efi_memory_desc_t *md = (void *)memory_map + map_offset;
102
-		unsigned long slots;
103
-
104
-		slots = get_entry_num_slots(md, size, ilog2(align));
105
-		MD_NUM_SLOTS(md) = slots;
106
-		total_slots += slots;
107
-	}
108
-
109
-	/* find a random number between 0 and total_slots */
110
-	target_slot = (total_slots * (u16)random_seed) >> 16;
111
-
112
-	/*
113
-	 * target_slot is now a value in the range [0, total_slots), and so
114
-	 * it corresponds with exactly one of the suitable slots we recorded
115
-	 * when iterating over the memory map the first time around.
116
-	 *
117
-	 * So iterate over the memory map again, subtracting the number of
118
-	 * slots of each entry at each iteration, until we have found the entry
119
-	 * that covers our chosen slot. Use the residual value of target_slot
120
-	 * to calculate the randomly chosen address, and allocate it directly
121
-	 * using EFI_ALLOCATE_ADDRESS.
122
-	 */
123
-	for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
124
-		efi_memory_desc_t *md = (void *)memory_map + map_offset;
125
-		efi_physical_addr_t target;
126
-		unsigned long pages;
127
-
128
-		if (target_slot >= MD_NUM_SLOTS(md)) {
129
-			target_slot -= MD_NUM_SLOTS(md);
130
-			continue;
131
-		}
132
-
133
-		target = round_up(md->phys_addr, align) + target_slot * align;
134
-		pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
135
-
136
-		status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
137
-					EFI_LOADER_DATA, pages, &target);
138
-		if (status == EFI_SUCCESS)
139
-			*addr = target;
140
-		break;
141
-	}
142
-
143
-	efi_call_early(free_pool, memory_map);
144
-
145
-	return status;
146
-}
147
-
148
-efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg)
65
+efi_status_t efi_random_get_seed(void)
14966 {
15067 	efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID;
15168 	efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW;
15269 	efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID;
153
-	struct efi_rng_protocol *rng;
154
-	struct linux_efi_random_seed *seed;
70
+	efi_rng_protocol_t *rng = NULL;
71
+	struct linux_efi_random_seed *seed = NULL;
15572 	efi_status_t status;
15673 
157
-	status = efi_call_early(locate_protocol, &rng_proto, NULL,
158
-				(void **)&rng);
74
+	status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng);
15975 	if (status != EFI_SUCCESS)
16076 		return status;
16177 
162
-	status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA,
163
-				sizeof(*seed) + EFI_RANDOM_SEED_SIZE,
164
-				(void **)&seed);
78
+	/*
79
+	 * Use EFI_ACPI_RECLAIM_MEMORY here so that it is guaranteed that the
80
+	 * allocation will survive a kexec reboot (although we refresh the seed
81
+	 * beforehand)
82
+	 */
83
+	status = efi_bs_call(allocate_pool, EFI_ACPI_RECLAIM_MEMORY,
84
+			     sizeof(*seed) + EFI_RANDOM_SEED_SIZE,
85
+			     (void **)&seed);
16586 	if (status != EFI_SUCCESS)
16687 		return status;
16788 
168
-	status = rng->get_rng(rng, &rng_algo_raw, EFI_RANDOM_SEED_SIZE,
169
-			      seed->bits);
89
+	status = efi_call_proto(rng, get_rng, &rng_algo_raw,
90
+				 EFI_RANDOM_SEED_SIZE, seed->bits);
91
+
17092 	if (status == EFI_UNSUPPORTED)
17193 		/*
17294 		 * Use whatever algorithm we have available if the raw algorithm
17395 		 * is not implemented.
17496 		 */
175
-		status = rng->get_rng(rng, NULL, EFI_RANDOM_SEED_SIZE,
176
-				      seed->bits);
97
+		status = efi_call_proto(rng, get_rng, NULL,
98
+					EFI_RANDOM_SEED_SIZE, seed->bits);
17799 
178100 	if (status != EFI_SUCCESS)
179101 		goto err_freepool;
180102 
181103 	seed->size = EFI_RANDOM_SEED_SIZE;
182
-	status = efi_call_early(install_configuration_table, &rng_table_guid,
183
-				seed);
104
+	status = efi_bs_call(install_configuration_table, &rng_table_guid, seed);
184105 	if (status != EFI_SUCCESS)
185106 		goto err_freepool;
186107 
187108 	return EFI_SUCCESS;
188109 
189110 err_freepool:
190
-	efi_call_early(free_pool, seed);
111
+	efi_bs_call(free_pool, seed);
191112 	return status;
192113 }