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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright IBM Corp. 2019
4 */
5#include <linux/pgtable.h>
6#include <asm/physmem_info.h>
7#include <asm/cpacf.h>
8#include <asm/timex.h>
9#include <asm/sclp.h>
10#include <asm/kasan.h>
11#include "decompressor.h"
12#include "boot.h"
13
14#define PRNG_MODE_TDES 1
15#define PRNG_MODE_SHA512 2
16#define PRNG_MODE_TRNG 3
17
18struct prno_parm {
19 u32 res;
20 u32 reseed_counter;
21 u64 stream_bytes;
22 u8 V[112];
23 u8 C[112];
24};
25
26struct prng_parm {
27 u8 parm_block[32];
28 u32 reseed_counter;
29 u64 byte_counter;
30};
31
32static int check_prng(void)
33{
34 if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG)) {
35 boot_printk("KASLR disabled: CPU has no PRNG\n");
36 return 0;
37 }
38 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
39 return PRNG_MODE_TRNG;
40 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN))
41 return PRNG_MODE_SHA512;
42 else
43 return PRNG_MODE_TDES;
44}
45
46int get_random(unsigned long limit, unsigned long *value)
47{
48 struct prng_parm prng = {
49 /* initial parameter block for tdes mode, copied from libica */
50 .parm_block = {
51 0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
52 0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
53 0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
54 0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0
55 },
56 };
57 unsigned long seed, random;
58 struct prno_parm prno;
59 __u64 entropy[4];
60 int mode, i;
61
62 mode = check_prng();
63 seed = get_tod_clock_fast();
64 switch (mode) {
65 case PRNG_MODE_TRNG:
66 cpacf_trng(NULL, 0, (u8 *) &random, sizeof(random));
67 break;
68 case PRNG_MODE_SHA512:
69 cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, &prno, NULL, 0,
70 (u8 *) &seed, sizeof(seed));
71 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, &prno, (u8 *) &random,
72 sizeof(random), NULL, 0);
73 break;
74 case PRNG_MODE_TDES:
75 /* add entropy */
76 *(unsigned long *) prng.parm_block ^= seed;
77 for (i = 0; i < 16; i++) {
78 cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block,
79 (u8 *) entropy, (u8 *) entropy,
80 sizeof(entropy));
81 memcpy(prng.parm_block, entropy, sizeof(entropy));
82 }
83 random = seed;
84 cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, (u8 *) &random,
85 (u8 *) &random, sizeof(random));
86 break;
87 default:
88 return -1;
89 }
90 *value = random % limit;
91 return 0;
92}
93
94static void sort_reserved_ranges(struct reserved_range *res, unsigned long size)
95{
96 struct reserved_range tmp;
97 int i, j;
98
99 for (i = 1; i < size; i++) {
100 tmp = res[i];
101 for (j = i - 1; j >= 0 && res[j].start > tmp.start; j--)
102 res[j + 1] = res[j];
103 res[j + 1] = tmp;
104 }
105}
106
107static unsigned long iterate_valid_positions(unsigned long size, unsigned long align,
108 unsigned long _min, unsigned long _max,
109 struct reserved_range *res, size_t res_count,
110 bool pos_count, unsigned long find_pos)
111{
112 unsigned long start, end, tmp_end, range_pos, pos = 0;
113 struct reserved_range *res_end = res + res_count;
114 struct reserved_range *skip_res;
115 int i;
116
117 align = max(align, 8UL);
118 _min = round_up(_min, align);
119 for_each_physmem_usable_range(i, &start, &end) {
120 if (_min >= end)
121 continue;
122 start = round_up(start, align);
123 if (start >= _max)
124 break;
125 start = max(_min, start);
126 end = min(_max, end);
127
128 while (start + size <= end) {
129 /* skip reserved ranges below the start */
130 while (res && res->end <= start) {
131 res++;
132 if (res >= res_end)
133 res = NULL;
134 }
135 skip_res = NULL;
136 tmp_end = end;
137 /* has intersecting reserved range */
138 if (res && res->start < end) {
139 skip_res = res;
140 tmp_end = res->start;
141 }
142 if (start + size <= tmp_end) {
143 range_pos = (tmp_end - start - size) / align + 1;
144 if (pos_count) {
145 pos += range_pos;
146 } else {
147 if (range_pos >= find_pos)
148 return start + (find_pos - 1) * align;
149 find_pos -= range_pos;
150 }
151 }
152 if (!skip_res)
153 break;
154 start = round_up(skip_res->end, align);
155 }
156 }
157
158 return pos_count ? pos : 0;
159}
160
161/*
162 * Two types of decompressor memory allocations/reserves are considered
163 * differently.
164 *
165 * "Static" or "single" allocations are done via physmem_alloc_range() and
166 * physmem_reserve(), and they are listed in physmem_info.reserved[]. Each
167 * type of "static" allocation can only have one allocation per type and
168 * cannot have chains.
169 *
170 * On the other hand, "dynamic" or "repetitive" allocations are done via
171 * physmem_alloc_top_down(). These allocations are tightly packed together
172 * top down from the end of online memory. physmem_alloc_pos represents
173 * current position where those allocations start.
174 *
175 * Functions randomize_within_range() and iterate_valid_positions()
176 * only consider "dynamic" allocations by never looking above
177 * physmem_alloc_pos. "Static" allocations, however, are explicitly
178 * considered by checking the "res" (reserves) array. The first
179 * reserved_range of a "dynamic" allocation may also be checked along the
180 * way, but it will always be above the maximum value anyway.
181 */
182unsigned long randomize_within_range(unsigned long size, unsigned long align,
183 unsigned long min, unsigned long max)
184{
185 struct reserved_range res[RR_MAX];
186 unsigned long max_pos, pos;
187
188 memcpy(res, physmem_info.reserved, sizeof(res));
189 sort_reserved_ranges(res, ARRAY_SIZE(res));
190 max = min(max, get_physmem_alloc_pos());
191
192 max_pos = iterate_valid_positions(size, align, min, max, res, ARRAY_SIZE(res), true, 0);
193 if (!max_pos)
194 return 0;
195 if (get_random(max_pos, &pos))
196 return 0;
197 return iterate_valid_positions(size, align, min, max, res, ARRAY_SIZE(res), false, pos + 1);
198}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright IBM Corp. 2019
4 */
5#include <linux/pgtable.h>
6#include <asm/mem_detect.h>
7#include <asm/cpacf.h>
8#include <asm/timex.h>
9#include <asm/sclp.h>
10#include <asm/kasan.h>
11#include "compressed/decompressor.h"
12#include "boot.h"
13
14#define PRNG_MODE_TDES 1
15#define PRNG_MODE_SHA512 2
16#define PRNG_MODE_TRNG 3
17
18struct prno_parm {
19 u32 res;
20 u32 reseed_counter;
21 u64 stream_bytes;
22 u8 V[112];
23 u8 C[112];
24};
25
26struct prng_parm {
27 u8 parm_block[32];
28 u32 reseed_counter;
29 u64 byte_counter;
30};
31
32static int check_prng(void)
33{
34 if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG)) {
35 sclp_early_printk("KASLR disabled: CPU has no PRNG\n");
36 return 0;
37 }
38 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG))
39 return PRNG_MODE_TRNG;
40 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN))
41 return PRNG_MODE_SHA512;
42 else
43 return PRNG_MODE_TDES;
44}
45
46static int get_random(unsigned long limit, unsigned long *value)
47{
48 struct prng_parm prng = {
49 /* initial parameter block for tdes mode, copied from libica */
50 .parm_block = {
51 0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52,
52 0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4,
53 0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF,
54 0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0
55 },
56 };
57 unsigned long seed, random;
58 struct prno_parm prno;
59 __u64 entropy[4];
60 int mode, i;
61
62 mode = check_prng();
63 seed = get_tod_clock_fast();
64 switch (mode) {
65 case PRNG_MODE_TRNG:
66 cpacf_trng(NULL, 0, (u8 *) &random, sizeof(random));
67 break;
68 case PRNG_MODE_SHA512:
69 cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, &prno, NULL, 0,
70 (u8 *) &seed, sizeof(seed));
71 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, &prno, (u8 *) &random,
72 sizeof(random), NULL, 0);
73 break;
74 case PRNG_MODE_TDES:
75 /* add entropy */
76 *(unsigned long *) prng.parm_block ^= seed;
77 for (i = 0; i < 16; i++) {
78 cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block,
79 (u8 *) entropy, (u8 *) entropy,
80 sizeof(entropy));
81 memcpy(prng.parm_block, entropy, sizeof(entropy));
82 }
83 random = seed;
84 cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, (u8 *) &random,
85 (u8 *) &random, sizeof(random));
86 break;
87 default:
88 return -1;
89 }
90 *value = random % limit;
91 return 0;
92}
93
94/*
95 * To randomize kernel base address we have to consider several facts:
96 * 1. physical online memory might not be continuous and have holes. mem_detect
97 * info contains list of online memory ranges we should consider.
98 * 2. we have several memory regions which are occupied and we should not
99 * overlap and destroy them. Currently safe_addr tells us the border below
100 * which all those occupied regions are. We are safe to use anything above
101 * safe_addr.
102 * 3. the upper limit might apply as well, even if memory above that limit is
103 * online. Currently those limitations are:
104 * 3.1. Limit set by "mem=" kernel command line option
105 * 3.2. memory reserved at the end for kasan initialization.
106 * 4. kernel base address must be aligned to THREAD_SIZE (kernel stack size).
107 * Which is required for CONFIG_CHECK_STACK. Currently THREAD_SIZE is 4 pages
108 * (16 pages when the kernel is built with kasan enabled)
109 * Assumptions:
110 * 1. kernel size (including .bss size) and upper memory limit are page aligned.
111 * 2. mem_detect memory region start is THREAD_SIZE aligned / end is PAGE_SIZE
112 * aligned (in practice memory configurations granularity on z/VM and LPAR
113 * is 1mb).
114 *
115 * To guarantee uniform distribution of kernel base address among all suitable
116 * addresses we generate random value just once. For that we need to build a
117 * continuous range in which every value would be suitable. We can build this
118 * range by simply counting all suitable addresses (let's call them positions)
119 * which would be valid as kernel base address. To count positions we iterate
120 * over online memory ranges. For each range which is big enough for the
121 * kernel image we count all suitable addresses we can put the kernel image at
122 * that is
123 * (end - start - kernel_size) / THREAD_SIZE + 1
124 * Two functions count_valid_kernel_positions and position_to_address help
125 * to count positions in memory range given and then convert position back
126 * to address.
127 */
128static unsigned long count_valid_kernel_positions(unsigned long kernel_size,
129 unsigned long _min,
130 unsigned long _max)
131{
132 unsigned long start, end, pos = 0;
133 int i;
134
135 for_each_mem_detect_block(i, &start, &end) {
136 if (_min >= end)
137 continue;
138 if (start >= _max)
139 break;
140 start = max(_min, start);
141 end = min(_max, end);
142 if (end - start < kernel_size)
143 continue;
144 pos += (end - start - kernel_size) / THREAD_SIZE + 1;
145 }
146
147 return pos;
148}
149
150static unsigned long position_to_address(unsigned long pos, unsigned long kernel_size,
151 unsigned long _min, unsigned long _max)
152{
153 unsigned long start, end;
154 int i;
155
156 for_each_mem_detect_block(i, &start, &end) {
157 if (_min >= end)
158 continue;
159 if (start >= _max)
160 break;
161 start = max(_min, start);
162 end = min(_max, end);
163 if (end - start < kernel_size)
164 continue;
165 if ((end - start - kernel_size) / THREAD_SIZE + 1 >= pos)
166 return start + (pos - 1) * THREAD_SIZE;
167 pos -= (end - start - kernel_size) / THREAD_SIZE + 1;
168 }
169
170 return 0;
171}
172
173unsigned long get_random_base(unsigned long safe_addr)
174{
175 unsigned long memory_limit = get_mem_detect_end();
176 unsigned long base_pos, max_pos, kernel_size;
177 unsigned long kasan_needs;
178 int i;
179
180 memory_limit = min(memory_limit, ident_map_size);
181
182 /*
183 * Avoid putting kernel in the end of physical memory
184 * which kasan will use for shadow memory and early pgtable
185 * mapping allocations.
186 */
187 memory_limit -= kasan_estimate_memory_needs(memory_limit);
188
189 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE) {
190 if (safe_addr < INITRD_START + INITRD_SIZE)
191 safe_addr = INITRD_START + INITRD_SIZE;
192 }
193 safe_addr = ALIGN(safe_addr, THREAD_SIZE);
194
195 kernel_size = vmlinux.image_size + vmlinux.bss_size;
196 if (safe_addr + kernel_size > memory_limit)
197 return 0;
198
199 max_pos = count_valid_kernel_positions(kernel_size, safe_addr, memory_limit);
200 if (!max_pos) {
201 sclp_early_printk("KASLR disabled: not enough memory\n");
202 return 0;
203 }
204
205 /* we need a value in the range [1, base_pos] inclusive */
206 if (get_random(max_pos, &base_pos))
207 return 0;
208 return position_to_address(base_pos + 1, kernel_size, safe_addr, memory_limit);
209}