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 "compressed/decompressor.h" 11 #include "boot.h" 12 13 #define PRNG_MODE_TDES 1 14 #define PRNG_MODE_SHA512 2 15 #define PRNG_MODE_TRNG 3 16 17 struct prno_parm { 18 u32 res; 19 u32 reseed_counter; 20 u64 stream_bytes; 21 u8 V[112]; 22 u8 C[112]; 23 }; 24 25 struct prng_parm { 26 u8 parm_block[32]; 27 u32 reseed_counter; 28 u64 byte_counter; 29 }; 30 31 static int check_prng(void) 32 { 33 if (!cpacf_query_func(CPACF_KMC, CPACF_KMC_PRNG)) { 34 sclp_early_printk("KASLR disabled: CPU has no PRNG\n"); 35 return 0; 36 } 37 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) 38 return PRNG_MODE_TRNG; 39 if (cpacf_query_func(CPACF_PRNO, CPACF_PRNO_SHA512_DRNG_GEN)) 40 return PRNG_MODE_SHA512; 41 else 42 return PRNG_MODE_TDES; 43 } 44 45 static unsigned long get_random(unsigned long limit) 46 { 47 struct prng_parm prng = { 48 /* initial parameter block for tdes mode, copied from libica */ 49 .parm_block = { 50 0x0F, 0x2B, 0x8E, 0x63, 0x8C, 0x8E, 0xD2, 0x52, 51 0x64, 0xB7, 0xA0, 0x7B, 0x75, 0x28, 0xB8, 0xF4, 52 0x75, 0x5F, 0xD2, 0xA6, 0x8D, 0x97, 0x11, 0xFF, 53 0x49, 0xD8, 0x23, 0xF3, 0x7E, 0x21, 0xEC, 0xA0 54 }, 55 }; 56 unsigned long seed, random; 57 struct prno_parm prno; 58 __u64 entropy[4]; 59 int mode, i; 60 61 mode = check_prng(); 62 seed = get_tod_clock_fast(); 63 switch (mode) { 64 case PRNG_MODE_TRNG: 65 cpacf_trng(NULL, 0, (u8 *) &random, sizeof(random)); 66 break; 67 case PRNG_MODE_SHA512: 68 cpacf_prno(CPACF_PRNO_SHA512_DRNG_SEED, &prno, NULL, 0, 69 (u8 *) &seed, sizeof(seed)); 70 cpacf_prno(CPACF_PRNO_SHA512_DRNG_GEN, &prno, (u8 *) &random, 71 sizeof(random), NULL, 0); 72 break; 73 case PRNG_MODE_TDES: 74 /* add entropy */ 75 *(unsigned long *) prng.parm_block ^= seed; 76 for (i = 0; i < 16; i++) { 77 cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, 78 (u8 *) entropy, (u8 *) entropy, 79 sizeof(entropy)); 80 memcpy(prng.parm_block, entropy, sizeof(entropy)); 81 } 82 random = seed; 83 cpacf_kmc(CPACF_KMC_PRNG, prng.parm_block, (u8 *) &random, 84 (u8 *) &random, sizeof(random)); 85 break; 86 default: 87 random = 0; 88 } 89 return random % limit; 90 } 91 92 unsigned long get_random_base(unsigned long safe_addr) 93 { 94 unsigned long memory_limit = memory_end_set ? memory_end : 0; 95 unsigned long base, start, end, kernel_size; 96 unsigned long block_sum, offset; 97 unsigned long kasan_needs; 98 int i; 99 100 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE) { 101 if (safe_addr < INITRD_START + INITRD_SIZE) 102 safe_addr = INITRD_START + INITRD_SIZE; 103 } 104 safe_addr = ALIGN(safe_addr, THREAD_SIZE); 105 106 if ((IS_ENABLED(CONFIG_KASAN))) { 107 /* 108 * Estimate kasan memory requirements, which it will reserve 109 * at the very end of available physical memory. To estimate 110 * that, we take into account that kasan would require 111 * 1/8 of available physical memory (for shadow memory) + 112 * creating page tables for the whole memory + shadow memory 113 * region (1 + 1/8). To keep page tables estimates simple take 114 * the double of combined ptes size. 115 */ 116 memory_limit = get_mem_detect_end(); 117 if (memory_end_set && memory_limit > memory_end) 118 memory_limit = memory_end; 119 120 /* for shadow memory */ 121 kasan_needs = memory_limit / 8; 122 /* for paging structures */ 123 kasan_needs += (memory_limit + kasan_needs) / PAGE_SIZE / 124 _PAGE_ENTRIES * _PAGE_TABLE_SIZE * 2; 125 memory_limit -= kasan_needs; 126 } 127 128 kernel_size = vmlinux.image_size + vmlinux.bss_size; 129 block_sum = 0; 130 for_each_mem_detect_block(i, &start, &end) { 131 if (memory_limit) { 132 if (start >= memory_limit) 133 break; 134 if (end > memory_limit) 135 end = memory_limit; 136 } 137 if (end - start < kernel_size) 138 continue; 139 block_sum += end - start - kernel_size; 140 } 141 if (!block_sum) { 142 sclp_early_printk("KASLR disabled: not enough memory\n"); 143 return 0; 144 } 145 146 base = get_random(block_sum); 147 if (base == 0) 148 return 0; 149 if (base < safe_addr) 150 base = safe_addr; 151 block_sum = offset = 0; 152 for_each_mem_detect_block(i, &start, &end) { 153 if (memory_limit) { 154 if (start >= memory_limit) 155 break; 156 if (end > memory_limit) 157 end = memory_limit; 158 } 159 if (end - start < kernel_size) 160 continue; 161 block_sum += end - start - kernel_size; 162 if (base <= block_sum) { 163 base = start + base - offset; 164 base = ALIGN_DOWN(base, THREAD_SIZE); 165 break; 166 } 167 offset = block_sum; 168 } 169 return base; 170 } 171