14febfb8dSArd Biesheuvel // SPDX-License-Identifier: GPL-2.0 2e4fbf476SArd Biesheuvel /* 3e4fbf476SArd Biesheuvel * Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org> 4e4fbf476SArd Biesheuvel */ 5e4fbf476SArd Biesheuvel 6e4fbf476SArd Biesheuvel #include <linux/efi.h> 7a6a14469SArd Biesheuvel #include <linux/log2.h> 8e4fbf476SArd Biesheuvel #include <asm/efi.h> 9e4fbf476SArd Biesheuvel 10e4fbf476SArd Biesheuvel #include "efistub.h" 11e4fbf476SArd Biesheuvel 1241e8a7c2SDominik Brodowski typedef struct efi_rng_protocol efi_rng_protocol_t; 1341e8a7c2SDominik Brodowski 1441e8a7c2SDominik Brodowski typedef struct { 1541e8a7c2SDominik Brodowski u32 get_info; 1641e8a7c2SDominik Brodowski u32 get_rng; 1741e8a7c2SDominik Brodowski } efi_rng_protocol_32_t; 1841e8a7c2SDominik Brodowski 1941e8a7c2SDominik Brodowski typedef struct { 2041e8a7c2SDominik Brodowski u64 get_info; 2141e8a7c2SDominik Brodowski u64 get_rng; 2241e8a7c2SDominik Brodowski } efi_rng_protocol_64_t; 2341e8a7c2SDominik Brodowski 24e4fbf476SArd Biesheuvel struct efi_rng_protocol { 25e4fbf476SArd Biesheuvel efi_status_t (*get_info)(struct efi_rng_protocol *, 26e4fbf476SArd Biesheuvel unsigned long *, efi_guid_t *); 27e4fbf476SArd Biesheuvel efi_status_t (*get_rng)(struct efi_rng_protocol *, 28e4fbf476SArd Biesheuvel efi_guid_t *, unsigned long, u8 *out); 29e4fbf476SArd Biesheuvel }; 30e4fbf476SArd Biesheuvel 31e4fbf476SArd Biesheuvel efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg, 32e4fbf476SArd Biesheuvel unsigned long size, u8 *out) 33e4fbf476SArd Biesheuvel { 34e4fbf476SArd Biesheuvel efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; 35e4fbf476SArd Biesheuvel efi_status_t status; 36818c7ce7SHans de Goede struct efi_rng_protocol *rng = NULL; 37e4fbf476SArd Biesheuvel 38e4fbf476SArd Biesheuvel status = efi_call_early(locate_protocol, &rng_proto, NULL, 39e4fbf476SArd Biesheuvel (void **)&rng); 40e4fbf476SArd Biesheuvel if (status != EFI_SUCCESS) 41e4fbf476SArd Biesheuvel return status; 42e4fbf476SArd Biesheuvel 4341e8a7c2SDominik Brodowski return efi_call_proto(efi_rng_protocol, get_rng, rng, NULL, size, out); 44e4fbf476SArd Biesheuvel } 452ddbfc81SArd Biesheuvel 462ddbfc81SArd Biesheuvel /* 472ddbfc81SArd Biesheuvel * Return the number of slots covered by this entry, i.e., the number of 482ddbfc81SArd Biesheuvel * addresses it covers that are suitably aligned and supply enough room 492ddbfc81SArd Biesheuvel * for the allocation. 502ddbfc81SArd Biesheuvel */ 512ddbfc81SArd Biesheuvel static unsigned long get_entry_num_slots(efi_memory_desc_t *md, 522ddbfc81SArd Biesheuvel unsigned long size, 53a6a14469SArd Biesheuvel unsigned long align_shift) 542ddbfc81SArd Biesheuvel { 55a6a14469SArd Biesheuvel unsigned long align = 1UL << align_shift; 56018edcfaSArd Biesheuvel u64 first_slot, last_slot, region_end; 572ddbfc81SArd Biesheuvel 582ddbfc81SArd Biesheuvel if (md->type != EFI_CONVENTIONAL_MEMORY) 592ddbfc81SArd Biesheuvel return 0; 602ddbfc81SArd Biesheuvel 6116993c0fSDan Williams if (efi_soft_reserve_enabled() && 6216993c0fSDan Williams (md->attribute & EFI_MEMORY_SP)) 6316993c0fSDan Williams return 0; 6416993c0fSDan Williams 65018edcfaSArd Biesheuvel region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1); 662ddbfc81SArd Biesheuvel 67018edcfaSArd Biesheuvel first_slot = round_up(md->phys_addr, align); 68018edcfaSArd Biesheuvel last_slot = round_down(region_end - size + 1, align); 69018edcfaSArd Biesheuvel 70018edcfaSArd Biesheuvel if (first_slot > last_slot) 712ddbfc81SArd Biesheuvel return 0; 722ddbfc81SArd Biesheuvel 73018edcfaSArd Biesheuvel return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1; 742ddbfc81SArd Biesheuvel } 752ddbfc81SArd Biesheuvel 762ddbfc81SArd Biesheuvel /* 772ddbfc81SArd Biesheuvel * The UEFI memory descriptors have a virtual address field that is only used 782ddbfc81SArd Biesheuvel * when installing the virtual mapping using SetVirtualAddressMap(). Since it 792ddbfc81SArd Biesheuvel * is unused here, we can reuse it to keep track of each descriptor's slot 802ddbfc81SArd Biesheuvel * count. 812ddbfc81SArd Biesheuvel */ 822ddbfc81SArd Biesheuvel #define MD_NUM_SLOTS(md) ((md)->virt_addr) 832ddbfc81SArd Biesheuvel 842ddbfc81SArd Biesheuvel efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, 852ddbfc81SArd Biesheuvel unsigned long size, 862ddbfc81SArd Biesheuvel unsigned long align, 872ddbfc81SArd Biesheuvel unsigned long *addr, 882ddbfc81SArd Biesheuvel unsigned long random_seed) 892ddbfc81SArd Biesheuvel { 902ddbfc81SArd Biesheuvel unsigned long map_size, desc_size, total_slots = 0, target_slot; 91dadb57abSJeffrey Hugo unsigned long buff_size; 922ddbfc81SArd Biesheuvel efi_status_t status; 932ddbfc81SArd Biesheuvel efi_memory_desc_t *memory_map; 942ddbfc81SArd Biesheuvel int map_offset; 95dadb57abSJeffrey Hugo struct efi_boot_memmap map; 962ddbfc81SArd Biesheuvel 97dadb57abSJeffrey Hugo map.map = &memory_map; 98dadb57abSJeffrey Hugo map.map_size = &map_size; 99dadb57abSJeffrey Hugo map.desc_size = &desc_size; 100dadb57abSJeffrey Hugo map.desc_ver = NULL; 101dadb57abSJeffrey Hugo map.key_ptr = NULL; 102dadb57abSJeffrey Hugo map.buff_size = &buff_size; 103dadb57abSJeffrey Hugo 104dadb57abSJeffrey Hugo status = efi_get_memory_map(sys_table_arg, &map); 1052ddbfc81SArd Biesheuvel if (status != EFI_SUCCESS) 1062ddbfc81SArd Biesheuvel return status; 1072ddbfc81SArd Biesheuvel 1082ddbfc81SArd Biesheuvel if (align < EFI_ALLOC_ALIGN) 1092ddbfc81SArd Biesheuvel align = EFI_ALLOC_ALIGN; 1102ddbfc81SArd Biesheuvel 1112ddbfc81SArd Biesheuvel /* count the suitable slots in each memory map entry */ 1122ddbfc81SArd Biesheuvel for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { 1132ddbfc81SArd Biesheuvel efi_memory_desc_t *md = (void *)memory_map + map_offset; 1142ddbfc81SArd Biesheuvel unsigned long slots; 1152ddbfc81SArd Biesheuvel 116a6a14469SArd Biesheuvel slots = get_entry_num_slots(md, size, ilog2(align)); 1172ddbfc81SArd Biesheuvel MD_NUM_SLOTS(md) = slots; 1182ddbfc81SArd Biesheuvel total_slots += slots; 1192ddbfc81SArd Biesheuvel } 1202ddbfc81SArd Biesheuvel 1212ddbfc81SArd Biesheuvel /* find a random number between 0 and total_slots */ 1222ddbfc81SArd Biesheuvel target_slot = (total_slots * (u16)random_seed) >> 16; 1232ddbfc81SArd Biesheuvel 1242ddbfc81SArd Biesheuvel /* 1252ddbfc81SArd Biesheuvel * target_slot is now a value in the range [0, total_slots), and so 1262ddbfc81SArd Biesheuvel * it corresponds with exactly one of the suitable slots we recorded 1272ddbfc81SArd Biesheuvel * when iterating over the memory map the first time around. 1282ddbfc81SArd Biesheuvel * 1292ddbfc81SArd Biesheuvel * So iterate over the memory map again, subtracting the number of 1302ddbfc81SArd Biesheuvel * slots of each entry at each iteration, until we have found the entry 1312ddbfc81SArd Biesheuvel * that covers our chosen slot. Use the residual value of target_slot 1322ddbfc81SArd Biesheuvel * to calculate the randomly chosen address, and allocate it directly 1332ddbfc81SArd Biesheuvel * using EFI_ALLOCATE_ADDRESS. 1342ddbfc81SArd Biesheuvel */ 1352ddbfc81SArd Biesheuvel for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { 1362ddbfc81SArd Biesheuvel efi_memory_desc_t *md = (void *)memory_map + map_offset; 1372ddbfc81SArd Biesheuvel efi_physical_addr_t target; 1382ddbfc81SArd Biesheuvel unsigned long pages; 1392ddbfc81SArd Biesheuvel 1402ddbfc81SArd Biesheuvel if (target_slot >= MD_NUM_SLOTS(md)) { 1412ddbfc81SArd Biesheuvel target_slot -= MD_NUM_SLOTS(md); 1422ddbfc81SArd Biesheuvel continue; 1432ddbfc81SArd Biesheuvel } 1442ddbfc81SArd Biesheuvel 1452ddbfc81SArd Biesheuvel target = round_up(md->phys_addr, align) + target_slot * align; 1462ddbfc81SArd Biesheuvel pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE; 1472ddbfc81SArd Biesheuvel 1482ddbfc81SArd Biesheuvel status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, 1492ddbfc81SArd Biesheuvel EFI_LOADER_DATA, pages, &target); 1502ddbfc81SArd Biesheuvel if (status == EFI_SUCCESS) 1512ddbfc81SArd Biesheuvel *addr = target; 1522ddbfc81SArd Biesheuvel break; 1532ddbfc81SArd Biesheuvel } 1542ddbfc81SArd Biesheuvel 1552ddbfc81SArd Biesheuvel efi_call_early(free_pool, memory_map); 1562ddbfc81SArd Biesheuvel 1572ddbfc81SArd Biesheuvel return status; 1582ddbfc81SArd Biesheuvel } 159568bc4e8SArd Biesheuvel 160568bc4e8SArd Biesheuvel efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg) 161568bc4e8SArd Biesheuvel { 162568bc4e8SArd Biesheuvel efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; 163568bc4e8SArd Biesheuvel efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; 164568bc4e8SArd Biesheuvel efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; 165818c7ce7SHans de Goede struct efi_rng_protocol *rng = NULL; 166818c7ce7SHans de Goede struct linux_efi_random_seed *seed = NULL; 167568bc4e8SArd Biesheuvel efi_status_t status; 168568bc4e8SArd Biesheuvel 169568bc4e8SArd Biesheuvel status = efi_call_early(locate_protocol, &rng_proto, NULL, 170568bc4e8SArd Biesheuvel (void **)&rng); 171568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 172568bc4e8SArd Biesheuvel return status; 173568bc4e8SArd Biesheuvel 174568bc4e8SArd Biesheuvel status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA, 175c2ceb5fdSArd Biesheuvel sizeof(*seed) + EFI_RANDOM_SEED_SIZE, 176568bc4e8SArd Biesheuvel (void **)&seed); 177568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 178568bc4e8SArd Biesheuvel return status; 179568bc4e8SArd Biesheuvel 18041e8a7c2SDominik Brodowski status = efi_call_proto(efi_rng_protocol, get_rng, rng, &rng_algo_raw, 18141e8a7c2SDominik Brodowski EFI_RANDOM_SEED_SIZE, seed->bits); 18241e8a7c2SDominik Brodowski 183568bc4e8SArd Biesheuvel if (status == EFI_UNSUPPORTED) 184568bc4e8SArd Biesheuvel /* 185568bc4e8SArd Biesheuvel * Use whatever algorithm we have available if the raw algorithm 186568bc4e8SArd Biesheuvel * is not implemented. 187568bc4e8SArd Biesheuvel */ 18841e8a7c2SDominik Brodowski status = efi_call_proto(efi_rng_protocol, get_rng, rng, NULL, 18941e8a7c2SDominik Brodowski EFI_RANDOM_SEED_SIZE, seed->bits); 190568bc4e8SArd Biesheuvel 191568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 192568bc4e8SArd Biesheuvel goto err_freepool; 193568bc4e8SArd Biesheuvel 194c2ceb5fdSArd Biesheuvel seed->size = EFI_RANDOM_SEED_SIZE; 195568bc4e8SArd Biesheuvel status = efi_call_early(install_configuration_table, &rng_table_guid, 196568bc4e8SArd Biesheuvel seed); 197568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 198568bc4e8SArd Biesheuvel goto err_freepool; 199568bc4e8SArd Biesheuvel 200568bc4e8SArd Biesheuvel return EFI_SUCCESS; 201568bc4e8SArd Biesheuvel 202568bc4e8SArd Biesheuvel err_freepool: 203568bc4e8SArd Biesheuvel efi_call_early(free_pool, seed); 204568bc4e8SArd Biesheuvel return status; 205568bc4e8SArd Biesheuvel } 206