1e4fbf476SArd Biesheuvel /* 2e4fbf476SArd Biesheuvel * Copyright (C) 2016 Linaro Ltd; <ard.biesheuvel@linaro.org> 3e4fbf476SArd Biesheuvel * 4e4fbf476SArd Biesheuvel * This program is free software; you can redistribute it and/or modify 5e4fbf476SArd Biesheuvel * it under the terms of the GNU General Public License version 2 as 6e4fbf476SArd Biesheuvel * published by the Free Software Foundation. 7e4fbf476SArd Biesheuvel * 8e4fbf476SArd Biesheuvel */ 9e4fbf476SArd Biesheuvel 10e4fbf476SArd Biesheuvel #include <linux/efi.h> 11a6a14469SArd Biesheuvel #include <linux/log2.h> 12e4fbf476SArd Biesheuvel #include <asm/efi.h> 13e4fbf476SArd Biesheuvel 14e4fbf476SArd Biesheuvel #include "efistub.h" 15e4fbf476SArd Biesheuvel 16e4fbf476SArd Biesheuvel struct efi_rng_protocol { 17e4fbf476SArd Biesheuvel efi_status_t (*get_info)(struct efi_rng_protocol *, 18e4fbf476SArd Biesheuvel unsigned long *, efi_guid_t *); 19e4fbf476SArd Biesheuvel efi_status_t (*get_rng)(struct efi_rng_protocol *, 20e4fbf476SArd Biesheuvel efi_guid_t *, unsigned long, u8 *out); 21e4fbf476SArd Biesheuvel }; 22e4fbf476SArd Biesheuvel 23e4fbf476SArd Biesheuvel efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg, 24e4fbf476SArd Biesheuvel unsigned long size, u8 *out) 25e4fbf476SArd Biesheuvel { 26e4fbf476SArd Biesheuvel efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; 27e4fbf476SArd Biesheuvel efi_status_t status; 28e4fbf476SArd Biesheuvel struct efi_rng_protocol *rng; 29e4fbf476SArd Biesheuvel 30e4fbf476SArd Biesheuvel status = efi_call_early(locate_protocol, &rng_proto, NULL, 31e4fbf476SArd Biesheuvel (void **)&rng); 32e4fbf476SArd Biesheuvel if (status != EFI_SUCCESS) 33e4fbf476SArd Biesheuvel return status; 34e4fbf476SArd Biesheuvel 35e4fbf476SArd Biesheuvel return rng->get_rng(rng, NULL, size, out); 36e4fbf476SArd Biesheuvel } 372ddbfc81SArd Biesheuvel 382ddbfc81SArd Biesheuvel /* 392ddbfc81SArd Biesheuvel * Return the number of slots covered by this entry, i.e., the number of 402ddbfc81SArd Biesheuvel * addresses it covers that are suitably aligned and supply enough room 412ddbfc81SArd Biesheuvel * for the allocation. 422ddbfc81SArd Biesheuvel */ 432ddbfc81SArd Biesheuvel static unsigned long get_entry_num_slots(efi_memory_desc_t *md, 442ddbfc81SArd Biesheuvel unsigned long size, 45a6a14469SArd Biesheuvel unsigned long align_shift) 462ddbfc81SArd Biesheuvel { 47a6a14469SArd Biesheuvel unsigned long align = 1UL << align_shift; 482ddbfc81SArd Biesheuvel u64 start, end; 492ddbfc81SArd Biesheuvel 502ddbfc81SArd Biesheuvel if (md->type != EFI_CONVENTIONAL_MEMORY) 512ddbfc81SArd Biesheuvel return 0; 522ddbfc81SArd Biesheuvel 532ddbfc81SArd Biesheuvel start = round_up(md->phys_addr, align); 542ddbfc81SArd Biesheuvel end = round_down(md->phys_addr + md->num_pages * EFI_PAGE_SIZE - size, 552ddbfc81SArd Biesheuvel align); 562ddbfc81SArd Biesheuvel 572ddbfc81SArd Biesheuvel if (start > end) 582ddbfc81SArd Biesheuvel return 0; 592ddbfc81SArd Biesheuvel 60a6a14469SArd Biesheuvel return (end - start + 1) >> align_shift; 612ddbfc81SArd Biesheuvel } 622ddbfc81SArd Biesheuvel 632ddbfc81SArd Biesheuvel /* 642ddbfc81SArd Biesheuvel * The UEFI memory descriptors have a virtual address field that is only used 652ddbfc81SArd Biesheuvel * when installing the virtual mapping using SetVirtualAddressMap(). Since it 662ddbfc81SArd Biesheuvel * is unused here, we can reuse it to keep track of each descriptor's slot 672ddbfc81SArd Biesheuvel * count. 682ddbfc81SArd Biesheuvel */ 692ddbfc81SArd Biesheuvel #define MD_NUM_SLOTS(md) ((md)->virt_addr) 702ddbfc81SArd Biesheuvel 712ddbfc81SArd Biesheuvel efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, 722ddbfc81SArd Biesheuvel unsigned long size, 732ddbfc81SArd Biesheuvel unsigned long align, 742ddbfc81SArd Biesheuvel unsigned long *addr, 752ddbfc81SArd Biesheuvel unsigned long random_seed) 762ddbfc81SArd Biesheuvel { 772ddbfc81SArd Biesheuvel unsigned long map_size, desc_size, total_slots = 0, target_slot; 78dadb57abSJeffrey Hugo unsigned long buff_size; 792ddbfc81SArd Biesheuvel efi_status_t status; 802ddbfc81SArd Biesheuvel efi_memory_desc_t *memory_map; 812ddbfc81SArd Biesheuvel int map_offset; 82dadb57abSJeffrey Hugo struct efi_boot_memmap map; 832ddbfc81SArd Biesheuvel 84dadb57abSJeffrey Hugo map.map = &memory_map; 85dadb57abSJeffrey Hugo map.map_size = &map_size; 86dadb57abSJeffrey Hugo map.desc_size = &desc_size; 87dadb57abSJeffrey Hugo map.desc_ver = NULL; 88dadb57abSJeffrey Hugo map.key_ptr = NULL; 89dadb57abSJeffrey Hugo map.buff_size = &buff_size; 90dadb57abSJeffrey Hugo 91dadb57abSJeffrey Hugo status = efi_get_memory_map(sys_table_arg, &map); 922ddbfc81SArd Biesheuvel if (status != EFI_SUCCESS) 932ddbfc81SArd Biesheuvel return status; 942ddbfc81SArd Biesheuvel 952ddbfc81SArd Biesheuvel if (align < EFI_ALLOC_ALIGN) 962ddbfc81SArd Biesheuvel align = EFI_ALLOC_ALIGN; 972ddbfc81SArd Biesheuvel 982ddbfc81SArd Biesheuvel /* count the suitable slots in each memory map entry */ 992ddbfc81SArd Biesheuvel for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { 1002ddbfc81SArd Biesheuvel efi_memory_desc_t *md = (void *)memory_map + map_offset; 1012ddbfc81SArd Biesheuvel unsigned long slots; 1022ddbfc81SArd Biesheuvel 103a6a14469SArd Biesheuvel slots = get_entry_num_slots(md, size, ilog2(align)); 1042ddbfc81SArd Biesheuvel MD_NUM_SLOTS(md) = slots; 1052ddbfc81SArd Biesheuvel total_slots += slots; 1062ddbfc81SArd Biesheuvel } 1072ddbfc81SArd Biesheuvel 1082ddbfc81SArd Biesheuvel /* find a random number between 0 and total_slots */ 1092ddbfc81SArd Biesheuvel target_slot = (total_slots * (u16)random_seed) >> 16; 1102ddbfc81SArd Biesheuvel 1112ddbfc81SArd Biesheuvel /* 1122ddbfc81SArd Biesheuvel * target_slot is now a value in the range [0, total_slots), and so 1132ddbfc81SArd Biesheuvel * it corresponds with exactly one of the suitable slots we recorded 1142ddbfc81SArd Biesheuvel * when iterating over the memory map the first time around. 1152ddbfc81SArd Biesheuvel * 1162ddbfc81SArd Biesheuvel * So iterate over the memory map again, subtracting the number of 1172ddbfc81SArd Biesheuvel * slots of each entry at each iteration, until we have found the entry 1182ddbfc81SArd Biesheuvel * that covers our chosen slot. Use the residual value of target_slot 1192ddbfc81SArd Biesheuvel * to calculate the randomly chosen address, and allocate it directly 1202ddbfc81SArd Biesheuvel * using EFI_ALLOCATE_ADDRESS. 1212ddbfc81SArd Biesheuvel */ 1222ddbfc81SArd Biesheuvel for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { 1232ddbfc81SArd Biesheuvel efi_memory_desc_t *md = (void *)memory_map + map_offset; 1242ddbfc81SArd Biesheuvel efi_physical_addr_t target; 1252ddbfc81SArd Biesheuvel unsigned long pages; 1262ddbfc81SArd Biesheuvel 1272ddbfc81SArd Biesheuvel if (target_slot >= MD_NUM_SLOTS(md)) { 1282ddbfc81SArd Biesheuvel target_slot -= MD_NUM_SLOTS(md); 1292ddbfc81SArd Biesheuvel continue; 1302ddbfc81SArd Biesheuvel } 1312ddbfc81SArd Biesheuvel 1322ddbfc81SArd Biesheuvel target = round_up(md->phys_addr, align) + target_slot * align; 1332ddbfc81SArd Biesheuvel pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE; 1342ddbfc81SArd Biesheuvel 1352ddbfc81SArd Biesheuvel status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, 1362ddbfc81SArd Biesheuvel EFI_LOADER_DATA, pages, &target); 1372ddbfc81SArd Biesheuvel if (status == EFI_SUCCESS) 1382ddbfc81SArd Biesheuvel *addr = target; 1392ddbfc81SArd Biesheuvel break; 1402ddbfc81SArd Biesheuvel } 1412ddbfc81SArd Biesheuvel 1422ddbfc81SArd Biesheuvel efi_call_early(free_pool, memory_map); 1432ddbfc81SArd Biesheuvel 1442ddbfc81SArd Biesheuvel return status; 1452ddbfc81SArd Biesheuvel } 146568bc4e8SArd Biesheuvel 147568bc4e8SArd Biesheuvel #define RANDOM_SEED_SIZE 32 148568bc4e8SArd Biesheuvel 149568bc4e8SArd Biesheuvel efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg) 150568bc4e8SArd Biesheuvel { 151568bc4e8SArd Biesheuvel efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; 152568bc4e8SArd Biesheuvel efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; 153568bc4e8SArd Biesheuvel efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; 154568bc4e8SArd Biesheuvel struct efi_rng_protocol *rng; 155568bc4e8SArd Biesheuvel struct linux_efi_random_seed *seed; 156568bc4e8SArd Biesheuvel efi_status_t status; 157568bc4e8SArd Biesheuvel 158568bc4e8SArd Biesheuvel status = efi_call_early(locate_protocol, &rng_proto, NULL, 159568bc4e8SArd Biesheuvel (void **)&rng); 160568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 161568bc4e8SArd Biesheuvel return status; 162568bc4e8SArd Biesheuvel 163568bc4e8SArd Biesheuvel status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA, 164568bc4e8SArd Biesheuvel sizeof(*seed) + RANDOM_SEED_SIZE, 165568bc4e8SArd Biesheuvel (void **)&seed); 166568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 167568bc4e8SArd Biesheuvel return status; 168568bc4e8SArd Biesheuvel 169568bc4e8SArd Biesheuvel status = rng->get_rng(rng, &rng_algo_raw, RANDOM_SEED_SIZE, 170568bc4e8SArd Biesheuvel seed->bits); 171568bc4e8SArd Biesheuvel if (status == EFI_UNSUPPORTED) 172568bc4e8SArd Biesheuvel /* 173568bc4e8SArd Biesheuvel * Use whatever algorithm we have available if the raw algorithm 174568bc4e8SArd Biesheuvel * is not implemented. 175568bc4e8SArd Biesheuvel */ 176568bc4e8SArd Biesheuvel status = rng->get_rng(rng, NULL, RANDOM_SEED_SIZE, 177568bc4e8SArd Biesheuvel seed->bits); 178568bc4e8SArd Biesheuvel 179568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 180568bc4e8SArd Biesheuvel goto err_freepool; 181568bc4e8SArd Biesheuvel 182568bc4e8SArd Biesheuvel seed->size = RANDOM_SEED_SIZE; 183568bc4e8SArd Biesheuvel status = efi_call_early(install_configuration_table, &rng_table_guid, 184568bc4e8SArd Biesheuvel seed); 185568bc4e8SArd Biesheuvel if (status != EFI_SUCCESS) 186568bc4e8SArd Biesheuvel goto err_freepool; 187568bc4e8SArd Biesheuvel 188568bc4e8SArd Biesheuvel return EFI_SUCCESS; 189568bc4e8SArd Biesheuvel 190568bc4e8SArd Biesheuvel err_freepool: 191568bc4e8SArd Biesheuvel efi_call_early(free_pool, seed); 192568bc4e8SArd Biesheuvel return status; 193568bc4e8SArd Biesheuvel } 194