diff options
Diffstat (limited to 'drivers/firmware/efi/libstub/random.c')
-rw-r--r-- | drivers/firmware/efi/libstub/random.c | 192 |
1 files changed, 56 insertions, 136 deletions
diff --git a/drivers/firmware/efi/libstub/random.c b/drivers/firmware/efi/libstub/random.c index b4b1d1dcb5fd..24aa37535372 100644 --- a/drivers/firmware/efi/libstub/random.c +++ b/drivers/firmware/efi/libstub/random.c @@ -4,185 +4,105 @@ */ #include <linux/efi.h> -#include <linux/log2.h> #include <asm/efi.h> #include "efistub.h" -struct efi_rng_protocol { - efi_status_t (*get_info)(struct efi_rng_protocol *, - unsigned long *, efi_guid_t *); - efi_status_t (*get_rng)(struct efi_rng_protocol *, - efi_guid_t *, unsigned long, u8 *out); +typedef union efi_rng_protocol efi_rng_protocol_t; + +union efi_rng_protocol { + struct { + efi_status_t (__efiapi *get_info)(efi_rng_protocol_t *, + unsigned long *, + efi_guid_t *); + efi_status_t (__efiapi *get_rng)(efi_rng_protocol_t *, + efi_guid_t *, unsigned long, + u8 *out); + }; + struct { + u32 get_info; + u32 get_rng; + } mixed_mode; }; -efi_status_t efi_get_random_bytes(efi_system_table_t *sys_table_arg, - unsigned long size, u8 *out) +/** + * efi_get_random_bytes() - fill a buffer with random bytes + * @size: size of the buffer + * @out: caller allocated buffer to receive the random bytes + * + * The call will fail if either the firmware does not implement the + * EFI_RNG_PROTOCOL or there are not enough random bytes available to fill + * the buffer. + * + * Return: status code + */ +efi_status_t efi_get_random_bytes(unsigned long size, u8 *out) { efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; efi_status_t status; - struct efi_rng_protocol *rng; + efi_rng_protocol_t *rng = NULL; - status = efi_call_early(locate_protocol, &rng_proto, NULL, - (void **)&rng); + status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); if (status != EFI_SUCCESS) return status; - return rng->get_rng(rng, NULL, size, out); + return efi_call_proto(rng, get_rng, NULL, size, out); } -/* - * Return the number of slots covered by this entry, i.e., the number of - * addresses it covers that are suitably aligned and supply enough room - * for the allocation. +/** + * efi_random_get_seed() - provide random seed as configuration table + * + * The EFI_RNG_PROTOCOL is used to read random bytes. These random bytes are + * saved as a configuration table which can be used as entropy by the kernel + * for the initialization of its pseudo random number generator. + * + * If the EFI_RNG_PROTOCOL is not available or there are not enough random bytes + * available, the configuration table will not be installed and an error code + * will be returned. + * + * Return: status code */ -static unsigned long get_entry_num_slots(efi_memory_desc_t *md, - unsigned long size, - unsigned long align_shift) -{ - unsigned long align = 1UL << align_shift; - u64 first_slot, last_slot, region_end; - - if (md->type != EFI_CONVENTIONAL_MEMORY) - return 0; - - region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1); - - first_slot = round_up(md->phys_addr, align); - last_slot = round_down(region_end - size + 1, align); - - if (first_slot > last_slot) - return 0; - - return ((unsigned long)(last_slot - first_slot) >> align_shift) + 1; -} - -/* - * The UEFI memory descriptors have a virtual address field that is only used - * when installing the virtual mapping using SetVirtualAddressMap(). Since it - * is unused here, we can reuse it to keep track of each descriptor's slot - * count. - */ -#define MD_NUM_SLOTS(md) ((md)->virt_addr) - -efi_status_t efi_random_alloc(efi_system_table_t *sys_table_arg, - unsigned long size, - unsigned long align, - unsigned long *addr, - unsigned long random_seed) -{ - unsigned long map_size, desc_size, total_slots = 0, target_slot; - unsigned long buff_size; - efi_status_t status; - efi_memory_desc_t *memory_map; - int map_offset; - struct efi_boot_memmap map; - - map.map = &memory_map; - map.map_size = &map_size; - map.desc_size = &desc_size; - map.desc_ver = NULL; - map.key_ptr = NULL; - map.buff_size = &buff_size; - - status = efi_get_memory_map(sys_table_arg, &map); - if (status != EFI_SUCCESS) - return status; - - if (align < EFI_ALLOC_ALIGN) - align = EFI_ALLOC_ALIGN; - - /* count the suitable slots in each memory map entry */ - for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { - efi_memory_desc_t *md = (void *)memory_map + map_offset; - unsigned long slots; - - slots = get_entry_num_slots(md, size, ilog2(align)); - MD_NUM_SLOTS(md) = slots; - total_slots += slots; - } - - /* find a random number between 0 and total_slots */ - target_slot = (total_slots * (u16)random_seed) >> 16; - - /* - * target_slot is now a value in the range [0, total_slots), and so - * it corresponds with exactly one of the suitable slots we recorded - * when iterating over the memory map the first time around. - * - * So iterate over the memory map again, subtracting the number of - * slots of each entry at each iteration, until we have found the entry - * that covers our chosen slot. Use the residual value of target_slot - * to calculate the randomly chosen address, and allocate it directly - * using EFI_ALLOCATE_ADDRESS. - */ - for (map_offset = 0; map_offset < map_size; map_offset += desc_size) { - efi_memory_desc_t *md = (void *)memory_map + map_offset; - efi_physical_addr_t target; - unsigned long pages; - - if (target_slot >= MD_NUM_SLOTS(md)) { - target_slot -= MD_NUM_SLOTS(md); - continue; - } - - target = round_up(md->phys_addr, align) + target_slot * align; - pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE; - - status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS, - EFI_LOADER_DATA, pages, &target); - if (status == EFI_SUCCESS) - *addr = target; - break; - } - - efi_call_early(free_pool, memory_map); - - return status; -} - -efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg) +efi_status_t efi_random_get_seed(void) { efi_guid_t rng_proto = EFI_RNG_PROTOCOL_GUID; efi_guid_t rng_algo_raw = EFI_RNG_ALGORITHM_RAW; efi_guid_t rng_table_guid = LINUX_EFI_RANDOM_SEED_TABLE_GUID; - struct efi_rng_protocol *rng; - struct linux_efi_random_seed *seed; + efi_rng_protocol_t *rng = NULL; + struct linux_efi_random_seed *seed = NULL; efi_status_t status; - status = efi_call_early(locate_protocol, &rng_proto, NULL, - (void **)&rng); + status = efi_bs_call(locate_protocol, &rng_proto, NULL, (void **)&rng); if (status != EFI_SUCCESS) return status; - status = efi_call_early(allocate_pool, EFI_RUNTIME_SERVICES_DATA, - sizeof(*seed) + EFI_RANDOM_SEED_SIZE, - (void **)&seed); + status = efi_bs_call(allocate_pool, EFI_RUNTIME_SERVICES_DATA, + sizeof(*seed) + EFI_RANDOM_SEED_SIZE, + (void **)&seed); if (status != EFI_SUCCESS) return status; - status = rng->get_rng(rng, &rng_algo_raw, EFI_RANDOM_SEED_SIZE, - seed->bits); + status = efi_call_proto(rng, get_rng, &rng_algo_raw, + EFI_RANDOM_SEED_SIZE, seed->bits); + if (status == EFI_UNSUPPORTED) /* * Use whatever algorithm we have available if the raw algorithm * is not implemented. */ - status = rng->get_rng(rng, NULL, EFI_RANDOM_SEED_SIZE, - seed->bits); + status = efi_call_proto(rng, get_rng, NULL, + EFI_RANDOM_SEED_SIZE, seed->bits); if (status != EFI_SUCCESS) goto err_freepool; seed->size = EFI_RANDOM_SEED_SIZE; - status = efi_call_early(install_configuration_table, &rng_table_guid, - seed); + status = efi_bs_call(install_configuration_table, &rng_table_guid, seed); if (status != EFI_SUCCESS) goto err_freepool; return EFI_SUCCESS; err_freepool: - efi_call_early(free_pool, seed); + efi_bs_call(free_pool, seed); return status; } |