1 // SPDX-License-Identifier: GPL-2.0
29  * efi_get_random_bytes() - fill a buffer with random bytes
53  * efi_random_get_seed() - provide random seed as configuration table
70 	struct linux_efi_random_seed *prev_seed, *seed = NULL;  in efi_random_get_seed()  local
88 	 * Check whether a seed was provided by a prior boot stage. In that  in efi_random_get_seed()
91 	 * Note that we should read the seed size with caution, in case the  in efi_random_get_seed()
95 	if (prev_seed && prev_seed->size <= 512U) {  in efi_random_get_seed()
96 		prev_seed_size = prev_seed->size;  in efi_random_get_seed()
102 	 * allocation will survive a kexec reboot (although we refresh the seed  in efi_random_get_seed()
106 			     struct_size(seed, bits, seed_size),  in efi_random_get_seed()
107 			     (void **)&seed);  in efi_random_get_seed()
109 		efi_warn("Failed to allocate memory for RNG seed.\n");  in efi_random_get_seed()
115 					EFI_RANDOM_SEED_SIZE, seed->bits);  in efi_random_get_seed()
123 						EFI_RANDOM_SEED_SIZE, seed->bits);  in efi_random_get_seed()
131 				     &nv_seed_size, seed->bits + offset);  in efi_random_get_seed()
135 			 * We delete the seed here, and /hope/ that this causes  in efi_random_get_seed()
140 			 * instead, and write a new seed.  in efi_random_get_seed()
148 			memzero_explicit(seed->bits + offset, nv_seed_size);  in efi_random_get_seed()
155 		memcpy(seed->bits + offset, prev_seed->bits, prev_seed_size);  in efi_random_get_seed()
159 	seed->size = offset;  in efi_random_get_seed()
160 	status = efi_bs_call(install_configuration_table, &rng_table_guid, seed);  in efi_random_get_seed()
165 		/* wipe and free the old seed if we managed to install the new one */  in efi_random_get_seed()
166 		memzero_explicit(prev_seed->bits, prev_seed_size);  in efi_random_get_seed()
172 	memzero_explicit(seed, struct_size(seed, bits, seed_size));  in efi_random_get_seed()
173 	efi_bs_call(free_pool, seed);  in efi_random_get_seed()
174 	efi_warn("Failed to obtain seed from EFI_RNG_PROTOCOL or EFI variable\n");  in efi_random_get_seed()
177 		efi_warn("Retaining bootloader-supplied seed only");  in efi_random_get_seed()