From 021ba8b87e270abdb892ae853fc863cb7e258265 Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Sun, 9 Oct 2022 10:22:39 +0200 Subject: [PATCH 23/25] LRNG - add kernel crypto API interface The LRNG can be registered with the kernel crypto API's random number generator framework. This offers a random number generator with the name "lrng" and a priority that is intended to be higher than the existing RNG implementations. Signed-off-by: Stephan Mueller --- drivers/char/lrng/Kconfig | 26 ++--- drivers/char/lrng/Makefile | 1 + drivers/char/lrng/lrng_interface_kcapi.c | 129 +++++++++++++++++++++++ 3 files changed, 143 insertions(+), 13 deletions(-) create mode 100644 drivers/char/lrng/lrng_interface_kcapi.c --- a/drivers/char/lrng/Kconfig +++ b/drivers/char/lrng/Kconfig @@ -89,18 +89,18 @@ config LRNG_AIS2031_NTG1_SEEDING_STRATEG endmenu # "Specific DRNG seeding strategies" -# menu "LRNG Interfaces" -# -# config LRNG_KCAPI_IF -# tristate "Interface with Kernel Crypto API" -# depends on CRYPTO_RNG -# help -# The LRNG can be registered with the kernel crypto API's -# random number generator framework. This offers a random -# number generator with the name "lrng" and a priority that -# is intended to be higher than the existing RNG -# implementations. -# +menu "LRNG Interfaces" + +config LRNG_KCAPI_IF + tristate "Interface with Kernel Crypto API" + depends on CRYPTO_RNG + help + The LRNG can be registered with the kernel crypto API's + random number generator framework. This offers a random + number generator with the name "lrng" and a priority that + is intended to be higher than the existing RNG + implementations. + # config LRNG_HWRAND_IF # tristate "Interface with Hardware Random Number Generator Framework" # depends on HW_RANDOM @@ -120,7 +120,7 @@ endmenu # "Specific DRNG seeding strateg # identically to /dev/random including IOCTL, read and write # operations. # -# endmenu # "LRNG Interfaces" +endmenu # "LRNG Interfaces" menu "Entropy Source Configuration" --- a/drivers/char/lrng/Makefile +++ b/drivers/char/lrng/Makefile @@ -34,3 +34,4 @@ obj-$(CONFIG_LRNG_COMMON_DEV_IF) += lrng obj-$(CONFIG_LRNG_RANDOM_IF) += lrng_interface_random_user.o \ lrng_interface_random_kernel.o \ lrng_interface_aux.o +obj-$(CONFIG_LRNG_KCAPI_IF) += lrng_interface_kcapi.o --- /dev/null +++ b/drivers/char/lrng/lrng_interface_kcapi.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause +/* + * LRNG interface with the RNG framework of the kernel crypto API + * + * Copyright (C) 2022, Stephan Mueller + */ + +#include +#include +#include + +#include "lrng_drng_mgr.h" +#include "lrng_es_aux.h" + +static int lrng_kcapi_if_init(struct crypto_tfm *tfm) +{ + return 0; +} + +static void lrng_kcapi_if_cleanup(struct crypto_tfm *tfm) { } + +static int lrng_kcapi_if_reseed(const u8 *src, unsigned int slen) +{ + int ret; + + if (!slen) + return 0; + + /* Insert caller-provided data without crediting entropy */ + ret = lrng_pool_insert_aux((u8 *)src, slen, 0); + if (ret) + return ret; + + /* Make sure the new data is immediately available to DRNG */ + lrng_drng_force_reseed(); + + return 0; +} + +static int lrng_kcapi_if_random(struct crypto_rng *tfm, + const u8 *src, unsigned int slen, + u8 *rdata, unsigned int dlen) +{ + int ret = lrng_kcapi_if_reseed(src, slen); + + if (!ret) + lrng_get_random_bytes_full(rdata, dlen); + + return ret; +} + +static int lrng_kcapi_if_reset(struct crypto_rng *tfm, + const u8 *seed, unsigned int slen) +{ + return lrng_kcapi_if_reseed(seed, slen); +} + +static struct rng_alg lrng_alg = { + .generate = lrng_kcapi_if_random, + .seed = lrng_kcapi_if_reset, + .seedsize = 0, + .base = { + .cra_name = "stdrng", + .cra_driver_name = "lrng", + .cra_priority = 500, + .cra_ctxsize = 0, + .cra_module = THIS_MODULE, + .cra_init = lrng_kcapi_if_init, + .cra_exit = lrng_kcapi_if_cleanup, + + } +}; + +#ifdef CONFIG_LRNG_DRNG_ATOMIC +static int lrng_kcapi_if_random_atomic(struct crypto_rng *tfm, + const u8 *src, unsigned int slen, + u8 *rdata, unsigned int dlen) +{ + int ret = lrng_kcapi_if_reseed(src, slen); + + if (!ret) + lrng_get_random_bytes(rdata, dlen); + + return ret; +} + +static struct rng_alg lrng_alg_atomic = { + .generate = lrng_kcapi_if_random_atomic, + .seed = lrng_kcapi_if_reset, + .seedsize = 0, + .base = { + .cra_name = "lrng_atomic", + .cra_driver_name = "lrng_atomic", + .cra_priority = 100, + .cra_ctxsize = 0, + .cra_module = THIS_MODULE, + .cra_init = lrng_kcapi_if_init, + .cra_exit = lrng_kcapi_if_cleanup, + + } +}; +#endif /* CONFIG_LRNG_DRNG_ATOMIC */ + +static int __init lrng_kcapi_if_mod_init(void) +{ + return +#ifdef CONFIG_LRNG_DRNG_ATOMIC + crypto_register_rng(&lrng_alg_atomic) ?: +#endif + crypto_register_rng(&lrng_alg); +} + +static void __exit lrng_kcapi_if_mod_exit(void) +{ + crypto_unregister_rng(&lrng_alg); +#ifdef CONFIG_LRNG_DRNG_ATOMIC + crypto_unregister_rng(&lrng_alg_atomic); +#endif +} + +module_init(lrng_kcapi_if_mod_init); +module_exit(lrng_kcapi_if_mod_exit); + +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_AUTHOR("Stephan Mueller "); +MODULE_DESCRIPTION("Entropy Source and DRNG Manager kernel crypto API RNG framework interface"); +MODULE_ALIAS_CRYPTO("lrng"); +MODULE_ALIAS_CRYPTO("lrng_atomic"); +MODULE_ALIAS_CRYPTO("stdrng");