diff options
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/Kconfig | 50 | ||||
| -rw-r--r-- | drivers/char/hw_random/virtio-rng.c | 2 | ||||
| -rw-r--r-- | drivers/char/lp.c | 2 | ||||
| -rw-r--r-- | drivers/char/random.c | 45 |
4 files changed, 54 insertions, 45 deletions
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig index 69fd31ffb847..0b6c03643ddc 100644 --- a/drivers/char/Kconfig +++ b/drivers/char/Kconfig @@ -429,28 +429,40 @@ config ADI driver include crash and makedumpfile. config RANDOM_TRUST_CPU - bool "Trust the CPU manufacturer to initialize Linux's CRNG" + bool "Initialize RNG using CPU RNG instructions" + default y depends on ARCH_RANDOM - default n help - Assume that CPU manufacturer (e.g., Intel or AMD for RDSEED or - RDRAND, IBM for the S390 and Power PC architectures) is trustworthy - for the purposes of initializing Linux's CRNG. Since this is not - something that can be independently audited, this amounts to trusting - that CPU manufacturer (perhaps with the insistence or mandate - of a Nation State's intelligence or law enforcement agencies) - has not installed a hidden back door to compromise the CPU's - random number generation facilities. This can also be configured - at boot with "random.trust_cpu=on/off". + Initialize the RNG using random numbers supplied by the CPU's + RNG instructions (e.g. RDRAND), if supported and available. These + random numbers are never used directly, but are rather hashed into + the main input pool, and this happens regardless of whether or not + this option is enabled. Instead, this option controls whether the + they are credited and hence can initialize the RNG. Additionally, + other sources of randomness are always used, regardless of this + setting. Enabling this implies trusting that the CPU can supply high + quality and non-backdoored random numbers. + + Say Y here unless you have reason to mistrust your CPU or believe + its RNG facilities may be faulty. This may also be configured at + boot time with "random.trust_cpu=on/off". config RANDOM_TRUST_BOOTLOADER - bool "Trust the bootloader to initialize Linux's CRNG" - help - Some bootloaders can provide entropy to increase the kernel's initial - device randomness. Say Y here to assume the entropy provided by the - booloader is trustworthy so it will be added to the kernel's entropy - pool. Otherwise, say N here so it will be regarded as device input that - only mixes the entropy pool. This can also be configured at boot with - "random.trust_bootloader=on/off". + bool "Initialize RNG using bootloader-supplied seed" + default y + help + Initialize the RNG using a seed supplied by the bootloader or boot + environment (e.g. EFI or a bootloader-generated device tree). This + seed is not used directly, but is rather hashed into the main input + pool, and this happens regardless of whether or not this option is + enabled. Instead, this option controls whether the seed is credited + and hence can initialize the RNG. Additionally, other sources of + randomness are always used, regardless of this setting. Enabling + this implies trusting that the bootloader can supply high quality and + non-backdoored seeds. + + Say Y here unless you have reason to mistrust your bootloader or + believe its RNG facilities may be faulty. This may also be configured + at boot time with "random.trust_bootloader=on/off". endmenu diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index e856df7e285c..a6f3a8a2aca6 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -159,6 +159,8 @@ static int probe_common(struct virtio_device *vdev) goto err_find; } + virtio_device_ready(vdev); + /* we always have a pending entropy request */ request_entropy(vi); diff --git a/drivers/char/lp.c b/drivers/char/lp.c index 0e22e3b0a04e..38aad99ebb61 100644 --- a/drivers/char/lp.c +++ b/drivers/char/lp.c @@ -1019,7 +1019,7 @@ static struct parport_driver lp_driver = { static int __init lp_init(void) { - int i, err = 0; + int i, err; if (parport_nr[0] == LP_PARPORT_OFF) return 0; diff --git a/drivers/char/random.c b/drivers/char/random.c index b691b9d59503..e3dd1dd3dd22 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -87,7 +87,7 @@ static struct fasync_struct *fasync; /* Control how we warn userspace. */ static struct ratelimit_state urandom_warning = - RATELIMIT_STATE_INIT("warn_urandom_randomness", HZ, 3); + RATELIMIT_STATE_INIT_FLAGS("urandom_warning", HZ, 3, RATELIMIT_MSG_ON_RELEASE); static int ratelimit_disable __read_mostly = IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM); module_param_named(ratelimit_disable, ratelimit_disable, int, 0644); @@ -408,7 +408,7 @@ static ssize_t get_random_bytes_user(struct iov_iter *iter) /* * Immediately overwrite the ChaCha key at index 4 with random - * bytes, in case userspace causes copy_to_user() below to sleep + * bytes, in case userspace causes copy_to_iter() below to sleep * forever, so that we still retain forward secrecy in that case. */ crng_make_state(chacha_state, (u8 *)&chacha_state[4], CHACHA_KEY_SIZE); @@ -650,7 +650,8 @@ static void __cold _credit_init_bits(size_t bits) if (orig < POOL_READY_BITS && new >= POOL_READY_BITS) { crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */ - execute_in_process_context(crng_set_ready, &set_ready); + if (static_key_initialized) + execute_in_process_context(crng_set_ready, &set_ready); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN); pr_notice("crng init done\n"); @@ -724,9 +725,8 @@ static void __cold _credit_init_bits(size_t bits) * **********************************************************************/ -static bool used_arch_random; -static bool trust_cpu __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); -static bool trust_bootloader __ro_after_init = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER); +static bool trust_cpu __initdata = IS_ENABLED(CONFIG_RANDOM_TRUST_CPU); +static bool trust_bootloader __initdata = IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER); static int __init parse_trust_cpu(char *arg) { return kstrtobool(arg, &trust_cpu); @@ -776,7 +776,7 @@ static struct notifier_block pm_notifier = { .notifier_call = random_pm_notifica int __init random_init(const char *command_line) { ktime_t now = ktime_get_real(); - unsigned int i, arch_bytes; + unsigned int i, arch_bits; unsigned long entropy; #if defined(LATENT_ENTROPY_PLUGIN) @@ -784,12 +784,12 @@ int __init random_init(const char *command_line) _mix_pool_bytes(compiletime_seed, sizeof(compiletime_seed)); #endif - for (i = 0, arch_bytes = BLAKE2S_BLOCK_SIZE; + for (i = 0, arch_bits = BLAKE2S_BLOCK_SIZE * 8; i < BLAKE2S_BLOCK_SIZE; i += sizeof(entropy)) { if (!arch_get_random_seed_long_early(&entropy) && !arch_get_random_long_early(&entropy)) { entropy = random_get_entropy(); - arch_bytes -= sizeof(entropy); + arch_bits -= sizeof(entropy) * 8; } _mix_pool_bytes(&entropy, sizeof(entropy)); } @@ -798,11 +798,18 @@ int __init random_init(const char *command_line) _mix_pool_bytes(command_line, strlen(command_line)); add_latent_entropy(); + /* + * If we were initialized by the bootloader before jump labels are + * initialized, then we should enable the static branch here, where + * it's guaranteed that jump labels have been initialized. + */ + if (!static_branch_likely(&crng_is_ready) && crng_init >= CRNG_READY) + crng_set_ready(NULL); + if (crng_ready()) crng_reseed(); else if (trust_cpu) - credit_init_bits(arch_bytes * 8); - used_arch_random = arch_bytes * 8 >= POOL_READY_BITS; + _credit_init_bits(arch_bits); WARN_ON(register_pm_notifier(&pm_notifier)); @@ -812,17 +819,6 @@ int __init random_init(const char *command_line) } /* - * Returns whether arch randomness has been mixed into the initial - * state of the RNG, regardless of whether or not that randomness - * was credited. Knowing this is only good for a very limited set - * of uses, such as early init printk pointer obfuscation. - */ -bool rng_has_arch_random(void) -{ - return used_arch_random; -} - -/* * Add device- or boot-specific data to the input pool to help * initialize it. * @@ -865,13 +861,12 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); * Handle random seed passed by bootloader, and credit it if * CONFIG_RANDOM_TRUST_BOOTLOADER is set. */ -void __cold add_bootloader_randomness(const void *buf, size_t len) +void __init add_bootloader_randomness(const void *buf, size_t len) { mix_pool_bytes(buf, len); if (trust_bootloader) credit_init_bits(len * 8); } -EXPORT_SYMBOL_GPL(add_bootloader_randomness); #if IS_ENABLED(CONFIG_VMGENID) static BLOCKING_NOTIFIER_HEAD(vmfork_chain); @@ -1014,7 +1009,7 @@ void add_interrupt_randomness(int irq) if (new_count & MIX_INFLIGHT) return; - if (new_count < 64 && !time_is_before_jiffies(fast_pool->last + HZ)) + if (new_count < 1024 && !time_is_before_jiffies(fast_pool->last + HZ)) return; if (unlikely(!fast_pool->mix.func)) |