From patchwork Fri May 6 21:54:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Jason A. Donenfeld" X-Patchwork-Id: 571102 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4FC83C433F5 for ; Fri, 6 May 2022 21:55:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1444602AbiEFV6z (ORCPT ); Fri, 6 May 2022 17:58:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234286AbiEFV6v (ORCPT ); Fri, 6 May 2022 17:58:51 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D46056FA25; Fri, 6 May 2022 14:55:06 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 84753B8366B; Fri, 6 May 2022 21:55:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC4CDC385A9; Fri, 6 May 2022 21:55:03 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="Pr3GGZvh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1651874101; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=l1+Gz1r+S663SM+LnHF0Br7T7zR5BrwJ05uUG5tXH+g=; b=Pr3GGZvhztrzf1rkg2zjj/GyWlAMWC6hPCAXHwUg+0dAWVIcTSNjYnZuDiVUQecxhdn3m9 Lp+uRJj272AJx48vfSsGrv8ws9NYHp+eUaDmsZqf7coNmE1ZbYtOu97Msk63Qq0Sl/ae/m kQ36My6lHCkimtmcZPfe2+8SL1Gm6A8= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id 37c3fc09 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO); Fri, 6 May 2022 21:55:01 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" Subject: [PATCH 1/3] random: order timer entropy functions below interrupt functions Date: Fri, 6 May 2022 23:54:52 +0200 Message-Id: <20220506215454.1671-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org There are no code changes here; this is just a reordering of functions, so that in subsequent commits, the timer entropy functions can call into the interrupt ones. Signed-off-by: Jason A. Donenfeld --- drivers/char/random.c | 206 +++++++++++++++++++++--------------------- 1 file changed, 103 insertions(+), 103 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 893b8f15fcfe..d15f2133e804 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1011,109 +1011,6 @@ void add_device_randomness(const void *buf, size_t size) } EXPORT_SYMBOL(add_device_randomness); -/* There is one of these per entropy source */ -struct timer_rand_state { - unsigned long last_time; - long last_delta, last_delta2; -}; - -/* - * This function adds entropy to the entropy "pool" by using timing - * delays. It uses the timer_rand_state structure to make an estimate - * of how many bits of entropy this call has added to the pool. - * - * The number "num" is also added to the pool - it should somehow describe - * the type of event which just happened. This is currently 0-255 for - * keyboard scan codes, and 256 upwards for interrupts. - */ -static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) -{ - unsigned long entropy = random_get_entropy(), now = jiffies, flags; - long delta, delta2, delta3; - - spin_lock_irqsave(&input_pool.lock, flags); - _mix_pool_bytes(&entropy, sizeof(entropy)); - _mix_pool_bytes(&num, sizeof(num)); - spin_unlock_irqrestore(&input_pool.lock, flags); - - if (crng_ready()) - return; - - /* - * Calculate number of bits of randomness we probably added. - * We take into account the first, second and third-order deltas - * in order to make our estimate. - */ - delta = now - READ_ONCE(state->last_time); - WRITE_ONCE(state->last_time, now); - - delta2 = delta - READ_ONCE(state->last_delta); - WRITE_ONCE(state->last_delta, delta); - - delta3 = delta2 - READ_ONCE(state->last_delta2); - WRITE_ONCE(state->last_delta2, delta2); - - if (delta < 0) - delta = -delta; - if (delta2 < 0) - delta2 = -delta2; - if (delta3 < 0) - delta3 = -delta3; - if (delta > delta2) - delta = delta2; - if (delta > delta3) - delta = delta3; - - /* - * delta is now minimum absolute delta. - * Round down by 1 bit on general principles, - * and limit entropy estimate to 12 bits. - */ - credit_init_bits(min_t(unsigned int, fls(delta >> 1), 11)); -} - -void add_input_randomness(unsigned int type, unsigned int code, - unsigned int value) -{ - static unsigned char last_value; - static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES }; - - /* Ignore autorepeat and the like. */ - if (value == last_value) - return; - - last_value = value; - add_timer_randomness(&input_timer_state, - (type << 4) ^ code ^ (code >> 4) ^ value); -} -EXPORT_SYMBOL_GPL(add_input_randomness); - -#ifdef CONFIG_BLOCK -void add_disk_randomness(struct gendisk *disk) -{ - if (!disk || !disk->random) - return; - /* First major is 1, so we get >= 0x200 here. */ - add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); -} -EXPORT_SYMBOL_GPL(add_disk_randomness); - -void rand_initialize_disk(struct gendisk *disk) -{ - struct timer_rand_state *state; - - /* - * If kzalloc returns null, we just won't use that entropy - * source. - */ - state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); - if (state) { - state->last_time = INITIAL_JIFFIES; - disk->random = state; - } -} -#endif - /* * Interface for in-kernel drivers of true hardware RNGs. * Those devices may produce endless random bits and will be throttled @@ -1310,6 +1207,109 @@ void add_interrupt_randomness(int irq) } EXPORT_SYMBOL_GPL(add_interrupt_randomness); +/* There is one of these per entropy source */ +struct timer_rand_state { + unsigned long last_time; + long last_delta, last_delta2; +}; + +/* + * This function adds entropy to the entropy "pool" by using timing + * delays. It uses the timer_rand_state structure to make an estimate + * of how many bits of entropy this call has added to the pool. + * + * The number "num" is also added to the pool - it should somehow describe + * the type of event which just happened. This is currently 0-255 for + * keyboard scan codes, and 256 upwards for interrupts. + */ +static void add_timer_randomness(struct timer_rand_state *state, unsigned int num) +{ + unsigned long entropy = random_get_entropy(), now = jiffies, flags; + long delta, delta2, delta3; + + spin_lock_irqsave(&input_pool.lock, flags); + _mix_pool_bytes(&entropy, sizeof(entropy)); + _mix_pool_bytes(&num, sizeof(num)); + spin_unlock_irqrestore(&input_pool.lock, flags); + + if (crng_ready()) + return; + + /* + * Calculate number of bits of randomness we probably added. + * We take into account the first, second and third-order deltas + * in order to make our estimate. + */ + delta = now - READ_ONCE(state->last_time); + WRITE_ONCE(state->last_time, now); + + delta2 = delta - READ_ONCE(state->last_delta); + WRITE_ONCE(state->last_delta, delta); + + delta3 = delta2 - READ_ONCE(state->last_delta2); + WRITE_ONCE(state->last_delta2, delta2); + + if (delta < 0) + delta = -delta; + if (delta2 < 0) + delta2 = -delta2; + if (delta3 < 0) + delta3 = -delta3; + if (delta > delta2) + delta = delta2; + if (delta > delta3) + delta = delta3; + + /* + * delta is now minimum absolute delta. + * Round down by 1 bit on general principles, + * and limit entropy estimate to 12 bits. + */ + credit_init_bits(min_t(unsigned int, fls(delta >> 1), 11)); +} + +void add_input_randomness(unsigned int type, unsigned int code, + unsigned int value) +{ + static unsigned char last_value; + static struct timer_rand_state input_timer_state = { INITIAL_JIFFIES }; + + /* Ignore autorepeat and the like. */ + if (value == last_value) + return; + + last_value = value; + add_timer_randomness(&input_timer_state, + (type << 4) ^ code ^ (code >> 4) ^ value); +} +EXPORT_SYMBOL_GPL(add_input_randomness); + +#ifdef CONFIG_BLOCK +void add_disk_randomness(struct gendisk *disk) +{ + if (!disk || !disk->random) + return; + /* First major is 1, so we get >= 0x200 here. */ + add_timer_randomness(disk->random, 0x100 + disk_devt(disk)); +} +EXPORT_SYMBOL_GPL(add_disk_randomness); + +void rand_initialize_disk(struct gendisk *disk) +{ + struct timer_rand_state *state; + + /* + * If kzalloc returns null, we just won't use that entropy + * source. + */ + state = kzalloc(sizeof(struct timer_rand_state), GFP_KERNEL); + if (state) { + state->last_time = INITIAL_JIFFIES; + disk->random = state; + } +} +#endif + struct entropy_timer_state { unsigned long entropy; struct timer_list timer;