From patchwork Wed Nov 16 16:16:37 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: 625239 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 8109CC4167E for ; Wed, 16 Nov 2022 16:17:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234309AbiKPQRW (ORCPT ); Wed, 16 Nov 2022 11:17:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234848AbiKPQRE (ORCPT ); Wed, 16 Nov 2022 11:17:04 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9DAD057B4F; Wed, 16 Nov 2022 08:17:02 -0800 (PST) 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 507A5B81DD9; Wed, 16 Nov 2022 16:17:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 59EDDC433C1; Wed, 16 Nov 2022 16:16:59 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="mHUvawIZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1668615418; 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: in-reply-to:in-reply-to:references:references; bh=W1wAtKaY05W2lIvCkJNGSoOGC/DQ2aQIlUV6cSqpewY=; b=mHUvawIZManIDNWJYkDAZ1LyUU64eJuoithPe85vkWTE8glRz2J/80l6AjIgn+rpBYe/dW VOFfazhVy5argg5xGDFuAYRISePB5qvxVEFpQgS5cmA6mwErH/Jp9kSSlhm8WpsZv8GEC7 jesrA94tBbgHa+1qpqrzQ0zEQElW6DM= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id b05e0581 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Wed, 16 Nov 2022 16:16:57 +0000 (UTC) From: "Jason A. Donenfeld" To: linux-efi@vger.kernel.org, linux-crypto@vger.kernel.org Cc: "Jason A. Donenfeld" , Ard Biesheuvel , Lennart Poettering Subject: [PATCH RFC v1 1/6] random: add back async readiness notifier Date: Wed, 16 Nov 2022 17:16:37 +0100 Message-Id: <20221116161642.1670235-2-Jason@zx2c4.com> In-Reply-To: <20221116161642.1670235-1-Jason@zx2c4.com> References: <20221116161642.1670235-1-Jason@zx2c4.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org This is required by vsprint, because it can't do things synchronously from hardirq context, and it will be useful for an EFI notifier as well. Signed-off-by: Jason A. Donenfeld --- drivers/char/random.c | 30 ++++++++++++++++++++++++++++++ include/linux/random.h | 1 + 2 files changed, 31 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 6b7aca683b81..b3cad16ec567 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -84,6 +84,8 @@ static DEFINE_STATIC_KEY_FALSE(crng_is_ready); /* Various types of waiters for crng_init->CRNG_READY transition. */ static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); static struct fasync_struct *fasync; +static DEFINE_SPINLOCK(random_ready_chain_lock); +static RAW_NOTIFIER_HEAD(random_ready_chain); /* Control how we warn userspace. */ static struct ratelimit_state urandom_warning = @@ -140,6 +142,33 @@ int wait_for_random_bytes(void) } EXPORT_SYMBOL(wait_for_random_bytes); +/* + * Add a callback function that will be invoked when the crng is initialised, + * or immediately if it already has been. + */ +int __cold notify_on_rng_initialized(struct notifier_block *nb) +{ + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&random_ready_chain_lock, flags); + if (crng_ready()) + nb->notifier_call(nb, 0, NULL); + else + ret = raw_notifier_chain_register(&random_ready_chain, nb); + spin_unlock_irqrestore(&random_ready_chain_lock, flags); + return ret; +} + +static void __cold process_random_ready_list(void) +{ + unsigned long flags; + + spin_lock_irqsave(&random_ready_chain_lock, flags); + raw_notifier_call_chain(&random_ready_chain, 0, NULL); + spin_unlock_irqrestore(&random_ready_chain_lock, flags); +} + #define warn_unseeded_randomness() \ if (IS_ENABLED(CONFIG_WARN_ALL_UNSEEDED_RANDOM) && !crng_ready()) \ printk_deferred(KERN_NOTICE "random: %s called from %pS with crng_init=%d\n", \ @@ -685,6 +714,7 @@ static void __cold _credit_init_bits(size_t bits) crng_reseed(); /* Sets crng_init to CRNG_READY under base_crng.lock. */ if (static_key_initialized) execute_in_process_context(crng_set_ready, &set_ready); + process_random_ready_list(); wake_up_interruptible(&crng_init_wait); kill_fasync(&fasync, SIGIO, POLL_IN); pr_notice("crng init done\n"); diff --git a/include/linux/random.h b/include/linux/random.h index acaa328fb34d..566ffc3ab80d 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -119,6 +119,7 @@ void __init random_init_early(const char *command_line); void __init random_init(void); bool rng_is_initialized(void); int wait_for_random_bytes(void); +int notify_on_rng_initialized(struct notifier_block *nb); /* Calls wait_for_random_bytes() and then calls get_random_bytes(buf, nbytes). * Returns the result of the call to wait_for_random_bytes. */