From mboxrd@z Thu Jan 1 00:00:00 1970 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 73603CCA481 for ; Thu, 23 Jun 2022 16:53:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233639AbiFWQxo (ORCPT ); Thu, 23 Jun 2022 12:53:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52702 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233893AbiFWQvt (ORCPT ); Thu, 23 Jun 2022 12:51:49 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F94317E22; Thu, 23 Jun 2022 09:50:55 -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 sin.source.kernel.org (Postfix) with ESMTPS id BBE35CE25DF; Thu, 23 Jun 2022 16:50:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6AD7C3411B; Thu, 23 Jun 2022 16:50:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1656003052; bh=t6Ud1QmKjHkiufPQ9QUDPoV9gaf9fUOYXmYkqryVvhU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s2tNpm8PhCPVwqgeWepPxuEO14FVrtQfGMveWBZXOR/t8fQLhOjdicdH5mE/IMOy0 WQu7EDvzUg11BQeqqdOdRa2ehrn5HpVAJIjUL2CW6L6FVPxnfmKth5qy3DmXT1BwXD 9hW5KzW7Ovbl8vGXmWzIliRIo7gF4Bc2XDHU4pAo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Eric Biggers , Eric Biggers , Dominik Brodowski , "Jason A. Donenfeld" Subject: [PATCH 4.9 113/264] random: always wake up entropy writers after extraction Date: Thu, 23 Jun 2022 18:41:46 +0200 Message-Id: <20220623164347.266546242@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220623164344.053938039@linuxfoundation.org> References: <20220623164344.053938039@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Jason A. Donenfeld" commit 489c7fc44b5740d377e8cfdbf0851036e493af00 upstream. Now that POOL_BITS == POOL_MIN_BITS, we must unconditionally wake up entropy writers after every extraction. Therefore there's no point of write_wakeup_threshold, so we can move it to the dustbin of unused compatibility sysctls. While we're at it, we can fix a small comparison where we were waking up after <= min rather than < min. Cc: Theodore Ts'o Suggested-by: Eric Biggers Reviewed-by: Eric Biggers Reviewed-by: Dominik Brodowski Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- Documentation/sysctl/kernel.txt | 44 ++++++++++++++++++++++++++++++++++++++-- drivers/char/random.c | 36 ++++++++++++-------------------- 2 files changed, 56 insertions(+), 24 deletions(-) --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -777,9 +777,49 @@ The kernel command line parameter printk a one-time setting until next reboot: once set, it cannot be changed by this sysctl interface anymore. -============================================================== +pty +=== -randomize_va_space: +See Documentation/filesystems/devpts.rst. + + +random +====== + +This is a directory, with the following entries: + +* ``boot_id``: a UUID generated the first time this is retrieved, and + unvarying after that; + +* ``entropy_avail``: the pool's entropy count, in bits; + +* ``poolsize``: the entropy pool size, in bits; + +* ``urandom_min_reseed_secs``: obsolete (used to determine the minimum + number of seconds between urandom pool reseeding). This file is + writable for compatibility purposes, but writing to it has no effect + on any RNG behavior. + +* ``uuid``: a UUID generated every time this is retrieved (this can + thus be used to generate UUIDs at will); + +* ``write_wakeup_threshold``: when the entropy count drops below this + (as a number of bits), processes waiting to write to ``/dev/random`` + are woken up. This file is writable for compatibility purposes, but + writing to it has no effect on any RNG behavior. + +If ``drivers/char/random.c`` is built with ``ADD_INTERRUPT_BENCH`` +defined, these additional entries are present: + +* ``add_interrupt_avg_cycles``: the average number of cycles between + interrupts used to feed the pool; + +* ``add_interrupt_avg_deviation``: the standard deviation seen on the + number of cycles between interrupts used to feed the pool. + + +randomize_va_space +================== This option can be used to select the type of process address space randomization that is used in the system, for architectures --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -297,12 +297,6 @@ enum { */ static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); static struct fasync_struct *fasync; -/* - * If the entropy count falls under this number of bits, then we - * should wake up processes which are selecting or polling on write - * access to /dev/random. - */ -static int random_write_wakeup_bits = POOL_MIN_BITS; static DEFINE_SPINLOCK(random_ready_list_lock); static LIST_HEAD(random_ready_list); @@ -790,10 +784,8 @@ static void crng_reseed(struct crng_stat return; } while (cmpxchg(&input_pool.entropy_count, entropy_count, 0) != entropy_count); extract_entropy(buf.key, sizeof(buf.key)); - if (random_write_wakeup_bits) { - wake_up_interruptible(&random_write_wait); - kill_fasync(&fasync, SIGIO, POLL_OUT); - } + wake_up_interruptible(&random_write_wait); + kill_fasync(&fasync, SIGIO, POLL_OUT); } else { _extract_crng(&primary_crng, buf.block); _crng_backtrack_protect(&primary_crng, buf.block, @@ -1522,7 +1514,7 @@ static unsigned int random_poll(struct f mask = 0; if (crng_ready()) mask |= POLLIN | POLLRDNORM; - if (input_pool.entropy_count < random_write_wakeup_bits) + if (input_pool.entropy_count < POOL_MIN_BITS) mask |= POLLOUT | POLLWRNORM; return mask; } @@ -1607,7 +1599,10 @@ static long random_ioctl(struct file *f, */ if (!capable(CAP_SYS_ADMIN)) return -EPERM; - input_pool.entropy_count = 0; + if (xchg(&input_pool.entropy_count, 0)) { + wake_up_interruptible(&random_write_wait); + kill_fasync(&fasync, SIGIO, POLL_OUT); + } return 0; case RNDRESEEDCRNG: if (!capable(CAP_SYS_ADMIN)) @@ -1682,9 +1677,9 @@ SYSCALL_DEFINE3(getrandom, char __user * #include -static int min_write_thresh; -static int max_write_thresh = POOL_BITS; static int random_min_urandom_seed = 60; +static int random_write_wakeup_bits = POOL_MIN_BITS; +static int sysctl_poolsize = POOL_BITS; static char sysctl_bootid[16]; /* @@ -1723,7 +1718,6 @@ static int proc_do_uuid(struct ctl_table return proc_dostring(&fake_table, write, buffer, lenp, ppos); } -static int sysctl_poolsize = POOL_BITS; extern struct ctl_table random_table[]; struct ctl_table random_table[] = { { @@ -1745,9 +1739,7 @@ struct ctl_table random_table[] = { .data = &random_write_wakeup_bits, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = &min_write_thresh, - .extra2 = &max_write_thresh, + .proc_handler = proc_dointvec, }, { .procname = "urandom_min_reseed_secs", @@ -1928,13 +1920,13 @@ void add_hwgenerator_randomness(const ch } /* Throttle writing if we're above the trickle threshold. - * We'll be woken up again once below random_write_wakeup_thresh, - * when the calling thread is about to terminate, or once - * CRNG_RESEED_INTERVAL has lapsed. + * We'll be woken up again once below POOL_MIN_BITS, when + * the calling thread is about to terminate, or once + * CRNG_RESEED_INTERVAL has elapsed. */ wait_event_interruptible_timeout(random_write_wait, !system_wq || kthread_should_stop() || - input_pool.entropy_count <= random_write_wakeup_bits, + input_pool.entropy_count < POOL_MIN_BITS, CRNG_RESEED_INTERVAL); mix_pool_bytes(buffer, count); credit_entropy_bits(entropy);