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 8AB3DC433F5 for ; Fri, 27 May 2022 12:02:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352365AbiE0MCw (ORCPT ); Fri, 27 May 2022 08:02:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1352299AbiE0Lxj (ORCPT ); Fri, 27 May 2022 07:53:39 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5DF6E158959; Fri, 27 May 2022 04:47:44 -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 00FC2B824DB; Fri, 27 May 2022 11:47:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 62E1CC385A9; Fri, 27 May 2022 11:47:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1653652061; bh=zRqnFMXIDw2Yu96Nrl9zsNmWv/5/4NOdYhmH9t607/c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eWmA/H9tz34esRs76XFeY+N/tKZyIvVugxzh52Bj7bAv1N9QOBP4R1Inmb6xZrD6y uTYvefknk2pTvKvIFWWoZDgZs6XuSCdtUa11SXLqJk3OrqPwV1IAqfuLqVfK6Dp/2z aUKdU7XkXBy6vWVrVcykrUlnc+SzW0840h25Rwv0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Al Viro , "Jason A. Donenfeld" Subject: [PATCH 5.17 106/111] random: convert to using fops->read_iter() Date: Fri, 27 May 2022 10:50:18 +0200 Message-Id: <20220527084834.270012151@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220527084819.133490171@linuxfoundation.org> References: <20220527084819.133490171@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: Jens Axboe commit 1b388e7765f2eaa137cf5d92b47ef5925ad83ced upstream. This is a pre-requisite to wiring up splice() again for the random and urandom drivers. It also allows us to remove the INT_MAX check in getrandom(), because import_single_range() applies capping internally. Signed-off-by: Jens Axboe [Jason: rewrote get_random_bytes_user() to simplify and also incorporate additional suggestions from Al.] Cc: Al Viro Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- drivers/char/random.c | 66 ++++++++++++++++++++++---------------------------- 1 file changed, 30 insertions(+), 36 deletions(-) --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -52,6 +52,7 @@ #include #include #include +#include #include #include #include @@ -446,13 +447,13 @@ void get_random_bytes(void *buf, size_t } EXPORT_SYMBOL(get_random_bytes); -static ssize_t get_random_bytes_user(void __user *ubuf, size_t len) +static ssize_t get_random_bytes_user(struct iov_iter *iter) { - size_t block_len, left, ret = 0; u32 chacha_state[CHACHA_STATE_WORDS]; - u8 output[CHACHA_BLOCK_SIZE]; + u8 block[CHACHA_BLOCK_SIZE]; + size_t ret = 0, copied; - if (!len) + if (unlikely(!iov_iter_count(iter))) return 0; /* @@ -466,30 +467,22 @@ static ssize_t get_random_bytes_user(voi * use chacha_state after, so we can simply return those bytes to * the user directly. */ - if (len <= CHACHA_KEY_SIZE) { - ret = len - copy_to_user(ubuf, &chacha_state[4], len); + if (iov_iter_count(iter) <= CHACHA_KEY_SIZE) { + ret = copy_to_iter(&chacha_state[4], CHACHA_KEY_SIZE, iter); goto out_zero_chacha; } for (;;) { - chacha20_block(chacha_state, output); + chacha20_block(chacha_state, block); if (unlikely(chacha_state[12] == 0)) ++chacha_state[13]; - block_len = min_t(size_t, len, CHACHA_BLOCK_SIZE); - left = copy_to_user(ubuf, output, block_len); - if (left) { - ret += block_len - left; - break; - } - - ubuf += block_len; - ret += block_len; - len -= block_len; - if (!len) + copied = copy_to_iter(block, sizeof(block), iter); + ret += copied; + if (!iov_iter_count(iter) || copied != sizeof(block)) break; - BUILD_BUG_ON(PAGE_SIZE % CHACHA_BLOCK_SIZE != 0); + BUILD_BUG_ON(PAGE_SIZE % sizeof(block) != 0); if (ret % PAGE_SIZE == 0) { if (signal_pending(current)) break; @@ -497,7 +490,7 @@ static ssize_t get_random_bytes_user(voi } } - memzero_explicit(output, sizeof(output)); + memzero_explicit(block, sizeof(block)); out_zero_chacha: memzero_explicit(chacha_state, sizeof(chacha_state)); return ret ? ret : -EFAULT; @@ -1226,6 +1219,10 @@ static void __cold try_to_generate_entro SYSCALL_DEFINE3(getrandom, char __user *, ubuf, size_t, len, unsigned int, flags) { + struct iov_iter iter; + struct iovec iov; + int ret; + if (flags & ~(GRND_NONBLOCK | GRND_RANDOM | GRND_INSECURE)) return -EINVAL; @@ -1236,19 +1233,18 @@ SYSCALL_DEFINE3(getrandom, char __user * if ((flags & (GRND_INSECURE | GRND_RANDOM)) == (GRND_INSECURE | GRND_RANDOM)) return -EINVAL; - if (len > INT_MAX) - len = INT_MAX; - if (!crng_ready() && !(flags & GRND_INSECURE)) { - int ret; - if (flags & GRND_NONBLOCK) return -EAGAIN; ret = wait_for_random_bytes(); if (unlikely(ret)) return ret; } - return get_random_bytes_user(ubuf, len); + + ret = import_single_range(READ, ubuf, len, &iov, &iter); + if (unlikely(ret)) + return ret; + return get_random_bytes_user(&iter); } static __poll_t random_poll(struct file *file, poll_table *wait) @@ -1292,8 +1288,7 @@ static ssize_t random_write(struct file return (ssize_t)len; } -static ssize_t urandom_read(struct file *file, char __user *ubuf, - size_t len, loff_t *ppos) +static ssize_t urandom_read_iter(struct kiocb *kiocb, struct iov_iter *iter) { static int maxwarn = 10; @@ -1302,23 +1297,22 @@ static ssize_t urandom_read(struct file ++urandom_warning.missed; else if (ratelimit_disable || __ratelimit(&urandom_warning)) { --maxwarn; - pr_notice("%s: uninitialized urandom read (%zd bytes read)\n", - current->comm, len); + pr_notice("%s: uninitialized urandom read (%zu bytes read)\n", + current->comm, iov_iter_count(iter)); } } - return get_random_bytes_user(ubuf, len); + return get_random_bytes_user(iter); } -static ssize_t random_read(struct file *file, char __user *ubuf, - size_t len, loff_t *ppos) +static ssize_t random_read_iter(struct kiocb *kiocb, struct iov_iter *iter) { int ret; ret = wait_for_random_bytes(); if (ret != 0) return ret; - return get_random_bytes_user(ubuf, len); + return get_random_bytes_user(iter); } static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) @@ -1380,7 +1374,7 @@ static int random_fasync(int fd, struct } const struct file_operations random_fops = { - .read = random_read, + .read_iter = random_read_iter, .write = random_write, .poll = random_poll, .unlocked_ioctl = random_ioctl, @@ -1390,7 +1384,7 @@ const struct file_operations random_fops }; const struct file_operations urandom_fops = { - .read = urandom_read, + .read_iter = urandom_read_iter, .write = random_write, .unlocked_ioctl = random_ioctl, .compat_ioctl = compat_ptr_ioctl,