From patchwork Fri May 8 06:41:30 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephan Mueller X-Patchwork-Id: 6362871 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: X-Original-To: patchwork-linux-crypto@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 79469BEEE1 for ; Fri, 8 May 2015 06:46:16 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6FF1B20108 for ; Fri, 8 May 2015 06:46:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3713B20131 for ; Fri, 8 May 2015 06:46:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752582AbbEHGpu (ORCPT ); Fri, 8 May 2015 02:45:50 -0400 Received: from mail.eperm.de ([89.247.134.16]:34740 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750994AbbEHGol (ORCPT ); Fri, 8 May 2015 02:44:41 -0400 Received: from tachyon.chronox.de (mail.eperm.de [89.247.134.16]) by mail.eperm.de (Postfix) with ESMTPSA id 0AB872A005E; Fri, 8 May 2015 08:44:37 +0200 (CEST) From: Stephan Mueller To: herbert@gondor.apana.org.au Cc: pebolle@tiscali.nl, andreas.steffen@strongswan.org, tytso@mit.edu, sandyinchina@gmail.com, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: [PATCH v5 1/5] random: Async and sync API for accessing nonblocking_pool Date: Fri, 08 May 2015 08:41:30 +0200 Message-ID: <3264123.O3YfJV7UGj@tachyon.chronox.de> User-Agent: KMail/4.14.6 (Linux/3.19.5-200.fc21.x86_64; KDE/4.14.6; x86_64; ; ) In-Reply-To: <1887272.cxqymnQQZn@tachyon.chronox.de> References: <1887272.cxqymnQQZn@tachyon.chronox.de> MIME-Version: 1.0 Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The added API calls provide a synchronous function call get_blocking_random_bytes where the caller is blocked until the nonblocking_pool is initialized. In addition, an asynchronous API call of get_blocking_random_bytes_cb is provided which returns immediately to the caller after submitting the request for random data. The caller-provided buffer that shall be filled with random data is filled up as available entropy permits. The caller may provide a callback function that is invoked once the request is completed. A third API call, get_blocking_random_bytes_cancel, is provided to cancel the random number gathering operation. CC: Andreas Steffen CC: Theodore Ts'o CC: Sandy Harris Signed-off-by: Stephan Mueller --- drivers/char/random.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/random.h | 20 ++++++++++ 2 files changed, 124 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 9cd6968..05faef2 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -407,6 +407,7 @@ static struct poolinfo { static DECLARE_WAIT_QUEUE_HEAD(random_read_wait); static DECLARE_WAIT_QUEUE_HEAD(random_write_wait); static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait); +static DECLARE_WAIT_QUEUE_HEAD(urandom_kernel_wait); static struct fasync_struct *fasync; /********************************************************************** @@ -661,6 +662,7 @@ retry: if (r == &nonblocking_pool) { prandom_reseed_late(); wake_up_interruptible(&urandom_init_wait); + wake_up_interruptible(&urandom_kernel_wait); pr_notice("random: %s pool is initialized\n", r->name); } } @@ -1778,3 +1781,106 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, credit_entropy_bits(poolp, entropy); } EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); + +static bool get_blocking_random_bytes_term(bool *cancel) +{ + if (nonblocking_pool.initialized) + return true; + return *cancel; +} + +/* + * Equivalent function to get_random_bytes with the difference that this + * function blocks the request until the nonblocking_pool is initialized. + * + * This function may sleep. + * + * @buf caller allocated buffer filled with random data + * @nbytes requested number of bytes -- buffer should be at least as big + * @cancel pointer to variable that can be used to cancel the collection + * operation. If this boolean is set to true, the collection operation + * is terminated immediately. When it is set to true during the + * collection loop, the collection is terminated immediately. + */ +void get_blocking_random_bytes(void *buf, int nbytes, bool *cancel) +{ + if (unlikely(nonblocking_pool.initialized == 0)) + wait_event_interruptible(urandom_kernel_wait, + get_blocking_random_bytes_term(cancel)); + + if (!cancel) + extract_entropy(&nonblocking_pool, buf, nbytes, 0, 0); +} +EXPORT_SYMBOL(get_blocking_random_bytes); + +/* + * Immediate canceling the collection operation for the random_work + */ +void get_blocking_random_bytes_cancel(struct random_work *rw) +{ + rw->cancel = true; + wake_up_interruptible(&urandom_kernel_wait); + +} +EXPORT_SYMBOL(get_blocking_random_bytes_cancel); + +static void get_blocking_random_bytes_work(struct work_struct *work) +{ + struct random_work *rw = container_of(work, struct random_work, + rw_work); + + get_blocking_random_bytes(rw->rw_buf, rw->rw_len, &rw->cancel); + if (!rw->cancel) + rw->rw_cb(rw->rw_buf, rw->rw_len, rw->private); +} + +/* + * Asynchronous invocation of the blocking interface. The function + * queues the request in either the private work queue supplied with the + * wq argument or in the general work queue framework if wq is NULL. + * Once the request is completed or upon receiving an error, the callback + * function of cb is called, if not NULL, to inform the caller about the + * completion of its operation. + * + * Only if no work is pending, the pointers for the callback function + * or the output data can be changed. + * + * If a caller wants to cancel the work (e.g. in the module_exit function), + * simply call + * get_blocking_random_bytes_cancel(&my_random_work); + * cancel_work_sync(&my_random_work.rw_work); + * + * @wq pointer to private work queue or NULL - input + * @rw handle to the work queue frame - output + * @buf allocated buffer where random numbers are to be stored + * @nbytes size of buf and implicitly number of bytes requested + * @private pointer to data that is not processed by here, but handed to the + * callback function to allow the caller to maintain a state + * @cb callback function where + * * buf holds the pointer to buf will be supplied + * * buflen holds the length of the gathered random numbers or error code + * of the generation function. + * * private provides a reference to the private data pointer + */ +void get_blocking_random_bytes_cb(struct workqueue_struct *wq, + struct random_work *rw, + u8 *buf, ssize_t nbytes, void *private, + void (*cb)(void *buf, ssize_t buflen, + void *private)) +{ + BUG_ON(!cb); + if (!rw->rw_cb) + INIT_WORK(&rw->rw_work, get_blocking_random_bytes_work); + if (!work_pending(&rw->rw_work)) { + rw->rw_buf = buf; + rw->rw_len = nbytes; + rw->private = private; + rw->rw_cb = cb; + rw->cancel = false; + } + if (wq) + queue_work(wq, &rw->rw_work); + else + schedule_work(&rw->rw_work); +} +EXPORT_SYMBOL(get_blocking_random_bytes_cb); diff --git a/include/linux/random.h b/include/linux/random.h index b05856e..226e8b0 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -7,6 +7,7 @@ #define _LINUX_RANDOM_H #include +#include extern void add_device_randomness(const void *, unsigned int); extern void add_input_randomness(unsigned int type, unsigned int code, @@ -112,4 +113,23 @@ static inline u32 next_pseudo_random32(u32 seed) return seed * 1664525 + 1013904223; } +/* API for asynchronous in-kernel operation */ +struct random_work { + struct work_struct rw_work; + u8 *rw_buf; + ssize_t rw_len; + void *private; + void (*rw_cb)(void *buf, ssize_t buflen, + void *private); + bool cancel; +}; + +void get_blocking_random_bytes(void *buf, int nbytes, bool *cancel); +void get_blocking_random_bytes_cancel(struct random_work *rw); +void get_blocking_random_bytes_cb(struct workqueue_struct *wq, + struct random_work *rw, + u8 *buf, ssize_t nbytes, void *private, + void (*cb)(void *buf, ssize_t buflen, + void *private)); + #endif /* _LINUX_RANDOM_H */