From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZqL8fM9yrh9kPFMAZAXUjH68XGQKYAQN3o23XzlgNjz98FWtonXGHSGsn8HdlD7UMOX+7KQ ARC-Seal: i=1; a=rsa-sha256; t=1526426289; cv=none; d=google.com; s=arc-20160816; b=p8nesmp7B/EjdG3r3B1cUaZqmqkCVilHHHAUabg2Pza1PJJ67sS6JUc/GjvG8+pE72 KtPhEdKyvDAPcLL9OYWQppDizc786FqjZWisR25EiQLlaJBJ+SAaNkPK9OZdFpHTp7oC nlDRbL97C5ORE0J605Nt6gGmK3dl03MK16nP9QbiUTto1JbA9nWws/xEvm60677r3KGW KLcPSWPjGFdgwrHSuPB1Lz+0ppTzd3uY081eT0kRb/AaE2EjqHeOosYAtG9/UfXTRJKg PiIWIbrV98fHNCfx1mX/cfUM1Rx3y77JRDYdAbGAKllYt/FkiQ8u7JbN0FHLfwKSXdZS 5OMg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:dkim-signature:arc-authentication-results; bh=SsO3R7KZpu5pPt/dVnVmaq9kOLQt4PRe1a8Z5O0Xc5g=; b=v0pQw0j9BMlae/2r1yrU3VgzGyPx2pkeYZN+KxAZzUPnYqVQHjGWJbhyYTSnTvreYO MjaCPuTF5KDDhLmIg7WP0uLvrjL+3i25yII3w0mfVCQXGB3bd4cDD2erP6qQn1gSEzEJ 7JGumiFWp22QarAPeQ/wl9Rs9ahCqOYrA8C9jJqhJStZxX9qzqTmgydTNZED3dIRvbtS +wwqDyUFae0nEwIC0BO/qp36bHA4OfLYc/B4yNqwSFWtl/rDJX2u695yTD5NM2PBP0yz pZxlFeuhxOgUF9tUL2t77rWy5BXmx1qISOOAiweCcjwZva/49RUqBtYdHkRq877vJAVI GiYQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@tobin.cc header.s=fm3 header.b=hWRQkgKW; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=ZBT0psKi; spf=neutral (google.com: 66.111.4.26 is neither permitted nor denied by best guess record for domain of me@tobin.cc) smtp.mailfrom=me@tobin.cc Authentication-Results: mx.google.com; dkim=pass header.i=@tobin.cc header.s=fm3 header.b=hWRQkgKW; dkim=pass header.i=@messagingengine.com header.s=fm2 header.b=ZBT0psKi; spf=neutral (google.com: 66.111.4.26 is neither permitted nor denied by best guess record for domain of me@tobin.cc) smtp.mailfrom=me@tobin.cc X-ME-Sender: From: "Tobin C. Harding" To: "Theodore Ts'o" Cc: "Tobin C. Harding" , Linus Torvalds , Randy Dunlap , Steven Rostedt , Kees Cook , Anna-Maria Gleixner , Andrew Morton , Greg Kroah-Hartman , Arnd Bergmann , linux-kernel@vger.kernel.org Subject: [PATCH v5 2/3] random: Return nbytes filled from hw RNG Date: Wed, 16 May 2018 09:17:38 +1000 Message-Id: <1526426259-23012-3-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1526426259-23012-1-git-send-email-me@tobin.cc> References: <1526426259-23012-1-git-send-email-me@tobin.cc> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1600497767242955587?= X-GMAIL-MSGID: =?utf-8?q?1600573973330387411?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Currently the function get_random_bytes_arch() has return value 'void'. If the hw RNG fails we currently fall back to using get_random_bytes(). This defeats the purpose of requesting random material from the hw RNG in the first place. There are currently no intree users of get_random_bytes_arch(). Only get random bytes from the hw RNG, make function return the number of bytes retrieved from the hw RNG. Signed-off-by: Tobin C. Harding Acked-by: Theodore Ts'o Reviewed-by: Steven Rostedt (VMware) --- drivers/char/random.c | 16 +++++++++------- include/linux/random.h | 2 +- 2 files changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 031d18b31e0f..8b9b537ae634 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1725,26 +1725,28 @@ EXPORT_SYMBOL(del_random_ready_callback); * key known by the NSA). So it's useful if we need the speed, but * only if we're willing to trust the hardware manufacturer not to * have put in a back door. + * + * Return number of bytes filled in. */ -void get_random_bytes_arch(void *buf, int nbytes) +int __must_check get_random_bytes_arch(void *buf, int nbytes) { + int left = nbytes; char *p = buf; - trace_get_random_bytes_arch(nbytes, _RET_IP_); - while (nbytes) { + trace_get_random_bytes_arch(left, _RET_IP_); + while (left) { unsigned long v; - int chunk = min(nbytes, (int)sizeof(unsigned long)); + int chunk = min_t(int, left, (int)sizeof(unsigned long)); if (!arch_get_random_long(&v)) break; memcpy(p, &v, chunk); p += chunk; - nbytes -= chunk; + left -= chunk; } - if (nbytes) - get_random_bytes(p, nbytes); + return nbytes - left; } EXPORT_SYMBOL(get_random_bytes_arch); diff --git a/include/linux/random.h b/include/linux/random.h index 2ddf13b4281e..f1c9bc5cd231 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -38,7 +38,7 @@ extern void get_random_bytes(void *buf, int nbytes); extern int wait_for_random_bytes(void); extern int add_random_ready_callback(struct random_ready_callback *rdy); extern void del_random_ready_callback(struct random_ready_callback *rdy); -extern void get_random_bytes_arch(void *buf, int nbytes); +extern int __must_check get_random_bytes_arch(void *buf, int nbytes); #ifndef MODULE extern const struct file_operations random_fops, urandom_fops; -- 2.7.4