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Message-Id: <1527472002-11571-3-git-send-email-me@tobin.cc>
Date: Mon, 28 May 2018 11:46:40 +1000
From: "Tobin C. Harding" <me@...in.cc>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Tobin C. Harding" <me@...in.cc>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Kees Cook <keescook@...omium.org>,
Anna-Maria Gleixner <anna-maria@...utronix.de>,
"Theodore Ts'o" <tytso@....edu>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: [PATCH v6 2/4] random: Return nbytes filled from hw RNG
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 <me@...in.cc>
Acked-by: Theodore Ts'o <tytso@....edu>
Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
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
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