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Message-ID: <20180612144458.31930370@vmware.local.home>
Date: Tue, 12 Jun 2018 14:44:58 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: "Tobin C. Harding" <me@...in.cc>
Cc: "Theodore Ts'o" <tytso@....edu>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Randy Dunlap <rdunlap@...radead.org>,
Kees Cook <keescook@...omium.org>,
Anna-Maria Gleixner <anna-maria@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 3/4] vsprintf: Use hw RNG for ptr_key
On Tue, 12 Jun 2018 10:39:13 +1000
"Tobin C. Harding" <me@...in.cc> wrote:
> Currently we must wait for enough entropy to become available before
> hashed pointers can be printed. We can remove this wait by using the
> hw RNG if available.
>
> Use hw RNG to get keying material.
>
> Cc: Steven Rostedt (VMware) <rostedt@...dmis.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
-- Steve
> Suggested-by: Kees Cook <keescook@...omium.org>
> Signed-off-by: Tobin C. Harding <me@...in.cc>
> ---
> lib/vsprintf.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index a48aaa79d352..c445f9f28760 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1675,8 +1675,16 @@ static struct random_ready_callback random_ready = {
>
> static int __init initialize_ptr_random(void)
> {
> - int ret = add_random_ready_callback(&random_ready);
> + int key_size = sizeof(ptr_key);
> + int ret;
> +
> + /* Use hw RNG if available */
> + if (get_random_bytes_arch(&ptr_key, key_size) == key_size) {
> + static_branch_disable(¬_filled_random_ptr_key);
> + return 0;
> + }
>
> + ret = add_random_ready_callback(&random_ready);
> if (!ret) {
> return 0;
> } else if (ret == -EALREADY) {
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