linux-kernel - Re: [PATCH] x86/coco: Require seeding RNG with RDRAND on CoCo systems

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZccE-LzC3uKyxdGa@tassilo>
Date: Fri, 9 Feb 2024 21:09:12 -0800
From: Andi Kleen <ak@...ux.intel.com>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: x86@...nel.org, linux-coco@...ts.linux.dev,
	linux-kernel@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
	Daniel P . Berrangé <berrange@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Elena Reshetova <elena.reshetova@...el.com>,
	"H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
	Theodore Ts'o <tytso@....edu>, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] x86/coco: Require seeding RNG with RDRAND on CoCo systems


> +	for (i = 0; i < ARRAY_SIZE(rng_seed); i += longs) {
> +		longs = arch_get_random_longs(&rng_seed[i], ARRAY_SIZE(rng_seed) - i);
> +
> +		/*
> +		 * A zero return value means that the guest is under attack,
> +		 * the hardware is broken, or some other mishap has occurred
> +		 * that means the RNG cannot be properly rng_seeded, which also
> +		 * likely means most crypto inside of the CoCo instance will be
> +		 * broken, defeating the purpose of CoCo in the first place. So
> +		 * just panic here because it's absolutely unsafe to continue
> +		 * executing.
> +		 */
> +		BUG_ON(longs == 0);

BUG_ON doesn't necessarily panic. If you want panic, use panic.

-Andi