In the Linux kernel, the following vulnerability has been resolved: x86/coco: Require seeding RNG with RDRAND on CoCo systems There are few uses of CoCo that don't rely on working cryptography and hence a working RNG. Unfortunately, the CoCo threat model means that the VM host cannot be trusted and may actively work against guests to extract secrets or manipulate computation. Since a malicious host can modify or observe nearly all inputs to guests, the only remaining source of entropy for CoCo guests is RDRAND. If RDRAND is broken -- due to CPU hardware fault -- the RNG as a whole is meant to gracefully continue on gathering entropy from other sources, but since there aren't other sources on CoCo, this is catastrophic. This is mostly a concern at boot time when initially seeding the RNG, as after that the consequences of a broken RDRAND are much more theoretical. So, try at boot to seed the RNG using 256 bits of RDRAND output. If this fails, panic(). This will also trigger if the system is booted without RDRAND, as RDRAND is essential for a safe CoCo boot. Add this deliberately to be "just a CoCo x86 driver feature" and not part of the RNG itself. Many device drivers and platforms have some desire to contribute something to the RNG, and add_device_randomness() is specifically meant for this purpose. Any driver can call it with seed data of any quality, or even garbage quality, and it can only possibly make the quality of the RNG better or have no effect, but can never make it worse. Rather than trying to build something into the core of the RNG, consider the particular CoCo issue just a CoCo issue, and therefore separate it all out into driver (well, arch/platform) code. [ bp: Massage commit message. ]
History

Wed, 11 Sep 2024 10:45:00 +0000

Type Values Removed Values Added
First Time appeared Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:9
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat enterprise Linux

Fri, 06 Sep 2024 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_eus:9.2
cpe:/a:redhat:rhel_eus:9.2::nfv
Vendors & Products Redhat
Redhat rhel Eus

cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2024-05-19T08:34:32.767Z

Updated: 2024-11-05T09:24:17.350Z

Reserved: 2024-05-17T13:50:33.110Z

Link: CVE-2024-35875

cve-icon Vulnrichment

Updated: 2024-08-02T03:21:49.026Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-05-19T09:15:08.833

Modified: 2024-11-21T09:21:06.273

Link: CVE-2024-35875

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-05-19T00:00:00Z

Links: CVE-2024-35875 - Bugzilla