android/android_kernel_samsung_sm8650
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86/hyperv: Block root partition functionality in a Confidential VM

Browse Source 
[ Upstream commit f8acb24aaf89fc46cd953229462ea8abe31b395f ]

Hyper-V should never specify a VM that is a Confidential VM and also
running in the root partition.  Nonetheless, explicitly block such a
combination to guard against a compromised Hyper-V maliciously trying to
exploit root partition functionality in a Confidential VM to expose
Confidential VM secrets. No known bug is being fixed, but the attack
surface for Confidential VMs on Hyper-V is reduced.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1678894453-95392-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Michael Kelley 2023-03-15 08:34:13 -07:00 committed by Greg Kroah-Hartman
parent 5c7648e96d
commit 32aae78314
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/x86/kernel/cpu/mshyperv.c
View File

@ -291,12 +291,16 @@ static void __init ms_hyperv_init_platform(void)
* To mirror what Windows does we should extract CPU management
* features and use the ReservedIdentityBit to detect if Linux is the
* root partition. But that requires negotiating CPU management
* interface (a process to be finalized).
* interface (a process to be finalized). For now, use the privilege
* flag as the indicator for running as root.
*
* For now, use the privilege flag as the indicator for running as
* root.
* Hyper-V should never specify running as root and as a Confidential
* VM. But to protect against a compromised/malicious Hyper-V trying
* to exploit root behavior to expose Confidential VM memory, ignore
* the root partition setting if also a Confidential VM.
*/
if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_CPU_MANAGEMENT) {
if ((ms_hyperv.priv_high & HV_CPU_MANAGEMENT) &&
!(ms_hyperv.priv_high & HV_ISOLATION)) {
hv_root_partition = true;
pr_info("Hyper-V: running as root partition\n");
}