Re: [PATCH] host/rootfs: Sandbox Cloud Hypervisor

[Demi Marie Obenour <demiobenour@gmail.com>]

[-- Attachment #1.1.1: Type: text/plain, Size: 2991 bytes --]

On 12/9/25 04:35, Alyssa Ross wrote:
> Demi Marie Obenour <demiobenour@gmail.com> writes:
> 
>> It only needs access to a small number of resources.  Unfortunately, it
>> needs access to /dev/vfio right now.  This should be fixed by using file
>> descriptor passing instead.  Also, Cloud Hypervisor should not run as
>> root.
>>
>> Cloud Hypervisor needs to be able to lock memory.  Running in a user
>> namespace prevents it from using CAP_IPC_LOCK.  Therefore, it is
>> necessary to increase RLIMIT_MLOCK before running Cloud Hypervisor.
>>
>> Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com>
>> ---
>>  host/rootfs/image/usr/bin/run-vmm | 33 ++++++++++++++++++++++++++++++++-
>>  1 file changed, 32 insertions(+), 1 deletion(-)
> 
> Looks good, but it seems to only work for VMs run as s6 services, not
> those run through run-appimage or run-flatpak.  (I suppose the appimage
> integration test is somehow not thorough enough to catch this, which
> should be easier to fix once we understand the problem.)
> 
> bwrap: execvp cloud-hypervisor: No such file or directory
> 
> I suppose this is because etc/login sets PATH to /bin, and we don't
> share /bin with the sandbox.  Changing that to /usr/bin would be a good
> idea I suppose, but would it also be a good idea to share /bin with the
> sandbox?  What do you think?

+1 on sharing /bin and /sbin.

>> diff --git a/host/rootfs/image/usr/bin/run-vmm b/host/rootfs/image/usr/bin/run-vmm
>> index ba8b59c2677408acdd01c2eda3cf2dd60992d881..24c3d607bfcf6fea6196b61d2941141486d33fd6 100755
>> --- a/host/rootfs/image/usr/bin/run-vmm
>> +++ b/host/rootfs/image/usr/bin/run-vmm
>> @@ -52,5 +52,36 @@ unexport !
>>  fdmove -c 3 0
>>  redirfd -r 0 /dev/null
>>  
>> +s6-softlimit -H -l 18446744073709551615
>>  if { udevadm wait /dev/kvm }
>> -cloud-hypervisor --api-socket fd=3
>> +bwrap
>> +  --unshare-all
>> +  --unshare-user
>> +  --dev /dev
>> +  --dev-bind /dev/kvm /dev/kvm
>> +  --dev-bind /dev/vfio /dev/vfio
>> +  --tmpfs /dev/shm
>> +  --tmpfs /tmp
>> +  --tmpfs /var/tmp
>> +  --ro-bind /etc /etc
>> +  --ro-bind /lib /lib
>> +  --ro-bind /nix /nix
>> +  --ro-bind /usr /usr
>> +  --ro-bind /sys /sys
>> +  --bind /run /run
>> +  --proc /proc
>> +  --ro-bind /proc/sys /proc/sys
>> +  --tmpfs /proc/scsi
>> +  --remount-ro /proc/scsi
>> +  --tmpfs /proc/acpi
>> +  --remount-ro /proc/acpi
>> +  --tmpfs /proc/fs
>> +  --remount-ro /proc/fs
>> +  --tmpfs /proc/irq
>> +  --remount-ro /proc/irq
>> +  --ro-bind /dev/null /proc/timer_list
>> +  --ro-bind /dev/null /proc/kcore
>> +  --ro-bind /dev/null /proc/kallsyms
>> +  --ro-bind /dev/null /proc/sysrq-trigger
>> +  --
>> +  cloud-hypervisor --api-socket fd=3
>>
>> ---
>> base-commit: 92e219e7c08c479d216a46d2736ea9d229ff034d
>> change-id: 20251206-b4-sandbox-9be7e5ed9926
>>
>> -- 
>> Sincerely,
>> Demi Marie Obenour (she/her/hers)


-- 
Sincerely,
Demi Marie Obenour (she/her/hers)

[-- Attachment #1.1.2: OpenPGP public key --]
[-- Type: application/pgp-keys, Size: 7253 bytes --]

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 833 bytes --]