Re: [PATCH] virt-aa-helper: allow common riscv64 loader paths
On Thu, Sep 29, 2022 at 11:30 PM Jim Fehlig <jfehlig(a)suse.com> wrote:
On 9/28/22 06:45, christian.ehrhardt(a)canonical.com wrote:
> From: Christian Ehrhardt <christian.ehrhardt(a)canonical.com>
>
> Riscv64 usually uses u-boot as external -kernel and a loader from
> the open implementation of RISC-V SBI. The paths for those binaries
> as packaged in Debian and Ubuntu are in paths which are usually
> forbidden to be added by the user under /usr/lib...
Do you know if the path is configurable?
Not on the libvirt stage, here it is
a) whatever users specify as kernel/loader in guest XML
b) (our) qemu 7.0 delivers it in the default paths for firmwares (that
are already allowed in src/security/apparmor/libvirt-qemu, but you'd
not want virt-aa-helper to complain on it still)
Are distros free to put those binaries where they choose?
Well, in Debian/Ubuntu we'd still obey the FHS rules, but to some
extent yes it could be in other places.
E.g. /usr/libexec or similar?
The libexec folks are usually fedora/RH which do not care about
apparmor that much, so we have historically not added those in code to
keep it readable (static rules use @libexecdir@ replaced at build
time).
AFAICS you show to copy out the u-boot from the image [1]
Which does not end up in a predictable path-prefix that I could add here.
If you tell me that on Suse the paths for these binaries are different
I'm more than happy to spin a v2 that also has your paths.
Or you provide a follow up with that content once/if you've found a
path that you'll regularly need.
[1]: https://en.opensuse.org/openSUSE:RISC-V
Regards,
Jim
>
> People used to start riscv64 guests only manually via qemu cmdline,
> but trying to encapsulate that via libvirt now causes failures when
> starting the guest due to the apparmor isolation not allowing that:
> virt-aa-helper: error: skipped restricted file
> virt-aa-helper: error: invalid VM definition
>
> Explicitly allow the sub-paths used by u-boot-qemu and opensbi
> under /usr/lib/ as readonly rules.
>
> Signed-off-by: Christian Ehrhardt <christian.ehrhardt(a)canonical.com>
> ---
> src/security/virt-aa-helper.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/src/security/virt-aa-helper.c b/src/security/virt-aa-helper.c
> index f338488da3..ceadaef99b 100644
> --- a/src/security/virt-aa-helper.c
> +++ b/src/security/virt-aa-helper.c
> @@ -476,11 +476,13 @@ valid_path(const char *path, const bool readonly)
> "/initrd",
> "/initrd.img",
> "/usr/share/edk2/",
> - "/usr/share/OVMF/", /* for OVMF images */
> - "/usr/share/ovmf/", /* for OVMF images */
> - "/usr/share/AAVMF/", /* for AAVMF images */
> - "/usr/share/qemu-efi/", /* for AAVMF images */
> - "/usr/share/qemu-efi-aarch64/" /* for AAVMF images */
> + "/usr/share/OVMF/", /* for OVMF images */
> + "/usr/share/ovmf/", /* for OVMF images */
> + "/usr/share/AAVMF/", /* for AAVMF images */
> + "/usr/share/qemu-efi/", /* for AAVMF images */
> + "/usr/share/qemu-efi-aarch64/", /* for AAVMF images */
> + "/usr/lib/u-boot/", /* u-boot loaders for qemu
*/
> + "/usr/lib/riscv64-linux-gnu/opensbi" /* RISC-V SBI implementation
*/
> };
> /* override the above with these */
> const char * const override[] = {
--
Christian Ehrhardt
Senior Staff Engineer, Ubuntu Server
Canonical Ltd