[apparmor] [PATCH v2] Allow access to sys devices nodes for libnuma

[Ryan Lee]

On Thu, Feb 13, 2025 at 7:58 AM Hector Cao <hector.cao at canonical.com> wrote:
>
> For executables dynamically linked to libnuma, the runtimer linker
> invokes libnuma functions (num_init) that try to access
> /sys/devices/system/node/ and if the application's apparmor
> profile does not allow this access, this access will be denied
> by apparmor with following error message:
>
>   apparmor="DENIED" operation="open" class="file"
>   name="/sys/devices/system/node/" comm="qemu-bridge-hel"
>   requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
>
> Here is the simplified call trace:
>
>   0 ... in ?? () from /lib/x86_64-linux-gnu/libnuma.so.1
>   1 ... in call_init (...) at ./elf/dl-init.c:74
>   2 ... in call_init (...) at ./elf/dl-init.c:120
>   3 _dl_init (...) at ./elf/dl-init.c:121
>   4 ... in _dl_start_user () from /lib64/ld-linux-x86-64.so.2
>
> Allow access to this sysfs folder so that we do not have to
> specify this permission for every executable linked to libnuma

IMO this should go into a dedicated numa abstraction and not be added
to abstractions/base.

>
> Changes in v2:
>   - Fix typo: add missing ending '/' character to the path
>
> Signed-off-by: Hector Cao <hector.cao at canonical.com>
> ---
>  profiles/apparmor.d/abstractions/base | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/profiles/apparmor.d/abstractions/base b/profiles/apparmor.d/abstractions/base
> index bf3f3184e..52cbab920 100644
> --- a/profiles/apparmor.d/abstractions/base
> +++ b/profiles/apparmor.d/abstractions/base
> @@ -108,6 +108,8 @@
>    @{sys}/devices/system/cpu/       r,
>    @{sys}/devices/system/cpu/online r,
>    @{sys}/devices/system/cpu/possible r,
> +  # runtime initialization for binaries linked to libnuma
> +  @{sys}/devices/system/node/     r,
>
>    # transparent hugepage support
>    @{sys}/kernel/mm/transparent_hugepage/hpage_pmd_size r,
> --
> 2.45.2
>
>