linux-kernel - Re: [PATCH 2/2] config: android-recommended: Disable BPF_UNPRIV_DEFAULT

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Date:   Wed, 2 Feb 2022 10:38:58 +0100
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     phone-devel@...r.kernel.org, Rob Herring <robh@...nel.org>
Cc:     Marijn Suijten <marijns95@...il.com>, linux-kernel@...r.kernel.org,
        Amit Pundir <amit.pundir@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [PATCH 2/2] config: android-recommended: Disable
 BPF_UNPRIV_DEFAULT_OFF for netd

On 2022-02-02 10:33:55, Marijn Suijten wrote:
> From: Marijn Suijten <marijns95@...il.com>

Feel free to disregard this `From:` override, didn't catch it when
preparing the patches from a different machine.

- Marijn

> AOSP's `netd` process fails to start on Android S:
> 
>     E ClatdController: getClatEgress4MapFd() failure: Operation not permitted
>     I netd    : Initializing ClatdController: 410us
>     E netd    : Failed to start trafficcontroller: (Status[code: 1, msg: "Pinned map not accessible or does not exist: (/sys/fs/bpf/map_netd_cookie_tag_map): Operation not permitted"])
>     E netd    : CRITICAL: sleeping 60 seconds, netd exiting with failure, crash loop likely!
> 
> And on Android R:
> 
>     I ClatdController: 4.9+ kernel and device shipped with P - clat ebpf might work.
>     E ClatdController: getClatEgressMapFd() failure: Operation not permitted
>     I netd    : Initializing ClatdController: 1409us
>     E netd    : Failed to start trafficcontroller: (Status[code: 1, msg: "Pinned map not accessible or does not exist: (/sys/fs/bpf/map_netd_cookie_tag_map): Operation not permitted"])
> 
> These permission issues are caused by 08389d888287 ("bpf: Add kconfig
> knob for disabling unpriv bpf by default") because AOSP does not provide
> netd the `SYS_ADMIN` capability, and also has no userspace support for
> the `BPF` capability yet.
> 
> Cc: Amit Pundir <amit.pundir@...aro.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Suggested-by: John Stultz <john.stultz@...aro.org>
> [John suggested this in https://linaro.atlassian.net/browse/ACK-107?focusedCommentId=117382]
> Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
> ---
>  kernel/configs/android-recommended.config | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/configs/android-recommended.config b/kernel/configs/android-recommended.config
> index 22bd76e43aca..e400fbbc8aba 100644
> --- a/kernel/configs/android-recommended.config
> +++ b/kernel/configs/android-recommended.config
> @@ -1,4 +1,5 @@
>  #  KEEP ALPHABETICALLY SORTED
> +# CONFIG_BPF_UNPRIV_DEFAULT_OFF is not set
>  # CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
>  # CONFIG_INPUT_MOUSE is not set
>  # CONFIG_LEGACY_PTYS is not set
> -- 
> 2.35.1
>