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

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Date:   Wed,  2 Feb 2022 10:33:55 +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>,
        Marijn Suijten <marijn.suijten@...ainline.org>
Subject: [PATCH 2/2] config: android-recommended: Disable BPF_UNPRIV_DEFAULT_OFF for netd

From: Marijn Suijten <marijns95@...il.com>

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