35795bb50b
Set the user explicitly. Bug: 276813155 Test: boot Change-Id: I57ba99f7b6e80fa74b2fb22fa98b1cb6dc1c18d5
85 lines
4.4 KiB
Text
85 lines
4.4 KiB
Text
# zygote-start is what officially starts netd (see //system/core/rootdir/init.rc)
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# However, on some hardware it's started from post-fs-data as well, which is just
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# a tad earlier. There's no benefit to that though, since on 4.9+ P+ devices netd
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# will just block until bpfloader finishes and sets the bpf.progs_loaded property.
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#
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# It is important that we start bpfloader after:
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# - /sys/fs/bpf is already mounted,
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# - apex (incl. rollback) is initialized (so that in the future we can load bpf
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# programs shipped as part of apex mainline modules)
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# - logd is ready for us to log stuff
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#
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# At the same time we want to be as early as possible to reduce races and thus
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# failures (before memory is fragmented, and cpu is busy running tons of other
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# stuff) and we absolutely want to be before netd and the system boot slot is
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# considered to have booted successfully.
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#
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on load_bpf_programs
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exec_start bpfloader
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service bpfloader /system/bin/bpfloader
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capabilities CHOWN SYS_ADMIN NET_ADMIN
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# The following group memberships are a workaround for lack of DAC_OVERRIDE
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# and allow us to open (among other things) files that we created and are
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# no longer root owned (due to CHOWN) but still have group read access to
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# one of the following groups. This is not perfect, but a more correct
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# solution requires significantly more effort to implement.
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group root graphics network_stack net_admin net_bw_acct net_bw_stats net_raw system
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user root
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#
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# Set RLIMIT_MEMLOCK to 1GiB for bpfloader
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#
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# Actually only 8MiB would be needed if bpfloader ran as its own uid.
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#
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# However, while the rlimit is per-thread, the accounting is system wide.
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# So, for example, if the graphics stack has already allocated 10MiB of
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# memlock data before bpfloader even gets a chance to run, it would fail
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# if its memlock rlimit is only 8MiB - since there would be none left for it.
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#
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# bpfloader succeeding is critical to system health, since a failure will
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# cause netd crashloop and thus system server crashloop... and the only
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# recovery is a full kernel reboot.
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#
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# We've had issues where devices would sometimes (rarely) boot into
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# a crashloop because bpfloader would occasionally lose a boot time
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# race against the graphics stack's boot time locked memory allocation.
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#
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# Thus bpfloader's memlock has to be 8MB higher then the locked memory
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# consumption of the root uid anywhere else in the system...
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# But we don't know what that is for all possible devices...
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#
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# Ideally, we'd simply grant bpfloader the IPC_LOCK capability and it
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# would simply ignore it's memlock rlimit... but it turns that this
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# capability is not even checked by the kernel's bpf system call.
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#
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# As such we simply use 1GiB as a reasonable approximation of infinity.
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#
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rlimit memlock 1073741824 1073741824
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oneshot
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#
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# How to debug bootloops caused by 'bpfloader-failed'.
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#
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# 1. On some lower RAM devices (like wembley) you may need to first enable developer mode
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# (from the Settings app UI), and change the developer option "Logger buffer sizes"
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# from the default (wembley: 64kB) to the maximum (1M) per log buffer.
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# Otherwise buffer will overflow before you manage to dump it and you'll get useless logs.
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#
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# 2. comment out 'reboot_on_failure reboot,bpfloader-failed' below
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# 3. rebuild/reflash/reboot
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# 4. as the device is booting up capture bpfloader logs via:
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# adb logcat -s 'bpfloader:*' 'LibBpfLoader:*'
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#
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# something like:
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# $ adb reboot; sleep 1; adb wait-for-device; adb root; sleep 1; adb wait-for-device; adb logcat -s 'bpfloader:*' 'LibBpfLoader:*'
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# will take care of capturing logs as early as possible
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#
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# 5. look through the logs from the kernel's bpf verifier that bpfloader dumps out,
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# it usually makes sense to search back from the end and find the particular
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# bpf verifier failure that caused bpfloader to terminate early with an error code.
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# This will probably be something along the lines of 'too many jumps' or
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# 'cannot prove return value is 0 or 1' or 'unsupported / unknown operation / helper',
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# 'invalid bpf_context access', etc.
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#
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reboot_on_failure reboot,bpfloader-failed
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# we're not really updatable, but want to be able to load bpf programs shipped in apexes
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updatable
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