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