platform_system_sepolicy/public/lmkd.te
Mark Salyzyn dea7da52c2 lmkd: add live-lock killer daemon
llkd needs the ability to forcibly crash the kernel if
cause is unlikely to result in an orderly shutdown. It
also needs to scan /proc/<pid> for additional process
information.

Test: lmkd_unit_test --gtest_filter=llkd.*
Bug: 33808187
Change-Id: I7f158a13814e79d5ec71fe90dbc7461abb521945
2018-02-05 20:11:46 +00:00

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# lmkd low memory killer daemon
type lmkd, domain, mlstrustedsubject;
type lmkd_exec, exec_type, file_type;
allow lmkd self:global_capability_class_set { dac_override sys_resource kill };
# lmkd locks itself in memory, to prevent it from being
# swapped out and unable to kill other memory hogs.
# system/core commit b28ff9131363f7b4a698990da5748b2a88c3ed35
# b/16236289
allow lmkd self:global_capability_class_set ipc_lock;
## Open and write to /proc/PID/oom_score_adj
## TODO: maybe scope this down?
r_dir_file(lmkd, appdomain)
allow lmkd appdomain:file write;
r_dir_file(lmkd, system_server)
allow lmkd system_server:file write;
## Writes to /sys/module/lowmemorykiller/parameters/minfree
r_dir_file(lmkd, sysfs_lowmemorykiller)
allow lmkd sysfs_lowmemorykiller:file w_file_perms;
# Send kill signals
allow lmkd appdomain:process sigkill;
# Clean up old cgroups
allow lmkd cgroup:dir { remove_name rmdir };
# Allow to read memcg stats
allow lmkd cgroup:file r_file_perms;
# Set self to SCHED_FIFO
allow lmkd self:global_capability_class_set sys_nice;
allow lmkd proc_zoneinfo:file r_file_perms;
# live lock watchdog process allowed to look through /proc/
allow lmkd domain:dir { search open read };
allow lmkd domain:file { open read };
# live lock watchdog process allowed to dump process trace and
# reboot because orderly shutdown may not be possible.
allow lmkd proc_sysrq:file rw_file_perms;
### neverallow rules
# never honor LD_PRELOAD
neverallow * lmkd:process noatsecure;