platform_system_sepolicy/public/lmkd.te
Benjamin Gordon 9b2e0cbeea sepolicy: Add rules for non-init namespaces
In kernel 4.7, the capability and capability2 classes were split apart
from cap_userns and cap2_userns (see kernel commit
8e4ff6f228e4722cac74db716e308d1da33d744f). Since then, Android cannot be
run in a container with SELinux in enforcing mode.

This change applies the existing capability rules to user namespaces as
well as the root namespace so that Android running in a container
behaves the same on pre- and post-4.7 kernels.

This is essentially:
  1. New global_capability_class_set and global_capability2_class_set
     that match capability+cap_userns and capability2+cap2_userns,
     respectively.
  2. s/self:capability/self:global_capability_class_set/g
  3. s/self:capability2/self:global_capability2_class_set/g
  4. Add cap_userns and cap2_userns to the existing capability_class_set
     so that it covers all capabilities.  This set was used by several
     neverallow and dontaudit rules, and I confirmed that the new
     classes are still appropriate.

Test: diff new policy against old and confirm that all new rules add
      only cap_userns or cap2_userns;
      Boot ARC++ on a device with the 4.12 kernel.
Bug: crbug.com/754831

Change-Id: I4007eb3a2ecd01b062c4c78d9afee71c530df95f
2017-11-21 08:34:32 -07:00

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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;
### neverallow rules
# never honor LD_PRELOAD
neverallow * lmkd:process noatsecure;