platform_system_sepolicy/public/runas.te

type runas, domain, domain_deprecated, mlstrustedsubject;
type runas_exec, exec_type, file_type;

allow runas adbd:process sigchld;
allow runas shell:fd use;
allow runas shell:fifo_file { read write };
allow runas devpts:chr_file { read write ioctl };
allow runas shell_data_file:file { read write };

# run-as reads package information.
allow runas system_data_file:file r_file_perms;

# run-as checks and changes to the app data dir.
dontaudit runas self:capability dac_override;
allow runas app_data_file:dir { getattr search };

# run-as switches to the app UID/GID.
allow runas self:capability { setuid setgid };

# run-as switches to the app security context.
selinux_check_context(runas) # validate context
allow runas self:process setcurrent;
allow runas non_system_app_set:process dyntransition; # setcon

###
### neverallow rules
###

# run-as cannot have capabilities other than CAP_SETUID and CAP_SETGID
neverallow runas self:capability ~{ setuid setgid };
neverallow runas self:capability2 *;