android_system_sepolicy/private/shell.te
Ryan Savitski ffa0dd93f3 perf_event: rules for system and simpleperf domain
This patch adds the necessary rules to support the existing usage of
perf_event_open by the system partition, which almost exclusively
concerns the simpleperf profiler. A new domain is introduced for some
(but not all) executions of the system image simpleperf. The following
configurations are supported:
* shell -> shell process (no domain transition)
* shell -> debuggable app (through shell -> runas -> runas_app)
* shell -> profileable app (through shell -> simpleperf_app_runner ->
                            untrusted_app -> simpleperf)
* debuggable/profile app -> self (through untrusted_app -> simpleperf)

simpleperf_app_runner still enters the untrusted_app domain immediately
before exec to properly inherit the categories related to MLS. My
understanding is that a direct transition would require modifying
external/selinux and seapp_contexts as with "fromRunAs", which seems
unnecessarily complex for this case.

runas_app can still run side-loaded binaries and use perf_event_open,
but it checks that the target app is exactly "debuggable"
(profileability is insufficient).

system-wide profiling is effectively constrained to "su" on debug
builds.

See go/perf-event-open-security for a more detailed explanation of the
scenarios covered here.

Tested: "atest CtsSimpleperfTestCases" on crosshatch-user/userdebug
Tested: manual simpleperf invocations on crosshatch-userdebug
Bug: 137092007
Change-Id: I2100929bae6d81f336f72eff4235fd5a78b94066
2020-01-15 16:56:41 +00:00

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typeattribute shell coredomain;
# allow shell input injection
allow shell uhid_device:chr_file rw_file_perms;
# systrace support - allow atrace to run
allow shell debugfs_tracing_debug:dir r_dir_perms;
allow shell debugfs_tracing:dir r_dir_perms;
allow shell debugfs_tracing:file rw_file_perms;
allow shell debugfs_trace_marker:file getattr;
allow shell atrace_exec:file rx_file_perms;
userdebug_or_eng(`
allow shell debugfs_tracing_debug:file rw_file_perms;
')
# read config.gz for CTS purposes
allow shell config_gz:file r_file_perms;
# Run app_process.
# XXX Transition into its own domain?
app_domain(shell)
# allow shell to call dumpsys storaged
binder_call(shell, storaged)
# Perform SELinux access checks, needed for CTS
selinux_check_access(shell)
selinux_check_context(shell)
# Control Perfetto traced and obtain traces from it.
# Needed for Studio and debugging.
unix_socket_connect(shell, traced_consumer, traced)
# Allow shell binaries to write trace data to Perfetto. Used for testing and
# cmdline utils.
perfetto_producer(shell)
domain_auto_trans(shell, vendor_shell_exec, vendor_shell)
# Allow shell binaries to exec the perfetto cmdline util and have that
# transition into its own domain, so that it behaves consistently to
# when exec()-d by statsd.
domain_auto_trans(shell, perfetto_exec, perfetto)
# Allow to send SIGINT to perfetto when daemonized.
allow shell perfetto:process signal;
# Allow shell to run adb shell cmd stats commands. Needed for CTS.
binder_call(shell, statsd);
# Allow shell to read and unlink traces stored in /data/misc/perfetto-traces.
allow shell perfetto_traces_data_file:dir rw_dir_perms;
allow shell perfetto_traces_data_file:file { r_file_perms unlink };
# Allow shell to run adb shell cmd gpu commands.
binder_call(shell, gpuservice);
# Allow shell to use atrace HAL
hal_client_domain(shell, hal_atrace)
# For hostside tests such as CTS listening ports test.
allow shell proc_net_tcp_udp:file r_file_perms;
# The dl.exec_linker* tests need to execute /system/bin/linker
# b/124789393
allow shell system_linker_exec:file rx_file_perms;
# Renderscript host side tests depend on being able to execute
# /system/bin/bcc (b/126388046)
allow shell rs_exec:file rx_file_perms;
# Allow shell to start and comminicate with lpdumpd.
set_prop(shell, lpdumpd_prop);
binder_call(shell, lpdumpd)
# Allow shell to set linker property
userdebug_or_eng(`
set_prop(shell, linker_prop)
')
# Allow shell to get encryption policy of /data/local/tmp/, for CTS
allowxperm shell shell_data_file:dir ioctl {
FS_IOC_GET_ENCRYPTION_POLICY
FS_IOC_GET_ENCRYPTION_POLICY_EX
};
# Allow shell to execute simpleperf without a domain transition.
allow shell simpleperf_exec:file rx_file_perms;
# Allow shell to call perf_event_open for profiling other shell processes, but
# not the whole system.
allow shell self:perf_event { open read write kernel };
neverallow shell self:perf_event ~{ open read write kernel };