liblog: suppress pmsg on user builds
- add optimized & cached LIBLOG_HIDDEN __android_log_is_debuggable()
- check when writing, either LOG_ID_SECURITY, SafetyNet or
debuggable when pushing content to the pmsg buffer.
Bug: 27566046
Change-Id: I85f1b55ec329b38e00f4183836b6ed53046c323d
diff --git a/liblog/Android.bp b/liblog/Android.bp
index 59c696b..302e63c 100644
--- a/liblog/Android.bp
+++ b/liblog/Android.bp
@@ -83,6 +83,7 @@
// $(LOCAL_PATH)/event.logtags)
// so make sure we do not regret hard-coding it as follows:
"-DLIBLOG_LOG_TAG=1005",
+ "-DSNET_EVENT_LOG_TAG=1397638484",
],
compile_multilib: "both",
stl: "none",
diff --git a/liblog/Android.mk b/liblog/Android.mk
index 01c8e77..b24b489 100644
--- a/liblog/Android.mk
+++ b/liblog/Android.mk
@@ -23,6 +23,7 @@
# $(LOCAL_PATH)/event.logtags)
# so make sure we do not regret hard-coding it as follows:
liblog_cflags := -DLIBLOG_LOG_TAG=1005
+liblog_cflags += -DSNET_EVENT_LOG_TAG=1397638484
liblog_sources := log_event_list.c log_event_write.c logger_write.c
liblog_sources += config_write.c logger_name.c logger_lock.c
diff --git a/liblog/log_is_loggable.c b/liblog/log_is_loggable.c
index 551fa76..79a5670 100644
--- a/liblog/log_is_loggable.c
+++ b/liblog/log_is_loggable.c
@@ -259,6 +259,37 @@
return logLevel >= 0 && prio >= logLevel;
}
+LIBLOG_HIDDEN int __android_log_is_debuggable()
+{
+ static uint32_t serial;
+ static struct cache tag_cache;
+ static const char key[] = "ro.debuggable";
+ int ret;
+
+ if (tag_cache.c) { /* ro property does not change after set */
+ ret = tag_cache.c == '1';
+ } else if (lock()) {
+ struct cache temp_cache = { NULL, -1, '\0' };
+ refresh_cache(&temp_cache, key);
+ ret = temp_cache.c == '1';
+ } else {
+ int change_detected = check_cache(&tag_cache);
+ uint32_t current_serial = __system_property_area_serial();
+ if (current_serial != serial) {
+ change_detected = 1;
+ }
+ if (change_detected) {
+ refresh_cache(&tag_cache, key);
+ serial = current_serial;
+ }
+ ret = tag_cache.c == '1';
+
+ unlock();
+ }
+
+ return ret;
+}
+
/*
* For properties that are read often, but generally remain constant.
* Since a change is rare, we will accept a trylock failure gracefully.
diff --git a/liblog/logger.h b/liblog/logger.h
index 5d031d7..c727f29 100644
--- a/liblog/logger.h
+++ b/liblog/logger.h
@@ -154,6 +154,7 @@
LIBLOG_HIDDEN void __android_log_lock();
LIBLOG_HIDDEN int __android_log_trylock();
LIBLOG_HIDDEN void __android_log_unlock();
+LIBLOG_HIDDEN int __android_log_is_debuggable();
__END_DECLS
diff --git a/liblog/pmsg_writer.c b/liblog/pmsg_writer.c
index 7034ceb..9cd3c48 100644
--- a/liblog/pmsg_writer.c
+++ b/liblog/pmsg_writer.c
@@ -73,6 +73,11 @@
if (logId > LOG_ID_SECURITY) {
return -EINVAL;
}
+ if ((logId != LOG_ID_SECURITY) &&
+ (logId != LOG_ID_EVENTS) &&
+ !__android_log_is_debuggable()) {
+ return -EINVAL;
+ }
if (pmsgLoggerWrite.context.fd < 0) {
if (access("/dev/pmsg0", W_OK) == 0) {
return 0;
@@ -82,6 +87,14 @@
return 1;
}
+/*
+ * Extract a 4-byte value from a byte stream.
+ */
+static inline uint32_t get4LE(const uint8_t* src)
+{
+ return src[0] | (src[1] << 8) | (src[2] << 16) | (src[3] << 24);
+}
+
static int pmsgWrite(log_id_t logId, struct timespec *ts,
struct iovec *vec, size_t nr)
{
@@ -92,6 +105,16 @@
size_t i, payloadSize;
ssize_t ret;
+ if ((logId == LOG_ID_EVENTS) && !__android_log_is_debuggable()) {
+ if (vec[0].iov_len < 4) {
+ return -EINVAL;
+ }
+
+ if (SNET_EVENT_LOG_TAG != get4LE(vec[0].iov_base)) {
+ return -EPERM;
+ }
+ }
+
if (pmsgLoggerWrite.context.fd < 0) {
return -EBADF;
}
