liblog: suppress pmsg on user builds

(cherry pick from commit 7ef5249afa)

- 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
This commit is contained in:
Mark Salyzyn 2016-03-25 15:50:46 -07:00
parent 6267d70b26
commit f58e58a15c
5 changed files with 57 additions and 0 deletions

View File

@ -84,6 +84,7 @@ cc_library {
// $(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",

View File

@ -23,6 +23,7 @@ include $(CLEAR_VARS)
# $(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

View File

@ -259,6 +259,37 @@ LIBLOG_ABI_PUBLIC int __android_log_is_loggable(int prio, const char *tag,
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.

View File

@ -154,6 +154,7 @@ LIBLOG_HIDDEN pid_t __android_log_pid();
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

View File

@ -73,6 +73,11 @@ static int pmsgAvailable(log_id_t logId)
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 @@ static int pmsgAvailable(log_id_t logId)
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 @@ static int pmsgWrite(log_id_t logId, struct timespec *ts,
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;
}