From f03dde8549c5b49a84873698a67d103309777bbf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thi=C3=A9baud=20Weksteen?= <tweek@google.com>
Date: Mon, 3 Apr 2023 16:53:12 +1000
Subject: [PATCH] Skip newlines for SELinux logs

libselinux log messages usually end with a new line character. Android
log system does not require the new line character and will include the
character as-is in the log buffer.

This trimming was already implemented when the message is typed as
SELINUX_AVC (see SelinuxAvcLog). Move the truncation one level up so it
is occurring for all types of logs.

Test: boot & adb logcat & inspect SELinux logs
Change-Id: I360359c1b178ef24d555dd41f8d4a18b293a175c
---
 init/selinux.cpp | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/init/selinux.cpp b/init/selinux.cpp
index 062ed3915..907eb80e3 100644
--- a/init/selinux.cpp
+++ b/init/selinux.cpp
@@ -761,15 +761,7 @@ void SelinuxSetEnforcement() {
 
 constexpr size_t kKlogMessageSize = 1024;
 
-void SelinuxAvcLog(char* buf, size_t buf_len) {
-    CHECK_GT(buf_len, 0u);
-
-    size_t str_len = strnlen(buf, buf_len);
-    // trim newline at end of string
-    if (buf[str_len - 1] == '\n') {
-        buf[str_len - 1] = '\0';
-    }
-
+void SelinuxAvcLog(char* buf) {
     struct NetlinkMessage {
         nlmsghdr hdr;
         char buf[kKlogMessageSize];
@@ -835,8 +827,17 @@ int SelinuxKlogCallback(int type, const char* fmt, ...) {
     if (length_written <= 0) {
         return 0;
     }
+
+    // libselinux log messages usually contain a new line character, while
+    // Android LOG() does not expect it. Remove it to avoid empty lines in
+    // the log buffers.
+    size_t str_len = strlen(buf);
+    if (buf[str_len - 1] == '\n') {
+        buf[str_len - 1] = '\0';
+    }
+
     if (type == SELINUX_AVC) {
-        SelinuxAvcLog(buf, sizeof(buf));
+        SelinuxAvcLog(buf);
     } else {
         android::base::KernelLogger(android::base::MAIN, severity, "selinux", nullptr, 0, buf);
     }