Hi,

We are working on enabling SELinux for BusyBox.

We found a potential issue below, with suggested patch:


loginutils/login.c::initselinux() should use the selinux seuser for default 
context, not the Linux username.

Patch getseuserbyname() before the get_default_context().


Reference: getseuserbyname on 
https://selinuxproject.org/page/LibselinuxAPISummary

Example code: 
https://github.com/SELinuxProject/selinux/blob/master/libselinux/utils/getseuser.c


-Chang


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diff --git a/loginutils/login.c b/loginutils/login.c
index 25bb5203b..9e41f8a84 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -178,12 +178,16 @@ static void die_if_nologin(void)
 static void initselinux(char *username, char *full_tty,
 						security_context_t *user_sid)
 {
+	char *seuser = NULL, *level = NULL;
 	security_context_t old_tty_sid, new_tty_sid;
 
 	if (!is_selinux_enabled())
 		return;
 
-	if (get_default_context(username, NULL, user_sid)) {
+	if (getseuserbyname(username, &seuser, &level)) {
+		bb_error_msg_and_die("can't get seuser for %s", username);
+	}
+	if (get_default_context(seuser, NULL, user_sid)) {
 		bb_error_msg_and_die("can't get SID for %s", username);
 	}
 	if (getfilecon(full_tty, &old_tty_sid) < 0) {
@@ -196,6 +200,11 @@ static void initselinux(char *username, char *full_tty,
 	if (setfilecon(full_tty, new_tty_sid) != 0) {
 		bb_perror_msg_and_die("chsid(%s, %s) failed", full_tty, new_tty_sid);
 	}
+
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		free(seuser);
+		free(level);
+	}
 }
 #endif
 
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