skeud

commit: cc0ce1f88dde3153ce506edd17370296b799e101
parent ad5eda7959bcf348aba69f972b493e063fd3a6f5
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Tue,  1 Nov 2022 17:43:59 +0100

su: Fix getting the username

Diffstat:
M
su.c
60
+++++++++++++++++++++++++-----------------------------------

1 file changed, 25 insertions(+), 35 deletions(-)
diff --git a/su.c b/su.c
@@ -30,7 +30,7 @@ main(int argc, char *argv[])
 	bool opt_l           = false;
 	bool opt_p           = false;
 	int c                = EOF;
-	char *username       = NULL;
+	char *username       = "root";
 	struct passwd *pwent = NULL;
 	char *shell          = NULL;
 	char *command        = NULL;
@@ -76,16 +76,19 @@ main(int argc, char *argv[])
 
 	if(argv[0] && strcmp(argv[0], "-") == 0)
 	{
-		if(argc < 2)
+		opt_l = true;
+
+		if(argc >= 2)
 		{
-			fprintf(stderr, "su: Option - requires an operand\n");
-			return 1;
+			username = argv[1];
+			argc -= 2;
+			argv += 2;
+		}
+		else
+		{
+			argc -= 1;
+			argv += 1;
 		}
-
-		opt_l    = true;
-		username = argv[1];
-		argc -= 2;
-		argv += 2;
 	}
 
 	if((opt_l && argc > 0) || argc > 1)
@@ -99,18 +102,16 @@ main(int argc, char *argv[])
 		username = argv[0];
 	}
 
-	if(username != NULL)
-	{
-		errno = 0;
-		pwent = getpwnam(username);
+	errno = 0;
+	pwent = getpwnam(username);
 
-		if(errno != 0)
-		{
-			perror("getpwnam");
-			return 1;
-		}
+	if(errno != 0)
+	{
+		perror("su: getpwnam");
+		return 1;
 	}
 
+	fprintf(stderr, "su: Authenticating as %s\n", username);
 	if(getuid() != 0)
 	{
 		char *pw_hash = NULL;
@@ -159,15 +160,13 @@ main(int argc, char *argv[])
 
 	if(pwent != NULL)
 	{
-		assert(username != NULL);
-
 		if(setgid(pwent->pw_gid) < 0)
 		{
-			perror("setgid");
+			perror("su: setgid");
 		}
 		if(setuid(pwent->pw_uid) < 0)
 		{
-			perror("setuid");
+			perror("su: setuid");
 		}
 
 		if(pwent->pw_shell != NULL)
@@ -179,9 +178,9 @@ main(int argc, char *argv[])
 		{
 			setenv("HOME", pwent->pw_dir, 1);
 
-			if(!opt_l && (chdir(pwent->pw_dir) != 0))
+			if(opt_l)
 			{
-				perror("chdir");
+				if(chdir(pwent->pw_dir) != 0) perror("su: chdir");
 			}
 		}
 
@@ -200,17 +199,8 @@ main(int argc, char *argv[])
 		shell = "/bin/sh";
 	}
 
-	if(username != NULL)
-	{
-		setenv("USER", username, 1);
-		setenv("LOGNAME", username, 1);
-	}
-	else
-	{
-		setenv("USER", "root", 1);
-		setenv("LOGNAME", "root", 1);
-	}
-
+	setenv("USER", username, 1);
+	setenv("LOGNAME", username, 1);
 	setenv("SHELL", shell, 1);
 	setenv("IFS", " \t\n", 1);