comment

skrev in "TODO" på grejer vi bör kolla på också

lab1/login_linux.c

@@ -2,6 +2,10 @@
 
 /* gcc -std=gnu99 -Wall -g -o mylogin login_linux.c -lcrypt */
 
+/* Note, makepass.c is first used to create hashed password 
+   then, info is manually saved in file passdb */
+
+
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
@@ -12,27 +16,22 @@
 #include <sys/types.h>
 #include <crypt.h>
 #include "pwent.h" /* Step 2 */
+#include <termios.h>
+#include <stdbool.h>
 
 #define TRUE 1
 #define FALSE 0
 #define LENGTH 16
 
 void sighandler() {
-	//sigset_t mask;
-	//sigfillset(&mask);
-	//sigprocmask(SIG_SETMASK, &mask, NULL);
-
 	signal(SIGINT, SIG_IGN); /* This will catch ctrl+c and ignore it*/
-	//signal(SIGTSTP, SIG_IGN); /* This will catch ctrl+z and ignore it*/
-	/* add signalhandling routines here */
-	/* see 'man 2 signal' */
+	signal(SIGTSTP, SIG_IGN); /* This will catch ctrl+z and ignore it*/
 }
 
+
 int main(int argc, char *argv[]) {
 
-	//struct passwd *passwddata /* Step 1 */
-	mypwent *passwddata; /* Step 2 */
-	/* see pwent.h */
+	mypwent *passwddata; 
 
 	char important1[LENGTH] = "**IMPORTANT 1**";
 
@@ -40,9 +39,7 @@ int main(int argc, char *argv[]) {
 
 	char important2[LENGTH] = "**IMPORTANT 2**";
 
-	//char   *c_pass; //you might want to use this variable later...
-	char prompt[] = "password: ";
-	char *user_pass;
+    char user_pass[LENGTH]; 
 
 	sighandler();
 
@@ -53,68 +50,132 @@ int main(int argc, char *argv[]) {
 		printf("Value of variable 'important2' before input of login name: %s\n",
 				important2);
 
+        //////////////////////////////////////////////////////////////////////////////////////////
+        
 		printf("login: ");
 		fflush(NULL); /* Flush all  output buffers */
 		__fpurge(stdin); /* Purge any data in stdin buffer */
 
+        bool okusername = true;
+        /* using fgets instead of gets to avoid buffer overflow attacks*/
 		if (fgets(user,sizeof(user),stdin) == NULL ) {
-			clearerr(stdin); //if EOF only, clear error
-			continue; ///*  overflow attacks.  */
+			clearerr(stdin);
+            okusername = false;
 		}
-		user[strlen(user)-1] = '\0'; //replacing \n with \0
 		
+        if (strlen(user) == sizeof(user)-1 || strlen(user) == 1){
+            // too long username or no username was entered
+            okusername = false;
+        }
+        else{
+            // replacing \n with \0
+            user[strcspn(user,"\n")] = '\0'; 
+		}
+		
+		//////////////////////////////////////////////////////////////////////////////////////////
+        
 		/* check to see if important variable is intact after input of login name - do not remove */
 		printf("Value of variable 'important 1' after input of login name: %*.*s\n",
 				LENGTH - 1, LENGTH - 1, important1);
 		printf("Value of variable 'important 2' after input of login name: %*.*s\n",
 		 		LENGTH - 1, LENGTH - 1, important2);
 
-		// using makepass.c to create hashed password -> saving it manually in passdb
+        //////////////////////////////////////////////////////////////////////////////////////////
+        
+        // using termios instead of the outdated getpass for a more secure program
+        // user_pass = getpass(prompt);
 
-		user_pass = getpass(prompt); //enter password using deprecated function :/
-		passwddata = mygetpwnam(user); //get user info from passdb
+        struct termios old_term_flags, new_term_flags;
 
+        /* Turn echoing off so password will not be shown in terminal */
+        if (tcgetattr(fileno(stdin), &old_term_flags) != 0){
+            perror("Error");
+            exit(EXIT_FAILURE);
+        }
+        new_term_flags = old_term_flags;
+        new_term_flags.c_lflag &= ~ECHO;
+        if (tcsetattr(fileno(stdin), TCSAFLUSH, &new_term_flags) != 0) {
+            perror("Error");
+            exit(EXIT_FAILURE);
+        }
+
+        bool okpassword = true;
+        printf("password: ");
+        if (fgets(user_pass,sizeof(user_pass),stdin) == NULL ) {
+			clearerr(stdin);
+            okpassword = false;
+		}
+        if (strlen(user_pass) == sizeof(user_pass)-1 || strlen(user_pass) == 1){
+            okpassword = false;
+        } 
+
+        /* Restore terminal */
+        if (tcsetattr(fileno(stdin), TCSAFLUSH, &old_term_flags) != 0) {
+            perror("Error");
+			exit(EXIT_FAILURE);
+        }
+        
+        if (!okpassword || !okusername){
+            printf("\nLogin Incorrect \n \n");
+            continue;
+        }
+        user_pass[strcspn(user_pass, "\n")] = '\0'; // replacing \n with \0
+
+        //////////////////////////////////////////////////////////////////////////////////////////
+    
+        // get user info from passdb
+        passwddata = mygetpwnam(user); 
+        
 		if (passwddata != NULL) {
-			/* You have to encrypt user_pass for this to work */
-			/* Don't forget to include the salt */
+            
+            if (passwddata->pwfailed >= 10) {
+				printf("\nToo many failed login attempts. Your account has been locked.\nContact and Admin to unlock your account.\n");
+                continue;
+			}
 			
-
+            /* Encryp user_pass with salt included */
 			char *user_pass_encrypted = crypt(user_pass, passwddata->passwd_salt);
-			if (&user_pass_encrypted == NULL) {
+			if (user_pass_encrypted == NULL) {
 				perror("Error");exit(EXIT_FAILURE);
 			}
-			printf("encryption of typed pass: %s \n", user_pass_encrypted);
-			if (passwddata->pwfailed >= 10) {
-				printf("Too many failed login attempts. Your account has been locked.\nContact and Admin to unlock your account.\n");
-			} else if (!strcmp(user_pass_encrypted, passwddata->passwd)) {
 
-				printf(" You're in !\n");
+            if (!strcmp(user_pass_encrypted, passwddata->passwd)) {
+                // successfull login
+                printf("\n%d failed attemts to login \n",passwddata->pwfailed);
 				passwddata->pwfailed = 0;
 				passwddata->pwage = passwddata->pwage + 1;
-				if (mysetpwent(user, passwddata) < 0) {     /* execute the command  */
+                
+				if (mysetpwent(user, passwddata) < 0) {
 					perror("Error");exit(EXIT_FAILURE);
 				}
-				if (passwddata->pwage > 100) {
-					printf(" Your password is OLD!!!!\n");
+				if (passwddata->pwage > 10) {
+					printf("You need to change your password !\n");
 				} 
 				
-				/*  check UID, see setuid(2) */
 				
-				if (setuid(passwddata->uid) < 0) {     /* execute the command  */
-					perror("Error");exit(EXIT_FAILURE);
+				
+				/*  check UID, see setuid(2) */
+				if (setuid(passwddata->uid) < 0) { //replace this with the ID of the user running the program if you don't have sudo rights
+					perror("Error");
+					exit(EXIT_FAILURE);
 				}
 				/*  start a shell, use execve(2) */
-				if (execve("/bin/bash",NULL,NULL) < 0) {     /* execute the command  */
-					perror("Error");exit(EXIT_FAILURE);
+				if (execve("/bin/bash",NULL,NULL) < 0) {
+					perror("Error");
+					exit(EXIT_FAILURE);
 				}
-			} else {
+				printf("\nWelcome to this system !\n");
+			} 
+			else {
+                // user name exists but password does not match
 				passwddata->pwfailed = passwddata->pwfailed + 1;
-				if (mysetpwent(user, passwddata) < 0) {     /* execute the command  */
-					perror("Error");exit(EXIT_FAILURE);
+				if (mysetpwent(user, passwddata) < 0) { 
+					perror("Error");
+					exit(EXIT_FAILURE);
 				}
 			}
 		}
-		printf("Login Incorrect \n");
+		printf("\nLogin Incorrect \n \n");
 	}
 	return 0;
 }