login: make it saner and smaller by ~0.5k.

1 files changed, 131 insertions, 185 deletions

diff --git a/loginutils/login.c b/loginutils/login.c
index c05ec066a..19f865550 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -29,59 +29,59 @@
 
 #ifdef CONFIG_FEATURE_UTMP
 // import from utmp.c
-static void checkutmp(int picky);
-static void setutmp(const char *name, const char *line);
-/* Stuff global to this file */
 static struct utmp utent;
+static void read_or_build_utent(int picky);
+static void write_utent(const char *username);
 #endif
 
 enum {
         TIMEOUT = 60,
         EMPTY_USERNAME_COUNT = 10,
         USERNAME_SIZE = 32,
+        TTYNAME_SIZE = 32,
 };
 
-static int check_nologin(int amroot);
+static void die_if_nologin_and_non_root(int amroot);
 
 #if defined CONFIG_FEATURE_SECURETTY
-static int check_tty(const char *tty);
+static int check_securetty(void);
 
 #else
-static inline int check_tty(const char *tty) { return 1; }
+static inline int check_securetty(void) { return 1; }
 
 #endif
 
-static int is_my_tty(const char *tty);
-static int login_prompt(char *buf_name);
+static int is_my_tty(void);
+static void get_username_or_die(char *buf, int size_buf);
 static void motd(void);
 
 
 static void alarm_handler(int sig ATTRIBUTE_UNUSED)
 {
-        fprintf(stderr, "\r\nLogin timed out after %s seconds\r\n", TIMEOUT);
+        fprintf(stderr, "\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
         exit(EXIT_SUCCESS);
 }
 
 
+static char full_tty[TTYNAME_SIZE];
+static char* short_tty = full_tty;
+
+
 int login_main(int argc, char **argv)
 {
-        char tty[BUFSIZ];
-        char full_tty[200];
         char fromhost[512];
         char username[USERNAME_SIZE];
         const char *tmp;
         int amroot;
         int flag;
-        int failed;
         int count = 0;
-        struct passwd *pw, pw_copy;
+        struct passwd *pw;
 #ifdef CONFIG_WHEEL_GROUP
         struct group *grp;
 #endif
         int opt_preserve = 0;
         int opt_fflag = 0;
         char *opt_host = 0;
-        int alarmstarted = 0;
 #ifdef CONFIG_SELINUX
         security_context_t user_sid = NULL;
 #endif
@@ -90,7 +90,6 @@ int login_main(int argc, char **argv)
         amroot = (getuid() == 0);
         signal(SIGALRM, alarm_handler);
         alarm(TIMEOUT);
-        alarmstarted = 1;
 
         while ((flag = getopt(argc, argv, "f:h:p")) != EOF) {
                 switch (flag) {
@@ -105,10 +104,10 @@ int login_main(int argc, char **argv)
                         if (optarg != argv[optind-1])
                                 bb_show_usage();
 
-                        if (!amroot)            /* Auth bypass only if real UID is zero */
-                                bb_error_msg_and_die("-f permission denied");
+                        if (!amroot)    /* Auth bypass only if real UID is zero */
+                                bb_error_msg_and_die("-f is for root only");
 
-                        safe_strncpy(username, optarg, USERNAME_SIZE);
+                        safe_strncpy(username, optarg, sizeof(username));
                         opt_fflag = 1;
                         break;
                 case 'h':
@@ -118,113 +117,83 @@ int login_main(int argc, char **argv)
                         bb_show_usage();
                 }
         }
-
         if (optind < argc)             /* user from command line (getty) */
-                safe_strncpy(username, argv[optind], USERNAME_SIZE);
+                safe_strncpy(username, argv[optind], sizeof(username));
 
+        /* Let's find out and memorize our tty */
         if (!isatty(0) || !isatty(1) || !isatty(2))
                 return EXIT_FAILURE;            /* Must be a terminal */
-
-#ifdef CONFIG_FEATURE_UTMP
-        checkutmp(!amroot);
-#endif
-
+        safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty));
         tmp = ttyname(0);
-        if (tmp && (strncmp(tmp, "/dev/", 5) == 0))
-                safe_strncpy(tty, tmp + 5, sizeof(tty));
-        else if (tmp && *tmp == '/')
-                safe_strncpy(tty, tmp, sizeof(tty));
-        else
-                safe_strncpy(tty, "UNKNOWN", sizeof(tty));
+        if (tmp) {
+                safe_strncpy(full_tty, tmp, sizeof(full_tty));
+                if (strncmp(full_tty, "/dev/", 5) == 0)
+                        short_tty = full_tty + 5;
+        }
 
-#ifdef CONFIG_FEATURE_UTMP
-        if (amroot)
-                memset(utent.ut_host, 0, sizeof(utent.ut_host));
-#endif
+        if (ENABLE_FEATURE_UTMP) {
+                read_or_build_utent(!amroot);
+                if (amroot)
+                        memset(utent.ut_host, 0, sizeof(utent.ut_host));
+        }
 
         if (opt_host) {
-#ifdef CONFIG_FEATURE_UTMP
-                safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
-#endif
+                if (ENABLE_FEATURE_UTMP)
+                        safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
                 snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s' from "
-                                        "`%.200s'", tty, opt_host);
+                                        "`%.200s'", short_tty, opt_host);
         }
         else
-                snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s'", tty);
+                snprintf(fromhost, sizeof(fromhost)-1, " on `%.100s'", short_tty);
 
         bb_setpgrp;
 
         openlog(bb_applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
 
         while (1) {
-                failed = 0;
-
                 if (!username[0])
-                        if (!login_prompt(username))
-                                return EXIT_FAILURE;
-
-                if (!alarmstarted && (TIMEOUT > 0)) {
-                        alarm(TIMEOUT);
-                        alarmstarted = 1;
-                }
+                        get_username_or_die(username, sizeof(username));
 
                 pw = getpwnam(username);
                 if (!pw) {
-                        pw_copy.pw_name   = "UNKNOWN";
-                        pw_copy.pw_passwd = "!";
-                        opt_fflag = 0;
-                        failed = 1;
-                } else
-                        pw_copy = *pw;
-
-                pw = &pw_copy;
+                        safe_strncpy(username, "UNKNOWN", sizeof(username));
+                        goto auth_failed;
+                }
 
-                if ((pw->pw_passwd[0] == '!') || (pw->pw_passwd[0] == '*'))
-                        failed = 1;
+                if (pw->pw_passwd[0] == '!' || pw->pw_passwd[0] == '*')
+                        goto auth_failed;
 
-                if (opt_fflag) {
-                        opt_fflag = 0;
-                        goto auth_ok;
-                }
+                if (opt_fflag)
+                        break; /* -f USER: success without asking passwd */
 
-                if (!failed && (pw->pw_uid == 0) && (!check_tty(tty)))
-                        failed = 1;
+                if (pw->pw_uid == 0 && !check_securetty())
+                        goto auth_failed;
 
                 /* Don't check the password if password entry is empty (!) */
                 if (!pw->pw_passwd[0])
-                        goto auth_ok;
+                        break; 
 
                 /* authorization takes place here */
                 if (correct_password(pw))
-                        goto auth_ok;
-
-                failed = 1;
-
-auth_ok:
-                if (!failed)
-                        break;
+                        break; 
 
+auth_failed:
+                opt_fflag = 0;
                 bb_do_delay(FAIL_DELAY);
                 puts("Login incorrect");
-                username[0] = 0;
                 if (++count == 3) {
-                        syslog(LOG_WARNING, "invalid password for `%s'%s", pw->pw_name, fromhost);
+                        syslog(LOG_WARNING, "invalid password for `%s'%s",
+                                                username, fromhost);
                         return EXIT_FAILURE;
                 }
+                username[0] = '\0';
         }
 
         alarm(0);
-        if (check_nologin(pw->pw_uid == 0))
-                return EXIT_FAILURE;
-
-#ifdef CONFIG_FEATURE_UTMP
-        setutmp(username, tty);
-#endif
+        die_if_nologin_and_non_root(pw->pw_uid == 0);
 
-        if (*tty != '/')
-                snprintf(full_tty, sizeof(full_tty)-1, "/dev/%s", tty);
-        else
-                safe_strncpy(full_tty, tty, sizeof(full_tty)-1);
+        if (ENABLE_FEATURE_UTMP)
+                write_utent(username);
 
 #ifdef CONFIG_SELINUX
         if (is_selinux_enabled()) {
@@ -249,7 +218,7 @@ auth_ok:
                 }
         }
 #endif
-        if (!is_my_tty(full_tty))
+        if (!is_my_tty())
                 syslog(LOG_ERR, "unable to determine TTY name, got %s", full_tty);
 
         /* Try these, but don't complain if they fail
@@ -300,96 +269,91 @@ auth_ok:
 }
 
 
-static int login_prompt(char *buf_name)
+static void get_username_or_die(char *buf, int size_buf)
 {
-        char buf[1024];
-        char *sp, *ep;
-        int i;
-
-        for (i=0; i<EMPTY_USERNAME_COUNT; i++) {
-                print_login_prompt();
-
-                if (!fgets(buf, sizeof(buf)-1, stdin))
-                        return 0;
-
-                if (!strchr(buf, '\n'))
-                        return 0;
-
-                for (sp = buf; isspace(*sp); sp++) { }
-                for (ep = sp; isgraph(*ep); ep++) { }
-
-                *ep = '\0';
-                safe_strncpy(buf_name, sp, USERNAME_SIZE);
-                if (buf_name[0])
-                        return 1;
-        }
-        return 0;
+        int c, cntdown;
+        cntdown = EMPTY_USERNAME_COUNT;
+prompt:
+        /* skip whitespace */
+        print_login_prompt();
+        do {
+                c = getchar();
+                if (c == EOF) exit(1);
+                if (c == '\n') {
+                        if (!--cntdown) exit(1);
+                        goto prompt;
+                }
+        } while (isspace(c));
+
+        *buf++ = c;
+        if (!fgets(buf, size_buf-2, stdin))
+                exit(1);
+        if (!strchr(buf, '\n'))
+                exit(1);
+        while (isgraph(*buf)) buf++;
+        *buf = '\0';
 }
 
 
-static int check_nologin(int amroot)
+static void die_if_nologin_and_non_root(int amroot)
 {
-        if (access(bb_path_nologin_file, F_OK) == 0) {
-                FILE *fp;
-                int c;
-
-                fp = fopen(bb_path_nologin_file, "r");
-                if (fp) {
-                        while ((c = getc(fp)) != EOF)
-                                putchar((c=='\n') ? '\r' : c);
+        FILE *fp;
+        int c;
 
-                        fflush(stdout);
-                        fclose(fp);
-                } else {
-                        puts("\r\nSystem closed for routine maintenance.\r");
-                }
-                if (!amroot)
-                        return 1;
+        if (access(bb_path_nologin_file, F_OK))
+                return;
 
-                puts("\r\n[Disconnect bypassed -- root login allowed.]\r");
-        }
-        return 0;
+        fp = fopen(bb_path_nologin_file, "r");
+        if (fp) {
+                while ((c = getc(fp)) != EOF)
+                        putchar((c=='\n') ? '\r' : c);
+                fflush(stdout);
+                fclose(fp);
+        } else
+                puts("\r\nSystem closed for routine maintenance\r");
+        if (!amroot)
+                exit(1);
+        puts("\r\n[Disconnect bypassed -- root login allowed.]\r");
 }
 
 #ifdef CONFIG_FEATURE_SECURETTY
 
-static int check_tty(const char *tty)
+static int check_securetty(void)
 {
         FILE *fp;
         int i;
         char buf[BUFSIZ];
 
         fp = fopen(bb_path_securetty_file, "r");
-        if (fp) {
-                while (fgets(buf, sizeof(buf)-1, fp)) {
-                        for(i = strlen(buf)-1; i>=0; --i) {
-                                if (!isspace(buf[i]))
-                                        break;
-                        }
-                        buf[++i] = '\0';
-                        if ((buf[0]=='\0') || (buf[0]=='#'))
-                                continue;
-
-                        if (strcmp(buf, tty)== 0) {
-                                fclose(fp);
-                                return 1;
-                        }
+        if (!fp) {
+                /* A missing securetty file is not an error. */
+                return 1;
+        }
+        while (fgets(buf, sizeof(buf)-1, fp)) {
+                for(i = strlen(buf)-1; i>=0; --i) {
+                        if (!isspace(buf[i]))
+                                break;
+                }
+                buf[++i] = '\0';
+                if ((buf[0]=='\0') || (buf[0]=='#'))
+                        continue;
+                if (strcmp(buf, short_tty) == 0) {
+                        fclose(fp);
+                        return 1;
                 }
-                fclose(fp);
-                return 0;
         }
-        /* A missing securetty file is not an error. */
-        return 1;
+        fclose(fp);
+        return 0;
 }
 
 #endif
 
 /* returns 1 if true */
-static int is_my_tty(const char *tty)
+static int is_my_tty(void)
 {
         struct stat by_name, by_fd;
 
-        if (stat(tty, &by_name) || fstat(0, &by_fd))
+        if (stat(full_tty, &by_name) || fstat(0, &by_fd))
                 return 0;
 
         if (by_name.st_rdev != by_fd.st_rdev)
@@ -414,15 +378,10 @@ static void motd(void)
 
 
 #ifdef CONFIG_FEATURE_UTMP
-// vv  Taken from tinylogin utmp.c  vv
-
-#define NO_UTENT \
-        "No utmp entry.  You must exec \"login\" from the lowest level \"sh\""
-#define NO_TTY \
-        "Unable to determine your tty name."
+/* vv  Taken from tinylogin utmp.c  vv */
 
 /*
- * checkutmp - see if utmp file is correct for this process
+ * read_or_build_utent - see if utmp file is correct for this process
  *
  *      System V is very picky about the contents of the utmp file
  *      and requires that a slot for the current process exist.
@@ -435,9 +394,8 @@ static void motd(void)
  *      command line flags.
  */
 
-static void checkutmp(int picky)
+static void read_or_build_utent(int picky)
 {
-        char *line;
         struct utmp *ut;
         pid_t pid = getpid();
 
@@ -446,53 +404,41 @@ static void checkutmp(int picky)
         /* First, try to find a valid utmp entry for this process.  */
         while ((ut = getutent()))
                 if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] &&
-                        (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS))
+                (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS))
                         break;
 
         /* If there is one, just use it, otherwise create a new one.  */
         if (ut) {
                 utent = *ut;
         } else {
-                time_t t_tmp;
-                
-                if (picky) {
-                        puts(NO_UTENT);
-                        exit(1);
-                }
-                line = ttyname(0);
-                if (!line) {
-                        puts(NO_TTY);
-                        exit(1);
-                }
-                if (strncmp(line, "/dev/", 5) == 0)
-                        line += 5;
+                if (picky)
+                        bb_error_msg_and_die("no utmp entry found");
+
                 memset(&utent, 0, sizeof(utent));
                 utent.ut_type = LOGIN_PROCESS;
                 utent.ut_pid = pid;
-                strncpy(utent.ut_line, line, sizeof(utent.ut_line));
-                /* XXX - assumes /dev/tty?? */
-                strncpy(utent.ut_id, utent.ut_line + 3, sizeof(utent.ut_id));
+                strncpy(utent.ut_line, short_tty, sizeof(utent.ut_line));
+                /* This one is only 4 chars wide. Try to fit something
+                 * remotely meaningful by skipping "tty"... */
+                strncpy(utent.ut_id, short_tty + 3, sizeof(utent.ut_id));
                 strncpy(utent.ut_user, "LOGIN", sizeof(utent.ut_user));
-                t_tmp = (time_t)utent.ut_time;
-                time(&t_tmp);
+                utent.ut_time = time(NULL);
         }
 }
 
 /*
- * setutmp - put a USER_PROCESS entry in the utmp file
+ * write_utent - put a USER_PROCESS entry in the utmp file
  *
- *      setutmp changes the type of the current utmp entry to
+ *      write_utent changes the type of the current utmp entry to
  *      USER_PROCESS.  the wtmp file will be updated as well.
  */
 
-static void setutmp(const char *name, const char *line ATTRIBUTE_UNUSED)
+static void write_utent(const char *username)
 {
-        time_t t_tmp = (time_t)utent.ut_time;
-
         utent.ut_type = USER_PROCESS;
-        strncpy(utent.ut_user, name, sizeof(utent.ut_user));
-        time(&t_tmp);
-        /* other fields already filled in by checkutmp above */
+        strncpy(utent.ut_user, username, sizeof(utent.ut_user));
+        utent.ut_time = time(NULL);
+        /* other fields already filled in by read_or_build_utent above */
         setutent();
         pututline(&utent);
         endutent();