Changeset 2725 in MondoRescue for branches/2.2.9/mindi-busybox/loginutils/login.c

Timestamp:

Feb 25, 2011, 9:26:54 PM (13 years ago)

Author:

Bruno Cornec

Message:

• Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3

File:

• branches/2.2.9/mindi-busybox/loginutils/login.c (modified) (17 diffs)

branches/2.2.9/mindi-busybox/loginutils/login.c

@@ -1 +1 @@
 /* vi: set sw=4 ts=4: */
 /*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
-
 #include "libbb.h"
-#include <utmp.h>
+#include <syslog.h>
+#if ENABLE_FEATURE_UTMP
+# include <utmp.h> /* USER_PROCESS */
+#endif
 #include <sys/resource.h>
-#include <syslog.h>
 
 #if ENABLE_SELINUX
-#include <selinux/selinux.h>  /* for is_selinux_enabled()  */
-#include <selinux/get_context_list.h> /* for get_default_context() */
-#include <selinux/flask.h> /* for security class definitions  */
+# include <selinux/selinux.h>  /* for is_selinux_enabled()  */
+# include <selinux/get_context_list.h> /* for get_default_context() */
+# include <selinux/flask.h> /* for security class definitions  */
 #endif
 
 #if ENABLE_PAM
 /* PAM may include <locale.h>. We may need to undefine bbox's stub define: */
-#undef setlocale
+# undef setlocale
 /* For some obscure reason, PAM is not in pam/xxx, but in security/xxx.
  * Apparently they like to confuse people. */
-#include <security/pam_appl.h>
-#include <security/pam_misc.h>
+# include <security/pam_appl.h>
+# include <security/pam_misc.h>
 static const struct pam_conv conv = {
     misc_conv,
@@ -37 +38 @@
 static char* short_tty;
 
-#if ENABLE_FEATURE_UTMP
-/* vv  Taken from tinylogin utmp.c  vv */
-/*
- * 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.
- *  The utmp file is scanned for an entry with the same process
- *  ID.  If no entry exists the process exits with a message.
- *
- *  The "picky" flag is for network and other logins that may
- *  use special flags.  It allows the pid checks to be overridden.
- *  This means that getty should never invoke login with any
- *  command line flags.
- */
-
-static void read_or_build_utent(struct utmp *utptr, int picky)
-{
-    struct utmp *ut;
-    pid_t pid = getpid();
-
-    setutent();
-
-    /* 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))
-            break;
-
-    /* If there is one, just use it, otherwise create a new one.  */
-    if (ut) {
-        *utptr = *ut;
-    } else {
-        if (picky)
-            bb_error_msg_and_die("no utmp entry found");
-
-        memset(utptr, 0, sizeof(*utptr));
-        utptr->ut_type = LOGIN_PROCESS;
-        utptr->ut_pid = pid;
-        strncpy(utptr->ut_line, short_tty, sizeof(utptr->ut_line));
-        /* This one is only 4 chars wide. Try to fit something
-         * remotely meaningful by skipping "tty"... */
-        strncpy(utptr->ut_id, short_tty + 3, sizeof(utptr->ut_id));
-        strncpy(utptr->ut_user, "LOGIN", sizeof(utptr->ut_user));
-        utptr->ut_time = time(NULL);
-    }
-    if (!picky) /* root login */
-        memset(utptr->ut_host, 0, sizeof(utptr->ut_host));
-}
-
-/*
- * write_utent - put a USER_PROCESS entry in the utmp file
- *
- *  write_utent changes the type of the current utmp entry to
- *  USER_PROCESS.  the wtmp file will be updated as well.
- */
-static void write_utent(struct utmp *utptr, const char *username)
-{
-    utptr->ut_type = USER_PROCESS;
-    strncpy(utptr->ut_user, username, sizeof(utptr->ut_user));
-    utptr->ut_time = time(NULL);
-    /* other fields already filled in by read_or_build_utent above */
-    setutent();
-    pututline(utptr);
-    endutent();
-#if ENABLE_FEATURE_WTMP
-    if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) {
-        close(creat(bb_path_wtmp_file, 0664));
-    }
-    updwtmp(bb_path_wtmp_file, utptr);
-#endif
-}
-#else /* !ENABLE_FEATURE_UTMP */
-#define read_or_build_utent(utptr, picky) ((void)0)
-#define write_utent(utptr, username) ((void)0)
-#endif /* !ENABLE_FEATURE_UTMP */
-
 #if ENABLE_FEATURE_NOLOGIN
-static void die_if_nologin_and_non_root(int amroot)
+static void die_if_nologin(void)
 {
     FILE *fp;
     int c;
-
-    if (access("/etc/nologin", F_OK))
+    int empty = 1;
+
+    fp = fopen_for_read("/etc/nologin");
+    if (!fp) /* assuming it does not exist */
         return;
 
-    fp = fopen("/etc/nologin", "r");
-    if (fp) {
-        while ((c = getc(fp)) != EOF)
-            putchar((c=='\n') ? '\r' : c);
-        fflush(stdout);
-        fclose(fp);
-    } else
+    while ((c = getc(fp)) != EOF) {
+        if (c == '\n')
+            bb_putchar('\r');
+        bb_putchar(c);
+        empty = 0;
+    }
+    if (empty)
         puts("\r\nSystem closed for routine maintenance\r");
-    if (!amroot)
-        exit(1);
-    puts("\r\n[Disconnect bypassed -- root login allowed]\r");
+
+    fclose(fp);
+    fflush_all();
+    /* Users say that they do need this prior to exit: */
+    tcdrain(STDOUT_FILENO);
+    exit(EXIT_FAILURE);
 }
 #else
-static ALWAYS_INLINE void die_if_nologin_and_non_root(int amroot) {}
+# define die_if_nologin() ((void)0)
 #endif
 
@@ -142 +71 @@
 static int check_securetty(void)
 {
-    FILE *fp;
-    int i;
-    char buf[256];
-
-    fp = fopen("/etc/securetty", "r");
-    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] || (buf[0] == '#'))
-            continue;
-        if (strcmp(buf, short_tty) == 0) {
-            fclose(fp);
-            return 1;
-        }
-    }
-    fclose(fp);
-    return 0;
+    char *buf = (char*)"/etc/securetty"; /* any non-NULL is ok */
+    parser_t *parser = config_open2("/etc/securetty", fopen_for_read);
+    while (config_read(parser, &buf, 1, 1, "# \t", PARSE_NORMAL)) {
+        if (strcmp(buf, short_tty) == 0)
+            break;
+        buf = NULL;
+    }
+    config_close(parser);
+    /* buf != NULL here if config file was not found, empty
+     * or line was found which equals short_tty */
+    return buf != NULL;
 }
 #else
 static ALWAYS_INLINE int check_securetty(void) { return 1; }
+#endif
+
+#if ENABLE_SELINUX
+static void initselinux(char *username, char *full_tty,
+                        security_context_t *user_sid)
+{
+    security_context_t old_tty_sid, new_tty_sid;
+
+    if (!is_selinux_enabled())
+        return;
+
+    if (get_default_context(username, NULL, user_sid)) {
+        bb_error_msg_and_die("can't get SID for %s", username);
+    }
+    if (getfilecon(full_tty, &old_tty_sid) < 0) {
+        bb_perror_msg_and_die("getfilecon(%s) failed", full_tty);
+    }
+    if (security_compute_relabel(*user_sid, old_tty_sid,
+                SECCLASS_CHR_FILE, &new_tty_sid) != 0) {
+        bb_perror_msg_and_die("security_change_sid(%s) failed", full_tty);
+    }
+    if (setfilecon(full_tty, new_tty_sid) != 0) {
+        bb_perror_msg_and_die("chsid(%s, %s) failed", full_tty, new_tty_sid);
+    }
+}
+#endif
+
+#if ENABLE_LOGIN_SCRIPTS
+static void run_login_script(struct passwd *pw, char *full_tty)
+{
+    char *t_argv[2];
+
+    t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");
+    if (t_argv[0]) {
+        t_argv[1] = NULL;
+        xsetenv("LOGIN_TTY", full_tty);
+        xsetenv("LOGIN_USER", pw->pw_name);
+        xsetenv("LOGIN_UID", utoa(pw->pw_uid));
+        xsetenv("LOGIN_GID", utoa(pw->pw_gid));
+        xsetenv("LOGIN_SHELL", pw->pw_shell);
+        spawn_and_wait(t_argv); /* NOMMU-friendly */
+        unsetenv("LOGIN_TTY");
+        unsetenv("LOGIN_USER");
+        unsetenv("LOGIN_UID");
+        unsetenv("LOGIN_GID");
+        unsetenv("LOGIN_SHELL");
+    }
+}
+#else
+void run_login_script(struct passwd *pw, char *full_tty);
 #endif
 
@@ -181 +147 @@
     do {
         c = getchar();
-        if (c == EOF) exit(1);
+        if (c == EOF)
+            exit(EXIT_FAILURE);
         if (c == '\n') {
-            if (!--cntdown) exit(1);
+            if (!--cntdown)
+                exit(EXIT_FAILURE);
             goto prompt;
         }
-    } while (isspace(c));
+    } while (isspace(c)); /* maybe isblank? */
 
     *buf++ = c;
     if (!fgets(buf, size_buf-2, stdin))
-        exit(1);
+        exit(EXIT_FAILURE);
     if (!strchr(buf, '\n'))
-        exit(1);
-    while (isgraph(*buf)) buf++;
+        exit(EXIT_FAILURE);
+    while ((unsigned char)*buf > ' ')
+        buf++;
     *buf = '\0';
 }
@@ -202 +171 @@
 
     fd = open(bb_path_motd_file, O_RDONLY);
-    if (fd) {
-        fflush(stdout);
+    if (fd >= 0) {
+        fflush_all();
         bb_copyfd_eof(fd, STDOUT_FILENO);
         close(fd);
@@ -209 +178 @@
 }
 
-static void alarm_handler(int sig ATTRIBUTE_UNUSED)
+static void alarm_handler(int sig UNUSED_PARAM)
 {
     /* This is the escape hatch!  Poor serial line users and the like
@@ -215 +184 @@
      * We don't want to block here */
     ndelay_on(1);
-    ndelay_on(2);
     printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
-    exit(EXIT_SUCCESS);
-}
-
-int login_main(int argc, char **argv);
-int login_main(int argc, char **argv)
+    fflush_all();
+    /* unix API is brain damaged regarding O_NONBLOCK,
+     * we should undo it, or else we can affect other processes */
+    ndelay_off(1);
+    _exit(EXIT_SUCCESS);
+}
+
+int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int login_main(int argc UNUSED_PARAM, char **argv)
 {
     enum {
@@ -230 +202 @@
     char *fromhost;
     char username[USERNAME_SIZE];
-    const char *tmp;
-    int amroot;
+    const char *shell;
+    int run_by_root;
     unsigned opt;
     int count = 0;
     struct passwd *pw;
     char *opt_host = NULL;
-    char *opt_user = NULL;
-    char full_tty[TTYNAME_SIZE];
-    USE_SELINUX(security_context_t user_sid = NULL;)
-    USE_FEATURE_UTMP(struct utmp utent;)
-    USE_PAM(pam_handle_t *pamh;)
-    USE_PAM(int pamret;)
-    USE_PAM(const char *failed_msg;)
-
-    short_tty = full_tty;
+    char *opt_user = opt_user; /* for compiler */
+    char *full_tty;
+    IF_SELINUX(security_context_t user_sid = NULL;)
+#if ENABLE_PAM
+    int pamret;
+    pam_handle_t *pamh;
+    const char *pamuser;
+    const char *failed_msg;
+    struct passwd pwdstruct;
+    char pwdbuf[256];
+#endif
+
     username[0] = '\0';
-    amroot = (getuid() == 0);
     signal(SIGALRM, alarm_handler);
     alarm(TIMEOUT);
+
+    /* More of suid paranoia if called by non-root: */
+    /* Clear dangerous stuff, set PATH */
+    run_by_root = !sanitize_env_if_suid();
 
     /* Mandatory paranoia for suid applet:
@@ -258 +236 @@
     opt = getopt32(argv, "f:h:p", &opt_user, &opt_host);
     if (opt & LOGIN_OPT_f) {
-        if (!amroot)
+        if (!run_by_root)
             bb_error_msg_and_die("-f is for root only");
         safe_strncpy(username, opt_user, sizeof(username));
     }
-    if (optind < argc) /* user from command line (getty) */
-        safe_strncpy(username, argv[optind], sizeof(username));
+    argv += optind;
+    if (argv[0]) /* user from command line (getty) */
+        safe_strncpy(username, argv[0], sizeof(username));
 
     /* Let's find out and memorize our tty */
-    if (!isatty(0) || !isatty(1) || !isatty(2))
-        return EXIT_FAILURE;        /* Must be a terminal */
-    safe_strncpy(full_tty, "UNKNOWN", sizeof(full_tty));
-    tmp = ttyname(0);
-    if (tmp) {
-        safe_strncpy(full_tty, tmp, sizeof(full_tty));
-        if (strncmp(full_tty, "/dev/", 5) == 0)
-            short_tty = full_tty + 5;
-    }
-
-    read_or_build_utent(&utent, !amroot);
+    if (!isatty(STDIN_FILENO) || !isatty(STDOUT_FILENO) || !isatty(STDERR_FILENO))
+        return EXIT_FAILURE;  /* Must be a terminal */
+    full_tty = xmalloc_ttyname(STDIN_FILENO);
+    if (!full_tty)
+        full_tty = xstrdup("UNKNOWN");
+    short_tty = skip_dev_pfx(full_tty);
 
     if (opt_host) {
-        USE_FEATURE_UTMP(
-            safe_strncpy(utent.ut_host, opt_host, sizeof(utent.ut_host));
-        )
         fromhost = xasprintf(" on '%s' from '%s'", short_tty, opt_host);
-    } else
+    } else {
         fromhost = xasprintf(" on '%s'", short_tty);
+    }
 
     /* Was breaking "login <username>" from shell command line: */
     /*bb_setpgrp();*/
 
-    openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
+    openlog(applet_name, LOG_PID | LOG_CONS, LOG_AUTH);
 
     while (1) {
+        /* flush away any type-ahead (as getty does) */
+        tcflush(0, TCIFLUSH);
+
         if (!username[0])
             get_username_or_die(username, sizeof(username));
@@ -298 +273 @@
         pamret = pam_start("login", username, &conv, &pamh);
         if (pamret != PAM_SUCCESS) {
-            failed_msg = "pam_start";
+            failed_msg = "start";
             goto pam_auth_failed;
         }
@@ -304 +279 @@
         pamret = pam_set_item(pamh, PAM_TTY, short_tty);
         if (pamret != PAM_SUCCESS) {
-            failed_msg = "pam_set_item(TTY)";
+            failed_msg = "set_item(TTY)";
             goto pam_auth_failed;
         }
         pamret = pam_authenticate(pamh, 0);
         if (pamret != PAM_SUCCESS) {
-            failed_msg = "pam_authenticate";
+            failed_msg = "authenticate";
             goto pam_auth_failed;
             /* TODO: or just "goto auth_failed"
@@ -319 +294 @@
         pamret = pam_acct_mgmt(pamh, 0);
         if (pamret != PAM_SUCCESS) {
-            failed_msg = "account setup";
+            failed_msg = "acct_mgmt";
             goto pam_auth_failed;
         }
         /* read user back */
-        {
-            const char *pamuser;
-            /* gcc: "dereferencing type-punned pointer breaks aliasing rules..."
-             * thus we cast to (void*) */
-            if (pam_get_item(pamh, PAM_USER, (void*)&pamuser) != PAM_SUCCESS) {
-                failed_msg = "pam_get_item(USER)";
-                goto pam_auth_failed;
-            }
-            safe_strncpy(username, pamuser, sizeof(username));
-        }
-        /* If we get here, the user was authenticated, and is
-         * granted access. */
-        pw = getpwnam(username);
-        if (pw)
-            break;
-        goto auth_failed;
+        pamuser = NULL;
+        /* gcc: "dereferencing type-punned pointer breaks aliasing rules..."
+         * thus we cast to (void*) */
+        if (pam_get_item(pamh, PAM_USER, (void*)&pamuser) != PAM_SUCCESS) {
+            failed_msg = "get_item(USER)";
+            goto pam_auth_failed;
+        }
+        if (!pamuser || !pamuser[0])
+            goto auth_failed;
+        safe_strncpy(username, pamuser, sizeof(username));
+        /* Don't use "pw = getpwnam(username);",
+         * PAM is said to be capable of destroying static storage
+         * used by getpwnam(). We are using safe(r) function */
+        pw = NULL;
+        getpwnam_r(username, &pwdstruct, pwdbuf, sizeof(pwdbuf), &pw);
+        if (!pw)
+            goto auth_failed;
+        pamret = pam_open_session(pamh, 0);
+        if (pamret != PAM_SUCCESS) {
+            failed_msg = "open_session";
+            goto pam_auth_failed;
+        }
+        pamret = pam_setcred(pamh, PAM_ESTABLISH_CRED);
+        if (pamret != PAM_SUCCESS) {
+            failed_msg = "setcred";
+            goto pam_auth_failed;
+        }
+        break; /* success, continue login process */
+
  pam_auth_failed:
-        bb_error_msg("%s failed: %s (%d)", failed_msg, pam_strerror(pamh, pamret), pamret);
+        /* syslog, because we don't want potential attacker
+         * to know _why_ login failed */
+        syslog(LOG_WARNING, "pam_%s call failed: %s (%d)", failed_msg,
+                    pam_strerror(pamh, pamret), pamret);
         safe_strncpy(username, "UNKNOWN", sizeof(username));
 #else /* not PAM */
@@ -374 +365 @@
             syslog(LOG_WARNING, "invalid password for '%s'%s",
                         username, fromhost);
+
+            if (ENABLE_FEATURE_CLEAN_UP)
+                free(fromhost);
+
             return EXIT_FAILURE;
         }
         username[0] = '\0';
-    }
+    } /* while (1) */
 
     alarm(0);
-    die_if_nologin_and_non_root(pw->pw_uid == 0);
-
-    write_utent(&utent, username);
-
-#if ENABLE_SELINUX
-    if (is_selinux_enabled()) {
-        security_context_t old_tty_sid, new_tty_sid;
-
-        if (get_default_context(username, NULL, &user_sid)) {
-            bb_error_msg_and_die("cannot get SID for %s",
-                    username);
-        }
-        if (getfilecon(full_tty, &old_tty_sid) < 0) {
-            bb_perror_msg_and_die("getfilecon(%s) failed",
-                    full_tty);
-        }
-        if (security_compute_relabel(user_sid, old_tty_sid,
-                    SECCLASS_CHR_FILE, &new_tty_sid) != 0) {
-            bb_perror_msg_and_die("security_change_sid(%s) failed",
-                    full_tty);
-        }
-        if (setfilecon(full_tty, new_tty_sid) != 0) {
-            bb_perror_msg_and_die("chsid(%s, %s) failed",
-                    full_tty, new_tty_sid);
-        }
-    }
-#endif
+    /* We can ignore /etc/nologin if we are logging in as root,
+     * it doesn't matter whether we are run by root or not */
+    if (pw->pw_uid != 0)
+        die_if_nologin();
+
+    IF_SELINUX(initselinux(username, full_tty, &user_sid));
+
     /* Try these, but don't complain if they fail.
      * _f_chown is safe wrt race t=ttyname(0);...;chown(t); */
@@ -412 +387 @@
     fchmod(0, 0600);
 
-    if (ENABLE_LOGIN_SCRIPTS) {
-        char *t_argv[2];
-
-        t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");
-        if (t_argv[0]) {
-            t_argv[1] = NULL;
-            xsetenv("LOGIN_TTY", full_tty);
-            xsetenv("LOGIN_USER", pw->pw_name);
-            xsetenv("LOGIN_UID", utoa(pw->pw_uid));
-            xsetenv("LOGIN_GID", utoa(pw->pw_gid));
-            xsetenv("LOGIN_SHELL", pw->pw_shell);
-            xspawn(t_argv); /* NOMMU-friendly */
-            /* All variables are unset by setup_environment */
-            wait(NULL);
-        }
-    }
+    update_utmp(getpid(), USER_PROCESS, short_tty, username, run_by_root ? opt_host : NULL);
+
+    /* We trust environment only if we run by root */
+    if (ENABLE_LOGIN_SCRIPTS && run_by_root)
+        run_login_script(pw, full_tty);
 
     change_identity(pw);
-    tmp = pw->pw_shell;
-    if (!tmp || !*tmp)
-        tmp = DEFAULT_SHELL;
-    /* setup_environment params: shell, loginshell, changeenv, pw */
-    setup_environment(tmp, 1, !(opt & LOGIN_OPT_p), pw);
-    /* FIXME: login shell = 1 -> 3rd parameter is ignored! */
+    shell = pw->pw_shell;
+    if (!shell || !shell[0])
+        shell = DEFAULT_SHELL;
+    setup_environment(shell,
+            (!(opt & LOGIN_OPT_p) * SETUP_ENV_CLEARENV) + SETUP_ENV_CHANGEENV,
+            pw);
 
     motd();
@@ -441 +405 @@
     if (pw->pw_uid == 0)
         syslog(LOG_INFO, "root login%s", fromhost);
-#if ENABLE_SELINUX
+
+    if (ENABLE_FEATURE_CLEAN_UP)
+        free(fromhost);
+
     /* well, a simple setexeccon() here would do the job as well,
      * but let's play the game for now */
-    set_current_security_context(user_sid);
-#endif
+    IF_SELINUX(set_current_security_context(user_sid);)
 
     // util-linux login also does:
@@ -456 +422 @@
     // If this stuff is really needed, add it and explain why!
 
-    /* set signals to defaults */
-    signal(SIGALRM, SIG_DFL);
+    /* Set signals to defaults */
+    /* Non-ignored signals revert to SIG_DFL on exec anyway */
+    /*signal(SIGALRM, SIG_DFL);*/
+
     /* Is this correct? This way user can ctrl-c out of /etc/profile,
      * potentially creating security breach (tested with bash 3.0).
@@ -463 +431 @@
      * Maybe bash is buggy?
      * Need to find out what standards say about /bin/login -
-     * should it leave SIGINT etc enabled or disabled? */
+     * should we leave SIGINT etc enabled or disabled? */
     signal(SIGINT, SIG_DFL);
 
     /* Exec login shell with no additional parameters */
-    run_shell(tmp, 1, NULL, NULL);
+    run_shell(shell, 1, NULL, NULL);
 
     /* return EXIT_FAILURE; - not reached */