flush typeahead before prompt

[oweals/busybox.git] / loginutils / login.c

diff --git a/loginutils/login.c b/loginutils/login.c
index dfdc58b30b1d58802cec4f1bb22c4d5b34f563f5..c1e0c769973dffcf518dbda4c34c7e5962997c11 100644 (file)
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -201,7 +201,7 @@ static void motd(void)
        int fd;
 
        fd = open(bb_path_motd_file, O_RDONLY);
-       if (fd) {
+       if (fd >= 0) {
                fflush(stdout);
                bb_copyfd_eof(fd, STDOUT_FILENO);
                close(fd);
@@ -216,10 +216,14 @@ static void alarm_handler(int sig ATTRIBUTE_UNUSED)
        ndelay_on(1);
        ndelay_on(2);
        printf("\r\nLogin timed out after %d seconds\r\n", TIMEOUT);
+       /* unix API is brain damaged regarding O_NONBLOCK,
+        * we should undo it, or else we can affect other processes */
+       ndelay_off(1);
+       ndelay_off(2);
        exit(EXIT_SUCCESS);
 }
 
-int login_main(int argc, char **argv);
+int login_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int login_main(int argc, char **argv)
 {
        enum {
@@ -239,9 +243,14 @@ int login_main(int argc, char **argv)
        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;)
+#if ENABLE_PAM
+       int pamret;
+       pam_handle_t *pamh;
+       const char *pamuser;
+       const char *failed_msg;
+       struct passwd pwdstruct;
+       char pwdbuf[256];
+#endif
 
        short_tty = full_tty;
        username[0] = '\0';
@@ -254,6 +263,11 @@ int login_main(int argc, char **argv)
         * and any extra open fd's are closed.
         * (The name of the function is misleading. Not daemonizing here.) */
        bb_daemonize_or_rexec(DAEMON_ONLY_SANITIZE | DAEMON_CLOSE_EXTRA_FDS, NULL);
+       /* More of suid paranoia if called by non-root */
+       if (!amroot) {
+               /* Clear dangerous stuff, set PATH */
+               sanitize_env_for_suid();
+       }
 
        opt = getopt32(argv, "f:h:p", &opt_user, &opt_host);
        if (opt & LOGIN_OPT_f) {
@@ -291,24 +305,28 @@ int login_main(int argc, char **argv)
        openlog(applet_name, LOG_PID | LOG_CONS | LOG_NOWAIT, LOG_AUTH);
 
        while (1) {
+
+               /* flush away any type-ahead (as getty does) */
+               (void) ioctl(0, TCFLSH, TCIFLUSH);
+
                if (!username[0])
                        get_username_or_die(username, sizeof(username));
 
 #if ENABLE_PAM
                pamret = pam_start("login", username, &conv, &pamh);
                if (pamret != PAM_SUCCESS) {
-                       failed_msg = "pam_start";
+                       failed_msg = "start";
                        goto pam_auth_failed;
                }
                /* set TTY (so things like securetty work) */
                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"
                         * since user seems to enter wrong password
@@ -318,28 +336,42 @@ int login_main(int argc, char **argv)
                /* check that the account is healthy */
                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));
+               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 we get here, the user was authenticated, and is
-                * granted access. */
-               pw = getpwnam(username);
-               if (pw)
-                       break;
-               goto 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);
+               bb_error_msg("pam_%s call failed: %s (%d)", failed_msg,
+                                       pam_strerror(pamh, pamret), pamret);
                safe_strncpy(username, "UNKNOWN", sizeof(username));
 #else /* not PAM */
                pw = getpwnam(username);
@@ -411,7 +443,8 @@ int login_main(int argc, char **argv)
        fchown(0, pw->pw_uid, pw->pw_gid);
        fchmod(0, 0600);
 
-       if (ENABLE_LOGIN_SCRIPTS) {
+       /* We trust environment only if we run by root */
+       if (ENABLE_LOGIN_SCRIPTS && amroot) {
                char *t_argv[2];
 
                t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT");