ftpd: add optional support for authentication

function                                             old     new   delta
cmdio_get_cmd_and_arg                                  -     237    +237
get_passwd                                             -      97     +97
check_password                                         -      82     +82
ftpd_main                                           2297    2178    -119
ask_and_check_password_extended                      206      84    -122
------------------------------------------------------------------------------
(add/remove: 3/0 grow/shrink: 0/2 up/down: 416/-241)          Total: 175 bytes

Signed-off-by: Morten Kvistgaard <MK@pch-engineering.dk>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 31 insertions, 23 deletions

diff --git a/networking/Config.src b/networking/Config.src
index fbad7ecb2..e56646917 100644
--- a/networking/Config.src
+++ b/networking/Config.src
@@ -134,6 +134,13 @@ config FEATURE_FTPD_ACCEPT_BROKEN_LIST
           it increases the code size by ~40 bytes.
           Most other ftp servers seem to behave similar to this.
 
+config FEATURE_FTP_AUTHENTICATION
+        bool "Enable authentication"
+        default y
+        depends on FTPD
+        help
+          Enable basic system login as seen in telnet etc.
+
 config FTPGET
         bool "ftpget"
         default y
diff --git a/networking/ftpd.c b/networking/ftpd.c
index 2d2a3a44c..9fcc3e963 100644
--- a/networking/ftpd.c
+++ b/networking/ftpd.c
@@ -1172,18 +1172,6 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv)
         if (logmode)
                 applet_name = xasprintf("%s[%u]", applet_name, (int)getpid());
 
-#if !BB_MMU
-        G.root_fd = -1;
-#endif
-        argv += optind;
-        if (argv[0]) {
-#if !BB_MMU
-                G.root_fd = xopen("/", O_RDONLY | O_DIRECTORY);
-                close_on_exec_on(G.root_fd);
-#endif
-                xchroot(argv[0]);
-        }
-
         //umask(077); - admin can set umask before starting us
 
         /* Signals. We'll always take -EPIPE rather than a rude signal, thanks */
@@ -1199,23 +1187,22 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv)
         WRITE_OK(FTP_GREET);
         signal(SIGALRM, timeout_handler);
 
-#ifdef IF_WE_WANT_TO_REQUIRE_LOGIN
+#if ENABLE_FEATURE_FTP_AUTHENTICATION
         {
-                smallint user_was_specified = 0;
+                struct passwd *pw = NULL;
+
                 while (1) {
                         uint32_t cmdval = cmdio_get_cmd_and_arg();
 
                         if (cmdval == const_USER) {
-                                if (G.ftp_arg == NULL || strcasecmp(G.ftp_arg, "anonymous") != 0)
-                                        cmdio_write_raw(STR(FTP_LOGINERR)" Server is anonymous only\r\n");
-                                else {
-                                        user_was_specified = 1;
-                                        cmdio_write_raw(STR(FTP_GIVEPWORD)" Please specify the password\r\n");
-                                }
+                                pw = getpwnam(G.ftp_arg);
+                                cmdio_write_raw(STR(FTP_GIVEPWORD)" Please specify password\r\n");
                         } else if (cmdval == const_PASS) {
-                                if (user_was_specified)
-                                        break;
-                                cmdio_write_raw(STR(FTP_NEEDUSER)" Login with USER\r\n");
+                                if (check_password(pw, G.ftp_arg) > 0) {
+                                        break;  /* login success */
+                                }
+                                cmdio_write_raw(STR(FTP_LOGINERR)" Login failed\r\n");
+                                pw = NULL;
                         } else if (cmdval == const_QUIT) {
                                 WRITE_OK(FTP_GOODBYE);
                                 return 0;
@@ -1223,10 +1210,24 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv)
                                 cmdio_write_raw(STR(FTP_LOGINERR)" Login with USER and PASS\r\n");
                         }
                 }
+                change_identity(pw);
         }
         WRITE_OK(FTP_LOGINOK);
 #endif
 
+        /* Do this after auth, else /etc/passwd is not accessible */
+#if !BB_MMU
+        G.root_fd = -1;
+#endif
+        argv += optind;
+        if (argv[0]) {
+#if !BB_MMU
+                G.root_fd = xopen("/", O_RDONLY | O_DIRECTORY);
+                close_on_exec_on(G.root_fd);
+#endif
+                xchroot(argv[0]);
+        }
+
         /* RFC-959 Section 5.1
          * The following commands and options MUST be supported by every
          * server-FTP and user-FTP, except in cases where the underlying