[SCM] GNU Inetutils branch, master, updated. inetutils-1_9_1-193-gcc2173d

[Mats Erik Andersson]

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http://git.savannah.gnu.org/cgit/inetutils.git/commit/?id=cc2173d24f4c905b05c58e61ace0095f0deb1354


commit cc2173d24f4c905b05c58e61ace0095f0deb1354
Author: Mats Erik Andersson <address@hidden>
Date:   Tue Oct 23 19:58:02 2012 +0200

    ftpd: PAM messaging robustness.

diff --git a/ChangeLog b/ChangeLog
index b7f87fe..2ff9f4c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2012-10-23  Mats Erik Andersson  <address@hidden>
+
+       ftpd: PAM robustness.  Fine tune message passing,
+       since the finite state automata of FTP can choke
+       on some multiline messages.
+
+       * ftpd/extern.h (lreply_multiline): New prototype.
+       * ftpd/ftpd.c (user): Transmit a reply containing
+       only a single line, cutting at the last newline.
+       (pass): If the credential of an authenticated user
+       contains a message, reply using lreply_multiline().
+       (lreply_multiline): New function.
+       * ftpd/pam.c (PAM_conv): Insert a newline character
+       between concatenated message strings.  Remove only
+       trailing whitespace, leaving any colon untouched.
+       (pam_doit): Compare message string to `password:',
+       including a colon.
+
 2012-10-19  Mats Erik Andersson  <address@hidden>
 
        syslogd: Portability of utmp.  Disclosed by Solaris 11.
diff --git a/ftpd/extern.h b/ftpd/extern.h
index 7012be6..a10317d 100644
--- a/ftpd/extern.h
+++ b/ftpd/extern.h
@@ -66,6 +66,7 @@ extern FILE *ftpd_popen (char *, const char *);
 extern char *getusershell (void);
 #endif
 extern void lreply (int, const char *, ...);
+extern void lreply_multiline (int n, const char *text);
 extern void makedir (const char *);
 extern void nack (const char *);
 extern void pass (const char *);
diff --git a/ftpd/ftpd.c b/ftpd/ftpd.c
index 5ba5e24..11a69fb 100644
--- a/ftpd/ftpd.c
+++ b/ftpd/ftpd.c
@@ -795,7 +795,20 @@ user (const char *name)
 
   if (cred.message)
     {
-      reply (331, "%s", cred.message);
+      /* Stacked PAM modules for authentication may have
+       * produced a multiline message at this point.
+       * The FTP protocol does not cope well with this,
+       * so we transfer only the very last line, which
+       * should reflect the active authentication mechanism.
+       */
+      char *msg = strrchr (cred.message, '\n');
+
+      if (msg)
+       msg++;          /* Step over separator.  */
+      else
+       msg = cred.message;
+
+      reply (331, "%s", msg);
       free (cred.message);
       cred.message = NULL;
     }
@@ -883,6 +896,15 @@ pass (const char *passwd)
            }
          return;
        }
+      if (cred.message)
+       {
+         /* At least PAM might have committed additional messages.
+          * Reply code 230 is used, since at this point the client
+          * has been accepted.  */
+         lreply_multiline (230, cred.message);
+         free (cred.message);
+         cred.message = NULL;
+       }
     }
   cred.logged_in = 1;          /* Everything seems to be allright.  */
   complete_login (&cred);
@@ -1638,6 +1660,42 @@ lreply (int n, const char *fmt, ...)
     }
 }
 
+/* Send a possibly multiline reply as individual
+ * lines of message with identical status code.
+ * No format string input!
+ */
+void
+lreply_multiline (int n, const char *text)
+{
+  char *line;
+
+  line = strdup (text);
+  if (line == NULL)
+    return;
+  else
+    {
+      int stop = 0;
+      char *p1 = line, *p2;
+
+      do
+       {
+         p2 = strchrnul (p1, '\n');
+         stop = (*p2 == '\0');         /* End of input string?  */
+         *p2 = '\0';
+         printf ("%d- ", n);
+         printf ("%s\r\n", p1);
+         if (debug)
+           {
+             syslog (LOG_DEBUG, "<--- %d- ", n);
+             syslog (LOG_DEBUG, "%s", p1);
+           }
+         p1 = ++p2;                    /* P1 is used within bounds.  */
+       }
+      while (!stop);
+      free (line);
+    }
+}
+
 static void
 ack (const char *s)
 {
diff --git a/ftpd/pam.c b/ftpd/pam.c
index babb48d..ff08a7c 100644
--- a/ftpd/pam.c
+++ b/ftpd/pam.c
@@ -113,11 +113,18 @@ PAM_conv (int num_msg, const struct pam_message **msg,
             in the ftpd.c:user() or ftpd.c:pass() check for it and send
             a lreply().  But I'm not sure the RFCs allow mutilines replies
             for a passwd challenge.  Many clients will simply break.  */
+         /* XXX: Attempted solution; collect all messages, appended
+          * one after the other, separated by "\n".  Then print all
+          * of them in one single run.  This will circumvent the hard
+          * coded protocol convention of not allowing continuation
+          * massage to carry a deviating reply code relative to the
+          * final message.
+          */
          if (pcred->message)   /* XXX: make sure we split newlines correctly */
            {
              size_t len = strlen (pcred->message);
              char *s = realloc (pcred->message, len
-                                + strlen (msg[count]->msg) + 1);
+                                + strlen (msg[count]->msg) + 2);
              if (s == NULL)
                {
                  free (pcred->message);
@@ -126,6 +133,7 @@ PAM_conv (int num_msg, const struct pam_message **msg,
              else
                {
                  pcred->message = s;
+                 strcat (pcred->message, "\n");
                  strcat (pcred->message, msg[count]->msg);
                }
            }
@@ -137,10 +145,9 @@ PAM_conv (int num_msg, const struct pam_message **msg,
          else
            {
              char *sp;
-             /* FIXME:  What's this for ? */
-             /* Remove trailing `: ' */
+             /* Remove trailing space only.  */
              sp = pcred->message + strlen (pcred->message);
-             while (sp > pcred->message && strchr (" \t\n:", *--sp))
+             while (sp > pcred->message && strchr (" \t\n", *--sp))
                *sp = '\0';
            }
        }
@@ -180,7 +187,7 @@ pam_doit (struct credentials *pcred)
     {
       /* Avoid overly terse passwd messages and let the people
          upstairs do something sane.  */
-      if (pcred->message && !strcasecmp (pcred->message, "password"))
+      if (pcred->message && !strcasecmp (pcred->message, "password:"))
        {
          free (pcred->message);
          pcred->message = NULL;

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog     |   18 +++++++++++++++++
 ftpd/extern.h |    1 +
 ftpd/ftpd.c   |   60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 ftpd/pam.c    |   17 +++++++++++----
 4 files changed, 90 insertions(+), 6 deletions(-)


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