openssh unix dev - Jun 2002 - [Bug 326] New: Bug in AFS token forwarding

http://bugzilla.mindrot.org/show_bug.cgi?id=326

           Summary: Bug in AFS token forwarding
           Product: Portable OpenSSH
           Version: -current
          Platform: ix86
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P4
         Component: ssh
        AssignedTo: openssh-unix-dev at mindrot.org
        ReportedBy: alfw at stanford.edu


There is a bug in the code for getting AFS tokens in function
send_afs_tokens() in sshconnect1.c

Here is how the bug manifests itself:
If I have an AFS token that is still valid _and_ one that was valid but
is now expired then AFS token forwarding ignores both tokens instead
of forwarding the still valid one.

I can reproduce this problem on Red Hat Linux 7.2 systems with
OpenSSH-3.4p1 (and probably all older versions) compiled with
KTH-Krb4-1.1.1 (this is where the k_pioctl() function comes from; see
below). I am using OpenAFS-1.2.5. The same happens on Solaris 8
(OpenSSH-3.4p1, KTH-Krb4-1.1.1, IBM/Transarc ASF).

Here is the cause for the bug:
The problem is that k_pioctl() returns -1 and "errno" returns an error
code ENOTCONN for _all_ tokens it finds if there is an expired token present.
The loop has to continue in this case although the _data_ returned
by k_pioctl() is invalid. This invalidness can be checked by comparing
the length of the "ClearToken" component with the size of the
ClearToken
struct. In OpenSSH-3.4p1 this condition is checked in sshconnect1.c line
814. But it is wrong to "break" out of the loop because of this
condition.
Jumping to the next token is the correct behavior.
"errno" returns "EDOM" if all tokens are listed.

Here is a patch that fixes this bug:
--- sshconnect1.c.orig  Fri Jun 28 13:25:51 2002
+++ sshconnect1.c       Fri Jun 28 13:23:56 2002
@@ -797,7 +797,8 @@
                parms.in_size = sizeof(i);
                parms.out = buf;
                parms.out_size = sizeof(buf);
-               if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0)
+                k_pioctl(0, VIOCGETTOK, &parms, 0);
+               if(errno == EDOM)
                        break;
                p = buf;
 
@@ -811,8 +812,7 @@
 
                /* Get clear token. */
                memcpy(&len, p, sizeof(len));
-               if (len != sizeof(struct ClearToken))
-                       break;
+                if (len == sizeof(struct ClearToken)) {
                p += sizeof(len);
                memcpy(&ct, p, len);
                p += len;
@@ -848,6 +848,7 @@
                        debug("AFS token for cell %s rejected.",
server_cell);
                else if (type != SSH_SMSG_SUCCESS)
                        packet_disconnect("Protocol error on AFS
tokenresponse:
%d", type);
+                }

        }
 }



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