Ticket History #5802: libgssapi mechglue doesn't always store delegated credentials

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Date: Mon, 1 Oct 2007 15:36:33 -0400
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Nalin

System: Linux blade.boston.redhat.com 2.6.23-0.211.rc8.git2.fc8 #1 SMP Thu Sep 27 18:21:00 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
Architecture: x86_64

The mechglue wrapper for gss_init_sec_context doesn't appear to be
handling the ret_flags parameter correctly.
* If the caller passes in NULL, the mechanism-specific function can't
store its own returned flags, so the wrapper can't dependably
be expected to store delegated credentials.
* The wrapper also appears to be checking for the bit in ret_flags
(which is a pointer to a bitfield) incorrectly.
Using elinks to perform negotiate authentication to a patched
mod_auth_kerb (both found in RHEL, if that helps), this happens
pretty reliably.
Proposed patch:

Index: src/lib/gssapi/mechglue/g_accept_sec_context.c
===================================================================
--- src/lib/gssapi/mechglue/g_accept_sec_context.c (revision 20038)
+++ src/lib/gssapi/mechglue/g_accept_sec_context.c (working copy)
@@ -112,6 +112,7 @@

{
OM_uint32 status, temp_status, temp_minor_status;
+ OM_uint32 temp_ret_flags = 0;
gss_union_ctx_id_t union_ctx_id;
gss_union_cred_t union_cred;
gss_cred_id_t input_cred_handle = GSS_C_NO_CREDENTIAL;
@@ -202,7 +203,7 @@
&internal_name,
mech_type,
output_token,
- ret_flags,
+ &temp_ret_flags,
time_rec,
d_cred ? &tmp_d_cred : NULL);

@@ -248,7 +249,7 @@
}

/* Ensure we're returning correct creds format */
- if ((ret_flags && GSS_C_DELEG_FLAG) &&
+ if ((temp_ret_flags & GSS_C_DELEG_FLAG) &&
tmp_d_cred != GSS_C_NO_CREDENTIAL) {
gss_union_cred_t d_u_cred = NULL;

@@ -335,6 +336,8 @@
if (src_name == NULL && tmp_src_name != NULL)
(void) gss_release_name(&temp_minor_status,
&tmp_src_name);
+ if (ret_flags != NULL)
+ *ret_flags = temp_ret_flags;
return (status);
} else {

On second thought, the proposed change will always store delegated
credentials, even when the calling application didn't pass in ret_flags,
and therefore might not care. A replacement for just the second hunk:

Apply patch from Nalin Dahyabhai to correctly handle delegated
credentials if ret_flags is null.


Commit By: tlyu



Revision: 20082
Changed Files:
_U trunk/
U trunk/src/lib/gssapi/mechglue/g_accept_sec_context.c

pull up r20082 from trunk

r20082@cathode-dark-space: tlyu | 2007-10-02 20:17:27 -0400
ticket: 5802
target_version: 1.6.3
tags: pullup

Apply patch from Nalin Dahyabhai to correctly handle delegated
credentials if ret_flags is null.




Commit By: tlyu



Revision: 20083
Changed Files:
_U branches/krb5-1-6/
U branches/krb5-1-6/src/lib/gssapi/mechglue/g_accept_sec_context.c