From: Greg Hudson <ghudson@mit.edu>
Date: Sat, 27 Mar 2021 04:52:05 +0000 (-0400)
Subject: Fix gss-krb5 handling of high sequence numbers
X-Git-Tag: krb5-1.20-beta1~105
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dac8de0b26b9b67c1b03067c1ec90b81114ff370;p=thirdparty%2Fkrb5.git

Fix gss-krb5 handling of high sequence numbers

Commits abcfdaff756631d73f49103f679cafa7bc45f14e and
41ddaaeb286e8bb1bba64fb557ba0e4cff9b404d incorrectly changed the
interpretation of authenticator sequence numbers in the range
2^31..2^32-1, mapping them to sign-extended 64-bit values.  The major
Kerberos implementations do not generate sequence numbers this large,
so the changed went unnoticed.  Prevent unwanted sign extension by
casting sequence numbers retrieved from auth contexts to uint32_t
before assigning them to uint64_t fields.  Reported by Jake Scott.

ticket: 8994 (new)
---

diff --git a/src/lib/gssapi/krb5/accept_sec_context.c b/src/lib/gssapi/krb5/accept_sec_context.c
index cb62a25ec8..d4e90793f9 100644
--- a/src/lib/gssapi/krb5/accept_sec_context.c
+++ b/src/lib/gssapi/krb5/accept_sec_context.c
@@ -982,7 +982,7 @@ kg_accept_krb5(minor_status, context_handle,
     {
         krb5_int32 seq_temp;
         krb5_auth_con_getremoteseqnumber(context, auth_context, &seq_temp);
-        ctx->seq_recv = seq_temp;
+        ctx->seq_recv = (uint32_t)seq_temp;
     }
 
     if ((code = krb5_timeofday(context, &now))) {
@@ -1065,7 +1065,7 @@ kg_accept_krb5(minor_status, context_handle,
         }
 
         krb5_auth_con_getlocalseqnumber(context, auth_context, &seq_temp);
-        ctx->seq_send = seq_temp & 0xffffffffL;
+        ctx->seq_send = (uint32_t)seq_temp;
 
         if (cfx_generate_subkey) {
             /* Get the new acceptor subkey.  With the code above, there
diff --git a/src/lib/gssapi/krb5/init_sec_context.c b/src/lib/gssapi/krb5/init_sec_context.c
index 8236560377..ea87cf6432 100644
--- a/src/lib/gssapi/krb5/init_sec_context.c
+++ b/src/lib/gssapi/krb5/init_sec_context.c
@@ -631,7 +631,7 @@ kg_new_connection(
         }
 
         krb5_auth_con_getlocalseqnumber(context, ctx->auth_context, &seq_temp);
-        ctx->seq_send = seq_temp;
+        ctx->seq_send = (uint32_t)seq_temp;
         code = krb5_auth_con_getsendsubkey(context, ctx->auth_context,
                                            &keyblock);
         if (code != 0)