krb5 commit: Fix gss-krb5 handling of high sequence numbers

[Greg Hudson]

https://github.com/krb5/krb5/commit/dac8de0b26b9b67c1b03067c1ec90b81114ff370
commit dac8de0b26b9b67c1b03067c1ec90b81114ff370
Author: Greg Hudson <ghudson at mit.edu>
Date:   Sat Mar 27 00:52:05 2021 -0400

    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)

 src/lib/gssapi/krb5/accept_sec_context.c |    4 ++--
 src/lib/gssapi/krb5/init_sec_context.c   |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/lib/gssapi/krb5/accept_sec_context.c b/src/lib/gssapi/krb5/accept_sec_context.c
index cb62a25..d4e9079 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 8236560..ea87cf6 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)