krb5 commit: Fix KCM flag transmission for remove_cred

[Greg Hudson]

https://github.com/krb5/krb5/commit/11a82cf424f9c905bb73680c64524f087090d4ef
commit 11a82cf424f9c905bb73680c64524f087090d4ef
Author: Greg Hudson <ghudson at mit.edu>
Date:   Mon Mar 29 14:32:56 2021 -0400

    Fix KCM flag transmission for remove_cred
    
    MIT krb5 uses low bits for KRB5_TC flags, while Heimdal uses high bits
    so that the same flag word can also hold KRB5_GC flags.  Add a mapping
    function and send the Heimdal flag values when performing a
    remove_cred operation.
    
    ticket: 8995

 src/include/kcm.h            |   19 +++++++++++++++++++
 src/lib/krb5/ccache/cc_kcm.c |   36 +++++++++++++++++++++++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletions(-)

diff --git a/src/include/kcm.h b/src/include/kcm.h
index e4140c3..9b66f1c 100644
--- a/src/include/kcm.h
+++ b/src/include/kcm.h
@@ -56,8 +56,27 @@
  * are marshalled as zero-terminated strings.  Principals and credentials are
  * marshalled in the v4 FILE ccache format.  UUIDs are 16 bytes.  UUID lists
  * are not delimited, so nothing can come after them.
+ *
+ * Flag words must use Heimdal flag values, which are not the same as MIT krb5
+ * values for KRB5_GC and KRB5_TC constants.  The same flag word may contain
+ * both kinds of flags in Heimdal, but not in MIT krb5.  Defines for the
+ * applicable Heimdal flag values are given below using KCM_GC and KCM_TC
+ * prefixes.
  */
 
+#define KCM_GC_CACHED                   (1U << 0)
+
+#define KCM_TC_DONT_MATCH_REALM         (1U << 31)
+#define KCM_TC_MATCH_KEYTYPE            (1U << 30)
+#define KCM_TC_MATCH_SRV_NAMEONLY       (1U << 29)
+#define KCM_TC_MATCH_FLAGS_EXACT        (1U << 28)
+#define KCM_TC_MATCH_FLAGS              (1U << 27)
+#define KCM_TC_MATCH_TIMES_EXACT        (1U << 26)
+#define KCM_TC_MATCH_TIMES              (1U << 25)
+#define KCM_TC_MATCH_AUTHDATA           (1U << 24)
+#define KCM_TC_MATCH_2ND_TKT            (1U << 23)
+#define KCM_TC_MATCH_IS_SKEY            (1U << 22)
+
 /* Opcodes without comments are currently unused in the MIT client
  * implementation. */
 typedef enum kcm_opcode {
diff --git a/src/lib/krb5/ccache/cc_kcm.c b/src/lib/krb5/ccache/cc_kcm.c
index 772928e..1f81a21 100644
--- a/src/lib/krb5/ccache/cc_kcm.c
+++ b/src/lib/krb5/ccache/cc_kcm.c
@@ -110,6 +110,40 @@ map_invalid(krb5_error_code code)
         KRB5_KCM_MALFORMED_REPLY : code;
 }
 
+/*
+ * Map an MIT krb5 KRB5_TC flag word to the equivalent Heimdal flag word.  Note
+ * that there is no MIT krb5 equivalent for Heimdal's KRB5_TC_DONT_MATCH_REALM
+ * (which is like KRB5_TC_MATCH_SRV_NAMEONLY but also applies to the client
+ * principal) and no Heimdal equivalent for MIT krb5's KRB5_TC_SUPPORTED_KTYPES
+ * (which matches against enctypes from the krb5_context rather than the
+ * matching cred).
+ */
+static inline krb5_flags
+map_tcflags(krb5_flags mitflags)
+{
+    krb5_flags heimflags = 0;
+
+    if (mitflags & KRB5_TC_MATCH_TIMES)
+        heimflags |= KCM_TC_MATCH_TIMES;
+    if (mitflags & KRB5_TC_MATCH_IS_SKEY)
+        heimflags |= KCM_TC_MATCH_IS_SKEY;
+    if (mitflags & KRB5_TC_MATCH_FLAGS)
+        heimflags |= KCM_TC_MATCH_FLAGS;
+    if (mitflags & KRB5_TC_MATCH_TIMES_EXACT)
+        heimflags |= KCM_TC_MATCH_TIMES_EXACT;
+    if (mitflags & KRB5_TC_MATCH_FLAGS_EXACT)
+        heimflags |= KCM_TC_MATCH_FLAGS_EXACT;
+    if (mitflags & KRB5_TC_MATCH_AUTHDATA)
+        heimflags |= KCM_TC_MATCH_AUTHDATA;
+    if (mitflags & KRB5_TC_MATCH_SRV_NAMEONLY)
+        heimflags |= KCM_TC_MATCH_SRV_NAMEONLY;
+    if (mitflags & KRB5_TC_MATCH_2ND_TKT)
+        heimflags |= KCM_TC_MATCH_2ND_TKT;
+    if (mitflags & KRB5_TC_MATCH_KTYPE)
+        heimflags |= KCM_TC_MATCH_KEYTYPE;
+    return heimflags;
+}
+
 /* Begin a request for the given opcode.  If cache is non-null, supply the
  * cache name as a request parameter. */
 static void
@@ -936,7 +970,7 @@ kcm_remove_cred(krb5_context context, krb5_ccache cache, krb5_flags flags,
     struct kcmreq req;
 
     kcmreq_init(&req, KCM_OP_REMOVE_CRED, cache);
-    k5_buf_add_uint32_be(&req.reqbuf, flags);
+    k5_buf_add_uint32_be(&req.reqbuf, map_tcflags(flags));
     k5_marshal_mcred(&req.reqbuf, mcred);
     ret = cache_call(context, cache, &req);
     kcmreq_free(&req);