Always include salt in LDAP KrbKey encoding

In the LDAP KDB module, ensure that every krb5_key_data we pass to
asn1_encode_sequence_of_keys includes a salt type, for compatibility
with the decoder in unpatched krb5 1.11 and 1.12.

This is not a behavior change by itself; since 1.7 the encoder has
always included a KrbKey salt field because it erroneously treats that
field as non-optional.  (Luckily, the encoded salt always happens to
have salt type 0 because krb5_key_data constructors start with zeroed
memory.)  The next commit will fix the encoder and decoder to properly
treat the KrbKey salt field as optional, so we need this change to
ensure that our encodings remain compatible.

Also fix the ASN.1 tests to set key_data_ver correctly for the sample
test key data.

(cherry picked from commit 1825455ede7e61ab934b16262fb5b12b78a52f1a)

ticket: 8102 (new)
version_fixed: 1.11.6
status: resolved

2 files changed, 21 insertions, 1 deletions

diff --git a/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c b/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
index a7101a7..6ea9a98 100644
--- a/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
+++ b/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
@@ -407,17 +407,35 @@ asn1_decode_sequence_of_keys(krb5_data *in, krb5_key_data **out,
 
 /* Decoding ASN.1 encoded key */
 static struct berval **
-krb5_encode_krbsecretkey(krb5_key_data *key_data, int n_key_data,
+krb5_encode_krbsecretkey(krb5_key_data *key_data_in, int n_key_data,
                          krb5_kvno mkvno) {
     struct berval **ret = NULL;
     int currkvno;
     int num_versions = 1;
     int i, j, last;
     krb5_error_code err = 0;
+    krb5_key_data *key_data;
 
     if (n_key_data <= 0)
         return NULL;
 
+    /* Make a shallow copy of the key data so we can alter it. */
+    key_data = k5calloc(n_key_data, sizeof(*key_data), &err);
+    if (key_data_in == NULL)
+        goto cleanup;
+    memcpy(key_data, key_data_in, n_key_data * sizeof(*key_data));
+
+    /* Unpatched krb5 1.11 and 1.12 cannot decode KrbKey sequences with no salt
+     * field.  For compatibility, always encode a salt field. */
+    for (i = 0; i < n_key_data; i++) {
+        if (key_data[i].key_data_ver == 1) {
+            key_data[i].key_data_ver = 2;
+            key_data[i].key_data_type[1] = KRB5_KDB_SALTTYPE_NORMAL;
+            key_data[i].key_data_length[1] = 0;
+            key_data[i].key_data_contents[1] = NULL;
+        }
+    }
+
     /* Find the number of key versions */
     for (i = 0; i < n_key_data - 1; i++)
         if (key_data[i].key_data_kvno != key_data[i + 1].key_data_kvno)
@@ -453,6 +471,7 @@ krb5_encode_krbsecretkey(krb5_key_data *key_data, int n_key_data,
 
 cleanup:
 
+    free(key_data);
     if (err != 0) {
         if (ret != NULL) {
             for (i = 0; i <= num_versions; i++)
diff --git a/src/tests/asn.1/ktest.c b/src/tests/asn.1/ktest.c
index e734aeb..86fcfdb 100644
--- a/src/tests/asn.1/ktest.c
+++ b/src/tests/asn.1/ktest.c
@@ -908,6 +908,7 @@ ktest_make_sample_key_data(krb5_key_data *p, int i)
     len = asprintf(&str, "key%d", i);
     if (len < 0)
         abort();
+    p->key_data_ver = 2;
     p->key_data_type[0] = 2;
     p->key_data_length[0] = (unsigned int) len;
     p->key_data_contents[0] = (krb5_octet *)str;