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-rw-r--r--source4/heimdal/lib/krb5/crypto.c32
-rw-r--r--source4/heimdal/lib/krb5/pac.c81
2 files changed, 89 insertions, 24 deletions
diff --git a/source4/heimdal/lib/krb5/crypto.c b/source4/heimdal/lib/krb5/crypto.c
index 2502cc672f..006028b601 100644
--- a/source4/heimdal/lib/krb5/crypto.c
+++ b/source4/heimdal/lib/krb5/crypto.c
@@ -1496,6 +1496,8 @@ SP_HMAC_SHA1_checksum(krb5_context context,
/*
* checksum according to section 5. of draft-brezak-win2k-krb-rc4-hmac-03.txt
+ *
+ * This function made available to PAC routines
*/
static krb5_error_code
@@ -1547,6 +1549,36 @@ HMAC_MD5_checksum(krb5_context context,
return 0;
}
+/* HMAC-MD5 checksum over any key (needed for the PAC routines) */
+krb5_error_code
+HMAC_MD5_any_checksum(krb5_context context,
+ const krb5_keyblock *key,
+ const void *data,
+ size_t len,
+ unsigned usage,
+ Checksum *result)
+{
+ krb5_error_code ret;
+ struct key_data local_key;
+ ret = krb5_copy_keyblock(context, key, &local_key.key);
+ if (ret)
+ return ret;
+
+ local_key.schedule = NULL;
+ ret = krb5_data_alloc (&result->checksum, 16);
+ if (ret)
+ return ret;
+
+ result->cksumtype = CKSUMTYPE_HMAC_MD5;
+ ret = HMAC_MD5_checksum(context, &local_key, data, len, usage, result);
+
+ if (ret)
+ krb5_data_free(&result->checksum);
+
+ krb5_free_keyblock(context, local_key.key);
+ return ret;
+}
+
static struct checksum_type checksum_none = {
CKSUMTYPE_NONE,
"none",
diff --git a/source4/heimdal/lib/krb5/pac.c b/source4/heimdal/lib/krb5/pac.c
index b66e79960d..69d9879330 100644
--- a/source4/heimdal/lib/krb5/pac.c
+++ b/source4/heimdal/lib/krb5/pac.c
@@ -412,7 +412,6 @@ verify_checksum(krb5_context context,
void *ptr, size_t len,
const krb5_keyblock *key)
{
- krb5_crypto crypto = NULL;
krb5_storage *sp = NULL;
uint32_t type;
krb5_error_code ret;
@@ -452,14 +451,40 @@ verify_checksum(krb5_context context,
goto out;
}
- ret = krb5_crypto_init(context, key, 0, &crypto);
- if (ret)
- goto out;
+ /* If the checksum is HMAC-MD5, the checksum type is not tied to
+ * the key type, instead the HMAC-MD5 checksum is applied blindly
+ * on whatever key is used for this connection, avoiding issues
+ * with unkeyed checksums on des-cbc-md5 and des-cbc-crc. See
+ * http://comments.gmane.org/gmane.comp.encryption.kerberos.devel/8743
+ * for the same issue in MIT, and
+ * http://blogs.msdn.com/b/openspecification/archive/2010/01/01/verifying-the-server-signature-in-kerberos-privilege-account-certificate.aspx
+ * for Microsoft's explaination */
+ if (cksum.cksumtype == CKSUMTYPE_HMAC_MD5) {
+ Checksum local_checksum;
+
+ ret = HMAC_MD5_any_checksum(context, key, ptr, len, KRB5_KU_OTHER_CKSUM, &local_checksum);
+
+ if(local_checksum.checksum.length != cksum.checksum.length ||
+ ct_memcmp(local_checksum.checksum.data, cksum.checksum.data, local_checksum.checksum.length)) {
+ ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
+ krb5_set_error_message(context, ret,
+ N_("PAC integrity check failed for hmac-md5 checksum", ""));
+ } else {
+ ret = 0;
+ }
+ krb5_data_free(&local_checksum.checksum);
+ } else {
+ krb5_crypto crypto = NULL;
- ret = krb5_verify_checksum(context, crypto, KRB5_KU_OTHER_CKSUM,
- ptr, len, &cksum);
+ ret = krb5_crypto_init(context, key, 0, &crypto);
+ if (ret)
+ goto out;
+
+ ret = krb5_verify_checksum(context, crypto, KRB5_KU_OTHER_CKSUM,
+ ptr, len, &cksum);
+ krb5_crypto_destroy(context, crypto);
+ }
free(cksum.checksum.data);
- krb5_crypto_destroy(context, crypto);
krb5_storage_free(sp);
return ret;
@@ -469,14 +494,13 @@ out:
free(cksum.checksum.data);
if (sp)
krb5_storage_free(sp);
- if (crypto)
- krb5_crypto_destroy(context, crypto);
return ret;
}
static krb5_error_code
create_checksum(krb5_context context,
const krb5_keyblock *key,
+ uint32_t cksumtype,
void *data, size_t datalen,
void *sig, size_t siglen)
{
@@ -484,16 +508,27 @@ create_checksum(krb5_context context,
krb5_error_code ret;
Checksum cksum;
- ret = krb5_crypto_init(context, key, 0, &crypto);
- if (ret)
- return ret;
-
- ret = krb5_create_checksum(context, crypto, KRB5_KU_OTHER_CKSUM, 0,
- data, datalen, &cksum);
- krb5_crypto_destroy(context, crypto);
- if (ret)
- return ret;
+ /* If the checksum is HMAC-MD5, the checksum type is not tied to
+ * the key type, instead the HMAC-MD5 checksum is applied blindly
+ * on whatever key is used for this connection, avoiding issues
+ * with unkeyed checksums on des-cbc-md5 and des-cbc-crc. See
+ * http://comments.gmane.org/gmane.comp.encryption.kerberos.devel/8743
+ * for the same issue in MIT, and
+ * http://blogs.msdn.com/b/openspecification/archive/2010/01/01/verifying-the-server-signature-in-kerberos-privilege-account-certificate.aspx
+ * for Microsoft's explaination */
+ if (cksumtype == CKSUMTYPE_HMAC_MD5) {
+ ret = HMAC_MD5_any_checksum(context, key, data, datalen, KRB5_KU_OTHER_CKSUM, &cksum);
+ } else {
+ ret = krb5_crypto_init(context, key, 0, &crypto);
+ if (ret)
+ return ret;
+ ret = krb5_create_checksum(context, crypto, KRB5_KU_OTHER_CKSUM, 0,
+ data, datalen, &cksum);
+ krb5_crypto_destroy(context, crypto);
+ if (ret)
+ return ret;
+ }
if (cksum.checksum.length != siglen) {
krb5_set_error_message(context, EINVAL, "pac checksum wrong length");
free_Checksum(&cksum);
@@ -845,8 +880,8 @@ pac_checksum(krb5_context context,
return ret;
if (krb5_checksum_is_keyed(context, cktype) == FALSE) {
- krb5_set_error_message(context, EINVAL, "PAC checksum type is not keyed");
- return EINVAL;
+ *cksumtype = CKSUMTYPE_HMAC_MD5;
+ *cksumsize = 16;
}
ret = krb5_checksumsize(context, cktype, cksumsize);
@@ -1026,16 +1061,14 @@ _krb5_pac_sign(krb5_context context,
}
/* sign */
-
- ret = create_checksum(context, server_key,
+ ret = create_checksum(context, server_key, server_cksumtype,
d.data, d.length,
(char *)d.data + server_offset, server_size);
if (ret) {
krb5_data_free(&d);
goto out;
}
-
- ret = create_checksum(context, priv_key,
+ ret = create_checksum(context, priv_key, priv_cksumtype,
(char *)d.data + server_offset, server_size,
(char *)d.data + priv_offset, priv_size);
if (ret) {
generated by cgit (git 2.34.1) at 2024-11-02 12:40:19 +0000