Attachment 5986 Details for Bug 35287

[patch] 0001-s4-backupkey-Ensure-RSA-modulus-is-2048-bits.patch

0001-s4-backupkey-Ensure-RSA-modulus-is-2048-bits.patch (text/plain), 2.18 KB, created by Arvid Requate on 2014-07-07 19:49 CEST

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Creator: Arvid Requate

Created: 2014-07-07 19:49 CEST

Size: 2.18 KB

patch

obsolete

>From 1f49bf1531935a28147afe0cae4f2298e809fa0b Mon Sep 17 00:00:00 2001
>From: Arvid Requate <requate@univention.de>
>Date: Mon, 7 Jul 2014 17:39:51 +0200
>Subject: [PATCH 01/10] s4-backupkey: Ensure RSA modulus is 2048 bits
>
>RSA_generate_key_ex doesn't always generate a modulus of requested
>bit length. Tests with Windows 7 clients showed that they decline
>x509 certificates (MS-BKRP 2.2.1) in cases where the modulus length
>is smaller than the specified 2048 bits. For the user this resulted
>in DPAPI failing to retrieve stored credentials after the user password
>has been changed at least two times. On the server side log.samba showed
>that the client also called the as yet unlimplemented ServerWrap sub-
>protocol function BACKUPKEY_BACKUP_KEY_GUID after it had called the
>ClientWarp function BACKUPKEY_RETRIEVE_BACKUP_KEY_GUID. After
>enabling DPAPI auditing on the Windows Clients the Event Viewer showed
>Event-ID 4692 failing with a FailureReason value of 0x7a in these cases.
>
>Signed-off-by: Arvid Requate <requate@univention.de>
>---
> source4/rpc_server/backupkey/dcesrv_backupkey.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
>diff --git a/source4/rpc_server/backupkey/dcesrv_backupkey.c b/source4/rpc_server/backupkey/dcesrv_backupkey.c
>index 87799db..765caeb 100644
>--- a/source4/rpc_server/backupkey/dcesrv_backupkey.c
>+++ b/source4/rpc_server/backupkey/dcesrv_backupkey.c
>@@ -759,6 +759,7 @@ static WERROR create_heimdal_rsa_key(TALLOC_CTX *ctx, hx509_context *hctx,
> 	uint8_t *p0, *p;
> 	size_t len;
> 	int bits = 2048;
>+	int RSA_returned_bits;
> 
> 	*_rsa = NULL;
> 
>@@ -776,11 +777,15 @@ static WERROR create_heimdal_rsa_key(TALLOC_CTX *ctx, hx509_context *hctx,
> 		return WERR_INTERNAL_ERROR;
> 	}
> 
>-	ret = RSA_generate_key_ex(rsa, bits, pub_expo, NULL);
>-	if(ret != 1) {
>-		RSA_free(rsa);
>-		BN_free(pub_expo);
>-		return WERR_INTERNAL_ERROR;
>+	while (RSA_returned_bits != bits) {
>+		ret = RSA_generate_key_ex(rsa, bits, pub_expo, NULL);
>+		if(ret != 1) {
>+			RSA_free(rsa);
>+			BN_free(pub_expo);
>+			return WERR_INTERNAL_ERROR;
>+		}
>+		RSA_returned_bits = BN_num_bits(rsa->n);
>+		DEBUG(6, ("RSA_generate_key_ex returned %d Bits\n", RSA_returned_bits));
> 	}
> 	BN_free(pub_expo);
> 
>-- 
>2.0.0.rc2
>

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