From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C070C433EF for ; Thu, 18 Nov 2021 14:39:35 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B009461406 for ; Thu, 18 Nov 2021 14:39:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org B009461406 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:41292 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mniZZ-0002VW-UR for qemu-devel@archiver.kernel.org; Thu, 18 Nov 2021 09:39:33 -0500 Received: from eggs.gnu.org ([209.51.188.92]:46960) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mniWP-0004qc-IM for qemu-devel@nongnu.org; Thu, 18 Nov 2021 09:36:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:30078) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mniWN-0004mq-T2 for qemu-devel@nongnu.org; Thu, 18 Nov 2021 09:36:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637246175; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RLvn5axLfKncylepktKIonBhDChuf9AdJ2wVIfSEnAM=; b=a1z81l5+CJg8Ovfnf9Pm/D6rEZSt6O1HPtbzL6WXHc6EdEN33okbDGv763zPsewr2XLlJS vswDStlghRXxihYzKy5qxCpnoUNmUxobHFlVCG4zlIGieMkTkCQBBuIsrMNnWEWXiJL6hY o6V+P/xuDa3Jpx5zqyww9x3bTPqGp7c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-436-7KSAYSxrMKeCjGVMI_ByUg-1; Thu, 18 Nov 2021 09:36:13 -0500 X-MC-Unique: 7KSAYSxrMKeCjGVMI_ByUg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 000851B2C981; Thu, 18 Nov 2021 14:36:12 +0000 (UTC) Received: from localhost.localdomain.com (unknown [10.33.36.247]) by smtp.corp.redhat.com (Postfix) with ESMTP id 86D7C179B3; Thu, 18 Nov 2021 14:36:10 +0000 (UTC) From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= To: qemu-devel@nongnu.org Subject: [PATCH 3/3] block: print the server key type and fingerprint on failure Date: Thu, 18 Nov 2021 14:35:47 +0000 Message-Id: <20211118143547.2045554-4-berrange@redhat.com> In-Reply-To: <20211118143547.2045554-1-berrange@redhat.com> References: <20211118143547.2045554-1-berrange@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Hanna Reitz , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , "Richard W.M. Jones" , qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" When validating the server key fingerprint fails, it is difficult for the user to know what they got wrong. The fingerprint accepted by QEMU is received in a different format than openssh displays. There can also be keys for multiple different ciphers in known_hosts. It may not be obvious which cipher QEMU will use and whether it will be the same as openssh. Address this by printing the server key type and its corresponding fingerprint in the format QEMU accepts. Signed-off-by: Daniel P. Berrangé --- block/ssh.c | 37 ++++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-) diff --git a/block/ssh.c b/block/ssh.c index fcc0ab765a..967a2b971e 100644 --- a/block/ssh.c +++ b/block/ssh.c @@ -386,14 +386,28 @@ static int compare_fingerprint(const unsigned char *fingerprint, size_t len, return *host_key_check - '\0'; } +static char *format_fingerprint(const unsigned char *fingerprint, size_t len) +{ + static const char *hex = "0123456789abcdef"; + char *ret = g_new0(char, (len * 2) + 1); + for (size_t i = 0; i < len; i++) { + ret[i * 2] = hex[((fingerprint[i] >> 4) & 0xf)]; + ret[(i * 2) + 1] = hex[(fingerprint[i] & 0xf)]; + } + ret[len * 2] = '\0'; + return ret; +} + static int check_host_key_hash(BDRVSSHState *s, const char *hash, - enum ssh_publickey_hash_type type, Error **errp) + enum ssh_publickey_hash_type type, const char *typestr, + Error **errp) { int r; ssh_key pubkey; unsigned char *server_hash; size_t server_hash_len; + const char *keytype; r = ssh_get_server_publickey(s->session, &pubkey); if (r != SSH_OK) { @@ -401,6 +415,8 @@ check_host_key_hash(BDRVSSHState *s, const char *hash, return -EINVAL; } + keytype = ssh_key_type_to_char(ssh_key_type(pubkey)); + r = ssh_get_publickey_hash(pubkey, type, &server_hash, &server_hash_len); ssh_key_free(pubkey); if (r != 0) { @@ -410,12 +426,16 @@ check_host_key_hash(BDRVSSHState *s, const char *hash, } r = compare_fingerprint(server_hash, server_hash_len, hash); - ssh_clean_pubkey_hash(&server_hash); if (r != 0) { - error_setg(errp, "remote host key does not match host_key_check '%s'", - hash); + g_autofree char *server_fp = format_fingerprint(server_hash, + server_hash_len); + error_setg(errp, "remote host %s key fingerprint '%s:%s' " + "does not match host_key_check '%s:%s'", + keytype, typestr, server_fp, typestr, hash); + ssh_clean_pubkey_hash(&server_hash); return -EPERM; } + ssh_clean_pubkey_hash(&server_hash); return 0; } @@ -436,13 +456,16 @@ static int check_host_key(BDRVSSHState *s, SshHostKeyCheck *hkc, Error **errp) case SSH_HOST_KEY_CHECK_MODE_HASH: if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_MD5) { return check_host_key_hash(s, hkc->u.hash.hash, - SSH_PUBLICKEY_HASH_MD5, errp); + SSH_PUBLICKEY_HASH_MD5, "md5", + errp); } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA1) { return check_host_key_hash(s, hkc->u.hash.hash, - SSH_PUBLICKEY_HASH_SHA1, errp); + SSH_PUBLICKEY_HASH_SHA1, "sha1", + errp); } else if (hkc->u.hash.type == SSH_HOST_KEY_CHECK_HASH_TYPE_SHA256) { return check_host_key_hash(s, hkc->u.hash.hash, - SSH_PUBLICKEY_HASH_SHA256, errp); + SSH_PUBLICKEY_HASH_SHA256, "sha256", + errp); } g_assert_not_reached(); break; -- 2.31.1