From patchwork Fri Apr 22 19:58:33 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sachin Prabhu X-Patchwork-Id: 8915431 Return-Path: X-Original-To: patchwork-cifs-client@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 21C869F1D3 for ; Fri, 22 Apr 2016 19:58:39 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2337420221 for ; Fri, 22 Apr 2016 19:58:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA35320212 for ; Fri, 22 Apr 2016 19:58:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751363AbcDVT6g (ORCPT ); Fri, 22 Apr 2016 15:58:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49242 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751084AbcDVT6f (ORCPT ); Fri, 22 Apr 2016 15:58:35 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8C53F72D05 for ; Fri, 22 Apr 2016 19:58:34 +0000 (UTC) Received: from sprabhu-lp.hq.gsslab.rdu.redhat.com (unused [10.12.213.242] (may be forged)) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u3MJwXUx007375 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 22 Apr 2016 15:58:34 -0400 From: Sachin Prabhu To: linux-cifs Cc: David Howells , Scott Mayhew Subject: [PATCH] cifs: Create dedicated keyring for spnego operations Date: Fri, 22 Apr 2016 15:58:33 -0400 Message-Id: <1461355113-30510-1-git-send-email-sprabhu@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The session key is the default keyring set for request_key operations. This session key is revoked when the user owning the session logs out. Any long running daemon processes started by this session ends up with revoked session keyring which prevents these processes from using the request_key mechanism from obtaining the krb5 keys. The problem has been reported by a large number of autofs users. The problem is also seen with multiuser mounts where the share may be used by processes run by a user who has since logged out. A reproducer using automount is available on the Red Hat bz. The patch creates a new keyring which is used to cache cifs spnego upcalls. Red Hat bz: 1267754 Signed-off-by: Sachin Prabhu Reported-by: Scott Mayhew Reviewed-by: Shirish Pargaonkar --- fs/cifs/cifs_spnego.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++ fs/cifs/cifsfs.c | 4 +-- fs/cifs/cifsproto.h | 2 ++ 3 files changed, 71 insertions(+), 2 deletions(-) diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c index 6908080..248ab43 100644 --- a/fs/cifs/cifs_spnego.c +++ b/fs/cifs/cifs_spnego.c @@ -24,11 +24,14 @@ #include #include #include +#include #include #include "cifsglob.h" #include "cifs_spnego.h" #include "cifs_debug.h" +static const struct cred *spnego_cred; + /* create a new cifs key */ static int cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep) @@ -102,6 +105,7 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo) size_t desc_len; struct key *spnego_key; const char *hostname = server->hostname; + const struct cred *saved_cred; /* length of fields (with semicolons): ver=0xyz ip4=ipaddress host=hostname sec=mechanism uid=0xFF user=username */ @@ -163,7 +167,9 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo) sprintf(dp, ";pid=0x%x", current->pid); cifs_dbg(FYI, "key description = %s\n", description); + saved_cred = override_creds(spnego_cred); spnego_key = request_key(&cifs_spnego_key_type, description, ""); + revert_creds(saved_cred); #ifdef CONFIG_CIFS_DEBUG2 if (cifsFYI && !IS_ERR(spnego_key)) { @@ -177,3 +183,64 @@ out: kfree(description); return spnego_key; } + +int +init_cifs_spnego(void) +{ + struct cred *cred; + struct key *keyring; + int ret; + + cifs_dbg(FYI, "Registering the %s key type\n", + cifs_spnego_key_type.name); + + /* + * Create an override credential set with special thread keyring for + * spnego upcalls. + */ + + cred = prepare_kernel_cred(NULL); + if (!cred) + return -ENOMEM; + + keyring = keyring_alloc(".cifs_spnego", + GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred, + (KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW | KEY_USR_READ, + KEY_ALLOC_NOT_IN_QUOTA, NULL); + if (IS_ERR(keyring)) { + ret = PTR_ERR(keyring); + goto failed_put_cred; + } + + ret = register_key_type(&cifs_spnego_key_type); + if (ret < 0) + goto failed_put_key; + + /* + * instruct request_key() to use this special keyring as a cache for + * the results it looks up + */ + set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags); + cred->thread_keyring = keyring; + cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; + spnego_cred = cred; + + cifs_dbg(FYI, "cifs spnego keyring: %d\n", key_serial(keyring)); + return 0; + +failed_put_key: + key_put(keyring); +failed_put_cred: + put_cred(cred); + return ret; +} + +void +exit_cifs_spnego(void) +{ + key_revoke(spnego_cred->thread_keyring); + unregister_key_type(&cifs_spnego_key_type); + put_cred(spnego_cred); + cifs_dbg(FYI, "Unregistered %s key type\n", cifs_spnego_key_type.name); +} diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 8920156..9852044 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -1307,7 +1307,7 @@ init_cifs(void) goto out_destroy_mids; #ifdef CONFIG_CIFS_UPCALL - rc = register_key_type(&cifs_spnego_key_type); + rc = init_cifs_spnego(); if (rc) goto out_destroy_request_bufs; #endif /* CONFIG_CIFS_UPCALL */ @@ -1330,7 +1330,7 @@ out_init_cifs_idmap: out_register_key_type: #endif #ifdef CONFIG_CIFS_UPCALL - unregister_key_type(&cifs_spnego_key_type); + exit_cifs_spnego(); out_destroy_request_bufs: #endif cifs_destroy_request_bufs(); diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h index eed7ff5..ca618b0 100644 --- a/fs/cifs/cifsproto.h +++ b/fs/cifs/cifsproto.h @@ -60,6 +60,8 @@ do { \ } while (0) extern int init_cifs_idmap(void); extern void exit_cifs_idmap(void); +extern int init_cifs_spnego(void); +extern int exit_cifs_spnego(void); extern char *build_path_from_dentry(struct dentry *); extern char *cifs_build_path_to_root(struct smb_vol *vol, struct cifs_sb_info *cifs_sb,