From patchwork Mon Dec 3 00:30:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 10708465 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2ECB713BB for ; Mon, 3 Dec 2018 00:32:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1E8F42A51E for ; Mon, 3 Dec 2018 00:32:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 12BBD2A54D; Mon, 3 Dec 2018 00:32:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 676652A51E for ; Mon, 3 Dec 2018 00:32:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725788AbeLCAcI (ORCPT ); Sun, 2 Dec 2018 19:32:08 -0500 Received: from mx2.suse.de ([195.135.220.15]:40780 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725785AbeLCAcI (ORCPT ); Sun, 2 Dec 2018 19:32:08 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 648BBAD90; Mon, 3 Dec 2018 00:32:02 +0000 (UTC) From: NeilBrown To: "J. Bruce Fields" , Chuck Lever , Jeff Layton , Trond Myklebust , Anna Schumaker Date: Mon, 03 Dec 2018 11:30:30 +1100 Subject: [PATCH 01/23] cred: add cred_fscmp() for comparing creds. Cc: Linux NFS Mailing List , linux-kernel@vger.kernel.org Message-ID: <154379703003.28598.12775774846678611265.stgit@noble> In-Reply-To: <154379689752.28598.6750646657534626618.stgit@noble> References: <154379689752.28598.6750646657534626618.stgit@noble> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP NFS needs to compare to credentials, to see if they can be treated the same w.r.t. filesystem access. Sometimes an ordering is needed when credentials are used as a key to an rbtree. NFS currently has its own private credential management from before 'struct cred' existed. To move it over to more consistent use of 'struct cred' we need a comparison function. This patch adds that function. Signed-off-by: NeilBrown --- include/linux/cred.h | 1 + kernel/cred.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 56 insertions(+) diff --git a/include/linux/cred.h b/include/linux/cred.h index 7eed6101c791..f1085767e1b3 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -169,6 +169,7 @@ extern int change_create_files_as(struct cred *, struct inode *); extern int set_security_override(struct cred *, u32); extern int set_security_override_from_ctx(struct cred *, const char *); extern int set_create_files_as(struct cred *, struct inode *); +extern int cred_fscmp(const struct cred *, const struct cred *); extern void __init cred_init(void); /* diff --git a/kernel/cred.c b/kernel/cred.c index ecf03657e71c..0b3ac72bd717 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -19,6 +19,7 @@ #include #include #include +#include #if 0 #define kdebug(FMT, ...) \ @@ -564,6 +565,60 @@ void revert_creds(const struct cred *old) } EXPORT_SYMBOL(revert_creds); +/** + * cred_fscmp - Compare two credentials with respect to filesystem access. + * @a: The first credential + * @b: The second credential + * + * cred_cmp() will return zero if both credentials have the same + * fsuid, fsgid, and supplementary groups. That is, if they will both + * provide the same access to files based on mode/uid/gid. + * If the credentials are different, then either -1 or 1 will + * be returned depending on whether @a comes before or after @b + * respectively in an arbitrary, but stable, ordering of credentials. + * + * Return: -1, 0, or 1 depending on comparison + */ +int cred_fscmp(const struct cred *a, const struct cred *b) +{ + struct group_info *ga, *gb; + int g; + + if (a == b) + return 0; + if (uid_lt(a->fsuid, b->fsuid)) + return -1; + if (uid_gt(a->fsuid, b->fsuid)) + return 1; + + if (gid_lt(a->fsgid, b->fsgid)) + return -1; + if (gid_gt(a->fsgid, b->fsgid)) + return 1; + + ga = a->group_info; + gb = b->group_info; + if (ga == gb) + return 0; + if (ga == NULL) + return -1; + if (gb == NULL) + return 1; + if (ga->ngroups < gb->ngroups) + return -1; + if (ga->ngroups > gb->ngroups) + return 1; + + for (g = 0; g < ga->ngroups; g++) { + if (gid_lt(ga->gid[g], gb->gid[g])) + return -1; + if (gid_gt(ga->gid[g], gb->gid[g])) + return 1; + } + return 0; +} +EXPORT_SYMBOL(cred_fscmp); + /* * initialise the credentials stuff */