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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2871C4332F for ; Tue, 18 Oct 2022 12:00:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230391AbiJRMA3 (ORCPT ); Tue, 18 Oct 2022 08:00:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230338AbiJRL7O (ORCPT ); Tue, 18 Oct 2022 07:59:14 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 888E4BE2E0; Tue, 18 Oct 2022 04:58:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 253F861070; Tue, 18 Oct 2022 11:58:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A7FFC433C1; Tue, 18 Oct 2022 11:58:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666094296; bh=FRKf+wPuvDpHUPzkkOhMa1yAW2aXjGP89RAMXsyPeP0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ISjD5Q8prmAVSSJaDiKfRGd/PNxZy6xdj4e02NEnlNIS02ehqYRfnoF3hgJ1urs+v 2hHhORUqtLrtuOfqXcDRhTvEgXVjcu6mlGSMSJ27ULrfsbWh2R1CBQ2g1/H75X9LqD 9uNwsMwtft37h1e/RntxlNJwbGrW6nzAvz41BLF53v04zJyXt0htrem0L0GsT5IqX0 UlGlnqBA8TueLG5kv44UQp8AnPdXx0PLfCge5RsyEjsQ97FZbYr90PZVxUjQbvPdT3 LolzoXHao2KNtYX16oZSpHyj4VhFCoO5+PfRReFd3OGLpdy+da7ZCJ4u1ndmPNjxe6 oBwznM6qDGhGQ== From: Christian Brauner To: linux-fsdevel@vger.kernel.org Cc: Christian Brauner , Seth Forshee , Christoph Hellwig , Al Viro , Miklos Szeredi , Amir Goldstein , linux-unionfs@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v5 22/30] ovl: implement set acl method Date: Tue, 18 Oct 2022 13:56:52 +0200 Message-Id: <20221018115700.166010-23-brauner@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221018115700.166010-1-brauner@kernel.org> References: <20221018115700.166010-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7601; i=brauner@kernel.org; h=from:subject; bh=FRKf+wPuvDpHUPzkkOhMa1yAW2aXjGP89RAMXsyPeP0=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMST7TdG80v+w3+jms6lnvuvH9Nj0rFpmJsgRtqhebsrJpL5v sZ12HaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABMR4GD4nxzopBRat46pyOfdxNfnQp bbL848+JZpm75Yhr3AjGd5dxn+p3+WmOq9apUDT8mJVa5hnV8qv/nM3ZOkcllYTqyfKYaHBwA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. In order to build a type safe posix api around get and set acl we need all filesystem to implement get and set acl. Now that we have added get and set acl inode operations that allow easy access to the dentry we give overlayfs it's own get and set acl inode operations. The set acl inode operation is duplicates most of the ovl posix acl xattr handler. The main difference being that the set acl inode operation relies on the new posix acl api. Once the vfs has been switched over the custom posix acl xattr handler will be removed completely. Note, until the vfs has been switched to the new posix acl api this patch is a non-functional change. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Signed-off-by: Christian Brauner (Microsoft) Acked-by: Miklos Szeredi --- Notes: /* v2 */ Miklos Szeredi : - split ovl_set_acl() into two functions - add comment about checking whether copy up is even necessary /* v3 */ unchanged /* v4 */ unchanged /* v5 */ unchanged fs/overlayfs/dir.c | 1 + fs/overlayfs/inode.c | 94 ++++++++++++++++++++++++++++++++++++++++ fs/overlayfs/overlayfs.h | 17 ++++++++ 3 files changed, 112 insertions(+) diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index eb49d5d7b56f..0e817ebce92c 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -1313,6 +1313,7 @@ const struct inode_operations ovl_dir_inode_operations = { .listxattr = ovl_listxattr, .get_inode_acl = ovl_get_inode_acl, .get_acl = ovl_get_acl, + .set_acl = ovl_set_acl, .update_time = ovl_update_time, .fileattr_get = ovl_fileattr_get, .fileattr_set = ovl_fileattr_set, diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 74edbd1c1159..304a6dbb852a 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -592,6 +592,98 @@ struct posix_acl *do_ovl_get_acl(struct user_namespace *mnt_userns, return acl; } + +static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode, + struct posix_acl *acl, int type) +{ + int err; + struct path realpath; + const char *acl_name; + const struct cred *old_cred; + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct dentry *upperdentry = ovl_dentry_upper(dentry); + struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); + + err = ovl_want_write(dentry); + if (err) + return err; + + /* + * If ACL is to be removed from a lower file, check if it exists in + * the first place before copying it up. + */ + acl_name = posix_acl_xattr_name(type); + if (!acl && !upperdentry) { + struct posix_acl *real_acl; + + ovl_path_lower(dentry, &realpath); + old_cred = ovl_override_creds(dentry->d_sb); + real_acl = vfs_get_acl(mnt_user_ns(realpath.mnt), realdentry, + acl_name); + revert_creds(old_cred); + posix_acl_release(real_acl); + if (IS_ERR(real_acl)) { + err = PTR_ERR(real_acl); + goto out_drop_write; + } + } + + if (!upperdentry) { + err = ovl_copy_up(dentry); + if (err) + goto out_drop_write; + + realdentry = ovl_dentry_upper(dentry); + } + + old_cred = ovl_override_creds(dentry->d_sb); + if (acl) + err = ovl_do_set_acl(ofs, realdentry, acl_name, acl); + else + err = ovl_do_remove_acl(ofs, realdentry, acl_name); + revert_creds(old_cred); + + /* copy c/mtime */ + ovl_copyattr(inode); + +out_drop_write: + ovl_drop_write(dentry); + return err; +} + +int ovl_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, + struct posix_acl *acl, int type) +{ + int err; + struct inode *inode = d_inode(dentry); + struct dentry *workdir = ovl_workdir(dentry); + struct inode *realinode = ovl_inode_real(inode); + + if (!IS_POSIXACL(d_inode(workdir))) + return -EOPNOTSUPP; + if (!realinode->i_op->set_acl) + return -EOPNOTSUPP; + if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) + return acl ? -EACCES : 0; + if (!inode_owner_or_capable(&init_user_ns, inode)) + return -EPERM; + + /* + * Check if sgid bit needs to be cleared (actual setacl operation will + * be done with mounter's capabilities and so that won't do it for us). + */ + if (unlikely(inode->i_mode & S_ISGID) && type == ACL_TYPE_ACCESS && + !in_group_p(inode->i_gid) && + !capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_FSETID)) { + struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; + + err = ovl_setattr(&init_user_ns, dentry, &iattr); + if (err) + return err; + } + + return ovl_set_or_remove_acl(dentry, inode, acl, type); +} #endif int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags) @@ -768,6 +860,7 @@ static const struct inode_operations ovl_file_inode_operations = { .listxattr = ovl_listxattr, .get_inode_acl = ovl_get_inode_acl, .get_acl = ovl_get_acl, + .set_acl = ovl_set_acl, .update_time = ovl_update_time, .fiemap = ovl_fiemap, .fileattr_get = ovl_fileattr_get, @@ -789,6 +882,7 @@ static const struct inode_operations ovl_special_inode_operations = { .listxattr = ovl_listxattr, .get_inode_acl = ovl_get_inode_acl, .get_acl = ovl_get_acl, + .set_acl = ovl_set_acl, .update_time = ovl_update_time, }; diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index d334977030c8..ab5061c9aa2a 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -8,6 +8,8 @@ #include #include #include +#include +#include #include "ovl_entry.h" #undef pr_fmt @@ -278,6 +280,18 @@ static inline int ovl_removexattr(struct ovl_fs *ofs, struct dentry *dentry, return ovl_do_removexattr(ofs, dentry, ovl_xattr(ofs, ox)); } +static inline int ovl_do_set_acl(struct ovl_fs *ofs, struct dentry *dentry, + const char *acl_name, struct posix_acl *acl) +{ + return vfs_set_acl(ovl_upper_mnt_userns(ofs), dentry, acl_name, acl); +} + +static inline int ovl_do_remove_acl(struct ovl_fs *ofs, struct dentry *dentry, + const char *acl_name) +{ + return vfs_remove_acl(ovl_upper_mnt_userns(ofs), dentry, acl_name); +} + static inline int ovl_do_rename(struct ovl_fs *ofs, struct inode *olddir, struct dentry *olddentry, struct inode *newdir, struct dentry *newdentry, unsigned int flags) @@ -607,9 +621,12 @@ static inline struct posix_acl *ovl_get_acl(struct user_namespace *mnt_userns, { return do_ovl_get_acl(mnt_userns, d_inode(dentry), type, false, false); } +int ovl_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry, + struct posix_acl *acl, int type); #else #define ovl_get_inode_acl NULL #define ovl_get_acl NULL +#define ovl_set_acl NULL #endif int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags); -- 2.34.1