From patchwork Mon May 30 08:57:32 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Gruenbacher X-Patchwork-Id: 9140641 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 565CC60801 for ; Mon, 30 May 2016 08:59:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4643528212 for ; Mon, 30 May 2016 08:59:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 358A527BEF; Mon, 30 May 2016 08:59:53 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable 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 443B427BEF for ; Mon, 30 May 2016 08:59:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754489AbcE3I7r (ORCPT ); Mon, 30 May 2016 04:59:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41328 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754481AbcE3I7p (ORCPT ); Mon, 30 May 2016 04:59:45 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (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 86EE785367; Mon, 30 May 2016 08:59:44 +0000 (UTC) Received: from nux.redhat.com (vpn1-6-85.ams2.redhat.com [10.36.6.85]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u4U8vYAt026102; Mon, 30 May 2016 04:59:37 -0400 From: Andreas Gruenbacher To: Alexander Viro Cc: Andreas Gruenbacher , linux-fsdevel@vger.kernel.org, Tyler Hicks , ecryptfs@vger.kernel.org, Miklos Szeredi , linux-unionfs@vger.kernel.org, Mimi Zohar , linux-ima-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, David Howells , Serge Hallyn , Dmitry Kasatkin , Paul Moore , Stephen Smalley , Eric Paris , Casey Schaufler , Oleg Drokin , Andreas Dilger Subject: [PATCH v3 16/17] xattr: Stop calling {get, set, remove}xattr inode operations Date: Mon, 30 May 2016 10:57:32 +0200 Message-Id: <1464598653-3656-17-git-send-email-agruenba@redhat.com> In-Reply-To: <1464598653-3656-1-git-send-email-agruenba@redhat.com> References: <1464598653-3656-1-git-send-email-agruenba@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 30 May 2016 08:59:44 +0000 (UTC) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP All filesystems that support xattrs by now do so via xattr handlers. They all define sb->s_xattr, and their getxattr, setxattr, and removexattr inode operations use the generic inode operations. On filesystems that don't support xattrs, the xattr inode operations are all NULL, and sb->s_xattr is also NULL. This means that we can remove the getxattr, setxattr, and removexattr inode operations and directly call the generic handlers, or better, inline expand those handlers into fs/xattr.c. Filesystems that do not support xattrs on some inodes should clear the IOP_XATTR i_opflags flag in those inodes. (Right now, some filesystems have checks to disable xattrs on some inodes in the ->list, ->get, and ->set xattr handler operations instead.) The IOP_XATTR flag is automatically cleared in inodes of filesystems that don't have xattr support. Signed-off-by: Andreas Gruenbacher --- Documentation/filesystems/Locking | 24 +++++++++++++----- Documentation/filesystems/vfs.txt | 45 ++++++++++++++++++++++----------- fs/xattr.c | 52 +++++++++++++++++++++++++-------------- 3 files changed, 82 insertions(+), 39 deletions(-) diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index 75eea7c..b958926 100644 --- a/Documentation/filesystems/Locking +++ b/Documentation/filesystems/Locking @@ -56,10 +56,7 @@ prototypes: int (*get_acl)(struct inode *, int); int (*setattr) (struct dentry *, struct iattr *); int (*getattr) (struct vfsmount *, struct dentry *, struct kstat *); - int (*setxattr) (struct dentry *, const char *,const void *,size_t,int); - ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t); ssize_t (*listxattr) (struct dentry *, char *, size_t); - int (*removexattr) (struct dentry *, const char *); int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start, u64 len); void (*update_time)(struct inode *, struct timespec *, int); int (*atomic_open)(struct inode *, struct dentry *, @@ -87,16 +84,14 @@ setattr: yes permission: no (may not block if called in rcu-walk mode) get_acl: no getattr: no -setxattr: yes -getxattr: no listxattr: no -removexattr: yes fiemap: no update_time: no atomic_open: yes tmpfile: no dentry_open: no + Additionally, ->rmdir(), ->unlink() and ->rename() have ->i_mutex on victim. cross-directory ->rename() and rename2() has (per-superblock) @@ -105,6 +100,23 @@ victim. See Documentation/filesystems/directory-locking for more detailed discussion of the locking scheme for directory operations. +----------------------- xattr_handler operations ----------------------- +protoypes: + bool (*list)(struct dentry *dentry); + int (*get)(const struct xattr_handler *handler, struct dentry *dentry, + struct inode *inode, const char *name, void *buffer, + size_t size); + int (*set)(const struct xattr_handler *handler, struct dentry *dentry, + struct inode *inode, const char *name, const void *buffer, + size_t size, int flags); + +locking rules: + all may block + i_mutex(inode) +list: no +get: no +set: yes + --------------------------- super_operations --------------------------- prototypes: struct inode *(*alloc_inode)(struct super_block *sb); diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index c61a223..65988f7 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -323,6 +323,35 @@ Whoever sets up the inode is responsible for filling in the "i_op" field. This is a pointer to a "struct inode_operations" which describes the methods that can be performed on individual inodes. +struct xattr_handlers +--------------------- + +On filesystems that support extended attributes (xattrs), the s_xattr +superblock field points to a NULL-terminated array of xattr handlers. Extended +attributes are name:value pairs. + + name: Indicates that the handler matches attributes with the specified name + (such as "system.posix_acl_access"); the prefix field must be NULL. + + prefix: Indicates that the handler matches all attributes with the specified + name prefix (such as "user."); the name field must be NULL. + + list: Determine if attributes matching this xattr handler should be listed + for a particular dentry. Used by some listxattr implementations like + generic_listxattr. + + get: Called by the VFS to get the value of a particular extended attribute. + This method is called by the getxattr(2) system call. + + set: Called by the VFS to set the value of a particular extended attribute. + When the new value is NULL, called to remove a particular extended + attribute. This method is called by the the setxattr(2) and + removexattr(2) system calls. + +When none of the xattr handlers of a filesystem match the specified attribute +name or when a filesystem doesn't support extended attributes, the various +*xattr(2) system calls return -EOPNOTSUPP. + The Inode Object ================ @@ -356,10 +385,7 @@ struct inode_operations { int (*get_acl)(struct inode *, int); int (*setattr) (struct dentry *, struct iattr *); int (*getattr) (struct vfsmount *mnt, struct dentry *, struct kstat *); - int (*setxattr) (struct dentry *, const char *,const void *,size_t,int); - ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t); ssize_t (*listxattr) (struct dentry *, char *, size_t); - int (*removexattr) (struct dentry *, const char *); void (*update_time)(struct inode *, struct timespec *, int); int (*atomic_open)(struct inode *, struct dentry *, struct file *, unsigned open_flag, umode_t create_mode, int *opened); @@ -464,19 +490,8 @@ otherwise noted. getattr: called by the VFS to get attributes of a file. This method is called by stat(2) and related system calls. - setxattr: called by the VFS to set an extended attribute for a file. - Extended attribute is a name:value pair associated with an - inode. This method is called by setxattr(2) system call. - - getxattr: called by the VFS to retrieve the value of an extended - attribute name. This method is called by getxattr(2) function - call. - listxattr: called by the VFS to list all extended attributes for a - given file. This method is called by listxattr(2) system call. - - removexattr: called by the VFS to remove an extended attribute from - a file. This method is called by removexattr(2) system call. + given file. This method is called by the listxattr(2) system call. update_time: called by the VFS to update a specific time or the i_version of an inode. If this is not defined the VFS will update the inode itself diff --git a/fs/xattr.c b/fs/xattr.c index 8ffc93e..5bda06c 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -36,12 +36,9 @@ strcmp_prefix(const char *a, const char *a_prefix) /* * In order to implement different sets of xattr operations for each xattr - * prefix with the generic xattr API, a filesystem should create a - * null-terminated array of struct xattr_handler (one for each prefix) and - * hang a pointer to it off of the s_xattr field of the superblock. - * - * The generic_fooxattr() functions will use this list to dispatch xattr - * operations to the correct xattr_handler. + * prefix, a filesystem should create a null-terminated array of struct + * xattr_handler (one for each prefix) and hang a pointer to it off of the + * s_xattr field of the superblock. */ #define for_each_xattr_handler(handlers, handler) \ if (handlers) \ @@ -133,9 +130,16 @@ int __vfs_setxattr(struct dentry *dentry, struct inode *inode, const char *name, const void *value, size_t size, int flags) { - if (!inode->i_op->setxattr) + const struct xattr_handler *handler; + + handler = xattr_resolve_name(inode, &name); + if (IS_ERR(handler)) + return PTR_ERR(handler); + if (!handler->set) return -EOPNOTSUPP; - return inode->i_op->setxattr(dentry, inode, name, value, size, flags); + if (size == 0) + value = ""; /* empty EA, do not remove */ + return handler->set(handler, dentry, inode, name, value, size, flags); } EXPORT_SYMBOL(__vfs_setxattr); @@ -165,7 +169,7 @@ int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, if (issec) inode->i_flags &= ~S_NOSEC; - if (inode->i_op->setxattr) { + if (inode->i_opflags & IOP_XATTR) { error = __vfs_setxattr(dentry, inode, name, value, size, flags); if (!error) { fsnotify_xattr(dentry); @@ -250,6 +254,7 @@ ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, size_t xattr_size, gfp_t flags) { + const struct xattr_handler *handler; struct inode *inode = dentry->d_inode; char *value = *xattr_value; int error; @@ -258,10 +263,12 @@ vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, if (error) return error; - if (!inode->i_op->getxattr) + handler = xattr_resolve_name(inode, &name); + if (IS_ERR(handler)) + return PTR_ERR(handler); + if (!handler->get) return -EOPNOTSUPP; - - error = inode->i_op->getxattr(dentry, inode, name, NULL, 0); + error = handler->get(handler, dentry, inode, name, NULL, 0); if (error < 0) return error; @@ -272,7 +279,7 @@ vfs_getxattr_alloc(struct dentry *dentry, const char *name, char **xattr_value, memset(value, 0, error + 1); } - error = inode->i_op->getxattr(dentry, inode, name, value, error); + error = handler->get(handler, dentry, inode, name, value, error); *xattr_value = value; return error; } @@ -281,9 +288,14 @@ ssize_t __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name, void *value, size_t size) { - if (!inode->i_op->getxattr) + const struct xattr_handler *handler; + + handler = xattr_resolve_name(inode, &name); + if (IS_ERR(handler)) + return PTR_ERR(handler); + if (!handler->get) return -EOPNOTSUPP; - return inode->i_op->getxattr(dentry, inode, name, value, size); + return handler->get(handler, dentry, inode, name, value, size); } EXPORT_SYMBOL(__vfs_getxattr); @@ -342,11 +354,15 @@ EXPORT_SYMBOL_GPL(vfs_listxattr); int __vfs_removexattr(struct dentry *dentry, const char *name) { - struct inode *inode = dentry->d_inode; + struct inode *inode = d_inode(dentry); + const struct xattr_handler *handler; - if (!inode->i_op->removexattr) + handler = xattr_resolve_name(inode, &name); + if (IS_ERR(handler)) + return PTR_ERR(handler); + if (!handler->set) return -EOPNOTSUPP; - return inode->i_op->removexattr(dentry, name); + return handler->set(handler, dentry, inode, name, NULL, 0, XATTR_REPLACE); } EXPORT_SYMBOL(__vfs_removexattr);