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6cd4d4e8b6
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. So far 9p implemented a ->get_inode_acl() operation that didn't require access to the dentry in order to allow (limited) permission checking via posix acls in the vfs. Now that we have get and set acl inode operations that take a dentry argument we can give 9p get and set acl inode operations. This is mostly a refactoring of the codepaths currently used in 9p posix acl xattr handler. After we have fully implemented the posix acl api and switched the vfs over to it, the 9p specific posix acl xattr handler and associated code will be removed. 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) <brauner@kernel.org>
79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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File: linux/posix_acl_xattr.h
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Extended attribute system call representation of Access Control Lists.
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Copyright (C) 2000 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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Copyright (C) 2002 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
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*/
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#ifndef _POSIX_ACL_XATTR_H
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#define _POSIX_ACL_XATTR_H
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#include <uapi/linux/xattr.h>
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#include <uapi/linux/posix_acl_xattr.h>
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#include <linux/posix_acl.h>
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static inline size_t
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posix_acl_xattr_size(int count)
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{
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return (sizeof(struct posix_acl_xattr_header) +
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(count * sizeof(struct posix_acl_xattr_entry)));
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}
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static inline int
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posix_acl_xattr_count(size_t size)
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{
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if (size < sizeof(struct posix_acl_xattr_header))
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return -1;
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size -= sizeof(struct posix_acl_xattr_header);
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if (size % sizeof(struct posix_acl_xattr_entry))
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return -1;
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return size / sizeof(struct posix_acl_xattr_entry);
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}
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#ifdef CONFIG_FS_POSIX_ACL
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void posix_acl_fix_xattr_from_user(void *value, size_t size);
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void posix_acl_fix_xattr_to_user(void *value, size_t size);
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void posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
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const struct inode *inode,
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void *value, size_t size);
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#else
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static inline void posix_acl_fix_xattr_from_user(void *value, size_t size)
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{
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}
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static inline void posix_acl_fix_xattr_to_user(void *value, size_t size)
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{
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}
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static inline void
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posix_acl_getxattr_idmapped_mnt(struct user_namespace *mnt_userns,
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const struct inode *inode, void *value,
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size_t size)
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{
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}
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#endif
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struct posix_acl *posix_acl_from_xattr(struct user_namespace *user_ns,
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const void *value, size_t size);
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int posix_acl_to_xattr(struct user_namespace *user_ns,
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const struct posix_acl *acl, void *buffer, size_t size);
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struct posix_acl *vfs_set_acl_prepare(struct user_namespace *mnt_userns,
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struct user_namespace *fs_userns,
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const void *value, size_t size);
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static inline const char *posix_acl_xattr_name(int type)
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{
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switch (type) {
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case ACL_TYPE_ACCESS:
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return XATTR_NAME_POSIX_ACL_ACCESS;
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case ACL_TYPE_DEFAULT:
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return XATTR_NAME_POSIX_ACL_DEFAULT;
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}
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return "";
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}
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extern const struct xattr_handler posix_acl_access_xattr_handler;
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extern const struct xattr_handler posix_acl_default_xattr_handler;
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#endif /* _POSIX_ACL_XATTR_H */
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