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![Hugh Dickins](/assets/img/avatar_default.png)
Enable "user." extended attributes on tmpfs, limiting them by tracking the space they occupy, and deducting that space from the limited ispace (unless tmpfs mounted with nr_inodes=0 to leave that ispace unlimited). tmpfs inodes and simple xattrs are both unswappable, and have to be in lowmem on a 32-bit highmem kernel: so the ispace limit is appropriate for xattrs, without any need for a further mount option. Add simple_xattr_space() to give approximate but deterministic estimate of the space taken up by each xattr: with simple_xattrs_free() outputting the space freed if required (but kernfs and even some tmpfs usages do not require that, so don't waste time on strlen'ing if not needed). Security and trusted xattrs were already supported: for consistency and simplicity, account them from the same pool; though there's a small risk that a tmpfs with enough space before would now be considered too small. When extended attributes are used, "df -i" does show more IUsed and less IFree than can be explained by the inodes: document that (manpage later). xfstests tests/generic which were not run on tmpfs before but now pass: 020 037 062 070 077 097 103 117 337 377 454 486 523 533 611 618 728 with no new failures. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com> Message-Id: <2e63b26e-df46-5baa-c7d6-f9a8dd3282c5@google.com> Signed-off-by: Christian Brauner <brauner@kernel.org>
132 lines
4.3 KiB
C
132 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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File: linux/xattr.h
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Extended attributes handling.
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Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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Copyright (c) 2001-2002 Silicon Graphics, Inc. All Rights Reserved.
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Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*/
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#ifndef _LINUX_XATTR_H
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#define _LINUX_XATTR_H
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#include <linux/slab.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/mm.h>
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#include <linux/user_namespace.h>
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#include <uapi/linux/xattr.h>
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struct inode;
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struct dentry;
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static inline bool is_posix_acl_xattr(const char *name)
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{
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return (strcmp(name, XATTR_NAME_POSIX_ACL_ACCESS) == 0) ||
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(strcmp(name, XATTR_NAME_POSIX_ACL_DEFAULT) == 0);
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}
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/*
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* struct xattr_handler: When @name is set, match attributes with exactly that
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* name. When @prefix is set instead, match attributes with that prefix and
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* with a non-empty suffix.
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*/
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struct xattr_handler {
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const char *name;
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const char *prefix;
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int flags; /* fs private flags */
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bool (*list)(struct dentry *dentry);
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int (*get)(const struct xattr_handler *, struct dentry *dentry,
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struct inode *inode, const char *name, void *buffer,
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size_t size);
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int (*set)(const struct xattr_handler *,
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struct mnt_idmap *idmap, struct dentry *dentry,
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struct inode *inode, const char *name, const void *buffer,
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size_t size, int flags);
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};
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/**
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* xattr_handler_can_list - check whether xattr can be listed
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* @handler: handler for this type of xattr
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* @dentry: dentry whose inode xattr to list
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*
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* Determine whether the xattr associated with @dentry can be listed given
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* @handler.
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*
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* Return: true if xattr can be listed, false if not.
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*/
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static inline bool xattr_handler_can_list(const struct xattr_handler *handler,
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struct dentry *dentry)
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{
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return handler && (!handler->list || handler->list(dentry));
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}
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const char *xattr_full_name(const struct xattr_handler *, const char *);
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struct xattr {
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const char *name;
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void *value;
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size_t value_len;
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};
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ssize_t __vfs_getxattr(struct dentry *, struct inode *, const char *, void *, size_t);
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ssize_t vfs_getxattr(struct mnt_idmap *, struct dentry *, const char *,
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void *, size_t);
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ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
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int __vfs_setxattr(struct mnt_idmap *, struct dentry *, struct inode *,
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const char *, const void *, size_t, int);
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int __vfs_setxattr_noperm(struct mnt_idmap *, struct dentry *,
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const char *, const void *, size_t, int);
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int __vfs_setxattr_locked(struct mnt_idmap *, struct dentry *,
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const char *, const void *, size_t, int,
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struct inode **);
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int vfs_setxattr(struct mnt_idmap *, struct dentry *, const char *,
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const void *, size_t, int);
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int __vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
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int __vfs_removexattr_locked(struct mnt_idmap *, struct dentry *,
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const char *, struct inode **);
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int vfs_removexattr(struct mnt_idmap *, struct dentry *, const char *);
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ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
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int vfs_getxattr_alloc(struct mnt_idmap *idmap,
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struct dentry *dentry, const char *name,
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char **xattr_value, size_t size, gfp_t flags);
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int xattr_supports_user_prefix(struct inode *inode);
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static inline const char *xattr_prefix(const struct xattr_handler *handler)
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{
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return handler->prefix ?: handler->name;
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}
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struct simple_xattrs {
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struct rb_root rb_root;
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rwlock_t lock;
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};
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struct simple_xattr {
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struct rb_node rb_node;
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char *name;
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size_t size;
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char value[];
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};
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void simple_xattrs_init(struct simple_xattrs *xattrs);
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void simple_xattrs_free(struct simple_xattrs *xattrs, size_t *freed_space);
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size_t simple_xattr_space(const char *name, size_t size);
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struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
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void simple_xattr_free(struct simple_xattr *xattr);
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int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
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void *buffer, size_t size);
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struct simple_xattr *simple_xattr_set(struct simple_xattrs *xattrs,
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const char *name, const void *value,
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size_t size, int flags);
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ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
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char *buffer, size_t size);
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void simple_xattr_add(struct simple_xattrs *xattrs,
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struct simple_xattr *new_xattr);
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int xattr_list_one(char **buffer, ssize_t *remaining_size, const char *name);
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#endif /* _LINUX_XATTR_H */
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