mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-15 15:04:27 +08:00
0c47383ba3
User extended attributes are useful as metadata storage for kernfs consumers like cgroups. Especially in the case of cgroups, it is useful to have a central metadata store that multiple processes/services can use to coordinate actions. A concrete example is for userspace out of memory killers. We want to let delegated cgroup subtree owners (running as non-root) to be able to say "please avoid killing this cgroup". This is especially important for desktop linux as delegated subtrees owners are less likely to run as root. This patch introduces a new flag, KERNFS_ROOT_SUPPORT_USER_XATTR, that lets kernfs consumers enable user xattr support. An initial limit of 128 entries or 128KB -- whichever is hit first -- is placed per cgroup because xattrs come from kernel memory and we don't want to let unprivileged users accidentally eat up too much kernel memory. Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Acked-by: Chris Down <chris@chrisdown.name> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tejun Heo <tj@kernel.org>
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* fs/kernfs/kernfs-internal.h - kernfs internal header file
|
|
*
|
|
* Copyright (c) 2001-3 Patrick Mochel
|
|
* Copyright (c) 2007 SUSE Linux Products GmbH
|
|
* Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de>
|
|
*/
|
|
|
|
#ifndef __KERNFS_INTERNAL_H
|
|
#define __KERNFS_INTERNAL_H
|
|
|
|
#include <linux/lockdep.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/mutex.h>
|
|
#include <linux/xattr.h>
|
|
|
|
#include <linux/kernfs.h>
|
|
#include <linux/fs_context.h>
|
|
|
|
struct kernfs_iattrs {
|
|
kuid_t ia_uid;
|
|
kgid_t ia_gid;
|
|
struct timespec64 ia_atime;
|
|
struct timespec64 ia_mtime;
|
|
struct timespec64 ia_ctime;
|
|
|
|
struct simple_xattrs xattrs;
|
|
atomic_t nr_user_xattrs;
|
|
atomic_t user_xattr_size;
|
|
};
|
|
|
|
/* +1 to avoid triggering overflow warning when negating it */
|
|
#define KN_DEACTIVATED_BIAS (INT_MIN + 1)
|
|
|
|
/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
|
|
|
|
/**
|
|
* kernfs_root - find out the kernfs_root a kernfs_node belongs to
|
|
* @kn: kernfs_node of interest
|
|
*
|
|
* Return the kernfs_root @kn belongs to.
|
|
*/
|
|
static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn)
|
|
{
|
|
/* if parent exists, it's always a dir; otherwise, @sd is a dir */
|
|
if (kn->parent)
|
|
kn = kn->parent;
|
|
return kn->dir.root;
|
|
}
|
|
|
|
/*
|
|
* mount.c
|
|
*/
|
|
struct kernfs_super_info {
|
|
struct super_block *sb;
|
|
|
|
/*
|
|
* The root associated with this super_block. Each super_block is
|
|
* identified by the root and ns it's associated with.
|
|
*/
|
|
struct kernfs_root *root;
|
|
|
|
/*
|
|
* Each sb is associated with one namespace tag, currently the
|
|
* network namespace of the task which mounted this kernfs
|
|
* instance. If multiple tags become necessary, make the following
|
|
* an array and compare kernfs_node tag against every entry.
|
|
*/
|
|
const void *ns;
|
|
|
|
/* anchored at kernfs_root->supers, protected by kernfs_mutex */
|
|
struct list_head node;
|
|
};
|
|
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
|
|
|
|
static inline struct kernfs_node *kernfs_dentry_node(struct dentry *dentry)
|
|
{
|
|
if (d_really_is_negative(dentry))
|
|
return NULL;
|
|
return d_inode(dentry)->i_private;
|
|
}
|
|
|
|
extern const struct super_operations kernfs_sops;
|
|
extern struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
|
|
|
|
/*
|
|
* inode.c
|
|
*/
|
|
extern const struct xattr_handler *kernfs_xattr_handlers[];
|
|
void kernfs_evict_inode(struct inode *inode);
|
|
int kernfs_iop_permission(struct inode *inode, int mask);
|
|
int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr);
|
|
int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
|
|
u32 request_mask, unsigned int query_flags);
|
|
ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size);
|
|
int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
|
|
|
|
/*
|
|
* dir.c
|
|
*/
|
|
extern struct mutex kernfs_mutex;
|
|
extern const struct dentry_operations kernfs_dops;
|
|
extern const struct file_operations kernfs_dir_fops;
|
|
extern const struct inode_operations kernfs_dir_iops;
|
|
|
|
struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);
|
|
void kernfs_put_active(struct kernfs_node *kn);
|
|
int kernfs_add_one(struct kernfs_node *kn);
|
|
struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
|
|
const char *name, umode_t mode,
|
|
kuid_t uid, kgid_t gid,
|
|
unsigned flags);
|
|
|
|
/*
|
|
* file.c
|
|
*/
|
|
extern const struct file_operations kernfs_file_fops;
|
|
|
|
void kernfs_drain_open_files(struct kernfs_node *kn);
|
|
|
|
/*
|
|
* symlink.c
|
|
*/
|
|
extern const struct inode_operations kernfs_symlink_iops;
|
|
|
|
#endif /* __KERNFS_INTERNAL_H */
|