| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* |
| * kernfs.h - pseudo filesystem decoupled from vfs locking |
| */ |
| |
| #ifndef __LINUX_KERNFS_H |
| #define __LINUX_KERNFS_H |
| |
| #include <linux/kernel.h> |
| #include <linux/err.h> |
| #include <linux/list.h> |
| #include <linux/mutex.h> |
| #include <linux/idr.h> |
| #include <linux/lockdep.h> |
| #include <linux/rbtree.h> |
| #include <linux/atomic.h> |
| #include <linux/uidgid.h> |
| #include <linux/wait.h> |
| |
| struct file; |
| struct dentry; |
| struct iattr; |
| struct seq_file; |
| struct vm_area_struct; |
| struct super_block; |
| struct file_system_type; |
| struct poll_table_struct; |
| struct fs_context; |
| |
| struct kernfs_fs_context; |
| struct kernfs_open_node; |
| struct kernfs_iattrs; |
| |
| enum kernfs_node_type { |
| KERNFS_DIR = 0x0001, |
| KERNFS_FILE = 0x0002, |
| KERNFS_LINK = 0x0004, |
| }; |
| |
| #define KERNFS_TYPE_MASK 0x000f |
| #define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK |
| #define KERNFS_MAX_USER_XATTRS 128 |
| #define KERNFS_USER_XATTR_SIZE_LIMIT (128 << 10) |
| |
| enum kernfs_node_flag { |
| KERNFS_ACTIVATED = 0x0010, |
| KERNFS_NS = 0x0020, |
| KERNFS_HAS_SEQ_SHOW = 0x0040, |
| KERNFS_HAS_MMAP = 0x0080, |
| KERNFS_LOCKDEP = 0x0100, |
| KERNFS_SUICIDAL = 0x0400, |
| KERNFS_SUICIDED = 0x0800, |
| KERNFS_EMPTY_DIR = 0x1000, |
| KERNFS_HAS_RELEASE = 0x2000, |
| }; |
| |
| /* @flags for kernfs_create_root() */ |
| enum kernfs_root_flag { |
| /* |
| * kernfs_nodes are created in the deactivated state and invisible. |
| * They require explicit kernfs_activate() to become visible. This |
| * can be used to make related nodes become visible atomically |
| * after all nodes are created successfully. |
| */ |
| KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001, |
| |
| /* |
| * For regular files, if the opener has CAP_DAC_OVERRIDE, open(2) |
| * succeeds regardless of the RW permissions. sysfs had an extra |
| * layer of enforcement where open(2) fails with -EACCES regardless |
| * of CAP_DAC_OVERRIDE if the permission doesn't have the |
| * respective read or write access at all (none of S_IRUGO or |
| * S_IWUGO) or the respective operation isn't implemented. The |
| * following flag enables that behavior. |
| */ |
| KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK = 0x0002, |
| |
| /* |
| * The filesystem supports exportfs operation, so userspace can use |
| * fhandle to access nodes of the fs. |
| */ |
| KERNFS_ROOT_SUPPORT_EXPORTOP = 0x0004, |
| |
| /* |
| * Support user xattrs to be written to nodes rooted at this root. |
| */ |
| KERNFS_ROOT_SUPPORT_USER_XATTR = 0x0008, |
| }; |
| |
| /* type-specific structures for kernfs_node union members */ |
| struct kernfs_elem_dir { |
| unsigned long subdirs; |
| /* children rbtree starts here and goes through kn->rb */ |
| struct rb_root children; |
| |
| /* |
| * The kernfs hierarchy this directory belongs to. This fits |
| * better directly in kernfs_node but is here to save space. |
| */ |
| struct kernfs_root *root; |
| }; |
| |
| struct kernfs_elem_symlink { |
| struct kernfs_node *target_kn; |
| }; |
| |
| struct kernfs_elem_attr { |
| const struct kernfs_ops *ops; |
| struct kernfs_open_node *open; |
| loff_t size; |
| struct kernfs_node *notify_next; /* for kernfs_notify() */ |
| }; |
| |
| /* |
| * kernfs_node - the building block of kernfs hierarchy. Each and every |
| * kernfs node is represented by single kernfs_node. Most fields are |
| * private to kernfs and shouldn't be accessed directly by kernfs users. |
| * |
| * As long as count reference is held, the kernfs_node itself is |
| * accessible. Dereferencing elem or any other outer entity requires |
| * active reference. |
| */ |
| struct kernfs_node { |
| atomic_t count; |
| atomic_t active; |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| struct lockdep_map dep_map; |
| #endif |
| /* |
| * Use kernfs_get_parent() and kernfs_name/path() instead of |
| * accessing the following two fields directly. If the node is |
| * never moved to a different parent, it is safe to access the |
| * parent directly. |
| */ |
| struct kernfs_node *parent; |
| const char *name; |
| |
| struct rb_node rb; |
| |
| const void *ns; /* namespace tag */ |
| unsigned int hash; /* ns + name hash */ |
| union { |
| struct kernfs_elem_dir dir; |
| struct kernfs_elem_symlink symlink; |
| struct kernfs_elem_attr attr; |
| }; |
| |
| void *priv; |
| |
| /* |
| * 64bit unique ID. On 64bit ino setups, id is the ino. On 32bit, |
| * the low 32bits are ino and upper generation. |
| */ |
| u64 id; |
| |
| unsigned short flags; |
| umode_t mode; |
| struct kernfs_iattrs *iattr; |
| }; |
| |
| /* |
| * kernfs_syscall_ops may be specified on kernfs_create_root() to support |
| * syscalls. These optional callbacks are invoked on the matching syscalls |
| * and can perform any kernfs operations which don't necessarily have to be |
| * the exact operation requested. An active reference is held for each |
| * kernfs_node parameter. |
| */ |
| struct kernfs_syscall_ops { |
| int (*show_options)(struct seq_file *sf, struct kernfs_root *root); |
| |
| int (*mkdir)(struct kernfs_node *parent, const char *name, |
| umode_t mode); |
| int (*rmdir)(struct kernfs_node *kn); |
| int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent, |
| const char *new_name); |
| int (*show_path)(struct seq_file *sf, struct kernfs_node *kn, |
| struct kernfs_root *root); |
| }; |
| |
| struct kernfs_root { |
| /* published fields */ |
| struct kernfs_node *kn; |
| unsigned int flags; /* KERNFS_ROOT_* flags */ |
| |
| /* private fields, do not use outside kernfs proper */ |
| struct idr ino_idr; |
| u32 last_id_lowbits; |
| u32 id_highbits; |
| struct kernfs_syscall_ops *syscall_ops; |
| |
| /* list of kernfs_super_info of this root, protected by kernfs_mutex */ |
| struct list_head supers; |
| |
| wait_queue_head_t deactivate_waitq; |
| }; |
| |
| struct kernfs_open_file { |
| /* published fields */ |
| struct kernfs_node *kn; |
| struct file *file; |
| struct seq_file *seq_file; |
| void *priv; |
| |
| /* private fields, do not use outside kernfs proper */ |
| struct mutex mutex; |
| struct mutex prealloc_mutex; |
| int event; |
| struct list_head list; |
| char *prealloc_buf; |
| |
| size_t atomic_write_len; |
| bool mmapped:1; |
| bool released:1; |
| const struct vm_operations_struct *vm_ops; |
| }; |
| |
| struct kernfs_ops { |
| /* |
| * Optional open/release methods. Both are called with |
| * @of->seq_file populated. |
| */ |
| int (*open)(struct kernfs_open_file *of); |
| void (*release)(struct kernfs_open_file *of); |
| |
| /* |
| * Read is handled by either seq_file or raw_read(). |
| * |
| * If seq_show() is present, seq_file path is active. Other seq |
| * operations are optional and if not implemented, the behavior is |
| * equivalent to single_open(). @sf->private points to the |
| * associated kernfs_open_file. |
| * |
| * read() is bounced through kernel buffer and a read larger than |
| * PAGE_SIZE results in partial operation of PAGE_SIZE. |
| */ |
| int (*seq_show)(struct seq_file *sf, void *v); |
| |
| void *(*seq_start)(struct seq_file *sf, loff_t *ppos); |
| void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); |
| void (*seq_stop)(struct seq_file *sf, void *v); |
| |
| ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes, |
| loff_t off); |
| |
| /* |
| * write() is bounced through kernel buffer. If atomic_write_len |
| * is not set, a write larger than PAGE_SIZE results in partial |
| * operations of PAGE_SIZE chunks. If atomic_write_len is set, |
| * writes upto the specified size are executed atomically but |
| * larger ones are rejected with -E2BIG. |
| */ |
| size_t atomic_write_len; |
| /* |
| * "prealloc" causes a buffer to be allocated at open for |
| * all read/write requests. As ->seq_show uses seq_read() |
| * which does its own allocation, it is incompatible with |
| * ->prealloc. Provide ->read and ->write with ->prealloc. |
| */ |
| bool prealloc; |
| ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes, |
| loff_t off); |
| |
| __poll_t (*poll)(struct kernfs_open_file *of, |
| struct poll_table_struct *pt); |
| |
| int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma); |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| struct lock_class_key lockdep_key; |
| #endif |
| }; |
| |
| /* |
| * The kernfs superblock creation/mount parameter context. |
| */ |
| struct kernfs_fs_context { |
| struct kernfs_root *root; /* Root of the hierarchy being mounted */ |
| void *ns_tag; /* Namespace tag of the mount (or NULL) */ |
| unsigned long magic; /* File system specific magic number */ |
| |
| /* The following are set/used by kernfs_mount() */ |
| bool new_sb_created; /* Set to T if we allocated a new sb */ |
| }; |
| |
| #ifdef CONFIG_KERNFS |
| |
| static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn) |
| { |
| return kn->flags & KERNFS_TYPE_MASK; |
| } |
| |
| static inline ino_t kernfs_id_ino(u64 id) |
| { |
| /* id is ino if ino_t is 64bit; otherwise, low 32bits */ |
| if (sizeof(ino_t) >= sizeof(u64)) |
| return id; |
| else |
| return (u32)id; |
| } |
| |
| static inline u32 kernfs_id_gen(u64 id) |
| { |
| /* gen is fixed at 1 if ino_t is 64bit; otherwise, high 32bits */ |
| if (sizeof(ino_t) >= sizeof(u64)) |
| return 1; |
| else |
| return id >> 32; |
| } |
| |
| static inline ino_t kernfs_ino(struct kernfs_node *kn) |
| { |
| return kernfs_id_ino(kn->id); |
| } |
| |
| static inline ino_t kernfs_gen(struct kernfs_node *kn) |
| { |
| return kernfs_id_gen(kn->id); |
| } |
| |
| /** |
| * kernfs_enable_ns - enable namespace under a directory |
| * @kn: directory of interest, should be empty |
| * |
| * This is to be called right after @kn is created to enable namespace |
| * under it. All children of @kn must have non-NULL namespace tags and |
| * only the ones which match the super_block's tag will be visible. |
| */ |
| static inline void kernfs_enable_ns(struct kernfs_node *kn) |
| { |
| WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR); |
| WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children)); |
| kn->flags |= KERNFS_NS; |
| } |
| |
| /** |
| * kernfs_ns_enabled - test whether namespace is enabled |
| * @kn: the node to test |
| * |
| * Test whether namespace filtering is enabled for the children of @ns. |
| */ |
| static inline bool kernfs_ns_enabled(struct kernfs_node *kn) |
| { |
| return kn->flags & KERNFS_NS; |
| } |
| |
| int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen); |
| int kernfs_path_from_node(struct kernfs_node *root_kn, struct kernfs_node *kn, |
| char *buf, size_t buflen); |
| void pr_cont_kernfs_name(struct kernfs_node *kn); |
| void pr_cont_kernfs_path(struct kernfs_node *kn); |
| struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn); |
| struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, |
| const char *name, const void *ns); |
| struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent, |
| const char *path, const void *ns); |
| void kernfs_get(struct kernfs_node *kn); |
| void kernfs_put(struct kernfs_node *kn); |
| |
| struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry); |
| struct kernfs_root *kernfs_root_from_sb(struct super_block *sb); |
| struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn); |
| |
| struct dentry *kernfs_node_dentry(struct kernfs_node *kn, |
| struct super_block *sb); |
| struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops, |
| unsigned int flags, void *priv); |
| void kernfs_destroy_root(struct kernfs_root *root); |
| |
| struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, |
| const char *name, umode_t mode, |
| kuid_t uid, kgid_t gid, |
| void *priv, const void *ns); |
| struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent, |
| const char *name); |
| struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, |
| const char *name, umode_t mode, |
| kuid_t uid, kgid_t gid, |
| loff_t size, |
| const struct kernfs_ops *ops, |
| void *priv, const void *ns, |
| struct lock_class_key *key); |
| struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, |
| const char *name, |
| struct kernfs_node *target); |
| void kernfs_activate(struct kernfs_node *kn); |
| void kernfs_remove(struct kernfs_node *kn); |
| void kernfs_break_active_protection(struct kernfs_node *kn); |
| void kernfs_unbreak_active_protection(struct kernfs_node *kn); |
| bool kernfs_remove_self(struct kernfs_node *kn); |
| int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, |
| const void *ns); |
| int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, |
| const char *new_name, const void *new_ns); |
| int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr); |
| __poll_t kernfs_generic_poll(struct kernfs_open_file *of, |
| struct poll_table_struct *pt); |
| void kernfs_notify(struct kernfs_node *kn); |
| |
| int kernfs_xattr_get(struct kernfs_node *kn, const char *name, |
| void *value, size_t size); |
| int kernfs_xattr_set(struct kernfs_node *kn, const char *name, |
| const void *value, size_t size, int flags); |
| |
| const void *kernfs_super_ns(struct super_block *sb); |
| int kernfs_get_tree(struct fs_context *fc); |
| void kernfs_free_fs_context(struct fs_context *fc); |
| void kernfs_kill_sb(struct super_block *sb); |
| |
| void kernfs_init(void); |
| |
| struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, |
| u64 id); |
| #else /* CONFIG_KERNFS */ |
| |
| static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn) |
| { return 0; } /* whatever */ |
| |
| static inline void kernfs_enable_ns(struct kernfs_node *kn) { } |
| |
| static inline bool kernfs_ns_enabled(struct kernfs_node *kn) |
| { return false; } |
| |
| static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) |
| { return -ENOSYS; } |
| |
| static inline int kernfs_path_from_node(struct kernfs_node *root_kn, |
| struct kernfs_node *kn, |
| char *buf, size_t buflen) |
| { return -ENOSYS; } |
| |
| static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { } |
| static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { } |
| |
| static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) |
| { return NULL; } |
| |
| static inline struct kernfs_node * |
| kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name, |
| const void *ns) |
| { return NULL; } |
| static inline struct kernfs_node * |
| kernfs_walk_and_get_ns(struct kernfs_node *parent, const char *path, |
| const void *ns) |
| { return NULL; } |
| |
| static inline void kernfs_get(struct kernfs_node *kn) { } |
| static inline void kernfs_put(struct kernfs_node *kn) { } |
| |
| static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) |
| { return NULL; } |
| |
| static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb) |
| { return NULL; } |
| |
| static inline struct inode * |
| kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn) |
| { return NULL; } |
| |
| static inline struct kernfs_root * |
| kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags, |
| void *priv) |
| { return ERR_PTR(-ENOSYS); } |
| |
| static inline void kernfs_destroy_root(struct kernfs_root *root) { } |
| |
| static inline struct kernfs_node * |
| kernfs_create_dir_ns(struct kernfs_node *parent, const char *name, |
| umode_t mode, kuid_t uid, kgid_t gid, |
| void *priv, const void *ns) |
| { return ERR_PTR(-ENOSYS); } |
| |
| static inline struct kernfs_node * |
| __kernfs_create_file(struct kernfs_node *parent, const char *name, |
| umode_t mode, kuid_t uid, kgid_t gid, |
| loff_t size, const struct kernfs_ops *ops, |
| void *priv, const void *ns, struct lock_class_key *key) |
| { return ERR_PTR(-ENOSYS); } |
| |
| static inline struct kernfs_node * |
| kernfs_create_link(struct kernfs_node *parent, const char *name, |
| struct kernfs_node *target) |
| { return ERR_PTR(-ENOSYS); } |
| |
| static inline void kernfs_activate(struct kernfs_node *kn) { } |
| |
| static inline void kernfs_remove(struct kernfs_node *kn) { } |
| |
| static inline bool kernfs_remove_self(struct kernfs_node *kn) |
| { return false; } |
| |
| static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn, |
| const char *name, const void *ns) |
| { return -ENOSYS; } |
| |
| static inline int kernfs_rename_ns(struct kernfs_node *kn, |
| struct kernfs_node *new_parent, |
| const char *new_name, const void *new_ns) |
| { return -ENOSYS; } |
| |
| static inline int kernfs_setattr(struct kernfs_node *kn, |
| const struct iattr *iattr) |
| { return -ENOSYS; } |
| |
| static inline void kernfs_notify(struct kernfs_node *kn) { } |
| |
| static inline int kernfs_xattr_get(struct kernfs_node *kn, const char *name, |
| void *value, size_t size) |
| { return -ENOSYS; } |
| |
| static inline int kernfs_xattr_set(struct kernfs_node *kn, const char *name, |
| const void *value, size_t size, int flags) |
| { return -ENOSYS; } |
| |
| static inline const void *kernfs_super_ns(struct super_block *sb) |
| { return NULL; } |
| |
| static inline int kernfs_get_tree(struct fs_context *fc) |
| { return -ENOSYS; } |
| |
| static inline void kernfs_free_fs_context(struct fs_context *fc) { } |
| |
| static inline void kernfs_kill_sb(struct super_block *sb) { } |
| |
| static inline void kernfs_init(void) { } |
| |
| #endif /* CONFIG_KERNFS */ |
| |
| /** |
| * kernfs_path - build full path of a given node |
| * @kn: kernfs_node of interest |
| * @buf: buffer to copy @kn's name into |
| * @buflen: size of @buf |
| * |
| * If @kn is NULL result will be "(null)". |
| * |
| * Returns the length of the full path. If the full length is equal to or |
| * greater than @buflen, @buf contains the truncated path with the trailing |
| * '\0'. On error, -errno is returned. |
| */ |
| static inline int kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen) |
| { |
| return kernfs_path_from_node(kn, NULL, buf, buflen); |
| } |
| |
| static inline struct kernfs_node * |
| kernfs_find_and_get(struct kernfs_node *kn, const char *name) |
| { |
| return kernfs_find_and_get_ns(kn, name, NULL); |
| } |
| |
| static inline struct kernfs_node * |
| kernfs_walk_and_get(struct kernfs_node *kn, const char *path) |
| { |
| return kernfs_walk_and_get_ns(kn, path, NULL); |
| } |
| |
| static inline struct kernfs_node * |
| kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode, |
| void *priv) |
| { |
| return kernfs_create_dir_ns(parent, name, mode, |
| GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
| priv, NULL); |
| } |
| |
| static inline struct kernfs_node * |
| kernfs_create_file_ns(struct kernfs_node *parent, const char *name, |
| umode_t mode, kuid_t uid, kgid_t gid, |
| loff_t size, const struct kernfs_ops *ops, |
| void *priv, const void *ns) |
| { |
| struct lock_class_key *key = NULL; |
| |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| key = (struct lock_class_key *)&ops->lockdep_key; |
| #endif |
| return __kernfs_create_file(parent, name, mode, uid, gid, |
| size, ops, priv, ns, key); |
| } |
| |
| static inline struct kernfs_node * |
| kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode, |
| loff_t size, const struct kernfs_ops *ops, void *priv) |
| { |
| return kernfs_create_file_ns(parent, name, mode, |
| GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
| size, ops, priv, NULL); |
| } |
| |
| static inline int kernfs_remove_by_name(struct kernfs_node *parent, |
| const char *name) |
| { |
| return kernfs_remove_by_name_ns(parent, name, NULL); |
| } |
| |
| static inline int kernfs_rename(struct kernfs_node *kn, |
| struct kernfs_node *new_parent, |
| const char *new_name) |
| { |
| return kernfs_rename_ns(kn, new_parent, new_name, NULL); |
| } |
| |
| #endif /* __LINUX_KERNFS_H */ |