xattr.h

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3  File: fs/ext4/xattr.h
  4
  5  On-disk format of extended attributes for the ext4 filesystem.
  6
  7  (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
  8*/
  9
 10#include <linux/xattr.h>
 11
 12/* Magic value in attribute blocks */
 13#define EXT4_XATTR_MAGIC		0xEA020000
 14
 15/* Maximum number of references to one attribute block */
 16#define EXT4_XATTR_REFCOUNT_MAX		1024
 17
 18/* Name indexes */
 19#define EXT4_XATTR_INDEX_USER			1
 20#define EXT4_XATTR_INDEX_POSIX_ACL_ACCESS	2
 21#define EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT	3
 22#define EXT4_XATTR_INDEX_TRUSTED		4
 23#define	EXT4_XATTR_INDEX_LUSTRE			5
 24#define EXT4_XATTR_INDEX_SECURITY	        6
 25#define EXT4_XATTR_INDEX_SYSTEM			7
 26#define EXT4_XATTR_INDEX_RICHACL		8
 27#define EXT4_XATTR_INDEX_ENCRYPTION		9
 28#define EXT4_XATTR_INDEX_HURD			10 /* Reserved for Hurd */
 29
 30struct ext4_xattr_header {
 31	__le32	h_magic;	/* magic number for identification */
 32	__le32	h_refcount;	/* reference count */
 33	__le32	h_blocks;	/* number of disk blocks used */
 34	__le32	h_hash;		/* hash value of all attributes */
 35	__le32	h_checksum;	/* crc32c(uuid+blknum+xattrblock) */
 36	__u32	h_reserved[3];	/* zero right now */
 37};
 38
 39struct ext4_xattr_ibody_header {
 40	__le32	h_magic;	/* magic number for identification */
 41};
 42
 43struct ext4_xattr_entry {
 44	__u8	e_name_len;	/* length of name */
 45	__u8	e_name_index;	/* attribute name index */
 46	__le16	e_value_offs;	/* offset in disk block of value */
 47	__le32	e_value_inum;	/* inode in which the value is stored */
 48	__le32	e_value_size;	/* size of attribute value */
 49	__le32	e_hash;		/* hash value of name and value */
 50	char	e_name[];	/* attribute name */
 51};
 52
 53#define EXT4_XATTR_PAD_BITS		2
 54#define EXT4_XATTR_PAD		(1<<EXT4_XATTR_PAD_BITS)
 55#define EXT4_XATTR_ROUND		(EXT4_XATTR_PAD-1)
 56#define EXT4_XATTR_LEN(name_len) \
 57	(((name_len) + EXT4_XATTR_ROUND + \
 58	sizeof(struct ext4_xattr_entry)) & ~EXT4_XATTR_ROUND)
 59#define EXT4_XATTR_NEXT(entry) \
 60	((struct ext4_xattr_entry *)( \
 61	 (char *)(entry) + EXT4_XATTR_LEN((entry)->e_name_len)))
 62#define EXT4_XATTR_SIZE(size) \
 63	(((size) + EXT4_XATTR_ROUND) & ~EXT4_XATTR_ROUND)
 64
 65#define IHDR(inode, raw_inode) \
 66	((struct ext4_xattr_ibody_header *) \
 67		((void *)raw_inode + \
 68		EXT4_GOOD_OLD_INODE_SIZE + \
 69		EXT4_I(inode)->i_extra_isize))
 70#define ITAIL(inode, raw_inode) \
 71	((void *)(raw_inode) + \
 72	 EXT4_SB((inode)->i_sb)->s_inode_size)
 73#define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
 74
 75/*
 76 * XATTR_SIZE_MAX is currently 64k, but for the purposes of checking
 77 * for file system consistency errors, we use a somewhat bigger value.
 78 * This allows XATTR_SIZE_MAX to grow in the future, but by using this
 79 * instead of INT_MAX for certain consistency checks, we don't need to
 80 * worry about arithmetic overflows.  (Actually XATTR_SIZE_MAX is
 81 * defined in include/uapi/linux/limits.h, so changing it is going
 82 * not going to be trivial....)
 83 */
 84#define EXT4_XATTR_SIZE_MAX (1 << 24)
 85
 86/*
 87 * The minimum size of EA value when you start storing it in an external inode
 88 * size of block - size of header - size of 1 entry - 4 null bytes
 89 */
 90#define EXT4_XATTR_MIN_LARGE_EA_SIZE(b)					\
 91	((b) - EXT4_XATTR_LEN(3) - sizeof(struct ext4_xattr_header) - 4)
 92
 93#define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
 94#define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
 95#define BFIRST(bh) ENTRY(BHDR(bh)+1)
 96#define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
 97
 98#define EXT4_ZERO_XATTR_VALUE ((void *)-1)
 99
100/*
101 * If we want to add an xattr to the inode, we should make sure that
102 * i_extra_isize is not 0 and that the inode size is not less than
103 * EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad.
104 *   EXT4_GOOD_OLD_INODE_SIZE   extra_isize header   entry   pad  data
105 * |--------------------------|------------|------|---------|---|-------|
106 */
107#define EXT4_INODE_HAS_XATTR_SPACE(inode)				\
108	((EXT4_I(inode)->i_extra_isize != 0) &&				\
109	 (EXT4_GOOD_OLD_INODE_SIZE + EXT4_I(inode)->i_extra_isize +	\
110	  sizeof(struct ext4_xattr_ibody_header) + EXT4_XATTR_PAD <=	\
111	  EXT4_INODE_SIZE((inode)->i_sb)))
112
113struct ext4_xattr_info {
114	const char *name;
115	const void *value;
116	size_t value_len;
117	int name_index;
118	int in_inode;
119};
120
121struct ext4_xattr_search {
122	struct ext4_xattr_entry *first;
123	void *base;
124	void *end;
125	struct ext4_xattr_entry *here;
126	int not_found;
127};
128
129struct ext4_xattr_ibody_find {
130	struct ext4_xattr_search s;
131	struct ext4_iloc iloc;
132};
133
134struct ext4_xattr_inode_array {
135	unsigned int count;
136	struct inode *inodes[] __counted_by(count);
137};
138
139extern const struct xattr_handler ext4_xattr_user_handler;
140extern const struct xattr_handler ext4_xattr_trusted_handler;
141extern const struct xattr_handler ext4_xattr_security_handler;
142extern const struct xattr_handler ext4_xattr_hurd_handler;
143
144#define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
145
146/*
147 * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
148 * The first is to signal that there the inline xattrs and data are
149 * taking up so much space that we might as well not keep trying to
150 * expand it.  The second is that xattr_sem is taken for writing, so
151 * we shouldn't try to recurse into the inode expansion.  For this
152 * second case, we need to make sure that we take save and restore the
153 * NO_EXPAND state flag appropriately.
154 */
155static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
156{
157	down_write(&EXT4_I(inode)->xattr_sem);
158	*save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
159	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
160}
161
162static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
163{
164	if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
165		return 0;
166	*save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
167	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
168	return 1;
169}
170
171static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
172{
173	if (*save == 0)
174		ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
175	up_write(&EXT4_I(inode)->xattr_sem);
176}
177
178extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
179
180extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
181extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
182extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
183extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
184				  bool is_create, int *credits);
185extern int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
186				struct buffer_head *block_bh, size_t value_len,
187				bool is_create);
188
189extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
190				   struct ext4_xattr_inode_array **array,
191				   int extra_credits);
192extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
193
194extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
195			    struct ext4_inode *raw_inode, handle_t *handle);
196extern void ext4_evict_ea_inode(struct inode *inode);
197
198extern const struct xattr_handler * const ext4_xattr_handlers[];
199
200extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
201				 struct ext4_xattr_ibody_find *is);
202extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
203				const char *name,
204				void *buffer, size_t buffer_size);
205extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
206				struct ext4_xattr_info *i,
207				struct ext4_xattr_ibody_find *is);
208
209extern struct mb_cache *ext4_xattr_create_cache(void);
210extern void ext4_xattr_destroy_cache(struct mb_cache *);
211
212extern int
213__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
214		    void *end, const char *function, unsigned int line);
215
216#define xattr_check_inode(inode, header, end) \
217	__xattr_check_inode((inode), (header), (end), __func__, __LINE__)
218
219#ifdef CONFIG_EXT4_FS_SECURITY
220extern int ext4_init_security(handle_t *handle, struct inode *inode,
221			      struct inode *dir, const struct qstr *qstr);
222#else
223static inline int ext4_init_security(handle_t *handle, struct inode *inode,
224				     struct inode *dir, const struct qstr *qstr)
225{
226	return 0;
227}
228#endif
229
230#ifdef CONFIG_LOCKDEP
231extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
232#else
233static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
234#endif
235
236extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);