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