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(sem: &EXT4_I(inode)->xattr_sem);
158 *save = ext4_test_inode_state(inode, bit: EXT4_STATE_NO_EXPAND);
159 ext4_set_inode_state(inode, bit: EXT4_STATE_NO_EXPAND);
160}
161
162static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
163{
164 if (down_write_trylock(sem: &EXT4_I(inode)->xattr_sem) == 0)
165 return 0;
166 *save = ext4_test_inode_state(inode, bit: EXT4_STATE_NO_EXPAND);
167 ext4_set_inode_state(inode, bit: 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, bit: EXT4_STATE_NO_EXPAND);
175 up_write(sem: &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);
237

source code of linux/fs/ext4/xattr.h