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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 :
30 : struct 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 :
40 : struct ext4_xattr_ibody_header {
41 : __le32 h_magic; /* magic number for identification */
42 : };
43 :
44 : struct 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 :
111 : struct 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 :
119 : struct 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 :
127 : struct ext4_xattr_ibody_find {
128 : struct ext4_xattr_search s;
129 : struct ext4_iloc iloc;
130 : };
131 :
132 : struct ext4_xattr_inode_array {
133 : unsigned int count; /* # of used items in the array */
134 : struct inode *inodes[];
135 : };
136 :
137 : extern const struct xattr_handler ext4_xattr_user_handler;
138 : extern const struct xattr_handler ext4_xattr_trusted_handler;
139 : extern const struct xattr_handler ext4_xattr_security_handler;
140 : extern 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 : */
153 0 : static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
154 : {
155 0 : down_write(&EXT4_I(inode)->xattr_sem);
156 0 : *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
157 0 : ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
158 0 : }
159 :
160 0 : static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
161 : {
162 0 : if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
163 : return 0;
164 0 : *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
165 0 : ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
166 0 : return 1;
167 : }
168 :
169 0 : static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
170 : {
171 0 : if (*save == 0)
172 0 : ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
173 0 : up_write(&EXT4_I(inode)->xattr_sem);
174 0 : }
175 :
176 : extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
177 :
178 : extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
179 : extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
180 : extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
181 : extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
182 : bool is_create, int *credits);
183 : extern 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 :
187 : extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
188 : struct ext4_xattr_inode_array **array,
189 : int extra_credits);
190 : extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
191 :
192 : extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
193 : struct ext4_inode *raw_inode, handle_t *handle);
194 : extern void ext4_evict_ea_inode(struct inode *inode);
195 :
196 : extern const struct xattr_handler *ext4_xattr_handlers[];
197 :
198 : extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
199 : struct ext4_xattr_ibody_find *is);
200 : extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
201 : const char *name,
202 : void *buffer, size_t buffer_size);
203 : extern 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 :
207 : extern struct mb_cache *ext4_xattr_create_cache(void);
208 : extern void ext4_xattr_destroy_cache(struct mb_cache *);
209 :
210 : #ifdef CONFIG_EXT4_FS_SECURITY
211 : extern int ext4_init_security(handle_t *handle, struct inode *inode,
212 : struct inode *dir, const struct qstr *qstr);
213 : #else
214 : static 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
222 : extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
223 : #else
224 : static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
225 : #endif
226 :
227 : extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);
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