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 ITAIL(inode, raw_inode) \
72 ((void *)(raw_inode) + \
73 EXT4_SB((inode)->i_sb)->s_inode_size)
74 #define IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1))
75
76 /*
77 * XATTR_SIZE_MAX is currently 64k, but for the purposes of checking
78 * for file system consistency errors, we use a somewhat bigger value.
79 * This allows XATTR_SIZE_MAX to grow in the future, but by using this
80 * instead of INT_MAX for certain consistency checks, we don't need to
81 * worry about arithmetic overflows. (Actually XATTR_SIZE_MAX is
82 * defined in include/uapi/linux/limits.h, so changing it is going
83 * not going to be trivial....)
84 */
85 #define EXT4_XATTR_SIZE_MAX (1 << 24)
86
87 /*
88 * The minimum size of EA value when you start storing it in an external inode
89 * size of block - size of header - size of 1 entry - 4 null bytes
90 */
91 #define EXT4_XATTR_MIN_LARGE_EA_SIZE(b) \
92 ((b) - EXT4_XATTR_LEN(3) - sizeof(struct ext4_xattr_header) - 4)
93
94 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
95 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
96 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
97 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
98
99 #define EXT4_ZERO_XATTR_VALUE ((void *)-1)
100
101 /*
102 * If we want to add an xattr to the inode, we should make sure that
103 * i_extra_isize is not 0 and that the inode size is not less than
104 * EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad.
105 * EXT4_GOOD_OLD_INODE_SIZE extra_isize header entry pad data
106 * |--------------------------|------------|------|---------|---|-------|
107 */
108 #define EXT4_INODE_HAS_XATTR_SPACE(inode) \
109 ((EXT4_I(inode)->i_extra_isize != 0) && \
110 (EXT4_GOOD_OLD_INODE_SIZE + EXT4_I(inode)->i_extra_isize + \
111 sizeof(struct ext4_xattr_ibody_header) + EXT4_XATTR_PAD <= \
112 EXT4_INODE_SIZE((inode)->i_sb)))
113
114 struct ext4_xattr_info {
115 const char *name;
116 const void *value;
117 size_t value_len;
118 int name_index;
119 int in_inode;
120 };
121
122 struct ext4_xattr_search {
123 struct ext4_xattr_entry *first;
124 void *base;
125 void *end;
126 struct ext4_xattr_entry *here;
127 int not_found;
128 };
129
130 struct ext4_xattr_ibody_find {
131 struct ext4_xattr_search s;
132 struct ext4_iloc iloc;
133 };
134
135 struct ext4_xattr_inode_array {
136 unsigned int count; /* # of used items in the array */
137 struct inode *inodes[];
138 };
139
140 extern const struct xattr_handler ext4_xattr_user_handler;
141 extern const struct xattr_handler ext4_xattr_trusted_handler;
142 extern const struct xattr_handler ext4_xattr_security_handler;
143 extern const struct xattr_handler ext4_xattr_hurd_handler;
144
145 #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
146
147 /*
148 * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
149 * The first is to signal that there the inline xattrs and data are
150 * taking up so much space that we might as well not keep trying to
151 * expand it. The second is that xattr_sem is taken for writing, so
152 * we shouldn't try to recurse into the inode expansion. For this
153 * second case, we need to make sure that we take save and restore the
154 * NO_EXPAND state flag appropriately.
155 */
ext4_write_lock_xattr(struct inode * inode,int * save)156 static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
157 {
158 down_write(&EXT4_I(inode)->xattr_sem);
159 *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
160 ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
161 }
162
ext4_write_trylock_xattr(struct inode * inode,int * save)163 static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
164 {
165 if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
166 return 0;
167 *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
168 ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
169 return 1;
170 }
171
ext4_write_unlock_xattr(struct inode * inode,int * save)172 static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
173 {
174 if (*save == 0)
175 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
176 up_write(&EXT4_I(inode)->xattr_sem);
177 }
178
179 extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
180
181 extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
182 extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
183 extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
184 extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
185 bool is_create, int *credits);
186 extern int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
187 struct buffer_head *block_bh, size_t value_len,
188 bool is_create);
189
190 extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
191 struct ext4_xattr_inode_array **array,
192 int extra_credits);
193 extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
194
195 extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
196 struct ext4_inode *raw_inode, handle_t *handle);
197 extern void ext4_evict_ea_inode(struct inode *inode);
198
199 extern const struct xattr_handler *ext4_xattr_handlers[];
200
201 extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
202 struct ext4_xattr_ibody_find *is);
203 extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
204 const char *name,
205 void *buffer, size_t buffer_size);
206 extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
207 struct ext4_xattr_info *i,
208 struct ext4_xattr_ibody_find *is);
209
210 extern struct mb_cache *ext4_xattr_create_cache(void);
211 extern void ext4_xattr_destroy_cache(struct mb_cache *);
212
213 extern int
214 __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
215 void *end, const char *function, unsigned int line);
216
217 #define xattr_check_inode(inode, header, end) \
218 __xattr_check_inode((inode), (header), (end), __func__, __LINE__)
219
220 #ifdef CONFIG_EXT4_FS_SECURITY
221 extern int ext4_init_security(handle_t *handle, struct inode *inode,
222 struct inode *dir, const struct qstr *qstr);
223 #else
ext4_init_security(handle_t * handle,struct inode * inode,struct inode * dir,const struct qstr * qstr)224 static inline int ext4_init_security(handle_t *handle, struct inode *inode,
225 struct inode *dir, const struct qstr *qstr)
226 {
227 return 0;
228 }
229 #endif
230
231 #ifdef CONFIG_LOCKDEP
232 extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
233 #else
ext4_xattr_inode_set_class(struct inode * ea_inode)234 static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
235 #endif
236
237 extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);
238