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 */
ext4_write_lock_xattr(struct inode * inode,int * save)153 static 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
ext4_write_trylock_xattr(struct inode * inode,int * save)160 static 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
ext4_write_unlock_xattr(struct inode * inode,int * save)169 static 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
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
ext4_init_security(handle_t * handle,struct inode * inode,struct inode * dir,const struct qstr * qstr)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
ext4_xattr_inode_set_class(struct inode * ea_inode)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);
228