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[0];	/* 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[0];
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 
141 #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
142 
143 /*
144  * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
145  * The first is to signal that there the inline xattrs and data are
146  * taking up so much space that we might as well not keep trying to
147  * expand it.  The second is that xattr_sem is taken for writing, so
148  * we shouldn't try to recurse into the inode expansion.  For this
149  * second case, we need to make sure that we take save and restore the
150  * NO_EXPAND state flag appropriately.
151  */
ext4_write_lock_xattr(struct inode * inode,int * save)152 static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
153 {
154 	down_write(&EXT4_I(inode)->xattr_sem);
155 	*save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
156 	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
157 }
158 
ext4_write_trylock_xattr(struct inode * inode,int * save)159 static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
160 {
161 	if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
162 		return 0;
163 	*save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
164 	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
165 	return 1;
166 }
167 
ext4_write_unlock_xattr(struct inode * inode,int * save)168 static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
169 {
170 	if (*save == 0)
171 		ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
172 	up_write(&EXT4_I(inode)->xattr_sem);
173 }
174 
175 extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
176 
177 extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
178 extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
179 extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
180 extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
181 				  bool is_create, int *credits);
182 extern int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
183 				struct buffer_head *block_bh, size_t value_len,
184 				bool is_create);
185 
186 extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
187 				   struct ext4_xattr_inode_array **array,
188 				   int extra_credits);
189 extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
190 
191 extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
192 			    struct ext4_inode *raw_inode, handle_t *handle);
193 extern void ext4_evict_ea_inode(struct inode *inode);
194 
195 extern const struct xattr_handler *ext4_xattr_handlers[];
196 
197 extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
198 				 struct ext4_xattr_ibody_find *is);
199 extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
200 				const char *name,
201 				void *buffer, size_t buffer_size);
202 extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
203 				struct ext4_xattr_info *i,
204 				struct ext4_xattr_ibody_find *is);
205 
206 extern struct mb_cache *ext4_xattr_create_cache(void);
207 extern void ext4_xattr_destroy_cache(struct mb_cache *);
208 
209 #ifdef CONFIG_EXT4_FS_SECURITY
210 extern int ext4_init_security(handle_t *handle, struct inode *inode,
211 			      struct inode *dir, const struct qstr *qstr);
212 #else
ext4_init_security(handle_t * handle,struct inode * inode,struct inode * dir,const struct qstr * qstr)213 static inline int ext4_init_security(handle_t *handle, struct inode *inode,
214 				     struct inode *dir, const struct qstr *qstr)
215 {
216 	return 0;
217 }
218 #endif
219 
220 #ifdef CONFIG_LOCKDEP
221 extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
222 #else
ext4_xattr_inode_set_class(struct inode * ea_inode)223 static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
224 #endif
225 
226 extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);
227