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+blknum+xattrblock) */ 36 __u32 h_reserved[3]; /* zero right now */ 37 }; 38 39 struct ext4_xattr_ibody_header { 40 __le32 h_magic; /* magic number for identification */ 41 }; 42 43 struct 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 IFIRST(hdr) ((struct ext4_xattr_entry *)((hdr)+1)) 71 72 /* 73 * XATTR_SIZE_MAX is currently 64k, but for the purposes of checking 74 * for file system consistency errors, we use a somewhat bigger value. 75 * This allows XATTR_SIZE_MAX to grow in the future, but by using this 76 * instead of INT_MAX for certain consistency checks, we don't need to 77 * worry about arithmetic overflows. (Actually XATTR_SIZE_MAX is 78 * defined in include/uapi/linux/limits.h, so changing it is going 79 * not going to be trivial....) 80 */ 81 #define EXT4_XATTR_SIZE_MAX (1 << 24) 82 83 /* 84 * The minimum size of EA value when you start storing it in an external inode 85 * size of block - size of header - size of 1 entry - 4 null bytes 86 */ 87 #define EXT4_XATTR_MIN_LARGE_EA_SIZE(b) \ 88 ((b) - EXT4_XATTR_LEN(3) - sizeof(struct ext4_xattr_header) - 4) 89 90 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data)) 91 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr)) 92 #define BFIRST(bh) ENTRY(BHDR(bh)+1) 93 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) 94 95 #define EXT4_ZERO_XATTR_VALUE ((void *)-1) 96 97 /* 98 * If we want to add an xattr to the inode, we should make sure that 99 * i_extra_isize is not 0 and that the inode size is not less than 100 * EXT4_GOOD_OLD_INODE_SIZE + extra_isize + pad. 101 * EXT4_GOOD_OLD_INODE_SIZE extra_isize header entry pad data 102 * |--------------------------|------------|------|---------|---|-------| 103 */ 104 #define EXT4_INODE_HAS_XATTR_SPACE(inode) \ 105 ((EXT4_I(inode)->i_extra_isize != 0) && \ 106 (EXT4_GOOD_OLD_INODE_SIZE + EXT4_I(inode)->i_extra_isize + \ 107 sizeof(struct ext4_xattr_ibody_header) + EXT4_XATTR_PAD <= \ 108 EXT4_INODE_SIZE((inode)->i_sb))) 109 110 struct ext4_xattr_info { 111 const char *name; 112 const void *value; 113 size_t value_len; 114 int name_index; 115 int in_inode; 116 }; 117 118 struct ext4_xattr_search { 119 struct ext4_xattr_entry *first; 120 void *base; 121 void *end; 122 struct ext4_xattr_entry *here; 123 int not_found; 124 }; 125 126 struct ext4_xattr_ibody_find { 127 struct ext4_xattr_search s; 128 struct ext4_iloc iloc; 129 }; 130 131 struct ext4_xattr_inode_array { 132 unsigned int count; 133 struct inode *inodes[] __counted_by(count); 134 }; 135 136 extern const struct xattr_handler ext4_xattr_user_handler; 137 extern const struct xattr_handler ext4_xattr_trusted_handler; 138 extern const struct xattr_handler ext4_xattr_security_handler; 139 extern const struct xattr_handler ext4_xattr_hurd_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 */ 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 } 158 159 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 } 167 168 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 * const 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 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 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