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 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 } 159 160 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 } 168 169 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 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); 228