fs/ext4/xattr.h

   1 /*
   2   File: fs/ext4/xattr.h
   3
   4   On-disk format of extended attributes for the ext4 filesystem.
   5
   6   (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
   7 */
   8
   9 #include <linux/xattr.h>
  10
  11 /* Magic value in attribute blocks */
  12 #define EXT4_XATTR_MAGIC                0xEA020000
  13
  14 /* Maximum number of references to one attribute block */
  15 #define EXT4_XATTR_REFCOUNT_MAX         1024
  16
  17 /* Name indexes */
  18 #define EXT4_XATTR_INDEX_USER                   1
  19 #define EXT4_XATTR_INDEX_POSIX_ACL_ACCESS       2
  20 #define EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT      3
  21 #define EXT4_XATTR_INDEX_TRUSTED                4
  22 #define EXT4_XATTR_INDEX_LUSTRE                 5
  23 #define EXT4_XATTR_INDEX_SECURITY               6
  24 #define EXT4_XATTR_INDEX_SYSTEM                 7
  25 #define EXT4_XATTR_INDEX_RICHACL                8
  26 #define EXT4_XATTR_INDEX_ENCRYPTION             9
  27 #define EXT4_XATTR_INDEX_HURD                   10 /* Reserved for Hurd */
  28
  29 struct ext4_xattr_header {
  30         __le32  h_magic;        /* magic number for identification */
  31         __le32  h_refcount;     /* reference count */
  32         __le32  h_blocks;       /* number of disk blocks used */
  33         __le32  h_hash;         /* hash value of all attributes */
  34         __le32  h_checksum;     /* crc32c(uuid+id+xattrblock) */
  35                                 /* id = inum if refcount=1, blknum otherwise */
  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[0];      /* 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  * Link EA inode back to parent one using i_mtime field.
  74  * Extra integer type conversion added to ignore higher
  75  * bits in i_mtime.tv_sec which might be set by ext4_get()
  76  */
  77 #define EXT4_XATTR_INODE_SET_PARENT(inode, inum)      \
  78 do {                                                  \
  79       (inode)->i_mtime.tv_sec = inum;                 \
  80 } while(0)
  81
  82 #define EXT4_XATTR_INODE_GET_PARENT(inode)            \
  83 ((__u32)(inode)->i_mtime.tv_sec)
  84
  85 /*
  86  * The minimum size of EA value when you start storing it in an external inode
  87  * size of block - size of header - size of 1 entry - 4 null bytes
  88 */
  89 #define EXT4_XATTR_MIN_LARGE_EA_SIZE(b)                                 \
  90         ((b) - EXT4_XATTR_LEN(3) - sizeof(struct ext4_xattr_header) - 4)
  91
  92 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
  93 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
  94 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  95 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  96
  97 #define EXT4_ZERO_XATTR_VALUE ((void *)-1)
  98
  99 struct ext4_xattr_info {
 100         const char *name;
 101         const void *value;
 102         size_t value_len;
 103         int name_index;
 104         int in_inode;
 105 };
 106
 107 struct ext4_xattr_search {
 108         struct ext4_xattr_entry *first;
 109         void *base;
 110         void *end;
 111         struct ext4_xattr_entry *here;
 112         int not_found;
 113 };
 114
 115 struct ext4_xattr_ibody_find {
 116         struct ext4_xattr_search s;
 117         struct ext4_iloc iloc;
 118 };
 119
 120 struct ext4_xattr_inode_array {
 121         unsigned int count;             /* # of used items in the array */
 122         struct inode *inodes[0];
 123 };
 124
 125 extern const struct xattr_handler ext4_xattr_user_handler;
 126 extern const struct xattr_handler ext4_xattr_trusted_handler;
 127 extern const struct xattr_handler ext4_xattr_security_handler;
 128
 129 #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
 130
 131 /*
 132  * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
 133  * The first is to signal that there the inline xattrs and data are
 134  * taking up so much space that we might as well not keep trying to
 135  * expand it.  The second is that xattr_sem is taken for writing, so
 136  * we shouldn't try to recurse into the inode expansion.  For this
 137  * second case, we need to make sure that we take save and restore the
 138  * NO_EXPAND state flag appropriately.
 139  */
 140 static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
 141 {
 142         down_write(&EXT4_I(inode)->xattr_sem);
 143         *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
 144         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 145 }
 146
 147 static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
 148 {
 149         if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
 150                 return 0;
 151         *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
 152         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 153         return 1;
 154 }
 155
 156 static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
 157 {
 158         if (*save == 0)
 159                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
 160         up_write(&EXT4_I(inode)->xattr_sem);
 161 }
 162
 163 extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
 164
 165 extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
 166 extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
 167 extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
 168 extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len);
 169
 170 extern int ext4_xattr_inode_unlink(struct inode *inode, unsigned long ea_ino);
 171 extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
 172                                    struct ext4_xattr_inode_array **array);
 173 extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
 174
 175 extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 176                             struct ext4_inode *raw_inode, handle_t *handle);
 177
 178 extern const struct xattr_handler *ext4_xattr_handlers[];
 179
 180 extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 181                                  struct ext4_xattr_ibody_find *is);
 182 extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
 183                                 const char *name,
 184                                 void *buffer, size_t buffer_size);
 185 extern int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
 186                                        struct ext4_xattr_info *i,
 187                                        struct ext4_xattr_ibody_find *is);
 188
 189 extern struct mb_cache *ext4_xattr_create_cache(void);
 190 extern void ext4_xattr_destroy_cache(struct mb_cache *);
 191
 192 #ifdef CONFIG_EXT4_FS_SECURITY
 193 extern int ext4_init_security(handle_t *handle, struct inode *inode,
 194                               struct inode *dir, const struct qstr *qstr);
 195 #else
 196 static inline int ext4_init_security(handle_t *handle, struct inode *inode,
 197                                      struct inode *dir, const struct qstr *qstr)
 198 {
 199         return 0;
 200 }
 201 #endif
 202
 203 #ifdef CONFIG_LOCKDEP
 204 extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
 205 #else
 206 static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
 207 #endif