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_block;  /* disk block attribute is stored on (n/i) */
  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 #define BHDR(bh) ((struct ext4_xattr_header *)((bh)->b_data))
  73 #define ENTRY(ptr) ((struct ext4_xattr_entry *)(ptr))
  74 #define BFIRST(bh) ENTRY(BHDR(bh)+1)
  75 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
  76
  77 #define EXT4_ZERO_XATTR_VALUE ((void *)-1)
  78
  79 struct ext4_xattr_info {
  80         int name_index;
  81         const char *name;
  82         const void *value;
  83         size_t value_len;
  84 };
  85
  86 struct ext4_xattr_search {
  87         struct ext4_xattr_entry *first;
  88         void *base;
  89         void *end;
  90         struct ext4_xattr_entry *here;
  91         int not_found;
  92 };
  93
  94 struct ext4_xattr_ibody_find {
  95         struct ext4_xattr_search s;
  96         struct ext4_iloc iloc;
  97 };
  98
  99 extern const struct xattr_handler ext4_xattr_user_handler;
 100 extern const struct xattr_handler ext4_xattr_trusted_handler;
 101 extern const struct xattr_handler ext4_xattr_security_handler;
 102
 103 #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
 104
 105 /*
 106  * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
 107  * The first is to signal that there the inline xattrs and data are
 108  * taking up so much space that we might as well not keep trying to
 109  * expand it.  The second is that xattr_sem is taken for writing, so
 110  * we shouldn't try to recurse into the inode expansion.  For this
 111  * second case, we need to make sure that we take save and restore the
 112  * NO_EXPAND state flag appropriately.
 113  */
 114 static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
 115 {
 116         down_write(&EXT4_I(inode)->xattr_sem);
 117         *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
 118         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 119 }
 120
 121 static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
 122 {
 123         if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
 124                 return 0;
 125         *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
 126         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 127         return 1;
 128 }
 129
 130 static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
 131 {
 132         if (*save == 0)
 133                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
 134         up_write(&EXT4_I(inode)->xattr_sem);
 135 }
 136
 137 extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
 138
 139 extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
 140 extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
 141 extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
 142
 143 extern void ext4_xattr_delete_inode(handle_t *, struct inode *);
 144
 145 extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 146                             struct ext4_inode *raw_inode, handle_t *handle);
 147
 148 extern const struct xattr_handler *ext4_xattr_handlers[];
 149
 150 extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 151                                  struct ext4_xattr_ibody_find *is);
 152 extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
 153                                 const char *name,
 154                                 void *buffer, size_t buffer_size);
 155 extern int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
 156                                        struct ext4_xattr_info *i,
 157                                        struct ext4_xattr_ibody_find *is);
 158
 159 extern struct mb_cache *ext4_xattr_create_cache(void);
 160 extern void ext4_xattr_destroy_cache(struct mb_cache *);
 161
 162 #ifdef CONFIG_EXT4_FS_SECURITY
 163 extern int ext4_init_security(handle_t *handle, struct inode *inode,
 164                               struct inode *dir, const struct qstr *qstr);
 165 #else
 166 static inline int ext4_init_security(handle_t *handle, struct inode *inode,
 167                                      struct inode *dir, const struct qstr *qstr)
 168 {
 169         return 0;
 170 }
 171 #endif