fs/ext4/xattr.h

   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 struct ext4_xattr_info {
  99         const char *name;
 100         const void *value;
 101         size_t value_len;
 102         int name_index;
 103         int in_inode;
 104 };
 105
 106 struct ext4_xattr_search {
 107         struct ext4_xattr_entry *first;
 108         void *base;
 109         void *end;
 110         struct ext4_xattr_entry *here;
 111         int not_found;
 112 };
 113
 114 struct ext4_xattr_ibody_find {
 115         struct ext4_xattr_search s;
 116         struct ext4_iloc iloc;
 117 };
 118
 119 struct ext4_xattr_inode_array {
 120         unsigned int count;             /* # of used items in the array */
 121         struct inode *inodes[0];
 122 };
 123
 124 extern const struct xattr_handler ext4_xattr_user_handler;
 125 extern const struct xattr_handler ext4_xattr_trusted_handler;
 126 extern const struct xattr_handler ext4_xattr_security_handler;
 127
 128 #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c"
 129
 130 /*
 131  * The EXT4_STATE_NO_EXPAND is overloaded and used for two purposes.
 132  * The first is to signal that there the inline xattrs and data are
 133  * taking up so much space that we might as well not keep trying to
 134  * expand it.  The second is that xattr_sem is taken for writing, so
 135  * we shouldn't try to recurse into the inode expansion.  For this
 136  * second case, we need to make sure that we take save and restore the
 137  * NO_EXPAND state flag appropriately.
 138  */
 139 static inline void ext4_write_lock_xattr(struct inode *inode, int *save)
 140 {
 141         down_write(&EXT4_I(inode)->xattr_sem);
 142         *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
 143         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 144 }
 145
 146 static inline int ext4_write_trylock_xattr(struct inode *inode, int *save)
 147 {
 148         if (down_write_trylock(&EXT4_I(inode)->xattr_sem) == 0)
 149                 return 0;
 150         *save = ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND);
 151         ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 152         return 1;
 153 }
 154
 155 static inline void ext4_write_unlock_xattr(struct inode *inode, int *save)
 156 {
 157         if (*save == 0)
 158                 ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
 159         up_write(&EXT4_I(inode)->xattr_sem);
 160 }
 161
 162 extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
 163
 164 extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
 165 extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
 166 extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
 167 extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
 168                                   bool is_create, int *credits);
 169 extern int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
 170                                 struct buffer_head *block_bh, size_t value_len,
 171                                 bool is_create);
 172
 173 extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
 174                                    struct ext4_xattr_inode_array **array,
 175                                    int extra_credits);
 176 extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
 177
 178 extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 179                             struct ext4_inode *raw_inode, handle_t *handle);
 180
 181 extern const struct xattr_handler *ext4_xattr_handlers[];
 182
 183 extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 184                                  struct ext4_xattr_ibody_find *is);
 185 extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
 186                                 const char *name,
 187                                 void *buffer, size_t buffer_size);
 188 extern int ext4_xattr_ibody_inline_set(handle_t *handle, struct inode *inode,
 189                                        struct ext4_xattr_info *i,
 190                                        struct ext4_xattr_ibody_find *is);
 191
 192 extern struct mb_cache *ext4_xattr_create_cache(void);
 193 extern void ext4_xattr_destroy_cache(struct mb_cache *);
 194
 195 #ifdef CONFIG_EXT4_FS_SECURITY
 196 extern int ext4_init_security(handle_t *handle, struct inode *inode,
 197                               struct inode *dir, const struct qstr *qstr);
 198 #else
 199 static inline int ext4_init_security(handle_t *handle, struct inode *inode,
 200                                      struct inode *dir, const struct qstr *qstr)
 201 {
 202         return 0;
 203 }
 204 #endif
 205
 206 #ifdef CONFIG_LOCKDEP
 207 extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
 208 #else
 209 static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
 210 #endif
 211
 212 extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);