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+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);