LXR linux/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
  30struct 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
  40struct ext4_xattr_ibody_header {
  41        __le32  h_magic;        /* magic number for identification */
  42};
  43
  44struct 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
  98struct 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
 106struct 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
 114struct ext4_xattr_ibody_find {
 115        struct ext4_xattr_search s;
 116        struct ext4_iloc iloc;
 117};
 118
 119struct ext4_xattr_inode_array {
 120        unsigned int count;             /* # of used items in the array */
 121        struct inode *inodes[];
 122};
 123
 124extern const struct xattr_handler ext4_xattr_user_handler;
 125extern const struct xattr_handler ext4_xattr_trusted_handler;
 126extern const struct xattr_handler ext4_xattr_security_handler;
 127extern const struct xattr_handler ext4_xattr_hurd_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 */
 140static 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
 147static 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
 156static 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
 163extern ssize_t ext4_listxattr(struct dentry *, char *, size_t);
 164
 165extern int ext4_xattr_get(struct inode *, int, const char *, void *, size_t);
 166extern int ext4_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
 167extern int ext4_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
 168extern int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
 169                                  bool is_create, int *credits);
 170extern int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
 171                                struct buffer_head *block_bh, size_t value_len,
 172                                bool is_create);
 173
 174extern int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
 175                                   struct ext4_xattr_inode_array **array,
 176                                   int extra_credits);
 177extern void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *array);
 178
 179extern int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 180                            struct ext4_inode *raw_inode, handle_t *handle);
 181
 182extern const struct xattr_handler *ext4_xattr_handlers[];
 183
 184extern int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
 185                                 struct ext4_xattr_ibody_find *is);
 186extern int ext4_xattr_ibody_get(struct inode *inode, int name_index,
 187                                const char *name,
 188                                void *buffer, size_t buffer_size);
 189extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
 190                                struct ext4_xattr_info *i,
 191                                struct ext4_xattr_ibody_find *is);
 192
 193extern struct mb_cache *ext4_xattr_create_cache(void);
 194extern void ext4_xattr_destroy_cache(struct mb_cache *);
 195
 196#ifdef CONFIG_EXT4_FS_SECURITY
 197extern int ext4_init_security(handle_t *handle, struct inode *inode,
 198                              struct inode *dir, const struct qstr *qstr);
 199#else
 200static inline int ext4_init_security(handle_t *handle, struct inode *inode,
 201                                     struct inode *dir, const struct qstr *qstr)
 202{
 203        return 0;
 204}
 205#endif
 206
 207#ifdef CONFIG_LOCKDEP
 208extern void ext4_xattr_inode_set_class(struct inode *ea_inode);
 209#else
 210static inline void ext4_xattr_inode_set_class(struct inode *ea_inode) { }
 211#endif
 212
 213extern int ext4_get_inode_usage(struct inode *inode, qsize_t *usage);
 214