linux/fs/ext4/xattr.c

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/ext4/xattr.c
 *
 * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
 *
 * Fix by Harrison Xing <[email protected]>.
 * Ext4 code with a lot of help from Eric Jarman <[email protected]>.
 * Extended attributes for symlinks and special files added per
 *  suggestion of Luka Renko <[email protected]>.
 * xattr consolidation Copyright (c) 2004 James Morris <[email protected]>,
 *  Red Hat Inc.
 * ea-in-inode support by Alex Tomas <[email protected]> aka bzzz
 *  and Andreas Gruenbacher <[email protected]>.
 */

/*
 * Extended attributes are stored directly in inodes (on file systems with
 * inodes bigger than 128 bytes) and on additional disk blocks. The i_file_acl
 * field contains the block number if an inode uses an additional block. All
 * attributes must fit in the inode and one additional block. Blocks that
 * contain the identical set of attributes may be shared among several inodes.
 * Identical blocks are detected by keeping a cache of blocks that have
 * recently been accessed.
 *
 * The attributes in inodes and on blocks have a different header; the entries
 * are stored in the same format:
 *
 *   +------------------+
 *   | header           |
 *   | entry 1          | |
 *   | entry 2          | | growing downwards
 *   | entry 3          | v
 *   | four null bytes  |
 *   | . . .            |
 *   | value 1          | ^
 *   | value 3          | | growing upwards
 *   | value 2          | |
 *   +------------------+
 *
 * The header is followed by multiple entry descriptors. In disk blocks, the
 * entry descriptors are kept sorted. In inodes, they are unsorted. The
 * attribute values are aligned to the end of the block in no specific order.
 *
 * Locking strategy
 * ----------------
 * EXT4_I(inode)->i_file_acl is protected by EXT4_I(inode)->xattr_sem.
 * EA blocks are only changed if they are exclusive to an inode, so
 * holding xattr_sem also means that nothing but the EA block's reference
 * count can change. Multiple writers to the same block are synchronized
 * by the buffer lock.
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/mbcache.h>
#include <linux/quotaops.h>
#include <linux/iversion.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "xattr.h"
#include "acl.h"

#ifdef EXT4_XATTR_DEBUG
#define ea_idebug …
#define ea_bdebug …
#else
#define ea_idebug(inode, fmt, ...) …
#define ea_bdebug(bh, fmt, ...) …
#endif

static void ext4_xattr_block_cache_insert(struct mb_cache *,
					  struct buffer_head *);
static struct buffer_head *
ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *,
			    struct mb_cache_entry **);
static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
				    size_t value_count);
static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value,
				    size_t value_count);
static void ext4_xattr_rehash(struct ext4_xattr_header *);

static const struct xattr_handler * const ext4_xattr_handler_map[] = …;

const struct xattr_handler * const ext4_xattr_handlers[] = …;

#define EA_BLOCK_CACHE(inode) …

#define EA_INODE_CACHE(inode) …

static int
ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
			struct inode *inode);

#ifdef CONFIG_LOCKDEP
void ext4_xattr_inode_set_class(struct inode *ea_inode)
{ … }
#endif

static __le32 ext4_xattr_block_csum(struct inode *inode,
				    sector_t block_nr,
				    struct ext4_xattr_header *hdr)
{ … }

static int ext4_xattr_block_csum_verify(struct inode *inode,
					struct buffer_head *bh)
{ … }

static void ext4_xattr_block_csum_set(struct inode *inode,
				      struct buffer_head *bh)
{ … }

static inline const char *ext4_xattr_prefix(int name_index,
					    struct dentry *dentry)
{ … }

static int
check_xattrs(struct inode *inode, struct buffer_head *bh,
	     struct ext4_xattr_entry *entry, void *end, void *value_start,
	     const char *function, unsigned int line)
{ … }

static inline int
__ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
			 const char *function, unsigned int line)
{ … }

#define ext4_xattr_check_block(inode, bh) …


static inline int
__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
			 void *end, const char *function, unsigned int line)
{ … }

#define xattr_check_inode(inode, header, end) …

static int
xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry,
		 void *end, int name_index, const char *name, int sorted)
{ … }

static u32
ext4_xattr_inode_hash(struct ext4_sb_info *sbi, const void *buffer, size_t size)
{ … }

static u64 ext4_xattr_inode_get_ref(struct inode *ea_inode)
{ … }

static void ext4_xattr_inode_set_ref(struct inode *ea_inode, u64 ref_count)
{ … }

static u32 ext4_xattr_inode_get_hash(struct inode *ea_inode)
{ … }

static void ext4_xattr_inode_set_hash(struct inode *ea_inode, u32 hash)
{ … }

/*
 * Read the EA value from an inode.
 */
static int ext4_xattr_inode_read(struct inode *ea_inode, void *buf, size_t size)
{ … }

#define EXT4_XATTR_INODE_GET_PARENT(inode) …

static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
				 u32 ea_inode_hash, struct inode **ea_inode)
{ … }

/* Remove entry from mbcache when EA inode is getting evicted */
void ext4_evict_ea_inode(struct inode *inode)
{ … }

static int
ext4_xattr_inode_verify_hashes(struct inode *ea_inode,
			       struct ext4_xattr_entry *entry, void *buffer,
			       size_t size)
{ … }

/*
 * Read xattr value from the EA inode.
 */
static int
ext4_xattr_inode_get(struct inode *inode, struct ext4_xattr_entry *entry,
		     void *buffer, size_t size)
{ … }

static int
ext4_xattr_block_get(struct inode *inode, int name_index, const char *name,
		     void *buffer, size_t buffer_size)
{ … }

int
ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name,
		     void *buffer, size_t buffer_size)
{ … }

/*
 * ext4_xattr_get()
 *
 * Copy an extended attribute into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
int
ext4_xattr_get(struct inode *inode, int name_index, const char *name,
	       void *buffer, size_t buffer_size)
{ … }

static int
ext4_xattr_list_entries(struct dentry *dentry, struct ext4_xattr_entry *entry,
			char *buffer, size_t buffer_size)
{ … }

static int
ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{ … }

static int
ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{ … }

/*
 * Inode operation listxattr()
 *
 * d_inode(dentry)->i_rwsem: don't care
 *
 * Copy a list of attribute names into the buffer
 * provided, or compute the buffer size required.
 * Buffer is NULL to compute the size of the buffer required.
 *
 * Returns a negative error number on failure, or the number of bytes
 * used / required on success.
 */
ssize_t
ext4_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{ … }

/*
 * If the EXT4_FEATURE_COMPAT_EXT_ATTR feature of this file system is
 * not set, set it.
 */
static void ext4_xattr_update_super_block(handle_t *handle,
					  struct super_block *sb)
{ … }

int ext4_get_inode_usage(struct inode *inode, qsize_t *usage)
{ … }

static inline size_t round_up_cluster(struct inode *inode, size_t length)
{ … }

static int ext4_xattr_inode_alloc_quota(struct inode *inode, size_t len)
{ … }

static void ext4_xattr_inode_free_quota(struct inode *parent,
					struct inode *ea_inode,
					size_t len)
{ … }

int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
			     struct buffer_head *block_bh, size_t value_len,
			     bool is_create)
{ … }

static int ext4_xattr_inode_update_ref(handle_t *handle, struct inode *ea_inode,
				       int ref_change)
{ … }

static int ext4_xattr_inode_inc_ref(handle_t *handle, struct inode *ea_inode)
{ … }

static int ext4_xattr_inode_dec_ref(handle_t *handle, struct inode *ea_inode)
{ … }

static int ext4_xattr_inode_inc_ref_all(handle_t *handle, struct inode *parent,
					struct ext4_xattr_entry *first)
{ … }

static int ext4_xattr_restart_fn(handle_t *handle, struct inode *inode,
			struct buffer_head *bh, bool block_csum, bool dirty)
{ … }

static void
ext4_xattr_inode_dec_ref_all(handle_t *handle, struct inode *parent,
			     struct buffer_head *bh,
			     struct ext4_xattr_entry *first, bool block_csum,
			     struct ext4_xattr_inode_array **ea_inode_array,
			     int extra_credits, bool skip_quota)
{ … }

/*
 * Release the xattr block BH: If the reference count is > 1, decrement it;
 * otherwise free the block.
 */
static void
ext4_xattr_release_block(handle_t *handle, struct inode *inode,
			 struct buffer_head *bh,
			 struct ext4_xattr_inode_array **ea_inode_array,
			 int extra_credits)
{ … }

/*
 * Find the available free space for EAs. This also returns the total number of
 * bytes used by EA entries.
 */
static size_t ext4_xattr_free_space(struct ext4_xattr_entry *last,
				    size_t *min_offs, void *base, int *total)
{ … }

/*
 * Write the value of the EA in an inode.
 */
static int ext4_xattr_inode_write(handle_t *handle, struct inode *ea_inode,
				  const void *buf, int bufsize)
{ … }

/*
 * Create an inode to store the value of a large EA.
 */
static struct inode *ext4_xattr_inode_create(handle_t *handle,
					     struct inode *inode, u32 hash)
{ … }

static struct inode *
ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
			    size_t value_len, u32 hash)
{ … }

/*
 * Add value of the EA in an inode.
 */
static struct inode *ext4_xattr_inode_lookup_create(handle_t *handle,
		struct inode *inode, const void *value, size_t value_len)
{ … }

/*
 * Reserve min(block_size/8, 1024) bytes for xattr entries/names if ea_inode
 * feature is enabled.
 */
#define EXT4_XATTR_BLOCK_RESERVE(inode) …

static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
				struct ext4_xattr_search *s,
				handle_t *handle, struct inode *inode,
				struct inode *new_ea_inode,
				bool is_block)
{ … }

struct ext4_xattr_block_find { … };

static int
ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i,
		      struct ext4_xattr_block_find *bs)
{ … }

static int
ext4_xattr_block_set(handle_t *handle, struct inode *inode,
		     struct ext4_xattr_info *i,
		     struct ext4_xattr_block_find *bs)
{ … }

int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i,
			  struct ext4_xattr_ibody_find *is)
{ … }

int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
				struct ext4_xattr_info *i,
				struct ext4_xattr_ibody_find *is)
{ … }

static int ext4_xattr_value_same(struct ext4_xattr_search *s,
				 struct ext4_xattr_info *i)
{ … }

static struct buffer_head *ext4_xattr_get_block(struct inode *inode)
{ … }

/*
 * ext4_xattr_set_handle()
 *
 * Create, replace or remove an extended attribute for this inode.  Value
 * is NULL to remove an existing extended attribute, and non-NULL to
 * either replace an existing extended attribute, or create a new extended
 * attribute. The flags XATTR_REPLACE and XATTR_CREATE
 * specify that an extended attribute must exist and must not exist
 * previous to the call, respectively.
 *
 * Returns 0, or a negative error number on failure.
 */
int
ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
		      const char *name, const void *value, size_t value_len,
		      int flags)
{ … }

int ext4_xattr_set_credits(struct inode *inode, size_t value_len,
			   bool is_create, int *credits)
{ … }

/*
 * ext4_xattr_set()
 *
 * Like ext4_xattr_set_handle, but start from an inode. This extended
 * attribute modification is a filesystem transaction by itself.
 *
 * Returns 0, or a negative error number on failure.
 */
int
ext4_xattr_set(struct inode *inode, int name_index, const char *name,
	       const void *value, size_t value_len, int flags)
{ … }

/*
 * Shift the EA entries in the inode to create space for the increased
 * i_extra_isize.
 */
static void ext4_xattr_shift_entries(struct ext4_xattr_entry *entry,
				     int value_offs_shift, void *to,
				     void *from, size_t n)
{ … }

/*
 * Move xattr pointed to by 'entry' from inode into external xattr block
 */
static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode,
				    struct ext4_inode *raw_inode,
				    struct ext4_xattr_entry *entry)
{ … }

static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
				       struct ext4_inode *raw_inode,
				       int isize_diff, size_t ifree,
				       size_t bfree, int *total_ino)
{ … }

/*
 * Expand an inode by new_extra_isize bytes when EAs are present.
 * Returns 0 on success or negative error number on failure.
 */
int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
			       struct ext4_inode *raw_inode, handle_t *handle)
{ … }

#define EIA_INCR …
#define EIA_MASK …

/* Add the large xattr @inode into @ea_inode_array for deferred iput().
 * If @ea_inode_array is new or full it will be grown and the old
 * contents copied over.
 */
static int
ext4_expand_inode_array(struct ext4_xattr_inode_array **ea_inode_array,
			struct inode *inode)
{ … }

/*
 * ext4_xattr_delete_inode()
 *
 * Free extended attribute resources associated with this inode. Traverse
 * all entries and decrement reference on any xattr inodes associated with this
 * inode. This is called immediately before an inode is freed. We have exclusive
 * access to the inode. If an orphan inode is deleted it will also release its
 * references on xattr block and xattr inodes.
 */
int ext4_xattr_delete_inode(handle_t *handle, struct inode *inode,
			    struct ext4_xattr_inode_array **ea_inode_array,
			    int extra_credits)
{ … }

void ext4_xattr_inode_array_free(struct ext4_xattr_inode_array *ea_inode_array)
{ … }

/*
 * ext4_xattr_block_cache_insert()
 *
 * Create a new entry in the extended attribute block cache, and insert
 * it unless such an entry is already in the cache.
 *
 * Returns 0, or a negative error number on failure.
 */
static void
ext4_xattr_block_cache_insert(struct mb_cache *ea_block_cache,
			      struct buffer_head *bh)
{ … }

/*
 * ext4_xattr_cmp()
 *
 * Compare two extended attribute blocks for equality.
 *
 * Returns 0 if the blocks are equal, 1 if they differ, and
 * a negative error number on errors.
 */
static int
ext4_xattr_cmp(struct ext4_xattr_header *header1,
	       struct ext4_xattr_header *header2)
{ … }

/*
 * ext4_xattr_block_cache_find()
 *
 * Find an identical extended attribute block.
 *
 * Returns a pointer to the block found, or NULL if such a block was not
 * found, or an error pointer if an error occurred while reading ea block.
 */
static struct buffer_head *
ext4_xattr_block_cache_find(struct inode *inode,
			    struct ext4_xattr_header *header,
			    struct mb_cache_entry **pce)
{ … }

#define NAME_HASH_SHIFT …
#define VALUE_HASH_SHIFT …

/*
 * ext4_xattr_hash_entry()
 *
 * Compute the hash of an extended attribute.
 */
static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value,
				    size_t value_count)
{ … }

/*
 * ext4_xattr_hash_entry_signed()
 *
 * Compute the hash of an extended attribute incorrectly.
 */
static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, size_t value_count)
{ … }

#undef NAME_HASH_SHIFT
#undef VALUE_HASH_SHIFT

#define BLOCK_HASH_SHIFT …

/*
 * ext4_xattr_rehash()
 *
 * Re-compute the extended attribute hash value after an entry has changed.
 */
static void ext4_xattr_rehash(struct ext4_xattr_header *header)
{ … }

#undef BLOCK_HASH_SHIFT

#define HASH_BUCKET_BITS …

struct mb_cache *
ext4_xattr_create_cache(void)
{ … }

void ext4_xattr_destroy_cache(struct mb_cache *cache)
{ … }