ref: dd3f008d8931f870814d139c4b61852cc4d449cb
dir: /src/ext4_xattr.c/
/*
* Copyright (c) 2015 Grzegorz Kostka (kostka.grzegorz@gmail.com)
* Copyright (c) 2015 Kaho Ng (ngkaho1234@gmail.com)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup lwext4
* @{
*/
/**
* @file ext4_xattr.c
* @brief Extended Attribute manipulation.
*/
#include <ext4_config.h>
#include <ext4_debug.h>
#include <ext4_errno.h>
#include <ext4_misc.h>
#include <ext4_types.h>
#include <ext4_balloc.h>
#include <ext4_block_group.h>
#include <ext4_blockdev.h>
#include <ext4_crc32.h>
#include <ext4_fs.h>
#include <ext4_inode.h>
#include <ext4_super.h>
#include <ext4_trans.h>
#include <ext4_xattr.h>
#include <stdlib.h>
#include <string.h>
/**
* @file ext4_xattr.c
* @brief Extended Attribute Manipulation
*/
#define NAME_HASH_SHIFT 5
#define VALUE_HASH_SHIFT 16
static inline void ext4_xattr_compute_hash(struct ext4_xattr_header *header,
struct ext4_xattr_entry *entry)
{
uint32_t hash = 0;
char *name = EXT4_XATTR_NAME(entry);
int n;
for (n = 0; n < entry->e_name_len; n++) {
hash = (hash << NAME_HASH_SHIFT) ^
(hash >> (8 * sizeof(hash) - NAME_HASH_SHIFT)) ^ *name++;
}
if (entry->e_value_block == 0 && entry->e_value_size != 0) {
uint32_t *value =
(uint32_t *)((char *)header + to_le16(entry->e_value_offs));
for (n = (to_le32(entry->e_value_size) + EXT4_XATTR_ROUND) >>
EXT4_XATTR_PAD_BITS;
n; n--) {
hash = (hash << VALUE_HASH_SHIFT) ^
(hash >> (8 * sizeof(hash) - VALUE_HASH_SHIFT)) ^
to_le32(*value++);
}
}
entry->e_hash = to_le32(hash);
}
#define BLOCK_HASH_SHIFT 16
/*
* 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,
struct ext4_xattr_entry *entry)
{
struct ext4_xattr_entry *here;
uint32_t hash = 0;
ext4_xattr_compute_hash(header, entry);
here = EXT4_XATTR_ENTRY(header + 1);
while (!EXT4_XATTR_IS_LAST_ENTRY(here)) {
if (!here->e_hash) {
/* Block is not shared if an entry's hash value == 0 */
hash = 0;
break;
}
hash = (hash << BLOCK_HASH_SHIFT) ^
(hash >> (8 * sizeof(hash) - BLOCK_HASH_SHIFT)) ^
to_le32(here->e_hash);
here = EXT4_XATTR_NEXT(here);
}
header->h_hash = to_le32(hash);
}
#if CONFIG_META_CSUM_ENABLE
static uint32_t ext4_xattr_block_checksum(struct ext4_inode_ref *inode_ref,
ext4_fsblk_t blocknr,
struct ext4_xattr_header *header)
{
uint32_t checksum = 0;
uint64_t le64_blocknr = blocknr;
struct ext4_sblock *sb = &inode_ref->fs->sb;
if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
uint32_t orig_checksum;
/* Preparation: temporarily set bg checksum to 0 */
orig_checksum = header->h_checksum;
header->h_checksum = 0;
/* First calculate crc32 checksum against fs uuid */
checksum =
ext4_crc32c(EXT4_CRC32_INIT, sb->uuid, sizeof(sb->uuid));
/* Then calculate crc32 checksum block number */
checksum =
ext4_crc32c(checksum, &le64_blocknr, sizeof(le64_blocknr));
/* Finally calculate crc32 checksum against
* the entire xattr block */
checksum =
ext4_crc32c(checksum, header, ext4_sb_get_block_size(sb));
header->h_checksum = orig_checksum;
}
return checksum;
}
#else
#define ext4_xattr_block_checksum(...) 0
#endif
static void ext4_xattr_set_block_checksum(struct ext4_inode_ref *inode_ref,
ext4_fsblk_t blocknr __unused,
struct ext4_xattr_header *header)
{
struct ext4_sblock *sb = &inode_ref->fs->sb;
if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
return;
header->h_checksum =
ext4_xattr_block_checksum(inode_ref, blocknr, header);
}
struct xattr_prefix {
const char *prefix;
uint8_t name_index;
};
static const struct xattr_prefix prefix_tbl[] = {
{"user.", EXT4_XATTR_INDEX_USER},
{"system.posix_acl_access", EXT4_XATTR_INDEX_POSIX_ACL_ACCESS},
{"system.posix_acl_default", EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT},
{"trusted.", EXT4_XATTR_INDEX_TRUSTED},
{"security.", EXT4_XATTR_INDEX_SECURITY},
{"system.", EXT4_XATTR_INDEX_SYSTEM},
{"system.richacl", EXT4_XATTR_INDEX_RICHACL},
{NULL, 0},
};
const char *ext4_extract_xattr_name(const char *full_name, size_t full_name_len,
uint8_t *name_index, size_t *name_len,
bool *found)
{
int i;
ext4_assert(name_index);
ext4_assert(found);
*found = false;
if (!full_name_len) {
if (name_len)
*name_len = 0;
return NULL;
}
for (i = 0; prefix_tbl[i].prefix; i++) {
size_t prefix_len = strlen(prefix_tbl[i].prefix);
if (full_name_len >= prefix_len &&
!memcmp(full_name, prefix_tbl[i].prefix, prefix_len)) {
bool require_name =
prefix_tbl[i].prefix[prefix_len - 1] == '.';
*name_index = prefix_tbl[i].name_index;
if (name_len)
*name_len = full_name_len - prefix_len;
if (!(full_name_len - prefix_len) && require_name)
return NULL;
*found = true;
if (require_name)
return full_name + prefix_len;
return NULL;
}
}
if (name_len)
*name_len = 0;
return NULL;
}
const char *ext4_get_xattr_name_prefix(uint8_t name_index,
size_t *ret_prefix_len)
{
int i;
for (i = 0; prefix_tbl[i].prefix; i++) {
size_t prefix_len = strlen(prefix_tbl[i].prefix);
if (prefix_tbl[i].name_index == name_index) {
if (ret_prefix_len)
*ret_prefix_len = prefix_len;
return prefix_tbl[i].prefix;
}
}
if (ret_prefix_len)
*ret_prefix_len = 0;
return NULL;
}
static const char ext4_xattr_empty_value;
/**
* @brief Insert/Remove/Modify the given entry
*
* @param i The information of the given EA entry
* @param s Search context block
* @param dry_run Do not modify the content of the buffer
*
* @return Return EOK when finished, ENOSPC when there is no enough space
*/
static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
struct ext4_xattr_search *s, bool dry_run)
{
struct ext4_xattr_entry *last;
size_t free, min_offs = (char *)s->end - (char *)s->base,
name_len = i->name_len;
/*
* If the entry is going to be removed but not found, return 0 to
* indicate success.
*/
if (!i->value && s->not_found)
return EOK;
/* Compute min_offs and last. */
last = s->first;
for (; !EXT4_XATTR_IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
if (last->e_value_size) {
size_t offs = to_le16(last->e_value_offs);
if (offs < min_offs)
min_offs = offs;
}
}
/* Calculate free space in the block. */
free = min_offs - ((char *)last - (char *)s->base) - sizeof(uint32_t);
if (!s->not_found)
free += EXT4_XATTR_SIZE(s->here->e_value_size) +
EXT4_XATTR_LEN(s->here->e_name_len);
if (i->value) {
/* See whether there is enough space to hold new entry */
if (free <
EXT4_XATTR_SIZE(i->value_len) + EXT4_XATTR_LEN(name_len))
return ENOSPC;
}
/* Return EOK now if we do not intend to modify the content. */
if (dry_run)
return EOK;
/* First remove the old entry's data part */
if (!s->not_found) {
size_t value_offs = to_le16(s->here->e_value_offs);
void *value = (char *)s->base + value_offs;
void *first_value = (char *)s->base + min_offs;
size_t value_size =
EXT4_XATTR_SIZE(to_le32(s->here->e_value_size));
if (value_offs) {
/* Remove the data part. */
memmove((char *)first_value + value_size, first_value,
(char *)value - (char *)first_value);
/* Zero the gap created */
memset(first_value, 0, value_size);
/*
* Calculate the new min_offs after removal of the old
* entry's data part
*/
min_offs += value_size;
}
/*
* Adjust the value offset of entries which has value offset
* prior to the s->here. The offset of these entries won't be
* shifted if the size of the entry we removed is zero.
*/
for (last = s->first; !EXT4_XATTR_IS_LAST_ENTRY(last);
last = EXT4_XATTR_NEXT(last)) {
size_t offs = to_le16(last->e_value_offs);
/* For zero-value-length entry, offs will be zero. */
if (offs < value_offs)
last->e_value_offs = to_le16(offs + value_size);
}
}
/* If caller wants us to insert... */
if (i->value) {
size_t value_offs;
if (i->value_len)
value_offs = min_offs - EXT4_XATTR_SIZE(i->value_len);
else
value_offs = 0;
if (!s->not_found) {
struct ext4_xattr_entry *here = s->here;
/* Reuse the current entry we have got */
here->e_value_offs = to_le16(value_offs);
here->e_value_size = to_le32(i->value_len);
} else {
/* Insert a new entry */
last->e_name_len = (uint8_t)name_len;
last->e_name_index = i->name_index;
last->e_value_offs = to_le16(value_offs);
last->e_value_block = 0;
last->e_value_size = to_le32(i->value_len);
memcpy(EXT4_XATTR_NAME(last), i->name, name_len);
/* Set valid last entry indicator */
*(uint32_t *)EXT4_XATTR_NEXT(last) = 0;
s->here = last;
}
/* Insert the value's part */
if (value_offs) {
memcpy((char *)s->base + value_offs, i->value,
i->value_len);
/* Clear the padding bytes if there is */
if (EXT4_XATTR_SIZE(i->value_len) != i->value_len)
memset((char *)s->base + value_offs +
i->value_len,
0, EXT4_XATTR_SIZE(i->value_len) -
i->value_len);
}
} else {
size_t shift_offs;
/* Remove the whole entry */
shift_offs = (char *)EXT4_XATTR_NEXT(s->here) - (char *)s->here;
memmove(s->here, EXT4_XATTR_NEXT(s->here),
(char *)last + sizeof(uint32_t) -
(char *)EXT4_XATTR_NEXT(s->here));
/* Zero the gap created */
memset((char *)last - shift_offs + sizeof(uint32_t), 0,
shift_offs);
s->here = NULL;
}
return EOK;
}
static inline bool ext4_xattr_is_empty(struct ext4_xattr_search *s)
{
if (!EXT4_XATTR_IS_LAST_ENTRY(s->first))
return false;
return true;
}
/**
* @brief Find the entry according to given information
*
* @param i The information of the EA entry to be found,
* including name_index, name and the length of name
* @param s Search context block
*/
static void ext4_xattr_find_entry(struct ext4_xattr_info *i,
struct ext4_xattr_search *s)
{
struct ext4_xattr_entry *entry = NULL;
s->not_found = true;
s->here = NULL;
/*
* Find the wanted EA entry by simply comparing the namespace,
* name and the length of name.
*/
for (entry = s->first; !EXT4_XATTR_IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry)) {
size_t name_len = entry->e_name_len;
const char *name = EXT4_XATTR_NAME(entry);
if (name_len == i->name_len &&
entry->e_name_index == i->name_index &&
!memcmp(name, i->name, name_len)) {
s->here = entry;
s->not_found = false;
i->value_len = to_le32(entry->e_value_size);
if (i->value_len)
i->value = (char *)s->base +
to_le16(entry->e_value_offs);
else
i->value = NULL;
return;
}
}
}
/**
* @brief Check whether the xattr block's content is valid
*
* @param inode_ref Inode reference
* @param block The block buffer to be validated
*
* @return true if @block is valid, false otherwise.
*/
static bool ext4_xattr_is_block_valid(struct ext4_inode_ref *inode_ref,
struct ext4_block *block)
{
void *base = block->data,
*end = block->data + ext4_sb_get_block_size(&inode_ref->fs->sb);
size_t min_offs = (char *)end - (char *)base;
struct ext4_xattr_header *header = EXT4_XATTR_BHDR(block);
struct ext4_xattr_entry *entry = EXT4_XATTR_BFIRST(block);
/*
* Check whether the magic number in the header is correct.
*/
if (header->h_magic != to_le32(EXT4_XATTR_MAGIC))
return false;
/*
* The in-kernel filesystem driver only supports 1 block currently.
*/
if (header->h_blocks != to_le32(1))
return false;
/*
* Check if those entries are maliciously corrupted to inflict harm
* upon us.
*/
for (; !EXT4_XATTR_IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry)) {
if (!to_le32(entry->e_value_size) &&
to_le16(entry->e_value_offs))
return false;
if ((char *)base + to_le16(entry->e_value_offs) +
to_le32(entry->e_value_size) >
(char *)end)
return false;
/*
* The name length field should also be correct,
* also there should be an 4-byte zero entry at the
* end.
*/
if ((char *)EXT4_XATTR_NEXT(entry) + sizeof(uint32_t) >
(char *)end)
return false;
if (to_le32(entry->e_value_size)) {
size_t offs = to_le16(entry->e_value_offs);
if (offs < min_offs)
min_offs = offs;
}
}
/*
* Entry field and data field do not override each other.
*/
if ((char *)base + min_offs < (char *)entry + sizeof(uint32_t))
return false;
return true;
}
/**
* @brief Check whether the inode buffer's content is valid
*
* @param inode_ref Inode reference
*
* @return true if the inode buffer is valid, false otherwise.
*/
static bool ext4_xattr_is_ibody_valid(struct ext4_inode_ref *inode_ref)
{
size_t min_offs;
void *base, *end;
struct ext4_fs *fs = inode_ref->fs;
struct ext4_xattr_ibody_header *iheader;
struct ext4_xattr_entry *entry;
size_t inode_size = ext4_get16(&fs->sb, inode_size);
iheader = EXT4_XATTR_IHDR(&fs->sb, inode_ref->inode);
entry = EXT4_XATTR_IFIRST(iheader);
base = iheader;
end = (char *)inode_ref->inode + inode_size;
min_offs = (char *)end - (char *)base;
/*
* Check whether the magic number in the header is correct.
*/
if (iheader->h_magic != to_le32(EXT4_XATTR_MAGIC))
return false;
/*
* Check if those entries are maliciously corrupted to inflict harm
* upon us.
*/
for (; !EXT4_XATTR_IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry)) {
if (!to_le32(entry->e_value_size) &&
to_le16(entry->e_value_offs))
return false;
if ((char *)base + to_le16(entry->e_value_offs) +
to_le32(entry->e_value_size) >
(char *)end)
return false;
/*
* The name length field should also be correct,
* also there should be an 4-byte zero entry at the
* end.
*/
if ((char *)EXT4_XATTR_NEXT(entry) + sizeof(uint32_t) >
(char *)end)
return false;
if (to_le32(entry->e_value_size)) {
size_t offs = to_le16(entry->e_value_offs);
if (offs < min_offs)
min_offs = offs;
}
}
/*
* Entry field and data field do not override each other.
*/
if ((char *)base + min_offs < (char *)entry + sizeof(uint32_t))
return false;
return true;
}
/**
* @brief An EA entry finder for inode buffer
*/
struct ext4_xattr_finder {
/**
* @brief The information of the EA entry to be find
*/
struct ext4_xattr_info i;
/**
* @brief Search context block of the current search
*/
struct ext4_xattr_search s;
/**
* @brief Inode reference to the corresponding inode
*/
struct ext4_inode_ref *inode_ref;
};
static void ext4_xattr_ibody_initialize(struct ext4_inode_ref *inode_ref)
{
struct ext4_xattr_ibody_header *header;
struct ext4_fs *fs = inode_ref->fs;
size_t extra_isize =
ext4_inode_get_extra_isize(&fs->sb, inode_ref->inode);
size_t inode_size = ext4_get16(&fs->sb, inode_size);
if (!extra_isize)
return;
header = EXT4_XATTR_IHDR(&fs->sb, inode_ref->inode);
memset(header, 0, inode_size - EXT4_GOOD_OLD_INODE_SIZE - extra_isize);
header->h_magic = to_le32(EXT4_XATTR_MAGIC);
inode_ref->dirty = true;
}
/**
* @brief Initialize a given xattr block
*
* @param inode_ref Inode reference
* @param block xattr block buffer
*/
static void ext4_xattr_block_initialize(struct ext4_inode_ref *inode_ref,
struct ext4_block *block)
{
struct ext4_xattr_header *header;
struct ext4_fs *fs = inode_ref->fs;
memset(block->data, 0, ext4_sb_get_block_size(&fs->sb));
header = EXT4_XATTR_BHDR(block);
header->h_magic = to_le32(EXT4_XATTR_MAGIC);
header->h_refcount = to_le32(1);
header->h_blocks = to_le32(1);
ext4_trans_set_block_dirty(block->buf);
}
static void ext4_xattr_block_init_search(struct ext4_inode_ref *inode_ref,
struct ext4_xattr_search *s,
struct ext4_block *block)
{
s->base = block->data;
s->end = block->data + ext4_sb_get_block_size(&inode_ref->fs->sb);
s->first = EXT4_XATTR_BFIRST(block);
s->here = NULL;
s->not_found = true;
}
/**
* @brief Find an EA entry inside a xattr block
*
* @param inode_ref Inode reference
* @param finder The caller-provided finder block with
* information filled
* @param block The block buffer to be looked into
*
* @return Return EOK no matter the entry is found or not.
* If the IO operation or the buffer validation failed,
* return other value.
*/
static int ext4_xattr_block_find_entry(struct ext4_inode_ref *inode_ref,
struct ext4_xattr_finder *finder,
struct ext4_block *block)
{
int ret = EOK;
/* Initialize the caller-given finder */
finder->inode_ref = inode_ref;
memset(&finder->s, 0, sizeof(finder->s));
if (ret != EOK)
return ret;
/* Check the validity of the buffer */
if (!ext4_xattr_is_block_valid(inode_ref, block))
return EIO;
ext4_xattr_block_init_search(inode_ref, &finder->s, block);
ext4_xattr_find_entry(&finder->i, &finder->s);
return EOK;
}
/**
* @brief Find an EA entry inside an inode's extra space
*
* @param inode_ref Inode reference
* @param finder The caller-provided finder block with
* information filled
*
* @return Return EOK no matter the entry is found or not.
* If the IO operation or the buffer validation failed,
* return other value.
*/
static int ext4_xattr_ibody_find_entry(struct ext4_inode_ref *inode_ref,
struct ext4_xattr_finder *finder)
{
struct ext4_fs *fs = inode_ref->fs;
struct ext4_xattr_ibody_header *iheader;
size_t extra_isize =
ext4_inode_get_extra_isize(&fs->sb, inode_ref->inode);
size_t inode_size = ext4_get16(&fs->sb, inode_size);
/* Initialize the caller-given finder */
finder->inode_ref = inode_ref;
memset(&finder->s, 0, sizeof(finder->s));
/*
* If there is no extra inode space
* set ext4_xattr_ibody_finder::s::not_found to true and return EOK
*/
if (!extra_isize) {
finder->s.not_found = true;
return EOK;
}
/* Check the validity of the buffer */
if (!ext4_xattr_is_ibody_valid(inode_ref))
return EIO;
iheader = EXT4_XATTR_IHDR(&fs->sb, inode_ref->inode);
finder->s.base = EXT4_XATTR_IFIRST(iheader);
finder->s.end = (char *)inode_ref->inode + inode_size;
finder->s.first = EXT4_XATTR_IFIRST(iheader);
ext4_xattr_find_entry(&finder->i, &finder->s);
return EOK;
}
/**
* @brief Try to allocate a block holding EA entries.
*
* @param inode_ref Inode reference
*
* @return Error code
*/
static int ext4_xattr_try_alloc_block(struct ext4_inode_ref *inode_ref)
{
int ret = EOK;
ext4_fsblk_t xattr_block = 0;
xattr_block =
ext4_inode_get_file_acl(inode_ref->inode, &inode_ref->fs->sb);
/*
* Only allocate a xattr block when there is no xattr block
* used by the inode.
*/
if (!xattr_block) {
ext4_fsblk_t goal = ext4_fs_inode_to_goal_block(inode_ref);
ret = ext4_balloc_alloc_block(inode_ref, goal, &xattr_block);
if (ret != EOK)
goto Finish;
ext4_inode_set_file_acl(inode_ref->inode, &inode_ref->fs->sb,
xattr_block);
}
Finish:
return ret;
}
/**
* @brief Try to free a block holding EA entries.
*
* @param inode_ref Inode reference
*
* @return Error code
*/
static void ext4_xattr_try_free_block(struct ext4_inode_ref *inode_ref)
{
ext4_fsblk_t xattr_block;
xattr_block =
ext4_inode_get_file_acl(inode_ref->inode, &inode_ref->fs->sb);
/*
* Free the xattr block used by the inode when there is one.
*/
if (xattr_block) {
ext4_inode_set_file_acl(inode_ref->inode, &inode_ref->fs->sb,
0);
ext4_balloc_free_block(inode_ref, xattr_block);
inode_ref->dirty = true;
}
}
/**
* @brief Put a list of EA entries into a caller-provided buffer
* In order to make sure that @list buffer can fit in the data,
* the routine should be called twice.
*
* @param inode_ref Inode reference
* @param list A caller-provided buffer to hold a list of EA entries.
* If list == NULL, list_len will contain the size of
* the buffer required to hold these entries
* @param list_len The length of the data written to @list
* @return Error code
*/
int ext4_xattr_list(struct ext4_inode_ref *inode_ref,
struct ext4_xattr_list_entry *list, size_t *list_len)
{
int ret = EOK;
size_t buf_len = 0;
struct ext4_fs *fs = inode_ref->fs;
struct ext4_xattr_ibody_header *iheader;
size_t extra_isize =
ext4_inode_get_extra_isize(&fs->sb, inode_ref->inode);
struct ext4_block block;
bool block_loaded = false;
ext4_fsblk_t xattr_block = 0;
struct ext4_xattr_entry *entry;
struct ext4_xattr_list_entry *list_prev = NULL;
xattr_block = ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
/*
* If there is extra inode space and the xattr buffer in the
* inode is valid.
*/
if (extra_isize && ext4_xattr_is_ibody_valid(inode_ref)) {
iheader = EXT4_XATTR_IHDR(&fs->sb, inode_ref->inode);
entry = EXT4_XATTR_IFIRST(iheader);
/*
* The format of the list should be like this:
*
* name_len indicates the length in bytes of the name
* of the EA entry. The string is null-terminated.
*
* list->name => (char *)(list + 1);
* list->next => (void *)((char *)(list + 1) + name_len + 1);
*/
for (; !EXT4_XATTR_IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry)) {
size_t name_len = entry->e_name_len;
if (list) {
list->name_index = entry->e_name_index;
list->name_len = name_len;
list->name = (char *)(list + 1);
memcpy(list->name, EXT4_XATTR_NAME(entry),
list->name_len);
if (list_prev)
list_prev->next = list;
list_prev = list;
list = (struct ext4_xattr_list_entry
*)(list->name + name_len + 1);
}
/*
* Size calculation by pointer arithmetics.
*/
buf_len +=
(char *)((struct ext4_xattr_list_entry *)0 + 1) +
name_len + 1 -
(char *)(struct ext4_xattr_list_entry *)0;
}
}
/*
* If there is a xattr block used by the inode
*/
if (xattr_block) {
ret = ext4_trans_block_get(fs->bdev, &block, xattr_block);
if (ret != EOK)
goto out;
block_loaded = true;
/*
* As we don't allow the content in the block being invalid,
* bail out.
*/
if (!ext4_xattr_is_block_valid(inode_ref, &block)) {
ret = EIO;
goto out;
}
entry = EXT4_XATTR_BFIRST(&block);
/*
* The format of the list should be like this:
*
* name_len indicates the length in bytes of the name
* of the EA entry. The string is null-terminated.
*
* list->name => (char *)(list + 1);
* list->next => (void *)((char *)(list + 1) + name_len + 1);
*
* Same as above actually.
*/
for (; !EXT4_XATTR_IS_LAST_ENTRY(entry);
entry = EXT4_XATTR_NEXT(entry)) {
size_t name_len = entry->e_name_len;
if (list) {
list->name_index = entry->e_name_index;
list->name_len = name_len;
list->name = (char *)(list + 1);
memcpy(list->name, EXT4_XATTR_NAME(entry),
list->name_len);
if (list_prev)
list_prev->next = list;
list_prev = list;
list = (struct ext4_xattr_list_entry
*)(list->name + name_len + 1);
}
/*
* Size calculation by pointer arithmetics.
*/
buf_len +=
(char *)((struct ext4_xattr_list_entry *)0 + 1) +
name_len + 1 -
(char *)(struct ext4_xattr_list_entry *)0;
}
}
if (list_prev)
list_prev->next = NULL;
out:
if (ret == EOK && list_len)
*list_len = buf_len;
if (block_loaded)
ext4_block_set(fs->bdev, &block);
return ret;
}
/**
* @brief Query EA entry's value with given name-index and name
*
* @param inode_ref Inode reference
* @param name_index Name-index
* @param name Name of the EA entry to be queried
* @param name_len Length of name in bytes
* @param buf Output buffer to hold content
* @param buf_len Output buffer's length
* @param data_len The length of data of the EA entry found
*
* @return Error code
*/
int ext4_xattr_get(struct ext4_inode_ref *inode_ref, uint8_t name_index,
const char *name, size_t name_len, void *buf, size_t buf_len,
size_t *data_len)
{
int ret = EOK;
struct ext4_xattr_finder ibody_finder;
struct ext4_xattr_finder block_finder;
struct ext4_xattr_info i;
size_t value_len = 0;
size_t value_offs = 0;
struct ext4_fs *fs = inode_ref->fs;
ext4_fsblk_t xattr_block;
xattr_block = ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
i.name_index = name_index;
i.name = name;
i.name_len = name_len;
i.value = 0;
i.value_len = 0;
if (data_len)
*data_len = 0;
ibody_finder.i = i;
ret = ext4_xattr_ibody_find_entry(inode_ref, &ibody_finder);
if (ret != EOK)
goto out;
if (!ibody_finder.s.not_found) {
value_len = to_le32(ibody_finder.s.here->e_value_size);
value_offs = to_le32(ibody_finder.s.here->e_value_offs);
if (buf_len && buf) {
void *data_loc =
(char *)ibody_finder.s.base + value_offs;
memcpy(buf, data_loc,
(buf_len < value_len) ? buf_len : value_len);
}
} else {
struct ext4_block block;
/* Return ENODATA if there is no EA block */
if (!xattr_block) {
ret = ENODATA;
goto out;
}
block_finder.i = i;
ret = ext4_trans_block_get(fs->bdev, &block, xattr_block);
if (ret != EOK)
goto out;
ret = ext4_xattr_block_find_entry(inode_ref, &block_finder,
&block);
if (ret != EOK) {
ext4_block_set(fs->bdev, &block);
goto out;
}
/* Return ENODATA if entry is not found */
if (block_finder.s.not_found) {
ext4_block_set(fs->bdev, &block);
ret = ENODATA;
goto out;
}
value_len = to_le32(block_finder.s.here->e_value_size);
value_offs = to_le32(block_finder.s.here->e_value_offs);
if (buf_len && buf) {
void *data_loc =
(char *)block_finder.s.base + value_offs;
memcpy(buf, data_loc,
(buf_len < value_len) ? buf_len : value_len);
}
/*
* Free the xattr block buffer returned by
* ext4_xattr_block_find_entry.
*/
ext4_block_set(fs->bdev, &block);
}
out:
if (ret == EOK && data_len)
*data_len = value_len;
return ret;
}
/**
* @brief Try to copy the content of an xattr block to a newly-allocated
* block. If the operation fails, the block buffer provided by
* caller will be freed
*
* @param inode_ref Inode reference
* @param block The block buffer reference
* @param new_block The newly-allocated block buffer reference
* @param orig_block The block number of @block
* @param allocated a new block is allocated
*
* @return Error code
*/
static int ext4_xattr_copy_new_block(struct ext4_inode_ref *inode_ref,
struct ext4_block *block,
struct ext4_block *new_block,
ext4_fsblk_t *orig_block, bool *allocated)
{
int ret = EOK;
ext4_fsblk_t xattr_block = 0;
struct ext4_xattr_header *header;
struct ext4_fs *fs = inode_ref->fs;
header = EXT4_XATTR_BHDR(block);
if (orig_block)
*orig_block = block->lb_id;
if (allocated)
*allocated = false;
/* Only do copy when a block is referenced by more than one inode. */
if (to_le32(header->h_refcount) > 1) {
ext4_fsblk_t goal = ext4_fs_inode_to_goal_block(inode_ref);
/* Allocate a new block to be used by this inode */
ret = ext4_balloc_alloc_block(inode_ref, goal, &xattr_block);
if (ret != EOK)
goto out;
ret = ext4_trans_block_get(fs->bdev, new_block, xattr_block);
if (ret != EOK)
goto out;
/* Copy the content of the whole block */
memcpy(new_block->data, block->data,
ext4_sb_get_block_size(&inode_ref->fs->sb));
/*
* Decrement the reference count of the original xattr block
* by one
*/
header->h_refcount = to_le32(to_le32(header->h_refcount) - 1);
ext4_trans_set_block_dirty(block->buf);
ext4_trans_set_block_dirty(new_block->buf);
header = EXT4_XATTR_BHDR(new_block);
header->h_refcount = to_le32(1);
if (allocated)
*allocated = true;
}
out:
if (xattr_block) {
if (ret != EOK)
ext4_balloc_free_block(inode_ref, xattr_block);
else {
/*
* Modify the in-inode pointer to point to the new xattr block
*/
ext4_inode_set_file_acl(inode_ref->inode, &fs->sb, xattr_block);
inode_ref->dirty = true;
}
}
return ret;
}
/**
* @brief Given an EA entry's name, remove the EA entry
*
* @param inode_ref Inode reference
* @param name_index Name-index
* @param name Name of the EA entry to be removed
* @param name_len Length of name in bytes
*
* @return Error code
*/
int ext4_xattr_remove(struct ext4_inode_ref *inode_ref, uint8_t name_index,
const char *name, size_t name_len)
{
int ret = EOK;
struct ext4_block block;
struct ext4_xattr_finder ibody_finder;
struct ext4_xattr_finder block_finder;
bool use_block = false;
bool block_loaded = false;
struct ext4_xattr_info i;
struct ext4_fs *fs = inode_ref->fs;
ext4_fsblk_t xattr_block;
xattr_block = ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
i.name_index = name_index;
i.name = name;
i.name_len = name_len;
i.value = NULL;
i.value_len = 0;
ibody_finder.i = i;
block_finder.i = i;
ret = ext4_xattr_ibody_find_entry(inode_ref, &ibody_finder);
if (ret != EOK)
goto out;
if (ibody_finder.s.not_found && xattr_block) {
ret = ext4_trans_block_get(fs->bdev, &block, xattr_block);
if (ret != EOK)
goto out;
block_loaded = true;
block_finder.i = i;
ret = ext4_xattr_block_find_entry(inode_ref, &block_finder,
&block);
if (ret != EOK)
goto out;
/* Return ENODATA if entry is not found */
if (block_finder.s.not_found) {
ret = ENODATA;
goto out;
}
use_block = true;
}
if (use_block) {
bool allocated = false;
struct ext4_block new_block;
/*
* There will be no effect when the xattr block is only referenced
* once.
*/
ret = ext4_xattr_copy_new_block(inode_ref, &block, &new_block,
&xattr_block, &allocated);
if (ret != EOK)
goto out;
if (!allocated) {
/* Prevent double-freeing */
block_loaded = false;
new_block = block;
}
ret = ext4_xattr_block_find_entry(inode_ref, &block_finder,
&new_block);
if (ret != EOK)
goto out;
/* Now remove the entry */
ext4_xattr_set_entry(&i, &block_finder.s, false);
if (ext4_xattr_is_empty(&block_finder.s)) {
ext4_block_set(fs->bdev, &new_block);
ext4_xattr_try_free_block(inode_ref);
} else {
struct ext4_xattr_header *header =
EXT4_XATTR_BHDR(&new_block);
header = EXT4_XATTR_BHDR(&new_block);
ext4_assert(block_finder.s.first);
ext4_xattr_rehash(header, block_finder.s.first);
ext4_xattr_set_block_checksum(inode_ref,
block.lb_id,
header);
ext4_trans_set_block_dirty(new_block.buf);
ext4_block_set(fs->bdev, &new_block);
}
} else {
/* Now remove the entry */
ext4_xattr_set_entry(&i, &block_finder.s, false);
inode_ref->dirty = true;
}
out:
if (block_loaded)
ext4_block_set(fs->bdev, &block);
return ret;
}
/**
* @brief Insert/overwrite an EA entry into/in a xattr block
*
* @param inode_ref Inode reference
* @param i The information of the given EA entry
*
* @return Error code
*/
static int ext4_xattr_block_set(struct ext4_inode_ref *inode_ref,
struct ext4_xattr_info *i,
bool no_insert)
{
int ret = EOK;
bool allocated = false;
struct ext4_fs *fs = inode_ref->fs;
struct ext4_block block, new_block;
ext4_fsblk_t orig_xattr_block;
orig_xattr_block = ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
ext4_assert(i->value);
if (!orig_xattr_block) {
struct ext4_xattr_search s;
struct ext4_xattr_header *header;
/* If insertion of new entry is not allowed... */
if (no_insert) {
ret = ENODATA;
goto out;
}
ret = ext4_xattr_try_alloc_block(inode_ref);
if (ret != EOK)
goto out;
orig_xattr_block =
ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
ret = ext4_trans_block_get(fs->bdev, &block, orig_xattr_block);
if (ret != EOK) {
ext4_xattr_try_free_block(inode_ref);
goto out;
}
ext4_xattr_block_initialize(inode_ref, &block);
ext4_xattr_block_init_search(inode_ref, &s, &block);
ret = ext4_xattr_set_entry(i, &s, false);
if (ret == EOK) {
header = EXT4_XATTR_BHDR(&block);
ext4_assert(s.here);
ext4_assert(s.first);
ext4_xattr_compute_hash(header, s.here);
ext4_xattr_rehash(header, s.first);
ext4_xattr_set_block_checksum(inode_ref,
block.lb_id,
header);
ext4_trans_set_block_dirty(block.buf);
}
ext4_block_set(fs->bdev, &block);
if (ret != EOK)
ext4_xattr_try_free_block(inode_ref);
} else {
struct ext4_xattr_finder finder;
struct ext4_xattr_header *header;
finder.i = *i;
ret = ext4_trans_block_get(fs->bdev, &block, orig_xattr_block);
if (ret != EOK)
goto out;
header = EXT4_XATTR_BHDR(&block);
/*
* Consider the following case when insertion of new
* entry is not allowed
*/
if (to_le32(header->h_refcount) > 1 && no_insert) {
/*
* There are other people referencing the
* same xattr block
*/
ret = ext4_xattr_block_find_entry(inode_ref, &finder, &block);
if (ret != EOK) {
ext4_block_set(fs->bdev, &block);
goto out;
}
if (finder.s.not_found) {
ext4_block_set(fs->bdev, &block);
ret = ENODATA;
goto out;
}
}
/*
* There will be no effect when the xattr block is only referenced
* once.
*/
ret = ext4_xattr_copy_new_block(inode_ref, &block, &new_block,
&orig_xattr_block, &allocated);
if (ret != EOK) {
ext4_block_set(fs->bdev, &block);
goto out;
}
if (allocated) {
ext4_block_set(fs->bdev, &block);
new_block = block;
}
ret = ext4_xattr_block_find_entry(inode_ref, &finder, &block);
if (ret != EOK) {
ext4_block_set(fs->bdev, &block);
goto out;
}
ret = ext4_xattr_set_entry(i, &finder.s, false);
if (ret == EOK) {
header = EXT4_XATTR_BHDR(&block);
ext4_assert(finder.s.here);
ext4_assert(finder.s.first);
ext4_xattr_compute_hash(header, finder.s.here);
ext4_xattr_rehash(header, finder.s.first);
ext4_xattr_set_block_checksum(inode_ref,
block.lb_id,
header);
ext4_trans_set_block_dirty(block.buf);
}
ext4_block_set(fs->bdev, &block);
}
out:
return ret;
}
/**
* @brief Remove an EA entry from a xattr block
*
* @param inode_ref Inode reference
* @param i The information of the given EA entry
*
* @return Error code
*/
static int ext4_xattr_block_remove(struct ext4_inode_ref *inode_ref,
struct ext4_xattr_info *i)
{
int ret = EOK;
bool allocated = false;
const void *value = i->value;
struct ext4_fs *fs = inode_ref->fs;
struct ext4_xattr_finder finder;
struct ext4_block block, new_block;
struct ext4_xattr_header *header;
ext4_fsblk_t orig_xattr_block;
orig_xattr_block = ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
ext4_assert(orig_xattr_block);
ret = ext4_trans_block_get(fs->bdev, &block, orig_xattr_block);
if (ret != EOK)
goto out;
/*
* There will be no effect when the xattr block is only referenced
* once.
*/
ret = ext4_xattr_copy_new_block(inode_ref, &block, &new_block,
&orig_xattr_block, &allocated);
if (ret != EOK) {
ext4_block_set(fs->bdev, &block);
goto out;
}
if (allocated) {
ext4_block_set(fs->bdev, &block);
block = new_block;
}
ext4_xattr_block_find_entry(inode_ref, &finder, &block);
if (!finder.s.not_found) {
i->value = NULL;
ret = ext4_xattr_set_entry(i, &finder.s, false);
i->value = value;
header = EXT4_XATTR_BHDR(&block);
ext4_assert(finder.s.first);
ext4_xattr_rehash(header, finder.s.first);
ext4_xattr_set_block_checksum(inode_ref,
block.lb_id,
header);
ext4_trans_set_block_dirty(block.buf);
}
ext4_block_set(fs->bdev, &block);
out:
return ret;
}
/**
* @brief Insert an EA entry into a given inode reference
*
* @param inode_ref Inode reference
* @param name_index Name-index
* @param name Name of the EA entry to be inserted
* @param name_len Length of name in bytes
* @param value Input buffer to hold content
* @param value_len Length of input content
*
* @return Error code
*/
int ext4_xattr_set(struct ext4_inode_ref *inode_ref, uint8_t name_index,
const char *name, size_t name_len, const void *value,
size_t value_len)
{
int ret = EOK;
struct ext4_fs *fs = inode_ref->fs;
struct ext4_xattr_finder ibody_finder;
struct ext4_xattr_info i;
bool block_found = false;
ext4_fsblk_t orig_xattr_block;
size_t extra_isize =
ext4_inode_get_extra_isize(&fs->sb, inode_ref->inode);
i.name_index = name_index;
i.name = name;
i.name_len = name_len;
i.value = (value_len) ? value : &ext4_xattr_empty_value;
i.value_len = value_len;
ibody_finder.i = i;
orig_xattr_block = ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
/*
* Even if entry is not found, search context block inside the
* finder is still valid and can be used to insert entry.
*/
ret = ext4_xattr_ibody_find_entry(inode_ref, &ibody_finder);
if (ret != EOK) {
ext4_xattr_ibody_initialize(inode_ref);
ext4_xattr_ibody_find_entry(inode_ref, &ibody_finder);
}
if (ibody_finder.s.not_found) {
if (orig_xattr_block) {
block_found = true;
ret = ext4_xattr_block_set(inode_ref, &i, true);
if (ret == ENOSPC)
goto try_insert;
else if (ret == ENODATA)
goto try_insert;
else if (ret != EOK)
goto out;
} else
goto try_insert;
} else {
try_insert:
/* Only try to set entry in ibody if inode is sufficiently large */
if (extra_isize)
ret = ext4_xattr_set_entry(&i, &ibody_finder.s, false);
else
ret = ENOSPC;
if (ret == ENOSPC) {
if (!block_found) {
ret = ext4_xattr_block_set(inode_ref, &i, false);
ibody_finder.i.value = NULL;
ext4_xattr_set_entry(&ibody_finder.i,
&ibody_finder.s, false);
inode_ref->dirty = true;
}
} else if (ret == EOK) {
if (block_found)
ret = ext4_xattr_block_remove(inode_ref, &i);
inode_ref->dirty = true;
}
}
out:
return ret;
}
/**
* @}
*/