/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <sys/stat.h>
#include <string.h>
#include <stdio.h>
#ifdef __ANDROID__
#include <linux/capability.h>
#else
#include <private/android_filesystem_capability.h>
#endif
#define XATTR_SELINUX_SUFFIX "selinux"
#define XATTR_CAPS_SUFFIX "capability"
#include "ext4_utils.h"
#include "make_ext4fs.h"
#include "allocate.h"
#include "contents.h"
#include "extent.h"
#include "indirect.h"
#ifdef USE_MINGW
#define S_IFLNK 0 /* used by make_link, not needed under mingw */
#endif
static struct block_allocation* saved_allocation_head = NULL;
struct block_allocation* get_saved_allocation_chain() {
return saved_allocation_head;
}
static u32 dentry_size(u32 entries, struct dentry *dentries)
{
u32 len = 24;
unsigned int i;
unsigned int dentry_len;
for (i = 0; i < entries; i++) {
dentry_len = 8 + EXT4_ALIGN(strlen(dentries[i].filename), 4);
if (len % info.block_size + dentry_len > info.block_size)
len += info.block_size - (len % info.block_size);
len += dentry_len;
}
return len;
}
static struct ext4_dir_entry_2 *add_dentry(u8 *data, u32 *offset,
struct ext4_dir_entry_2 *prev, u32 inode, const char *name,
u8 file_type)
{
u8 name_len = strlen(name);
u16 rec_len = 8 + EXT4_ALIGN(name_len, 4);
struct ext4_dir_entry_2 *dentry;
u32 start_block = *offset / info.block_size;
u32 end_block = (*offset + rec_len - 1) / info.block_size;
if (start_block != end_block) {
/* Adding this dentry will cross a block boundary, so pad the previous
dentry to the block boundary */
if (!prev)
critical_error("no prev");
prev->rec_len += end_block * info.block_size - *offset;
*offset = end_block * info.block_size;
}
dentry = (struct ext4_dir_entry_2 *)(data + *offset);
dentry->inode = inode;
dentry->rec_len = rec_len;
dentry->name_len = name_len;
dentry->file_type = file_type;
memcpy(dentry->name, name, name_len);
*offset += rec_len;
return dentry;
}
/* Creates a directory structure for an array of directory entries, dentries,
and stores the location of the structure in an inode. The new inode's
.. link is set to dir_inode_num. Stores the location of the inode number
of each directory entry into dentries[i].inode, to be filled in later
when the inode for the entry is allocated. Returns the inode number of the
new directory */
u32 make_directory(u32 dir_inode_num, u32 entries, struct dentry *dentries,
u32 dirs)
{
struct ext4_inode *inode;
u32 blocks;
u32 len;
u32 offset = 0;
u32 inode_num;
u8 *data;
unsigned int i;
struct ext4_dir_entry_2 *dentry;
blocks = DIV_ROUND_UP(dentry_size(entries, dentries), info.block_size);
len = blocks * info.block_size;
if (dir_inode_num) {
inode_num = allocate_inode(info);
} else {
dir_inode_num = EXT4_ROOT_INO;
inode_num = EXT4_ROOT_INO;
}
if (inode_num == EXT4_ALLOCATE_FAILED) {
error("failed to allocate inode\n");
return EXT4_ALLOCATE_FAILED;
}
add_directory(inode_num);
inode = get_inode(inode_num);
if (inode == NULL) {
error("failed to get inode %u", inode_num);
return EXT4_ALLOCATE_FAILED;
}
data = inode_allocate_data_extents(inode, len, len);
if (data == NULL) {
error("failed to allocate %u extents", len);
return EXT4_ALLOCATE_FAILED;
}
inode->i_mode = S_IFDIR;
inode->i_links_count = dirs + 2;
inode->i_flags |= aux_info.default_i_flags;
dentry = NULL;
dentry = add_dentry(data, &offset, NULL, inode_num, ".", EXT4_FT_DIR);
if (!dentry) {
error("failed to add . directory");
return EXT4_ALLOCATE_FAILED;
}
dentry = add_dentry(data, &offset, dentry, dir_inode_num, "..", EXT4_FT_DIR);
if (!dentry) {
error("failed to add .. directory");
return EXT4_ALLOCATE_FAILED;
}
for (i = 0; i < entries; i++) {
dentry = add_dentry(data, &offset, dentry, 0,
dentries[i].filename, dentries[i].file_type);
if (offset > len || (offset == len && i != entries - 1))
critical_error("internal error: dentry for %s ends at %d, past %d\n",
dentries[i].filename, offset, len);
dentries[i].inode = &dentry->inode;
if (!dentry) {
error("failed to add directory");
return EXT4_ALLOCATE_FAILED;
}
}
/* pad the last dentry out to the end of the block */
dentry->rec_len += len - offset;
return inode_num;
}
/* Creates a file on disk. Returns the inode number of the new file */
u32 make_file(const char *filename, u64 len)
{
struct ext4_inode *inode;
u32 inode_num;
inode_num = allocate_inode(info);
if (inode_num == EXT4_ALLOCATE_FAILED) {
error("failed to allocate inode\n");
return EXT4_ALLOCATE_FAILED;
}
inode = get_inode(inode_num);
if (inode == NULL) {
error("failed to get inode %u", inode_num);
return EXT4_ALLOCATE_FAILED;
}
if (len > 0) {
struct block_allocation* alloc = inode_allocate_file_extents(inode, len, filename);
if (alloc) {
alloc->filename = strdup(filename);
alloc->next = saved_allocation_head;
saved_allocation_head = alloc;
}
}
inode->i_mode = S_IFREG;
inode->i_links_count = 1;
inode->i_flags |= aux_info.default_i_flags;
return inode_num;
}
/* Creates a file on disk. Returns the inode number of the new file */
u32 make_link(const char *link)
{
struct ext4_inode *inode;
u32 inode_num;
u32 len = strlen(link);
inode_num = allocate_inode(info);
if (inode_num == EXT4_ALLOCATE_FAILED) {
error("failed to allocate inode\n");
return EXT4_ALLOCATE_FAILED;
}
inode = get_inode(inode_num);
if (inode == NULL) {
error("failed to get inode %u", inode_num);
return EXT4_ALLOCATE_FAILED;
}
inode->i_mode = S_IFLNK;
inode->i_links_count = 1;
inode->i_flags |= aux_info.default_i_flags;
inode->i_size_lo = len;
if (len + 1 <= sizeof(inode->i_block)) {
/* Fast symlink */
memcpy((char*)inode->i_block, link, len);
} else {
u8 *data = inode_allocate_data_indirect(inode, info.block_size, info.block_size);
memcpy(data, link, len);
inode->i_blocks_lo = info.block_size / 512;
}
return inode_num;
}
int inode_set_permissions(u32 inode_num, u16 mode, u16 uid, u16 gid, u32 mtime)
{
struct ext4_inode *inode = get_inode(inode_num);
if (!inode)
return -1;
inode->i_mode |= mode;
inode->i_uid = uid;
inode->i_gid = gid;
inode->i_mtime = mtime;
inode->i_atime = mtime;
inode->i_ctime = mtime;
return 0;
}
/*
* Returns the amount of free space available in the specified
* xattr region
*/
static size_t xattr_free_space(struct ext4_xattr_entry *entry, char *end)
{
end -= sizeof(uint32_t); /* Required four null bytes */
while(!IS_LAST_ENTRY(entry) && (((char *) entry) < end)) {
end -= EXT4_XATTR_SIZE(le32_to_cpu(entry->e_value_size));
entry = EXT4_XATTR_NEXT(entry);
}
if (((char *) entry) > end) {
error("unexpected read beyond end of xattr space");
return 0;
}
return end - ((char *) entry);
}
/*
* Returns a pointer to the free space immediately after the
* last xattr element
*/
static struct ext4_xattr_entry* xattr_get_last(struct ext4_xattr_entry *entry)
{
for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
// skip entry
}
return entry;
}
/*
* assert that the elements in the ext4 xattr section are in sorted order
*
* The ext4 filesystem requires extended attributes to be sorted when
* they're not stored in the inode. The kernel ext4 code uses the following
* sorting algorithm:
*
* 1) First sort extended attributes by their name_index. For example,
* EXT4_XATTR_INDEX_USER (1) comes before EXT4_XATTR_INDEX_SECURITY (6).
* 2) If the name_indexes are equal, then sorting is based on the length
* of the name. For example, XATTR_SELINUX_SUFFIX ("selinux") comes before
* XATTR_CAPS_SUFFIX ("capability") because "selinux" is shorter than "capability"
* 3) If the name_index and name_length are equal, then memcmp() is used to determine
* which name comes first. For example, "selinux" would come before "yelinux".
*
* This method is intended to implement the sorting function defined in
* the Linux kernel file fs/ext4/xattr.c function ext4_xattr_find_entry().
*/
static void xattr_assert_sane(struct ext4_xattr_entry *entry)
{
for( ; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
if (IS_LAST_ENTRY(next)) {
return;
}
int cmp = next->e_name_index - entry->e_name_index;
if (cmp == 0)
cmp = next->e_name_len - entry->e_name_len;
if (cmp == 0)
cmp = memcmp(next->e_name, entry->e_name, next->e_name_len);
if (cmp < 0) {
error("BUG: extended attributes are not sorted\n");
return;
}
if (cmp == 0) {
error("BUG: duplicate extended attributes detected\n");
return;
}
}
}
#define NAME_HASH_SHIFT 5
#define VALUE_HASH_SHIFT 16
static void ext4_xattr_hash_entry(struct ext4_xattr_header *header,
struct ext4_xattr_entry *entry)
{
u32 hash = 0;
char *name = entry->e_name;
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) {
u32 *value = (u32 *)((char *)header +
le16_to_cpu(entry->e_value_offs));
for (n = (le32_to_cpu(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)) ^
le32_to_cpu(*value++);
}
}
entry->e_hash = cpu_to_le32(hash);
}
#undef NAME_HASH_SHIFT
#undef VALUE_HASH_SHIFT
static struct ext4_xattr_entry* xattr_addto_range(
void *block_start,
void *block_end,
struct ext4_xattr_entry *first,
int name_index,
const char *name,
const void *value,
size_t value_len)
{
size_t name_len = strlen(name);
if (name_len > 255)
return NULL;
size_t available_size = xattr_free_space(first, block_end);
size_t needed_size = EXT4_XATTR_LEN(name_len) + EXT4_XATTR_SIZE(value_len);
if (needed_size > available_size)
return NULL;
struct ext4_xattr_entry *new_entry = xattr_get_last(first);
memset(new_entry, 0, EXT4_XATTR_LEN(name_len));
new_entry->e_name_len = name_len;
new_entry->e_name_index = name_index;
memcpy(new_entry->e_name, name, name_len);
new_entry->e_value_block = 0;
new_entry->e_value_size = cpu_to_le32(value_len);
char *val = (char *) new_entry + available_size - EXT4_XATTR_SIZE(value_len);
size_t e_value_offs = val - (char *) block_start;
new_entry->e_value_offs = cpu_to_le16(e_value_offs);
memset(val, 0, EXT4_XATTR_SIZE(value_len));
memcpy(val, value, value_len);
xattr_assert_sane(first);
return new_entry;
}
static int xattr_addto_inode(struct ext4_inode *inode, int name_index,
const char *name, const void *value, size_t value_len)
{
struct ext4_xattr_ibody_header *hdr = (struct ext4_xattr_ibody_header *) (inode + 1);
struct ext4_xattr_entry *first = (struct ext4_xattr_entry *) (hdr + 1);
char *block_end = ((char *) inode) + info.inode_size;
struct ext4_xattr_entry *result =
xattr_addto_range(first, block_end, first, name_index, name, value, value_len);
if (result == NULL)
return -1;
hdr->h_magic = cpu_to_le32(EXT4_XATTR_MAGIC);
inode->i_extra_isize = cpu_to_le16(sizeof(struct ext4_inode) - EXT4_GOOD_OLD_INODE_SIZE);
return 0;
}
static int xattr_addto_block(struct ext4_inode *inode, int name_index,
const char *name, const void *value, size_t value_len)
{
struct ext4_xattr_header *header = get_xattr_block_for_inode(inode);
if (!header)
return -1;
struct ext4_xattr_entry *first = (struct ext4_xattr_entry *) (header + 1);
char *block_end = ((char *) header) + info.block_size;
struct ext4_xattr_entry *result =
xattr_addto_range(header, block_end, first, name_index, name, value, value_len);
if (result == NULL)
return -1;
ext4_xattr_hash_entry(header, result);
return 0;
}
static int xattr_add(u32 inode_num, int name_index, const char *name,
const void *value, size_t value_len)
{
if (!value)
return 0;
struct ext4_inode *inode = get_inode(inode_num);
if (!inode)
return -1;
int result = xattr_addto_inode(inode, name_index, name, value, value_len);
if (result != 0) {
result = xattr_addto_block(inode, name_index, name, value, value_len);
}
return result;
}
int inode_set_selinux(u32 inode_num, const char *secon)
{
if (!secon)
return 0;
return xattr_add(inode_num, EXT4_XATTR_INDEX_SECURITY,
XATTR_SELINUX_SUFFIX, secon, strlen(secon) + 1);
}
int inode_set_capabilities(u32 inode_num, uint64_t capabilities) {
if (capabilities == 0)
return 0;
struct vfs_cap_data cap_data;
memset(&cap_data, 0, sizeof(cap_data));
cap_data.magic_etc = VFS_CAP_REVISION | VFS_CAP_FLAGS_EFFECTIVE;
cap_data.data[0].permitted = (uint32_t) (capabilities & 0xffffffff);
cap_data.data[0].inheritable = 0;
cap_data.data[1].permitted = (uint32_t) (capabilities >> 32);
cap_data.data[1].inheritable = 0;
return xattr_add(inode_num, EXT4_XATTR_INDEX_SECURITY,
XATTR_CAPS_SUFFIX, &cap_data, sizeof(cap_data));
}