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linux/fs/fat/namei_msdos.c
Christian Brauner e18275ae55
fs: port ->rename() to pass mnt_idmap 
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:26 +01:00

690 lines
17 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/msdos/namei.c
*
* Written 1992,1993 by Werner Almesberger
* Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
* Rewritten for constant inumbers 1999 by Al Viro
*/
#include <linux/module.h>
#include <linux/iversion.h>
#include "fat.h"
/* Characters that are undesirable in an MS-DOS file name */
static unsigned char bad_chars[] = "*?<>|\"";
static unsigned char bad_if_strict[] = "+=,; ";
/***** Formats an MS-DOS file name. Rejects invalid names. */
static int msdos_format_name(const unsigned char *name, int len,
unsigned char *res, struct fat_mount_options *opts)
/*
* name is the proposed name, len is its length, res is
* the resulting name, opts->name_check is either (r)elaxed,
* (n)ormal or (s)trict, opts->dotsOK allows dots at the
* beginning of name (for hidden files)
*/
{
unsigned char *walk;
unsigned char c;
int space;
if (name[0] == '.') { /* dotfile because . and .. already done */
if (opts->dotsOK) {
/* Get rid of dot - test for it elsewhere */
name++;
len--;
} else
return -EINVAL;
}
/*
* disallow names that _really_ start with a dot
*/
space = 1;
c = 0;
for (walk = res; len && walk - res < 8; walk++) {
c = *name++;
len--;
if (opts->name_check != 'r' && strchr(bad_chars, c))
return -EINVAL;
if (opts->name_check == 's' && strchr(bad_if_strict, c))
return -EINVAL;
if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
return -EINVAL;
if (c < ' ' || c == ':' || c == '\\')
return -EINVAL;
/*
* 0xE5 is legal as a first character, but we must substitute
* 0x05 because 0xE5 marks deleted files. Yes, DOS really
* does this.
* It seems that Microsoft hacked DOS to support non-US
* characters after the 0xE5 character was already in use to
* mark deleted files.
*/
if ((res == walk) && (c == 0xE5))
c = 0x05;
if (c == '.')
break;
space = (c == ' ');
*walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c;
}
if (space)
return -EINVAL;
if (opts->name_check == 's' && len && c != '.') {
c = *name++;
len--;
if (c != '.')
return -EINVAL;
}
while (c != '.' && len--)
c = *name++;
if (c == '.') {
while (walk - res < 8)
*walk++ = ' ';
while (len > 0 && walk - res < MSDOS_NAME) {
c = *name++;
len--;
if (opts->name_check != 'r' && strchr(bad_chars, c))
return -EINVAL;
if (opts->name_check == 's' &&
strchr(bad_if_strict, c))
return -EINVAL;
if (c < ' ' || c == ':' || c == '\\')
return -EINVAL;
if (c == '.') {
if (opts->name_check == 's')
return -EINVAL;
break;
}
if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
return -EINVAL;
space = c == ' ';
if (!opts->nocase && c >= 'a' && c <= 'z')
*walk++ = c - 32;
else
*walk++ = c;
}
if (space)
return -EINVAL;
if (opts->name_check == 's' && len)
return -EINVAL;
}
while (walk - res < MSDOS_NAME)
*walk++ = ' ';
return 0;
}
/***** Locates a directory entry. Uses unformatted name. */
static int msdos_find(struct inode *dir, const unsigned char *name, int len,
struct fat_slot_info *sinfo)
{
struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
unsigned char msdos_name[MSDOS_NAME];
int err;
err = msdos_format_name(name, len, msdos_name, &sbi->options);
if (err)
return -ENOENT;
err = fat_scan(dir, msdos_name, sinfo);
if (!err && sbi->options.dotsOK) {
if (name[0] == '.') {
if (!(sinfo->de->attr & ATTR_HIDDEN))
err = -ENOENT;
} else {
if (sinfo->de->attr & ATTR_HIDDEN)
err = -ENOENT;
}
if (err)
brelse(sinfo->bh);
}
return err;
}
/*
* Compute the hash for the msdos name corresponding to the dentry.
* Note: if the name is invalid, we leave the hash code unchanged so
* that the existing dentry can be used. The msdos fs routines will
* return ENOENT or EINVAL as appropriate.
*/
static int msdos_hash(const struct dentry *dentry, struct qstr *qstr)
{
struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
unsigned char msdos_name[MSDOS_NAME];
int error;
error = msdos_format_name(qstr->name, qstr->len, msdos_name, options);
if (!error)
qstr->hash = full_name_hash(dentry, msdos_name, MSDOS_NAME);
return 0;
}
/*
* Compare two msdos names. If either of the names are invalid,
* we fall back to doing the standard name comparison.
*/
static int msdos_cmp(const struct dentry *dentry,
unsigned int len, const char *str, const struct qstr *name)
{
struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];
int error;
error = msdos_format_name(name->name, name->len, a_msdos_name, options);
if (error)
goto old_compare;
error = msdos_format_name(str, len, b_msdos_name, options);
if (error)
goto old_compare;
error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
out:
return error;
old_compare:
error = 1;
if (name->len == len)
error = memcmp(name->name, str, len);
goto out;
}
static const struct dentry_operations msdos_dentry_operations = {
.d_hash = msdos_hash,
.d_compare = msdos_cmp,
};
/*
* AV. Wrappers for FAT sb operations. Is it wise?
*/
/***** Get inode using directory and name */
static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct super_block *sb = dir->i_sb;
struct fat_slot_info sinfo;
struct inode *inode;
int err;
mutex_lock(&MSDOS_SB(sb)->s_lock);
err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
switch (err) {
case -ENOENT:
inode = NULL;
break;
case 0:
inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
brelse(sinfo.bh);
break;
default:
inode = ERR_PTR(err);
}
mutex_unlock(&MSDOS_SB(sb)->s_lock);
return d_splice_alias(inode, dentry);
}
/***** Creates a directory entry (name is already formatted). */
static int msdos_add_entry(struct inode *dir, const unsigned char *name,
int is_dir, int is_hid, int cluster,
struct timespec64 *ts, struct fat_slot_info *sinfo)
{
struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
struct msdos_dir_entry de;
__le16 time, date;
int err;
memcpy(de.name, name, MSDOS_NAME);
de.attr = is_dir ? ATTR_DIR : ATTR_ARCH;
if (is_hid)
de.attr |= ATTR_HIDDEN;
de.lcase = 0;
fat_time_unix2fat(sbi, ts, &time, &date, NULL);
de.cdate = de.adate = 0;
de.ctime = 0;
de.ctime_cs = 0;
de.time = time;
de.date = date;
fat_set_start(&de, cluster);
de.size = 0;
err = fat_add_entries(dir, &de, 1, sinfo);
if (err)
return err;
fat_truncate_time(dir, ts, S_CTIME|S_MTIME);
if (IS_DIRSYNC(dir))
(void)fat_sync_inode(dir);
else
mark_inode_dirty(dir);
return 0;
}
/***** Create a file */
static int msdos_create(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode, bool excl)
{
struct super_block *sb = dir->i_sb;
struct inode *inode = NULL;
struct fat_slot_info sinfo;
struct timespec64 ts;
unsigned char msdos_name[MSDOS_NAME];
int err, is_hid;
mutex_lock(&MSDOS_SB(sb)->s_lock);
err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
msdos_name, &MSDOS_SB(sb)->options);
if (err)
goto out;
is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
/* Have to do it due to foo vs. .foo conflicts */
if (!fat_scan(dir, msdos_name, &sinfo)) {
brelse(sinfo.bh);
err = -EINVAL;
goto out;
}
ts = current_time(dir);
err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo);
if (err)
goto out;
inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
brelse(sinfo.bh);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out;
}
fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
/* timestamp is already written, so mark_inode_dirty() is unneeded. */
d_instantiate(dentry, inode);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
if (!err)
err = fat_flush_inodes(sb, dir, inode);
return err;
}
/***** Remove a directory */
static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
{
struct super_block *sb = dir->i_sb;
struct inode *inode = d_inode(dentry);
struct fat_slot_info sinfo;
int err;
mutex_lock(&MSDOS_SB(sb)->s_lock);
err = fat_dir_empty(inode);
if (err)
goto out;
err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
if (err)
goto out;
err = fat_remove_entries(dir, &sinfo); /* and releases bh */
if (err)
goto out;
drop_nlink(dir);
clear_nlink(inode);
fat_truncate_time(inode, NULL, S_CTIME);
fat_detach(inode);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
if (!err)
err = fat_flush_inodes(sb, dir, inode);
return err;
}
/***** Make a directory */
static int msdos_mkdir(struct mnt_idmap *idmap, struct inode *dir,
struct dentry *dentry, umode_t mode)
{
struct super_block *sb = dir->i_sb;
struct fat_slot_info sinfo;
struct inode *inode;
unsigned char msdos_name[MSDOS_NAME];
struct timespec64 ts;
int err, is_hid, cluster;
mutex_lock(&MSDOS_SB(sb)->s_lock);
err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
msdos_name, &MSDOS_SB(sb)->options);
if (err)
goto out;
is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
/* foo vs .foo situation */
if (!fat_scan(dir, msdos_name, &sinfo)) {
brelse(sinfo.bh);
err = -EINVAL;
goto out;
}
ts = current_time(dir);
cluster = fat_alloc_new_dir(dir, &ts);
if (cluster < 0) {
err = cluster;
goto out;
}
err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo);
if (err)
goto out_free;
inc_nlink(dir);
inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
brelse(sinfo.bh);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
/* the directory was completed, just return a error */
goto out;
}
set_nlink(inode, 2);
fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
/* timestamp is already written, so mark_inode_dirty() is unneeded. */
d_instantiate(dentry, inode);
mutex_unlock(&MSDOS_SB(sb)->s_lock);
fat_flush_inodes(sb, dir, inode);
return 0;
out_free:
fat_free_clusters(dir, cluster);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
return err;
}
/***** Unlink a file */
static int msdos_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct super_block *sb = inode->i_sb;
struct fat_slot_info sinfo;
int err;
mutex_lock(&MSDOS_SB(sb)->s_lock);
err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
if (err)
goto out;
err = fat_remove_entries(dir, &sinfo); /* and releases bh */
if (err)
goto out;
clear_nlink(inode);
fat_truncate_time(inode, NULL, S_CTIME);
fat_detach(inode);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
if (!err)
err = fat_flush_inodes(sb, dir, inode);
return err;
}
static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
struct dentry *old_dentry,
struct inode *new_dir, unsigned char *new_name,
struct dentry *new_dentry, int is_hid)
{
struct buffer_head *dotdot_bh;
struct msdos_dir_entry *dotdot_de;
struct inode *old_inode, *new_inode;
struct fat_slot_info old_sinfo, sinfo;
struct timespec64 ts;
loff_t new_i_pos;
int err, old_attrs, is_dir, update_dotdot, corrupt = 0;
old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
old_inode = d_inode(old_dentry);
new_inode = d_inode(new_dentry);
err = fat_scan(old_dir, old_name, &old_sinfo);
if (err) {
err = -EIO;
goto out;
}
is_dir = S_ISDIR(old_inode->i_mode);
update_dotdot = (is_dir && old_dir != new_dir);
if (update_dotdot) {
if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
err = -EIO;
goto out;
}
}
old_attrs = MSDOS_I(old_inode)->i_attrs;
err = fat_scan(new_dir, new_name, &sinfo);
if (!err) {
if (!new_inode) {
/* "foo" -> ".foo" case. just change the ATTR_HIDDEN */
if (sinfo.de != old_sinfo.de) {
err = -EINVAL;
goto out;
}
if (is_hid)
MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
else
MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
if (IS_DIRSYNC(old_dir)) {
err = fat_sync_inode(old_inode);
if (err) {
MSDOS_I(old_inode)->i_attrs = old_attrs;
goto out;
}
} else
mark_inode_dirty(old_inode);
inode_inc_iversion(old_dir);
fat_truncate_time(old_dir, NULL, S_CTIME|S_MTIME);
if (IS_DIRSYNC(old_dir))
(void)fat_sync_inode(old_dir);
else
mark_inode_dirty(old_dir);
goto out;
}
}
ts = current_time(old_inode);
if (new_inode) {
if (err)
goto out;
if (is_dir) {
err = fat_dir_empty(new_inode);
if (err)
goto out;
}
new_i_pos = MSDOS_I(new_inode)->i_pos;
fat_detach(new_inode);
} else {
err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0,
&ts, &sinfo);
if (err)
goto out;
new_i_pos = sinfo.i_pos;
}
inode_inc_iversion(new_dir);
fat_detach(old_inode);
fat_attach(old_inode, new_i_pos);
if (is_hid)
MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
else
MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
if (IS_DIRSYNC(new_dir)) {
err = fat_sync_inode(old_inode);
if (err)
goto error_inode;
} else
mark_inode_dirty(old_inode);
if (update_dotdot) {
fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart);
mark_buffer_dirty_inode(dotdot_bh, old_inode);
if (IS_DIRSYNC(new_dir)) {
err = sync_dirty_buffer(dotdot_bh);
if (err)
goto error_dotdot;
}
drop_nlink(old_dir);
if (!new_inode)
inc_nlink(new_dir);
}
err = fat_remove_entries(old_dir, &old_sinfo); /* and releases bh */
old_sinfo.bh = NULL;
if (err)
goto error_dotdot;
inode_inc_iversion(old_dir);
fat_truncate_time(old_dir, &ts, S_CTIME|S_MTIME);
if (IS_DIRSYNC(old_dir))
(void)fat_sync_inode(old_dir);
else
mark_inode_dirty(old_dir);
if (new_inode) {
drop_nlink(new_inode);
if (is_dir)
drop_nlink(new_inode);
fat_truncate_time(new_inode, &ts, S_CTIME);
}
out:
brelse(sinfo.bh);
brelse(dotdot_bh);
brelse(old_sinfo.bh);
return err;
error_dotdot:
/* data cluster is shared, serious corruption */
corrupt = 1;
if (update_dotdot) {
fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart);
mark_buffer_dirty_inode(dotdot_bh, old_inode);
corrupt |= sync_dirty_buffer(dotdot_bh);
}
error_inode:
fat_detach(old_inode);
fat_attach(old_inode, old_sinfo.i_pos);
MSDOS_I(old_inode)->i_attrs = old_attrs;
if (new_inode) {
fat_attach(new_inode, new_i_pos);
if (corrupt)
corrupt |= fat_sync_inode(new_inode);
} else {
/*
* If new entry was not sharing the data cluster, it
* shouldn't be serious corruption.
*/
int err2 = fat_remove_entries(new_dir, &sinfo);
if (corrupt)
corrupt |= err2;
sinfo.bh = NULL;
}
if (corrupt < 0) {
fat_fs_error(new_dir->i_sb,
"%s: Filesystem corrupted (i_pos %lld)",
__func__, sinfo.i_pos);
}
goto out;
}
/***** Rename, a wrapper for rename_same_dir & rename_diff_dir */
static int msdos_rename(struct mnt_idmap *idmap,
struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
struct super_block *sb = old_dir->i_sb;
unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME];
int err, is_hid;
if (flags & ~RENAME_NOREPLACE)
return -EINVAL;
mutex_lock(&MSDOS_SB(sb)->s_lock);
err = msdos_format_name(old_dentry->d_name.name,
old_dentry->d_name.len, old_msdos_name,
&MSDOS_SB(old_dir->i_sb)->options);
if (err)
goto out;
err = msdos_format_name(new_dentry->d_name.name,
new_dentry->d_name.len, new_msdos_name,
&MSDOS_SB(new_dir->i_sb)->options);
if (err)
goto out;
is_hid =
(new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.');
err = do_msdos_rename(old_dir, old_msdos_name, old_dentry,
new_dir, new_msdos_name, new_dentry, is_hid);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
if (!err)
err = fat_flush_inodes(sb, old_dir, new_dir);
return err;
}
static const struct inode_operations msdos_dir_inode_operations = {
.create = msdos_create,
.lookup = msdos_lookup,
.unlink = msdos_unlink,
.mkdir = msdos_mkdir,
.rmdir = msdos_rmdir,
.rename = msdos_rename,
.setattr = fat_setattr,
.getattr = fat_getattr,
.update_time = fat_update_time,
};
static void setup(struct super_block *sb)
{
MSDOS_SB(sb)->dir_ops = &msdos_dir_inode_operations;
sb->s_d_op = &msdos_dentry_operations;
sb->s_flags |= SB_NOATIME;
}
static int msdos_fill_super(struct super_block *sb, void *data, int silent)
{
return fat_fill_super(sb, data, silent, 0, setup);
}
static struct dentry *msdos_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *data)
{
return mount_bdev(fs_type, flags, dev_name, data, msdos_fill_super);
}
static struct file_system_type msdos_fs_type = {
.owner = THIS_MODULE,
.name = "msdos",
.mount = msdos_mount,
.kill_sb = kill_block_super,
.fs_flags = FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
};
MODULE_ALIAS_FS("msdos");
static int __init init_msdos_fs(void)
{
return register_filesystem(&msdos_fs_type);
}
static void __exit exit_msdos_fs(void)
{
unregister_filesystem(&msdos_fs_type);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Werner Almesberger");
MODULE_DESCRIPTION("MS-DOS filesystem support");
module_init(init_msdos_fs)
module_exit(exit_msdos_fs)
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