linux/fs/fat/namei_msdos.c
Linus Torvalds 8387ff2577 vfs: make the string hashes salt the hash
We always mixed in the parent pointer into the dentry name hash, but we
did it late at lookup time.  It turns out that we can simplify that
lookup-time action by salting the hash with the parent pointer early
instead of late.

A few other users of our string hashes also wanted to mix in their own
pointers into the hash, and those are updated to use the same mechanism.

Hash users that don't have any particular initial salt can just use the
NULL pointer as a no-salt.

Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-10 20:21:46 -07:00

685 lines
17 KiB
C

/*
* 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 "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 *parent, const struct dentry *dentry,
unsigned int len, const char *str, const struct qstr *name)
{
struct fat_mount_options *options = &MSDOS_SB(parent->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 timespec *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;
dir->i_ctime = dir->i_mtime = *ts;
if (IS_DIRSYNC(dir))
(void)fat_sync_inode(dir);
else
mark_inode_dirty(dir);
return 0;
}
/***** Create a file */
static int msdos_create(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 timespec 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_SEC;
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;
}
inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
/* 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);
/*
* Check whether the directory is not in use, then check
* whether it is empty.
*/
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);
inode->i_ctime = CURRENT_TIME_SEC;
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 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 timespec 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_SEC;
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);
inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
/* 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);
inode->i_ctime = CURRENT_TIME_SEC;
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 timespec 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);
old_dir->i_version++;
old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
if (IS_DIRSYNC(old_dir))
(void)fat_sync_inode(old_dir);
else
mark_inode_dirty(old_dir);
goto out;
}
}
ts = CURRENT_TIME_SEC;
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;
}
new_dir->i_version++;
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;
old_dir->i_version++;
old_dir->i_ctime = old_dir->i_mtime = ts;
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);
new_inode->i_ctime = ts;
}
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 inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
struct super_block *sb = old_dir->i_sb;
unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME];
int err, is_hid;
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,
};
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 |= MS_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,
};
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)