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case-insensitive updates for 6.9

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- Patch case-insensitive lookup by trying the case-exact comparison
 first, before falling back to costly utf8 casefolded comparison.
 
 - Fix to forbid using a case-insensitive directory as part of an
 overlayfs mount.
 
 - Patchset to ensure d_op are set at d_alloc time for fscrypt and
 casefold volumes, ensuring filesystem dentries will all have the correct
 ops, whether they come from a lookup or not.
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Merge tag 'for-next-6.9' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/krisman/unicode into vfs.misc

Merge case-insensitive updates from Gabriel Krisman Bertazi:

- Patch case-insensitive lookup by trying the case-exact comparison
  first, before falling back to costly utf8 casefolded comparison.

- Fix to forbid using a case-insensitive directory as part of an
  overlayfs mount.

- Patchset to ensure d_op are set at d_alloc time for fscrypt and
  casefold volumes, ensuring filesystem dentries will all have the
  correct ops, whether they come from a lookup or not.

* tag 'for-next-6.9' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/krisman/unicode:
  libfs: Drop generic_set_encrypted_ci_d_ops
  ubifs: Configure dentry operations at dentry-creation time
  f2fs: Configure dentry operations at dentry-creation time
  ext4: Configure dentry operations at dentry-creation time
  libfs: Add helper to choose dentry operations at mount-time
  libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops
  fscrypt: Drop d_revalidate once the key is added
  fscrypt: Drop d_revalidate for valid dentries during lookup
  fscrypt: Factor out a helper to configure the lookup dentry
  ovl: Always reject mounting over case-insensitive directories
  libfs: Attempt exact-match comparison first during casefolded lookup

Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2024-03-07 11:55:41 +01:00
commit 09406ad8e5
11 changed files with 128 additions and 86 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/crypto/hooks.c
View File

@ -102,11 +102,8 @@ int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
if (err && err != -ENOENT)
return err;
if (fname->is_nokey_name) {
spin_lock(&dentry->d_lock);
dentry->d_flags |= DCACHE_NOKEY_NAME;
spin_unlock(&dentry->d_lock);
}
fscrypt_prepare_dentry(dentry, fname->is_nokey_name);
return err;
}
EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
@ -131,12 +128,10 @@ EXPORT_SYMBOL_GPL(__fscrypt_prepare_lookup);
int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry)
{
int err = fscrypt_get_encryption_info(dir, true);
bool is_nokey_name = (!err && !fscrypt_has_encryption_key(dir));
fscrypt_prepare_dentry(dentry, is_nokey_name);
if (!err && !fscrypt_has_encryption_key(dir)) {
spin_lock(&dentry->d_lock);
dentry->d_flags |= DCACHE_NOKEY_NAME;
spin_unlock(&dentry->d_lock);
}
return err;
}
EXPORT_SYMBOL_GPL(fscrypt_prepare_lookup_partial);

1
fs/ext4/namei.c
View File

@ -1762,7 +1762,6 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir,
struct buffer_head *bh;
err = ext4_fname_prepare_lookup(dir, dentry, &fname);
generic_set_encrypted_ci_d_ops(dentry);
if (err == -ENOENT)
return NULL;
if (err)

1
fs/ext4/super.c
View File

@ -5484,6 +5484,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
goto failed_mount4;
}
generic_set_sb_d_ops(sb);
sb->s_root = d_make_root(root);
if (!sb->s_root) {
ext4_msg(sb, KERN_ERR, "get root dentry failed");

1
fs/f2fs/namei.c
View File

@ -531,7 +531,6 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
}
err = f2fs_prepare_lookup(dir, dentry, &fname);
generic_set_encrypted_ci_d_ops(dentry);
if (err == -ENOENT)
goto out_splice;
if (err)

1
fs/f2fs/super.c
View File

@ -4660,6 +4660,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
goto free_node_inode;
}
generic_set_sb_d_ops(sb);
sb->s_root = d_make_root(root); /* allocate root dentry */
if (!sb->s_root) {
err = -ENOMEM;

102
fs/libfs.c
View File

@ -1738,16 +1738,28 @@ bool is_empty_dir_inode(struct inode *inode)
static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
const char *str, const struct qstr *name)
{
const struct dentry *parent = READ_ONCE(dentry->d_parent);
const struct inode *dir = READ_ONCE(parent->d_inode);
const struct super_block *sb = dentry->d_sb;
const struct unicode_map *um = sb->s_encoding;
struct qstr qstr = QSTR_INIT(str, len);
const struct dentry *parent;
const struct inode *dir;
char strbuf[DNAME_INLINE_LEN];
int ret;
struct qstr qstr;
/*
* Attempt a case-sensitive match first. It is cheaper and
* should cover most lookups, including all the sane
* applications that expect a case-sensitive filesystem.
*
* This comparison is safe under RCU because the caller
* guarantees the consistency between str and len. See
* __d_lookup_rcu_op_compare() for details.
*/
if (len == name->len && !memcmp(str, name->name, len))
return 0;
parent = READ_ONCE(dentry->d_parent);
dir = READ_ONCE(parent->d_inode);
if (!dir || !IS_CASEFOLDED(dir))
goto fallback;
return 1;
/*
* If the dentry name is stored in-line, then it may be concurrently
* modified by a rename. If this happens, the VFS will eventually retry
@ -1758,20 +1770,14 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
if (len <= DNAME_INLINE_LEN - 1) {
memcpy(strbuf, str, len);
strbuf[len] = 0;
qstr.name = strbuf;
str = strbuf;
/* prevent compiler from optimizing out the temporary buffer */
barrier();
}
ret = utf8_strncasecmp(um, name, &qstr);
if (ret >= 0)
return ret;
qstr.len = len;
qstr.name = str;
if (sb_has_strict_encoding(sb))
return -EINVAL;
fallback:
if (len != name->len)
return 1;
return !!memcmp(str, name->name, len);
return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr);
}
/**
@ -1800,6 +1806,9 @@ static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
static const struct dentry_operations generic_ci_dentry_ops = {
.d_hash = generic_ci_d_hash,
.d_compare = generic_ci_d_compare,
#ifdef CONFIG_FS_ENCRYPTION
.d_revalidate = fscrypt_d_revalidate,
#endif
};
#endif
@ -1809,64 +1818,33 @@ static const struct dentry_operations generic_encrypted_dentry_ops = {
};
#endif
#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
.d_hash = generic_ci_d_hash,
.d_compare = generic_ci_d_compare,
.d_revalidate = fscrypt_d_revalidate,
};
#endif
/**
* generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
* @dentry: dentry to set ops on
* generic_set_sb_d_ops - helper for choosing the set of
* filesystem-wide dentry operations for the enabled features
* @sb: superblock to be configured
*
* Casefolded directories need d_hash and d_compare set, so that the dentries
* contained in them are handled case-insensitively. Note that these operations
* are needed on the parent directory rather than on the dentries in it, and
* while the casefolding flag can be toggled on and off on an empty directory,
* dentry_operations can't be changed later. As a result, if the filesystem has
* casefolding support enabled at all, we have to give all dentries the
* casefolding operations even if their inode doesn't have the casefolding flag
* currently (and thus the casefolding ops would be no-ops for now).
*
* Encryption works differently in that the only dentry operation it needs is
* d_revalidate, which it only needs on dentries that have the no-key name flag.
* The no-key flag can't be set "later", so we don't have to worry about that.
*
* Finally, to maximize compatibility with overlayfs (which isn't compatible
* with certain dentry operations) and to avoid taking an unnecessary
* performance hit, we use custom dentry_operations for each possible
* combination rather than always installing all operations.
* Filesystems supporting casefolding and/or fscrypt can call this
* helper at mount-time to configure sb->s_d_op to best set of dentry
* operations required for the enabled features. The helper must be
* called after these have been configured, but before the root dentry
* is created.
*/
void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
void generic_set_sb_d_ops(struct super_block *sb)
{
#ifdef CONFIG_FS_ENCRYPTION
bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
#endif
#if IS_ENABLED(CONFIG_UNICODE)
bool needs_ci_ops = dentry->d_sb->s_encoding;
#endif
#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
if (needs_encrypt_ops && needs_ci_ops) {
d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
if (sb->s_encoding) {
sb->s_d_op = &generic_ci_dentry_ops;
return;
}
#endif
#ifdef CONFIG_FS_ENCRYPTION
if (needs_encrypt_ops) {
d_set_d_op(dentry, &generic_encrypted_dentry_ops);
return;
}
#endif
#if IS_ENABLED(CONFIG_UNICODE)
if (needs_ci_ops) {
d_set_d_op(dentry, &generic_ci_dentry_ops);
if (sb->s_cop) {
sb->s_d_op = &generic_encrypted_dentry_ops;
return;
}
#endif
}
EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
EXPORT_SYMBOL(generic_set_sb_d_ops);
/**
* inode_maybe_inc_iversion - increments i_version

14
fs/overlayfs/params.c
View File

@ -280,12 +280,20 @@ static int ovl_mount_dir_check(struct fs_context *fc, const struct path *path,
{
struct ovl_fs_context *ctx = fc->fs_private;
if (ovl_dentry_weird(path->dentry))
return invalfc(fc, "filesystem on %s not supported", name);
if (!d_is_dir(path->dentry))
return invalfc(fc, "%s is not a directory", name);
/*
* Root dentries of case-insensitive capable filesystems might
* not have the dentry operations set, but still be incompatible
* with overlayfs. Check explicitly to prevent post-mount
* failures.
*/
if (sb_has_encoding(path->mnt->mnt_sb))
return invalfc(fc, "case-insensitive capable filesystem on %s not supported", name);
if (ovl_dentry_weird(path->dentry))
return invalfc(fc, "filesystem on %s not supported", name);
/*
* Check whether upper path is read-only here to report failures

1
fs/ubifs/dir.c
View File

@ -205,7 +205,6 @@ static struct dentry *ubifs_lookup(struct inode *dir, struct dentry *dentry,
dbg_gen("'%pd' in dir ino %lu", dentry, dir->i_ino);
err = fscrypt_prepare_lookup(dir, dentry, &nm);
generic_set_encrypted_ci_d_ops(dentry);
if (err == -ENOENT)
return d_splice_alias(NULL, dentry);
if (err)

1
fs/ubifs/super.c
View File

@ -2239,6 +2239,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
goto out_umount;
}
generic_set_sb_d_ops(sb);
sb->s_root = d_make_root(root);
if (!sb->s_root) {
err = -ENOMEM;

11
include/linux/fs.h
View File

@ -3310,7 +3310,16 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
extern int generic_check_addressable(unsigned, u64);
extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry);
extern void generic_set_sb_d_ops(struct super_block *sb);
static inline bool sb_has_encoding(const struct super_block *sb)
{
#if IS_ENABLED(CONFIG_UNICODE)
return !!sb->s_encoding;
#else
return false;
#endif
}
int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
unsigned int ia_valid);

66
include/linux/fscrypt.h
View File

@ -192,6 +192,8 @@ struct fscrypt_operations {
unsigned int *num_devs);
};
int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
static inline struct fscrypt_inode_info *
fscrypt_get_inode_info(const struct inode *inode)
{
@ -221,15 +223,29 @@ static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
}
/*
* When d_splice_alias() moves a directory's no-key alias to its plaintext alias
* as a result of the encryption key being added, DCACHE_NOKEY_NAME must be
* cleared. Note that we don't have to support arbitrary moves of this flag
* because fscrypt doesn't allow no-key names to be the source or target of a
* rename().
* When d_splice_alias() moves a directory's no-key alias to its
* plaintext alias as a result of the encryption key being added,
* DCACHE_NOKEY_NAME must be cleared and there might be an opportunity
* to disable d_revalidate. Note that we don't have to support the
* inverse operation because fscrypt doesn't allow no-key names to be
* the source or target of a rename().
*/
static inline void fscrypt_handle_d_move(struct dentry *dentry)
{
dentry->d_flags &= ~DCACHE_NOKEY_NAME;
/*
* VFS calls fscrypt_handle_d_move even for non-fscrypt
* filesystems.
*/
if (dentry->d_flags & DCACHE_NOKEY_NAME) {
dentry->d_flags &= ~DCACHE_NOKEY_NAME;
/*
* Other filesystem features might be handling dentry
* revalidation, in which case it cannot be disabled.
*/
if (dentry->d_op->d_revalidate == fscrypt_d_revalidate)
dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
}
}
/**
@ -261,6 +277,35 @@ static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
return dentry->d_flags & DCACHE_NOKEY_NAME;
}
static inline void fscrypt_prepare_dentry(struct dentry *dentry,
bool is_nokey_name)
{
/*
* This code tries to only take ->d_lock when necessary to write
* to ->d_flags. We shouldn't be peeking on d_flags for
* DCACHE_OP_REVALIDATE unlocked, but in the unlikely case
* there is a race, the worst it can happen is that we fail to
* unset DCACHE_OP_REVALIDATE and pay the cost of an extra
* d_revalidate.
*/
if (is_nokey_name) {
spin_lock(&dentry->d_lock);
dentry->d_flags |= DCACHE_NOKEY_NAME;
spin_unlock(&dentry->d_lock);
} else if (dentry->d_flags & DCACHE_OP_REVALIDATE &&
dentry->d_op->d_revalidate == fscrypt_d_revalidate) {
/*
* Unencrypted dentries and encrypted dentries where the
* key is available are always valid from fscrypt
* perspective. Avoid the cost of calling
* fscrypt_d_revalidate unnecessarily.
*/
spin_lock(&dentry->d_lock);
dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
spin_unlock(&dentry->d_lock);
}
}
/* crypto.c */
void fscrypt_enqueue_decrypt_work(struct work_struct *);
@ -368,7 +413,6 @@ int fscrypt_fname_disk_to_usr(const struct inode *inode,
bool fscrypt_match_name(const struct fscrypt_name *fname,
const u8 *de_name, u32 de_name_len);
u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);
int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
/* bio.c */
bool fscrypt_decrypt_bio(struct bio *bio);
@ -425,6 +469,11 @@ static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
return false;
}
static inline void fscrypt_prepare_dentry(struct dentry *dentry,
bool is_nokey_name)
{
}
/* crypto.c */
static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
{
@ -982,6 +1031,9 @@ static inline int fscrypt_prepare_lookup(struct inode *dir,
fname->usr_fname = &dentry->d_name;
fname->disk_name.name = (unsigned char *)dentry->d_name.name;
fname->disk_name.len = dentry->d_name.len;
fscrypt_prepare_dentry(dentry, false);
return 0;
}