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ext4: Reuse generic_ci_match for ci comparisons

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Instead of reimplementing ext4_match_ci, use the new libfs helper.

It also adds a comment explaining why fname->cf_name.name must be
checked prior to the encryption hash optimization, because that tripped
me before.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com>
Link: https://lore.kernel.org/r/20240606073353.47130-5-eugen.hristev@collabora.com
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Gabriel Krisman Bertazi
2024-06-06 10:33:50 +03:00
committed by Christian Brauner
parent 6a79a4e187
commit d76b92f61f
1 changed files with 22 additions and 65 deletions
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fs/ext4/namei.c
+22 -65
View File
@@ -1390,58 +1390,6 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
}
#if IS_ENABLED(CONFIG_UNICODE)
/*
* Test whether a case-insensitive directory entry matches the filename
* being searched for. If quick is set, assume the name being looked up
* is already in the casefolded form.
*
* Returns: 0 if the directory entry matches, more than 0 if it
* doesn't match or less than zero on error.
*/
static int ext4_ci_compare(const struct inode *parent, const struct qstr *name,
u8 *de_name, size_t de_name_len, bool quick)
{
const struct super_block *sb = parent->i_sb;
const struct unicode_map *um = sb->s_encoding;
struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len);
struct qstr entry = QSTR_INIT(de_name, de_name_len);
int ret;
if (IS_ENCRYPTED(parent)) {
const struct fscrypt_str encrypted_name =
FSTR_INIT(de_name, de_name_len);
decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL);
if (!decrypted_name.name)
return -ENOMEM;
ret = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name,
&decrypted_name);
if (ret < 0)
goto out;
entry.name = decrypted_name.name;
entry.len = decrypted_name.len;
}
if (quick)
ret = utf8_strncasecmp_folded(um, name, &entry);
else
ret = utf8_strncasecmp(um, name, &entry);
if (ret < 0) {
/* Handle invalid character sequence as either an error
* or as an opaque byte sequence.
*/
if (sb_has_strict_encoding(sb))
ret = -EINVAL;
else if (name->len != entry.len)
ret = 1;
else
ret = !!memcmp(name->name, entry.name, entry.len);
}
out:
kfree(decrypted_name.name);
return ret;
}
int ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
struct ext4_filename *name)
{
@@ -1503,20 +1451,29 @@ static bool ext4_match(struct inode *parent,
#if IS_ENABLED(CONFIG_UNICODE)
if (IS_CASEFOLDED(parent) &&
(!IS_ENCRYPTED(parent) || fscrypt_has_encryption_key(parent))) {
if (fname->cf_name.name) {
if (IS_ENCRYPTED(parent)) {
if (fname->hinfo.hash != EXT4_DIRENT_HASH(de) ||
fname->hinfo.minor_hash !=
EXT4_DIRENT_MINOR_HASH(de)) {
/*
* Just checking IS_ENCRYPTED(parent) below is not
* sufficient to decide whether one can use the hash for
* skipping the string comparison, because the key might
* have been added right after
* ext4_fname_setup_ci_filename(). In this case, a hash
* mismatch will be a false negative. Therefore, make
* sure cf_name was properly initialized before
* considering the calculated hash.
*/
if (IS_ENCRYPTED(parent) && fname->cf_name.name &&
(fname->hinfo.hash != EXT4_DIRENT_HASH(de) ||
fname->hinfo.minor_hash != EXT4_DIRENT_MINOR_HASH(de)))
return false;
/*
* Treat comparison errors as not a match. The
* only case where it happens is on a disk
* corruption or ENOMEM.
*/
return false;
}
}
return !ext4_ci_compare(parent, &fname->cf_name,
de->name, de->name_len, true);
}
return !ext4_ci_compare(parent, fname->usr_fname, de->name,
de->name_len, false);
return generic_ci_match(parent, fname->usr_fname,
&fname->cf_name, de->name,
de->name_len) > 0;
}
#endif