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Tue, 5 Mar 2024 10:16:35 +0000 (UTC) From: Eugen Hristev To: tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, jaegeuk@kernel.org, chao@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel@collabora.com, eugen.hristev@collabora.com, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, krisman@suse.de, Gabriel Krisman Bertazi Subject: [PATCH v13 4/9] ext4: Reuse generic_ci_match for ci comparisons Date: Tue, 5 Mar 2024 12:16:03 +0200 Message-Id: <20240305101608.67943-5-eugen.hristev@collabora.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240305101608.67943-1-eugen.hristev@collabora.com> References: <20240305101608.67943-1-eugen.hristev@collabora.com> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Gabriel Krisman Bertazi 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 Signed-off-by: Eugen Hristev --- fs/ext4/namei.c | 91 +++++++++++++++---------------------------------- 1 file changed, 27 insertions(+), 64 deletions(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index b96983a4c185..2d0ee232fbe7 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -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 +1451,35 @@ 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)) { + int ret; - return false; - } - } - return !ext4_ci_compare(parent, &fname->cf_name, - de->name, de->name_len, true); + /* + * 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; + + ret = generic_ci_match(parent, fname->usr_fname, + &fname->cf_name, de->name, + de->name_len); + if (ret < 0) { + /* + * 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->usr_fname, de->name, - de->name_len, false); + return ret; } #endif