From: Eugen Hristev <eugen.hristev@collabora.com>
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,
ebiggers@kernel.org,
Gabriel Krisman Bertazi <krisman@collabora.com>
Subject: [PATCH v16 4/9] ext4: Reuse generic_ci_match for ci comparisons
Date: Fri, 5 Apr 2024 15:13:27 +0300 [thread overview]
Message-ID: <20240405121332.689228-5-eugen.hristev@collabora.com> (raw)
In-Reply-To: <20240405121332.689228-1-eugen.hristev@collabora.com>
From: Gabriel Krisman Bertazi <krisman@collabora.com>
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>
---
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
--
2.34.1
next prev parent reply other threads:[~2024-04-05 12:14 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-05 12:13 [PATCH v16 0/9] Cache insensitive cleanup for ext4/f2fs Eugen Hristev
2024-04-05 12:13 ` [PATCH v16 1/9] ext4: Simplify the handling of cached insensitive names Eugen Hristev
2024-05-10 1:23 ` Eric Biggers
2024-04-05 12:13 ` [PATCH v16 2/9] f2fs: " Eugen Hristev
2024-05-10 1:23 ` Eric Biggers
2024-04-05 12:13 ` [PATCH v16 3/9] libfs: Introduce case-insensitive string comparison helper Eugen Hristev
2024-05-10 1:33 ` Eric Biggers
2024-05-12 21:27 ` Gabriel Krisman Bertazi
2024-05-22 14:02 ` Eugen Hristev
2024-05-22 23:05 ` Gabriel Krisman Bertazi
2024-05-26 11:49 ` Eugen Hristev
2024-05-27 20:54 ` Gabriel Krisman Bertazi
2024-04-05 12:13 ` Eugen Hristev [this message]
2024-05-10 1:23 ` [PATCH v16 4/9] ext4: Reuse generic_ci_match for ci comparisons Eric Biggers
2024-04-05 12:13 ` [PATCH v16 5/9] f2fs: " Eugen Hristev
2024-05-10 1:24 ` Eric Biggers
2024-04-05 12:13 ` [PATCH v16 6/9] ext4: Log error when lookup of encoded dentry fails Eugen Hristev
2024-05-10 1:24 ` Eric Biggers
2024-04-05 12:13 ` [PATCH v16 7/9] f2fs: " Eugen Hristev
2024-05-10 1:25 ` Eric Biggers
2024-04-05 12:13 ` [PATCH v16 8/9] ext4: Move CONFIG_UNICODE defguards into the code flow Eugen Hristev
2024-05-10 1:25 ` Eric Biggers
2024-04-05 12:13 ` [PATCH v16 9/9] f2fs: " Eugen Hristev
2024-05-10 1:25 ` Eric Biggers
2024-04-05 12:18 ` [PATCH v16 0/9] Cache insensitive cleanup for ext4/f2fs Matthew Wilcox
2024-04-05 13:02 ` Eugen Hristev
2024-04-05 16:37 ` Gabriel Krisman Bertazi
2024-05-09 15:12 ` Eugen Hristev
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