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ext4: optimize match for casefolded encrypted dirs

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Matching names with casefolded encrypting directories requires
decrypting entries to confirm case since we are case preserving. We can
avoid needing to decrypt if our hash values don't match.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20210319073414.1381041-3-drosen@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Daniel Rosenberg 2021-03-19 07:34:14 +00:00 committed by Theodore Ts'o
parent 471fbbea7f
commit 1ae98e295f
2 changed files with 37 additions and 33 deletions
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17
fs/ext4/ext4.h
View File

@ -2638,9 +2638,9 @@ extern unsigned ext4_free_clusters_after_init(struct super_block *sb,
ext4_fsblk_t ext4_inode_to_goal_block(struct inode *);
#ifdef CONFIG_UNICODE
extern void ext4_fname_setup_ci_filename(struct inode *dir,
extern int ext4_fname_setup_ci_filename(struct inode *dir,
const struct qstr *iname,
struct fscrypt_str *fname);
struct ext4_filename *fname);
#endif
#ifdef CONFIG_FS_ENCRYPTION
@ -2671,9 +2671,9 @@ static inline int ext4_fname_setup_filename(struct inode *dir,
ext4_fname_from_fscrypt_name(fname, &name);
#ifdef CONFIG_UNICODE
ext4_fname_setup_ci_filename(dir, iname, &fname->cf_name);
err = ext4_fname_setup_ci_filename(dir, iname, fname);
#endif
return 0;
return err;
}
static inline int ext4_fname_prepare_lookup(struct inode *dir,
@ -2690,9 +2690,9 @@ static inline int ext4_fname_prepare_lookup(struct inode *dir,
ext4_fname_from_fscrypt_name(fname, &name);
#ifdef CONFIG_UNICODE
ext4_fname_setup_ci_filename(dir, &dentry->d_name, &fname->cf_name);
err = ext4_fname_setup_ci_filename(dir, &dentry->d_name, fname);
#endif
return 0;
return err;
}
static inline void ext4_fname_free_filename(struct ext4_filename *fname)
@ -2717,15 +2717,16 @@ static inline int ext4_fname_setup_filename(struct inode *dir,
int lookup,
struct ext4_filename *fname)
{
int err = 0;
fname->usr_fname = iname;
fname->disk_name.name = (unsigned char *) iname->name;
fname->disk_name.len = iname->len;
#ifdef CONFIG_UNICODE
ext4_fname_setup_ci_filename(dir, iname, &fname->cf_name);
err = ext4_fname_setup_ci_filename(dir, iname, fname);
#endif
return 0;
return err;
}
static inline int ext4_fname_prepare_lookup(struct inode *dir,

53
fs/ext4/namei.c
View File

@ -816,7 +816,9 @@ dx_probe(struct ext4_filename *fname, struct inode *dir,
if (hinfo->hash_version <= DX_HASH_TEA)
hinfo->hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;
hinfo->seed = EXT4_SB(dir->i_sb)->s_hash_seed;
if (fname && fname_name(fname))
/* hash is already computed for encrypted casefolded directory */
if (fname && fname_name(fname) &&
!(IS_ENCRYPTED(dir) && IS_CASEFOLDED(dir)))
ext4fs_dirhash(dir, fname_name(fname), fname_len(fname), hinfo);
hash = hinfo->hash;
@ -1367,19 +1369,21 @@ out:
return ret;
}
void ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
struct fscrypt_str *cf_name)
int ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
struct ext4_filename *name)
{
struct fscrypt_str *cf_name = &name->cf_name;
struct dx_hash_info *hinfo = &name->hinfo;
int len;
if (!IS_CASEFOLDED(dir) || !dir->i_sb->s_encoding) {
cf_name->name = NULL;
return;
return 0;
}
cf_name->name = kmalloc(EXT4_NAME_LEN, GFP_NOFS);
if (!cf_name->name)
return;
return -ENOMEM;
len = utf8_casefold(dir->i_sb->s_encoding,
iname, cf_name->name,
@ -1387,10 +1391,18 @@ void ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
if (len <= 0) {
kfree(cf_name->name);
cf_name->name = NULL;
return;
}
cf_name->len = (unsigned) len;
if (!IS_ENCRYPTED(dir))
return 0;
hinfo->hash_version = DX_HASH_SIPHASH;
hinfo->seed = NULL;
if (cf_name->name)
ext4fs_dirhash(dir, cf_name->name, cf_name->len, hinfo);
else
ext4fs_dirhash(dir, iname->name, iname->len, hinfo);
return 0;
}
#endif
@ -1420,16 +1432,12 @@ static bool ext4_match(struct inode *parent,
struct qstr cf = {.name = fname->cf_name.name,
.len = fname->cf_name.len};
if (IS_ENCRYPTED(parent)) {
struct dx_hash_info hinfo;
if (fname->hinfo.hash != EXT4_DIRENT_HASH(de) ||
fname->hinfo.minor_hash !=
EXT4_DIRENT_MINOR_HASH(de)) {
hinfo.hash_version = DX_HASH_SIPHASH;
hinfo.seed = NULL;
ext4fs_dirhash(parent, fname->cf_name.name,
fname_len(fname), &hinfo);
if (hinfo.hash != EXT4_DIRENT_HASH(de) ||
hinfo.minor_hash !=
EXT4_DIRENT_MINOR_HASH(de))
return 0;
}
}
return !ext4_ci_compare(parent, &cf, de->name,
de->name_len, true);
@ -2058,15 +2066,11 @@ void ext4_insert_dentry(struct inode *dir,
de->name_len = fname_len(fname);
memcpy(de->name, fname_name(fname), fname_len(fname));
if (ext4_hash_in_dirent(dir)) {
struct dx_hash_info hinfo;
struct dx_hash_info *hinfo = &fname->hinfo;
hinfo.hash_version = DX_HASH_SIPHASH;
hinfo.seed = NULL;
ext4fs_dirhash(dir, fname_usr_name(fname),
fname_len(fname), &hinfo);
EXT4_DIRENT_HASHES(de)->hash = cpu_to_le32(hinfo.hash);
EXT4_DIRENT_HASHES(de)->hash = cpu_to_le32(hinfo->hash);
EXT4_DIRENT_HASHES(de)->minor_hash =
cpu_to_le32(hinfo.minor_hash);
cpu_to_le32(hinfo->minor_hash);
}
}
@ -2216,10 +2220,9 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
if (fname->hinfo.hash_version <= DX_HASH_TEA)
fname->hinfo.hash_version += EXT4_SB(dir->i_sb)->s_hash_unsigned;
fname->hinfo.seed = EXT4_SB(dir->i_sb)->s_hash_seed;
if (ext4_hash_in_dirent(dir))
ext4fs_dirhash(dir, fname_usr_name(fname),
fname_len(fname), &fname->hinfo);
else
/* casefolded encrypted hashes are computed on fname setup */
if (!ext4_hash_in_dirent(dir))
ext4fs_dirhash(dir, fname_name(fname),
fname_len(fname), &fname->hinfo);