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authorDaniel Rosenberg <drosen@google.com>2021-03-19 07:34:14 +0000
committerTheodore Ts'o <tytso@mit.edu>2021-04-05 22:18:36 -0400
commit1ae98e295fa2577fb5e492200c58d10230e00e99 (patch)
treec813ffd35cdd2c1451bc5999e30c04b844c9372e /fs/ext4/namei.c
parent471fbbea7ff7061b2d6474665cb5a2ceb4fd6500 (diff)
downloadandroid-dev-1ae98e295fa2577fb5e492200c58d10230e00e99.tar.gz
ext4: optimize match for casefolded encrypted dirs
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>
Diffstat (limited to 'fs/ext4/namei.c')
-rw-r--r--fs/ext4/namei.c55
1 files changed, 29 insertions, 26 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 68646500f7ba..f2e9cb71763d 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -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;
-
- 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))
+ if (fname->hinfo.hash != EXT4_DIRENT_HASH(de) ||
+ fname->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);