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Commit 7f4133a5 authored by Daniel Rosenberg's avatar Daniel Rosenberg Committed by Greg Kroah-Hartman
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BACKPORT: ext4: optimize match for casefolded encrypted dirs 



[ Upstream commit 1ae98e295fa2577fb5e492200c58d10230e00e99 ]

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: default avatarDaniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20210319073414.1381041-3-drosen@google.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Change-Id: Ic74307e53dc59ec47575f33c56e291ccd137520d
parent ce3b2601

fs/ext4/ext4.h

+9 −8
Original line number Diff line number Diff line
@@ -2406,9 +2406,9 @@ 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
@@ -2439,9 +2439,9 @@ 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,
@@ -2458,9 +2458,9 @@ 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)
@@ -2485,15 +2485,16 @@ 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,

fs/ext4/namei.c

+29 −26
Original line number Diff line number Diff line
@@ -799,7 +799,9 @@ 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;
@@ -1380,19 +1382,21 @@ static int ext4_ci_compare(const struct inode *parent, const struct qstr *name, 
	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 (!needs_casefold(dir)) {

		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,
@@ -1400,10 +1404,18 @@ 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
@@ -1433,17 +1445,13 @@ 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);

		}
@@ -2070,15 +2078,11 @@ 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);

	}

}
@@ -2228,10 +2232,9 @@ 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);