Commit 64e86f63 authored by Luís Henriques's avatar Luís Henriques Committed by Ilya Dryomov
Browse files

ceph: add base64 endcoding routines for encrypted names 



The base64url encoding used by fscrypt includes the '_' character, which
may cause problems in snapshot names (if the name starts with '_').
Thus, use the base64 encoding defined for IMAP mailbox names (RFC 3501),
which uses '+' and ',' instead of '-' and '_'.

Signed-off-by: default avatarLuís Henriques <lhenriques@suse.de>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarXiubo Li <xiubli@redhat.com>
Reviewed-by: default avatarMilind Changire <mchangir@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent b7b53361

fs/ceph/crypto.c

+60 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * The base64 encode/decode code was copied from fscrypt:

 * Copyright (C) 2015, Google, Inc.

 * Copyright (C) 2015, Motorola Mobility

 * Written by Uday Savagaonkar, 2014.

 * Modified by Jaegeuk Kim, 2015.

 */

#include <linux/ceph/ceph_debug.h>

#include <linux/xattr.h>

#include <linux/fscrypt.h>
@@ -7,6 +14,59 @@ 
#include "mds_client.h"

#include "crypto.h"



/*

 * The base64url encoding used by fscrypt includes the '_' character, which may

 * cause problems in snapshot names (which can not start with '_').  Thus, we

 * used the base64 encoding defined for IMAP mailbox names (RFC 3501) instead,

 * which replaces '-' and '_' by '+' and ','.

 */

static const char base64_table[65] =

	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";



int ceph_base64_encode(const u8 *src, int srclen, char *dst)

{

	u32 ac = 0;

	int bits = 0;

	int i;

	char *cp = dst;



	for (i = 0; i < srclen; i++) {

		ac = (ac << 8) | src[i];

		bits += 8;

		do {

			bits -= 6;

			*cp++ = base64_table[(ac >> bits) & 0x3f];

		} while (bits >= 6);

	}

	if (bits)

		*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];

	return cp - dst;

}



int ceph_base64_decode(const char *src, int srclen, u8 *dst)

{

	u32 ac = 0;

	int bits = 0;

	int i;

	u8 *bp = dst;



	for (i = 0; i < srclen; i++) {

		const char *p = strchr(base64_table, src[i]);



		if (p == NULL || src[i] == 0)

			return -1;

		ac = (ac << 6) | (p - base64_table);

		bits += 6;

		if (bits >= 8) {

			bits -= 8;

			*bp++ = (u8)(ac >> bits);

		}

	}

	if (ac & ((1 << bits) - 1))

		return -1;

	return bp - dst;

}



static int ceph_crypt_get_context(struct inode *inode, void *ctx, size_t len)

{

	struct ceph_inode_info *ci = ceph_inode(inode);

fs/ceph/crypto.h

+32 −0
Original line number Diff line number Diff line
@@ -27,6 +27,38 @@ static inline u32 ceph_fscrypt_auth_len(struct ceph_fscrypt_auth *fa) 
}



#ifdef CONFIG_FS_ENCRYPTION

/*

 * We want to encrypt filenames when creating them, but the encrypted

 * versions of those names may have illegal characters in them. To mitigate

 * that, we base64 encode them, but that gives us a result that can exceed

 * NAME_MAX.

 *

 * Follow a similar scheme to fscrypt itself, and cap the filename to a

 * smaller size. If the ciphertext name is longer than the value below, then

 * sha256 hash the remaining bytes.

 *

 * For the fscrypt_nokey_name struct the dirhash[2] member is useless in ceph

 * so the corresponding struct will be:

 *

 * struct fscrypt_ceph_nokey_name {

 *	u8 bytes[157];

 *	u8 sha256[SHA256_DIGEST_SIZE];

 * }; // 180 bytes => 240 bytes base64-encoded, which is <= NAME_MAX (255)

 *

 * (240 bytes is the maximum size allowed for snapshot names to take into

 *  account the format: '_<SNAPSHOT-NAME>_<INODE-NUMBER>'.)

 *

 * Note that for long names that end up having their tail portion hashed, we

 * must also store the full encrypted name (in the dentry's alternate_name

 * field).

 */

#define CEPH_NOHASH_NAME_MAX (180 - SHA256_DIGEST_SIZE)



#define CEPH_BASE64_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3)



int ceph_base64_encode(const u8 *src, int srclen, char *dst);

int ceph_base64_decode(const char *src, int srclen, u8 *dst);



void ceph_fscrypt_set_ops(struct super_block *sb);



void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc);