Revision 9e6002c8738a9d5675ba706fcdbc0a544f814974 authored by Paulo Alcantara on 29 December 2022, 15:33:55 UTC, committed by Steve French on 04 January 2023, 06:10:19 UTC
If it failed to reconnect ipc used for getting referrals, we can just ignore it as it is not required for reconnecting the share. The worst case would be not being able to detect or chase nested links as long as dfs root server is unreachable. Before patch: $ mount.cifs //root/dfs/link /mnt -o echo_interval=10,... -> target share: /fs0/share disconnect root & fs0 $ ls /mnt ls: cannot access '/mnt': Host is down connect fs0 $ ls /mnt ls: cannot access '/mnt': Resource temporarily unavailable After patch: $ mount.cifs //root/dfs/link /mnt -o echo_interval=10,... -> target share: /fs0/share disconnect root & fs0 $ ls /mnt ls: cannot access '/mnt': Host is down connect fs0 $ ls /mnt bar.rtf dir1 foo Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de> Signed-off-by: Steve French <stfrench@microsoft.com>
1 parent 67fcb2c
xctr.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* XCTR: XOR Counter mode - Adapted from ctr.c
*
* (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
* Copyright 2021 Google LLC
*/
/*
* XCTR mode is a blockcipher mode of operation used to implement HCTR2. XCTR is
* closely related to the CTR mode of operation; the main difference is that CTR
* generates the keystream using E(CTR + IV) whereas XCTR generates the
* keystream using E(CTR ^ IV). This allows implementations to avoid dealing
* with multi-limb integers (as is required in CTR mode). XCTR is also specified
* using little-endian arithmetic which makes it slightly faster on LE machines.
*
* See the HCTR2 paper for more details:
* Length-preserving encryption with HCTR2
* (https://eprint.iacr.org/2021/1441.pdf)
*/
#include <crypto/algapi.h>
#include <crypto/internal/cipher.h>
#include <crypto/internal/skcipher.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
/* For now this implementation is limited to 16-byte blocks for simplicity */
#define XCTR_BLOCKSIZE 16
static void crypto_xctr_crypt_final(struct skcipher_walk *walk,
struct crypto_cipher *tfm, u32 byte_ctr)
{
u8 keystream[XCTR_BLOCKSIZE];
const u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
unsigned int nbytes = walk->nbytes;
__le32 ctr32 = cpu_to_le32(byte_ctr / XCTR_BLOCKSIZE + 1);
crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32));
crypto_cipher_encrypt_one(tfm, keystream, walk->iv);
crypto_xor_cpy(dst, keystream, src, nbytes);
crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32));
}
static int crypto_xctr_crypt_segment(struct skcipher_walk *walk,
struct crypto_cipher *tfm, u32 byte_ctr)
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_encrypt;
const u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
unsigned int nbytes = walk->nbytes;
__le32 ctr32 = cpu_to_le32(byte_ctr / XCTR_BLOCKSIZE + 1);
do {
crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32));
fn(crypto_cipher_tfm(tfm), dst, walk->iv);
crypto_xor(dst, src, XCTR_BLOCKSIZE);
crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32));
le32_add_cpu(&ctr32, 1);
src += XCTR_BLOCKSIZE;
dst += XCTR_BLOCKSIZE;
} while ((nbytes -= XCTR_BLOCKSIZE) >= XCTR_BLOCKSIZE);
return nbytes;
}
static int crypto_xctr_crypt_inplace(struct skcipher_walk *walk,
struct crypto_cipher *tfm, u32 byte_ctr)
{
void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
crypto_cipher_alg(tfm)->cia_encrypt;
unsigned long alignmask = crypto_cipher_alignmask(tfm);
unsigned int nbytes = walk->nbytes;
u8 *data = walk->src.virt.addr;
u8 tmp[XCTR_BLOCKSIZE + MAX_CIPHER_ALIGNMASK];
u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1);
__le32 ctr32 = cpu_to_le32(byte_ctr / XCTR_BLOCKSIZE + 1);
do {
crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32));
fn(crypto_cipher_tfm(tfm), keystream, walk->iv);
crypto_xor(data, keystream, XCTR_BLOCKSIZE);
crypto_xor(walk->iv, (u8 *)&ctr32, sizeof(ctr32));
le32_add_cpu(&ctr32, 1);
data += XCTR_BLOCKSIZE;
} while ((nbytes -= XCTR_BLOCKSIZE) >= XCTR_BLOCKSIZE);
return nbytes;
}
static int crypto_xctr_crypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
struct skcipher_walk walk;
unsigned int nbytes;
int err;
u32 byte_ctr = 0;
err = skcipher_walk_virt(&walk, req, false);
while (walk.nbytes >= XCTR_BLOCKSIZE) {
if (walk.src.virt.addr == walk.dst.virt.addr)
nbytes = crypto_xctr_crypt_inplace(&walk, cipher,
byte_ctr);
else
nbytes = crypto_xctr_crypt_segment(&walk, cipher,
byte_ctr);
byte_ctr += walk.nbytes - nbytes;
err = skcipher_walk_done(&walk, nbytes);
}
if (walk.nbytes) {
crypto_xctr_crypt_final(&walk, cipher, byte_ctr);
err = skcipher_walk_done(&walk, 0);
}
return err;
}
static int crypto_xctr_create(struct crypto_template *tmpl, struct rtattr **tb)
{
struct skcipher_instance *inst;
struct crypto_alg *alg;
int err;
inst = skcipher_alloc_instance_simple(tmpl, tb);
if (IS_ERR(inst))
return PTR_ERR(inst);
alg = skcipher_ialg_simple(inst);
/* Block size must be 16 bytes. */
err = -EINVAL;
if (alg->cra_blocksize != XCTR_BLOCKSIZE)
goto out_free_inst;
/* XCTR mode is a stream cipher. */
inst->alg.base.cra_blocksize = 1;
/*
* To simplify the implementation, configure the skcipher walk to only
* give a partial block at the very end, never earlier.
*/
inst->alg.chunksize = alg->cra_blocksize;
inst->alg.encrypt = crypto_xctr_crypt;
inst->alg.decrypt = crypto_xctr_crypt;
err = skcipher_register_instance(tmpl, inst);
if (err) {
out_free_inst:
inst->free(inst);
}
return err;
}
static struct crypto_template crypto_xctr_tmpl = {
.name = "xctr",
.create = crypto_xctr_create,
.module = THIS_MODULE,
};
static int __init crypto_xctr_module_init(void)
{
return crypto_register_template(&crypto_xctr_tmpl);
}
static void __exit crypto_xctr_module_exit(void)
{
crypto_unregister_template(&crypto_xctr_tmpl);
}
subsys_initcall(crypto_xctr_module_init);
module_exit(crypto_xctr_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("XCTR block cipher mode of operation");
MODULE_ALIAS_CRYPTO("xctr");
MODULE_IMPORT_NS(CRYPTO_INTERNAL);
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