linux-hardened/crypto/eseqiv.c
Herbert Xu 055906d1e7 crypto: eseqiv - Offer normal cipher functionality without RNG
The RNG may not be available during early boot, e.g., the relevant
modules may not be included in the initramfs.  As the RNG Is only
needed for IPsec, we should not let this prevent use of ciphers
without IV generators, e.g., for disk encryption.

This patch postpones the RNG allocation to the init function so
that one failure during early boot does not make the RNG unavailable
for all subsequent users of the same cipher.

More importantly, it lets the cipher live even if RNG allocation
fails.  Of course we no longer offer IV generation and which will
fail with an error if invoked.  But all other cipher capabilities
will function as usual.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-06-22 15:49:28 +08:00

242 lines
5.9 KiB
C

/*
* eseqiv: Encrypted Sequence Number IV Generator
*
* This generator generates an IV based on a sequence number by xoring it
* with a salt and then encrypting it with the same key as used to encrypt
* the plain text. This algorithm requires that the block size be equal
* to the IV size. It is mainly useful for CBC.
*
* Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <crypto/internal/skcipher.h>
#include <crypto/rng.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/spinlock.h>
#include <linux/string.h>
struct eseqiv_request_ctx {
struct scatterlist src[2];
struct scatterlist dst[2];
char tail[];
};
struct eseqiv_ctx {
spinlock_t lock;
unsigned int reqoff;
char salt[];
};
static void eseqiv_complete2(struct skcipher_givcrypt_request *req)
{
struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail,
crypto_ablkcipher_alignmask(geniv) + 1),
crypto_ablkcipher_ivsize(geniv));
}
static void eseqiv_complete(struct crypto_async_request *base, int err)
{
struct skcipher_givcrypt_request *req = base->data;
if (err)
goto out;
eseqiv_complete2(req);
out:
skcipher_givcrypt_complete(req, err);
}
static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req)
{
struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req);
struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req);
struct ablkcipher_request *subreq;
crypto_completion_t compl;
void *data;
struct scatterlist *osrc, *odst;
struct scatterlist *dst;
struct page *srcp;
struct page *dstp;
u8 *giv;
u8 *vsrc;
u8 *vdst;
__be64 seq;
unsigned int ivsize;
unsigned int len;
int err;
subreq = (void *)(reqctx->tail + ctx->reqoff);
ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv));
giv = req->giv;
compl = req->creq.base.complete;
data = req->creq.base.data;
osrc = req->creq.src;
odst = req->creq.dst;
srcp = sg_page(osrc);
dstp = sg_page(odst);
vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset;
vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset;
ivsize = crypto_ablkcipher_ivsize(geniv);
if (vsrc != giv + ivsize && vdst != giv + ivsize) {
giv = PTR_ALIGN((u8 *)reqctx->tail,
crypto_ablkcipher_alignmask(geniv) + 1);
compl = eseqiv_complete;
data = req;
}
ablkcipher_request_set_callback(subreq, req->creq.base.flags, compl,
data);
sg_init_table(reqctx->src, 2);
sg_set_buf(reqctx->src, giv, ivsize);
scatterwalk_crypto_chain(reqctx->src, osrc, vsrc == giv + ivsize, 2);
dst = reqctx->src;
if (osrc != odst) {
sg_init_table(reqctx->dst, 2);
sg_set_buf(reqctx->dst, giv, ivsize);
scatterwalk_crypto_chain(reqctx->dst, odst, vdst == giv + ivsize, 2);
dst = reqctx->dst;
}
ablkcipher_request_set_crypt(subreq, reqctx->src, dst,
req->creq.nbytes + ivsize,
req->creq.info);
memcpy(req->creq.info, ctx->salt, ivsize);
len = ivsize;
if (ivsize > sizeof(u64)) {
memset(req->giv, 0, ivsize - sizeof(u64));
len = sizeof(u64);
}
seq = cpu_to_be64(req->seq);
memcpy(req->giv + ivsize - len, &seq, len);
err = crypto_ablkcipher_encrypt(subreq);
if (err)
goto out;
if (giv != req->giv)
eseqiv_complete2(req);
out:
return err;
}
static int eseqiv_init(struct crypto_tfm *tfm)
{
struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm);
struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv);
unsigned long alignmask;
unsigned int reqsize;
int err;
spin_lock_init(&ctx->lock);
alignmask = crypto_tfm_ctx_alignment() - 1;
reqsize = sizeof(struct eseqiv_request_ctx);
if (alignmask & reqsize) {
alignmask &= reqsize;
alignmask--;
}
alignmask = ~alignmask;
alignmask &= crypto_ablkcipher_alignmask(geniv);
reqsize += alignmask;
reqsize += crypto_ablkcipher_ivsize(geniv);
reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment());
ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx);
tfm->crt_ablkcipher.reqsize = reqsize +
sizeof(struct ablkcipher_request);
err = 0;
if (!crypto_get_default_rng()) {
crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt;
err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt,
crypto_ablkcipher_ivsize(geniv));
crypto_put_default_rng();
}
return err ?: skcipher_geniv_init(tfm);
}
static struct crypto_template eseqiv_tmpl;
static struct crypto_instance *eseqiv_alloc(struct rtattr **tb)
{
struct crypto_instance *inst;
int err;
inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0);
if (IS_ERR(inst))
goto out;
err = -EINVAL;
if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize)
goto free_inst;
inst->alg.cra_init = eseqiv_init;
inst->alg.cra_exit = skcipher_geniv_exit;
inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx);
inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize;
out:
return inst;
free_inst:
skcipher_geniv_free(inst);
inst = ERR_PTR(err);
goto out;
}
static struct crypto_template eseqiv_tmpl = {
.name = "eseqiv",
.alloc = eseqiv_alloc,
.free = skcipher_geniv_free,
.module = THIS_MODULE,
};
static int __init eseqiv_module_init(void)
{
return crypto_register_template(&eseqiv_tmpl);
}
static void __exit eseqiv_module_exit(void)
{
crypto_unregister_template(&eseqiv_tmpl);
}
module_init(eseqiv_module_init);
module_exit(eseqiv_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator");
MODULE_ALIAS_CRYPTO("eseqiv");