linux/crypto/authenc.c

724 lines
20 KiB
C
Raw Normal View History

/*
* Authenc: Simple AEAD wrapper for IPsec
*
* 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/aead.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/authenc.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
typedef u8 *(*authenc_ahash_t)(struct aead_request *req, unsigned int flags);
struct authenc_instance_ctx {
struct crypto_ahash_spawn auth;
struct crypto_skcipher_spawn enc;
};
struct crypto_authenc_ctx {
unsigned int reqoff;
struct crypto_ahash *auth;
struct crypto_ablkcipher *enc;
};
struct authenc_request_ctx {
unsigned int cryptlen;
struct scatterlist *sg;
struct scatterlist asg[2];
struct scatterlist cipher[2];
crypto_completion_t complete;
crypto_completion_t update_complete;
char tail[];
};
static void authenc_request_complete(struct aead_request *req, int err)
{
if (err != -EINPROGRESS)
aead_request_complete(req, err);
}
int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
unsigned int keylen)
{
struct rtattr *rta = (struct rtattr *)key;
struct crypto_authenc_key_param *param;
if (!RTA_OK(rta, keylen))
return -EINVAL;
if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
return -EINVAL;
if (RTA_PAYLOAD(rta) < sizeof(*param))
return -EINVAL;
param = RTA_DATA(rta);
keys->enckeylen = be32_to_cpu(param->enckeylen);
key += RTA_ALIGN(rta->rta_len);
keylen -= RTA_ALIGN(rta->rta_len);
if (keylen < keys->enckeylen)
return -EINVAL;
keys->authkeylen = keylen - keys->enckeylen;
keys->authkey = key;
keys->enckey = key + keys->authkeylen;
return 0;
}
EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
unsigned int keylen)
{
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct crypto_ahash *auth = ctx->auth;
struct crypto_ablkcipher *enc = ctx->enc;
struct crypto_authenc_keys keys;
int err = -EINVAL;
if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
goto badkey;
crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
CRYPTO_TFM_REQ_MASK);
err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &
CRYPTO_TFM_RES_MASK);
if (err)
goto out;
crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
CRYPTO_TFM_REQ_MASK);
err = crypto_ablkcipher_setkey(enc, keys.enckey, keys.enckeylen);
crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
CRYPTO_TFM_RES_MASK);
out:
return err;
badkey:
crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
goto out;
}
static void authenc_geniv_ahash_update_done(struct crypto_async_request *areq,
int err)
{
struct aead_request *req = areq->data;
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
if (err)
goto out;
ahash_request_set_crypt(ahreq, areq_ctx->sg, ahreq->result,
areq_ctx->cryptlen);
ahash_request_set_callback(ahreq, aead_request_flags(req) &
CRYPTO_TFM_REQ_MAY_SLEEP,
areq_ctx->complete, req);
err = crypto_ahash_finup(ahreq);
if (err)
goto out;
scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
areq_ctx->cryptlen,
crypto_aead_authsize(authenc), 1);
out:
authenc_request_complete(req, err);
}
static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
{
struct aead_request *req = areq->data;
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
if (err)
goto out;
scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
areq_ctx->cryptlen,
crypto_aead_authsize(authenc), 1);
out:
aead_request_complete(req, err);
}
static void authenc_verify_ahash_update_done(struct crypto_async_request *areq,
int err)
{
u8 *ihash;
unsigned int authsize;
struct ablkcipher_request *abreq;
struct aead_request *req = areq->data;
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
unsigned int cryptlen = req->cryptlen;
if (err)
goto out;
ahash_request_set_crypt(ahreq, areq_ctx->sg, ahreq->result,
areq_ctx->cryptlen);
ahash_request_set_callback(ahreq, aead_request_flags(req) &
CRYPTO_TFM_REQ_MAY_SLEEP,
areq_ctx->complete, req);
err = crypto_ahash_finup(ahreq);
if (err)
goto out;
authsize = crypto_aead_authsize(authenc);
cryptlen -= authsize;
ihash = ahreq->result + authsize;
scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
authsize, 0);
crypto: crypto_memneq - add equality testing of memory regions w/o timing leaks When comparing MAC hashes, AEAD authentication tags, or other hash values in the context of authentication or integrity checking, it is important not to leak timing information to a potential attacker, i.e. when communication happens over a network. Bytewise memory comparisons (such as memcmp) are usually optimized so that they return a nonzero value as soon as a mismatch is found. E.g, on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch and up to ~850 cyc for a full match (cold). This early-return behavior can leak timing information as a side channel, allowing an attacker to iteratively guess the correct result. This patch adds a new method crypto_memneq ("memory not equal to each other") to the crypto API that compares memory areas of the same length in roughly "constant time" (cache misses could change the timing, but since they don't reveal information about the content of the strings being compared, they are effectively benign). Iow, best and worst case behaviour take the same amount of time to complete (in contrast to memcmp). Note that crypto_memneq (unlike memcmp) can only be used to test for equality or inequality, NOT for lexicographical order. This, however, is not an issue for its use-cases within the crypto API. We tried to locate all of the places in the crypto API where memcmp was being used for authentication or integrity checking, and convert them over to crypto_memneq. crypto_memneq is declared noinline, placed in its own source file, and compiled with optimizations that might increase code size disabled ("Os") because a smart compiler (or LTO) might notice that the return value is always compared against zero/nonzero, and might then reintroduce the same early-return optimization that we are trying to avoid. Using #pragma or __attribute__ optimization annotations of the code for disabling optimization was avoided as it seems to be considered broken or unmaintained for long time in GCC [1]. Therefore, we work around that by specifying the compile flag for memneq.o directly in the Makefile. We found that this seems to be most appropriate. As we use ("Os"), this patch also provides a loop-free "fast-path" for frequently used 16 byte digests. Similarly to kernel library string functions, leave an option for future even further optimized architecture specific assembler implementations. This was a joint work of James Yonan and Daniel Borkmann. Also thanks for feedback from Florian Weimer on this and earlier proposals [2]. [1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html [2] https://lkml.org/lkml/2013/2/10/131 Signed-off-by: James Yonan <james@openvpn.net> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2013-09-26 10:20:39 +02:00
err = crypto_memneq(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
if (err)
goto out;
abreq = aead_request_ctx(req);
ablkcipher_request_set_tfm(abreq, ctx->enc);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
req->base.complete, req->base.data);
ablkcipher_request_set_crypt(abreq, req->src, req->dst,
cryptlen, req->iv);
err = crypto_ablkcipher_decrypt(abreq);
out:
authenc_request_complete(req, err);
}
static void authenc_verify_ahash_done(struct crypto_async_request *areq,
int err)
{
u8 *ihash;
unsigned int authsize;
struct ablkcipher_request *abreq;
struct aead_request *req = areq->data;
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
unsigned int cryptlen = req->cryptlen;
if (err)
goto out;
authsize = crypto_aead_authsize(authenc);
cryptlen -= authsize;
ihash = ahreq->result + authsize;
scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
authsize, 0);
crypto: crypto_memneq - add equality testing of memory regions w/o timing leaks When comparing MAC hashes, AEAD authentication tags, or other hash values in the context of authentication or integrity checking, it is important not to leak timing information to a potential attacker, i.e. when communication happens over a network. Bytewise memory comparisons (such as memcmp) are usually optimized so that they return a nonzero value as soon as a mismatch is found. E.g, on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch and up to ~850 cyc for a full match (cold). This early-return behavior can leak timing information as a side channel, allowing an attacker to iteratively guess the correct result. This patch adds a new method crypto_memneq ("memory not equal to each other") to the crypto API that compares memory areas of the same length in roughly "constant time" (cache misses could change the timing, but since they don't reveal information about the content of the strings being compared, they are effectively benign). Iow, best and worst case behaviour take the same amount of time to complete (in contrast to memcmp). Note that crypto_memneq (unlike memcmp) can only be used to test for equality or inequality, NOT for lexicographical order. This, however, is not an issue for its use-cases within the crypto API. We tried to locate all of the places in the crypto API where memcmp was being used for authentication or integrity checking, and convert them over to crypto_memneq. crypto_memneq is declared noinline, placed in its own source file, and compiled with optimizations that might increase code size disabled ("Os") because a smart compiler (or LTO) might notice that the return value is always compared against zero/nonzero, and might then reintroduce the same early-return optimization that we are trying to avoid. Using #pragma or __attribute__ optimization annotations of the code for disabling optimization was avoided as it seems to be considered broken or unmaintained for long time in GCC [1]. Therefore, we work around that by specifying the compile flag for memneq.o directly in the Makefile. We found that this seems to be most appropriate. As we use ("Os"), this patch also provides a loop-free "fast-path" for frequently used 16 byte digests. Similarly to kernel library string functions, leave an option for future even further optimized architecture specific assembler implementations. This was a joint work of James Yonan and Daniel Borkmann. Also thanks for feedback from Florian Weimer on this and earlier proposals [2]. [1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html [2] https://lkml.org/lkml/2013/2/10/131 Signed-off-by: James Yonan <james@openvpn.net> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2013-09-26 10:20:39 +02:00
err = crypto_memneq(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
if (err)
goto out;
abreq = aead_request_ctx(req);
ablkcipher_request_set_tfm(abreq, ctx->enc);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
req->base.complete, req->base.data);
ablkcipher_request_set_crypt(abreq, req->src, req->dst,
cryptlen, req->iv);
err = crypto_ablkcipher_decrypt(abreq);
out:
authenc_request_complete(req, err);
}
static u8 *crypto_authenc_ahash_fb(struct aead_request *req, unsigned int flags)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct crypto_ahash *auth = ctx->auth;
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
u8 *hash = areq_ctx->tail;
int err;
hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
crypto_ahash_alignmask(auth) + 1);
ahash_request_set_tfm(ahreq, auth);
err = crypto_ahash_init(ahreq);
if (err)
return ERR_PTR(err);
ahash_request_set_crypt(ahreq, req->assoc, hash, req->assoclen);
ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
areq_ctx->update_complete, req);
err = crypto_ahash_update(ahreq);
if (err)
return ERR_PTR(err);
ahash_request_set_crypt(ahreq, areq_ctx->sg, hash,
areq_ctx->cryptlen);
ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
areq_ctx->complete, req);
err = crypto_ahash_finup(ahreq);
if (err)
return ERR_PTR(err);
return hash;
}
static u8 *crypto_authenc_ahash(struct aead_request *req, unsigned int flags)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct crypto_ahash *auth = ctx->auth;
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
u8 *hash = areq_ctx->tail;
int err;
hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
crypto_ahash_alignmask(auth) + 1);
ahash_request_set_tfm(ahreq, auth);
ahash_request_set_crypt(ahreq, areq_ctx->sg, hash,
areq_ctx->cryptlen);
ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
areq_ctx->complete, req);
err = crypto_ahash_digest(ahreq);
if (err)
return ERR_PTR(err);
return hash;
}
static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
unsigned int flags)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct scatterlist *dst = req->dst;
struct scatterlist *assoc = req->assoc;
struct scatterlist *cipher = areq_ctx->cipher;
struct scatterlist *asg = areq_ctx->asg;
unsigned int ivsize = crypto_aead_ivsize(authenc);
unsigned int cryptlen = req->cryptlen;
authenc_ahash_t authenc_ahash_fn = crypto_authenc_ahash_fb;
struct page *dstp;
u8 *vdst;
u8 *hash;
dstp = sg_page(dst);
vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
if (ivsize) {
sg_init_table(cipher, 2);
sg_set_buf(cipher, iv, ivsize);
scatterwalk_crypto_chain(cipher, dst, vdst == iv + ivsize, 2);
dst = cipher;
cryptlen += ivsize;
}
if (req->assoclen && sg_is_last(assoc)) {
authenc_ahash_fn = crypto_authenc_ahash;
sg_init_table(asg, 2);
sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);
scatterwalk_crypto_chain(asg, dst, 0, 2);
dst = asg;
cryptlen += req->assoclen;
}
areq_ctx->cryptlen = cryptlen;
areq_ctx->sg = dst;
areq_ctx->complete = authenc_geniv_ahash_done;
areq_ctx->update_complete = authenc_geniv_ahash_update_done;
hash = authenc_ahash_fn(req, flags);
if (IS_ERR(hash))
return PTR_ERR(hash);
scatterwalk_map_and_copy(hash, dst, cryptlen,
crypto_aead_authsize(authenc), 1);
return 0;
}
static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
int err)
{
struct aead_request *areq = req->data;
if (!err) {
struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(areq);
struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
+ ctx->reqoff);
u8 *iv = (u8 *)abreq - crypto_ablkcipher_ivsize(ctx->enc);
err = crypto_authenc_genicv(areq, iv, 0);
}
authenc_request_complete(areq, err);
}
static int crypto_authenc_encrypt(struct aead_request *req)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct crypto_ablkcipher *enc = ctx->enc;
struct scatterlist *dst = req->dst;
unsigned int cryptlen = req->cryptlen;
struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
+ ctx->reqoff);
u8 *iv = (u8 *)abreq - crypto_ablkcipher_ivsize(enc);
int err;
ablkcipher_request_set_tfm(abreq, enc);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
crypto_authenc_encrypt_done, req);
ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
memcpy(iv, req->iv, crypto_aead_ivsize(authenc));
err = crypto_ablkcipher_encrypt(abreq);
if (err)
return err;
return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
}
static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
int err)
{
struct aead_request *areq = req->data;
if (!err) {
[CRYPTO] authenc: Fix async crypto crash in crypto_authenc_genicv() crypto_authenc_givencrypt_done uses req->data as struct aead_givcrypt_request, while it really points to a struct aead_request, causing this crash: BUG: unable to handle kernel paging request at 6b6b6b6b IP: [<dc87517b>] :authenc:crypto_authenc_genicv+0x23/0x109 *pde = 00000000 Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC Modules linked in: hifn_795x authenc esp4 aead xfrm4_mode_tunnel sha1_generic hmac crypto_hash] Pid: 3074, comm: ping Not tainted (2.6.25 #4) EIP: 0060:[<dc87517b>] EFLAGS: 00010296 CPU: 0 EIP is at crypto_authenc_genicv+0x23/0x109 [authenc] EAX: daa04690 EBX: daa046e0 ECX: dab0a100 EDX: daa046b0 ESI: 6b6b6b6b EDI: dc872054 EBP: c033ff60 ESP: c033ff0c DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 Process ping (pid: 3074, ti=c033f000 task=db883a80 task.ti=dab6c000) Stack: 00000000 daa046b0 c0215a3e daa04690 dab0a100 00000000 ffffffff db9fd7f0 dba208c0 dbbb1720 00000001 daa04720 00000001 c033ff54 c0119ca9 dc852a75 c033ff60 c033ff60 daa046e0 00000000 00000001 c033ff6c dc87527b 00000001 Call Trace: [<c0215a3e>] ? dev_alloc_skb+0x14/0x29 [<c0119ca9>] ? printk+0x15/0x17 [<dc87527b>] ? crypto_authenc_givencrypt_done+0x1a/0x27 [authenc] [<dc850cca>] ? hifn_process_ready+0x34a/0x352 [hifn_795x] [<dc8353c7>] ? rhine_napipoll+0x3f2/0x3fd [via_rhine] [<dc851a56>] ? hifn_check_for_completion+0x4d/0xa6 [hifn_795x] [<dc851ab9>] ? hifn_tasklet_callback+0xa/0xc [hifn_795x] [<c011d046>] ? tasklet_action+0x3f/0x66 [<c011d230>] ? __do_softirq+0x38/0x7a [<c0105a5f>] ? do_softirq+0x3e/0x71 [<c011d17c>] ? irq_exit+0x2c/0x65 [<c010e0c0>] ? smp_apic_timer_interrupt+0x5f/0x6a [<c01042e4>] ? apic_timer_interrupt+0x28/0x30 [<dc851640>] ? hifn_handle_req+0x44a/0x50d [hifn_795x] ... Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-04-29 15:44:28 +02:00
struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
[CRYPTO] authenc: Fix async crypto crash in crypto_authenc_genicv() crypto_authenc_givencrypt_done uses req->data as struct aead_givcrypt_request, while it really points to a struct aead_request, causing this crash: BUG: unable to handle kernel paging request at 6b6b6b6b IP: [<dc87517b>] :authenc:crypto_authenc_genicv+0x23/0x109 *pde = 00000000 Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC Modules linked in: hifn_795x authenc esp4 aead xfrm4_mode_tunnel sha1_generic hmac crypto_hash] Pid: 3074, comm: ping Not tainted (2.6.25 #4) EIP: 0060:[<dc87517b>] EFLAGS: 00010296 CPU: 0 EIP is at crypto_authenc_genicv+0x23/0x109 [authenc] EAX: daa04690 EBX: daa046e0 ECX: dab0a100 EDX: daa046b0 ESI: 6b6b6b6b EDI: dc872054 EBP: c033ff60 ESP: c033ff0c DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 Process ping (pid: 3074, ti=c033f000 task=db883a80 task.ti=dab6c000) Stack: 00000000 daa046b0 c0215a3e daa04690 dab0a100 00000000 ffffffff db9fd7f0 dba208c0 dbbb1720 00000001 daa04720 00000001 c033ff54 c0119ca9 dc852a75 c033ff60 c033ff60 daa046e0 00000000 00000001 c033ff6c dc87527b 00000001 Call Trace: [<c0215a3e>] ? dev_alloc_skb+0x14/0x29 [<c0119ca9>] ? printk+0x15/0x17 [<dc87527b>] ? crypto_authenc_givencrypt_done+0x1a/0x27 [authenc] [<dc850cca>] ? hifn_process_ready+0x34a/0x352 [hifn_795x] [<dc8353c7>] ? rhine_napipoll+0x3f2/0x3fd [via_rhine] [<dc851a56>] ? hifn_check_for_completion+0x4d/0xa6 [hifn_795x] [<dc851ab9>] ? hifn_tasklet_callback+0xa/0xc [hifn_795x] [<c011d046>] ? tasklet_action+0x3f/0x66 [<c011d230>] ? __do_softirq+0x38/0x7a [<c0105a5f>] ? do_softirq+0x3e/0x71 [<c011d17c>] ? irq_exit+0x2c/0x65 [<c010e0c0>] ? smp_apic_timer_interrupt+0x5f/0x6a [<c01042e4>] ? apic_timer_interrupt+0x28/0x30 [<dc851640>] ? hifn_handle_req+0x44a/0x50d [hifn_795x] ... Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2008-04-29 15:44:28 +02:00
err = crypto_authenc_genicv(areq, greq->giv, 0);
}
authenc_request_complete(areq, err);
}
static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
{
struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct aead_request *areq = &req->areq;
struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
u8 *iv = req->giv;
int err;
skcipher_givcrypt_set_tfm(greq, ctx->enc);
skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
crypto_authenc_givencrypt_done, areq);
skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
areq->iv);
skcipher_givcrypt_set_giv(greq, iv, req->seq);
err = crypto_skcipher_givencrypt(greq);
if (err)
return err;
return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
}
static int crypto_authenc_verify(struct aead_request *req,
authenc_ahash_t authenc_ahash_fn)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
u8 *ohash;
u8 *ihash;
unsigned int authsize;
areq_ctx->complete = authenc_verify_ahash_done;
areq_ctx->update_complete = authenc_verify_ahash_update_done;
ohash = authenc_ahash_fn(req, CRYPTO_TFM_REQ_MAY_SLEEP);
if (IS_ERR(ohash))
return PTR_ERR(ohash);
authsize = crypto_aead_authsize(authenc);
ihash = ohash + authsize;
scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
authsize, 0);
crypto: crypto_memneq - add equality testing of memory regions w/o timing leaks When comparing MAC hashes, AEAD authentication tags, or other hash values in the context of authentication or integrity checking, it is important not to leak timing information to a potential attacker, i.e. when communication happens over a network. Bytewise memory comparisons (such as memcmp) are usually optimized so that they return a nonzero value as soon as a mismatch is found. E.g, on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch and up to ~850 cyc for a full match (cold). This early-return behavior can leak timing information as a side channel, allowing an attacker to iteratively guess the correct result. This patch adds a new method crypto_memneq ("memory not equal to each other") to the crypto API that compares memory areas of the same length in roughly "constant time" (cache misses could change the timing, but since they don't reveal information about the content of the strings being compared, they are effectively benign). Iow, best and worst case behaviour take the same amount of time to complete (in contrast to memcmp). Note that crypto_memneq (unlike memcmp) can only be used to test for equality or inequality, NOT for lexicographical order. This, however, is not an issue for its use-cases within the crypto API. We tried to locate all of the places in the crypto API where memcmp was being used for authentication or integrity checking, and convert them over to crypto_memneq. crypto_memneq is declared noinline, placed in its own source file, and compiled with optimizations that might increase code size disabled ("Os") because a smart compiler (or LTO) might notice that the return value is always compared against zero/nonzero, and might then reintroduce the same early-return optimization that we are trying to avoid. Using #pragma or __attribute__ optimization annotations of the code for disabling optimization was avoided as it seems to be considered broken or unmaintained for long time in GCC [1]. Therefore, we work around that by specifying the compile flag for memneq.o directly in the Makefile. We found that this seems to be most appropriate. As we use ("Os"), this patch also provides a loop-free "fast-path" for frequently used 16 byte digests. Similarly to kernel library string functions, leave an option for future even further optimized architecture specific assembler implementations. This was a joint work of James Yonan and Daniel Borkmann. Also thanks for feedback from Florian Weimer on this and earlier proposals [2]. [1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html [2] https://lkml.org/lkml/2013/2/10/131 Signed-off-by: James Yonan <james@openvpn.net> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Cc: Florian Weimer <fw@deneb.enyo.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2013-09-26 10:20:39 +02:00
return crypto_memneq(ihash, ohash, authsize) ? -EBADMSG : 0;
}
static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
unsigned int cryptlen)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
struct scatterlist *src = req->src;
struct scatterlist *assoc = req->assoc;
struct scatterlist *cipher = areq_ctx->cipher;
struct scatterlist *asg = areq_ctx->asg;
unsigned int ivsize = crypto_aead_ivsize(authenc);
authenc_ahash_t authenc_ahash_fn = crypto_authenc_ahash_fb;
struct page *srcp;
u8 *vsrc;
srcp = sg_page(src);
vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
if (ivsize) {
sg_init_table(cipher, 2);
sg_set_buf(cipher, iv, ivsize);
scatterwalk_crypto_chain(cipher, src, vsrc == iv + ivsize, 2);
src = cipher;
cryptlen += ivsize;
}
if (req->assoclen && sg_is_last(assoc)) {
authenc_ahash_fn = crypto_authenc_ahash;
sg_init_table(asg, 2);
sg_set_page(asg, sg_page(assoc), assoc->length, assoc->offset);
scatterwalk_crypto_chain(asg, src, 0, 2);
src = asg;
cryptlen += req->assoclen;
}
areq_ctx->cryptlen = cryptlen;
areq_ctx->sg = src;
return crypto_authenc_verify(req, authenc_ahash_fn);
}
static int crypto_authenc_decrypt(struct aead_request *req)
{
struct crypto_aead *authenc = crypto_aead_reqtfm(req);
struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
struct ablkcipher_request *abreq = aead_request_ctx(req);
unsigned int cryptlen = req->cryptlen;
unsigned int authsize = crypto_aead_authsize(authenc);
u8 *iv = req->iv;
int err;
if (cryptlen < authsize)
return -EINVAL;
cryptlen -= authsize;
err = crypto_authenc_iverify(req, iv, cryptlen);
if (err)
return err;
ablkcipher_request_set_tfm(abreq, ctx->enc);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
req->base.complete, req->base.data);
ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);
return crypto_ablkcipher_decrypt(abreq);
}
static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
{
struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
struct crypto_ahash *auth;
struct crypto_ablkcipher *enc;
int err;
auth = crypto_spawn_ahash(&ictx->auth);
if (IS_ERR(auth))
return PTR_ERR(auth);
enc = crypto_spawn_skcipher(&ictx->enc);
err = PTR_ERR(enc);
if (IS_ERR(enc))
goto err_free_ahash;
ctx->auth = auth;
ctx->enc = enc;
ctx->reqoff = ALIGN(2 * crypto_ahash_digestsize(auth) +
crypto_ahash_alignmask(auth),
crypto_ahash_alignmask(auth) + 1) +
crypto_ablkcipher_ivsize(enc);
tfm->crt_aead.reqsize = sizeof(struct authenc_request_ctx) +
ctx->reqoff +
max_t(unsigned int,
crypto_ahash_reqsize(auth) +
sizeof(struct ahash_request),
sizeof(struct skcipher_givcrypt_request) +
crypto_ablkcipher_reqsize(enc));
return 0;
err_free_ahash:
crypto_free_ahash(auth);
return err;
}
static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
{
struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
crypto_free_ahash(ctx->auth);
crypto_free_ablkcipher(ctx->enc);
}
static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
{
struct crypto_attr_type *algt;
struct crypto_instance *inst;
struct hash_alg_common *auth;
struct crypto_alg *auth_base;
struct crypto_alg *enc;
struct authenc_instance_ctx *ctx;
const char *enc_name;
int err;
algt = crypto_get_attr_type(tb);
if (IS_ERR(algt))
return ERR_CAST(algt);
if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
return ERR_PTR(-EINVAL);
auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
CRYPTO_ALG_TYPE_AHASH_MASK);
if (IS_ERR(auth))
return ERR_CAST(auth);
auth_base = &auth->base;
enc_name = crypto_attr_alg_name(tb[2]);
err = PTR_ERR(enc_name);
if (IS_ERR(enc_name))
goto out_put_auth;
inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
err = -ENOMEM;
if (!inst)
goto out_put_auth;
ctx = crypto_instance_ctx(inst);
err = crypto_init_ahash_spawn(&ctx->auth, auth, inst);
if (err)
goto err_free_inst;
crypto_set_skcipher_spawn(&ctx->enc, inst);
err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
crypto_requires_sync(algt->type,
algt->mask));
if (err)
goto err_drop_auth;
enc = crypto_skcipher_spawn_alg(&ctx->enc);
err = -ENAMETOOLONG;
if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
"authenc(%s,%s)", auth_base->cra_name, enc->cra_name) >=
CRYPTO_MAX_ALG_NAME)
goto err_drop_enc;
if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
"authenc(%s,%s)", auth_base->cra_driver_name,
enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
goto err_drop_enc;
inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;
inst->alg.cra_priority = enc->cra_priority *
10 + auth_base->cra_priority;
inst->alg.cra_blocksize = enc->cra_blocksize;
inst->alg.cra_alignmask = auth_base->cra_alignmask | enc->cra_alignmask;
inst->alg.cra_type = &crypto_aead_type;
inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;
inst->alg.cra_aead.maxauthsize = auth->digestsize;
inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
inst->alg.cra_init = crypto_authenc_init_tfm;
inst->alg.cra_exit = crypto_authenc_exit_tfm;
inst->alg.cra_aead.setkey = crypto_authenc_setkey;
inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;
inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;
out:
crypto_mod_put(auth_base);
return inst;
err_drop_enc:
crypto_drop_skcipher(&ctx->enc);
err_drop_auth:
crypto_drop_ahash(&ctx->auth);
err_free_inst:
kfree(inst);
out_put_auth:
inst = ERR_PTR(err);
goto out;
}
static void crypto_authenc_free(struct crypto_instance *inst)
{
struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);
crypto_drop_skcipher(&ctx->enc);
crypto_drop_ahash(&ctx->auth);
kfree(inst);
}
static struct crypto_template crypto_authenc_tmpl = {
.name = "authenc",
.alloc = crypto_authenc_alloc,
.free = crypto_authenc_free,
.module = THIS_MODULE,
};
static int __init crypto_authenc_module_init(void)
{
return crypto_register_template(&crypto_authenc_tmpl);
}
static void __exit crypto_authenc_module_exit(void)
{
crypto_unregister_template(&crypto_authenc_tmpl);
}
module_init(crypto_authenc_module_init);
module_exit(crypto_authenc_module_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");