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Date: Wed, 12 Nov 2014 18:41:28 +0800
From: Ming Liu <ming.liu@...driver.com>
To: Steffen Klassert <steffen.klassert@...unet.com>
CC: <herbert@...dor.apana.org.au>, <davem@...emloft.net>,
<ying.xue@...driver.com>, <linux-crypto@...r.kernel.org>,
<netdev@...r.kernel.org>
Subject: Re: [PATCH] crypto: aesni-intel - avoid IPsec re-ordering
On 11/12/2014 04:41 PM, Steffen Klassert wrote:
> On Wed, Nov 12, 2014 at 01:49:31PM +0800, Ming Liu wrote:
>> So far, the encryption/decryption are asynchronously processed in
>> softirq and cryptd which would result in a implicit order of data,
>> therefore leads IPSec stack also out of order while encapsulating
>> or decapsulating packets.
>>
>> Consider the following scenario:
>>
>> DECRYPTION INBOUND
>> |
>> |
>> +-----Packet A
>> | |
>> | |
>> | Packet B
>> | |
>> (cryptd) | | (software interrupts)
>> | ......
>> | |
>> | |
>> | Packet B(decrypted)
>> | |
>> | |
>> +---> Packet A(decrypted)
>> |
>> |
>> DECRYPTION OUTBOUND
>>
>> Add cryptd_flush_queue function fixing it by being called from softirq
>> to flush all previous queued elements before processing a new one. To
>> prevent cryptd_flush_queue() being accessed from software interrupts,
>> local_bh_disable/enable needs to be relocated in several places.
>>
>> Signed-off-by: Ming Liu <ming.liu@...driver.com>
>> ---
>> I was told that I need resend this patch with git, so here it is:
>>
>> I've figured out a new patch for this issue reported by me previously,
>> the basic idea is adding a cryptd_flush_queue function fixing it by
>> being called from softirq to flush all previous queued elements
>> before processing a new one, and it works very well so far per my test.
> I doubt that this approach can work. The cryptd encrypt/decrypt functions
> assume to be called from a workqueue worker, they can't be called from
> atomic context.
Yes, you are correct, I am on board, I need rework the patch.
>
> Can't we just use cryptd unconditionally to fix this reordering problem?
>> crypto/ablk_helper.c | 10 ++++-
>> crypto/cryptd.c | 107 ++++++++++++++++++++++++++++++++++++++++--------
>> include/crypto/cryptd.h | 13 ++++++
>> 3 files changed, 111 insertions(+), 19 deletions(-)
>>
>> diff --git a/crypto/ablk_helper.c b/crypto/ablk_helper.c
>> index ffe7278..600a70f 100644
>> --- a/crypto/ablk_helper.c
>> +++ b/crypto/ablk_helper.c
>> @@ -70,16 +70,19 @@ int ablk_encrypt(struct ablkcipher_request *req)
>> {
>> struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
>> struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
>> + struct crypto_tfm *req_tfm = crypto_ablkcipher_tfm(
>> + crypto_ablkcipher_crt(&ctx->cryptd_tfm->base)->base);
>>
>> if (!may_use_simd()) {
>> struct ablkcipher_request *cryptd_req =
>> ablkcipher_request_ctx(req);
>>
>> *cryptd_req = *req;
>> - ablkcipher_request_set_tfm(cryptd_req, &ctx->cryptd_tfm->base);
>> + cryptd_req->base.tfm = req_tfm;
>>
>> return crypto_ablkcipher_encrypt(cryptd_req);
>> } else {
>> + cryptd_flush_queue(req_tfm, CRYPTD_ENCRYPT);
> Where is CRYPTD_ENCRYPT defined?
> This does not even compile when applied to the cryptodev tree.
Sorry, it really should be CRYPTD_BLKCIPHER_ENCRYPT, I made the original
patch against 3.4 kernel, there must be something wrong when I adjusted
it to mainline kernel, sorry for that.
>
>> return __ablk_encrypt(req);
>> }
>> }
>> @@ -89,13 +92,15 @@ int ablk_decrypt(struct ablkcipher_request *req)
>> {
>> struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
>> struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
>> + struct crypto_tfm *req_tfm = crypto_ablkcipher_tfm(
>> + crypto_ablkcipher_crt(&ctx->cryptd_tfm->base)->base);
>>
>> if (!may_use_simd()) {
>> struct ablkcipher_request *cryptd_req =
>> ablkcipher_request_ctx(req);
>>
>> *cryptd_req = *req;
>> - ablkcipher_request_set_tfm(cryptd_req, &ctx->cryptd_tfm->base);
>> + cryptd_req->base.tfm = req_tfm;
>>
>> return crypto_ablkcipher_decrypt(cryptd_req);
>> } else {
>> @@ -105,6 +110,7 @@ int ablk_decrypt(struct ablkcipher_request *req)
>> desc.info = req->info;
>> desc.flags = 0;
>>
>> + cryptd_flush_queue(req_tfm, CRYPTD_DECRYPT);
> Same here.
Should be CRYPTD_BLKCIPHER_DECRYPT.
>
>> return crypto_blkcipher_crt(desc.tfm)->decrypt(
>> &desc, req->dst, req->src, req->nbytes);
>> }
>> diff --git a/crypto/cryptd.c b/crypto/cryptd.c
>> index e592c90..0b387a1 100644
>> --- a/crypto/cryptd.c
>> +++ b/crypto/cryptd.c
>> @@ -119,11 +119,13 @@ static int cryptd_enqueue_request(struct cryptd_queue *queue,
>> int cpu, err;
>> struct cryptd_cpu_queue *cpu_queue;
>>
>> + local_bh_disable();
>> cpu = get_cpu();
>> cpu_queue = this_cpu_ptr(queue->cpu_queue);
>> err = crypto_enqueue_request(&cpu_queue->queue, request);
>> queue_work_on(cpu, kcrypto_wq, &cpu_queue->work);
>> put_cpu();
>> + local_bh_enable();
>>
>> return err;
>> }
>> @@ -147,11 +149,9 @@ static void cryptd_queue_worker(struct work_struct *work)
>> preempt_disable();
>> backlog = crypto_get_backlog(&cpu_queue->queue);
>> req = crypto_dequeue_request(&cpu_queue->queue);
>> - preempt_enable();
>> - local_bh_enable();
> Everything below the local_bh_enable() should not run in atomic context
> as the subsequent functions may set the CRYPTO_TFM_REQ_MAY_SLEEP flag.
If I turn off all the CRYPTO_TFM_REQ_MAY_SLEEP in cryptd.c, is that
going to work?
>
>>
>> if (!req)
>> - return;
>> + goto out;
>>
>> if (backlog)
>> backlog->complete(backlog, -EINPROGRESS);
>> @@ -159,6 +159,9 @@ static void cryptd_queue_worker(struct work_struct *work)
>>
>> if (cpu_queue->queue.qlen)
>> queue_work(kcrypto_wq, &cpu_queue->work);
>> +out:
>> + preempt_enable();
>> + local_bh_enable();
>> }
> ...
>
>>
>> +void cryptd_flush_queue(struct crypto_tfm *tfm, cryptd_type_t type)
>> +{
>> + struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
>> + struct cryptd_instance_ctx *ictx = crypto_instance_ctx(inst);
>> + struct cryptd_queue *cryptd_queue = ictx->queue;
>> + struct cryptd_cpu_queue *cpu_queue;
>> + struct crypto_queue *queue;
>> + struct crypto_async_request *req, *tmp, *backlog;
>> + crypto_completion_t complete;
>> + int cpu;
>> + unsigned int len;
>> +
>> + switch (type) {
>> + case CRYPTD_BLKCIPHER_ENCRYPT:
>> + complete = cryptd_blkcipher_encrypt;
>> + break;
>> + case CRYPTD_BLKCIPHER_DECRYPT:
>> + complete = cryptd_blkcipher_decrypt;
>> + break;
>> + case CRYPTD_HASH_INIT:
>> + complete = cryptd_hash_init;
>> + break;
>> + case CRYPTD_HASH_UPDATE:
>> + complete = cryptd_hash_update;
>> + break;
>> + case CRYPTD_HASH_FINAL:
>> + complete = cryptd_hash_final;
>> + break;
>> + case CRYPTD_HASH_FINUP:
>> + complete = cryptd_hash_finup;
>> + break;
>> + case CRYPTD_HASH_DIGEST:
>> + complete = cryptd_hash_digest;
>> + break;
>> + case CRYPTD_AEAD_ENCRYPT:
>> + complete = cryptd_aead_encrypt;
>> + break;
>> + case CRYPTD_AEAD_DECRYPT:
>> + complete = cryptd_aead_decrypt;
>> + break;
>> + default:
>> + complete = NULL;
>> + }
>> +
>> + if (complete == NULL)
>> + return;
>> +
>> + local_bh_disable();
>> + cpu = get_cpu();
>> + cpu_queue = this_cpu_ptr(cryptd_queue->cpu_queue);
>> + queue = &cpu_queue->queue;
>> + len = queue->qlen;
>> +
>> + if (!len)
>> + goto out;
>> +
>> + list_for_each_entry_safe(req, tmp, &queue->list, list) {
>> + if (req->complete == complete) {
>> + queue->qlen--;
>> +
>> + if (queue->backlog != &queue->list) {
>> + backlog = container_of(queue->backlog,
>> + struct crypto_async_request, list);
>> + queue->backlog = queue->backlog->next;
>> + } else
>> + backlog = NULL;
>> +
>> + list_del(&req->list);
>> +
>> + if (backlog)
>> + backlog->complete(backlog, -EINPROGRESS);
>> + req->complete(req, 0);
> Same here, the complete function can not run in atomic context.
> Also, this can not ensure that the request is finalized.
> Subsequent algorithms may run asynchronously too, so this
> does not fix the reordering problem completely.
I do not know that before. Then I need rework the patch.
//Ming Liu
>
>
>
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