Message-ID: <20210413222014.GS1538589@yoga>
Date:   Tue, 13 Apr 2021 17:20:14 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     herbert@...dor.apana.org.au, davem@...emloft.net,
        ebiggers@...gle.com, ardb@...nel.org, sivaprak@...eaurora.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/7] crypto: qce: common: Add support for AEAD algorithms

On Tue 13 Apr 16:31 CDT 2021, Thara Gopinath wrote:

> 
> Hi Bjorn,
> 
> On 4/5/21 6:18 PM, Bjorn Andersson wrote:
> > On Thu 25 Feb 12:27 CST 2021, Thara Gopinath wrote:
> > 
> > > Add register programming sequence for enabling AEAD
> > > algorithms on the Qualcomm crypto engine.
> > > 
> > > Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> > > ---
> > >   drivers/crypto/qce/common.c | 155 +++++++++++++++++++++++++++++++++++-
> > >   1 file changed, 153 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/crypto/qce/common.c b/drivers/crypto/qce/common.c
> > > index 05a71c5ecf61..54d209cb0525 100644
> > > --- a/drivers/crypto/qce/common.c
> > > +++ b/drivers/crypto/qce/common.c
> > > @@ -15,6 +15,16 @@
> > >   #include "core.h"
> > >   #include "regs-v5.h"
> > >   #include "sha.h"
> > > +#include "aead.h"
> > > +
> > > +static const u32 std_iv_sha1[SHA256_DIGEST_SIZE / sizeof(u32)] = {
> > > +	SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4, 0, 0, 0
> > > +};
> > > +
> > > +static const u32 std_iv_sha256[SHA256_DIGEST_SIZE / sizeof(u32)] = {
> > > +	SHA256_H0, SHA256_H1, SHA256_H2, SHA256_H3,
> > > +	SHA256_H4, SHA256_H5, SHA256_H6, SHA256_H7
> > > +};
> > >   static inline u32 qce_read(struct qce_device *qce, u32 offset)
> > >   {
> > > @@ -96,7 +106,7 @@ static inline void qce_crypto_go(struct qce_device *qce, bool result_dump)
> > >   		qce_write(qce, REG_GOPROC, BIT(GO_SHIFT));
> > >   }
> > > -#ifdef CONFIG_CRYPTO_DEV_QCE_SHA
> > > +#if defined(CONFIG_CRYPTO_DEV_QCE_SHA) || defined(CONFIG_CRYPTO_DEV_QCE_AEAD)
> > >   static u32 qce_auth_cfg(unsigned long flags, u32 key_size, u32 auth_size)
> > >   {
> > >   	u32 cfg = 0;
> > > @@ -139,7 +149,9 @@ static u32 qce_auth_cfg(unsigned long flags, u32 key_size, u32 auth_size)
> > >   	return cfg;
> > >   }
> > > +#endif
> > > +#ifdef CONFIG_CRYPTO_DEV_QCE_SHA
> > >   static int qce_setup_regs_ahash(struct crypto_async_request *async_req)
> > >   {
> > >   	struct ahash_request *req = ahash_request_cast(async_req);
> > > @@ -225,7 +237,7 @@ static int qce_setup_regs_ahash(struct crypto_async_request *async_req)
> > >   }
> > >   #endif
> > > -#ifdef CONFIG_CRYPTO_DEV_QCE_SKCIPHER
> > > +#if defined(CONFIG_CRYPTO_DEV_QCE_SKCIPHER) || defined(CONFIG_CRYPTO_DEV_QCE_AEAD)
> > >   static u32 qce_encr_cfg(unsigned long flags, u32 aes_key_size)
> > >   {
> > >   	u32 cfg = 0;
> > > @@ -271,7 +283,9 @@ static u32 qce_encr_cfg(unsigned long flags, u32 aes_key_size)
> > >   	return cfg;
> > >   }
> > > +#endif
> > > +#ifdef CONFIG_CRYPTO_DEV_QCE_SKCIPHER
> > >   static void qce_xts_swapiv(__be32 *dst, const u8 *src, unsigned int ivsize)
> > >   {
> > >   	u8 swap[QCE_AES_IV_LENGTH];
> > > @@ -386,6 +400,139 @@ static int qce_setup_regs_skcipher(struct crypto_async_request *async_req)
> > >   }
> > >   #endif
> > > +#ifdef CONFIG_CRYPTO_DEV_QCE_AEAD
> > > +static int qce_setup_regs_aead(struct crypto_async_request *async_req)
> > > +{
> > > +	struct aead_request *req = aead_request_cast(async_req);
> > > +	struct qce_aead_reqctx *rctx = aead_request_ctx(req);
> > > +	struct qce_aead_ctx *ctx = crypto_tfm_ctx(async_req->tfm);
> > > +	struct qce_alg_template *tmpl = to_aead_tmpl(crypto_aead_reqtfm(req));
> > > +	struct qce_device *qce = tmpl->qce;
> > > +	__be32 enckey[QCE_MAX_CIPHER_KEY_SIZE / sizeof(__be32)] = {0};
> > > +	__be32 enciv[QCE_MAX_IV_SIZE / sizeof(__be32)] = {0};
> > > +	__be32 authkey[QCE_SHA_HMAC_KEY_SIZE / sizeof(__be32)] = {0};
> > > +	__be32 authiv[SHA256_DIGEST_SIZE / sizeof(__be32)] = {0};
> > > +	__be32 authnonce[QCE_MAX_NONCE / sizeof(__be32)] = {0};
> > > +	unsigned int enc_keylen = ctx->enc_keylen;
> > > +	unsigned int auth_keylen = ctx->auth_keylen;
> > > +	unsigned int enc_ivsize = rctx->ivsize;
> > > +	unsigned int auth_ivsize;
> > > +	unsigned int enckey_words, enciv_words;
> > > +	unsigned int authkey_words, authiv_words, authnonce_words;
> > > +	unsigned long flags = rctx->flags;
> > > +	u32 encr_cfg = 0, auth_cfg = 0, config, totallen;
> > 
> > I don't see any reason to initialize encr_cfg or auth_cfg.
> 
> right.. I will remove it
> 
> > 
> > > +	u32 *iv_last_word;
> > > +
> > > +	qce_setup_config(qce);
> > > +
> > > +	/* Write encryption key */
> > > +	qce_cpu_to_be32p_array(enckey, ctx->enc_key, enc_keylen);
> > > +	enckey_words = enc_keylen / sizeof(u32);
> > > +	qce_write_array(qce, REG_ENCR_KEY0, (u32 *)enckey, enckey_words);
> > 
> > Afaict all "array registers" in this function are affected by the
> > CRYPTO_SETUP little endian bit, but you set this bit before launching
> > the operation dependent on IS_CCM(). So is this really working for the
> > !IS_CCM() case?
> 
> I am not sure I understand you. Below ,
> 	/* get little endianness */
> 	config = qce_config_reg(qce, 1);
> 	qce_write(qce, REG_CONFIG, config);
> 
> is outside of any checks..
> 

You're right, I misread that snippet as I was jumping through the
function. So we're unconditionally running the hardware in little endian
mode.

> > 
> > > +
> > > +	/* Write encryption iv */
> > > +	qce_cpu_to_be32p_array(enciv, rctx->iv, enc_ivsize);
> > > +	enciv_words = enc_ivsize / sizeof(u32);
> > > +	qce_write_array(qce, REG_CNTR0_IV0, (u32 *)enciv, enciv_words);
> > 
> > It would be nice if this snippet was extracted to a helper function.
> > 
> > > +
> > > +	if (IS_CCM(rctx->flags)) {
> > > +		iv_last_word = (u32 *)&enciv[enciv_words - 1];
> > > +//		qce_write(qce, REG_CNTR3_IV3, enciv[enciv_words - 1] + 1);
> > 
> > I believe this is a remnant of the two surrounding lines.
> 
> It indeed is.. I will remove it.
> 
> > 
> > > +		qce_write(qce, REG_CNTR3_IV3, (*iv_last_word) + 1);
> > 
> > enciv is an array of big endian 32-bit integers, which you tell the
> > compiler to treat as cpu-native endian, and then you do math on it.
> > Afaict from the documentation the value of REG_CNTR3_IVn should be set
> > to rctx->iv + 1, but if the hardware expects these in big endian then I
> > think you added 16777216.
> 
> So, the crypto engine documentation talks of writing to these registers in
> little endian mode. The byte stream that you get for iv from the user
> is in big endian mode as in the MSB is byte 0. So we kind of invert this and
> write  to these registers. This is what happens with declaring the __be32
> array and copying words to it from the byte stream. So now byte 0 is the LSB
> and a +1 will just add a 1 to it.
> 

But if the data come in big endian and after qce_cpu_to_be32p_array()
you're able to do math on them with expected result and you're finally
passing the data to writel() then I think that qce_cpu_to_be32p_array()
is actually be32_to_cpu() and after the conversion you should carry the
results in CPU-native u32 arrays - and thereby skip the typecasting.

> I suspect from what I read in the documentation we could get away by
> removing this and writing the big endian byte stream directly and never
> setting the little endian in config register. Though I am not sure if this
> has ever been tested out. If we change it, it will be across algorithms and
> as a separate effort.

writel() will, at least on arm64, convert the CPU native value to little
endian before writing it out, so I think the current setting make sense.

> 
> > 
> > Perhaps I'm missing something here though?
> > 
> > PS. Based on how the documentation is written, shouldn't you write out
> > REG_CNTR_IV[012] as well?
> 
> It is done on top, right ?
> qce_write_array(qce, REG_CNTR0_IV0, (u32 *)enciv, enciv_words);
> 

You're right, depending on enciv_words you write the 4 registers, then
increment the last word and write that out again.

> > 
> > > +		qce_write_array(qce, REG_ENCR_CCM_INT_CNTR0, (u32 *)enciv, enciv_words);
> > > +		qce_write(qce, REG_CNTR_MASK, ~0);
> > > +		qce_write(qce, REG_CNTR_MASK0, ~0);
> > > +		qce_write(qce, REG_CNTR_MASK1, ~0);
> > > +		qce_write(qce, REG_CNTR_MASK2, ~0);
> > > +	}
> > > +
> > > +	/* Clear authentication IV and KEY registers of previous values */
> > > +	qce_clear_array(qce, REG_AUTH_IV0, 16);
> > > +	qce_clear_array(qce, REG_AUTH_KEY0, 16);
> > > +
> > > +	/* Clear byte count */
> > > +	qce_clear_array(qce, REG_AUTH_BYTECNT0, 4);
> > > +
> > > +	/* Write authentication key */
> > > +	qce_cpu_to_be32p_array(authkey, ctx->auth_key, auth_keylen);
> > > +	authkey_words = DIV_ROUND_UP(auth_keylen, sizeof(u32));
> > > +	qce_write_array(qce, REG_AUTH_KEY0, (u32 *)authkey, authkey_words);
> > > +
> > > +	if (IS_SHA_HMAC(rctx->flags)) {
> > > +		/* Write default authentication iv */
> > > +		if (IS_SHA1_HMAC(rctx->flags)) {
> > > +			auth_ivsize = SHA1_DIGEST_SIZE;
> > > +			memcpy(authiv, std_iv_sha1, auth_ivsize);
> > > +		} else if (IS_SHA256_HMAC(rctx->flags)) {
> > > +			auth_ivsize = SHA256_DIGEST_SIZE;
> > > +			memcpy(authiv, std_iv_sha256, auth_ivsize);
> > > +		}
> > > +		authiv_words = auth_ivsize / sizeof(u32);
> > > +		qce_write_array(qce, REG_AUTH_IV0, (u32 *)authiv, authiv_words);
> > 
> > AUTH_IV0 is affected by the little endian configuration, does this imply
> > that IS_SHA_HMAC() and IS_CCM() are exclusive bits of rctx->flags? If so
> > I think it would be nice if you grouped the conditionals in a way that
> > made that obvious when reading the function.
> 
> So yes IS_SHA_HMAC() and IS_CCM() are exclusive bits of rctx->flags.
> AUTH_IVn is 0 for ccm and has initial value for HMAC algorithms. I don't
> understand the confusion here.
> 

I'm just saying that writing is as below would have made it obvious to
me that IS_SHA_HMAC() and IS_CCM() are exclusive:

if (IS_SHA_HMAC(flags)) {
  ...
} else if (IS_CCM(flags)) {
  ....
}

Regards,
Bjorn

> > 
> > > +	}
> > > +
> > > +	if (IS_CCM(rctx->flags)) {
> > > +		qce_cpu_to_be32p_array(authnonce, rctx->ccm_nonce, QCE_MAX_NONCE);
> > > +		authnonce_words = QCE_MAX_NONCE / sizeof(u32);
> > > +		qce_write_array(qce, REG_AUTH_INFO_NONCE0, (u32 *)authnonce, authnonce_words);
> > > +	}
> > > +
> > > +	/* Set up ENCR_SEG_CFG */
> > > +	encr_cfg = qce_encr_cfg(flags, enc_keylen);
> > > +	if (IS_ENCRYPT(flags))
> > > +		encr_cfg |= BIT(ENCODE_SHIFT);
> > > +	qce_write(qce, REG_ENCR_SEG_CFG, encr_cfg);
> > > +
> > > +	/* Set up AUTH_SEG_CFG */
> > > +	auth_cfg = qce_auth_cfg(rctx->flags, auth_keylen, ctx->authsize);
> > > +	auth_cfg |= BIT(AUTH_LAST_SHIFT);
> > > +	auth_cfg |= BIT(AUTH_FIRST_SHIFT);
> > > +	if (IS_ENCRYPT(flags)) {
> > > +		if (IS_CCM(rctx->flags))
> > > +			auth_cfg |= AUTH_POS_BEFORE << AUTH_POS_SHIFT;
> > > +		else
> > > +			auth_cfg |= AUTH_POS_AFTER << AUTH_POS_SHIFT;
> > > +	} else {
> > > +		if (IS_CCM(rctx->flags))
> > > +			auth_cfg |= AUTH_POS_AFTER << AUTH_POS_SHIFT;
> > > +		else
> > > +			auth_cfg |= AUTH_POS_BEFORE << AUTH_POS_SHIFT;
> > > +	}
> > > +	qce_write(qce, REG_AUTH_SEG_CFG, auth_cfg);
> > > +
> > > +	totallen = rctx->cryptlen + rctx->assoclen;
> > > +
> > > +	/* Set the encryption size and start offset */
> > > +	if (IS_CCM(rctx->flags) && IS_DECRYPT(rctx->flags))
> > > +		qce_write(qce, REG_ENCR_SEG_SIZE, rctx->cryptlen + ctx->authsize);
> > > +	else
> > > +		qce_write(qce, REG_ENCR_SEG_SIZE, rctx->cryptlen);
> > > +	qce_write(qce, REG_ENCR_SEG_START, rctx->assoclen & 0xffff);
> > > +
> > > +	/* Set the authentication size and start offset */
> > > +	qce_write(qce, REG_AUTH_SEG_SIZE, totallen);
> > > +	qce_write(qce, REG_AUTH_SEG_START, 0);
> > > +
> > > +	/* Write total length */
> > > +	if (IS_CCM(rctx->flags) && IS_DECRYPT(rctx->flags))
> > > +		qce_write(qce, REG_SEG_SIZE, totallen + ctx->authsize);
> > > +	else
> > > +		qce_write(qce, REG_SEG_SIZE, totallen);
> > > +
> > > +	/* get little endianness */
> > > +	config = qce_config_reg(qce, 1);
> > > +	qce_write(qce, REG_CONFIG, config);
> > > +
> > > +	/* Start the process */
> > > +	if (IS_CCM(flags))
> > > +		qce_crypto_go(qce, 0);
> > 
> > Second parameter is defined as "bool", please use "false" here (and true
> > below). Or
> > 
> > 	qce_crypto_go(qce, !IS_CCM(flags));
> 
> will do... I like the one liner better.
> 
> 
> -- 
> Warm Regards
> Thara

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