| Message ID | CAKv+Gu8e9sm42NKwQvQzD33JTHSaEY2q7sm0W0065dDz_rzSaA@mail.gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
On Wed, Jul 18, 2018 at 5:19 PM, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > On 18 July 2018 at 23:50, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >> On 18 July 2018 at 05:59, Arnd Bergmann <arnd@arndb.de> wrote: >>> On Sun, Jul 15, 2018 at 6:28 AM, Kees Cook <keescook@chromium.org> wrote: >>>> >>>> After my ahash to shash conversions, only ccm is left as an ahash >>>> user, since it actually uses sg. But with the hard-coded value reduced >>>> to 376, this doesn't trip the frame warnings any more. :) >>>> >>>> I'll send an updated series soon. >>> >>> Maybe we should get rid of that one as well then and remove >>> AHASH_REQUEST_ON_STACK()? >>> >>> I see that Ard (now on Cc) added this usage only recently. Looking >>> at the code some more, I also find that the descsize is probably >>> much smaller than 376 for all possible cases of "cbcmac(*)", >>> either alg->cra_blocksize plus a few bytes or sizeof(mac_desc_ctx) >>> (i.e. 20) for arch/arm64/crypto/aes-glue.c. >>> >>> Walking the sglist here means open-coding a shash_ahash_update() >>> implementation in crypto_ccm_auth(), that that doesn't seem to >>> add much complexity over what it already has to do to chain >>> the sglist today. >>> >> >> It would be better to add a variably sized ahash request member to >> struct crypto_ccm_req_priv_ctx, the only problem is that the last >> member of that struct (skreq) is variably sized already, so it would >> involve having a struct ahash_request pointer pointing into the same >> struct, after the skreq member. > > Actually, I think the below should already do the trick: ahreq and > skreq are not used at the same time, so we can stick them in a union, > and take the max() of the reqsize to ensure there's enough empty space > after it. This looks very nice indeed. > --------8<---------- > diff --git a/crypto/ccm.c b/crypto/ccm.c > index 0a083342ec8c..b242fd0d3262 100644 > --- a/crypto/ccm.c > +++ b/crypto/ccm.c > @@ -50,7 +50,10 @@ struct crypto_ccm_req_priv_ctx { > u32 flags; > struct scatterlist src[3]; > struct scatterlist dst[3]; > - struct skcipher_request skreq; > + union { > + struct ahash_request ahreq; > + struct skcipher_request skreq; > + }; > }; > And this structure is never put on the stack anywhere but always dynamically allocated anyway, right? Arnd -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On 19 July 2018 at 00:33, Arnd Bergmann <arnd@arndb.de> wrote: > On Wed, Jul 18, 2018 at 5:19 PM, Ard Biesheuvel > <ard.biesheuvel@linaro.org> wrote: >> On 18 July 2018 at 23:50, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >>> On 18 July 2018 at 05:59, Arnd Bergmann <arnd@arndb.de> wrote: >>>> On Sun, Jul 15, 2018 at 6:28 AM, Kees Cook <keescook@chromium.org> wrote: >>>>> >>>>> After my ahash to shash conversions, only ccm is left as an ahash >>>>> user, since it actually uses sg. But with the hard-coded value reduced >>>>> to 376, this doesn't trip the frame warnings any more. :) >>>>> >>>>> I'll send an updated series soon. >>>> >>>> Maybe we should get rid of that one as well then and remove >>>> AHASH_REQUEST_ON_STACK()? >>>> >>>> I see that Ard (now on Cc) added this usage only recently. Looking >>>> at the code some more, I also find that the descsize is probably >>>> much smaller than 376 for all possible cases of "cbcmac(*)", >>>> either alg->cra_blocksize plus a few bytes or sizeof(mac_desc_ctx) >>>> (i.e. 20) for arch/arm64/crypto/aes-glue.c. >>>> >>>> Walking the sglist here means open-coding a shash_ahash_update() >>>> implementation in crypto_ccm_auth(), that that doesn't seem to >>>> add much complexity over what it already has to do to chain >>>> the sglist today. >>>> >>> >>> It would be better to add a variably sized ahash request member to >>> struct crypto_ccm_req_priv_ctx, the only problem is that the last >>> member of that struct (skreq) is variably sized already, so it would >>> involve having a struct ahash_request pointer pointing into the same >>> struct, after the skreq member. >> >> Actually, I think the below should already do the trick: ahreq and >> skreq are not used at the same time, so we can stick them in a union, >> and take the max() of the reqsize to ensure there's enough empty space >> after it. > > This looks very nice indeed. > >> --------8<---------- >> diff --git a/crypto/ccm.c b/crypto/ccm.c >> index 0a083342ec8c..b242fd0d3262 100644 >> --- a/crypto/ccm.c >> +++ b/crypto/ccm.c >> @@ -50,7 +50,10 @@ struct crypto_ccm_req_priv_ctx { >> u32 flags; >> struct scatterlist src[3]; >> struct scatterlist dst[3]; >> - struct skcipher_request skreq; >> + union { >> + struct ahash_request ahreq; >> + struct skcipher_request skreq; >> + }; >> }; >> > > And this structure is never put on the stack anywhere but > always dynamically allocated anyway, right? > Yes. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Wed, Jul 18, 2018 at 8:19 AM, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > On 18 July 2018 at 23:50, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >> On 18 July 2018 at 05:59, Arnd Bergmann <arnd@arndb.de> wrote: >>> On Sun, Jul 15, 2018 at 6:28 AM, Kees Cook <keescook@chromium.org> wrote: >>>> >>>> After my ahash to shash conversions, only ccm is left as an ahash >>>> user, since it actually uses sg. But with the hard-coded value reduced >>>> to 376, this doesn't trip the frame warnings any more. :) >>>> >>>> I'll send an updated series soon. >>> >>> Maybe we should get rid of that one as well then and remove >>> AHASH_REQUEST_ON_STACK()? >>> >>> I see that Ard (now on Cc) added this usage only recently. Looking >>> at the code some more, I also find that the descsize is probably >>> much smaller than 376 for all possible cases of "cbcmac(*)", >>> either alg->cra_blocksize plus a few bytes or sizeof(mac_desc_ctx) >>> (i.e. 20) for arch/arm64/crypto/aes-glue.c. >>> >>> Walking the sglist here means open-coding a shash_ahash_update() >>> implementation in crypto_ccm_auth(), that that doesn't seem to >>> add much complexity over what it already has to do to chain >>> the sglist today. >>> >> >> It would be better to add a variably sized ahash request member to >> struct crypto_ccm_req_priv_ctx, the only problem is that the last >> member of that struct (skreq) is variably sized already, so it would >> involve having a struct ahash_request pointer pointing into the same >> struct, after the skreq member. > > Actually, I think the below should already do the trick: ahreq and > skreq are not used at the same time, so we can stick them in a union, > and take the max() of the reqsize to ensure there's enough empty space > after it. > > --------8<---------- > diff --git a/crypto/ccm.c b/crypto/ccm.c > index 0a083342ec8c..b242fd0d3262 100644 > --- a/crypto/ccm.c > +++ b/crypto/ccm.c > @@ -50,7 +50,10 @@ struct crypto_ccm_req_priv_ctx { > u32 flags; > struct scatterlist src[3]; > struct scatterlist dst[3]; > - struct skcipher_request skreq; > + union { > + struct ahash_request ahreq; > + struct skcipher_request skreq; > + }; > }; > > struct cbcmac_tfm_ctx { > @@ -181,7 +184,7 @@ > struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req); > struct crypto_aead *aead = crypto_aead_reqtfm(req); > struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead); > - AHASH_REQUEST_ON_STACK(ahreq, ctx->mac); > + struct ahash_request *ahreq = &pctx->ahreq; > unsigned int assoclen = req->assoclen; > struct scatterlist sg[3]; > u8 *odata = pctx->odata; > @@ -427,7 +430,7 @@ > crypto_aead_set_reqsize( > tfm, > align + sizeof(struct crypto_ccm_req_priv_ctx) + > - crypto_skcipher_reqsize(ctr)); > + max(crypto_ahash_reqsize(mac), crypto_skcipher_reqsize(ctr))); > > return 0; Oh, this is lovely! Thank you! Shall I add your S-o-b and add it to the series? -Kees
> On 19 Jul 2018, at 11:51, Kees Cook <keescook@chromium.org> wrote: > > On Wed, Jul 18, 2018 at 8:19 AM, Ard Biesheuvel > <ard.biesheuvel@linaro.org> wrote: >> On 18 July 2018 at 23:50, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >>>> On 18 July 2018 at 05:59, Arnd Bergmann <arnd@arndb.de> wrote: >>>>> On Sun, Jul 15, 2018 at 6:28 AM, Kees Cook <keescook@chromium.org> wrote: >>>>> >>>>> After my ahash to shash conversions, only ccm is left as an ahash >>>>> user, since it actually uses sg. But with the hard-coded value reduced >>>>> to 376, this doesn't trip the frame warnings any more. :) >>>>> >>>>> I'll send an updated series soon. >>>> >>>> Maybe we should get rid of that one as well then and remove >>>> AHASH_REQUEST_ON_STACK()? >>>> >>>> I see that Ard (now on Cc) added this usage only recently. Looking >>>> at the code some more, I also find that the descsize is probably >>>> much smaller than 376 for all possible cases of "cbcmac(*)", >>>> either alg->cra_blocksize plus a few bytes or sizeof(mac_desc_ctx) >>>> (i.e. 20) for arch/arm64/crypto/aes-glue.c. >>>> >>>> Walking the sglist here means open-coding a shash_ahash_update() >>>> implementation in crypto_ccm_auth(), that that doesn't seem to >>>> add much complexity over what it already has to do to chain >>>> the sglist today. >>>> >>> >>> It would be better to add a variably sized ahash request member to >>> struct crypto_ccm_req_priv_ctx, the only problem is that the last >>> member of that struct (skreq) is variably sized already, so it would >>> involve having a struct ahash_request pointer pointing into the same >>> struct, after the skreq member. >> >> Actually, I think the below should already do the trick: ahreq and >> skreq are not used at the same time, so we can stick them in a union, >> and take the max() of the reqsize to ensure there's enough empty space >> after it. >> >> --------8<---------- >> diff --git a/crypto/ccm.c b/crypto/ccm.c >> index 0a083342ec8c..b242fd0d3262 100644 >> --- a/crypto/ccm.c >> +++ b/crypto/ccm.c >> @@ -50,7 +50,10 @@ struct crypto_ccm_req_priv_ctx { >> u32 flags; >> struct scatterlist src[3]; >> struct scatterlist dst[3]; >> - struct skcipher_request skreq; >> + union { >> + struct ahash_request ahreq; >> + struct skcipher_request skreq; >> + }; >> }; >> >> struct cbcmac_tfm_ctx { >> @@ -181,7 +184,7 @@ >> struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req); >> struct crypto_aead *aead = crypto_aead_reqtfm(req); >> struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead); >> - AHASH_REQUEST_ON_STACK(ahreq, ctx->mac); >> + struct ahash_request *ahreq = &pctx->ahreq; >> unsigned int assoclen = req->assoclen; >> struct scatterlist sg[3]; >> u8 *odata = pctx->odata; >> @@ -427,7 +430,7 @@ >> crypto_aead_set_reqsize( >> tfm, >> align + sizeof(struct crypto_ccm_req_priv_ctx) + >> - crypto_skcipher_reqsize(ctr)); >> + max(crypto_ahash_reqsize(mac), crypto_skcipher_reqsize(ctr))); >> >> return 0; > > Oh, this is lovely! Thank you! Shall I add your S-o-b and add it to the series? > I have only build tested it, so if you make sure that it does not break anything, please go ahead. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Wed, Jul 18, 2018 at 7:55 PM, Ard Biesheuvel
<ard.biesheuvel@linaro.org> wrote:
> I have only build tested it, so if you make sure that it does not break anything, please go ahead.
I can give it a spin; what's the best way? Is CONFIG_CRYPTO_MANAGER=y
sufficient?
-Kees
> On 19 Jul 2018, at 12:09, Kees Cook <keescook@chromium.org> wrote: > > On Wed, Jul 18, 2018 at 7:55 PM, Ard Biesheuvel > <ard.biesheuvel@linaro.org> wrote: >> I have only build tested it, so if you make sure that it does not break anything, please go ahead. > > I can give it a spin; what's the best way? Is CONFIG_CRYPTO_MANAGER=y > sufficient? > You should be able to test ccm(aes) with tcrypt, yes -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On 19 July 2018 at 12:13, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > >> On 19 Jul 2018, at 12:09, Kees Cook <keescook@chromium.org> wrote: >> >> On Wed, Jul 18, 2018 at 7:55 PM, Ard Biesheuvel >> <ard.biesheuvel@linaro.org> wrote: >>> I have only build tested it, so if you make sure that it does not break anything, please go ahead. >> >> I can give it a spin; what's the best way? Is CONFIG_CRYPTO_MANAGER=y >> sufficient? >> > > You should be able to test ccm(aes) with tcrypt, yes Apologies, I should have been more clear here. I was replying on my phone while attending a meeting. The builtin test will only kick in for chaining mode templates if they are instantiated by something that invokes the algorithm, such as loading tcrypt.ko with mode=37 (assuming that ccm(aes) has to be instantiated from crypto/ccm.c and some AES cipher rather than being provided directly by, e.g., arm64's AES-CCM driver) I just did the tcrypt myself, and the patch appears to be fine. Let me know if you want me to spin the patch. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On Thu, Jul 19, 2018 at 7:54 AM, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > On 19 July 2018 at 12:13, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: >> >>> On 19 Jul 2018, at 12:09, Kees Cook <keescook@chromium.org> wrote: >>> >>> On Wed, Jul 18, 2018 at 7:55 PM, Ard Biesheuvel >>> <ard.biesheuvel@linaro.org> wrote: >>>> I have only build tested it, so if you make sure that it does not break anything, please go ahead. >>> >>> I can give it a spin; what's the best way? Is CONFIG_CRYPTO_MANAGER=y >>> sufficient? >>> >> >> You should be able to test ccm(aes) with tcrypt, yes > > Apologies, I should have been more clear here. I was replying on my > phone while attending a meeting. > > The builtin test will only kick in for chaining mode templates if they > are instantiated by something that invokes the algorithm, such as > loading tcrypt.ko with mode=37 (assuming that ccm(aes) has to be > instantiated from crypto/ccm.c and some AES cipher rather than being > provided directly by, e.g., arm64's AES-CCM driver) > > I just did the tcrypt myself, and the patch appears to be fine. Let me > know if you want me to spin the patch. Awesome, thanks for testing! I built a commit with you as the author. I'll send it out with the next batch... :) -Kees
diff --git a/crypto/ccm.c b/crypto/ccm.c index 0a083342ec8c..b242fd0d3262 100644 --- a/crypto/ccm.c +++ b/crypto/ccm.c @@ -50,7 +50,10 @@ struct crypto_ccm_req_priv_ctx { u32 flags; struct scatterlist src[3]; struct scatterlist dst[3]; - struct skcipher_request skreq; + union { + struct ahash_request ahreq; + struct skcipher_request skreq; + }; }; struct cbcmac_tfm_ctx { @@ -181,7 +184,7 @@ struct crypto_ccm_req_priv_ctx *pctx = crypto_ccm_reqctx(req); struct crypto_aead *aead = crypto_aead_reqtfm(req); struct crypto_ccm_ctx *ctx = crypto_aead_ctx(aead); - AHASH_REQUEST_ON_STACK(ahreq, ctx->mac); + struct ahash_request *ahreq = &pctx->ahreq; unsigned int assoclen = req->assoclen; struct scatterlist sg[3]; u8 *odata = pctx->odata; @@ -427,7 +430,7 @@ crypto_aead_set_reqsize( tfm, align + sizeof(struct crypto_ccm_req_priv_ctx) + - crypto_skcipher_reqsize(ctr)); + max(crypto_ahash_reqsize(mac), crypto_skcipher_reqsize(ctr))); return 0;