| Message ID | 1389720829-5963-2-git-send-email-marex@denx.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tuesday, January 14, 2014 06:33:47 PM Marek Vasut wrote: > Add documentation for the pointer voodoo that is happening in crypto/ahash.c > in ahash_op_unaligned(). This code is quite confusing, so add a beefy chunk > of documentation. > > Moreover, make sure the mangled request is completely restored after finishing > this unaligned operation. This means restoring all of .result, .priv, .base.data > and .base.complete . > > Also, remove the crypto_completion_t complete = ... line present in the > ahash_op_unaligned_done() function. This type actually declares a function > pointer, which is very confusing. > > Finally, yet very important nonetheless, make sure the req->priv is free()'d > only after the original request is restored in ahash_op_unaligned_done(). > The req->priv data must not be free()'d before that in ahash_op_unaligned_finish(), > since we would be accessing previously free()'d data in ahash_op_unaligned_done() > and cause corruption. > > Signed-off-by: Marek Vasut <marex@denx.de> > Cc: David S. Miller <davem@davemloft.net> > Cc: Fabio Estevam <fabio.estevam@freescale.com> > Cc: Herbert Xu <herbert@gondor.apana.org.au> > Cc: Shawn Guo <shawn.guo@linaro.org> > Cc: Tom Lendacky <thomas.lendacky@amd.com> > --- > crypto/ahash.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 54 insertions(+), 11 deletions(-) > > diff --git a/crypto/ahash.c b/crypto/ahash.c > index a92dc38..5ca8ede 100644 > --- a/crypto/ahash.c > +++ b/crypto/ahash.c > @@ -29,6 +29,7 @@ > struct ahash_request_priv { > crypto_completion_t complete; > void *data; > + void *priv; > u8 *result; > void *ubuf[] CRYPTO_MINALIGN_ATTR; > }; > @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct ahash_request *req, int err) > if (!err) > memcpy(priv->result, req->result, > crypto_ahash_digestsize(crypto_ahash_reqtfm(req))); > - > - kzfree(priv); You can't move/remove this kzfree since a synchronous operation will not take the ahash_op_unaligned_done path. A synchronous operation will never return -EINPROGRESS and the effect will be to never free the priv structure. > } > > -static void ahash_op_unaligned_done(struct crypto_async_request *req, int err) > +static void ahash_op_unaligned_done(struct crypto_async_request *areq, int err) > { > - struct ahash_request *areq = req->data; > - struct ahash_request_priv *priv = areq->priv; > - crypto_completion_t complete = priv->complete; > - void *data = priv->data; > + struct ahash_request *req = areq->data; > + struct ahash_request_priv *priv = req->priv; > + struct crypto_async_request *data; > + > + /* > + * Restore the original request, see ahash_op_unaligned() for what > + * goes where. > + * > + * The "struct ahash_request *req" here is in fact the "req.base" > + * from the ADJUSTED request from ahash_op_unaligned(), thus as it > + * is a pointer to self, it is also the ADJUSTED "req" . > + */ > + > + /* First copy req->result into req->priv.result */ > + ahash_op_unaligned_finish(req, err); Given the above comment on the kzfree, you'll need to save all the priv values as was done previously. Thanks, Tom > > - ahash_op_unaligned_finish(areq, err); > + /* Restore the original crypto request. */ > + req->result = priv->result; > + req->base.complete = priv->complete; > + req->base.data = priv->data; > + req->priv = priv->priv; > > - areq->base.complete = complete; > - areq->base.data = data; > + /* Free the req->priv.priv from the ADJUSTED request. */ > + kzfree(priv); > > - complete(&areq->base, err); > + /* Complete the ORIGINAL request. */ > + data = req->base.data; > + req->base.complete(data, err); > } > > static int ahash_op_unaligned(struct ahash_request *req, > @@ -234,9 +250,36 @@ static int ahash_op_unaligned(struct ahash_request *req, > if (!priv) > return -ENOMEM; > > + /* > + * WARNING: Voodoo programming below! > + * > + * The code below is obscure and hard to understand, thus explanation > + * is necessary. See include/crypto/hash.h and include/linux/crypto.h > + * to understand the layout of structures used here! > + * > + * The code here will replace portions of the ORIGINAL request with > + * pointers to new code and buffers so the hashing operation can store > + * the result in aligned buffer. We will call the modified request > + * an ADJUSTED request. > + * > + * The newly mangled request will look as such: > + * > + * req { > + * .result = ADJUSTED[new aligned buffer] > + * .base.complete = ADJUSTED[pointer to completion function] > + * .base.data = ADJUSTED[*req (pointer to self)] > + * .priv = ADJUSTED[new priv] { > + * .result = ORIGINAL(result) > + * .complete = ORIGINAL(base.complete) > + * .data = ORIGINAL(base.data) > + * .priv = ORIGINAL(priv) > + * } > + */ > + > priv->result = req->result; > priv->complete = req->base.complete; > priv->data = req->base.data; > + priv->priv = req->priv; > > req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1); > req->base.complete = ahash_op_unaligned_done; > -- > 1.8.5.2 > >
On Tue, Jan 14, 2014 at 01:35:50PM -0600, Tom Lendacky wrote: > > On Tuesday, January 14, 2014 06:33:47 PM Marek Vasut wrote: > > Add documentation for the pointer voodoo that is happening in crypto/ahash.c > > in ahash_op_unaligned(). This code is quite confusing, so add a beefy chunk > > of documentation. > > > > Moreover, make sure the mangled request is completely restored after finishing > > this unaligned operation. This means restoring all of .result, .priv, .base.data > > and .base.complete . > > > > Also, remove the crypto_completion_t complete = ... line present in the > > ahash_op_unaligned_done() function. This type actually declares a function > > pointer, which is very confusing. > > > > Finally, yet very important nonetheless, make sure the req->priv is free()'d > > only after the original request is restored in ahash_op_unaligned_done(). > > The req->priv data must not be free()'d before that in ahash_op_unaligned_finish(), > > since we would be accessing previously free()'d data in ahash_op_unaligned_done() > > and cause corruption. > > > > Signed-off-by: Marek Vasut <marex@denx.de> > > Cc: David S. Miller <davem@davemloft.net> > > Cc: Fabio Estevam <fabio.estevam@freescale.com> > > Cc: Herbert Xu <herbert@gondor.apana.org.au> > > Cc: Shawn Guo <shawn.guo@linaro.org> > > Cc: Tom Lendacky <thomas.lendacky@amd.com> > > --- > > crypto/ahash.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++---------- > > 1 file changed, 54 insertions(+), 11 deletions(-) > > > > diff --git a/crypto/ahash.c b/crypto/ahash.c > > index a92dc38..5ca8ede 100644 > > --- a/crypto/ahash.c > > +++ b/crypto/ahash.c > > @@ -29,6 +29,7 @@ > > struct ahash_request_priv { > > crypto_completion_t complete; > > void *data; > > + void *priv; > > u8 *result; > > void *ubuf[] CRYPTO_MINALIGN_ATTR; > > }; > > @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct ahash_request *req, int err) > > if (!err) > > memcpy(priv->result, req->result, > > crypto_ahash_digestsize(crypto_ahash_reqtfm(req))); > > - > > - kzfree(priv); > > You can't move/remove this kzfree since a synchronous operation will not take > the ahash_op_unaligned_done path. A synchronous operation will never return > -EINPROGRESS and the effect will be to never free the priv structure. Marek, did you have a chance to address this? Thanks,
On Sunday, February 09, 2014 at 02:18:56 AM, Herbert Xu wrote: > On Tue, Jan 14, 2014 at 01:35:50PM -0600, Tom Lendacky wrote: > > On Tuesday, January 14, 2014 06:33:47 PM Marek Vasut wrote: > > > Add documentation for the pointer voodoo that is happening in > > > crypto/ahash.c in ahash_op_unaligned(). This code is quite confusing, > > > so add a beefy chunk of documentation. > > > > > > Moreover, make sure the mangled request is completely restored after > > > finishing this unaligned operation. This means restoring all of > > > .result, .priv, .base.data and .base.complete . > > > > > > Also, remove the crypto_completion_t complete = ... line present in the > > > ahash_op_unaligned_done() function. This type actually declares a > > > function pointer, which is very confusing. > > > > > > Finally, yet very important nonetheless, make sure the req->priv is > > > free()'d only after the original request is restored in > > > ahash_op_unaligned_done(). The req->priv data must not be free()'d > > > before that in ahash_op_unaligned_finish(), since we would be > > > accessing previously free()'d data in ahash_op_unaligned_done() and > > > cause corruption. > > > > > > Signed-off-by: Marek Vasut <marex@denx.de> > > > Cc: David S. Miller <davem@davemloft.net> > > > Cc: Fabio Estevam <fabio.estevam@freescale.com> > > > Cc: Herbert Xu <herbert@gondor.apana.org.au> > > > Cc: Shawn Guo <shawn.guo@linaro.org> > > > Cc: Tom Lendacky <thomas.lendacky@amd.com> > > > --- > > > > > > crypto/ahash.c | 65 > > > ++++++++++++++++++++++++++++++++++++++++++++++++---------- 1 file > > > changed, 54 insertions(+), 11 deletions(-) > > > > > > diff --git a/crypto/ahash.c b/crypto/ahash.c > > > index a92dc38..5ca8ede 100644 > > > --- a/crypto/ahash.c > > > +++ b/crypto/ahash.c > > > @@ -29,6 +29,7 @@ > > > > > > struct ahash_request_priv { > > > > > > crypto_completion_t complete; > > > void *data; > > > > > > + void *priv; > > > > > > u8 *result; > > > void *ubuf[] CRYPTO_MINALIGN_ATTR; > > > > > > }; > > > > > > @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct > > > ahash_request *req, int err) > > > > > > if (!err) > > > > > > memcpy(priv->result, req->result, > > > > > > crypto_ahash_digestsize(crypto_ahash_reqtfm(req))); > > > > > > - > > > - kzfree(priv); > > > > You can't move/remove this kzfree since a synchronous operation will not > > take the ahash_op_unaligned_done path. A synchronous operation will > > never return -EINPROGRESS and the effect will be to never free the priv > > structure. > > Marek, did you have a chance to address this? Hi, it's in the pipeline, I'm just overloaded. We missed a MW for this, right ? :-(
On Sunday, February 09, 2014 at 02:18:56 AM, Herbert Xu wrote: > On Tue, Jan 14, 2014 at 01:35:50PM -0600, Tom Lendacky wrote: > > On Tuesday, January 14, 2014 06:33:47 PM Marek Vasut wrote: > > > Add documentation for the pointer voodoo that is happening in > > > crypto/ahash.c in ahash_op_unaligned(). This code is quite confusing, > > > so add a beefy chunk of documentation. > > > > > > Moreover, make sure the mangled request is completely restored after > > > finishing this unaligned operation. This means restoring all of > > > .result, .priv, .base.data and .base.complete . > > > > > > Also, remove the crypto_completion_t complete = ... line present in the > > > ahash_op_unaligned_done() function. This type actually declares a > > > function pointer, which is very confusing. > > > > > > Finally, yet very important nonetheless, make sure the req->priv is > > > free()'d only after the original request is restored in > > > ahash_op_unaligned_done(). The req->priv data must not be free()'d > > > before that in ahash_op_unaligned_finish(), since we would be > > > accessing previously free()'d data in ahash_op_unaligned_done() and > > > cause corruption. > > > > > > Signed-off-by: Marek Vasut <marex@denx.de> > > > Cc: David S. Miller <davem@davemloft.net> > > > Cc: Fabio Estevam <fabio.estevam@freescale.com> > > > Cc: Herbert Xu <herbert@gondor.apana.org.au> > > > Cc: Shawn Guo <shawn.guo@linaro.org> > > > Cc: Tom Lendacky <thomas.lendacky@amd.com> > > > --- > > > > > > crypto/ahash.c | 65 > > > ++++++++++++++++++++++++++++++++++++++++++++++++---------- 1 file > > > changed, 54 insertions(+), 11 deletions(-) > > > > > > diff --git a/crypto/ahash.c b/crypto/ahash.c > > > index a92dc38..5ca8ede 100644 > > > --- a/crypto/ahash.c > > > +++ b/crypto/ahash.c > > > @@ -29,6 +29,7 @@ > > > > > > struct ahash_request_priv { > > > > > > crypto_completion_t complete; > > > void *data; > > > > > > + void *priv; > > > > > > u8 *result; > > > void *ubuf[] CRYPTO_MINALIGN_ATTR; > > > > > > }; > > > > > > @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct > > > ahash_request *req, int err) > > > > > > if (!err) > > > > > > memcpy(priv->result, req->result, > > > > > > crypto_ahash_digestsize(crypto_ahash_reqtfm(req))); > > > > > > - > > > - kzfree(priv); > > > > You can't move/remove this kzfree since a synchronous operation will not > > take the ahash_op_unaligned_done path. A synchronous operation will > > never return -EINPROGRESS and the effect will be to never free the priv > > structure. > > Marek, did you have a chance to address this? V2 is on it's way. I know there's really no apology for this horrible delay :-(
diff --git a/crypto/ahash.c b/crypto/ahash.c index a92dc38..5ca8ede 100644 --- a/crypto/ahash.c +++ b/crypto/ahash.c @@ -29,6 +29,7 @@ struct ahash_request_priv { crypto_completion_t complete; void *data; + void *priv; u8 *result; void *ubuf[] CRYPTO_MINALIGN_ATTR; }; @@ -200,23 +201,38 @@ static void ahash_op_unaligned_finish(struct ahash_request *req, int err) if (!err) memcpy(priv->result, req->result, crypto_ahash_digestsize(crypto_ahash_reqtfm(req))); - - kzfree(priv); } -static void ahash_op_unaligned_done(struct crypto_async_request *req, int err) +static void ahash_op_unaligned_done(struct crypto_async_request *areq, int err) { - struct ahash_request *areq = req->data; - struct ahash_request_priv *priv = areq->priv; - crypto_completion_t complete = priv->complete; - void *data = priv->data; + struct ahash_request *req = areq->data; + struct ahash_request_priv *priv = req->priv; + struct crypto_async_request *data; + + /* + * Restore the original request, see ahash_op_unaligned() for what + * goes where. + * + * The "struct ahash_request *req" here is in fact the "req.base" + * from the ADJUSTED request from ahash_op_unaligned(), thus as it + * is a pointer to self, it is also the ADJUSTED "req" . + */ + + /* First copy req->result into req->priv.result */ + ahash_op_unaligned_finish(req, err); - ahash_op_unaligned_finish(areq, err); + /* Restore the original crypto request. */ + req->result = priv->result; + req->base.complete = priv->complete; + req->base.data = priv->data; + req->priv = priv->priv; - areq->base.complete = complete; - areq->base.data = data; + /* Free the req->priv.priv from the ADJUSTED request. */ + kzfree(priv); - complete(&areq->base, err); + /* Complete the ORIGINAL request. */ + data = req->base.data; + req->base.complete(data, err); } static int ahash_op_unaligned(struct ahash_request *req, @@ -234,9 +250,36 @@ static int ahash_op_unaligned(struct ahash_request *req, if (!priv) return -ENOMEM; + /* + * WARNING: Voodoo programming below! + * + * The code below is obscure and hard to understand, thus explanation + * is necessary. See include/crypto/hash.h and include/linux/crypto.h + * to understand the layout of structures used here! + * + * The code here will replace portions of the ORIGINAL request with + * pointers to new code and buffers so the hashing operation can store + * the result in aligned buffer. We will call the modified request + * an ADJUSTED request. + * + * The newly mangled request will look as such: + * + * req { + * .result = ADJUSTED[new aligned buffer] + * .base.complete = ADJUSTED[pointer to completion function] + * .base.data = ADJUSTED[*req (pointer to self)] + * .priv = ADJUSTED[new priv] { + * .result = ORIGINAL(result) + * .complete = ORIGINAL(base.complete) + * .data = ORIGINAL(base.data) + * .priv = ORIGINAL(priv) + * } + */ + priv->result = req->result; priv->complete = req->base.complete; priv->data = req->base.data; + priv->priv = req->priv; req->result = PTR_ALIGN((u8 *)priv->ubuf, alignmask + 1); req->base.complete = ahash_op_unaligned_done;
Add documentation for the pointer voodoo that is happening in crypto/ahash.c in ahash_op_unaligned(). This code is quite confusing, so add a beefy chunk of documentation. Moreover, make sure the mangled request is completely restored after finishing this unaligned operation. This means restoring all of .result, .priv, .base.data and .base.complete . Also, remove the crypto_completion_t complete = ... line present in the ahash_op_unaligned_done() function. This type actually declares a function pointer, which is very confusing. Finally, yet very important nonetheless, make sure the req->priv is free()'d only after the original request is restored in ahash_op_unaligned_done(). The req->priv data must not be free()'d before that in ahash_op_unaligned_finish(), since we would be accessing previously free()'d data in ahash_op_unaligned_done() and cause corruption. Signed-off-by: Marek Vasut <marex@denx.de> Cc: David S. Miller <davem@davemloft.net> Cc: Fabio Estevam <fabio.estevam@freescale.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Shawn Guo <shawn.guo@linaro.org> Cc: Tom Lendacky <thomas.lendacky@amd.com> --- crypto/ahash.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 54 insertions(+), 11 deletions(-)