Re: [PATCH v3 2/4] crypto: talitos - fix hash on SEC1.

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Le 13/06/2019 à 21:07, Horia Geanta a écrit :

On 6/13/2019 3:48 PM, Christophe Leroy wrote:

On SEC1, hash provides wrong result when performing hashing in several
steps with input data SG list has more than one element. This was
detected with CONFIG_CRYPTO_MANAGER_EXTRA_TESTS:

[   44.185947] alg: hash: md5-talitos test failed (wrong result) on test vector 6, cfg="random: may_sleep use_finup src_divs=[<reimport>25.88%@+8063, <flush>24.19%@+9588, 28.63%@+16333, <reimport>4.60%@+6756, 16.70%@+16281] dst_divs=[71.61%@alignmask+16361, 14.36%@+7756, 14.3%@+"
[   44.325122] alg: hash: sha1-talitos test failed (wrong result) on test vector 3, cfg="random: inplace use_final src_divs=[<flush,nosimd>16.56%@+16378, <reimport>52.0%@+16329, 21.42%@alignmask+16380, 10.2%@alignmask+16380] iv_offset=39"
[   44.493500] alg: hash: sha224-talitos test failed (wrong result) on test vector 4, cfg="random: use_final nosimd src_divs=[<reimport>52.27%@+7401, <reimport>17.34%@+16285, <flush>17.71%@+26, 12.68%@+10644] iv_offset=43"
[   44.673262] alg: hash: sha256-talitos test failed (wrong result) on test vector 4, cfg="random: may_sleep use_finup src_divs=[<reimport>60.6%@+12790, 17.86%@+1329, <reimport>12.64%@alignmask+16300, 8.29%@+15, 0.40%@+13506, <reimport>0.51%@+16322, <reimport>0.24%@+16339] dst_divs"

This is due to two issues:
- We have an overlap between the buffer used for copying the input
data (SEC1 doesn't do scatter/gather) and the chained descriptor.
- Data copy is wrong when the previous hash left less than one
blocksize of data to hash, implying a complement of the previous
block with a few bytes from the new request.


I fail to spot these issues.

IIUC in case of SEC1, the variable part of talitos_edesc structure contains
a 2nd "chained" descriptor (talitos_desc struct) followed by an area
dedicated to linearizing the input (in case input is scattered).

Where is the overlap?
talitos_sg_map() maps the area starting at edesc->dma_link_tbl, which corresponds to the start of the variable part of talitos_edesc structure. When we use the second descriptor, the data is after that descriptor, but talitos_sg_map() is not aware of it so it maps the second descriptor followed by part of the data instead of mapping the data. 

Christophe





Fix it by:
- Moving the second descriptor after the buffer, as moving the buffer
after the descriptor would make it more complex for other cipher
operations (AEAD, ABLKCIPHER)
- Rebuiding a new data SG list without the bytes taken from the new
request to complete the previous one.

Preceding patch ("crypto: talitos - move struct talitos_edesc into
talitos.h") as required for this change to build properly.

Fixes: 37b5e8897eb5 ("crypto: talitos - chain in buffered data for ahash on SEC1")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
  drivers/crypto/talitos.c | 63 ++++++++++++++++++++++++++++++------------------
  1 file changed, 40 insertions(+), 23 deletions(-)

diff --git a/drivers/crypto/talitos.c b/drivers/crypto/talitos.c
index 5b401aec6c84..4f03baef952b 100644
--- a/drivers/crypto/talitos.c
+++ b/drivers/crypto/talitos.c
@@ -336,15 +336,18 @@ static void flush_channel(struct device *dev, int ch, int error, int reset_ch)
  	tail = priv->chan[ch].tail;
  	while (priv->chan[ch].fifo[tail].desc) {
  		__be32 hdr;
+		struct talitos_edesc *edesc;
request = &priv->chan[ch].fifo[tail]; 
+		edesc = container_of(request->desc, struct talitos_edesc, desc);
/* descriptors with their done bits set don't get the error */ 
  		rmb();
  		if (!is_sec1)
  			hdr = request->desc->hdr;
  		else if (request->desc->next_desc)
-			hdr = (request->desc + 1)->hdr1;
+			hdr = ((struct talitos_desc *)
+			       (edesc->buf + edesc->dma_len))->hdr1;
  		else
  			hdr = request->desc->hdr1;
@@ -476,8 +479,14 @@ static u32 current_desc_hdr(struct device *dev, int ch) 
  		}
  	}
- if (priv->chan[ch].fifo[iter].desc->next_desc == cur_desc) 
-		return (priv->chan[ch].fifo[iter].desc + 1)->hdr;
+	if (priv->chan[ch].fifo[iter].desc->next_desc == cur_desc) {
+		struct talitos_edesc *edesc;
+
+		edesc = container_of(priv->chan[ch].fifo[iter].desc,
+				     struct talitos_edesc, desc);
+		return ((struct talitos_desc *)
+			(edesc->buf + edesc->dma_len))->hdr;
+	}
return priv->chan[ch].fifo[iter].desc->hdr; 
  }
@@ -1402,15 +1411,11 @@ static struct talitos_edesc *talitos_edesc_alloc(struct device *dev,
  	edesc->dst_nents = dst_nents;
  	edesc->iv_dma = iv_dma;
  	edesc->dma_len = dma_len;
-	if (dma_len) {
-		void *addr = &edesc->link_tbl[0];
-
-		if (is_sec1 && !dst)
-			addr += sizeof(struct talitos_desc);
-		edesc->dma_link_tbl = dma_map_single(dev, addr,
+	if (dma_len)
+		edesc->dma_link_tbl = dma_map_single(dev, &edesc->link_tbl[0],
  						     edesc->dma_len,
  						     DMA_BIDIRECTIONAL);
-	}
+
  	return edesc;
  }
@@ -1722,14 +1727,16 @@ static void common_nonsnoop_hash_unmap(struct device *dev, 
  	struct talitos_private *priv = dev_get_drvdata(dev);
  	bool is_sec1 = has_ftr_sec1(priv);
  	struct talitos_desc *desc = &edesc->desc;
-	struct talitos_desc *desc2 = desc + 1;
+	struct talitos_desc *desc2 = (struct talitos_desc *)
+				     (edesc->buf + edesc->dma_len);
unmap_single_talitos_ptr(dev, &edesc->desc.ptr[5], DMA_FROM_DEVICE); 
  	if (desc->next_desc &&
  	    desc->ptr[5].ptr != desc2->ptr[5].ptr)
  		unmap_single_talitos_ptr(dev, &desc2->ptr[5], DMA_FROM_DEVICE);
- talitos_sg_unmap(dev, edesc, req_ctx->psrc, NULL, 0, 0); 
+	if (req_ctx->psrc)
+		talitos_sg_unmap(dev, edesc, req_ctx->psrc, NULL, 0, 0);
/* When using hashctx-in, must unmap it. */ 
  	if (from_talitos_ptr_len(&edesc->desc.ptr[1], is_sec1))
@@ -1796,7 +1803,6 @@ static void talitos_handle_buggy_hash(struct talitos_ctx *ctx,
static int common_nonsnoop_hash(struct talitos_edesc *edesc, 
  				struct ahash_request *areq, unsigned int length,
-				unsigned int offset,
  				void (*callback) (struct device *dev,
  						  struct talitos_desc *desc,
  						  void *context, int error))
@@ -1835,9 +1841,7 @@ static int common_nonsnoop_hash(struct talitos_edesc *edesc,
sg_count = edesc->src_nents ?: 1; 
  	if (is_sec1 && sg_count > 1)
-		sg_pcopy_to_buffer(req_ctx->psrc, sg_count,
-				   edesc->buf + sizeof(struct talitos_desc),
-				   length, req_ctx->nbuf);
+		sg_copy_to_buffer(req_ctx->psrc, sg_count, edesc->buf, length);
  	else if (length)
  		sg_count = dma_map_sg(dev, req_ctx->psrc, sg_count,
  				      DMA_TO_DEVICE);
@@ -1850,7 +1854,7 @@ static int common_nonsnoop_hash(struct talitos_edesc *edesc,
  				       DMA_TO_DEVICE);
  	} else {
  		sg_count = talitos_sg_map(dev, req_ctx->psrc, length, edesc,
-					  &desc->ptr[3], sg_count, offset, 0);
+					  &desc->ptr[3], sg_count, 0, 0);
  		if (sg_count > 1)
  			sync_needed = true;
  	}
@@ -1874,7 +1878,8 @@ static int common_nonsnoop_hash(struct talitos_edesc *edesc,
  		talitos_handle_buggy_hash(ctx, edesc, &desc->ptr[3]);
if (is_sec1 && req_ctx->nbuf && length) { 
-		struct talitos_desc *desc2 = desc + 1;
+		struct talitos_desc *desc2 = (struct talitos_desc *)
+					     (edesc->buf + edesc->dma_len);
  		dma_addr_t next_desc;
memset(desc2, 0, sizeof(*desc2)); 
@@ -1895,7 +1900,7 @@ static int common_nonsnoop_hash(struct talitos_edesc *edesc,
  						      DMA_TO_DEVICE);
  		copy_talitos_ptr(&desc2->ptr[2], &desc->ptr[2], is_sec1);
  		sg_count = talitos_sg_map(dev, req_ctx->psrc, length, edesc,
-					  &desc2->ptr[3], sg_count, offset, 0);
+					  &desc2->ptr[3], sg_count, 0, 0);
  		if (sg_count > 1)
  			sync_needed = true;
  		copy_talitos_ptr(&desc2->ptr[5], &desc->ptr[5], is_sec1);
@@ -2006,7 +2011,6 @@ static int ahash_process_req(struct ahash_request *areq, unsigned int nbytes)
  	struct device *dev = ctx->dev;
  	struct talitos_private *priv = dev_get_drvdata(dev);
  	bool is_sec1 = has_ftr_sec1(priv);
-	int offset = 0;
  	u8 *ctx_buf = req_ctx->buf[req_ctx->buf_idx];
if (!req_ctx->last && (nbytes + req_ctx->nbuf <= blocksize)) { 
@@ -2046,6 +2050,9 @@ static int ahash_process_req(struct ahash_request *areq, unsigned int nbytes)
  			sg_chain(req_ctx->bufsl, 2, areq->src);
  		req_ctx->psrc = req_ctx->bufsl;
  	} else if (is_sec1 && req_ctx->nbuf && req_ctx->nbuf < blocksize) {
+		int offset;
+		struct scatterlist *sg;
+
  		if (nbytes_to_hash > blocksize)
  			offset = blocksize - req_ctx->nbuf;
  		else
@@ -2058,7 +2065,18 @@ static int ahash_process_req(struct ahash_request *areq, unsigned int nbytes)
  		sg_copy_to_buffer(areq->src, nents,
  				  ctx_buf + req_ctx->nbuf, offset);
  		req_ctx->nbuf += offset;
-		req_ctx->psrc = areq->src;
+		for (sg = areq->src; sg && offset >= sg->length;
+		     offset -= sg->length, sg = sg_next(sg))
+			;
+		if (offset) {
+			sg_init_table(req_ctx->bufsl, 2);
+			sg_set_buf(req_ctx->bufsl, sg_virt(sg) + offset,
+				   sg->length - offset);
+			sg_chain(req_ctx->bufsl, 2, sg_next(sg));
+			req_ctx->psrc = req_ctx->bufsl;
+		} else {
+			req_ctx->psrc = sg;
+		}
  	} else
  		req_ctx->psrc = areq->src;
@@ -2098,8 +2116,7 @@ static int ahash_process_req(struct ahash_request *areq, unsigned int nbytes) 
  	if (ctx->keylen && (req_ctx->first || req_ctx->last))
  		edesc->desc.hdr |= DESC_HDR_MODE0_MDEU_HMAC;
- return common_nonsnoop_hash(edesc, areq, nbytes_to_hash, offset, 
-				    ahash_done);
+	return common_nonsnoop_hash(edesc, areq, nbytes_to_hash, ahash_done);
  }
static int ahash_update(struct ahash_request *areq)
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