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Date: Thu, 13 Jun 2019 19:07:16 +0000
From: Horia Geanta <horia.geanta@....com>
To: Christophe Leroy <christophe.leroy@....fr>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>
CC: "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v3 2/4] crypto: talitos - fix hash on SEC1.
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%@...63, <flush>24.19%@...88, 28.63%@...333, <reimport>4.60%@...56, 16.70%@...281] dst_divs=[71.61%@...gnmask+16361, 14.36%@...56, 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%@...378, <reimport>52.0%@...329, 21.42%@...gnmask+16380, 10.2%@...gnmask+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%@...01, <reimport>17.34%@...285, <flush>17.71%@+26, 12.68%@...644] 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%@...790, 17.86%@...29, <reimport>12.64%@...gnmask+16300, 8.29%@+15, 0.40%@...506, <reimport>0.51%@...322, <reimport>0.24%@...339] 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?
> 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@...r.kernel.org
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
> 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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