[v2 PATCH 0/3] crypto: scatterwalk - scatterwalk_next and memcpy_sglist

[v2 PATCH 0/3] crypto: scatterwalk - scatterwalk_next and memcpy_sglist

[Herbert Xu]

v2 incorporates suggestions by Eric Biggers, and makes the addr field
const in struct scatter_walk.

This patch series changes the calling convention of scatterwalk_next
and adds a new helper memcpy_sglist.

Herbert Xu (3):
  crypto: scatterwalk - Change scatterwalk_next calling convention
  crypto: scatterwalk - Add memcpy_sglist
  crypto: skcipher - Eliminate duplicate virt.addr field

 arch/arm/crypto/ghash-ce-glue.c       |  7 ++---
 arch/arm64/crypto/aes-ce-ccm-glue.c   |  9 +++---
 arch/arm64/crypto/ghash-ce-glue.c     |  7 ++---
 arch/arm64/crypto/sm4-ce-ccm-glue.c   |  8 +++---
 arch/arm64/crypto/sm4-ce-gcm-glue.c   |  8 +++---
 arch/s390/crypto/aes_s390.c           | 21 ++++++--------
 arch/x86/crypto/aegis128-aesni-glue.c |  7 ++---
 arch/x86/crypto/aesni-intel_glue.c    |  9 +++---
 crypto/aegis128-core.c                |  7 ++---
 crypto/scatterwalk.c                  | 41 +++++++++++++++++++++------
 crypto/skcipher.c                     | 35 +++++++++++------------
 drivers/crypto/nx/nx.c                |  7 ++---
 include/crypto/algapi.h               |  8 ++++++
 include/crypto/internal/skcipher.h    | 26 +++++++++++++----
 include/crypto/scatterwalk.h          | 38 ++++++++++++++-----------
 15 files changed, 140 insertions(+), 98 deletions(-)

-- 
2.39.5

[v2 PATCH 1/3] crypto: scatterwalk - Change scatterwalk_next calling convention

[Herbert Xu]

Rather than returning the address and storing the length into an
argument pointer, add an address field to the walk struct and use
that to store the address.  The length is returned directly.

Change the done functions to use this stored address instead of
getting them from the caller.

Split the address into two using a union.  The user should only
access the const version so that it is never changed.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 arch/arm/crypto/ghash-ce-glue.c       |  7 +++---
 arch/arm64/crypto/aes-ce-ccm-glue.c   |  9 +++----
 arch/arm64/crypto/ghash-ce-glue.c     |  7 +++---
 arch/arm64/crypto/sm4-ce-ccm-glue.c   |  8 +++---
 arch/arm64/crypto/sm4-ce-gcm-glue.c   |  8 +++---
 arch/s390/crypto/aes_s390.c           | 21 +++++++---------
 arch/x86/crypto/aegis128-aesni-glue.c |  7 +++---
 arch/x86/crypto/aesni-intel_glue.c    |  9 +++----
 crypto/aegis128-core.c                |  7 +++---
 crypto/scatterwalk.c                  | 14 +++++------
 crypto/skcipher.c                     | 10 +++++---
 drivers/crypto/nx/nx.c                |  7 +++---
 include/crypto/algapi.h               |  7 ++++++
 include/crypto/scatterwalk.h          | 35 ++++++++++++++-------------
 14 files changed, 78 insertions(+), 78 deletions(-)

diff --git a/arch/arm/crypto/ghash-ce-glue.c b/arch/arm/crypto/ghash-ce-glue.c
index 9613ffed84f9..dab66b520b6e 100644
--- a/arch/arm/crypto/ghash-ce-glue.c
+++ b/arch/arm/crypto/ghash-ce-glue.c
@@ -460,11 +460,10 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[], u32 len)
 
 	do {
 		unsigned int n;
-		const u8 *p;
 
-		p = scatterwalk_next(&walk, len, &n);
-		gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
-		scatterwalk_done_src(&walk, p, n);
+		n = scatterwalk_next(&walk, len);
+		gcm_update_mac(dg, walk.addr, n, buf, &buf_count, ctx);
+		scatterwalk_done_src(&walk,  n);
 
 		if (unlikely(len / SZ_4K > (len - n) / SZ_4K)) {
 			kernel_neon_end();
diff --git a/arch/arm64/crypto/aes-ce-ccm-glue.c b/arch/arm64/crypto/aes-ce-ccm-glue.c
index 1c29546983bf..2d791d51891b 100644
--- a/arch/arm64/crypto/aes-ce-ccm-glue.c
+++ b/arch/arm64/crypto/aes-ce-ccm-glue.c
@@ -157,12 +157,11 @@ static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 
 	do {
 		unsigned int n;
-		const u8 *p;
 
-		p = scatterwalk_next(&walk, len, &n);
-		macp = ce_aes_ccm_auth_data(mac, p, n, macp, ctx->key_enc,
-					    num_rounds(ctx));
-		scatterwalk_done_src(&walk, p, n);
+		n = scatterwalk_next(&walk, len);
+		macp = ce_aes_ccm_auth_data(mac, walk.addr, n, macp,
+					    ctx->key_enc, num_rounds(ctx));
+		scatterwalk_done_src(&walk, n);
 		len -= n;
 	} while (len);
 }
diff --git a/arch/arm64/crypto/ghash-ce-glue.c b/arch/arm64/crypto/ghash-ce-glue.c
index 69d4fb78c30d..071e122f9c37 100644
--- a/arch/arm64/crypto/ghash-ce-glue.c
+++ b/arch/arm64/crypto/ghash-ce-glue.c
@@ -309,11 +309,10 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[], u32 len)
 
 	do {
 		unsigned int n;
-		const u8 *p;
 
-		p = scatterwalk_next(&walk, len, &n);
-		gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
-		scatterwalk_done_src(&walk, p, n);
+		n = scatterwalk_next(&walk, len);
+		gcm_update_mac(dg, walk.addr, n, buf, &buf_count, ctx);
+		scatterwalk_done_src(&walk, n);
 		len -= n;
 	} while (len);
 
diff --git a/arch/arm64/crypto/sm4-ce-ccm-glue.c b/arch/arm64/crypto/sm4-ce-ccm-glue.c
index 119f86eb7cc9..e9cc1c1364ec 100644
--- a/arch/arm64/crypto/sm4-ce-ccm-glue.c
+++ b/arch/arm64/crypto/sm4-ce-ccm-glue.c
@@ -113,10 +113,10 @@ static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 
 	do {
 		unsigned int n, orig_n;
-		const u8 *p, *orig_p;
+		const u8 *p;
 
-		orig_p = scatterwalk_next(&walk, assoclen, &orig_n);
-		p = orig_p;
+		orig_n = scatterwalk_next(&walk, assoclen);
+		p = walk.addr;
 		n = orig_n;
 
 		while (n > 0) {
@@ -149,7 +149,7 @@ static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 			}
 		}
 
-		scatterwalk_done_src(&walk, orig_p, orig_n);
+		scatterwalk_done_src(&walk, orig_n);
 		assoclen -= orig_n;
 	} while (assoclen);
 }
diff --git a/arch/arm64/crypto/sm4-ce-gcm-glue.c b/arch/arm64/crypto/sm4-ce-gcm-glue.c
index 2e27d7752d4f..c2ea3d5f690b 100644
--- a/arch/arm64/crypto/sm4-ce-gcm-glue.c
+++ b/arch/arm64/crypto/sm4-ce-gcm-glue.c
@@ -83,10 +83,10 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u8 ghash[])
 
 	do {
 		unsigned int n, orig_n;
-		const u8 *p, *orig_p;
+		const u8 *p;
 
-		orig_p = scatterwalk_next(&walk, assoclen, &orig_n);
-		p = orig_p;
+		orig_n = scatterwalk_next(&walk, assoclen);
+		p = walk.addr;
 		n = orig_n;
 
 		if (n + buflen < GHASH_BLOCK_SIZE) {
@@ -118,7 +118,7 @@ static void gcm_calculate_auth_mac(struct aead_request *req, u8 ghash[])
 				memcpy(&buffer[0], p, buflen);
 		}
 
-		scatterwalk_done_src(&walk, orig_p, orig_n);
+		scatterwalk_done_src(&walk, orig_n);
 		assoclen -= orig_n;
 	} while (assoclen);
 
diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c
index 7fd303df05ab..ed85bd6e298f 100644
--- a/arch/s390/crypto/aes_s390.c
+++ b/arch/s390/crypto/aes_s390.c
@@ -66,7 +66,6 @@ struct s390_xts_ctx {
 struct gcm_sg_walk {
 	struct scatter_walk walk;
 	unsigned int walk_bytes;
-	u8 *walk_ptr;
 	unsigned int walk_bytes_remain;
 	u8 buf[AES_BLOCK_SIZE];
 	unsigned int buf_bytes;
@@ -789,8 +788,7 @@ static inline unsigned int _gcm_sg_clamp_and_map(struct gcm_sg_walk *gw)
 {
 	if (gw->walk_bytes_remain == 0)
 		return 0;
-	gw->walk_ptr = scatterwalk_next(&gw->walk, gw->walk_bytes_remain,
-					&gw->walk_bytes);
+	gw->walk_bytes = scatterwalk_next(&gw->walk, gw->walk_bytes_remain);
 	return gw->walk_bytes;
 }
 
@@ -799,10 +797,9 @@ static inline void _gcm_sg_unmap_and_advance(struct gcm_sg_walk *gw,
 {
 	gw->walk_bytes_remain -= nbytes;
 	if (out)
-		scatterwalk_done_dst(&gw->walk, gw->walk_ptr, nbytes);
+		scatterwalk_done_dst(&gw->walk, nbytes);
 	else
-		scatterwalk_done_src(&gw->walk, gw->walk_ptr, nbytes);
-	gw->walk_ptr = NULL;
+		scatterwalk_done_src(&gw->walk, nbytes);
 }
 
 static int gcm_in_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
@@ -828,14 +825,14 @@ static int gcm_in_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
 	}
 
 	if (!gw->buf_bytes && gw->walk_bytes >= minbytesneeded) {
-		gw->ptr = gw->walk_ptr;
+		gw->ptr = gw->walk.addr;
 		gw->nbytes = gw->walk_bytes;
 		goto out;
 	}
 
 	while (1) {
 		n = min(gw->walk_bytes, AES_BLOCK_SIZE - gw->buf_bytes);
-		memcpy(gw->buf + gw->buf_bytes, gw->walk_ptr, n);
+		memcpy(gw->buf + gw->buf_bytes, gw->walk.addr, n);
 		gw->buf_bytes += n;
 		_gcm_sg_unmap_and_advance(gw, n, false);
 		if (gw->buf_bytes >= minbytesneeded) {
@@ -869,13 +866,13 @@ static int gcm_out_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
 	}
 
 	if (gw->walk_bytes >= minbytesneeded) {
-		gw->ptr = gw->walk_ptr;
+		gw->ptr = gw->walk.addr;
 		gw->nbytes = gw->walk_bytes;
 		goto out;
 	}
 
-	scatterwalk_unmap(gw->walk_ptr);
-	gw->walk_ptr = NULL;
+	/* XXX */
+	scatterwalk_unmap(gw->walk.addr);
 
 	gw->ptr = gw->buf;
 	gw->nbytes = sizeof(gw->buf);
@@ -914,7 +911,7 @@ static int gcm_out_walk_done(struct gcm_sg_walk *gw, unsigned int bytesdone)
 			if (!_gcm_sg_clamp_and_map(gw))
 				return i;
 			n = min(gw->walk_bytes, bytesdone - i);
-			memcpy(gw->walk_ptr, gw->buf + i, n);
+			memcpy(gw->walk.addr, gw->buf + i, n);
 			_gcm_sg_unmap_and_advance(gw, n, true);
 		}
 	} else
diff --git a/arch/x86/crypto/aegis128-aesni-glue.c b/arch/x86/crypto/aegis128-aesni-glue.c
index 1bd093d073ed..26786e15abac 100644
--- a/arch/x86/crypto/aegis128-aesni-glue.c
+++ b/arch/x86/crypto/aegis128-aesni-glue.c
@@ -71,10 +71,9 @@ static void crypto_aegis128_aesni_process_ad(
 
 	scatterwalk_start(&walk, sg_src);
 	while (assoclen != 0) {
-		unsigned int size;
-		const u8 *mapped = scatterwalk_next(&walk, assoclen, &size);
+		unsigned int size = scatterwalk_next(&walk, assoclen);
+		const u8 *src = walk.addr;
 		unsigned int left = size;
-		const u8 *src = mapped;
 
 		if (pos + size >= AEGIS128_BLOCK_SIZE) {
 			if (pos > 0) {
@@ -97,7 +96,7 @@ static void crypto_aegis128_aesni_process_ad(
 		pos += left;
 		assoclen -= size;
 
-		scatterwalk_done_src(&walk, mapped, size);
+		scatterwalk_done_src(&walk, size);
 	}
 
 	if (pos > 0) {
diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index c4bd05688b55..e141b7995304 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -1306,12 +1306,11 @@ static void gcm_process_assoc(const struct aes_gcm_key *key, u8 ghash_acc[16],
 	scatterwalk_start(&walk, sg_src);
 
 	while (assoclen) {
-		unsigned int orig_len_this_step;
-		const u8 *orig_src = scatterwalk_next(&walk, assoclen,
-						      &orig_len_this_step);
+		unsigned int orig_len_this_step = scatterwalk_next(
+			&walk, assoclen);
 		unsigned int len_this_step = orig_len_this_step;
 		unsigned int len;
-		const u8 *src = orig_src;
+		const u8 *src = walk.addr;
 
 		if (unlikely(pos)) {
 			len = min(len_this_step, 16 - pos);
@@ -1335,7 +1334,7 @@ static void gcm_process_assoc(const struct aes_gcm_key *key, u8 ghash_acc[16],
 			pos = len_this_step;
 		}
 next:
-		scatterwalk_done_src(&walk, orig_src, orig_len_this_step);
+		scatterwalk_done_src(&walk, orig_len_this_step);
 		if (need_resched()) {
 			kernel_fpu_end();
 			kernel_fpu_begin();
diff --git a/crypto/aegis128-core.c b/crypto/aegis128-core.c
index 15d64d836356..72f6ee1345ef 100644
--- a/crypto/aegis128-core.c
+++ b/crypto/aegis128-core.c
@@ -284,10 +284,9 @@ static void crypto_aegis128_process_ad(struct aegis_state *state,
 
 	scatterwalk_start(&walk, sg_src);
 	while (assoclen != 0) {
-		unsigned int size;
-		const u8 *mapped = scatterwalk_next(&walk, assoclen, &size);
+		unsigned int size = scatterwalk_next(&walk, assoclen);
+		const u8 *src = walk.addr;
 		unsigned int left = size;
-		const u8 *src = mapped;
 
 		if (pos + size >= AEGIS_BLOCK_SIZE) {
 			if (pos > 0) {
@@ -308,7 +307,7 @@ static void crypto_aegis128_process_ad(struct aegis_state *state,
 
 		pos += left;
 		assoclen -= size;
-		scatterwalk_done_src(&walk, mapped, size);
+		scatterwalk_done_src(&walk, size);
 	}
 
 	if (pos > 0) {
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 87c080f565d4..20a28c6d94da 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -34,12 +34,11 @@ inline void memcpy_from_scatterwalk(void *buf, struct scatter_walk *walk,
 				    unsigned int nbytes)
 {
 	do {
-		const void *src_addr;
 		unsigned int to_copy;
 
-		src_addr = scatterwalk_next(walk, nbytes, &to_copy);
-		memcpy(buf, src_addr, to_copy);
-		scatterwalk_done_src(walk, src_addr, to_copy);
+		to_copy = scatterwalk_next(walk, nbytes);
+		memcpy(buf, walk->addr, to_copy);
+		scatterwalk_done_src(walk, to_copy);
 		buf += to_copy;
 		nbytes -= to_copy;
 	} while (nbytes);
@@ -50,12 +49,11 @@ inline void memcpy_to_scatterwalk(struct scatter_walk *walk, const void *buf,
 				  unsigned int nbytes)
 {
 	do {
-		void *dst_addr;
 		unsigned int to_copy;
 
-		dst_addr = scatterwalk_next(walk, nbytes, &to_copy);
-		memcpy(dst_addr, buf, to_copy);
-		scatterwalk_done_dst(walk, dst_addr, to_copy);
+		to_copy = scatterwalk_next(walk, nbytes);
+		memcpy(walk->addr, buf, to_copy);
+		scatterwalk_done_dst(walk, to_copy);
 		buf += to_copy;
 		nbytes -= to_copy;
 	} while (nbytes);
diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 53123d3685d5..92def074374a 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -41,12 +41,16 @@ static int skcipher_walk_next(struct skcipher_walk *walk);
 
 static inline void skcipher_map_src(struct skcipher_walk *walk)
 {
-	walk->src.virt.addr = scatterwalk_map(&walk->in);
+	/* XXX */
+	walk->in.maddr = scatterwalk_map(&walk->in);
+	walk->src.virt.addr = walk->in.addr;
 }
 
 static inline void skcipher_map_dst(struct skcipher_walk *walk)
 {
-	walk->dst.virt.addr = scatterwalk_map(&walk->out);
+	/* XXX */
+	walk->out.maddr = scatterwalk_map(&walk->out);
+	walk->dst.virt.addr = walk->out.addr;
 }
 
 static inline gfp_t skcipher_walk_gfp(struct skcipher_walk *walk)
@@ -120,7 +124,7 @@ int skcipher_walk_done(struct skcipher_walk *walk, int res)
 		goto dst_done;
 	}
 
-	scatterwalk_done_dst(&walk->out, walk->dst.virt.addr, n);
+	scatterwalk_done_dst(&walk->out, n);
 dst_done:
 
 	if (res > 0)
diff --git a/drivers/crypto/nx/nx.c b/drivers/crypto/nx/nx.c
index dd95e5361d88..a3b979193d9b 100644
--- a/drivers/crypto/nx/nx.c
+++ b/drivers/crypto/nx/nx.c
@@ -154,17 +154,16 @@ struct nx_sg *nx_walk_and_build(struct nx_sg       *nx_dst,
 	struct scatter_walk walk;
 	struct nx_sg *nx_sg = nx_dst;
 	unsigned int n, len = *src_len;
-	char *dst;
 
 	/* we need to fast forward through @start bytes first */
 	scatterwalk_start_at_pos(&walk, sg_src, start);
 
 	while (len && (nx_sg - nx_dst) < sglen) {
-		dst = scatterwalk_next(&walk, len, &n);
+		n = scatterwalk_next(&walk, len);
 
-		nx_sg = nx_build_sg_list(nx_sg, dst, &n, sglen - (nx_sg - nx_dst));
+		nx_sg = nx_build_sg_list(nx_sg, walk.addr, &n, sglen - (nx_sg - nx_dst));
 
-		scatterwalk_done_src(&walk, dst, n);
+		scatterwalk_done_src(&walk, n);
 		len -= n;
 	}
 	/* update to_process */
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 11065978d360..8f1dfb758ced 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -54,6 +54,7 @@ struct rtattr;
 struct scatterlist;
 struct seq_file;
 struct sk_buff;
+union crypto_no_such_thing;
 
 struct crypto_type {
 	unsigned int (*ctxsize)(struct crypto_alg *alg, u32 type, u32 mask);
@@ -122,6 +123,12 @@ struct crypto_queue {
 struct scatter_walk {
 	struct scatterlist *sg;
 	unsigned int offset;
+	union {
+		void *const addr;
+
+		/* Private API field, do not touch. */
+		union crypto_no_such_thing *maddr;
+	};
 };
 
 struct crypto_attr_alg {
diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
index 3024adbdd443..791100054f7c 100644
--- a/include/crypto/scatterwalk.h
+++ b/include/crypto/scatterwalk.h
@@ -120,18 +120,20 @@ static inline void *scatterwalk_map(struct scatter_walk *walk)
  * scatterwalk_next() - Get the next data buffer in a scatterlist walk
  * @walk: the scatter_walk
  * @total: the total number of bytes remaining, > 0
- * @nbytes_ret: (out) the next number of bytes available, <= @total
  *
- * Return: A virtual address for the next segment of data from the scatterlist.
- *	   The caller must call scatterwalk_done_src() or scatterwalk_done_dst()
- *	   when it is done using this virtual address.
+ * A virtual address for the next segment of data from the scatterlist will
+ * be placed into @walk->addr.  The caller must call scatterwalk_done_src()
+ * or scatterwalk_done_dst() when it is done using this virtual address.
+ *
+ * Returns: the next number of bytes available, <= @total
  */
-static inline void *scatterwalk_next(struct scatter_walk *walk,
-				     unsigned int total,
-				     unsigned int *nbytes_ret)
+static inline unsigned int scatterwalk_next(struct scatter_walk *walk,
+					    unsigned int total)
 {
-	*nbytes_ret = scatterwalk_clamp(walk, total);
-	return scatterwalk_map(walk);
+	unsigned int nbytes = scatterwalk_clamp(walk, total);
+
+	walk->maddr = scatterwalk_map(walk);
+	return nbytes;
 }
 
 static inline void scatterwalk_unmap(const void *vaddr)
@@ -149,32 +151,31 @@ static inline void scatterwalk_advance(struct scatter_walk *walk,
 /**
  * scatterwalk_done_src() - Finish one step of a walk of source scatterlist
  * @walk: the scatter_walk
- * @vaddr: the address returned by scatterwalk_next()
  * @nbytes: the number of bytes processed this step, less than or equal to the
  *	    number of bytes that scatterwalk_next() returned.
  *
- * Use this if the @vaddr was not written to, i.e. it is source data.
+ * Use this if the mapped address was not written to, i.e. it is source data.
  */
 static inline void scatterwalk_done_src(struct scatter_walk *walk,
-					const void *vaddr, unsigned int nbytes)
+					unsigned int nbytes)
 {
-	scatterwalk_unmap(vaddr);
+	scatterwalk_unmap(walk->addr);
 	scatterwalk_advance(walk, nbytes);
 }
 
 /**
  * scatterwalk_done_dst() - Finish one step of a walk of destination scatterlist
  * @walk: the scatter_walk
- * @vaddr: the address returned by scatterwalk_next()
  * @nbytes: the number of bytes processed this step, less than or equal to the
  *	    number of bytes that scatterwalk_next() returned.
  *
- * Use this if the @vaddr may have been written to, i.e. it is destination data.
+ * Use this if the mapped address may have been written to, i.e. it is
+ * destination data.
  */
 static inline void scatterwalk_done_dst(struct scatter_walk *walk,
-					void *vaddr, unsigned int nbytes)
+					unsigned int nbytes)
 {
-	scatterwalk_unmap(vaddr);
+	scatterwalk_unmap(walk->addr);
 	/*
 	 * Explicitly check ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE instead of just
 	 * relying on flush_dcache_page() being a no-op when not implemented,
-- 
2.39.5

Re: [v2 PATCH 1/3] crypto: scatterwalk - Change scatterwalk_next calling convention

[Eric Biggers]

On Fri, Mar 07, 2025 at 11:36:16AM +0800, Herbert Xu wrote:
> diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
> index 11065978d360..8f1dfb758ced 100644
> --- a/include/crypto/algapi.h
> +++ b/include/crypto/algapi.h
> @@ -54,6 +54,7 @@ struct rtattr;
>  struct scatterlist;
>  struct seq_file;
>  struct sk_buff;
> +union crypto_no_such_thing;
>  
>  struct crypto_type {
>  	unsigned int (*ctxsize)(struct crypto_alg *alg, u32 type, u32 mask);
> @@ -122,6 +123,12 @@ struct crypto_queue {
>  struct scatter_walk {
>  	struct scatterlist *sg;
>  	unsigned int offset;
> +	union {
> +		void *const addr;
> +
> +		/* Private API field, do not touch. */
> +		union crypto_no_such_thing *maddr;
> +	};
>  };

This is okay (it makes it a bit easier to accidentally use addr after it was
unmapped, but it's probably worth the simplification in code), but I think using
'void *__addr' would be more consistent with other places in the kernel that use
a similar trick to have something both const and non-const.  For example
struct inode in include/linux/fs.h has i_nlink and __i_nlink.

- Eric

Re: [v2 PATCH 1/3] crypto: scatterwalk - Change scatterwalk_next calling convention

[Herbert Xu]

On Fri, Mar 07, 2025 at 01:43:49PM -0800, Eric Biggers wrote:
>
> This is okay (it makes it a bit easier to accidentally use addr after it was
> unmapped, but it's probably worth the simplification in code), but I think using
> 'void *__addr' would be more consistent with other places in the kernel that use
> a similar trick to have something both const and non-const.  For example
> struct inode in include/linux/fs.h has i_nlink and __i_nlink.

OK I'll rename this.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

[v2 PATCH 2/3] crypto: scatterwalk - Add memcpy_sglist

[Herbert Xu]

Add memcpy_sglist which copies one SG list to another.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 crypto/scatterwalk.c         | 27 +++++++++++++++++++++++++++
 include/crypto/scatterwalk.h |  3 +++
 2 files changed, 30 insertions(+)

diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 20a28c6d94da..8225801488d5 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -86,6 +86,33 @@ void memcpy_to_sglist(struct scatterlist *sg, unsigned int start,
 }
 EXPORT_SYMBOL_GPL(memcpy_to_sglist);
 
+void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src,
+		   unsigned int nbytes)
+{
+	struct scatter_walk swalk;
+	struct scatter_walk dwalk;
+
+	if (unlikely(nbytes == 0)) /* in case sg == NULL */
+		return;
+
+	scatterwalk_start(&swalk, src);
+	scatterwalk_start(&dwalk, dst);
+
+	do {
+		unsigned int slen, dlen;
+		unsigned int len;
+
+		slen = scatterwalk_next(&swalk, nbytes);
+		dlen = scatterwalk_next(&dwalk, nbytes);
+		len = min(slen, dlen);
+		memcpy(dwalk.addr, swalk.addr, len);
+		scatterwalk_done_dst(&dwalk, len);
+		scatterwalk_done_src(&swalk, len);
+		nbytes -= len;
+	} while (nbytes);
+}
+EXPORT_SYMBOL_GPL(memcpy_sglist);
+
 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 				     struct scatterlist *src,
 				     unsigned int len)
diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
index 791100054f7c..533e52dd7e0f 100644
--- a/include/crypto/scatterwalk.h
+++ b/include/crypto/scatterwalk.h
@@ -210,6 +210,9 @@ void memcpy_from_sglist(void *buf, struct scatterlist *sg,
 void memcpy_to_sglist(struct scatterlist *sg, unsigned int start,
 		      const void *buf, unsigned int nbytes);
 
+void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src,
+		   unsigned int nbytes);
+
 /* In new code, please use memcpy_{from,to}_sglist() directly instead. */
 static inline void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 					    unsigned int start,
-- 
2.39.5

Re: [v2 PATCH 2/3] crypto: scatterwalk - Add memcpy_sglist

[Eric Biggers]

On Fri, Mar 07, 2025 at 11:36:19AM +0800, Herbert Xu wrote:
> Add memcpy_sglist which copies one SG list to another.
> 
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

There's no user of this yet, but presumably this is going to be used to replace
some of the bizarre code that is using the "null skcipher" to copy between two
scatterlists?  For example the code in crypto/seqiv.c.

- Eric

Re: [v2 PATCH 2/3] crypto: scatterwalk - Add memcpy_sglist

[Herbert Xu]

On Fri, Mar 07, 2025 at 01:37:49PM -0800, Eric Biggers wrote:
>
> There's no user of this yet, but presumably this is going to be used to replace
> some of the bizarre code that is using the "null skcipher" to copy between two
> scatterlists?  For example the code in crypto/seqiv.c.

It was actually for zram:

https://lore.kernel.org/all/Z8kiRym1hS9fB2mE@gondor.apana.org.au/

But yes we could definitely replace the null skcipher with this.
Do you want to have a go at that?

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [v2 PATCH 2/3] crypto: scatterwalk - Add memcpy_sglist

[Eric Biggers]

On Sat, Mar 08, 2025 at 06:52:35PM +0800, Herbert Xu wrote:
> On Fri, Mar 07, 2025 at 01:37:49PM -0800, Eric Biggers wrote:
> >
> > There's no user of this yet, but presumably this is going to be used to replace
> > some of the bizarre code that is using the "null skcipher" to copy between two
> > scatterlists?  For example the code in crypto/seqiv.c.
> 
> It was actually for zram:
> 
> https://lore.kernel.org/all/Z8kiRym1hS9fB2mE@gondor.apana.org.au/
> 
> But yes we could definitely replace the null skcipher with this.
> Do you want to have a go at that?
> 

Yes, I'll do that.

- Eric

Re: [v2 PATCH 2/3] crypto: scatterwalk - Add memcpy_sglist

[Eric Biggers]

On Fri, Mar 07, 2025 at 11:36:19AM +0800, Herbert Xu wrote:
> Add memcpy_sglist which copies one SG list to another.
> 
> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
> ---
>  crypto/scatterwalk.c         | 27 +++++++++++++++++++++++++++
>  include/crypto/scatterwalk.h |  3 +++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
> index 20a28c6d94da..8225801488d5 100644
> --- a/crypto/scatterwalk.c
> +++ b/crypto/scatterwalk.c
> @@ -86,6 +86,33 @@ void memcpy_to_sglist(struct scatterlist *sg, unsigned int start,
>  }
>  EXPORT_SYMBOL_GPL(memcpy_to_sglist);
>  
> +void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src,
> +		   unsigned int nbytes)
> +{
> +	struct scatter_walk swalk;
> +	struct scatter_walk dwalk;
> +
> +	if (unlikely(nbytes == 0)) /* in case sg == NULL */
> +		return;
> +
> +	scatterwalk_start(&swalk, src);
> +	scatterwalk_start(&dwalk, dst);
> +
> +	do {
> +		unsigned int slen, dlen;
> +		unsigned int len;
> +
> +		slen = scatterwalk_next(&swalk, nbytes);
> +		dlen = scatterwalk_next(&dwalk, nbytes);
> +		len = min(slen, dlen);
> +		memcpy(dwalk.addr, swalk.addr, len);
> +		scatterwalk_done_dst(&dwalk, len);
> +		scatterwalk_done_src(&swalk, len);
> +		nbytes -= len;
> +	} while (nbytes);
> +}
> +EXPORT_SYMBOL_GPL(memcpy_sglist);

Actually this new function is useless as-is, since it invokes undefined behavior
when the source and destination coincide (which can happen even when src ==
dst), and all the potential callers need to handle that case.  I'm working on a
fixed version.

- Eric

Re: [v2 PATCH 2/3] crypto: scatterwalk - Add memcpy_sglist

[Herbert Xu]

On Mon, Mar 10, 2025 at 09:36:51PM -0700, Eric Biggers wrote:
>
> Actually this new function is useless as-is, since it invokes undefined behavior
> when the source and destination coincide (which can happen even when src ==
> dst), and all the potential callers need to handle that case.  I'm working on a
> fixed version.

Yes I just tried using it in chacha20poly1305 and it was no good,
as it can't deal with the partially identical SG lists that IPsec
creates.

So I've fixed it by rewriting it based on skcipher_walk.  In order
to do so I've moved the common bits of skcipher_walk out of skcipher
and into scatterwalk.

This should be good enough to replace skcipher_null.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

[v2 PATCH 3/3] crypto: skcipher - Eliminate duplicate virt.addr field

[Herbert Xu]

Reuse the addr field from struct scatter_walk for skcipher_walk.

Keep the existing virt.addr fields but make them const for the
user to access the mapped address.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 crypto/skcipher.c                  | 29 ++++++++++++-----------------
 include/crypto/algapi.h            |  5 +++--
 include/crypto/internal/skcipher.h | 26 +++++++++++++++++++++-----
 3 files changed, 36 insertions(+), 24 deletions(-)

diff --git a/crypto/skcipher.c b/crypto/skcipher.c
index 92def074374a..24bb78f45bfb 100644
--- a/crypto/skcipher.c
+++ b/crypto/skcipher.c
@@ -43,14 +43,12 @@ static inline void skcipher_map_src(struct skcipher_walk *walk)
 {
 	/* XXX */
 	walk->in.maddr = scatterwalk_map(&walk->in);
-	walk->src.virt.addr = walk->in.addr;
 }
 
 static inline void skcipher_map_dst(struct skcipher_walk *walk)
 {
 	/* XXX */
 	walk->out.maddr = scatterwalk_map(&walk->out);
-	walk->dst.virt.addr = walk->out.addr;
 }
 
 static inline gfp_t skcipher_walk_gfp(struct skcipher_walk *walk)
@@ -100,8 +98,7 @@ int skcipher_walk_done(struct skcipher_walk *walk, int res)
 				    SKCIPHER_WALK_DIFF)))) {
 		scatterwalk_advance(&walk->in, n);
 	} else if (walk->flags & SKCIPHER_WALK_DIFF) {
-		scatterwalk_unmap(walk->src.virt.addr);
-		scatterwalk_advance(&walk->in, n);
+		scatterwalk_done_src(&walk->in, n);
 	} else if (walk->flags & SKCIPHER_WALK_COPY) {
 		scatterwalk_advance(&walk->in, n);
 		skcipher_map_dst(walk);
@@ -116,11 +113,8 @@ int skcipher_walk_done(struct skcipher_walk *walk, int res)
 			 */
 			res = -EINVAL;
 			total = 0;
-		} else {
-			u8 *buf = PTR_ALIGN(walk->buffer, walk->alignmask + 1);
-
-			memcpy_to_scatterwalk(&walk->out, buf, n);
-		}
+		} else
+			memcpy_to_scatterwalk(&walk->out, walk->out.addr, n);
 		goto dst_done;
 	}
 
@@ -162,7 +156,7 @@ static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize)
 {
 	unsigned alignmask = walk->alignmask;
 	unsigned n;
-	u8 *buffer;
+	void *buffer;
 
 	if (!walk->buffer)
 		walk->buffer = walk->page;
@@ -176,10 +170,11 @@ static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize)
 			return skcipher_walk_done(walk, -ENOMEM);
 		walk->buffer = buffer;
 	}
-	walk->dst.virt.addr = PTR_ALIGN(buffer, alignmask + 1);
-	walk->src.virt.addr = walk->dst.virt.addr;
 
-	memcpy_from_scatterwalk(walk->src.virt.addr, &walk->in, bsize);
+	buffer = PTR_ALIGN(buffer, alignmask + 1);
+	memcpy_from_scatterwalk(buffer, &walk->in, bsize);
+	walk->out.maddr = buffer;
+	walk->in.maddr = walk->out.maddr;
 
 	walk->nbytes = bsize;
 	walk->flags |= SKCIPHER_WALK_SLOW;
@@ -189,7 +184,7 @@ static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize)
 
 static int skcipher_next_copy(struct skcipher_walk *walk)
 {
-	u8 *tmp = walk->page;
+	void *tmp = walk->page;
 
 	skcipher_map_src(walk);
 	memcpy(tmp, walk->src.virt.addr, walk->nbytes);
@@ -199,8 +194,8 @@ static int skcipher_next_copy(struct skcipher_walk *walk)
 	 * processed (which might be less than walk->nbytes) is known.
 	 */
 
-	walk->src.virt.addr = tmp;
-	walk->dst.virt.addr = tmp;
+	walk->in.maddr = tmp;
+	walk->out.maddr = tmp;
 	return 0;
 }
 
@@ -214,7 +209,7 @@ static int skcipher_next_fast(struct skcipher_walk *walk)
 		(u8 *)(sg_page(walk->out.sg) + (walk->out.offset >> PAGE_SHIFT));
 
 	skcipher_map_src(walk);
-	walk->dst.virt.addr = walk->src.virt.addr;
+	walk->out.maddr = walk->in.maddr;
 
 	if (diff) {
 		walk->flags |= SKCIPHER_WALK_DIFF;
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index 8f1dfb758ced..79ccd8ab287a 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -121,14 +121,15 @@ struct crypto_queue {
 };
 
 struct scatter_walk {
-	struct scatterlist *sg;
-	unsigned int offset;
+	/* Must be the first member, see struct skcipher_walk. */
 	union {
 		void *const addr;
 
 		/* Private API field, do not touch. */
 		union crypto_no_such_thing *maddr;
 	};
+	struct scatterlist *sg;
+	unsigned int offset;
 };
 
 struct crypto_attr_alg {
diff --git a/include/crypto/internal/skcipher.h b/include/crypto/internal/skcipher.h
index d6ae7a86fed2..c705124432c5 100644
--- a/include/crypto/internal/skcipher.h
+++ b/include/crypto/internal/skcipher.h
@@ -56,15 +56,31 @@ struct crypto_lskcipher_spawn {
 
 struct skcipher_walk {
 	union {
+		/* Virtual address of the source. */
 		struct {
-			void *addr;
-		} virt;
-	} src, dst;
+			struct {
+				void *const addr;
+			} virt;
+		} src;
+
+		/* Private field for the API, do not use. */
+		struct scatter_walk in;
+	};
 
-	struct scatter_walk in;
 	unsigned int nbytes;
 
-	struct scatter_walk out;
+	union {
+		/* Virtual address of the destination. */
+		struct {
+			struct {
+				void *const addr;
+			} virt;
+		} dst;
+
+		/* Private field for the API, do not use. */
+		struct scatter_walk out;
+	};
+
 	unsigned int total;
 
 	u8 *page;
-- 
2.39.5

Re: [v2 PATCH 3/3] crypto: skcipher - Eliminate duplicate virt.addr field

[Eric Biggers]

On Fri, Mar 07, 2025 at 11:36:21AM +0800, Herbert Xu wrote:
> diff --git a/crypto/skcipher.c b/crypto/skcipher.c
> index 92def074374a..24bb78f45bfb 100644
> --- a/crypto/skcipher.c
> +++ b/crypto/skcipher.c
> @@ -43,14 +43,12 @@ static inline void skcipher_map_src(struct skcipher_walk *walk)
>  {
>  	/* XXX */
>  	walk->in.maddr = scatterwalk_map(&walk->in);
> -	walk->src.virt.addr = walk->in.addr;
>  }

This patch makes all the callers of scatterwalk_map() assign the returned
address to the struct scatter_walk itself.  So that should just be done by
scatterwalk_map() itself.  Then skcipher_map_src() and skcipher_map_dst() should
be removed and the callers updated to use scatterwalk_map(&walk->in) and
scatterwalk_map(&walk->out) directly.

> @@ -214,7 +209,7 @@ static int skcipher_next_fast(struct skcipher_walk *walk)
>  		(u8 *)(sg_page(walk->out.sg) + (walk->out.offset >> PAGE_SHIFT));
>  
>  	skcipher_map_src(walk);
> -	walk->dst.virt.addr = walk->src.virt.addr;
> +	walk->out.maddr = walk->in.maddr;
>  
>  	if (diff) {
>  		walk->flags |= SKCIPHER_WALK_DIFF;

Note that this will have to be rebased on top of
https://lore.kernel.org/r/20250306033305.163767-1-ebiggers@kernel.org
(sorry for missing that earlier).

- Eric