[PATCH v3 1/4] lib/mpi: only require buffers as big as needed for the integer

[PATCH v3 1/4] lib/mpi: only require buffers as big as needed for the integer

[Andrew Zaborowski]

Since mpi_write_to_sgl and mpi_read_buffer explicitly left-align the
integers being written it makes no sense to require a buffer big enough for
the number + the leading zero bytes which are not written.  The error
returned also doesn't convey any information.  So instead require only the
size needed and return -EOVERFLOW to signal when buffer too short.

Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
---
No changes since v1
---
 lib/mpi/mpicoder.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index c7e0a70..074d2df 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -135,7 +135,9 @@ EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
  * @buf:	bufer to which the output will be written to. Needs to be at
  *		leaset mpi_get_size(a) long.
  * @buf_len:	size of the buf.
- * @nbytes:	receives the actual length of the data written.
+ * @nbytes:	receives the actual length of the data written on success and
+ *		the data to-be-written on -EOVERFLOW in case buf_len was too
+ *		small.
  * @sign:	if not NULL, it will be set to the sign of a.
  *
  * Return:	0 on success or error code in case of error
@@ -148,7 +150,7 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
 	unsigned int n = mpi_get_size(a);
 	int i, lzeros = 0;
 
-	if (buf_len < n || !buf || !nbytes)
+	if (!buf || !nbytes)
 		return -EINVAL;
 
 	if (sign)
@@ -163,6 +165,11 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
 			break;
 	}
 
+	if (buf_len < n - lzeros) {
+		*nbytes = n - lzeros;
+		return -EOVERFLOW;
+	}
+
 	p = buf;
 	*nbytes = n - lzeros;
 
@@ -332,7 +339,8 @@ EXPORT_SYMBOL_GPL(mpi_set_buffer);
  * @nbytes:	in/out param - it has the be set to the maximum number of
  *		bytes that can be written to sgl. This has to be at least
  *		the size of the integer a. On return it receives the actual
- *		length of the data written.
+ *		length of the data written on success or the data that would
+ *		be written if buffer was too small.
  * @sign:	if not NULL, it will be set to the sign of a.
  *
  * Return:	0 on success or error code in case of error
@@ -345,7 +353,7 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
 	unsigned int n = mpi_get_size(a);
 	int i, x, y = 0, lzeros = 0, buf_len;
 
-	if (!nbytes || *nbytes < n)
+	if (!nbytes)
 		return -EINVAL;
 
 	if (sign)
@@ -360,6 +368,11 @@ int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned *nbytes,
 			break;
 	}
 
+	if (*nbytes < n - lzeros) {
+		*nbytes = n - lzeros;
+		return -EOVERFLOW;
+	}
+
 	*nbytes = n - lzeros;
 	buf_len = sgl->length;
 	p2 = sg_virt(sgl);
-- 
2.1.4

[PATCH v3 2/4] crypto: rsa: only require output buffers as big as needed.

[Andrew Zaborowski]

rhe RSA operations explicitly left-align the integers being written
skipping any leading zero bytes, but still require the output buffers to
include just enough space for the integer + the leading zero bytes.
Since the size of integer + the leading zero bytes (i.e. the key modulus
size) can now be obtained more easily through crypto_akcipher_maxsize
change the operations to only require as big a buffer as actually needed
if the caller has that information.  The semantics for request->dst_len
don't change.

Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
---
No changes since v1
---
 crypto/rsa.c | 24 ------------------------
 1 file changed, 24 deletions(-)

diff --git a/crypto/rsa.c b/crypto/rsa.c
index 1093e04..58aad69 100644
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -91,12 +91,6 @@ static int rsa_enc(struct akcipher_request *req)
 		goto err_free_c;
 	}
 
-	if (req->dst_len < mpi_get_size(pkey->n)) {
-		req->dst_len = mpi_get_size(pkey->n);
-		ret = -EOVERFLOW;
-		goto err_free_c;
-	}
-
 	ret = -ENOMEM;
 	m = mpi_read_raw_from_sgl(req->src, req->src_len);
 	if (!m)
@@ -136,12 +130,6 @@ static int rsa_dec(struct akcipher_request *req)
 		goto err_free_m;
 	}
 
-	if (req->dst_len < mpi_get_size(pkey->n)) {
-		req->dst_len = mpi_get_size(pkey->n);
-		ret = -EOVERFLOW;
-		goto err_free_m;
-	}
-
 	ret = -ENOMEM;
 	c = mpi_read_raw_from_sgl(req->src, req->src_len);
 	if (!c)
@@ -180,12 +168,6 @@ static int rsa_sign(struct akcipher_request *req)
 		goto err_free_s;
 	}
 
-	if (req->dst_len < mpi_get_size(pkey->n)) {
-		req->dst_len = mpi_get_size(pkey->n);
-		ret = -EOVERFLOW;
-		goto err_free_s;
-	}
-
 	ret = -ENOMEM;
 	m = mpi_read_raw_from_sgl(req->src, req->src_len);
 	if (!m)
@@ -225,12 +207,6 @@ static int rsa_verify(struct akcipher_request *req)
 		goto err_free_m;
 	}
 
-	if (req->dst_len < mpi_get_size(pkey->n)) {
-		req->dst_len = mpi_get_size(pkey->n);
-		ret = -EOVERFLOW;
-		goto err_free_m;
-	}
-
 	ret = -ENOMEM;
 	s = mpi_read_raw_from_sgl(req->src, req->src_len);
 	if (!s) {
-- 
2.1.4

[PATCH v3 3/4] crypto: akcipher: add akcipher declarations useful for templates.

[Andrew Zaborowski]

Expose crypto_akcipher_type like other crypto types are exposed to be
used from outside akcipher.c.  Add a struct akcipher_instance similar to
aead_instance with just the right size for an akcipher template
instance, and two macros for converting to/from crypto_instance.

Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
---
v2: no changes since v1
v3: drop the new crypto_akcipher_type methods and
    add struct akcipher_instance
---
 crypto/akcipher.c                  |  3 ++-
 include/crypto/algapi.h            |  1 +
 include/crypto/internal/akcipher.h | 23 +++++++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/crypto/akcipher.c b/crypto/akcipher.c
index 120ec04..d4bb42c 100644
--- a/crypto/akcipher.c
+++ b/crypto/akcipher.c
@@ -75,7 +75,7 @@ static int crypto_akcipher_init_tfm(struct crypto_tfm *tfm)
 	return 0;
 }
 
-static const struct crypto_type crypto_akcipher_type = {
+const struct crypto_type crypto_akcipher_type = {
 	.extsize = crypto_alg_extsize,
 	.init_tfm = crypto_akcipher_init_tfm,
 #ifdef CONFIG_PROC_FS
@@ -87,6 +87,7 @@ static const struct crypto_type crypto_akcipher_type = {
 	.type = CRYPTO_ALG_TYPE_AKCIPHER,
 	.tfmsize = offsetof(struct crypto_akcipher, base),
 };
+EXPORT_SYMBOL_GPL(crypto_akcipher_type);
 
 struct crypto_akcipher *crypto_alloc_akcipher(const char *alg_name, u32 type,
 					      u32 mask)
diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
index c9fe145..1089f20 100644
--- a/include/crypto/algapi.h
+++ b/include/crypto/algapi.h
@@ -130,6 +130,7 @@ struct ablkcipher_walk {
 
 extern const struct crypto_type crypto_ablkcipher_type;
 extern const struct crypto_type crypto_blkcipher_type;
+extern const struct crypto_type crypto_akcipher_type;
 
 void crypto_mod_put(struct crypto_alg *alg);
 
diff --git a/include/crypto/internal/akcipher.h b/include/crypto/internal/akcipher.h
index 9a2bda1..706aa82 100644
--- a/include/crypto/internal/akcipher.h
+++ b/include/crypto/internal/akcipher.h
@@ -13,6 +13,17 @@
 #ifndef _CRYPTO_AKCIPHER_INT_H
 #define _CRYPTO_AKCIPHER_INT_H
 #include <crypto/akcipher.h>
+#include <crypto/algapi.h>
+
+struct akcipher_instance {
+	union {
+		struct {
+			char head[offsetof(struct akcipher_alg, base)];
+			struct crypto_instance base;
+		} s;
+		struct akcipher_alg alg;
+	};
+};
 
 /*
  * Transform internal helpers.
@@ -57,4 +68,16 @@ int crypto_register_akcipher(struct akcipher_alg *alg);
  * @alg:	algorithm definition
  */
 void crypto_unregister_akcipher(struct akcipher_alg *alg);
+
+static inline struct crypto_instance *akcipher_crypto_instance(
+		struct akcipher_instance *inst)
+{
+	return container_of(&inst->alg.base, struct crypto_instance, alg);
+}
+
+static inline struct akcipher_instance *akcipher_instance(
+		struct crypto_instance *inst)
+{
+	return container_of(&inst->alg, struct akcipher_instance, alg.base);
+}
 #endif
-- 
2.1.4

[PATCH 4/4] crypto: RSA padding algorithm

[Andrew Zaborowski]

This patch adds PKCS#1 v1.5 standard RSA padding as a separate template.
This way an RSA cipher with padding can be obtained by instantiating
"pkcs1pad(rsa)".  The reason for adding this is that RSA is almost
never used without this padding (or OAEP) so it will be needed for
either certificate work in the kernel or the userspace, and I also hear
that it is likely implemented by hardware RSA in which case hardware
implementations of the whole of pkcs1pad(rsa) can be provided.

Signed-off-by: Andrew Zaborowski <andrew.zaborowski@intel.com>
---
v2: rename rsa-padding.c to rsa-pkcs1pad.c,
    use a memset instead of a loop,
    add a key size check in pkcs1pad_sign,
    add a general comment about pkcs1pad_verify
v3: rewrite the initialisation to avoid an obsolete and less flexible
    mechanism, now following the aead template initialisation.
---
 crypto/Makefile               |   1 +
 crypto/rsa-pkcs1pad.c         | 604 ++++++++++++++++++++++++++++++++++++++++++
 crypto/rsa.c                  |  16 +-
 include/crypto/internal/rsa.h |   2 +
 4 files changed, 622 insertions(+), 1 deletion(-)
 create mode 100644 crypto/rsa-pkcs1pad.c

diff --git a/crypto/Makefile b/crypto/Makefile
index f7aba92..2acdbbd 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -40,6 +40,7 @@ rsa_generic-y := rsapubkey-asn1.o
 rsa_generic-y += rsaprivkey-asn1.o
 rsa_generic-y += rsa.o
 rsa_generic-y += rsa_helper.o
+rsa_generic-y += rsa-pkcs1pad.o
 obj-$(CONFIG_CRYPTO_RSA) += rsa_generic.o
 
 cryptomgr-y := algboss.o testmgr.o
diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c
new file mode 100644
index 0000000..8ee22a2
--- /dev/null
+++ b/crypto/rsa-pkcs1pad.c
@@ -0,0 +1,604 @@
+/*
+ * RSA padding templates.
+ *
+ * Copyright (c) 2015  Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/akcipher.h>
+#include <crypto/internal/akcipher.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/random.h>
+
+struct pkcs1pad_ctx {
+	struct crypto_akcipher *child;
+
+	unsigned int key_size;
+};
+
+struct pkcs1pad_request {
+	struct akcipher_request child_req;
+
+	struct scatterlist in_sg[3], out_sg[2];
+	uint8_t *in_buf, *out_buf;
+};
+
+static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
+		unsigned int keylen)
+{
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	int err, size;
+
+	err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);
+
+	if (!err) {
+		/* Find out new modulus size from rsa implementation */
+		size = crypto_akcipher_maxsize(ctx->child);
+
+		ctx->key_size = size > 0 ? size : 0;
+		if (size <= 0)
+			err = size;
+	}
+
+	return err;
+}
+
+static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
+		unsigned int keylen)
+{
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	int err, size;
+
+	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
+
+	if (!err) {
+		/* Find out new modulus size from rsa implementation */
+		size = crypto_akcipher_maxsize(ctx->child);
+
+		ctx->key_size = size > 0 ? size : 0;
+		if (size <= 0)
+			err = size;
+	}
+
+	return err;
+}
+
+static int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
+{
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+
+	/*
+	 * The maximum destination buffer size for the encrypt/sign operations
+	 * will be the same as for RSA, even though it's smaller for
+	 * decrypt/verify.
+	 */
+
+	return ctx->key_size ?: -EINVAL;
+}
+
+static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
+		struct scatterlist *next)
+{
+	int nsegs = next ? 1 : 0;
+
+	if (offset_in_page(buf) + len <= PAGE_SIZE) {
+		nsegs += 1;
+		sg_init_table(sg, nsegs);
+		sg_set_buf(sg, buf, len);
+	} else {
+		nsegs += 2;
+		sg_init_table(sg, nsegs);
+		sg_set_buf(sg + 0, buf, PAGE_SIZE - offset_in_page(buf));
+		sg_set_buf(sg + 1, buf + PAGE_SIZE - offset_in_page(buf),
+				offset_in_page(buf) + len - PAGE_SIZE);
+	}
+
+	if (next)
+		sg_chain(sg, nsegs, next);
+}
+
+static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	uint8_t zeros[ctx->key_size - req_ctx->child_req.dst_len];
+
+	if (!err) {
+		if (req_ctx->child_req.dst_len < ctx->key_size) {
+			memset(zeros, 0, sizeof(zeros));
+			sg_copy_from_buffer(req->dst,
+					sg_nents_for_len(req->dst,
+						sizeof(zeros)),
+					zeros, sizeof(zeros));
+		}
+
+		sg_pcopy_from_buffer(req->dst,
+				sg_nents_for_len(req->dst, ctx->key_size),
+				req_ctx->out_buf, req_ctx->child_req.dst_len,
+				sizeof(zeros));
+	}
+	req->dst_len = ctx->key_size;
+
+	kfree(req_ctx->in_buf);
+	kzfree(req_ctx->out_buf);
+
+	return err;
+}
+
+static void pkcs1pad_encrypt_sign_complete_cb(
+		struct crypto_async_request *child_async_req, int err)
+{
+	struct akcipher_request *req = child_async_req->data;
+	struct crypto_async_request async_req;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	async_req.data = req->base.data;
+	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
+	async_req.flags = child_async_req->flags;
+	req->base.complete(&async_req,
+			pkcs1pad_encrypt_sign_complete(req, err));
+}
+
+static int pkcs1pad_encrypt(struct akcipher_request *req)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	int err;
+	unsigned int i, ps_end;
+
+	if (!ctx->key_size)
+		return -EINVAL;
+
+	if (req->src_len > ctx->key_size - 11)
+		return -EOVERFLOW;
+
+	if (req->dst_len < ctx->key_size) {
+		req->dst_len = ctx->key_size;
+		return -EOVERFLOW;
+	}
+
+	if (ctx->key_size > PAGE_SIZE)
+		return -ENOTSUPP;
+
+	/*
+	 * Replace both input and output to add the padding in the input and
+	 * the potential missing leading zeros in the output.
+	 */
+	req_ctx->child_req.src = req_ctx->in_sg;
+	req_ctx->child_req.src_len = ctx->key_size - 1;
+	req_ctx->child_req.dst = req_ctx->out_sg;
+	req_ctx->child_req.dst_len = ctx->key_size;
+
+	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
+			(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+			GFP_KERNEL : GFP_ATOMIC);
+	if (!req_ctx->in_buf)
+		return -ENOMEM;
+
+	ps_end = ctx->key_size - req->src_len - 2;
+	req_ctx->in_buf[0] = 0x02;
+	for (i = 1; i < ps_end; i++)
+		req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
+	req_ctx->in_buf[ps_end] = 0x00;
+
+	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
+			ctx->key_size - 1 - req->src_len, req->src);
+
+	req_ctx->out_buf = kmalloc(ctx->key_size,
+			(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+			GFP_KERNEL : GFP_ATOMIC);
+	if (!req_ctx->out_buf) {
+		kfree(req_ctx->in_buf);
+		return -ENOMEM;
+	}
+
+	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
+			ctx->key_size, NULL);
+
+	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
+	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
+			pkcs1pad_encrypt_sign_complete_cb, req);
+
+	err = crypto_akcipher_encrypt(&req_ctx->child_req);
+	if (err != -EINPROGRESS && err != -EBUSY)
+		return pkcs1pad_encrypt_sign_complete(req, err);
+
+	return err;
+}
+
+static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	unsigned int pos;
+
+	if (err == -EOVERFLOW)
+		/* Decrypted value had no leading 0 byte */
+		err = -EINVAL;
+
+	if (err)
+		goto done;
+
+	if (req_ctx->child_req.dst_len != ctx->key_size - 1) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	if (req_ctx->out_buf[0] != 0x02) {
+		err = -EINVAL;
+		goto done;
+	}
+	for (pos = 1; pos < req_ctx->child_req.dst_len; pos++)
+		if (req_ctx->out_buf[pos] == 0x00)
+			break;
+	if (pos < 9 || pos == req_ctx->child_req.dst_len) {
+		err = -EINVAL;
+		goto done;
+	}
+	pos++;
+
+	if (req->dst_len < req_ctx->child_req.dst_len - pos)
+		err = -EOVERFLOW;
+	req->dst_len = req_ctx->child_req.dst_len - pos;
+
+	if (!err)
+		sg_copy_from_buffer(req->dst,
+				sg_nents_for_len(req->dst, req->dst_len),
+				req_ctx->out_buf + pos, req->dst_len);
+
+done:
+	kzfree(req_ctx->out_buf);
+
+	return err;
+}
+
+static void pkcs1pad_decrypt_complete_cb(
+		struct crypto_async_request *child_async_req, int err)
+{
+	struct akcipher_request *req = child_async_req->data;
+	struct crypto_async_request async_req;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	async_req.data = req->base.data;
+	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
+	async_req.flags = child_async_req->flags;
+	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
+}
+
+static int pkcs1pad_decrypt(struct akcipher_request *req)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	int err;
+
+	if (!ctx->key_size || req->src_len != ctx->key_size)
+		return -EINVAL;
+
+	if (ctx->key_size > PAGE_SIZE)
+		return -ENOTSUPP;
+
+	/* Reuse input buffer, output to a new buffer */
+	req_ctx->child_req.src = req->src;
+	req_ctx->child_req.src_len = req->src_len;
+	req_ctx->child_req.dst = req_ctx->out_sg;
+	req_ctx->child_req.dst_len = ctx->key_size - 1;
+
+	req_ctx->out_buf = kmalloc(ctx->key_size - 1,
+			(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+			GFP_KERNEL : GFP_ATOMIC);
+	if (!req_ctx->out_buf)
+		return -ENOMEM;
+
+	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
+			ctx->key_size - 1, NULL);
+
+	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
+	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
+			pkcs1pad_decrypt_complete_cb, req);
+
+	err = crypto_akcipher_decrypt(&req_ctx->child_req);
+	if (err != -EINPROGRESS && err != -EBUSY)
+		return pkcs1pad_decrypt_complete(req, err);
+
+	return err;
+}
+
+static int pkcs1pad_sign(struct akcipher_request *req)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	int err;
+	unsigned int ps_end;
+
+	if (!ctx->key_size)
+		return -EINVAL;
+
+	if (req->src_len > ctx->key_size - 11)
+		return -EOVERFLOW;
+
+	if (req->dst_len < ctx->key_size) {
+		req->dst_len = ctx->key_size;
+		return -EOVERFLOW;
+	}
+
+	if (ctx->key_size > PAGE_SIZE)
+		return -ENOTSUPP;
+
+	/*
+	 * Replace both input and output to add the padding in the input and
+	 * the potential missing leading zeros in the output.
+	 */
+	req_ctx->child_req.src = req_ctx->in_sg;
+	req_ctx->child_req.src_len = ctx->key_size - 1;
+	req_ctx->child_req.dst = req_ctx->out_sg;
+	req_ctx->child_req.dst_len = ctx->key_size;
+
+	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
+			(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+			GFP_KERNEL : GFP_ATOMIC);
+	if (!req_ctx->in_buf)
+		return -ENOMEM;
+
+	ps_end = ctx->key_size - req->src_len - 2;
+	req_ctx->in_buf[0] = 0x01;
+	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
+	req_ctx->in_buf[ps_end] = 0x00;
+
+	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
+			ctx->key_size - 1 - req->src_len, req->src);
+
+	req_ctx->out_buf = kmalloc(ctx->key_size,
+			(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+			GFP_KERNEL : GFP_ATOMIC);
+	if (!req_ctx->out_buf) {
+		kfree(req_ctx->in_buf);
+		return -ENOMEM;
+	}
+
+	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
+			ctx->key_size, NULL);
+
+	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
+	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
+			pkcs1pad_encrypt_sign_complete_cb, req);
+
+	err = crypto_akcipher_sign(&req_ctx->child_req);
+	if (err != -EINPROGRESS && err != -EBUSY)
+		return pkcs1pad_encrypt_sign_complete(req, err);
+
+	return err;
+}
+
+static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	unsigned int pos;
+
+	if (err == -EOVERFLOW)
+		/* Decrypted value had no leading 0 byte */
+		err = -EINVAL;
+
+	if (err)
+		goto done;
+
+	if (req_ctx->child_req.dst_len != ctx->key_size - 1) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	if (req_ctx->out_buf[0] != 0x01) {
+		err = -EINVAL;
+		goto done;
+	}
+	for (pos = 1; pos < req_ctx->child_req.dst_len; pos++)
+		if (req_ctx->out_buf[pos] != 0xff)
+			break;
+	if (pos < 9 || pos == req_ctx->child_req.dst_len ||
+			req_ctx->out_buf[pos] != 0x00) {
+		err = -EINVAL;
+		goto done;
+	}
+	pos++;
+
+	if (req->dst_len < req_ctx->child_req.dst_len - pos)
+		err = -EOVERFLOW;
+	req->dst_len = req_ctx->child_req.dst_len - pos;
+
+	if (!err)
+		sg_copy_from_buffer(req->dst,
+				sg_nents_for_len(req->dst, req->dst_len),
+				req_ctx->out_buf + pos, req->dst_len);
+
+done:
+	kzfree(req_ctx->out_buf);
+
+	return err;
+}
+
+static void pkcs1pad_verify_complete_cb(
+		struct crypto_async_request *child_async_req, int err)
+{
+	struct akcipher_request *req = child_async_req->data;
+	struct crypto_async_request async_req;
+
+	if (err == -EINPROGRESS)
+		return;
+
+	async_req.data = req->base.data;
+	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
+	async_req.flags = child_async_req->flags;
+	req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
+}
+
+/*
+ * The verify operation is here for completeness similar to the verification
+ * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
+ * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
+ * retrieve the DigestInfo from a signature, instead the user is expected
+ * to call the sign operation to generate the expected signature and compare
+ * signatures instead of the message-digests.
+ */
+static int pkcs1pad_verify(struct akcipher_request *req)
+{
+	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
+	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
+	int err;
+
+	if (!ctx->key_size || req->src_len != ctx->key_size)
+		return -EINVAL;
+
+	if (ctx->key_size > PAGE_SIZE)
+		return -ENOTSUPP;
+
+	/* Reuse input buffer, output to a new buffer */
+	req_ctx->child_req.src = req->src;
+	req_ctx->child_req.src_len = req->src_len;
+	req_ctx->child_req.dst = req_ctx->out_sg;
+	req_ctx->child_req.dst_len = ctx->key_size - 1;
+
+	req_ctx->out_buf = kmalloc(ctx->key_size - 1,
+			(req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
+			GFP_KERNEL : GFP_ATOMIC);
+	if (!req_ctx->out_buf)
+		return -ENOMEM;
+
+	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
+			ctx->key_size - 1, NULL);
+
+	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
+	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
+			pkcs1pad_verify_complete_cb, req);
+
+	err = crypto_akcipher_verify(&req_ctx->child_req);
+	if (err != -EINPROGRESS && err != -EBUSY)
+		return pkcs1pad_verify_complete(req, err);
+
+	return err;
+}
+
+static int pkcs1pad_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_instance *inst = crypto_tfm_alg_instance(tfm);
+	struct pkcs1pad_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_akcipher *child_tfm;
+
+	child_tfm = crypto_spawn_tfm2(crypto_instance_ctx(inst));
+	if (IS_ERR(child_tfm))
+		return PTR_ERR(child_tfm);
+
+	ctx->child = child_tfm;
+
+	return 0;
+}
+
+static void pkcs1pad_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct pkcs1pad_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_akcipher(ctx->child);
+}
+
+static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
+{
+	struct akcipher_instance *inst;
+	struct crypto_spawn *spawn;
+	struct akcipher_alg *rsa_alg;
+	const char *rsa_alg_name;
+	int err;
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AKCIPHER);
+	if (err)
+		return err;
+
+	rsa_alg_name = crypto_attr_alg_name(tb[1]);
+	if (IS_ERR(rsa_alg_name))
+		return PTR_ERR(rsa_alg_name);
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
+	if (!inst)
+		return -ENOMEM;
+
+	spawn = crypto_instance_ctx(akcipher_crypto_instance(inst));
+	crypto_set_spawn(spawn, akcipher_crypto_instance(inst));
+	spawn->frontend = &crypto_akcipher_type;
+	err = crypto_grab_spawn(spawn, rsa_alg_name, 0,
+			spawn->frontend->maskset);
+	if (err)
+		goto out_free_inst;
+
+	rsa_alg = container_of(spawn->alg, struct akcipher_alg, base);
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.base.cra_name,
+				CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
+				rsa_alg->base.cra_name) >=
+			CRYPTO_MAX_ALG_NAME ||
+			snprintf(inst->alg.base.cra_driver_name,
+				CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
+				rsa_alg->base.cra_driver_name) >=
+			CRYPTO_MAX_ALG_NAME)
+		goto out_drop_alg;
+
+	inst->alg.base.cra_flags = CRYPTO_ALG_TYPE_AKCIPHER |
+		(rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC);
+	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
+	inst->alg.base.cra_type = spawn->frontend;
+
+	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
+	inst->alg.base.cra_init = pkcs1pad_init_tfm;
+	inst->alg.base.cra_exit = pkcs1pad_exit_tfm;
+
+	inst->alg.encrypt = pkcs1pad_encrypt;
+	inst->alg.decrypt = pkcs1pad_decrypt;
+	inst->alg.sign = pkcs1pad_sign;
+	inst->alg.verify = pkcs1pad_verify;
+	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
+	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
+	inst->alg.max_size = pkcs1pad_get_max_size;
+	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
+
+	err = crypto_register_instance(tmpl, akcipher_crypto_instance(inst));
+	if (err)
+		goto out_drop_alg;
+
+	return 0;
+
+out_drop_alg:
+	crypto_drop_spawn(spawn);
+out_free_inst:
+	kfree(inst);
+	return err;
+}
+
+static void pkcs1pad_free(struct crypto_instance *inst)
+{
+	crypto_drop_spawn(crypto_instance_ctx(inst));
+	kfree(akcipher_instance(inst));
+}
+
+struct crypto_template rsa_pkcs1pad_tmpl = {
+	.name = "pkcs1pad",
+	.create = pkcs1pad_create,
+	.free = pkcs1pad_free,
+	.module = THIS_MODULE,
+};
diff --git a/crypto/rsa.c b/crypto/rsa.c
index 58aad69..77d737f 100644
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -13,6 +13,7 @@
 #include <crypto/internal/rsa.h>
 #include <crypto/internal/akcipher.h>
 #include <crypto/akcipher.h>
+#include <crypto/algapi.h>
 
 /*
  * RSAEP function [RFC3447 sec 5.1.1]
@@ -315,11 +316,24 @@ static struct akcipher_alg rsa = {
 
 static int rsa_init(void)
 {
-	return crypto_register_akcipher(&rsa);
+	int err;
+
+	err = crypto_register_akcipher(&rsa);
+	if (err)
+		return err;
+
+	err = crypto_register_template(&rsa_pkcs1pad_tmpl);
+	if (err) {
+		crypto_unregister_akcipher(&rsa);
+		return err;
+	}
+
+	return 0;
 }
 
 static void rsa_exit(void)
 {
+	crypto_unregister_template(&rsa_pkcs1pad_tmpl);
 	crypto_unregister_akcipher(&rsa);
 }
 
diff --git a/include/crypto/internal/rsa.h b/include/crypto/internal/rsa.h
index f997e2d..c7585bd 100644
--- a/include/crypto/internal/rsa.h
+++ b/include/crypto/internal/rsa.h
@@ -27,4 +27,6 @@ int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
 		       unsigned int key_len);
 
 void rsa_free_key(struct rsa_key *rsa_key);
+
+extern struct crypto_template rsa_pkcs1pad_tmpl;
 #endif
-- 
2.1.4

Re: [PATCH v3 3/4] crypto: akcipher: add akcipher declarations useful for templates.

[Herbert Xu]

Andrew Zaborowski <andrew.zaborowski@intel.com> wrote:
> Expose crypto_akcipher_type like other crypto types are exposed to be
> used from outside akcipher.c.  Add a struct akcipher_instance similar to
> aead_instance with just the right size for an akcipher template
> instance, and two macros for converting to/from crypto_instance.

You're still doing some things in the old way.  With new templates,
you shouldn't need to export the crypto type at all.  Please look
at how AEAD does it.

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: [PATCH v3 3/4] crypto: akcipher: add akcipher declarations useful for templates.

[Andrzej Zaborowski]

On 24 November 2015 at 10:54, Herbert Xu <herbert@gondor.apana.org.au> wrote:
> Andrew Zaborowski <andrew.zaborowski@intel.com> wrote:
>> Expose crypto_akcipher_type like other crypto types are exposed to be
>> used from outside akcipher.c.  Add a struct akcipher_instance similar to
>> aead_instance with just the right size for an akcipher template
>> instance, and two macros for converting to/from crypto_instance.
>
> You're still doing some things in the old way.  With new templates,
> you shouldn't need to export the crypto type at all.  Please look
> at how AEAD does it.

It doesn't need to export crypto_aead_type but instead needs to export
crypto_aead_grab and aead_register_instance.  I'll add those for
akcipher and resend then.  Would there be any point defining a
crypto_akcipher_spawn following the AEAD pattern?

Best regards

Re: [PATCH v3 3/4] crypto: akcipher: add akcipher declarations useful for templates.

[Herbert Xu]

On Tue, Nov 24, 2015 at 09:54:57PM +0100, Andrzej Zaborowski wrote:
>
> It doesn't need to export crypto_aead_type but instead needs to export
> crypto_aead_grab and aead_register_instance.  I'll add those for
> akcipher and resend then.  Would there be any point defining a
> crypto_akcipher_spawn following the AEAD pattern?

Well if you need to spawn an akcipher (which I presume you do) then
yes you should define it.

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