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Subject[PATCH 4.13 10/47] staging: ccree: save ciphertext for CTS IV
Date
4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gilad Ben-Yossef <gilad@benyossef.com>

commit 737aed947f9b5bd749a2684e13572ee99a1b8bae upstream.

The crypto API requires saving the last blocks of ciphertext
in req->info for use as IV for CTS mode. The ccree driver
was not doing this. This patch fixes that.

The bug was manifested with cts(cbc(aes)) mode in tcrypt tests.

Fixes: 302ef8ebb4b2 ("Add CryptoCell skcipher support")
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/ccree/ssi_cipher.c | 40 +++++++++++++++++++++++++++++++++----
1 file changed, 36 insertions(+), 4 deletions(-)

--- a/drivers/staging/ccree/ssi_cipher.c
+++ b/drivers/staging/ccree/ssi_cipher.c
@@ -23,6 +23,7 @@
#include <crypto/aes.h>
#include <crypto/ctr.h>
#include <crypto/des.h>
+#include <crypto/scatterwalk.h>

#include "ssi_config.h"
#include "ssi_driver.h"
@@ -716,6 +717,7 @@ static int ssi_blkcipher_complete(struct
{
int completion_error = 0;
u32 inflight_counter;
+ struct ablkcipher_request *req = (struct ablkcipher_request *)areq;

ssi_buffer_mgr_unmap_blkcipher_request(dev, req_ctx, ivsize, src, dst);

@@ -726,6 +728,22 @@ static int ssi_blkcipher_complete(struct
ctx_p->drvdata->inflight_counter--;

if (areq) {
+ /*
+ * The crypto API expects us to set the req->info to the last
+ * ciphertext block. For encrypt, simply copy from the result.
+ * For decrypt, we must copy from a saved buffer since this
+ * could be an in-place decryption operation and the src is
+ * lost by this point.
+ */
+ if (req_ctx->gen_ctx.op_type == DRV_CRYPTO_DIRECTION_DECRYPT) {
+ memcpy(req->info, req_ctx->backup_info, ivsize);
+ kfree(req_ctx->backup_info);
+ } else {
+ scatterwalk_map_and_copy(req->info, req->dst,
+ (req->nbytes - ivsize),
+ ivsize, 0);
+ }
+
ablkcipher_request_complete(areq, completion_error);
return 0;
}
@@ -759,11 +777,13 @@ static int ssi_blkcipher_process(
if (unlikely(validate_data_size(ctx_p, nbytes))) {
SSI_LOG_ERR("Unsupported data size %d.\n", nbytes);
crypto_tfm_set_flags(tfm, CRYPTO_TFM_RES_BAD_BLOCK_LEN);
- return -EINVAL;
+ rc = -EINVAL;
+ goto exit_process;
}
if (nbytes == 0) {
/* No data to process is valid */
- return 0;
+ rc = 0;
+ goto exit_process;
}
/*For CTS in case of data size aligned to 16 use CBC mode*/
if (((nbytes % AES_BLOCK_SIZE) == 0) && (ctx_p->cipher_mode == DRV_CIPHER_CBC_CTS)) {
@@ -842,6 +862,9 @@ exit_process:
if (cts_restore_flag != 0)
ctx_p->cipher_mode = DRV_CIPHER_CBC_CTS;

+ if (rc != -EINPROGRESS)
+ kfree(req_ctx->backup_info);
+
return rc;
}

@@ -884,7 +907,6 @@ static int ssi_ablkcipher_encrypt(struct
struct blkcipher_req_ctx *req_ctx = ablkcipher_request_ctx(req);
unsigned int ivsize = crypto_ablkcipher_ivsize(ablk_tfm);

- req_ctx->backup_info = req->info;
req_ctx->is_giv = false;

return ssi_blkcipher_process(tfm, req_ctx, req->dst, req->src, req->nbytes, req->info, ivsize, (void *)req, DRV_CRYPTO_DIRECTION_ENCRYPT);
@@ -897,8 +919,18 @@ static int ssi_ablkcipher_decrypt(struct
struct blkcipher_req_ctx *req_ctx = ablkcipher_request_ctx(req);
unsigned int ivsize = crypto_ablkcipher_ivsize(ablk_tfm);

- req_ctx->backup_info = req->info;
+ /*
+ * Allocate and save the last IV sized bytes of the source, which will
+ * be lost in case of in-place decryption and might be needed for CTS.
+ */
+ req_ctx->backup_info = kmalloc(ivsize, GFP_KERNEL);
+ if (!req_ctx->backup_info)
+ return -ENOMEM;
+
+ scatterwalk_map_and_copy(req_ctx->backup_info, req->src,
+ (req->nbytes - ivsize), ivsize, 0);
req_ctx->is_giv = false;
+
return ssi_blkcipher_process(tfm, req_ctx, req->dst, req->src, req->nbytes, req->info, ivsize, (void *)req, DRV_CRYPTO_DIRECTION_DECRYPT);
}


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