[PATCH v2] crypto: caam/qi2 - fix chacha20 data size error

["Horia Geantă" <horia.geanta@nxp.com>]

HW generates a Data Size error for chacha20 requests that are not
a multiple of 64B, since algorithm state (AS) does not have
the FINAL bit set.

Since updating req->iv (for chaining) is not required,
modify skcipher descriptors to set the FINAL bit for chacha20.

[Note that for skcipher decryption we know that ctx1_iv_off is 0,
which allows for an optimization by not checking algorithm type,
since append_dec_op1() sets FINAL bit for all algorithms except AES.]

Also drop the descriptor operations that save the IV.
However, in order to keep code logic simple, things like
S/G tables generation etc. are not touched.

Cc: <stable@vger.kernel.org> # v5.3+
Fixes: 334d37c9e263 ("crypto: caam - update IV using HW support")
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
---
 drivers/crypto/caam/caamalg_desc.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/crypto/caam/caamalg_desc.c b/drivers/crypto/caam/caamalg_desc.c
index aa9ccca67045..6171a8118b5a 100644
--- a/drivers/crypto/caam/caamalg_desc.c
+++ b/drivers/crypto/caam/caamalg_desc.c
@@ -1379,6 +1379,9 @@ void cnstr_shdsc_skcipher_encap(u32 * const desc, struct alginfo *cdata,
 				const u32 ctx1_iv_off)
 {
 	u32 *key_jump_cmd;
+	u32 options = cdata->algtype | OP_ALG_AS_INIT | OP_ALG_ENCRYPT;
+	bool is_chacha20 = ((cdata->algtype & OP_ALG_ALGSEL_MASK) ==
+			    OP_ALG_ALGSEL_CHACHA20);
 
 	init_sh_desc(desc, HDR_SHARE_SERIAL | HDR_SAVECTX);
 	/* Skip if already shared */
@@ -1417,14 +1420,15 @@ void cnstr_shdsc_skcipher_encap(u32 * const desc, struct alginfo *cdata,
 				      LDST_OFFSET_SHIFT));
 
 	/* Load operation */
-	append_operation(desc, cdata->algtype | OP_ALG_AS_INIT |
-			 OP_ALG_ENCRYPT);
+	if (is_chacha20)
+		options |= OP_ALG_AS_FINALIZE;
+	append_operation(desc, options);
 
 	/* Perform operation */
 	skcipher_append_src_dst(desc);
 
 	/* Store IV */
-	if (ivsize)
+	if (!is_chacha20 && ivsize)
 		append_seq_store(desc, ivsize, LDST_SRCDST_BYTE_CONTEXT |
 				 LDST_CLASS_1_CCB | (ctx1_iv_off <<
 				 LDST_OFFSET_SHIFT));
@@ -1451,6 +1455,8 @@ void cnstr_shdsc_skcipher_decap(u32 * const desc, struct alginfo *cdata,
 				const u32 ctx1_iv_off)
 {
 	u32 *key_jump_cmd;
+	bool is_chacha20 = ((cdata->algtype & OP_ALG_ALGSEL_MASK) ==
+			    OP_ALG_ALGSEL_CHACHA20);
 
 	init_sh_desc(desc, HDR_SHARE_SERIAL | HDR_SAVECTX);
 	/* Skip if already shared */
@@ -1499,7 +1505,7 @@ void cnstr_shdsc_skcipher_decap(u32 * const desc, struct alginfo *cdata,
 	skcipher_append_src_dst(desc);
 
 	/* Store IV */
-	if (ivsize)
+	if (!is_chacha20 && ivsize)
 		append_seq_store(desc, ivsize, LDST_SRCDST_BYTE_CONTEXT |
 				 LDST_CLASS_1_CCB | (ctx1_iv_off <<
 				 LDST_OFFSET_SHIFT));
-- 
2.17.1