crypto: ccp - Add support for valid authsize values less than 16

AES GCM encryption allows for authsize values of 4, 8, and 12-16 bytes.
Validate the requested authsize, and retain it to save in the request
context.

Fixes: 36cf515b9bbe2 ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
Cc: <[e-mail]>
Signed-off-by: Gary R Hook <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/ccp/ccp-crypto-aes-galois.c

···
 static int ccp_aes_gcm_setauthsize(struct crypto_aead *tfm,
 				   unsigned int authsize)
 {
+	switch (authsize) {
+	case 16:
+	case 15:
+	case 14:
+	case 13:
+	case 12:
+	case 8:
+	case 4:
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	return 0;
 }
 
···
 	memset(&rctx->cmd, 0, sizeof(rctx->cmd));
 	INIT_LIST_HEAD(&rctx->cmd.entry);
 	rctx->cmd.engine = CCP_ENGINE_AES;
+	rctx->cmd.u.aes.authsize = crypto_aead_authsize(tfm);
 	rctx->cmd.u.aes.type = ctx->u.aes.type;
 	rctx->cmd.u.aes.mode = ctx->u.aes.mode;
 	rctx->cmd.u.aes.action = encrypt;

drivers/crypto/ccp/ccp-ops.c

···
 
 	unsigned long long *final;
 	unsigned int dm_offset;
+	unsigned int authsize;
 	unsigned int jobid;
 	unsigned int ilen;
 	bool in_place = true; /* Default value */
···
 	if (!aes->key) /* Gotta have a key SGL */
 		return -EINVAL;
 
+	/* Zero defaults to 16 bytes, the maximum size */
+	authsize = aes->authsize ? aes->authsize : AES_BLOCK_SIZE;
+	switch (authsize) {
+	case 16:
+	case 15:
+	case 14:
+	case 13:
+	case 12:
+	case 8:
+	case 4:
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	/* First, decompose the source buffer into AAD & PT,
 	 * and the destination buffer into AAD, CT & tag, or
 	 * the input into CT & tag.
···
 		p_tag = scatterwalk_ffwd(sg_tag, p_outp, ilen);
 	} else {
 		/* Input length for decryption includes tag */
-		ilen = aes->src_len - AES_BLOCK_SIZE;
+		ilen = aes->src_len - authsize;
 		p_tag = scatterwalk_ffwd(sg_tag, p_inp, ilen);
 	}
 
···
 
 	if (aes->action == CCP_AES_ACTION_ENCRYPT) {
 		/* Put the ciphered tag after the ciphertext. */
-		ccp_get_dm_area(&final_wa, 0, p_tag, 0, AES_BLOCK_SIZE);
+		ccp_get_dm_area(&final_wa, 0, p_tag, 0, authsize);
 	} else {
 		/* Does this ciphered tag match the input? */
-		ret = ccp_init_dm_workarea(&tag, cmd_q, AES_BLOCK_SIZE,
+		ret = ccp_init_dm_workarea(&tag, cmd_q, authsize,
 					   DMA_BIDIRECTIONAL);
 		if (ret)
 			goto e_tag;
-		ret = ccp_set_dm_area(&tag, 0, p_tag, 0, AES_BLOCK_SIZE);
+		ret = ccp_set_dm_area(&tag, 0, p_tag, 0, authsize);
 		if (ret)
 			goto e_tag;
 
 		ret = crypto_memneq(tag.address, final_wa.address,
-				    AES_BLOCK_SIZE) ? -EBADMSG : 0;
+				    authsize) ? -EBADMSG : 0;
 		ccp_dm_free(&tag);
 	}
 

include/linux/ccp.h

···
 	enum ccp_aes_mode mode;
 	enum ccp_aes_action action;
 
+	u32 authsize;
+
 	struct scatterlist *key;
 	u32 key_len;		/* In bytes */