s390/crypto: add s390 platform specific aes gcm support.

This patch introduces gcm(aes) support into the aes_s390 kernel module.
Signed-off-by: Patrick Steuer <patrick.steuer@de.ibm.com>
Signed-off-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/crypto/aes_s390.c

@@ -4,9 +4,11 @@
  * s390 implementation of the AES Cipher Algorithm.
  *
  * s390 Version:
- *   Copyright IBM Corp. 2005, 2007
+ *   Copyright IBM Corp. 2005, 2017
  *   Author(s): Jan Glauber (jang@de.ibm.com)
  *		Sebastian Siewior (sebastian@breakpoint.cc> SW-Fallback
+ *		Patrick Steuer <patrick.steuer@de.ibm.com>
+ *		Harald Freudenberger <freude@de.ibm.com>
  *
  * Derived from "crypto/aes_generic.c"
  *
@@ -22,20 +24,25 @@
 
 #include <crypto/aes.h>
 #include <crypto/algapi.h>
+#include <crypto/ghash.h>
+#include <crypto/internal/aead.h>
 #include <crypto/internal/skcipher.h>
+#include <crypto/scatterwalk.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/cpufeature.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/fips.h>
+#include <linux/string.h>
 #include <crypto/xts.h>
 #include <asm/cpacf.h>
 
 static u8 *ctrblk;
 static DEFINE_SPINLOCK(ctrblk_lock);
 
-static cpacf_mask_t km_functions, kmc_functions, kmctr_functions;
+static cpacf_mask_t km_functions, kmc_functions, kmctr_functions,
+		    kma_functions;
 
 struct s390_aes_ctx {
 	u8 key[AES_MAX_KEY_SIZE];
@@ -55,6 +62,17 @@ struct s390_xts_ctx {
 	struct crypto_skcipher *fallback;
 };
 
+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;
+	u8 *ptr;
+	unsigned int nbytes;
+};
+
 static int setkey_fallback_cip(struct crypto_tfm *tfm, const u8 *in_key,
 		unsigned int key_len)
 {
@@ -771,6 +789,267 @@ static struct crypto_alg ctr_aes_alg = {
 	}
 };
 
+static int gcm_aes_setkey(struct crypto_aead *tfm, const u8 *key,
+			  unsigned int keylen)
+{
+	struct s390_aes_ctx *ctx = crypto_aead_ctx(tfm);
+
+	switch (keylen) {
+	case AES_KEYSIZE_128:
+		ctx->fc = CPACF_KMA_GCM_AES_128;
+		break;
+	case AES_KEYSIZE_192:
+		ctx->fc = CPACF_KMA_GCM_AES_192;
+		break;
+	case AES_KEYSIZE_256:
+		ctx->fc = CPACF_KMA_GCM_AES_256;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	memcpy(ctx->key, key, keylen);
+	ctx->key_len = keylen;
+	return 0;
+}
+
+static int gcm_aes_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
+{
+	switch (authsize) {
+	case 4:
+	case 8:
+	case 12:
+	case 13:
+	case 14:
+	case 15:
+	case 16:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void gcm_sg_walk_start(struct gcm_sg_walk *gw, struct scatterlist *sg,
+			      unsigned int len)
+{
+	memset(gw, 0, sizeof(*gw));
+	gw->walk_bytes_remain = len;
+	scatterwalk_start(&gw->walk, sg);
+}
+
+static int gcm_sg_walk_go(struct gcm_sg_walk *gw, unsigned int minbytesneeded)
+{
+	int n;
+
+	/* minbytesneeded <= AES_BLOCK_SIZE */
+	if (gw->buf_bytes && gw->buf_bytes >= minbytesneeded) {
+		gw->ptr = gw->buf;
+		gw->nbytes = gw->buf_bytes;
+		goto out;
+	}
+
+	if (gw->walk_bytes_remain == 0) {
+		gw->ptr = NULL;
+		gw->nbytes = 0;
+		goto out;
+	}
+
+	gw->walk_bytes = scatterwalk_clamp(&gw->walk, gw->walk_bytes_remain);
+	if (!gw->walk_bytes) {
+		scatterwalk_start(&gw->walk, sg_next(gw->walk.sg));
+		gw->walk_bytes = scatterwalk_clamp(&gw->walk,
+						   gw->walk_bytes_remain);
+	}
+	gw->walk_ptr = scatterwalk_map(&gw->walk);
+
+	if (!gw->buf_bytes && gw->walk_bytes >= minbytesneeded) {
+		gw->ptr = gw->walk_ptr;
+		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);
+		gw->buf_bytes += n;
+		gw->walk_bytes_remain -= n;
+		scatterwalk_unmap(&gw->walk);
+		scatterwalk_advance(&gw->walk, n);
+		scatterwalk_done(&gw->walk, 0, gw->walk_bytes_remain);
+
+		if (gw->buf_bytes >= minbytesneeded) {
+			gw->ptr = gw->buf;
+			gw->nbytes = gw->buf_bytes;
+			goto out;
+		}
+
+		gw->walk_bytes = scatterwalk_clamp(&gw->walk,
+						   gw->walk_bytes_remain);
+		if (!gw->walk_bytes) {
+			scatterwalk_start(&gw->walk, sg_next(gw->walk.sg));
+			gw->walk_bytes = scatterwalk_clamp(&gw->walk,
+							gw->walk_bytes_remain);
+		}
+		gw->walk_ptr = scatterwalk_map(&gw->walk);
+	}
+
+out:
+	return gw->nbytes;
+}
+
+static void gcm_sg_walk_done(struct gcm_sg_walk *gw, unsigned int bytesdone)
+{
+	int n;
+
+	if (gw->ptr == NULL)
+		return;
+
+	if (gw->ptr == gw->buf) {
+		n = gw->buf_bytes - bytesdone;
+		if (n > 0) {
+			memmove(gw->buf, gw->buf + bytesdone, n);
+			gw->buf_bytes -= n;
+		} else
+			gw->buf_bytes = 0;
+	} else {
+		gw->walk_bytes_remain -= bytesdone;
+		scatterwalk_unmap(&gw->walk);
+		scatterwalk_advance(&gw->walk, bytesdone);
+		scatterwalk_done(&gw->walk, 0, gw->walk_bytes_remain);
+	}
+}
+
+static int gcm_aes_crypt(struct aead_request *req, unsigned int flags)
+{
+	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
+	struct s390_aes_ctx *ctx = crypto_aead_ctx(tfm);
+	unsigned int ivsize = crypto_aead_ivsize(tfm);
+	unsigned int taglen = crypto_aead_authsize(tfm);
+	unsigned int aadlen = req->assoclen;
+	unsigned int pclen = req->cryptlen;
+	int ret = 0;
+
+	unsigned int len, in_bytes, out_bytes,
+		     min_bytes, bytes, aad_bytes, pc_bytes;
+	struct gcm_sg_walk gw_in, gw_out;
+	u8 tag[GHASH_DIGEST_SIZE];
+
+	struct {
+		u32 _[3];		/* reserved */
+		u32 cv;			/* Counter Value */
+		u8 t[GHASH_DIGEST_SIZE];/* Tag */
+		u8 h[AES_BLOCK_SIZE];	/* Hash-subkey */
+		u64 taadl;		/* Total AAD Length */
+		u64 tpcl;		/* Total Plain-/Cipher-text Length */
+		u8 j0[GHASH_BLOCK_SIZE];/* initial counter value */
+		u8 k[AES_MAX_KEY_SIZE];	/* Key */
+	} param;
+
+	/*
+	 * encrypt
+	 *   req->src: aad||plaintext
+	 *   req->dst: aad||ciphertext||tag
+	 * decrypt
+	 *   req->src: aad||ciphertext||tag
+	 *   req->dst: aad||plaintext, return 0 or -EBADMSG
+	 * aad, plaintext and ciphertext may be empty.
+	 */
+	if (flags & CPACF_DECRYPT)
+		pclen -= taglen;
+	len = aadlen + pclen;
+
+	memset(&param, 0, sizeof(param));
+	param.cv = 1;
+	param.taadl = aadlen * 8;
+	param.tpcl = pclen * 8;
+	memcpy(param.j0, req->iv, ivsize);
+	*(u32 *)(param.j0 + ivsize) = 1;
+	memcpy(param.k, ctx->key, ctx->key_len);
+
+	gcm_sg_walk_start(&gw_in, req->src, len);
+	gcm_sg_walk_start(&gw_out, req->dst, len);
+
+	do {
+		min_bytes = min_t(unsigned int,
+				  aadlen > 0 ? aadlen : pclen, AES_BLOCK_SIZE);
+		in_bytes = gcm_sg_walk_go(&gw_in, min_bytes);
+		out_bytes = gcm_sg_walk_go(&gw_out, min_bytes);
+		bytes = min(in_bytes, out_bytes);
+
+		if (aadlen + pclen <= bytes) {
+			aad_bytes = aadlen;
+			pc_bytes = pclen;
+			flags |= CPACF_KMA_LAAD | CPACF_KMA_LPC;
+		} else {
+			if (aadlen <= bytes) {
+				aad_bytes = aadlen;
+				pc_bytes = (bytes - aadlen) &
+					   ~(AES_BLOCK_SIZE - 1);
+				flags |= CPACF_KMA_LAAD;
+			} else {
+				aad_bytes = bytes & ~(AES_BLOCK_SIZE - 1);
+				pc_bytes = 0;
+			}
+		}
+
+		if (aad_bytes > 0)
+			memcpy(gw_out.ptr, gw_in.ptr, aad_bytes);
+
+		cpacf_kma(ctx->fc | flags, &param,
+			  gw_out.ptr + aad_bytes,
+			  gw_in.ptr + aad_bytes, pc_bytes,
+			  gw_in.ptr, aad_bytes);
+
+		gcm_sg_walk_done(&gw_in, aad_bytes + pc_bytes);
+		gcm_sg_walk_done(&gw_out, aad_bytes + pc_bytes);
+		aadlen -= aad_bytes;
+		pclen -= pc_bytes;
+	} while (aadlen + pclen > 0);
+
+	if (flags & CPACF_DECRYPT) {
+		scatterwalk_map_and_copy(tag, req->src, len, taglen, 0);
+		if (crypto_memneq(tag, param.t, taglen))
+			ret = -EBADMSG;
+	} else
+		scatterwalk_map_and_copy(param.t, req->dst, len, taglen, 1);
+
+	memzero_explicit(&param, sizeof(param));
+	return ret;
+}
+
+static int gcm_aes_encrypt(struct aead_request *req)
+{
+	return gcm_aes_crypt(req, CPACF_ENCRYPT);
+}
+
+static int gcm_aes_decrypt(struct aead_request *req)
+{
+	return gcm_aes_crypt(req, CPACF_DECRYPT);
+}
+
+static struct aead_alg gcm_aes_aead = {
+	.setkey			= gcm_aes_setkey,
+	.setauthsize		= gcm_aes_setauthsize,
+	.encrypt		= gcm_aes_encrypt,
+	.decrypt		= gcm_aes_decrypt,
+
+	.ivsize			= GHASH_BLOCK_SIZE - sizeof(u32),
+	.maxauthsize		= GHASH_DIGEST_SIZE,
+	.chunksize		= AES_BLOCK_SIZE,
+
+	.base			= {
+		.cra_flags		= CRYPTO_ALG_TYPE_AEAD,
+		.cra_blocksize		= 1,
+		.cra_ctxsize		= sizeof(struct s390_aes_ctx),
+		.cra_priority		= 900,
+		.cra_name		= "gcm(aes)",
+		.cra_driver_name	= "gcm-aes-s390",
+		.cra_module		= THIS_MODULE,
+	},
+};
+
 static struct crypto_alg *aes_s390_algs_ptr[5];
 static int aes_s390_algs_num;
 
@@ -790,16 +1069,19 @@ static void aes_s390_fini(void)
 		crypto_unregister_alg(aes_s390_algs_ptr[aes_s390_algs_num]);
 	if (ctrblk)
 		free_page((unsigned long) ctrblk);
+
+	crypto_unregister_aead(&gcm_aes_aead);
 }
 
 static int __init aes_s390_init(void)
 {
 	int ret;
 
-	/* Query available functions for KM, KMC and KMCTR */
+	/* Query available functions for KM, KMC, KMCTR and KMA */
 	cpacf_query(CPACF_KM, &km_functions);
 	cpacf_query(CPACF_KMC, &kmc_functions);
 	cpacf_query(CPACF_KMCTR, &kmctr_functions);
+	cpacf_query(CPACF_KMA, &kma_functions);
 
 	if (cpacf_test_func(&km_functions, CPACF_KM_AES_128) ||
 	    cpacf_test_func(&km_functions, CPACF_KM_AES_192) ||
@@ -840,6 +1122,14 @@ static int __init aes_s390_init(void)
 			goto out_err;
 	}
 
+	if (cpacf_test_func(&kma_functions, CPACF_KMA_GCM_AES_128) ||
+	    cpacf_test_func(&kma_functions, CPACF_KMA_GCM_AES_192) ||
+	    cpacf_test_func(&kma_functions, CPACF_KMA_GCM_AES_256)) {
+		ret = crypto_register_aead(&gcm_aes_aead);
+		if (ret)
+			goto out_err;
+	}
+
 	return 0;
 out_err:
 	aes_s390_fini();