2 files changed, 40 insertions, 139 deletions

diff --git a/drivers/virt/coco/sev-guest/Kconfig b/drivers/virt/coco/sev-guest/Kconfig
index 1cffc72c41cb..0b772bd921d8 100644
--- a/drivers/virt/coco/sev-guest/Kconfig
+++ b/drivers/virt/coco/sev-guest/Kconfig
@@ -2,9 +2,7 @@ config SEV_GUEST
 	tristate "AMD SEV Guest driver"
 	default m
 	depends on AMD_MEM_ENCRYPT
-	select CRYPTO
-	select CRYPTO_AEAD2
-	select CRYPTO_GCM
+	select CRYPTO_LIB_AESGCM
 	select TSM_REPORTS
 	help
 	  SEV-SNP firmware provides the guest a mechanism to communicate with
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 89754b019be2..a33daff516ed 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -17,8 +17,7 @@
 #include <linux/set_memory.h>
 #include <linux/fs.h>
 #include <linux/tsm.h>
-#include <crypto/aead.h>
-#include <linux/scatterlist.h>
+#include <crypto/gcm.h>
 #include <linux/psp-sev.h>
 #include <linux/sockptr.h>
 #include <linux/cleanup.h>
@@ -31,26 +30,18 @@
 #include <asm/sev.h>
 
 #define DEVICE_NAME	"sev-guest"
-#define AAD_LEN		48
-#define MSG_HDR_VER	1
 
 #define SNP_REQ_MAX_RETRY_DURATION	(60*HZ)
 #define SNP_REQ_RETRY_DELAY		(2*HZ)
 
 #define SVSM_MAX_RETRIES		3
 
-struct snp_guest_crypto {
-	struct crypto_aead *tfm;
-	u8 *iv, *authtag;
-	int iv_len, a_len;
-};
-
 struct snp_guest_dev {
 	struct device *dev;
 	struct miscdevice misc;
 
 	void *certs_data;
-	struct snp_guest_crypto *crypto;
+	struct aesgcm_ctx *ctx;
 	/* request and response are in unencrypted memory */
 	struct snp_guest_msg *request, *response;
 
@@ -169,132 +160,31 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file)
 	return container_of(dev, struct snp_guest_dev, misc);
 }
 
-static struct snp_guest_crypto *init_crypto(struct snp_guest_dev *snp_dev, u8 *key, size_t keylen)
+static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
 {
-	struct snp_guest_crypto *crypto;
+	struct aesgcm_ctx *ctx;
 
-	crypto = kzalloc(sizeof(*crypto), GFP_KERNEL_ACCOUNT);
-	if (!crypto)
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
+	if (!ctx)
 		return NULL;
 
-	crypto->tfm = crypto_alloc_aead("gcm(aes)", 0, 0);
-	if (IS_ERR(crypto->tfm))
-		goto e_free;
-
-	if (crypto_aead_setkey(crypto->tfm, key, keylen))
-		goto e_free_crypto;
-
-	crypto->iv_len = crypto_aead_ivsize(crypto->tfm);
-	crypto->iv = kmalloc(crypto->iv_len, GFP_KERNEL_ACCOUNT);
-	if (!crypto->iv)
-		goto e_free_crypto;
-
-	if (crypto_aead_authsize(crypto->tfm) > MAX_AUTHTAG_LEN) {
-		if (crypto_aead_setauthsize(crypto->tfm, MAX_AUTHTAG_LEN)) {
-			dev_err(snp_dev->dev, "failed to set authsize to %d\n", MAX_AUTHTAG_LEN);
-			goto e_free_iv;
-		}
+	if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) {
+		pr_err("Crypto context initialization failed\n");
+		kfree(ctx);
+		return NULL;
 	}
 
-	crypto->a_len = crypto_aead_authsize(crypto->tfm);
-	crypto->authtag = kmalloc(crypto->a_len, GFP_KERNEL_ACCOUNT);
-	if (!crypto->authtag)
-		goto e_free_iv;
-
-	return crypto;
-
-e_free_iv:
-	kfree(crypto->iv);
-e_free_crypto:
-	crypto_free_aead(crypto->tfm);
-e_free:
-	kfree(crypto);
-
-	return NULL;
-}
-
-static void deinit_crypto(struct snp_guest_crypto *crypto)
-{
-	crypto_free_aead(crypto->tfm);
-	kfree(crypto->iv);
-	kfree(crypto->authtag);
-	kfree(crypto);
-}
-
-static int enc_dec_message(struct snp_guest_crypto *crypto, struct snp_guest_msg *msg,
-			   u8 *src_buf, u8 *dst_buf, size_t len, bool enc)
-{
-	struct snp_guest_msg_hdr *hdr = &msg->hdr;
-	struct scatterlist src[3], dst[3];
-	DECLARE_CRYPTO_WAIT(wait);
-	struct aead_request *req;
-	int ret;
-
-	req = aead_request_alloc(crypto->tfm, GFP_KERNEL);
-	if (!req)
-		return -ENOMEM;
-
-	/*
-	 * AEAD memory operations:
-	 * +------ AAD -------+------- DATA -----+---- AUTHTAG----+
-	 * |  msg header      |  plaintext       |  hdr->authtag  |
-	 * | bytes 30h - 5Fh  |    or            |                |
-	 * |                  |   cipher         |                |
-	 * +------------------+------------------+----------------+
-	 */
-	sg_init_table(src, 3);
-	sg_set_buf(&src[0], &hdr->algo, AAD_LEN);
-	sg_set_buf(&src[1], src_buf, hdr->msg_sz);
-	sg_set_buf(&src[2], hdr->authtag, crypto->a_len);
-
-	sg_init_table(dst, 3);
-	sg_set_buf(&dst[0], &hdr->algo, AAD_LEN);
-	sg_set_buf(&dst[1], dst_buf, hdr->msg_sz);
-	sg_set_buf(&dst[2], hdr->authtag, crypto->a_len);
-
-	aead_request_set_ad(req, AAD_LEN);
-	aead_request_set_tfm(req, crypto->tfm);
-	aead_request_set_callback(req, 0, crypto_req_done, &wait);
-
-	aead_request_set_crypt(req, src, dst, len, crypto->iv);
-	ret = crypto_wait_req(enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req), &wait);
-
-	aead_request_free(req);
-	return ret;
-}
-
-static int __enc_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg,
-			 void *plaintext, size_t len)
-{
-	struct snp_guest_crypto *crypto = snp_dev->crypto;
-	struct snp_guest_msg_hdr *hdr = &msg->hdr;
-
-	memset(crypto->iv, 0, crypto->iv_len);
-	memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno));
-
-	return enc_dec_message(crypto, msg, plaintext, msg->payload, len, true);
-}
-
-static int dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg,
-		       void *plaintext, size_t len)
-{
-	struct snp_guest_crypto *crypto = snp_dev->crypto;
-	struct snp_guest_msg_hdr *hdr = &msg->hdr;
-
-	/* Build IV with response buffer sequence number */
-	memset(crypto->iv, 0, crypto->iv_len);
-	memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno));
-
-	return enc_dec_message(crypto, msg, msg->payload, plaintext, len, false);
+	return ctx;
 }
 
 static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz)
 {
-	struct snp_guest_crypto *crypto = snp_dev->crypto;
 	struct snp_guest_msg *resp_msg = &snp_dev->secret_response;
 	struct snp_guest_msg *req_msg = &snp_dev->secret_request;
 	struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr;
 	struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr;
+	struct aesgcm_ctx *ctx = snp_dev->ctx;
+	u8 iv[GCM_AES_IV_SIZE] = {};
 
 	pr_debug("response [seqno %lld type %d version %d sz %d]\n",
 		 resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version,
@@ -316,11 +206,16 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload,
 	 * If the message size is greater than our buffer length then return
 	 * an error.
 	 */
-	if (unlikely((resp_msg_hdr->msg_sz + crypto->a_len) > sz))
+	if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > sz))
 		return -EBADMSG;
 
 	/* Decrypt the payload */
-	return dec_payload(snp_dev, resp_msg, payload, resp_msg_hdr->msg_sz + crypto->a_len);
+	memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno)));
+	if (!aesgcm_decrypt(ctx, payload, resp_msg->payload, resp_msg_hdr->msg_sz,
+			    &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag))
+		return -EBADMSG;
+
+	return 0;
 }
 
 static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type,
@@ -328,6 +223,8 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
 {
 	struct snp_guest_msg *msg = &snp_dev->secret_request;
 	struct snp_guest_msg_hdr *hdr = &msg->hdr;
+	struct aesgcm_ctx *ctx = snp_dev->ctx;
+	u8 iv[GCM_AES_IV_SIZE] = {};
 
 	memset(msg, 0, sizeof(*msg));
 
@@ -347,7 +244,14 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8
 	pr_debug("request [seqno %lld type %d version %d sz %d]\n",
 		 hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz);
 
-	return __enc_payload(snp_dev, msg, payload, sz);
+	if (WARN_ON((sz + ctx->authsize) > sizeof(msg->payload)))
+		return -EBADMSG;
+
+	memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno)));
+	aesgcm_encrypt(ctx, msg->payload, payload, sz, &hdr->algo, AAD_LEN,
+		       iv, hdr->authtag);
+
+	return 0;
 }
 
 static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
@@ -495,7 +399,6 @@ struct snp_req_resp {
 
 static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
-	struct snp_guest_crypto *crypto = snp_dev->crypto;
 	struct snp_report_req *report_req = &snp_dev->req.report;
 	struct snp_report_resp *report_resp;
 	int rc, resp_len;
@@ -513,7 +416,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 	 * response payload. Make sure that it has enough space to cover the
 	 * authtag.
 	 */
-	resp_len = sizeof(report_resp->data) + crypto->a_len;
+	resp_len = sizeof(report_resp->data) + snp_dev->ctx->authsize;
 	report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT);
 	if (!report_resp)
 		return -ENOMEM;
@@ -534,7 +437,6 @@ e_free:
 static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
 {
 	struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key;
-	struct snp_guest_crypto *crypto = snp_dev->crypto;
 	struct snp_derived_key_resp derived_key_resp = {0};
 	int rc, resp_len;
 	/* Response data is 64 bytes and max authsize for GCM is 16 bytes. */
@@ -550,7 +452,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
 	 * response payload. Make sure that it has enough space to cover the
 	 * authtag.
 	 */
-	resp_len = sizeof(derived_key_resp.data) + crypto->a_len;
+	resp_len = sizeof(derived_key_resp.data) + snp_dev->ctx->authsize;
 	if (sizeof(buf) < resp_len)
 		return -ENOMEM;
 
@@ -579,7 +481,6 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 
 {
 	struct snp_ext_report_req *report_req = &snp_dev->req.ext_report;
-	struct snp_guest_crypto *crypto = snp_dev->crypto;
 	struct snp_report_resp *report_resp;
 	int ret, npages = 0, resp_len;
 	sockptr_t certs_address;
@@ -622,7 +523,7 @@ cmd:
 	 * response payload. Make sure that it has enough space to cover the
 	 * authtag.
 	 */
-	resp_len = sizeof(report_resp->data) + crypto->a_len;
+	resp_len = sizeof(report_resp->data) + snp_dev->ctx->authsize;
 	report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT);
 	if (!report_resp)
 		return -ENOMEM;
@@ -1147,8 +1048,8 @@ static int __init sev_guest_probe(struct platform_device *pdev)
 		goto e_free_response;
 
 	ret = -EIO;
-	snp_dev->crypto = init_crypto(snp_dev, snp_dev->vmpck, VMPCK_KEY_LEN);
-	if (!snp_dev->crypto)
+	snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN);
+	if (!snp_dev->ctx)
 		goto e_free_cert_data;
 
 	misc = &snp_dev->misc;
@@ -1174,11 +1075,13 @@ static int __init sev_guest_probe(struct platform_device *pdev)
 
 	ret =  misc_register(misc);
 	if (ret)
-		goto e_free_cert_data;
+		goto e_free_ctx;
 
 	dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", vmpck_id);
 	return 0;
 
+e_free_ctx:
+	kfree(snp_dev->ctx);
 e_free_cert_data:
 	free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE);
 e_free_response:
@@ -1197,7 +1100,7 @@ static void __exit sev_guest_remove(struct platform_device *pdev)
 	free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE);
 	free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg));
 	free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg));
-	deinit_crypto(snp_dev->crypto);
+	kfree(snp_dev->ctx);
 	misc_deregister(&snp_dev->misc);
 }