Subject: [PATCH] Revert "mac80211: aes-cmac: switch to shash CMAC driver"
From: Felix Fietkau <[email-masked]>
Date: Sat, 7 Oct 2017 09:37:28 +0200

This reverts commit 26717828b75dd5c46e97f7f4a9b937d038bb2852.
Reduces mac80211 dependencies for LEDE

Signed-off-by: Felix Fietkau <[email-masked]>
---

--- a/net/mac80211/aes_cmac.c
+++ b/net/mac80211/aes_cmac.c
@@ -19,67 +19,151 @@
 #define CMAC_TLEN_256 16 /* CMAC TLen = 128 bits (16 octets) */
 #define AAD_LEN 20
 
-static const u8 zero[CMAC_TLEN_256];
 
-void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
+void gf_mulx(u8 *pad)
+{
+	int i, carry;
+
+	carry = pad[0] & 0x80;
+	for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
+		pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
+	pad[AES_BLOCK_SIZE - 1] <<= 1;
+	if (carry)
+		pad[AES_BLOCK_SIZE - 1] ^= 0x87;
+}
+
+void aes_cmac_vector(struct crypto_cipher *tfm, size_t num_elem,
+		     const u8 *addr[], const size_t *len, u8 *mac,
+		     size_t mac_len)
+{
+	u8 cbc[AES_BLOCK_SIZE], pad[AES_BLOCK_SIZE];
+	const u8 *pos, *end;
+	size_t i, e, left, total_len;
+
+	memset(cbc, 0, AES_BLOCK_SIZE);
+
+	total_len = 0;
+	for (e = 0; e < num_elem; e++)
+		total_len += len[e];
+	left = total_len;
+
+	e = 0;
+	pos = addr[0];
+	end = pos + len[0];
+
+	while (left >= AES_BLOCK_SIZE) {
+		for (i = 0; i < AES_BLOCK_SIZE; i++) {
+			cbc[i] ^= *pos++;
+			if (pos >= end) {
+				e++;
+				pos = addr[e];
+				end = pos + len[e];
+			}
+		}
+		if (left > AES_BLOCK_SIZE)
+			crypto_cipher_encrypt_one(tfm, cbc, cbc);
+		left -= AES_BLOCK_SIZE;
+	}
+
+	memset(pad, 0, AES_BLOCK_SIZE);
+	crypto_cipher_encrypt_one(tfm, pad, pad);
+	gf_mulx(pad);
+
+	if (left || total_len == 0) {
+		for (i = 0; i < left; i++) {
+			cbc[i] ^= *pos++;
+			if (pos >= end) {
+				e++;
+				pos = addr[e];
+				end = pos + len[e];
+			}
+		}
+		cbc[left] ^= 0x80;
+		gf_mulx(pad);
+	}
+
+	for (i = 0; i < AES_BLOCK_SIZE; i++)
+		pad[i] ^= cbc[i];
+	crypto_cipher_encrypt_one(tfm, pad, pad);
+	memcpy(mac, pad, mac_len);
+}
+
+
+void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,
 			const u8 *data, size_t data_len, u8 *mic)
 {
-	SHASH_DESC_ON_STACK(desc, tfm);
-	u8 out[AES_BLOCK_SIZE];
+	const u8 *addr[4];
+	size_t len[4];
+	u8 zero[CMAC_TLEN];
 	const __le16 *fc;
 
-	desc->tfm = tfm;
-
-	crypto_shash_init(desc);
-	crypto_shash_update(desc, aad, AAD_LEN);
+	memset(zero, 0, CMAC_TLEN);
+	addr[0] = aad;
+	len[0] = AAD_LEN;
 	fc = (const __le16 *)aad;
 	if (ieee80211_is_beacon(*fc)) {
 		/* mask Timestamp field to zero */
-		crypto_shash_update(desc, zero, 8);
-		crypto_shash_update(desc, data + 8, data_len - 8 - CMAC_TLEN);
+		addr[1] = zero;
+		len[1] = 8;
+		addr[2] = data + 8;
+		len[2] = data_len - 8 - CMAC_TLEN;
+		addr[3] = zero;
+		len[3] = CMAC_TLEN;
+		aes_cmac_vector(tfm, 4, addr, len, mic, CMAC_TLEN);
 	} else {
-		crypto_shash_update(desc, data, data_len - CMAC_TLEN);
+		addr[1] = data;
+		len[1] = data_len - CMAC_TLEN;
+		addr[2] = zero;
+		len[2] = CMAC_TLEN;
+		aes_cmac_vector(tfm, 3, addr, len, mic, CMAC_TLEN);
 	}
-	crypto_shash_finup(desc, zero, CMAC_TLEN, out);
-
-	memcpy(mic, out, CMAC_TLEN);
 }
 
-void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
+void ieee80211_aes_cmac_256(struct crypto_cipher *tfm, const u8 *aad,
 			    const u8 *data, size_t data_len, u8 *mic)
 {
-	SHASH_DESC_ON_STACK(desc, tfm);
+	const u8 *addr[4];
+	size_t len[4];
+	u8 zero[CMAC_TLEN_256];
 	const __le16 *fc;
 
-	desc->tfm = tfm;
-
-	crypto_shash_init(desc);
-	crypto_shash_update(desc, aad, AAD_LEN);
+	memset(zero, 0, CMAC_TLEN_256);
+	addr[0] = aad;
+	len[0] = AAD_LEN;
+	addr[1] = data;
 	fc = (const __le16 *)aad;
 	if (ieee80211_is_beacon(*fc)) {
 		/* mask Timestamp field to zero */
-		crypto_shash_update(desc, zero, 8);
-		crypto_shash_update(desc, data + 8,
-				    data_len - 8 - CMAC_TLEN_256);
+		addr[1] = zero;
+		len[1] = 8;
+		addr[2] = data + 8;
+		len[2] = data_len - 8 - CMAC_TLEN_256;
+		addr[3] = zero;
+		len[3] = CMAC_TLEN_256;
+		aes_cmac_vector(tfm, 4, addr, len, mic, CMAC_TLEN_256);
 	} else {
-		crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
+		addr[1] = data;
+		len[1] = data_len - CMAC_TLEN_256;
+		addr[2] = zero;
+		len[2] = CMAC_TLEN_256;
+		aes_cmac_vector(tfm, 3, addr, len, mic, CMAC_TLEN_256);
 	}
-	crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
 }
 
-struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
-						  size_t key_len)
+struct crypto_cipher *ieee80211_aes_cmac_key_setup(const u8 key[],
+						   size_t key_len)
 {
-	struct crypto_shash *tfm;
+	struct crypto_cipher *tfm;
 
-	tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
+	tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
 	if (!IS_ERR(tfm))
-		crypto_shash_setkey(tfm, key, key_len);
+		crypto_cipher_setkey(tfm, key, key_len);
 
 	return tfm;
 }
 
-void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
+
+void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm)
 {
-	crypto_free_shash(tfm);
+	crypto_free_cipher(tfm);
 }
--- a/net/mac80211/aes_cmac.h
+++ b/net/mac80211/aes_cmac.h
@@ -7,14 +7,13 @@
 #define AES_CMAC_H
 
 #include <linux/crypto.h>
-#include <crypto/hash.h>
 
-struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
-						  size_t key_len);
-void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
+struct crypto_cipher *ieee80211_aes_cmac_key_setup(const u8 key[],
+						   size_t key_len);
+void ieee80211_aes_cmac(struct crypto_cipher *tfm, const u8 *aad,
 			const u8 *data, size_t data_len, u8 *mic);
-void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
+void ieee80211_aes_cmac_256(struct crypto_cipher *tfm, const u8 *aad,
 			    const u8 *data, size_t data_len, u8 *mic);
-void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm);
+void ieee80211_aes_cmac_key_free(struct crypto_cipher *tfm);
 
 #endif /* AES_CMAC_H */
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -94,7 +94,7 @@ struct ieee80211_key {
 		} ccmp;
 		struct {
 			u8 rx_pn[IEEE80211_CMAC_PN_LEN];
-			struct crypto_shash *tfm;
+			struct crypto_cipher *tfm;
 			u32 replays; /* dot11RSNAStatsCMACReplays */
 			u32 icverrors; /* dot11RSNAStatsCMACICVErrors */
 		} aes_cmac;