messages: increase header by 3 bytes for alignment

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

4 files changed, 22 insertions, 15 deletions

diff --git a/src/cookie.c b/src/cookie.c
index 21f287f..a2d1b22 100644
--- a/src/cookie.c
+++ b/src/cookie.c
@@ -163,7 +163,7 @@ void cookie_message_create(struct message_handshake_cookie *dst, struct sk_buff
 	u8 key[NOISE_SYMMETRIC_KEY_LEN];
 	u8 cookie[COOKIE_LEN];
 
-	dst->header.type = MESSAGE_HANDSHAKE_COOKIE;
+	dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE);
 	dst->receiver_index = index;
 	get_random_bytes(dst->salt, COOKIE_SALT_LEN);
 	blake2s(dst->salt, dst->salt, NULL, COOKIE_SALT_LEN, COOKIE_SALT_LEN, 0); /* Avoid directly transmitting RNG output. */
diff --git a/src/data.c b/src/data.c
index ff9fd66..f8d33c6 100644
--- a/src/data.c
+++ b/src/data.c
@@ -146,7 +146,7 @@ static inline void skb_encrypt(struct sk_buff *skb, struct noise_keypair *keypai
 
 	/* Only after checksumming can we safely add on the padding at the end and the header. */
 	header = (struct message_data *)skb_push(skb, sizeof(struct message_data));
-	header->header.type = MESSAGE_DATA;
+	header->header.type = cpu_to_le32(MESSAGE_DATA);
 	header->key_idx = keypair->remote_index;
 	header->counter = cpu_to_le64(cb->nonce);
 	pskb_put(skb, cb->trailer, cb->trailer_len);
diff --git a/src/messages.h b/src/messages.h
index e39bdab..f5362ac 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -63,13 +63,20 @@ enum message_type {
 };
 
 struct message_header {
-	u8 type;
-} __packed;
+	/* The actual layout of this that we want is:
+	 * u8 type
+	 * u8 reserved_zero[3]
+	 *
+	 * But it turns out that by encoding this as little endian,
+	 * we achieve the same thing, and it makes checking faster.
+	 */
+	__le32 type;
+};
 
 struct message_macs {
 	u8 mac1[COOKIE_LEN];
 	u8 mac2[COOKIE_LEN];
-} __packed;
+};
 
 struct message_handshake_initiation {
 	struct message_header header;
@@ -78,7 +85,7 @@ struct message_handshake_initiation {
 	u8 encrypted_static[noise_encrypted_len(NOISE_PUBLIC_KEY_LEN)];
 	u8 encrypted_timestamp[noise_encrypted_len(NOISE_TIMESTAMP_LEN)];
 	struct message_macs macs;
-} __packed;
+};
 
 struct message_handshake_response {
 	struct message_header header;
@@ -87,21 +94,21 @@ struct message_handshake_response {
 	u8 unencrypted_ephemeral[NOISE_PUBLIC_KEY_LEN];
 	u8 encrypted_nothing[noise_encrypted_len(0)];
 	struct message_macs macs;
-} __packed;
+};
 
 struct message_handshake_cookie {
 	struct message_header header;
 	__le32 receiver_index;
 	u8 salt[COOKIE_SALT_LEN];
 	u8 encrypted_cookie[noise_encrypted_len(COOKIE_LEN)];
-} __packed;
+};
 
 struct message_data {
 	struct message_header header;
 	__le32 key_idx;
 	__le64 counter;
 	u8 encrypted_data[];
-} __packed;
+};
 
 #define message_data_len(plain_len) (noise_encrypted_len(plain_len) + sizeof(struct message_data))
 
@@ -122,13 +129,13 @@ static inline enum message_type message_determine_type(void *src, size_t src_len
 	struct message_header *header = src;
 	if (unlikely(src_len < sizeof(struct message_header)))
 		return MESSAGE_INVALID;
-	if (header->type == MESSAGE_DATA && src_len >= MESSAGE_MINIMUM_LENGTH)
+	if (header->type == cpu_to_le32(MESSAGE_DATA) && src_len >= MESSAGE_MINIMUM_LENGTH)
 		return MESSAGE_DATA;
-	if (header->type == MESSAGE_HANDSHAKE_INITIATION && src_len == sizeof(struct message_handshake_initiation))
+	if (header->type == cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION) && src_len == sizeof(struct message_handshake_initiation))
 		return MESSAGE_HANDSHAKE_INITIATION;
-	if (header->type == MESSAGE_HANDSHAKE_RESPONSE && src_len == sizeof(struct message_handshake_response))
+	if (header->type == cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE) && src_len == sizeof(struct message_handshake_response))
 		return MESSAGE_HANDSHAKE_RESPONSE;
-	if (header->type == MESSAGE_HANDSHAKE_COOKIE && src_len == sizeof(struct message_handshake_cookie))
+	if (header->type == cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE) && src_len == sizeof(struct message_handshake_cookie))
 		return MESSAGE_HANDSHAKE_COOKIE;
 	return MESSAGE_INVALID;
 }
diff --git a/src/noise.c b/src/noise.c
index 7fd16b7..3fccd1e 100644
--- a/src/noise.c
+++ b/src/noise.c
@@ -339,7 +339,7 @@ bool noise_handshake_create_initiation(struct message_handshake_initiation *dst,
 	if (unlikely(!handshake->static_identity->has_identity))
 		goto out;
 
-	dst->header.type = MESSAGE_HANDSHAKE_INITIATION;
+	dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION);
 
 	handshake_init(handshake->key, handshake->chaining_key, handshake->hash, handshake->remote_static,
 		       handshake->static_identity->has_psk ? handshake->static_identity->preshared_key : NULL);
@@ -459,7 +459,7 @@ bool noise_handshake_create_response(struct message_handshake_response *dst, str
 	if (handshake->state != HANDSHAKE_CONSUMED_INITIATION)
 		goto out;
 
-	dst->header.type = MESSAGE_HANDSHAKE_RESPONSE;
+	dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE);
 	dst->receiver_index = handshake->remote_index;
 
 	/* e */