[PATCH 4/7] mac80211: Update BIP to support Beacon frames

[Jouni Malinen <jouni@xxxxxxxxxxxxxx>]

When BIP is used to protect Beacon frames, the Timestamp field is masked
to zero. Otherwise, the BIP processing is identical to the way it was
already used with group-addressed Robust Management frames.

Signed-off-by: Jouni Malinen <jouni@xxxxxxxxxxxxxx>
---
 net/mac80211/aes_cmac.c | 21 +++++++++++++++++++--
 net/mac80211/aes_gmac.c | 24 ++++++++++++++++++------
 2 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/net/mac80211/aes_cmac.c b/net/mac80211/aes_cmac.c
index 57748cab0e28..b31f1021ad9c 100644
--- a/net/mac80211/aes_cmac.c
+++ b/net/mac80211/aes_cmac.c
@@ -26,12 +26,20 @@ void ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
 {
 	SHASH_DESC_ON_STACK(desc, tfm);
 	u8 out[AES_BLOCK_SIZE];
+	const __le16 *fc;
 
 	desc->tfm = tfm;
 
 	crypto_shash_init(desc);
 	crypto_shash_update(desc, aad, AAD_LEN);
-	crypto_shash_update(desc, data, data_len - CMAC_TLEN);
+	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);
+	} else {
+		crypto_shash_update(desc, data, data_len - CMAC_TLEN);
+	}
 	crypto_shash_finup(desc, zero, CMAC_TLEN, out);
 
 	memcpy(mic, out, CMAC_TLEN);
@@ -41,12 +49,21 @@ void ieee80211_aes_cmac_256(struct crypto_shash *tfm, const u8 *aad,
 			    const u8 *data, size_t data_len, u8 *mic)
 {
 	SHASH_DESC_ON_STACK(desc, tfm);
+	const __le16 *fc;
 
 	desc->tfm = tfm;
 
 	crypto_shash_init(desc);
 	crypto_shash_update(desc, aad, AAD_LEN);
-	crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
+	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);
+	} else {
+		crypto_shash_update(desc, data, data_len - CMAC_TLEN_256);
+	}
 	crypto_shash_finup(desc, zero, CMAC_TLEN_256, mic);
 }
 
diff --git a/net/mac80211/aes_gmac.c b/net/mac80211/aes_gmac.c
index 363ad1c1dc0c..16ba09cb5def 100644
--- a/net/mac80211/aes_gmac.c
+++ b/net/mac80211/aes_gmac.c
@@ -17,10 +17,11 @@
 int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
 		       const u8 *data, size_t data_len, u8 *mic)
 {
-	struct scatterlist sg[4];
+	struct scatterlist sg[5];
 	u8 *zero, *__aad, iv[AES_BLOCK_SIZE];
 	struct aead_request *aead_req;
 	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	const __le16 *fc;
 
 	if (data_len < GMAC_MIC_LEN)
 		return -EINVAL;
@@ -33,11 +34,22 @@ int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
 	__aad = zero + GMAC_MIC_LEN;
 	memcpy(__aad, aad, GMAC_AAD_LEN);
 
-	sg_init_table(sg, 4);
-	sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
-	sg_set_buf(&sg[1], data, data_len - GMAC_MIC_LEN);
-	sg_set_buf(&sg[2], zero, GMAC_MIC_LEN);
-	sg_set_buf(&sg[3], mic, GMAC_MIC_LEN);
+	fc = (const __le16 *)aad;
+	if (ieee80211_is_beacon(*fc)) {
+		/* mask Timestamp field to zero */
+		sg_init_table(sg, 5);
+		sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
+		sg_set_buf(&sg[1], zero, 8);
+		sg_set_buf(&sg[2], data + 8, data_len - 8 - GMAC_MIC_LEN);
+		sg_set_buf(&sg[3], zero, GMAC_MIC_LEN);
+		sg_set_buf(&sg[4], mic, GMAC_MIC_LEN);
+	} else {
+		sg_init_table(sg, 4);
+		sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
+		sg_set_buf(&sg[1], data, data_len - GMAC_MIC_LEN);
+		sg_set_buf(&sg[2], zero, GMAC_MIC_LEN);
+		sg_set_buf(&sg[3], mic, GMAC_MIC_LEN);
+	}
 
 	memcpy(iv, nonce, GMAC_NONCE_LEN);
 	memset(iv + GMAC_NONCE_LEN, 0, sizeof(iv) - GMAC_NONCE_LEN);
-- 
2.20.1