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Date: Thu, 10 Oct 2013 09:55:20 +0200
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Cc: patches@...aro.org, johannes@...solutions.net,
Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: [PATCH v3] mac80211: port CCMP to cryptoapi's CCM driver
Use the generic CCM aead chaining mode driver rather than a local
implementation that sits right on top of the core AES cipher.
This allows the use of accelerated implementations of either
CCM as a whole or the CTR mode which it encapsulates.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
Changes since v2:
- removed the redundant length setting in vector b_0 (and updated the comment
accordingly);
Changes since v1:
- use a better way to allocate the variable size aead_request struct on the
stack;
- pass only a single data pointer argument as we always encrypt/decrypt in
place;
- add a comment about how vector b_0 is generated.
net/mac80211/Kconfig | 1 +
net/mac80211/aes_ccm.c | 169 ++++++++++++++++---------------------------------
net/mac80211/aes_ccm.h | 14 ++--
net/mac80211/key.h | 2 +-
net/mac80211/wpa.c | 44 ++++++-------
5 files changed, 84 insertions(+), 146 deletions(-)
diff --git a/net/mac80211/Kconfig b/net/mac80211/Kconfig
index 62535fe..dc31ec3 100644
--- a/net/mac80211/Kconfig
+++ b/net/mac80211/Kconfig
@@ -4,6 +4,7 @@ config MAC80211
select CRYPTO
select CRYPTO_ARC4
select CRYPTO_AES
+ select CRYPTO_CCM
select CRC32
select AVERAGE
---help---
diff --git a/net/mac80211/aes_ccm.c b/net/mac80211/aes_ccm.c
index be7614b9..7c7df47 100644
--- a/net/mac80211/aes_ccm.c
+++ b/net/mac80211/aes_ccm.c
@@ -2,6 +2,8 @@
* Copyright 2003-2004, Instant802 Networks, Inc.
* Copyright 2005-2006, Devicescape Software, Inc.
*
+ * Rewrite: Copyright (C) 2013 Linaro Ltd <ard.biesheuvel@...aro.org>
+ *
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
@@ -17,134 +19,75 @@
#include "key.h"
#include "aes_ccm.h"
-static void aes_ccm_prepare(struct crypto_cipher *tfm, u8 *scratch, u8 *a)
+void ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
+ u8 *data, size_t data_len, u8 *mic)
{
- int i;
- u8 *b_0, *aad, *b, *s_0;
-
- b_0 = scratch + 3 * AES_BLOCK_SIZE;
- aad = scratch + 4 * AES_BLOCK_SIZE;
- b = scratch;
- s_0 = scratch + AES_BLOCK_SIZE;
-
- crypto_cipher_encrypt_one(tfm, b, b_0);
+ struct scatterlist assoc, pt, ct[2];
+ struct {
+ struct aead_request req;
+ u8 priv[crypto_aead_reqsize(tfm)];
+ } aead_req;
- /* Extra Authenticate-only data (always two AES blocks) */
- for (i = 0; i < AES_BLOCK_SIZE; i++)
- aad[i] ^= b[i];
- crypto_cipher_encrypt_one(tfm, b, aad);
+ memset(&aead_req, 0, sizeof(aead_req));
- aad += AES_BLOCK_SIZE;
+ sg_init_one(&pt, data, data_len);
+ sg_init_one(&assoc, &aad[2], be16_to_cpup((__be16 *)aad));
+ sg_init_table(ct, 2);
+ sg_set_buf(&ct[0], data, data_len);
+ sg_set_buf(&ct[1], mic, IEEE80211_CCMP_MIC_LEN);
- for (i = 0; i < AES_BLOCK_SIZE; i++)
- aad[i] ^= b[i];
- crypto_cipher_encrypt_one(tfm, a, aad);
+ aead_request_set_tfm(&aead_req.req, tfm);
+ aead_request_set_assoc(&aead_req.req, &assoc, assoc.length);
+ aead_request_set_crypt(&aead_req.req, &pt, ct, data_len, b_0);
- /* Mask out bits from auth-only-b_0 */
- b_0[0] &= 0x07;
-
- /* S_0 is used to encrypt T (= MIC) */
- b_0[14] = 0;
- b_0[15] = 0;
- crypto_cipher_encrypt_one(tfm, s_0, b_0);
+ crypto_aead_encrypt(&aead_req.req);
}
-
-void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch,
- u8 *data, size_t data_len,
- u8 *cdata, u8 *mic)
+int ieee80211_aes_ccm_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
+ u8 *data, size_t data_len, u8 *mic)
{
- int i, j, last_len, num_blocks;
- u8 *pos, *cpos, *b, *s_0, *e, *b_0;
-
- b = scratch;
- s_0 = scratch + AES_BLOCK_SIZE;
- e = scratch + 2 * AES_BLOCK_SIZE;
- b_0 = scratch + 3 * AES_BLOCK_SIZE;
-
- num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_SIZE);
- last_len = data_len % AES_BLOCK_SIZE;
- aes_ccm_prepare(tfm, scratch, b);
-
- /* Process payload blocks */
- pos = data;
- cpos = cdata;
- for (j = 1; j <= num_blocks; j++) {
- int blen = (j == num_blocks && last_len) ?
- last_len : AES_BLOCK_SIZE;
-
- /* Authentication followed by encryption */
- for (i = 0; i < blen; i++)
- b[i] ^= pos[i];
- crypto_cipher_encrypt_one(tfm, b, b);
-
- b_0[14] = (j >> 8) & 0xff;
- b_0[15] = j & 0xff;
- crypto_cipher_encrypt_one(tfm, e, b_0);
- for (i = 0; i < blen; i++)
- *cpos++ = *pos++ ^ e[i];
- }
-
- for (i = 0; i < IEEE80211_CCMP_MIC_LEN; i++)
- mic[i] = b[i] ^ s_0[i];
+ struct scatterlist assoc, pt, ct[2];
+ struct {
+ struct aead_request req;
+ u8 priv[crypto_aead_reqsize(tfm)];
+ } aead_req;
+
+ memset(&aead_req, 0, sizeof(aead_req));
+
+ sg_init_one(&pt, data, data_len);
+ sg_init_one(&assoc, &aad[2], be16_to_cpup((__be16 *)aad));
+ sg_init_table(ct, 2);
+ sg_set_buf(&ct[0], data, data_len);
+ sg_set_buf(&ct[1], mic, IEEE80211_CCMP_MIC_LEN);
+
+ aead_request_set_tfm(&aead_req.req, tfm);
+ aead_request_set_assoc(&aead_req.req, &assoc, assoc.length);
+ aead_request_set_crypt(&aead_req.req, ct, &pt,
+ data_len + IEEE80211_CCMP_MIC_LEN, b_0);
+
+ return crypto_aead_decrypt(&aead_req.req);
}
-
-int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch,
- u8 *cdata, size_t data_len, u8 *mic, u8 *data)
+struct crypto_aead *ieee80211_aes_key_setup_encrypt(const u8 key[])
{
- int i, j, last_len, num_blocks;
- u8 *pos, *cpos, *b, *s_0, *a, *b_0;
-
- b = scratch;
- s_0 = scratch + AES_BLOCK_SIZE;
- a = scratch + 2 * AES_BLOCK_SIZE;
- b_0 = scratch + 3 * AES_BLOCK_SIZE;
-
- num_blocks = DIV_ROUND_UP(data_len, AES_BLOCK_SIZE);
- last_len = data_len % AES_BLOCK_SIZE;
- aes_ccm_prepare(tfm, scratch, a);
-
- /* Process payload blocks */
- cpos = cdata;
- pos = data;
- for (j = 1; j <= num_blocks; j++) {
- int blen = (j == num_blocks && last_len) ?
- last_len : AES_BLOCK_SIZE;
-
- /* Decryption followed by authentication */
- b_0[14] = (j >> 8) & 0xff;
- b_0[15] = j & 0xff;
- crypto_cipher_encrypt_one(tfm, b, b_0);
- for (i = 0; i < blen; i++) {
- *pos = *cpos++ ^ b[i];
- a[i] ^= *pos++;
- }
- crypto_cipher_encrypt_one(tfm, a, a);
- }
-
- for (i = 0; i < IEEE80211_CCMP_MIC_LEN; i++) {
- if ((mic[i] ^ s_0[i]) != a[i])
- return -1;
- }
-
- return 0;
-}
+ struct crypto_aead *tfm;
+ int err;
+ tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(tfm))
+ return tfm;
-struct crypto_cipher *ieee80211_aes_key_setup_encrypt(const u8 key[])
-{
- struct crypto_cipher *tfm;
+ err = crypto_aead_setkey(tfm, key, WLAN_KEY_LEN_CCMP);
+ if (!err)
+ err = crypto_aead_setauthsize(tfm, IEEE80211_CCMP_MIC_LEN);
+ if (!err)
+ return tfm;
- tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
- if (!IS_ERR(tfm))
- crypto_cipher_setkey(tfm, key, WLAN_KEY_LEN_CCMP);
-
- return tfm;
+ crypto_free_aead(tfm);
+ return ERR_PTR(err);
}
-
-void ieee80211_aes_key_free(struct crypto_cipher *tfm)
+void ieee80211_aes_key_free(struct crypto_aead *tfm)
{
- crypto_free_cipher(tfm);
+ crypto_free_aead(tfm);
}
diff --git a/net/mac80211/aes_ccm.h b/net/mac80211/aes_ccm.h
index 5b7d744..2c7ab19 100644
--- a/net/mac80211/aes_ccm.h
+++ b/net/mac80211/aes_ccm.h
@@ -12,13 +12,11 @@
#include <linux/crypto.h>
-struct crypto_cipher *ieee80211_aes_key_setup_encrypt(const u8 key[]);
-void ieee80211_aes_ccm_encrypt(struct crypto_cipher *tfm, u8 *scratch,
- u8 *data, size_t data_len,
- u8 *cdata, u8 *mic);
-int ieee80211_aes_ccm_decrypt(struct crypto_cipher *tfm, u8 *scratch,
- u8 *cdata, size_t data_len,
- u8 *mic, u8 *data);
-void ieee80211_aes_key_free(struct crypto_cipher *tfm);
+struct crypto_aead *ieee80211_aes_key_setup_encrypt(const u8 key[]);
+void ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
+ u8 *data, size_t data_len, u8 *mic);
+int ieee80211_aes_ccm_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
+ u8 *data, size_t data_len, u8 *mic);
+void ieee80211_aes_key_free(struct crypto_aead *tfm);
#endif /* AES_CCM_H */
diff --git a/net/mac80211/key.h b/net/mac80211/key.h
index 036d57e..aaae0ed 100644
--- a/net/mac80211/key.h
+++ b/net/mac80211/key.h
@@ -83,7 +83,7 @@ struct ieee80211_key {
* Management frames.
*/
u8 rx_pn[IEEE80211_NUM_TIDS + 1][IEEE80211_CCMP_PN_LEN];
- struct crypto_cipher *tfm;
+ struct crypto_aead *tfm;
u32 replays; /* dot11RSNAStatsCCMPReplays */
} ccmp;
struct {
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index c9edfcb..d657282 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -301,22 +301,16 @@ ieee80211_crypto_tkip_decrypt(struct ieee80211_rx_data *rx)
}
-static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
+static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *b_0, u8 *aad,
int encrypted)
{
__le16 mask_fc;
int a4_included, mgmt;
u8 qos_tid;
- u8 *b_0, *aad;
- u16 data_len, len_a;
+ u16 len_a;
unsigned int hdrlen;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
- memset(scratch, 0, 6 * AES_BLOCK_SIZE);
-
- b_0 = scratch + 3 * AES_BLOCK_SIZE;
- aad = scratch + 4 * AES_BLOCK_SIZE;
-
/*
* Mask FC: zero subtype b4 b5 b6 (if not mgmt)
* Retry, PwrMgt, MoreData; set Protected
@@ -338,20 +332,21 @@ static void ccmp_special_blocks(struct sk_buff *skb, u8 *pn, u8 *scratch,
else
qos_tid = 0;
- data_len = skb->len - hdrlen - IEEE80211_CCMP_HDR_LEN;
- if (encrypted)
- data_len -= IEEE80211_CCMP_MIC_LEN;
+ /* In CCM, the initial vectors (IV) used for CTR mode encryption and CBC
+ * mode authentication are not allowed to collide, yet both are derived
+ * from this vector b_0. We only set L := 1 here to indicate that the
+ * data size can be represented in (L+1) bytes. The CCM layer will take
+ * care of storing the data length in the top (L+1) bytes and setting
+ * and clearing the other bits as is required to derive the two IVs.
+ */
+ b_0[0] = 0x1;
- /* First block, b_0 */
- b_0[0] = 0x59; /* flags: Adata: 1, M: 011, L: 001 */
/* Nonce: Nonce Flags | A2 | PN
* Nonce Flags: Priority (b0..b3) | Management (b4) | Reserved (b5..b7)
*/
b_0[1] = qos_tid | (mgmt << 4);
memcpy(&b_0[2], hdr->addr2, ETH_ALEN);
memcpy(&b_0[8], pn, IEEE80211_CCMP_PN_LEN);
- /* l(m) */
- put_unaligned_be16(data_len, &b_0[14]);
/* AAD (extra authenticate-only data) / masked 802.11 header
* FC | A1 | A2 | A3 | SC | [A4] | [QC] */
@@ -407,7 +402,8 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
u8 *pos;
u8 pn[6];
u64 pn64;
- u8 scratch[6 * AES_BLOCK_SIZE];
+ u8 aad[2 * AES_BLOCK_SIZE];
+ u8 b_0[AES_BLOCK_SIZE];
if (info->control.hw_key &&
!(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
@@ -460,9 +456,9 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
return 0;
pos += IEEE80211_CCMP_HDR_LEN;
- ccmp_special_blocks(skb, pn, scratch, 0);
- ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, scratch, pos, len,
- pos, skb_put(skb, IEEE80211_CCMP_MIC_LEN));
+ ccmp_special_blocks(skb, pn, b_0, aad, 0);
+ ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
+ skb_put(skb, IEEE80211_CCMP_MIC_LEN));
return 0;
}
@@ -525,16 +521,16 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx)
}
if (!(status->flag & RX_FLAG_DECRYPTED)) {
- u8 scratch[6 * AES_BLOCK_SIZE];
+ u8 aad[2 * AES_BLOCK_SIZE];
+ u8 b_0[AES_BLOCK_SIZE];
/* hardware didn't decrypt/verify MIC */
- ccmp_special_blocks(skb, pn, scratch, 1);
+ ccmp_special_blocks(skb, pn, b_0, aad, 1);
if (ieee80211_aes_ccm_decrypt(
- key->u.ccmp.tfm, scratch,
+ key->u.ccmp.tfm, b_0, aad,
skb->data + hdrlen + IEEE80211_CCMP_HDR_LEN,
data_len,
- skb->data + skb->len - IEEE80211_CCMP_MIC_LEN,
- skb->data + hdrlen + IEEE80211_CCMP_HDR_LEN))
+ skb->data + skb->len - IEEE80211_CCMP_MIC_LEN))
return RX_DROP_UNUSABLE;
}
--
1.8.1.2
--
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