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staging: rtl8192e: rtllib_crypt_ccmp.c: Use crypto API ccm(aes)
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Use ccm(aes) aead transform instead of invoking the AES block cipher
block by block.

Signed-off-by: Christina Quast <contact@christina-quast.de>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Link: https://lore.kernel.org/r/20190816065936.12214-3-contact@christina-quast.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Christina Quast authored and Greg Kroah-Hartman committed Aug 18, 2019
1 parent eb0e7bf commit 5ee5265
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Showing 2 changed files with 86 additions and 118 deletions.
1 change: 1 addition & 0 deletions drivers/staging/rtl8192e/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ config RTLLIB_CRYPTO_CCMP
tristate "Support for rtllib CCMP crypto"
depends on RTLLIB
select CRYPTO_AES
select CRYPTO_CCM
default y
help
CCMP crypto driver for rtllib.
Expand Down
203 changes: 85 additions & 118 deletions drivers/staging/rtl8192e/rtllib_crypt_ccmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include "rtllib.h"

#include <linux/crypto.h>
#include <crypto/aead.h>

#include <linux/scatterlist.h>

Expand All @@ -39,20 +40,13 @@ struct rtllib_ccmp_data {

int key_idx;

struct crypto_tfm *tfm;
struct crypto_aead *tfm;

/* scratch buffers for virt_to_page() (crypto API) */
u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
u8 tx_aad[2 * AES_BLOCK_LEN];
u8 rx_aad[2 * AES_BLOCK_LEN];
};

static void rtllib_ccmp_aes_encrypt(struct crypto_tfm *tfm,
const u8 pt[16], u8 ct[16])
{
crypto_cipher_encrypt_one((void *)tfm, ct, pt);
}

static void *rtllib_ccmp_init(int key_idx)
{
struct rtllib_ccmp_data *priv;
Expand All @@ -62,7 +56,7 @@ static void *rtllib_ccmp_init(int key_idx)
goto fail;
priv->key_idx = key_idx;

priv->tfm = (void *)crypto_alloc_cipher("aes", 0, 0);
priv->tfm = crypto_alloc_aead("ccm(aes)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(priv->tfm)) {
pr_debug("Could not allocate crypto API aes\n");
priv->tfm = NULL;
Expand All @@ -73,7 +67,7 @@ static void *rtllib_ccmp_init(int key_idx)
fail:
if (priv) {
if (priv->tfm)
crypto_free_cipher((void *)priv->tfm);
crypto_free_aead(priv->tfm);
kfree(priv);
}

Expand All @@ -86,31 +80,18 @@ static void rtllib_ccmp_deinit(void *priv)
struct rtllib_ccmp_data *_priv = priv;

if (_priv && _priv->tfm)
crypto_free_cipher((void *)_priv->tfm);
crypto_free_aead(_priv->tfm);
kfree(priv);
}


static inline void xor_block(u8 *b, u8 *a, size_t len)
{
int i;

for (i = 0; i < len; i++)
b[i] ^= a[i];
}



static void ccmp_init_blocks(struct crypto_tfm *tfm,
struct rtllib_hdr_4addr *hdr,
u8 *pn, size_t dlen, u8 *b0, u8 *auth,
u8 *s0)
static int ccmp_init_iv_and_aad(struct rtllib_hdr_4addr *hdr,
u8 *pn, u8 *iv, u8 *aad)
{
u8 *pos, qc = 0;
size_t aad_len;
u16 fc;
int a4_included, qc_included;
u8 aad[2 * AES_BLOCK_LEN];

fc = le16_to_cpu(hdr->frame_ctl);
a4_included = ((fc & (RTLLIB_FCTL_TODS | RTLLIB_FCTL_FROMDS)) ==
Expand All @@ -128,18 +109,19 @@ static void ccmp_init_blocks(struct crypto_tfm *tfm,
qc = *pos & 0x0f;
aad_len += 2;
}
/* CCM Initial Block:
* Flag (Include authentication header, M=3 (8-octet MIC),
* L=1 (2-octet Dlen))
* Nonce: 0x00 | A2 | PN
* Dlen
/* 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 the same vector. 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.
*/
b0[0] = 0x59;
b0[1] = qc;
memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
memcpy(b0 + 8, pn, CCMP_PN_LEN);
b0[14] = (dlen >> 8) & 0xff;
b0[15] = dlen & 0xff;
iv[0] = 0x1;

/* Nonce: QC | A2 | PN */
iv[1] = qc;
memcpy(iv + 2, hdr->addr2, ETH_ALEN);
memcpy(iv + 8, pn, CCMP_PN_LEN);

/* AAD:
* FC with bits 4..6 and 11..13 masked to zero; 14 is always one
Expand All @@ -149,31 +131,21 @@ static void ccmp_init_blocks(struct crypto_tfm *tfm,
* QC (if present)
*/
pos = (u8 *) hdr;
aad[0] = 0; /* aad_len >> 8 */
aad[1] = aad_len & 0xff;
aad[2] = pos[0] & 0x8f;
aad[3] = pos[1] & 0xc7;
memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
aad[0] = pos[0] & 0x8f;
aad[1] = pos[1] & 0xc7;
memcpy(aad + 2, hdr->addr1, 3 * ETH_ALEN);
pos = (u8 *) &hdr->seq_ctl;
aad[22] = pos[0] & 0x0f;
aad[23] = 0; /* all bits masked */
memset(aad + 24, 0, 8);
aad[20] = pos[0] & 0x0f;
aad[21] = 0; /* all bits masked */
memset(aad + 22, 0, 8);
if (a4_included)
memcpy(aad + 24, hdr->addr4, ETH_ALEN);
memcpy(aad + 22, hdr->addr4, ETH_ALEN);
if (qc_included) {
aad[a4_included ? 30 : 24] = qc;
aad[a4_included ? 28 : 22] = qc;
/* rest of QC masked */
}

/* Start with the first block and AAD */
rtllib_ccmp_aes_encrypt(tfm, b0, auth);
xor_block(auth, aad, AES_BLOCK_LEN);
rtllib_ccmp_aes_encrypt(tfm, auth, auth);
xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
rtllib_ccmp_aes_encrypt(tfm, auth, auth);
b0[0] &= 0x07;
b0[14] = b0[15] = 0;
rtllib_ccmp_aes_encrypt(tfm, b0, s0);
return aad_len;
}


Expand Down Expand Up @@ -213,40 +185,37 @@ static int rtllib_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
*pos++ = key->tx_pn[1];
*pos++ = key->tx_pn[0];


hdr = (struct rtllib_hdr_4addr *) skb->data;
if (!tcb_desc->bHwSec) {
int blocks, last, len;
u8 *mic;
u8 *b0 = key->tx_b0;
u8 *b = key->tx_b;
u8 *e = key->tx_e;
u8 *s0 = key->tx_s0;

mic = skb_put(skb, CCMP_MIC_LEN);

ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len,
b0, b, s0);

blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
last = data_len % AES_BLOCK_LEN;

for (i = 1; i <= blocks; i++) {
len = (i == blocks && last) ? last : AES_BLOCK_LEN;
/* Authentication */
xor_block(b, pos, len);
rtllib_ccmp_aes_encrypt(key->tfm, b, b);
/* Encryption, with counter */
b0[14] = (i >> 8) & 0xff;
b0[15] = i & 0xff;
rtllib_ccmp_aes_encrypt(key->tfm, b0, e);
xor_block(pos, e, len);
pos += len;
}
struct aead_request *req;
struct scatterlist sg[2];
u8 *aad = key->tx_aad;
u8 iv[AES_BLOCK_LEN];
int aad_len, ret;
int data_len = skb->len - hdr_len - CCMP_HDR_LEN;

for (i = 0; i < CCMP_MIC_LEN; i++)
mic[i] = b[i] ^ s0[i];
req = aead_request_alloc(key->tfm, GFP_ATOMIC);
if (!req)
return -ENOMEM;

aad_len = ccmp_init_iv_and_aad(hdr, key->tx_pn, iv, aad);

skb_put(skb, CCMP_MIC_LEN);
sg_init_table(sg, 2);
sg_set_buf(&sg[0], aad, aad_len);
sg_set_buf(&sg[1], skb->data + hdr_len + CCMP_HDR_LEN,
data_len + CCMP_MIC_LEN);

aead_request_set_callback(req, 0, NULL, NULL);
aead_request_set_ad(req, aad_len);
aead_request_set_crypt(req, sg, sg, data_len, iv);

ret = crypto_aead_encrypt(req);
aead_request_free(req);

return ret;
}

return 0;
}

Expand Down Expand Up @@ -302,35 +271,31 @@ static int rtllib_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
return -4;
}
if (!tcb_desc->bHwSec) {
size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN -
CCMP_MIC_LEN;
u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
u8 *b0 = key->rx_b0;
u8 *b = key->rx_b;
u8 *a = key->rx_a;
int i, blocks, last, len;


ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
xor_block(mic, b, CCMP_MIC_LEN);

blocks = DIV_ROUND_UP(data_len, AES_BLOCK_LEN);
last = data_len % AES_BLOCK_LEN;

for (i = 1; i <= blocks; i++) {
len = (i == blocks && last) ? last : AES_BLOCK_LEN;
/* Decrypt, with counter */
b0[14] = (i >> 8) & 0xff;
b0[15] = i & 0xff;
rtllib_ccmp_aes_encrypt(key->tfm, b0, b);
xor_block(pos, b, len);
/* Authentication */
xor_block(a, pos, len);
rtllib_ccmp_aes_encrypt(key->tfm, a, a);
pos += len;
}
size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN;
struct aead_request *req;
struct scatterlist sg[2];
u8 *aad = key->rx_aad;
u8 iv[AES_BLOCK_LEN];
int aad_len, ret;

req = aead_request_alloc(key->tfm, GFP_ATOMIC);
if(!req)
return -ENOMEM;

aad_len = ccmp_init_iv_and_aad(hdr, pn, iv, aad);

sg_init_table(sg, 2);
sg_set_buf(&sg[0], aad, aad_len);
sg_set_buf(&sg[1], pos, data_len);

aead_request_set_callback(req, 0, NULL, NULL);
aead_request_set_ad(req, aad_len);
aead_request_set_crypt(req, sg, sg, data_len, iv);

ret = crypto_aead_decrypt(req);
aead_request_free(req);

if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
if (ret) {
if (net_ratelimit()) {
pr_debug("CCMP: decrypt failed: STA= %pM\n",
hdr->addr2);
Expand All @@ -354,7 +319,7 @@ static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
{
struct rtllib_ccmp_data *data = priv;
int keyidx;
struct crypto_tfm *tfm = data->tfm;
struct crypto_aead *tfm = data->tfm;

keyidx = data->key_idx;
memset(data, 0, sizeof(*data));
Expand All @@ -371,7 +336,9 @@ static int rtllib_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
data->rx_pn[4] = seq[1];
data->rx_pn[5] = seq[0];
}
crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
if (crypto_aead_setauthsize(data->tfm, CCMP_MIC_LEN) ||
crypto_aead_setkey(data->tfm, data->key, CCMP_TK_LEN))
return -1;
} else if (len == 0) {
data->key_set = 0;
} else {
Expand Down

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