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wifi: mac80211: Use AES-CMAC library in ieee80211_aes_cmac() 

Now that AES-CMAC has a library API, convert the mac80211 AES-CMAC
packet authentication code to use it instead of a "cmac(aes)"
crypto_shash.  This has multiple benefits, such as:

- It's faster.  The AES-CMAC code is now called directly, without
  unnecessary overhead such as indirect calls.

- MAC calculation can no longer fail.

- The AES-CMAC key struct is now a fixed size, allowing it to be
  embedded directly into 'struct ieee80211_key' rather than using a
  separate allocation.  Note that although this increases the size of
  the 'u.cmac' field of 'struct ieee80211_key', it doesn't cause it to
  exceed the size of the largest variant of the union 'u'.  Therefore,
  the size of 'struct ieee80211_key' itself is unchanged.

Acked-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260218213501.136844-15-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
master
Eric Biggers 2026-02-18 13:35:00 -08:00
parent 2505f9157e
commit c9de7246d5
6 changed files with 26 additions and 79 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
net/mac80211/Kconfig
View File

@ -3,6 +3,7 @@ config MAC80211
tristate "Generic IEEE 802.11 Networking Stack (mac80211)"
depends on CFG80211
select CRYPTO
select CRYPTO_LIB_AES_CBC_MACS
select CRYPTO_LIB_ARC4
select CRYPTO_AES
select CRYPTO_CCM

65
net/mac80211/aes_cmac.c
View File

@ -7,10 +7,9 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/crypto.h>
#include <linux/export.h>
#include <linux/err.h>
#include <crypto/aes.h>
#include <crypto/aes-cbc-macs.h>
#include <net/mac80211.h>
#include "key.h"
@ -20,65 +19,25 @@
static const u8 zero[IEEE80211_CMAC_256_MIC_LEN];
int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
const u8 *data, size_t data_len, u8 *mic,
unsigned int mic_len)
void ieee80211_aes_cmac(const struct aes_cmac_key *key, const u8 *aad,
const u8 *data, size_t data_len, u8 *mic,
unsigned int mic_len)
{
int err;
SHASH_DESC_ON_STACK(desc, tfm);
struct aes_cmac_ctx ctx;
u8 out[AES_BLOCK_SIZE];
const __le16 *fc;
desc->tfm = tfm;
err = crypto_shash_init(desc);
if (err)
return err;
err = crypto_shash_update(desc, aad, AAD_LEN);
if (err)
return err;
aes_cmac_init(&ctx, key);
aes_cmac_update(&ctx, aad, AAD_LEN);
fc = (const __le16 *)aad;
if (ieee80211_is_beacon(*fc)) {
/* mask Timestamp field to zero */
err = crypto_shash_update(desc, zero, 8);
if (err)
return err;
err = crypto_shash_update(desc, data + 8,
data_len - 8 - mic_len);
if (err)
return err;
aes_cmac_update(&ctx, zero, 8);
aes_cmac_update(&ctx, data + 8, data_len - 8 - mic_len);
} else {
err = crypto_shash_update(desc, data, data_len - mic_len);
if (err)
return err;
aes_cmac_update(&ctx, data, data_len - mic_len);
}
err = crypto_shash_finup(desc, zero, mic_len, out);
if (err)
return err;
aes_cmac_update(&ctx, zero, mic_len);
aes_cmac_final(&ctx, out);
memcpy(mic, out, mic_len);
return 0;
}
struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
size_t key_len)
{
struct crypto_shash *tfm;
tfm = crypto_alloc_shash("cmac(aes)", 0, 0);
if (!IS_ERR(tfm)) {
int err = crypto_shash_setkey(tfm, key, key_len);
if (err) {
crypto_free_shash(tfm);
return ERR_PTR(err);
}
}
return tfm;
}
void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm)
{
crypto_free_shash(tfm);
}

12
net/mac80211/aes_cmac.h
View File

@ -6,14 +6,10 @@
#ifndef AES_CMAC_H
#define AES_CMAC_H
#include <linux/crypto.h>
#include <crypto/hash.h>
#include <crypto/aes-cbc-macs.h>
struct crypto_shash *ieee80211_aes_cmac_key_setup(const u8 key[],
size_t key_len);
int ieee80211_aes_cmac(struct crypto_shash *tfm, const u8 *aad,
const u8 *data, size_t data_len, u8 *mic,
unsigned int mic_len);
void ieee80211_aes_cmac_key_free(struct crypto_shash *tfm);
void ieee80211_aes_cmac(const struct aes_cmac_key *key, const u8 *aad,
const u8 *data, size_t data_len, u8 *mic,
unsigned int mic_len);
#endif /* AES_CMAC_H */

11
net/mac80211/key.c
View File

@ -690,10 +690,9 @@ ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
* Initialize AES key state here as an optimization so that
* it does not need to be initialized for every packet.
*/
key->u.aes_cmac.tfm =
ieee80211_aes_cmac_key_setup(key_data, key_len);
if (IS_ERR(key->u.aes_cmac.tfm)) {
err = PTR_ERR(key->u.aes_cmac.tfm);
err = aes_cmac_preparekey(&key->u.aes_cmac.key, key_data,
key_len);
if (err) {
kfree(key);
return ERR_PTR(err);
}
@ -750,10 +749,6 @@ static void ieee80211_key_free_common(struct ieee80211_key *key)
case WLAN_CIPHER_SUITE_CCMP_256:
ieee80211_aes_key_free(key->u.ccmp.tfm);
break;
case WLAN_CIPHER_SUITE_AES_CMAC:
case WLAN_CIPHER_SUITE_BIP_CMAC_256:
ieee80211_aes_cmac_key_free(key->u.aes_cmac.tfm);
break;
case WLAN_CIPHER_SUITE_BIP_GMAC_128:
case WLAN_CIPHER_SUITE_BIP_GMAC_256:
ieee80211_aes_gmac_key_free(key->u.aes_gmac.tfm);

3
net/mac80211/key.h
View File

@ -12,6 +12,7 @@
#include <linux/list.h>
#include <linux/crypto.h>
#include <linux/rcupdate.h>
#include <crypto/aes-cbc-macs.h>
#include <crypto/arc4.h>
#include <net/mac80211.h>
@ -93,7 +94,7 @@ struct ieee80211_key {
} ccmp;
struct {
u8 rx_pn[IEEE80211_CMAC_PN_LEN];
struct crypto_shash *tfm;
struct aes_cmac_key key;
u32 replays; /* dot11RSNAStatsCMACReplays */
u32 icverrors; /* dot11RSNAStatsCMACICVErrors */
} aes_cmac;

13
net/mac80211/wpa.c
View File

@ -872,11 +872,8 @@ ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx,
bip_aad(skb, aad);
if (ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
skb->data + 24, skb->len - 24,
mmie->mic, mic_len))
return TX_DROP;
ieee80211_aes_cmac(&key->u.aes_cmac.key, aad, skb->data + 24,
skb->len - 24, mmie->mic, mic_len);
return TX_CONTINUE;
}
@ -918,10 +915,8 @@ ieee80211_crypto_aes_cmac_decrypt(struct ieee80211_rx_data *rx,
if (!(status->flag & RX_FLAG_DECRYPTED)) {
/* hardware didn't decrypt/verify MIC */
bip_aad(skb, aad);
if (ieee80211_aes_cmac(key->u.aes_cmac.tfm, aad,
skb->data + 24, skb->len - 24,
mic, mic_len))
return RX_DROP_U_DECRYPT_FAIL;
ieee80211_aes_cmac(&key->u.aes_cmac.key, aad, skb->data + 24,
skb->len - 24, mic, mic_len);
if (crypto_memneq(mic, mmie->mic, mic_len)) {
key->u.aes_cmac.icverrors++;
return RX_DROP_U_MIC_FAIL;