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- /*
- * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
- */
-
- FILE_LICENCE ( GPL2_OR_LATER );
-
- #include <string.h>
- #include <ipxe/net80211.h>
- #include <ipxe/crypto.h>
- #include <ipxe/hmac.h>
- #include <ipxe/sha1.h>
- #include <ipxe/aes.h>
- #include <ipxe/wpa.h>
- #include <byteswap.h>
- #include <errno.h>
-
- /** @file
- *
- * Backend for WPA using the CCMP encryption method
- */
-
- /** Context for CCMP encryption and decryption */
- struct ccmp_ctx
- {
- /** AES context - only ever used for encryption */
- u8 aes_ctx[AES_CTX_SIZE];
-
- /** Most recently sent packet number */
- u64 tx_seq;
-
- /** Most recently received packet number */
- u64 rx_seq;
- };
-
- /** Header structure at the beginning of CCMP frame data */
- struct ccmp_head
- {
- u8 pn_lo[2]; /**< Bytes 0 and 1 of packet number */
- u8 _rsvd; /**< Reserved byte */
- u8 kid; /**< Key ID and ExtIV byte */
- u8 pn_hi[4]; /**< Bytes 2-5 (2 first) of packet number */
- } __attribute__ (( packed ));
-
-
- /** CCMP header overhead */
- #define CCMP_HEAD_LEN 8
-
- /** CCMP MIC trailer overhead */
- #define CCMP_MIC_LEN 8
-
- /** CCMP nonce length */
- #define CCMP_NONCE_LEN 13
-
- /** CCMP nonce structure */
- struct ccmp_nonce
- {
- u8 prio; /**< Packet priority, 0 for non-QoS */
- u8 a2[ETH_ALEN]; /**< Address 2 from packet header (sender) */
- u8 pn[6]; /**< Packet number */
- } __attribute__ (( packed ));
-
- /** CCMP additional authentication data length (for non-QoS, non-WDS frames) */
- #define CCMP_AAD_LEN 22
-
- /** CCMP additional authentication data structure */
- struct ccmp_aad
- {
- u16 fc; /**< Frame Control field */
- u8 a1[6]; /**< Address 1 */
- u8 a2[6]; /**< Address 2 */
- u8 a3[6]; /**< Address 3 */
- u16 seq; /**< Sequence Control field */
- /* Address 4 and QoS Control are included if present */
- } __attribute__ (( packed ));
-
- /** Mask for Frame Control field in AAD */
- #define CCMP_AAD_FC_MASK 0xC38F
-
- /** Mask for Sequence Control field in AAD */
- #define CCMP_AAD_SEQ_MASK 0x000F
-
-
- /**
- * Convert 6-byte LSB packet number to 64-bit integer
- *
- * @v pn Pointer to 6-byte packet number
- * @ret v 64-bit integer value of @a pn
- */
- static u64 pn_to_u64 ( const u8 *pn )
- {
- int i;
- u64 ret = 0;
-
- for ( i = 5; i >= 0; i-- ) {
- ret <<= 8;
- ret |= pn[i];
- }
-
- return ret;
- }
-
- /**
- * Convert 64-bit integer to 6-byte packet number
- *
- * @v v 64-bit integer
- * @v msb If TRUE, reverse the output PN to be in MSB order
- * @ret pn 6-byte packet number
- *
- * The PN is stored in LSB order in the packet header and in MSB order
- * in the nonce. WHYYYYY?
- */
- static void u64_to_pn ( u64 v, u8 *pn, int msb )
- {
- int i;
- u8 *pnp = pn + ( msb ? 5 : 0 );
- int delta = ( msb ? -1 : +1 );
-
- for ( i = 0; i < 6; i++ ) {
- *pnp = v & 0xFF;
- pnp += delta;
- v >>= 8;
- }
- }
-
- /** Value for @a msb argument of u64_to_pn() for MSB output */
- #define PN_MSB 1
-
- /** Value for @a msb argument of u64_to_pn() for LSB output */
- #define PN_LSB 0
-
-
-
- /**
- * Initialise CCMP state and install key
- *
- * @v crypto CCMP cryptosystem structure
- * @v key Pointer to 16-byte temporal key to install
- * @v keylen Length of key (16 bytes)
- * @v rsc Initial receive sequence counter
- */
- static int ccmp_init ( struct net80211_crypto *crypto, const void *key,
- int keylen, const void *rsc )
- {
- struct ccmp_ctx *ctx = crypto->priv;
-
- if ( keylen != 16 )
- return -EINVAL;
-
- if ( rsc )
- ctx->rx_seq = pn_to_u64 ( rsc );
-
- cipher_setkey ( &aes_algorithm, ctx->aes_ctx, key, keylen );
-
- return 0;
- }
-
-
- /**
- * Encrypt or decrypt data stream using AES in Counter mode
- *
- * @v ctx CCMP cryptosystem context
- * @v nonce Nonce value, 13 bytes
- * @v srcv Data to encrypt or decrypt
- * @v len Number of bytes pointed to by @a src
- * @v msrcv MIC value to encrypt or decrypt (may be NULL)
- * @ret destv Encrypted or decrypted data
- * @ret mdestv Encrypted or decrypted MIC value
- *
- * This assumes CCMP parameters of L=2 and M=8. The algorithm is
- * defined in RFC 3610.
- */
- static void ccmp_ctr_xor ( struct ccmp_ctx *ctx, const void *nonce,
- const void *srcv, void *destv, int len,
- const void *msrcv, void *mdestv )
- {
- u8 A[16], S[16];
- u16 ctr;
- int i;
- const u8 *src = srcv, *msrc = msrcv;
- u8 *dest = destv, *mdest = mdestv;
-
- A[0] = 0x01; /* flags, L' = L - 1 = 1, other bits rsvd */
- memcpy ( A + 1, nonce, CCMP_NONCE_LEN );
-
- if ( msrcv ) {
- A[14] = A[15] = 0;
-
- cipher_encrypt ( &aes_algorithm, ctx->aes_ctx, A, S, 16 );
-
- for ( i = 0; i < 8; i++ ) {
- *mdest++ = *msrc++ ^ S[i];
- }
- }
-
- for ( ctr = 1 ;; ctr++ ) {
- A[14] = ctr >> 8;
- A[15] = ctr & 0xFF;
-
- cipher_encrypt ( &aes_algorithm, ctx->aes_ctx, A, S, 16 );
-
- for ( i = 0; i < len && i < 16; i++ )
- *dest++ = *src++ ^ S[i];
-
- if ( len <= 16 )
- break; /* we're done */
-
- len -= 16;
- }
- }
-
-
- /**
- * Advance one block in CBC-MAC calculation
- *
- * @v aes_ctx AES encryption context with key set
- * @v B Cleartext block to incorporate (16 bytes)
- * @v X Previous ciphertext block (16 bytes)
- * @ret B Clobbered
- * @ret X New ciphertext block (16 bytes)
- *
- * This function does X := E[key] ( X ^ B ).
- */
- static void ccmp_feed_cbc_mac ( void *aes_ctx, u8 *B, u8 *X )
- {
- int i;
- for ( i = 0; i < 16; i++ )
- B[i] ^= X[i];
- cipher_encrypt ( &aes_algorithm, aes_ctx, B, X, 16 );
- }
-
-
- /**
- * Calculate MIC on plaintext data using CBC-MAC
- *
- * @v ctx CCMP cryptosystem context
- * @v nonce Nonce value, 13 bytes
- * @v data Data to calculate MIC over
- * @v datalen Length of @a data
- * @v aad Additional authentication data, for MIC but not encryption
- * @ret mic MIC value (unencrypted), 8 bytes
- *
- * @a aadlen is assumed to be 22 bytes long, as it always is for
- * 802.11 use when transmitting non-QoS, not-between-APs frames (the
- * only type we deal with).
- */
- static void ccmp_cbc_mac ( struct ccmp_ctx *ctx, const void *nonce,
- const void *data, u16 datalen,
- const void *aad, void *mic )
- {
- u8 X[16], B[16];
-
- /* Zeroth block: flags, nonce, length */
-
- /* Rsv AAD - M'- - L'-
- * 0 1 0 1 1 0 0 1 for an 8-byte MAC and 2-byte message length
- */
- B[0] = 0x59;
- memcpy ( B + 1, nonce, CCMP_NONCE_LEN );
- B[14] = datalen >> 8;
- B[15] = datalen & 0xFF;
-
- cipher_encrypt ( &aes_algorithm, ctx->aes_ctx, B, X, 16 );
-
- /* First block: AAD length field and 14 bytes of AAD */
- B[0] = 0;
- B[1] = CCMP_AAD_LEN;
- memcpy ( B + 2, aad, 14 );
-
- ccmp_feed_cbc_mac ( ctx->aes_ctx, B, X );
-
- /* Second block: Remaining 8 bytes of AAD, 8 bytes zero pad */
- memcpy ( B, aad + 14, 8 );
- memset ( B + 8, 0, 8 );
-
- ccmp_feed_cbc_mac ( ctx->aes_ctx, B, X );
-
- /* Message blocks */
- while ( datalen ) {
- if ( datalen >= 16 ) {
- memcpy ( B, data, 16 );
- datalen -= 16;
- } else {
- memcpy ( B, data, datalen );
- memset ( B + datalen, 0, 16 - datalen );
- datalen = 0;
- }
-
- ccmp_feed_cbc_mac ( ctx->aes_ctx, B, X );
-
- data += 16;
- }
-
- /* Get MIC from final value of X */
- memcpy ( mic, X, 8 );
- }
-
-
- /**
- * Encapsulate and encrypt a packet using CCMP
- *
- * @v crypto CCMP cryptosystem
- * @v iob I/O buffer containing cleartext packet
- * @ret eiob I/O buffer containing encrypted packet
- */
- struct io_buffer * ccmp_encrypt ( struct net80211_crypto *crypto,
- struct io_buffer *iob )
- {
- struct ccmp_ctx *ctx = crypto->priv;
- struct ieee80211_frame *hdr = iob->data;
- struct io_buffer *eiob;
- const int hdrlen = IEEE80211_TYP_FRAME_HEADER_LEN;
- int datalen = iob_len ( iob ) - hdrlen;
- struct ccmp_head head;
- struct ccmp_nonce nonce;
- struct ccmp_aad aad;
- u8 mic[8], tx_pn[6];
- void *edata, *emic;
-
- ctx->tx_seq++;
- u64_to_pn ( ctx->tx_seq, tx_pn, PN_LSB );
-
- /* Allocate memory */
- eiob = alloc_iob ( iob_len ( iob ) + CCMP_HEAD_LEN + CCMP_MIC_LEN );
- if ( ! eiob )
- return NULL;
-
- /* Copy frame header */
- memcpy ( iob_put ( eiob, hdrlen ), iob->data, hdrlen );
- hdr = eiob->data;
- hdr->fc |= IEEE80211_FC_PROTECTED;
-
- /* Fill in packet number and extended IV */
- memcpy ( head.pn_lo, tx_pn, 2 );
- memcpy ( head.pn_hi, tx_pn + 2, 4 );
- head.kid = 0x20; /* have Extended IV, key ID 0 */
- head._rsvd = 0;
- memcpy ( iob_put ( eiob, sizeof ( head ) ), &head, sizeof ( head ) );
-
- /* Form nonce */
- nonce.prio = 0;
- memcpy ( nonce.a2, hdr->addr2, ETH_ALEN );
- u64_to_pn ( ctx->tx_seq, nonce.pn, PN_MSB );
-
- /* Form additional authentication data */
- aad.fc = hdr->fc & CCMP_AAD_FC_MASK;
- memcpy ( aad.a1, hdr->addr1, 3 * ETH_ALEN ); /* all 3 at once */
- aad.seq = hdr->seq & CCMP_AAD_SEQ_MASK;
-
- /* Calculate MIC over the data */
- ccmp_cbc_mac ( ctx, &nonce, iob->data + hdrlen, datalen, &aad, mic );
-
- /* Copy and encrypt data and MIC */
- edata = iob_put ( eiob, datalen );
- emic = iob_put ( eiob, CCMP_MIC_LEN );
- ccmp_ctr_xor ( ctx, &nonce,
- iob->data + hdrlen, edata, datalen,
- mic, emic );
-
- /* Done! */
- DBGC2 ( ctx, "WPA-CCMP %p: encrypted packet %p -> %p\n", ctx,
- iob, eiob );
-
- return eiob;
- }
-
- /**
- * Decrypt a packet using CCMP
- *
- * @v crypto CCMP cryptosystem
- * @v eiob I/O buffer containing encrypted packet
- * @ret iob I/O buffer containing cleartext packet
- */
- static struct io_buffer * ccmp_decrypt ( struct net80211_crypto *crypto,
- struct io_buffer *eiob )
- {
- struct ccmp_ctx *ctx = crypto->priv;
- struct ieee80211_frame *hdr;
- struct io_buffer *iob;
- const int hdrlen = IEEE80211_TYP_FRAME_HEADER_LEN;
- int datalen = iob_len ( eiob ) - hdrlen - CCMP_HEAD_LEN - CCMP_MIC_LEN;
- struct ccmp_head *head;
- struct ccmp_nonce nonce;
- struct ccmp_aad aad;
- u8 rx_pn[6], their_mic[8], our_mic[8];
-
- iob = alloc_iob ( hdrlen + datalen );
- if ( ! iob )
- return NULL;
-
- /* Copy frame header */
- memcpy ( iob_put ( iob, hdrlen ), eiob->data, hdrlen );
- hdr = iob->data;
- hdr->fc &= ~IEEE80211_FC_PROTECTED;
-
- /* Check and update RX packet number */
- head = eiob->data + hdrlen;
- memcpy ( rx_pn, head->pn_lo, 2 );
- memcpy ( rx_pn + 2, head->pn_hi, 4 );
-
- if ( pn_to_u64 ( rx_pn ) <= ctx->rx_seq ) {
- DBGC ( ctx, "WPA-CCMP %p: packet received out of order "
- "(%012llx <= %012llx)\n", ctx, pn_to_u64 ( rx_pn ),
- ctx->rx_seq );
- free_iob ( iob );
- return NULL;
- }
-
- ctx->rx_seq = pn_to_u64 ( rx_pn );
- DBGC2 ( ctx, "WPA-CCMP %p: RX packet number %012llx\n", ctx, ctx->rx_seq );
-
- /* Form nonce */
- nonce.prio = 0;
- memcpy ( nonce.a2, hdr->addr2, ETH_ALEN );
- u64_to_pn ( ctx->rx_seq, nonce.pn, PN_MSB );
-
- /* Form additional authentication data */
- aad.fc = ( hdr->fc & CCMP_AAD_FC_MASK ) | IEEE80211_FC_PROTECTED;
- memcpy ( aad.a1, hdr->addr1, 3 * ETH_ALEN ); /* all 3 at once */
- aad.seq = hdr->seq & CCMP_AAD_SEQ_MASK;
-
- /* Copy-decrypt data and MIC */
- ccmp_ctr_xor ( ctx, &nonce, eiob->data + hdrlen + sizeof ( *head ),
- iob_put ( iob, datalen ), datalen,
- eiob->tail - CCMP_MIC_LEN, their_mic );
-
- /* Check MIC */
- ccmp_cbc_mac ( ctx, &nonce, iob->data + hdrlen, datalen, &aad,
- our_mic );
-
- if ( memcmp ( their_mic, our_mic, CCMP_MIC_LEN ) != 0 ) {
- DBGC2 ( ctx, "WPA-CCMP %p: MIC failure\n", ctx );
- free_iob ( iob );
- return NULL;
- }
-
- DBGC2 ( ctx, "WPA-CCMP %p: decrypted packet %p -> %p\n", ctx,
- eiob, iob );
-
- return iob;
- }
-
-
- /** CCMP cryptosystem */
- struct net80211_crypto ccmp_crypto __net80211_crypto = {
- .algorithm = NET80211_CRYPT_CCMP,
- .init = ccmp_init,
- .encrypt = ccmp_encrypt,
- .decrypt = ccmp_decrypt,
- .priv_len = sizeof ( struct ccmp_ctx ),
- };
-
-
-
-
- /**
- * Calculate HMAC-SHA1 MIC for EAPOL-Key frame
- *
- * @v kck Key Confirmation Key, 16 bytes
- * @v msg Message to calculate MIC over
- * @v len Number of bytes to calculate MIC over
- * @ret mic Calculated MIC, 16 bytes long
- */
- static void ccmp_kie_mic ( const void *kck, const void *msg, size_t len,
- void *mic )
- {
- u8 sha1_ctx[SHA1_CTX_SIZE];
- u8 kckb[16];
- u8 hash[SHA1_SIZE];
- size_t kck_len = 16;
-
- memcpy ( kckb, kck, kck_len );
-
- hmac_init ( &sha1_algorithm, sha1_ctx, kckb, &kck_len );
- hmac_update ( &sha1_algorithm, sha1_ctx, msg, len );
- hmac_final ( &sha1_algorithm, sha1_ctx, kckb, &kck_len, hash );
-
- memcpy ( mic, hash, 16 );
- }
-
- /**
- * Decrypt key data in EAPOL-Key frame
- *
- * @v kek Key Encryption Key, 16 bytes
- * @v iv Initialisation vector, 16 bytes (unused)
- * @v msg Message to decrypt
- * @v len Length of message
- * @ret msg Decrypted message in place of original
- * @ret len Adjusted downward for 8 bytes of overhead
- * @ret rc Return status code
- *
- * The returned message may still contain padding of 0xDD followed by
- * zero or more 0x00 octets. It is impossible to remove the padding
- * without parsing the IEs in the packet (another design decision that
- * tends to make one question the 802.11i committee's intelligence...)
- */
- static int ccmp_kie_decrypt ( const void *kek, const void *iv __unused,
- void *msg, u16 *len )
- {
- if ( *len % 8 != 0 )
- return -EINVAL;
-
- if ( aes_unwrap ( kek, msg, msg, *len / 8 - 1 ) != 0 )
- return -EINVAL;
-
- *len -= 8;
-
- return 0;
- }
-
- /** CCMP-style key integrity and encryption handler */
- struct wpa_kie ccmp_kie __wpa_kie = {
- .version = EAPOL_KEY_VERSION_WPA2,
- .mic = ccmp_kie_mic,
- .decrypt = ccmp_kie_decrypt,
- };
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