--- /dev/null
+/*
+ * Ultra Wide Band
+ * AES-128 CCM Encryption
+ *
+ * Copyright (C) 2007 Intel Corporation
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * 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.
+ *
+ * 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.
+ *
+ *
+ * We don't do any encryption here; we use the Linux Kernel's AES-128
+ * crypto modules to construct keys and payload blocks in a way
+ * defined by WUSB1.0[6]. Check the erratas, as typos are are patched
+ * there.
+ *
+ * Thanks a zillion to John Keys for his help and clarifications over
+ * the designed-by-a-committee text.
+ *
+ * So the idea is that there is this basic Pseudo-Random-Function
+ * defined in WUSB1.0[6.5] which is the core of everything. It works
+ * by tweaking some blocks, AES crypting them and then xoring
+ * something else with them (this seems to be called CBC(AES) -- can
+ * you tell I know jack about crypto?). So we just funnel it into the
+ * Linux Crypto API.
+ *
+ * We leave a crypto test module so we can verify that vectors match,
+ * every now and then.
+ *
+ * Block size: 16 bytes -- AES seems to do things in 'block sizes'. I
+ * am learning a lot...
+ *
+ * Conveniently, some data structures that need to be
+ * funneled through AES are...16 bytes in size!
+ */
+
+#include <linux/crypto.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/uwb.h>
+#include <linux/slab.h>
+#include <linux/usb/wusb.h>
+#include <linux/scatterlist.h>
+
+static int debug_crypto_verify = 0;
+
+module_param(debug_crypto_verify, int, 0);
+MODULE_PARM_DESC(debug_crypto_verify, "verify the key generation algorithms");
+
+static void wusb_key_dump(const void *buf, size_t len)
+{
+ print_hex_dump(KERN_ERR, " ", DUMP_PREFIX_OFFSET, 16, 1,
+ buf, len, 0);
+}
+
+/*
+ * Block of data, as understood by AES-CCM
+ *
+ * The code assumes this structure is nothing but a 16 byte array
+ * (packed in a struct to avoid common mess ups that I usually do with
+ * arrays and enforcing type checking).
+ */
+struct aes_ccm_block {
+ u8 data[16];
+} __attribute__((packed));
+
+/*
+ * Counter-mode Blocks (WUSB1.0[6.4])
+ *
+ * According to CCM (or so it seems), for the purpose of calculating
+ * the MIC, the message is broken in N counter-mode blocks, B0, B1,
+ * ... BN.
+ *
+ * B0 contains flags, the CCM nonce and l(m).
+ *
+ * B1 contains l(a), the MAC header, the encryption offset and padding.
+ *
+ * If EO is nonzero, additional blocks are built from payload bytes
+ * until EO is exhausted (FIXME: padding to 16 bytes, I guess). The
+ * padding is not xmitted.
+ */
+
+/* WUSB1.0[T6.4] */
+struct aes_ccm_b0 {
+ u8 flags; /* 0x59, per CCM spec */
+ struct aes_ccm_nonce ccm_nonce;
+ __be16 lm;
+} __attribute__((packed));
+
+/* WUSB1.0[T6.5] */
+struct aes_ccm_b1 {
+ __be16 la;
+ u8 mac_header[10];
+ __le16 eo;
+ u8 security_reserved; /* This is always zero */
+ u8 padding; /* 0 */
+} __attribute__((packed));
+
+/*
+ * Encryption Blocks (WUSB1.0[6.4.4])
+ *
+ * CCM uses Ax blocks to generate a keystream with which the MIC and
+ * the message's payload are encoded. A0 always encrypts/decrypts the
+ * MIC. Ax (x>0) are used for the successive payload blocks.
+ *
+ * The x is the counter, and is increased for each block.
+ */
+struct aes_ccm_a {
+ u8 flags; /* 0x01, per CCM spec */
+ struct aes_ccm_nonce ccm_nonce;
+ __be16 counter; /* Value of x */
+} __attribute__((packed));
+
+static void bytewise_xor(void *_bo, const void *_bi1, const void *_bi2,
+ size_t size)
+{
+ u8 *bo = _bo;
+ const u8 *bi1 = _bi1, *bi2 = _bi2;
+ size_t itr;
+ for (itr = 0; itr < size; itr++)
+ bo[itr] = bi1[itr] ^ bi2[itr];
+}
+
+/*
+ * CC-MAC function WUSB1.0[6.5]
+ *
+ * Take a data string and produce the encrypted CBC Counter-mode MIC
+ *
+ * Note the names for most function arguments are made to (more or
+ * less) match those used in the pseudo-function definition given in
+ * WUSB1.0[6.5].
+ *
+ * @tfm_cbc: CBC(AES) blkcipher handle (initialized)
+ *
+ * @tfm_aes: AES cipher handle (initialized)
+ *
+ * @mic: buffer for placing the computed MIC (Message Integrity
+ * Code). This is exactly 8 bytes, and we expect the buffer to
+ * be at least eight bytes in length.
+ *
+ * @key: 128 bit symmetric key
+ *
+ * @n: CCM nonce
+ *
+ * @a: ASCII string, 14 bytes long (I guess zero padded if needed;
+ * we use exactly 14 bytes).
+ *
+ * @b: data stream to be processed; cannot be a global or const local
+ * (will confuse the scatterlists)
+ *
+ * @blen: size of b...
+ *
+ * Still not very clear how this is done, but looks like this: we
+ * create block B0 (as WUSB1.0[6.5] says), then we AES-crypt it with
+ * @key. We bytewise xor B0 with B1 (1) and AES-crypt that. Then we
+ * take the payload and divide it in blocks (16 bytes), xor them with
+ * the previous crypto result (16 bytes) and crypt it, repeat the next
+ * block with the output of the previous one, rinse wash (I guess this
+ * is what AES CBC mode means...but I truly have no idea). So we use
+ * the CBC(AES) blkcipher, that does precisely that. The IV (Initial
+ * Vector) is 16 bytes and is set to zero, so
+ *
+ * See rfc3610. Linux crypto has a CBC implementation, but the
+ * documentation is scarce, to say the least, and the example code is
+ * so intricated that is difficult to understand how things work. Most
+ * of this is guess work -- bite me.
+ *
+ * (1) Created as 6.5 says, again, using as l(a) 'Blen + 14', and
+ * using the 14 bytes of @a to fill up
+ * b1.{mac_header,e0,security_reserved,padding}.
+ *
+ * NOTE: The definition of l(a) in WUSB1.0[6.5] vs the definition of
+ * l(m) is orthogonal, they bear no relationship, so it is not
+ * in conflict with the parameter's relation that
+ * WUSB1.0[6.4.2]) defines.
+ *
+ * NOTE: WUSB1.0[A.1]: Host Nonce is missing a nibble? (1e); fixed in
+ * first errata released on 2005/07.
+ *
+ * NOTE: we need to clean IV to zero at each invocation to make sure
+ * we start with a fresh empty Initial Vector, so that the CBC
+ * works ok.
+ *
+ * NOTE: blen is not aligned to a block size, we'll pad zeros, that's
+ * what sg[4] is for. Maybe there is a smarter way to do this.
+ */
+static int wusb_ccm_mac(struct crypto_blkcipher *tfm_cbc,
+ struct crypto_cipher *tfm_aes, void *mic,
+ const struct aes_ccm_nonce *n,
+ const struct aes_ccm_label *a, const void *b,
+ size_t blen)
+{
+ int result = 0;
+ struct blkcipher_desc desc;
+ struct aes_ccm_b0 b0;
+ struct aes_ccm_b1 b1;
+ struct aes_ccm_a ax;
+ struct scatterlist sg[4], sg_dst;
+ void *iv, *dst_buf;
+ size_t ivsize, dst_size;
+ const u8 bzero[16] = { 0 };
+ size_t zero_padding;
+
+ /*
+ * These checks should be compile time optimized out
+ * ensure @a fills b1's mac_header and following fields
+ */
+ WARN_ON(sizeof(*a) != sizeof(b1) - sizeof(b1.la));
+ WARN_ON(sizeof(b0) != sizeof(struct aes_ccm_block));
+ WARN_ON(sizeof(b1) != sizeof(struct aes_ccm_block));
+ WARN_ON(sizeof(ax) != sizeof(struct aes_ccm_block));
+
+ result = -ENOMEM;
+ zero_padding = blen % sizeof(struct aes_ccm_block);
+ if (zero_padding)
+ zero_padding = sizeof(struct aes_ccm_block) - zero_padding;
+ dst_size = blen + sizeof(b0) + sizeof(b1) + zero_padding;
+ dst_buf = kzalloc(dst_size, GFP_KERNEL);
+ if (dst_buf == NULL) {
+ printk(KERN_ERR "E: can't alloc destination buffer\n");
+ goto error_dst_buf;
+ }
+
+ iv = crypto_blkcipher_crt(tfm_cbc)->iv;
+ ivsize = crypto_blkcipher_ivsize(tfm_cbc);
+ memset(iv, 0, ivsize);
+
+ /* Setup B0 */
+ b0.flags = 0x59; /* Format B0 */
+ b0.ccm_nonce = *n;
+ b0.lm = cpu_to_be16(0); /* WUSB1.0[6.5] sez l(m) is 0 */
+
+ /* Setup B1
+ *
+ * The WUSB spec is anything but clear! WUSB1.0[6.5]
+ * says that to initialize B1 from A with 'l(a) = blen +
+ * 14'--after clarification, it means to use A's contents
+ * for MAC Header, EO, sec reserved and padding.
+ */
+ b1.la = cpu_to_be16(blen + 14);
+ memcpy(&b1.mac_header, a, sizeof(*a));
+
+ sg_init_table(sg, ARRAY_SIZE(sg));
+ sg_set_buf(&sg[0], &b0, sizeof(b0));
+ sg_set_buf(&sg[1], &b1, sizeof(b1));
+ sg_set_buf(&sg[2], b, blen);
+ /* 0 if well behaved :) */
+ sg_set_buf(&sg[3], bzero, zero_padding);
+ sg_init_one(&sg_dst, dst_buf, dst_size);
+
+ desc.tfm = tfm_cbc;
+ desc.flags = 0;
+ result = crypto_blkcipher_encrypt(&desc, &sg_dst, sg, dst_size);
+ if (result < 0) {
+ printk(KERN_ERR "E: can't compute CBC-MAC tag (MIC): %d\n",
+ result);
+ goto error_cbc_crypt;
+ }
+
+ /* Now we crypt the MIC Tag (*iv) with Ax -- values per WUSB1.0[6.5]
+ * The procedure is to AES crypt the A0 block and XOR the MIC
+ * Tag against it; we only do the first 8 bytes and place it
+ * directly in the destination buffer.
+ *
+ * POS Crypto API: size is assumed to be AES's block size.
+ * Thanks for documenting it -- tip taken from airo.c
+ */
+ ax.flags = 0x01; /* as per WUSB 1.0 spec */
+ ax.ccm_nonce = *n;
+ ax.counter = 0;
+ crypto_cipher_encrypt_one(tfm_aes, (void *)&ax, (void *)&ax);
+ bytewise_xor(mic, &ax, iv, 8);
+ result = 8;
+error_cbc_crypt:
+ kfree(dst_buf);
+error_dst_buf:
+ return result;
+}
+
+/*
+ * WUSB Pseudo Random Function (WUSB1.0[6.5])
+ *
+ * @b: buffer to the source data; cannot be a global or const local
+ * (will confuse the scatterlists)
+ */
+ssize_t wusb_prf(void *out, size_t out_size,
+ const u8 key[16], const struct aes_ccm_nonce *_n,
+ const struct aes_ccm_label *a,
+ const void *b, size_t blen, size_t len)
+{
+ ssize_t result, bytes = 0, bitr;
+ struct aes_ccm_nonce n = *_n;
+ struct crypto_blkcipher *tfm_cbc;
+ struct crypto_cipher *tfm_aes;
+ u64 sfn = 0;
+ __le64 sfn_le;
+
+ tfm_cbc = crypto_alloc_blkcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(tfm_cbc)) {
+ result = PTR_ERR(tfm_cbc);
+ printk(KERN_ERR "E: can't load CBC(AES): %d\n", (int)result);
+ goto error_alloc_cbc;
+ }
+ result = crypto_blkcipher_setkey(tfm_cbc, key, 16);
+ if (result < 0) {
+ printk(KERN_ERR "E: can't set CBC key: %d\n", (int)result);
+ goto error_setkey_cbc;
+ }
+
+ tfm_aes = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(tfm_aes)) {
+ result = PTR_ERR(tfm_aes);
+ printk(KERN_ERR "E: can't load AES: %d\n", (int)result);
+ goto error_alloc_aes;
+ }
+ result = crypto_cipher_setkey(tfm_aes, key, 16);
+ if (result < 0) {
+ printk(KERN_ERR "E: can't set AES key: %d\n", (int)result);
+ goto error_setkey_aes;
+ }
+
+ for (bitr = 0; bitr < (len + 63) / 64; bitr++) {
+ sfn_le = cpu_to_le64(sfn++);
+ memcpy(&n.sfn, &sfn_le, sizeof(n.sfn)); /* n.sfn++... */
+ result = wusb_ccm_mac(tfm_cbc, tfm_aes, out + bytes,
+ &n, a, b, blen);
+ if (result < 0)
+ goto error_ccm_mac;
+ bytes += result;
+ }
+ result = bytes;
+error_ccm_mac:
+error_setkey_aes:
+ crypto_free_cipher(tfm_aes);
+error_alloc_aes:
+error_setkey_cbc:
+ crypto_free_blkcipher(tfm_cbc);
+error_alloc_cbc:
+ return result;
+}
+
+/* WUSB1.0[A.2] test vectors */
+static const u8 stv_hsmic_key[16] = {
+ 0x4b, 0x79, 0xa3, 0xcf, 0xe5, 0x53, 0x23, 0x9d,
+ 0xd7, 0xc1, 0x6d, 0x1c, 0x2d, 0xab, 0x6d, 0x3f
+};
+
+static const struct aes_ccm_nonce stv_hsmic_n = {
+ .sfn = { 0 },
+ .tkid = { 0x76, 0x98, 0x01, },
+ .dest_addr = { .data = { 0xbe, 0x00 } },
+ .src_addr = { .data = { 0x76, 0x98 } },
+};
+
+/*
+ * Out-of-band MIC Generation verification code
+ *
+ */
+static int wusb_oob_mic_verify(void)
+{
+ int result;
+ u8 mic[8];
+ /* WUSB1.0[A.2] test vectors
+ *
+ * Need to keep it in the local stack as GCC 4.1.3something
+ * messes up and generates noise.
+ */
+ struct usb_handshake stv_hsmic_hs = {
+ .bMessageNumber = 2,
+ .bStatus = 00,
+ .tTKID = { 0x76, 0x98, 0x01 },
+ .bReserved = 00,
+ .CDID = { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35,
+ 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
+ 0x3c, 0x3d, 0x3e, 0x3f },
+ .nonce = { 0x20, 0x21, 0x22, 0x23, 0x24, 0x25,
+ 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
+ 0x2c, 0x2d, 0x2e, 0x2f },
+ .MIC = { 0x75, 0x6a, 0x97, 0x51, 0x0c, 0x8c,
+ 0x14, 0x7b } ,
+ };
+ size_t hs_size;
+
+ result = wusb_oob_mic(mic, stv_hsmic_key, &stv_hsmic_n, &stv_hsmic_hs);
+ if (result < 0)
+ printk(KERN_ERR "E: WUSB OOB MIC test: failed: %d\n", result);
+ else if (memcmp(stv_hsmic_hs.MIC, mic, sizeof(mic))) {
+ printk(KERN_ERR "E: OOB MIC test: "
+ "mismatch between MIC result and WUSB1.0[A2]\n");
+ hs_size = sizeof(stv_hsmic_hs) - sizeof(stv_hsmic_hs.MIC);
+ printk(KERN_ERR "E: Handshake2 in: (%zu bytes)\n", hs_size);
+ wusb_key_dump(&stv_hsmic_hs, hs_size);
+ printk(KERN_ERR "E: CCM Nonce in: (%zu bytes)\n",
+ sizeof(stv_hsmic_n));
+ wusb_key_dump(&stv_hsmic_n, sizeof(stv_hsmic_n));
+ printk(KERN_ERR "E: MIC out:\n");
+ wusb_key_dump(mic, sizeof(mic));
+ printk(KERN_ERR "E: MIC out (from WUSB1.0[A.2]):\n");
+ wusb_key_dump(stv_hsmic_hs.MIC, sizeof(stv_hsmic_hs.MIC));
+ result = -EINVAL;
+ } else
+ result = 0;
+ return result;
+}
+
+/*
+ * Test vectors for Key derivation
+ *
+ * These come from WUSB1.0[6.5.1], the vectors in WUSB1.0[A.1]
+ * (errata corrected in 2005/07).
+ */
+static const u8 stv_key_a1[16] __attribute__ ((__aligned__(4))) = {
+ 0xf0, 0xe1, 0xd2, 0xc3, 0xb4, 0xa5, 0x96, 0x87,
+ 0x78, 0x69, 0x5a, 0x4b, 0x3c, 0x2d, 0x1e, 0x0f
+};
+
+static const struct aes_ccm_nonce stv_keydvt_n_a1 = {
+ .sfn = { 0 },
+ .tkid = { 0x76, 0x98, 0x01, },
+ .dest_addr = { .data = { 0xbe, 0x00 } },
+ .src_addr = { .data = { 0x76, 0x98 } },
+};
+
+static const struct wusb_keydvt_out stv_keydvt_out_a1 = {
+ .kck = {
+ 0x4b, 0x79, 0xa3, 0xcf, 0xe5, 0x53, 0x23, 0x9d,
+ 0xd7, 0xc1, 0x6d, 0x1c, 0x2d, 0xab, 0x6d, 0x3f
+ },
+ .ptk = {
+ 0xc8, 0x70, 0x62, 0x82, 0xb6, 0x7c, 0xe9, 0x06,
+ 0x7b, 0xc5, 0x25, 0x69, 0xf2, 0x36, 0x61, 0x2d
+ }
+};
+
+/*
+ * Performa a test to make sure we match the vectors defined in
+ * WUSB1.0[A.1](Errata2006/12)
+ */
+static int wusb_key_derive_verify(void)
+{
+ int result = 0;
+ struct wusb_keydvt_out keydvt_out;
+ /* These come from WUSB1.0[A.1] + 2006/12 errata
+ * NOTE: can't make this const or global -- somehow it seems
+ * the scatterlists for crypto get confused and we get
+ * bad data. There is no doc on this... */
+ struct wusb_keydvt_in stv_keydvt_in_a1 = {
+ .hnonce = {
+ 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+ 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
+ },
+ .dnonce = {
+ 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+ 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f
+ }
+ };
+
+ result = wusb_key_derive(&keydvt_out, stv_key_a1, &stv_keydvt_n_a1,
+ &stv_keydvt_in_a1);
+ if (result < 0)
+ printk(KERN_ERR "E: WUSB key derivation test: "
+ "derivation failed: %d\n", result);
+ if (memcmp(&stv_keydvt_out_a1, &keydvt_out, sizeof(keydvt_out))) {
+ printk(KERN_ERR "E: WUSB key derivation test: "
+ "mismatch between key derivation result "
+ "and WUSB1.0[A1] Errata 2006/12\n");
+ printk(KERN_ERR "E: keydvt in: key\n");
+ wusb_key_dump(stv_key_a1, sizeof(stv_key_a1));
+ printk(KERN_ERR "E: keydvt in: nonce\n");
+ wusb_key_dump( &stv_keydvt_n_a1, sizeof(stv_keydvt_n_a1));
+ printk(KERN_ERR "E: keydvt in: hnonce & dnonce\n");
+ wusb_key_dump(&stv_keydvt_in_a1, sizeof(stv_keydvt_in_a1));
+ printk(KERN_ERR "E: keydvt out: KCK\n");
+ wusb_key_dump(&keydvt_out.kck, sizeof(keydvt_out.kck));
+ printk(KERN_ERR "E: keydvt out: PTK\n");
+ wusb_key_dump(&keydvt_out.ptk, sizeof(keydvt_out.ptk));
+ result = -EINVAL;
+ } else
+ result = 0;
+ return result;
+}
+
+/*
+ * Initialize crypto system
+ *
+ * FIXME: we do nothing now, other than verifying. Later on we'll
+ * cache the encryption stuff, so that's why we have a separate init.
+ */
+int wusb_crypto_init(void)
+{
+ int result;
+
+ if (debug_crypto_verify) {
+ result = wusb_key_derive_verify();
+ if (result < 0)
+ return result;
+ return wusb_oob_mic_verify();
+ }
+ return 0;
+}
+
+void wusb_crypto_exit(void)
+{
+ /* FIXME: free cached crypto transforms */
+}
Code Review / kvmfornfv.git / blobdiff