wusb: add the Wireless USB core (security)

Add the WUSB security (authentication) code.
Signed-off-by: NDavid Vrabel <david.vrabel@csr.com>

drivers/usb/wusbcore/crypto.c

+/*
+ * 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/usb/wusb.h>
+#include <linux/scatterlist.h>
+#define D_LOCAL 0
+#include <linux/uwb/debug.h>
+
+
+/*
+ * 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 exahusted (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 sucesive 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 definiton 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;
+
+	d_fnstart(3, NULL, "(tfm_cbc %p, tfm_aes %p, mic %p, "
+		  "n %p, a %p, b %p, blen %zu)\n",
+		  tfm_cbc, tfm_aes, mic, n, a, b, blen);
+	/*
+	 * 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 = sizeof(struct aes_ccm_block)
+		- blen % sizeof(struct aes_ccm_block);
+	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));
+
+	d_printf(4, NULL, "I: B0 (%zu bytes)\n", sizeof(b0));
+	d_dump(4, NULL, &b0, sizeof(b0));
+	d_printf(4, NULL, "I: B1 (%zu bytes)\n", sizeof(b1));
+	d_dump(4, NULL, &b1, sizeof(b1));
+	d_printf(4, NULL, "I: B (%zu bytes)\n", blen);
+	d_dump(4, NULL, b, blen);
+	d_printf(4, NULL, "I: B 0-padding (%zu bytes)\n", zero_padding);
+	d_printf(4, NULL, "D: IV before crypto (%zu)\n", ivsize);
+	d_dump(4, NULL, iv, ivsize);
+
+	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;
+	}
+	d_printf(4, NULL, "D: MIC tag\n");
+	d_dump(4, NULL, iv, ivsize);
+
+	/* 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 agains 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);
+	d_printf(4, NULL, "D: CTR[MIC]\n");
+	d_dump(4, NULL, &ax, 8);
+	d_printf(4, NULL, "D: CCM-MIC tag\n");
+	d_dump(4, NULL, mic, 8);
+	result = 8;
+error_cbc_crypt:
+	kfree(dst_buf);
+error_dst_buf:
+	d_fnend(3, NULL, "(tfm_cbc %p, tfm_aes %p, mic %p, "
+		"n %p, a %p, b %p, blen %zu)\n",
+		tfm_cbc, tfm_aes, mic, n, a, b, blen);
+	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;
+
+	d_fnstart(3, NULL, "(out %p, out_size %zu, key %p, _n %p, "
+		  "a %p, b %p, blen %zu, len %zu)\n", out, out_size,
+		  key, _n, a, b, blen, len);
+
+	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:
+	d_fnend(3, NULL, "(out %p, out_size %zu, key %p, _n %p, "
+		"a %p, b %p, blen %zu, len %zu) = %d\n", out, out_size,
+		key, _n, a, b, blen, len, (int)bytes);
+	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);
+		dump_bytes(NULL, &stv_hsmic_hs, hs_size);
+		printk(KERN_ERR "E: CCM Nonce in: (%zu bytes)\n",
+		       sizeof(stv_hsmic_n));
+		dump_bytes(NULL, &stv_hsmic_n, sizeof(stv_hsmic_n));
+		printk(KERN_ERR "E: MIC out:\n");
+		dump_bytes(NULL, mic, sizeof(mic));
+		printk(KERN_ERR "E: MIC out (from WUSB1.0[A.2]):\n");
+		dump_bytes(NULL, 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 (%zu bytes)\n",
+		       sizeof(stv_key_a1));
+		dump_bytes(NULL, stv_key_a1, sizeof(stv_key_a1));
+		printk(KERN_ERR "E: keydvt in: nonce (%zu bytes)\n",
+		       sizeof(stv_keydvt_n_a1));
+		dump_bytes(NULL, &stv_keydvt_n_a1, sizeof(stv_keydvt_n_a1));
+		printk(KERN_ERR "E: keydvt in: hnonce & dnonce (%zu bytes)\n",
+		       sizeof(stv_keydvt_in_a1));
+		dump_bytes(NULL, &stv_keydvt_in_a1, sizeof(stv_keydvt_in_a1));
+		printk(KERN_ERR "E: keydvt out: KCK\n");
+		dump_bytes(NULL, &keydvt_out.kck, sizeof(keydvt_out.kck));
+		printk(KERN_ERR "E: keydvt out: PTK\n");
+		dump_bytes(NULL, &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;
+
+	result = wusb_key_derive_verify();
+	if (result < 0)
+		return result;
+	return wusb_oob_mic_verify();
+}
+
+void wusb_crypto_exit(void)
+{
+	/* FIXME: free cached crypto transforms */
+}

drivers/usb/wusbcore/security.c

+/*
+ * Wireless USB Host Controller
+ * Security support: encryption enablement, etc
+ *
+ * Copyright (C) 2006 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.
+ *
+ *
+ * FIXME: docs
+ */
+#include <linux/types.h>
+#include <linux/usb/ch9.h>
+#include <linux/random.h>
+#include "wusbhc.h"
+
+/*
+ * DEBUG & SECURITY WARNING!!!!
+ *
+ * If you enable this past 1, the debug code will weaken the
+ * cryptographic safety of the system (on purpose, for debugging).
+ *
+ * Weaken means:
+ *   we print secret keys and intermediate values all the way,
+ */
+#undef D_LOCAL
+#define D_LOCAL 2
+#include <linux/uwb/debug.h>
+
+static void wusbhc_set_gtk_callback(struct urb *urb);
+static void wusbhc_gtk_rekey_done_work(struct work_struct *work);
+
+int wusbhc_sec_create(struct wusbhc *wusbhc)
+{
+	wusbhc->gtk.descr.bLength = sizeof(wusbhc->gtk.descr) + sizeof(wusbhc->gtk.data);
+	wusbhc->gtk.descr.bDescriptorType = USB_DT_KEY;
+	wusbhc->gtk.descr.bReserved = 0;
+
+	wusbhc->gtk_index = wusb_key_index(0, WUSB_KEY_INDEX_TYPE_GTK,
+					   WUSB_KEY_INDEX_ORIGINATOR_HOST);
+
+	INIT_WORK(&wusbhc->gtk_rekey_done_work, wusbhc_gtk_rekey_done_work);
+
+	return 0;
+}
+
+
+/* Called when the HC is destroyed */
+void wusbhc_sec_destroy(struct wusbhc *wusbhc)
+{
+}
+
+
+/**
+ * wusbhc_next_tkid - generate a new, currently unused, TKID
+ * @wusbhc:   the WUSB host controller
+ * @wusb_dev: the device whose PTK the TKID is for
+ *            (or NULL for a TKID for a GTK)
+ *
+ * The generated TKID consist of two parts: the device's authenicated
+ * address (or 0 or a GTK); and an incrementing number.  This ensures
+ * that TKIDs cannot be shared between devices and by the time the
+ * incrementing number wraps around the older TKIDs will no longer be
+ * in use (a maximum of two keys may be active at any one time).
+ */
+static u32 wusbhc_next_tkid(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
+{
+	u32 *tkid;
+	u32 addr;
+
+	if (wusb_dev == NULL) {
+		tkid = &wusbhc->gtk_tkid;
+		addr = 0;
+	} else {
+		tkid = &wusb_port_by_idx(wusbhc, wusb_dev->port_idx)->ptk_tkid;
+		addr = wusb_dev->addr & 0x7f;
+	}
+
+	*tkid = (addr << 8) | ((*tkid + 1) & 0xff);
+
+	return *tkid;
+}
+
+static void wusbhc_generate_gtk(struct wusbhc *wusbhc)
+{
+	const size_t key_size = sizeof(wusbhc->gtk.data);
+	u32 tkid;
+
+	tkid = wusbhc_next_tkid(wusbhc, NULL);
+
+	wusbhc->gtk.descr.tTKID[0] = (tkid >>  0) & 0xff;
+	wusbhc->gtk.descr.tTKID[1] = (tkid >>  8) & 0xff;
+	wusbhc->gtk.descr.tTKID[2] = (tkid >> 16) & 0xff;
+
+	get_random_bytes(wusbhc->gtk.descr.bKeyData, key_size);
+}
+
+/**
+ * wusbhc_sec_start - start the security management process
+ * @wusbhc: the WUSB host controller
+ *
+ * Generate and set an initial GTK on the host controller.
+ *
+ * Called when the HC is started.
+ */
+int wusbhc_sec_start(struct wusbhc *wusbhc)
+{
+	const size_t key_size = sizeof(wusbhc->gtk.data);
+	int result;
+
+	wusbhc_generate_gtk(wusbhc);
+
+	result = wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid,
+				 &wusbhc->gtk.descr.bKeyData, key_size);
+	if (result < 0)
+		dev_err(wusbhc->dev, "cannot set GTK for the host: %d\n",
+			result);
+
+	return result;
+}
+
+/**
+ * wusbhc_sec_stop - stop the security management process
+ * @wusbhc: the WUSB host controller
+ *
+ * Wait for any pending GTK rekeys to stop.
+ */
+void wusbhc_sec_stop(struct wusbhc *wusbhc)
+{
+	cancel_work_sync(&wusbhc->gtk_rekey_done_work);
+}
+
+
+/** @returns encryption type name */
+const char *wusb_et_name(u8 x)
+{
+	switch (x) {
+	case USB_ENC_TYPE_UNSECURE:	return "unsecure";
+	case USB_ENC_TYPE_WIRED:	return "wired";
+	case USB_ENC_TYPE_CCM_1:	return "CCM-1";
+	case USB_ENC_TYPE_RSA_1:	return "RSA-1";
+	default: 			return "unknown";
+	}
+}
+EXPORT_SYMBOL_GPL(wusb_et_name);
+
+/*
+ * Set the device encryption method
+ *
+ * We tell the device which encryption method to use; we do this when
+ * setting up the device's security.
+ */
+static int wusb_dev_set_encryption(struct usb_device *usb_dev, int value)
+{
+	int result;
+	struct device *dev = &usb_dev->dev;
+	struct wusb_dev *wusb_dev = usb_dev->wusb_dev;
+
+	if (value) {
+		value = wusb_dev->ccm1_etd.bEncryptionValue;
+	} else {
+		/* FIXME: should be wusb_dev->etd[UNSECURE].bEncryptionValue */
+		value = 0;
+	}
+	/* Set device's */
+	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
+			USB_REQ_SET_ENCRYPTION,
+			USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+			value, 0, NULL, 0, 1000 /* FIXME: arbitrary */);
+	if (result < 0)
+		dev_err(dev, "Can't set device's WUSB encryption to "
+			"%s (value %d): %d\n",
+			wusb_et_name(wusb_dev->ccm1_etd.bEncryptionType),
+			wusb_dev->ccm1_etd.bEncryptionValue,  result);
+	return result;
+}
+
+/*
+ * Set the GTK to be used by a device.
+ *
+ * The device must be authenticated.
+ */
+static int wusb_dev_set_gtk(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev)
+{
+	struct usb_device *usb_dev = wusb_dev->usb_dev;
+
+	return usb_control_msg(
+		usb_dev, usb_sndctrlpipe(usb_dev, 0),
+		USB_REQ_SET_DESCRIPTOR,
+		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+		USB_DT_KEY << 8 | wusbhc->gtk_index, 0,
+		&wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
+		1000);
+}
+
+
+/* FIXME: prototype for adding security */
+int wusb_dev_sec_add(struct wusbhc *wusbhc,
+		     struct usb_device *usb_dev, struct wusb_dev *wusb_dev)
+{
+	int result, bytes, secd_size;
+	struct device *dev = &usb_dev->dev;
+	struct usb_security_descriptor secd;
+	const struct usb_encryption_descriptor *etd, *ccm1_etd = NULL;
+	void *secd_buf;
+	const void *itr, *top;
+	char buf[64];
+
+	d_fnstart(3, dev, "(usb_dev %p, wusb_dev %p)\n", usb_dev, wusb_dev);
+	result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
+				    0, &secd, sizeof(secd));
+	if (result < sizeof(secd)) {
+		dev_err(dev, "Can't read security descriptor or "
+			"not enough data: %d\n", result);
+		goto error_secd;
+	}
+	secd_size = le16_to_cpu(secd.wTotalLength);
+	d_printf(5, dev, "got %d bytes of sec descriptor, total is %d\n",
+		 result, secd_size);
+	secd_buf = kmalloc(secd_size, GFP_KERNEL);
+	if (secd_buf == NULL) {
+		dev_err(dev, "Can't allocate space for security descriptors\n");
+		goto error_secd_alloc;
+	}
+	result = usb_get_descriptor(usb_dev, USB_DT_SECURITY,
+				    0, secd_buf, secd_size);
+	if (result < secd_size) {
+		dev_err(dev, "Can't read security descriptor or "
+			"not enough data: %d\n", result);
+		goto error_secd_all;
+	}
+	d_printf(5, dev, "got %d bytes of sec descriptors\n", result);
+	bytes = 0;
+	itr = secd_buf + sizeof(secd);
+	top = secd_buf + result;
+	while (itr < top) {
+		etd = itr;
+		if (top - itr < sizeof(*etd)) {
+			dev_err(dev, "BUG: bad device security descriptor; "
+				"not enough data (%zu vs %zu bytes left)\n",
+				top - itr, sizeof(*etd));
+			break;
+		}
+		if (etd->bLength < sizeof(*etd)) {
+			dev_err(dev, "BUG: bad device encryption descriptor; "
+				"descriptor is too short "
+				"(%u vs %zu needed)\n",
+				etd->bLength, sizeof(*etd));
+			break;
+		}
+		itr += etd->bLength;
+		bytes += snprintf(buf + bytes, sizeof(buf) - bytes,
+				  "%s (0x%02x/%02x) ",
+				  wusb_et_name(etd->bEncryptionType),
+				  etd->bEncryptionValue, etd->bAuthKeyIndex);
+		if (etd->bEncryptionType == USB_ENC_TYPE_CCM_1)
+			ccm1_etd = etd;
+	}
+	/* This code only supports CCM1 as of now. */
+	/* FIXME: user has to choose which sec mode to use?
+	 * In theory we want CCM */
+	if (ccm1_etd == NULL) {
+		dev_err(dev, "WUSB device doesn't support CCM1 encryption, "
+			"can't use!\n");
+		result = -EINVAL;
+		goto error_no_ccm1;
+	}
+	wusb_dev->ccm1_etd = *ccm1_etd;
+	dev_info(dev, "supported encryption: %s; using %s (0x%02x/%02x)\n",
+		 buf, wusb_et_name(ccm1_etd->bEncryptionType),
+		 ccm1_etd->bEncryptionValue, ccm1_etd->bAuthKeyIndex);
+	result = 0;
+	kfree(secd_buf);
+out:
+	d_fnend(3, dev, "(usb_dev %p, wusb_dev %p) = %d\n",
+		usb_dev, wusb_dev, result);
+	return result;
+
+
+error_no_ccm1:
+error_secd_all:
+	kfree(secd_buf);
+error_secd_alloc:
+error_secd:
+	goto out;
+}
+
+void wusb_dev_sec_rm(struct wusb_dev *wusb_dev)
+{
+	/* Nothing so far */
+}
+
+static void hs_printk(unsigned level, struct device *dev,
+		      struct usb_handshake *hs)
+{
+	d_printf(level, dev,
+		 "  bMessageNumber: %u\n"
+		 "  bStatus:        %u\n"
+		 "  tTKID:          %02x %02x %02x\n"
+		 "  CDID:           %02x %02x %02x %02x %02x %02x %02x %02x\n"
+		 "                  %02x %02x %02x %02x %02x %02x %02x %02x\n"
+		 "  nonce:          %02x %02x %02x %02x %02x %02x %02x %02x\n"
+		 "                  %02x %02x %02x %02x %02x %02x %02x %02x\n"
+		 "  MIC:            %02x %02x %02x %02x %02x %02x %02x %02x\n",
+		 hs->bMessageNumber, hs->bStatus,
+		 hs->tTKID[2], hs->tTKID[1], hs->tTKID[0],
+		 hs->CDID[0], hs->CDID[1], hs->CDID[2], hs->CDID[3],
+		 hs->CDID[4], hs->CDID[5], hs->CDID[6], hs->CDID[7],
+		 hs->CDID[8], hs->CDID[9], hs->CDID[10], hs->CDID[11],
+		 hs->CDID[12], hs->CDID[13], hs->CDID[14], hs->CDID[15],
+		 hs->nonce[0], hs->nonce[1], hs->nonce[2], hs->nonce[3],
+		 hs->nonce[4], hs->nonce[5], hs->nonce[6], hs->nonce[7],
+		 hs->nonce[8], hs->nonce[9], hs->nonce[10], hs->nonce[11],
+		 hs->nonce[12], hs->nonce[13], hs->nonce[14], hs->nonce[15],
+		 hs->MIC[0], hs->MIC[1], hs->MIC[2], hs->MIC[3],
+		 hs->MIC[4], hs->MIC[5], hs->MIC[6], hs->MIC[7]);
+}
+
+/**
+ * Update the address of an unauthenticated WUSB device
+ *
+ * Once we have successfully authenticated, we take it to addr0 state
+ * and then to a normal address.
+ *
+ * Before the device's address (as known by it) was usb_dev->devnum |
+ * 0x80 (unauthenticated address). With this we update it to usb_dev->devnum.
+ */
+static int wusb_dev_update_address(struct wusbhc *wusbhc,
+				   struct wusb_dev *wusb_dev)
+{
+	int result = -ENOMEM;
+	struct usb_device *usb_dev = wusb_dev->usb_dev;
+	struct device *dev = &usb_dev->dev;
+	u8 new_address = wusb_dev->addr & 0x7F;
+
+	/* Set address 0 */
+	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
+				 USB_REQ_SET_ADDRESS, 0,
+				 0, 0, NULL, 0, 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "auth failed: can't set address 0: %d\n",
+			result);
+		goto error_addr0;
+	}
+	result = wusb_set_dev_addr(wusbhc, wusb_dev, 0);
+	if (result < 0)
+		goto error_addr0;
+	usb_ep0_reinit(usb_dev);
+
+	/* Set new (authenticated) address. */
+	result = usb_control_msg(usb_dev, usb_sndctrlpipe(usb_dev, 0),
+				 USB_REQ_SET_ADDRESS, 0,
+				 new_address, 0, NULL, 0,
+				 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "auth failed: can't set address %u: %d\n",
+			new_address, result);
+		goto error_addr;
+	}
+	result = wusb_set_dev_addr(wusbhc, wusb_dev, new_address);
+	if (result < 0)
+		goto error_addr;
+	usb_ep0_reinit(usb_dev);
+	usb_dev->authenticated = 1;
+error_addr:
+error_addr0:
+	return result;
+}
+
+/*
+ *
+ *
+ */
+/* FIXME: split and cleanup */
+int wusb_dev_4way_handshake(struct wusbhc *wusbhc, struct wusb_dev *wusb_dev,
+			    struct wusb_ckhdid *ck)
+{
+	int result = -ENOMEM;
+	struct usb_device *usb_dev = wusb_dev->usb_dev;
+	struct device *dev = &usb_dev->dev;
+	u32 tkid;
+	__le32 tkid_le;
+	struct usb_handshake *hs;
+	struct aes_ccm_nonce ccm_n;
+	u8 mic[8];
+	struct wusb_keydvt_in keydvt_in;
+	struct wusb_keydvt_out keydvt_out;
+
+	hs = kzalloc(3*sizeof(hs[0]), GFP_KERNEL);
+	if (hs == NULL) {
+		dev_err(dev, "can't allocate handshake data\n");
+		goto error_kzalloc;
+	}
+
+	/* We need to turn encryption before beginning the 4way
+	 * hshake (WUSB1.0[.3.2.2]) */
+	result = wusb_dev_set_encryption(usb_dev, 1);
+	if (result < 0)
+		goto error_dev_set_encryption;
+
+	tkid = wusbhc_next_tkid(wusbhc, wusb_dev);
+	tkid_le = cpu_to_le32(tkid);
+
+	hs[0].bMessageNumber = 1;
+	hs[0].bStatus = 0;
+	memcpy(hs[0].tTKID, &tkid_le, sizeof(hs[0].tTKID));
+	hs[0].bReserved = 0;
+	memcpy(hs[0].CDID, &wusb_dev->cdid, sizeof(hs[0].CDID));
+	get_random_bytes(&hs[0].nonce, sizeof(hs[0].nonce));
+	memset(hs[0].MIC, 0, sizeof(hs[0].MIC));	/* Per WUSB1.0[T7-22] */
+
+	d_printf(1, dev, "I: sending hs1:\n");
+	hs_printk(2, dev, &hs[0]);
+
+	result = usb_control_msg(
+		usb_dev, usb_sndctrlpipe(usb_dev, 0),
+		USB_REQ_SET_HANDSHAKE,
+		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+		1, 0, &hs[0], sizeof(hs[0]), 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "Handshake1: request failed: %d\n", result);
+		goto error_hs1;
+	}
+
+	/* Handshake 2, from the device -- need to verify fields */
+	result = usb_control_msg(
+		usb_dev, usb_rcvctrlpipe(usb_dev, 0),
+		USB_REQ_GET_HANDSHAKE,
+		USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+		2, 0, &hs[1], sizeof(hs[1]), 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "Handshake2: request failed: %d\n", result);
+		goto error_hs2;
+	}
+	d_printf(1, dev, "got HS2:\n");
+	hs_printk(2, dev, &hs[1]);
+
+	result = -EINVAL;
+	if (hs[1].bMessageNumber != 2) {
+		dev_err(dev, "Handshake2 failed: bad message number %u\n",
+			hs[1].bMessageNumber);
+		goto error_hs2;
+	}
+	if (hs[1].bStatus != 0) {
+		dev_err(dev, "Handshake2 failed: bad status %u\n",
+			hs[1].bStatus);
+		goto error_hs2;
+	}
+	if (memcmp(hs[0].tTKID, hs[1].tTKID, sizeof(hs[0].tTKID))) {
+		dev_err(dev, "Handshake2 failed: TKID mismatch "
+			"(#1 0x%02x%02x%02x vs #2 0x%02x%02x%02x)\n",
+			hs[0].tTKID[0], hs[0].tTKID[1], hs[0].tTKID[2],
+			hs[1].tTKID[0], hs[1].tTKID[1], hs[1].tTKID[2]);
+		goto error_hs2;
+	}
+	if (memcmp(hs[0].CDID, hs[1].CDID, sizeof(hs[0].CDID))) {
+		dev_err(dev, "Handshake2 failed: CDID mismatch\n");
+		goto error_hs2;
+	}
+
+	/* Setup the CCM nonce */
+	memset(&ccm_n.sfn, 0, sizeof(ccm_n.sfn));	/* Per WUSB1.0[6.5.2] */
+	memcpy(ccm_n.tkid, &tkid_le, sizeof(ccm_n.tkid));
+	ccm_n.src_addr = wusbhc->uwb_rc->uwb_dev.dev_addr;
+	ccm_n.dest_addr.data[0] = wusb_dev->addr;
+	ccm_n.dest_addr.data[1] = 0;
+
+	/* Derive the KCK and PTK from CK, the CCM, H and D nonces */
+	memcpy(keydvt_in.hnonce, hs[0].nonce, sizeof(keydvt_in.hnonce));
+	memcpy(keydvt_in.dnonce, hs[1].nonce, sizeof(keydvt_in.dnonce));
+	result = wusb_key_derive(&keydvt_out, ck->data, &ccm_n, &keydvt_in);
+	if (result < 0) {
+		dev_err(dev, "Handshake2 failed: cannot derive keys: %d\n",
+			result);
+		goto error_hs2;
+	}
+	d_printf(2, dev, "KCK:\n");
+	d_dump(2, dev, keydvt_out.kck, sizeof(keydvt_out.kck));
+	d_printf(2, dev, "PTK:\n");
+	d_dump(2, dev, keydvt_out.ptk, sizeof(keydvt_out.ptk));
+
+	/* Compute MIC and verify it */
+	result = wusb_oob_mic(mic, keydvt_out.kck, &ccm_n, &hs[1]);
+	if (result < 0) {
+		dev_err(dev, "Handshake2 failed: cannot compute MIC: %d\n",
+			result);
+		goto error_hs2;
+	}
+
+	d_printf(2, dev, "MIC:\n");
+	d_dump(2, dev, mic, sizeof(mic));
+	if (memcmp(hs[1].MIC, mic, sizeof(hs[1].MIC))) {
+		dev_err(dev, "Handshake2 failed: MIC mismatch\n");
+		goto error_hs2;
+	}
+
+	/* Send Handshake3 */
+	hs[2].bMessageNumber = 3;
+	hs[2].bStatus = 0;
+	memcpy(hs[2].tTKID, &tkid_le, sizeof(hs[2].tTKID));
+	hs[2].bReserved = 0;
+	memcpy(hs[2].CDID, &wusb_dev->cdid, sizeof(hs[2].CDID));
+	memcpy(hs[2].nonce, hs[0].nonce, sizeof(hs[2].nonce));
+	result = wusb_oob_mic(hs[2].MIC, keydvt_out.kck, &ccm_n, &hs[2]);
+	if (result < 0) {
+		dev_err(dev, "Handshake3 failed: cannot compute MIC: %d\n",
+			result);
+		goto error_hs2;
+	}
+
+	d_printf(1, dev, "I: sending hs3:\n");
+	hs_printk(2, dev, &hs[2]);
+
+	result = usb_control_msg(
+		usb_dev, usb_sndctrlpipe(usb_dev, 0),
+		USB_REQ_SET_HANDSHAKE,
+		USB_DIR_OUT | USB_TYPE_STANDARD | USB_RECIP_DEVICE,
+		3, 0, &hs[2], sizeof(hs[2]), 1000 /* FIXME: arbitrary */);
+	if (result < 0) {
+		dev_err(dev, "Handshake3: request failed: %d\n", result);
+		goto error_hs3;
+	}
+
+	d_printf(1, dev, "I: turning on encryption on host for device\n");
+	d_dump(2, dev, keydvt_out.ptk, sizeof(keydvt_out.ptk));
+	result = wusbhc->set_ptk(wusbhc, wusb_dev->port_idx, tkid,
+				 keydvt_out.ptk, sizeof(keydvt_out.ptk));
+	if (result < 0)
+		goto error_wusbhc_set_ptk;
+
+	d_printf(1, dev, "I: setting a GTK\n");
+	result = wusb_dev_set_gtk(wusbhc, wusb_dev);
+	if (result < 0) {
+		dev_err(dev, "Set GTK for device: request failed: %d\n",
+			result);
+		goto error_wusbhc_set_gtk;
+	}
+
+	/* Update the device's address from unauth to auth */
+	if (usb_dev->authenticated == 0) {
+		d_printf(1, dev, "I: updating addres to auth from non-auth\n");
+		result = wusb_dev_update_address(wusbhc, wusb_dev);
+		if (result < 0)
+			goto error_dev_update_address;
+	}
+	result = 0;
+	d_printf(1, dev, "I: 4way handshke done, device authenticated\n");
+
+error_dev_update_address:
+error_wusbhc_set_gtk:
+error_wusbhc_set_ptk:
+error_hs3:
+error_hs2:
+error_hs1:
+	memset(hs, 0, 3*sizeof(hs[0]));
+	memset(&keydvt_out, 0, sizeof(keydvt_out));
+	memset(&keydvt_in, 0, sizeof(keydvt_in));
+	memset(&ccm_n, 0, sizeof(ccm_n));
+	memset(mic, 0, sizeof(mic));
+	if (result < 0) {
+		/* error path */
+		wusb_dev_set_encryption(usb_dev, 0);
+	}
+error_dev_set_encryption:
+	kfree(hs);
+error_kzalloc:
+	return result;
+}
+
+/*
+ * Once all connected and authenticated devices have received the new
+ * GTK, switch the host to using it.
+ */
+static void wusbhc_gtk_rekey_done_work(struct work_struct *work)
+{
+	struct wusbhc *wusbhc = container_of(work, struct wusbhc, gtk_rekey_done_work);
+	size_t key_size = sizeof(wusbhc->gtk.data);
+
+	mutex_lock(&wusbhc->mutex);
+
+	if (--wusbhc->pending_set_gtks == 0)
+		wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid, &wusbhc->gtk.descr.bKeyData, key_size);
+
+	mutex_unlock(&wusbhc->mutex);
+}
+
+static void wusbhc_set_gtk_callback(struct urb *urb)
+{
+	struct wusbhc *wusbhc = urb->context;
+
+	queue_work(wusbd, &wusbhc->gtk_rekey_done_work);
+}
+
+/**
+ * wusbhc_gtk_rekey - generate and distribute a new GTK
+ * @wusbhc: the WUSB host controller
+ *
+ * Generate a new GTK and distribute it to all connected and
+ * authenticated devices.  When all devices have the new GTK, the host
+ * starts using it.
+ *
+ * This must be called after every device disconnect (see [WUSB]
+ * section 6.2.11.2).
+ */
+void wusbhc_gtk_rekey(struct wusbhc *wusbhc)
+{
+	static const size_t key_size = sizeof(wusbhc->gtk.data);
+	int p;
+
+	wusbhc_generate_gtk(wusbhc);
+
+	for (p = 0; p < wusbhc->ports_max; p++) {
+		struct wusb_dev *wusb_dev;
+
+		wusb_dev = wusbhc->port[p].wusb_dev;
+		if (!wusb_dev || !wusb_dev->usb_dev | !wusb_dev->usb_dev->authenticated)
+			continue;
+
+		usb_fill_control_urb(wusb_dev->set_gtk_urb, wusb_dev->usb_dev,
+				     usb_sndctrlpipe(wusb_dev->usb_dev, 0),
+				     (void *)wusb_dev->set_gtk_req,
+				     &wusbhc->gtk.descr, wusbhc->gtk.descr.bLength,
+				     wusbhc_set_gtk_callback, wusbhc);
+		if (usb_submit_urb(wusb_dev->set_gtk_urb, GFP_KERNEL) == 0)
+			wusbhc->pending_set_gtks++;
+	}
+	if (wusbhc->pending_set_gtks == 0)
+		wusbhc->set_gtk(wusbhc, wusbhc->gtk_tkid, &wusbhc->gtk.descr.bKeyData, key_size);
+}