security/keys/dh.c - linux - Git at Google

 /* Crypto operations using stored keys
  *
  * Copyright (c) 2016, Intel Corporation
  *
  * 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 (at your option) any later version.
  */

 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/scatterlist.h>
 #include <linux/crypto.h>
 #include <crypto/hash.h>
 #include <crypto/kpp.h>
 #include <crypto/dh.h>
 #include <keys/user-type.h>
 #include "internal.h"

 static ssize_t dh_data_from_key(key_serial_t keyid, void **data)
 {
 	struct key *key;
 	key_ref_t key_ref;
 	long status;
 	ssize_t ret;

 	key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
 	if (IS_ERR(key_ref)) {
 		ret = -ENOKEY;
 		goto error;
 	}

 	key = key_ref_to_ptr(key_ref);

 	ret = -EOPNOTSUPP;
 	if (key->type == &key_type_user) {
 		down_read(&key->sem);
 		status = key_validate(key);
 		if (status == 0) {
 			const struct user_key_payload *payload;
 			uint8_t *duplicate;

 			payload = user_key_payload_locked(key);

 			duplicate = kmemdup(payload->data, payload->datalen,
 					    GFP_KERNEL);
 			if (duplicate) {
 				*data = duplicate;
 				ret = payload->datalen;
 			} else {
 				ret = -ENOMEM;
 			}
 		}
 		up_read(&key->sem);
 	}

 	key_put(key);
 error:
 	return ret;
 }

 static void dh_free_data(struct dh *dh)
 {
 	kzfree(dh->key);
 	kzfree(dh->p);
 	kzfree(dh->g);
 }

 struct dh_completion {
 	struct completion completion;
 	int err;
 };

 static void dh_crypto_done(struct crypto_async_request *req, int err)
 {
 	struct dh_completion *compl = req->data;

 	if (err == -EINPROGRESS)
 		return;

 	compl->err = err;
 	complete(&compl->completion);
 }

 struct kdf_sdesc {
 	struct shash_desc shash;
 	char ctx[];
 };

 static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *hashname)
 {
 	struct crypto_shash *tfm;
 	struct kdf_sdesc *sdesc;
 	int size;
 	int err;

 	/* allocate synchronous hash */
 	tfm = crypto_alloc_shash(hashname, 0, 0);
 	if (IS_ERR(tfm)) {
 		pr_info("could not allocate digest TFM handle %s\n", hashname);
 		return PTR_ERR(tfm);
 	}

 	err = -EINVAL;
 	if (crypto_shash_digestsize(tfm) == 0)
 		goto out_free_tfm;

 	err = -ENOMEM;
 	size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
 	sdesc = kmalloc(size, GFP_KERNEL);
 	if (!sdesc)
 		goto out_free_tfm;
 	sdesc->shash.tfm = tfm;
 	sdesc->shash.flags = 0x0;

 	*sdesc_ret = sdesc;

 	return 0;

 out_free_tfm:
 	crypto_free_shash(tfm);
 	return err;
 }

 static void kdf_dealloc(struct kdf_sdesc *sdesc)
 {
 	if (!sdesc)
 		return;

 	if (sdesc->shash.tfm)
 		crypto_free_shash(sdesc->shash.tfm);

 	kzfree(sdesc);
 }

 /*
  * Implementation of the KDF in counter mode according to SP800-108 section 5.1
  * as well as SP800-56A section 5.8.1 (Single-step KDF).
  *
  * SP800-56A:
  * The src pointer is defined as Z || other info where Z is the shared secret
  * from DH and other info is an arbitrary string (see SP800-56A section
  * 5.8.1.2).
  */
 static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
 		   u8 *dst, unsigned int dlen, unsigned int zlen)
 {
 	struct shash_desc *desc = &sdesc->shash;
 	unsigned int h = crypto_shash_digestsize(desc->tfm);
 	int err = 0;
 	u8 *dst_orig = dst;
 	__be32 counter = cpu_to_be32(1);

 	while (dlen) {
 		err = crypto_shash_init(desc);
 		if (err)
 			goto err;

 		err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
 		if (err)
 			goto err;

 		if (zlen && h) {
 			u8 tmpbuffer[32];
 			size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
 			memset(tmpbuffer, 0, chunk);

 			do {
 				err = crypto_shash_update(desc, tmpbuffer,
 							  chunk);
 				if (err)
 					goto err;

 				zlen -= chunk;
 				chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
 			} while (zlen);
 		}

 		if (src && slen) {
 			err = crypto_shash_update(desc, src, slen);
 			if (err)
 				goto err;
 		}

 		err = crypto_shash_final(desc, dst);
 		if (err)
 			goto err;

 		dlen -= h;
 		dst += h;
 		counter = cpu_to_be32(be32_to_cpu(counter) + 1);
 	}

 	return 0;

 err:
 	memzero_explicit(dst_orig, dlen);
 	return err;
 }

 static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
 				 char __user *buffer, size_t buflen,
 				 uint8_t *kbuf, size_t kbuflen, size_t lzero)
 {
 	uint8_t *outbuf = NULL;
 	int ret;
 	size_t outbuf_len = round_up(buflen,
 			             crypto_shash_digestsize(sdesc->shash.tfm));

 	outbuf = kmalloc(outbuf_len, GFP_KERNEL);
 	if (!outbuf) {
 		ret = -ENOMEM;
 		goto err;
 	}

 	ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero);
 	if (ret)
 		goto err;

 	ret = buflen;
 	if (copy_to_user(buffer, outbuf, buflen) != 0)
 		ret = -EFAULT;

 err:
 	kzfree(outbuf);
 	return ret;
 }

 long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
 			 char __user *buffer, size_t buflen,
 			 struct keyctl_kdf_params *kdfcopy)
 {
 	long ret;
 	ssize_t dlen;
 	int secretlen;
 	int outlen;
 	struct keyctl_dh_params pcopy;
 	struct dh dh_inputs;
 	struct scatterlist outsg;
 	struct dh_completion compl;
 	struct crypto_kpp *tfm;
 	struct kpp_request *req;
 	uint8_t *secret;
 	uint8_t *outbuf;
 	struct kdf_sdesc *sdesc = NULL;

 	if (!params || (!buffer && buflen)) {
 		ret = -EINVAL;
 		goto out1;
 	}
 	if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
 		ret = -EFAULT;
 		goto out1;
 	}

 	if (kdfcopy) {
 		char *hashname;

 		if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
 			ret = -EINVAL;
 			goto out1;
 		}

 		if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
 		    kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
 			ret = -EMSGSIZE;
 			goto out1;
 		}

 		/* get KDF name string */
 		hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
 		if (IS_ERR(hashname)) {
 			ret = PTR_ERR(hashname);
 			goto out1;
 		}

 		/* allocate KDF from the kernel crypto API */
 		ret = kdf_alloc(&sdesc, hashname);
 		kfree(hashname);
 		if (ret)
 			goto out1;
 	}

 	memset(&dh_inputs, 0, sizeof(dh_inputs));

 	dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
 	if (dlen < 0) {
 		ret = dlen;
 		goto out1;
 	}
 	dh_inputs.p_size = dlen;

 	dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
 	if (dlen < 0) {
 		ret = dlen;
 		goto out2;
 	}
 	dh_inputs.g_size = dlen;

 	dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
 	if (dlen < 0) {
 		ret = dlen;
 		goto out2;
 	}
 	dh_inputs.key_size = dlen;

 	secretlen = crypto_dh_key_len(&dh_inputs);
 	secret = kmalloc(secretlen, GFP_KERNEL);
 	if (!secret) {
 		ret = -ENOMEM;
 		goto out2;
 	}
 	ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
 	if (ret)
 		goto out3;

 	tfm = crypto_alloc_kpp("dh", CRYPTO_ALG_TYPE_KPP, 0);
 	if (IS_ERR(tfm)) {
 		ret = PTR_ERR(tfm);
 		goto out3;
 	}

 	ret = crypto_kpp_set_secret(tfm, secret, secretlen);
 	if (ret)
 		goto out4;

 	outlen = crypto_kpp_maxsize(tfm);

 	if (!kdfcopy) {
 		/*
 		 * When not using a KDF, buflen 0 is used to read the
 		 * required buffer length
 		 */
 		if (buflen == 0) {
 			ret = outlen;
 			goto out4;
 		} else if (outlen > buflen) {
 			ret = -EOVERFLOW;
 			goto out4;
 		}
 	}

 	outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
 			 GFP_KERNEL);
 	if (!outbuf) {
 		ret = -ENOMEM;
 		goto out4;
 	}

 	sg_init_one(&outsg, outbuf, outlen);

 	req = kpp_request_alloc(tfm, GFP_KERNEL);
 	if (!req) {
 		ret = -ENOMEM;
 		goto out5;
 	}

 	kpp_request_set_input(req, NULL, 0);
 	kpp_request_set_output(req, &outsg, outlen);
 	init_completion(&compl.completion);
 	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 				 CRYPTO_TFM_REQ_MAY_SLEEP,
 				 dh_crypto_done, &compl);

 	/*
 	 * For DH, generate_public_key and generate_shared_secret are
 	 * the same calculation
 	 */
 	ret = crypto_kpp_generate_public_key(req);
 	if (ret == -EINPROGRESS) {
 		wait_for_completion(&compl.completion);
 		ret = compl.err;
 		if (ret)
 			goto out6;
 	}

 	if (kdfcopy) {
 		/*
 		 * Concatenate SP800-56A otherinfo past DH shared secret -- the
 		 * input to the KDF is (DH shared secret || otherinfo)
 		 */
 		if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
 				   kdfcopy->otherinfolen) != 0) {
 			ret = -EFAULT;
 			goto out6;
 		}

 		ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf,
 					    req->dst_len + kdfcopy->otherinfolen,
 					    outlen - req->dst_len);
 	} else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
 		ret = req->dst_len;
 	} else {
 		ret = -EFAULT;
 	}

 out6:
 	kpp_request_free(req);
 out5:
 	kzfree(outbuf);
 out4:
 	crypto_free_kpp(tfm);
 out3:
 	kzfree(secret);
 out2:
 	dh_free_data(&dh_inputs);
 out1:
 	kdf_dealloc(sdesc);
 	return ret;
 }

 long keyctl_dh_compute(struct keyctl_dh_params __user *params,
 		       char __user *buffer, size_t buflen,
 		       struct keyctl_kdf_params __user *kdf)
 {
 	struct keyctl_kdf_params kdfcopy;

 	if (!kdf)
 		return __keyctl_dh_compute(params, buffer, buflen, NULL);

 	if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
 		return -EFAULT;

 	return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
 }
	/* Crypto operations using stored keys
	*
	* Copyright (c) 2016, Intel Corporation
	*
	* 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 (at your option) any later version.
	*/

	#include <linux/slab.h>
	#include <linux/uaccess.h>
	#include <linux/scatterlist.h>
	#include <linux/crypto.h>
	#include <crypto/hash.h>
	#include <crypto/kpp.h>
	#include <crypto/dh.h>
	#include <keys/user-type.h>
	#include "internal.h"

	static ssize_t dh_data_from_key(key_serial_t keyid, void **data)
	{
	struct key *key;
	key_ref_t key_ref;
	long status;
	ssize_t ret;

	key_ref = lookup_user_key(keyid, 0, KEY_NEED_READ);
	if (IS_ERR(key_ref)) {
	ret = -ENOKEY;
	goto error;
	}

	key = key_ref_to_ptr(key_ref);

	ret = -EOPNOTSUPP;
	if (key->type == &key_type_user) {
	down_read(&key->sem);
	status = key_validate(key);
	if (status == 0) {
	const struct user_key_payload *payload;
	uint8_t *duplicate;

	payload = user_key_payload_locked(key);

	duplicate = kmemdup(payload->data, payload->datalen,
	GFP_KERNEL);
	if (duplicate) {
	*data = duplicate;
	ret = payload->datalen;
	} else {
	ret = -ENOMEM;
	}
	}
	up_read(&key->sem);
	}

	key_put(key);
	error:
	return ret;
	}

	static void dh_free_data(struct dh *dh)
	{
	kzfree(dh->key);
	kzfree(dh->p);
	kzfree(dh->g);
	}

	struct dh_completion {
	struct completion completion;
	int err;
	};

	static void dh_crypto_done(struct crypto_async_request *req, int err)
	{
	struct dh_completion *compl = req->data;

	if (err == -EINPROGRESS)
	return;

	compl->err = err;
	complete(&compl->completion);
	}

	struct kdf_sdesc {
	struct shash_desc shash;
	char ctx[];
	};

	static int kdf_alloc(struct kdf_sdesc *sdesc_ret, char hashname)
	{
	struct crypto_shash *tfm;
	struct kdf_sdesc *sdesc;
	int size;
	int err;

	/* allocate synchronous hash */
	tfm = crypto_alloc_shash(hashname, 0, 0);
	if (IS_ERR(tfm)) {
	pr_info("could not allocate digest TFM handle %s\n", hashname);
	return PTR_ERR(tfm);
	}

	err = -EINVAL;
	if (crypto_shash_digestsize(tfm) == 0)
	goto out_free_tfm;

	err = -ENOMEM;
	size = sizeof(struct shash_desc) + crypto_shash_descsize(tfm);
	sdesc = kmalloc(size, GFP_KERNEL);
	if (!sdesc)
	goto out_free_tfm;
	sdesc->shash.tfm = tfm;
	sdesc->shash.flags = 0x0;

	*sdesc_ret = sdesc;

	return 0;

	out_free_tfm:
	crypto_free_shash(tfm);
	return err;
	}

	static void kdf_dealloc(struct kdf_sdesc *sdesc)
	{
	if (!sdesc)
	return;

	if (sdesc->shash.tfm)
	crypto_free_shash(sdesc->shash.tfm);

	kzfree(sdesc);
	}

	/*
	* Implementation of the KDF in counter mode according to SP800-108 section 5.1
	* as well as SP800-56A section 5.8.1 (Single-step KDF).
	*
	* SP800-56A:
	* The src pointer is defined as Z \|\| other info where Z is the shared secret
	* from DH and other info is an arbitrary string (see SP800-56A section
	* 5.8.1.2).
	*/
	static int kdf_ctr(struct kdf_sdesc sdesc, const u8 src, unsigned int slen,
	u8 *dst, unsigned int dlen, unsigned int zlen)
	{
	struct shash_desc *desc = &sdesc->shash;
	unsigned int h = crypto_shash_digestsize(desc->tfm);
	int err = 0;
	u8 *dst_orig = dst;
	__be32 counter = cpu_to_be32(1);

	while (dlen) {
	err = crypto_shash_init(desc);
	if (err)
	goto err;

	err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
	if (err)
	goto err;

	if (zlen && h) {
	u8 tmpbuffer[32];
	size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
	memset(tmpbuffer, 0, chunk);

	do {
	err = crypto_shash_update(desc, tmpbuffer,
	chunk);
	if (err)
	goto err;

	zlen -= chunk;
	chunk = min_t(size_t, zlen, sizeof(tmpbuffer));
	} while (zlen);
	}

	if (src && slen) {
	err = crypto_shash_update(desc, src, slen);
	if (err)
	goto err;
	}

	err = crypto_shash_final(desc, dst);
	if (err)
	goto err;

	dlen -= h;
	dst += h;
	counter = cpu_to_be32(be32_to_cpu(counter) + 1);
	}

	return 0;

	err:
	memzero_explicit(dst_orig, dlen);
	return err;
	}

	static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
	char __user *buffer, size_t buflen,
	uint8_t *kbuf, size_t kbuflen, size_t lzero)
	{
	uint8_t *outbuf = NULL;
	int ret;
	size_t outbuf_len = round_up(buflen,
	crypto_shash_digestsize(sdesc->shash.tfm));

	outbuf = kmalloc(outbuf_len, GFP_KERNEL);
	if (!outbuf) {
	ret = -ENOMEM;
	goto err;
	}

	ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, outbuf_len, lzero);
	if (ret)
	goto err;

	ret = buflen;
	if (copy_to_user(buffer, outbuf, buflen) != 0)
	ret = -EFAULT;

	err:
	kzfree(outbuf);
	return ret;
	}

	long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
	char __user *buffer, size_t buflen,
	struct keyctl_kdf_params *kdfcopy)
	{
	long ret;
	ssize_t dlen;
	int secretlen;
	int outlen;
	struct keyctl_dh_params pcopy;
	struct dh dh_inputs;
	struct scatterlist outsg;
	struct dh_completion compl;
	struct crypto_kpp *tfm;
	struct kpp_request *req;
	uint8_t *secret;
	uint8_t *outbuf;
	struct kdf_sdesc *sdesc = NULL;

	if (!params \|\| (!buffer && buflen)) {
	ret = -EINVAL;
	goto out1;
	}
	if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
	ret = -EFAULT;
	goto out1;
	}

	if (kdfcopy) {
	char *hashname;

	if (memchr_inv(kdfcopy->__spare, 0, sizeof(kdfcopy->__spare))) {
	ret = -EINVAL;
	goto out1;
	}

	if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN \|\|
	kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
	ret = -EMSGSIZE;
	goto out1;
	}

	/* get KDF name string */
	hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
	if (IS_ERR(hashname)) {
	ret = PTR_ERR(hashname);
	goto out1;
	}

	/* allocate KDF from the kernel crypto API */
	ret = kdf_alloc(&sdesc, hashname);
	kfree(hashname);
	if (ret)
	goto out1;
	}

	memset(&dh_inputs, 0, sizeof(dh_inputs));

	dlen = dh_data_from_key(pcopy.prime, &dh_inputs.p);
	if (dlen < 0) {
	ret = dlen;
	goto out1;
	}
	dh_inputs.p_size = dlen;

	dlen = dh_data_from_key(pcopy.base, &dh_inputs.g);
	if (dlen < 0) {
	ret = dlen;
	goto out2;
	}
	dh_inputs.g_size = dlen;

	dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
	if (dlen < 0) {
	ret = dlen;
	goto out2;
	}
	dh_inputs.key_size = dlen;

	secretlen = crypto_dh_key_len(&dh_inputs);
	secret = kmalloc(secretlen, GFP_KERNEL);
	if (!secret) {
	ret = -ENOMEM;
	goto out2;
	}
	ret = crypto_dh_encode_key(secret, secretlen, &dh_inputs);
	if (ret)
	goto out3;

	tfm = crypto_alloc_kpp("dh", CRYPTO_ALG_TYPE_KPP, 0);
	if (IS_ERR(tfm)) {
	ret = PTR_ERR(tfm);
	goto out3;
	}

	ret = crypto_kpp_set_secret(tfm, secret, secretlen);
	if (ret)
	goto out4;

	outlen = crypto_kpp_maxsize(tfm);

	if (!kdfcopy) {
	/*
	* When not using a KDF, buflen 0 is used to read the
	* required buffer length
	*/
	if (buflen == 0) {
	ret = outlen;
	goto out4;
	} else if (outlen > buflen) {
	ret = -EOVERFLOW;
	goto out4;
	}
	}

	outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
	GFP_KERNEL);
	if (!outbuf) {
	ret = -ENOMEM;
	goto out4;
	}

	sg_init_one(&outsg, outbuf, outlen);

	req = kpp_request_alloc(tfm, GFP_KERNEL);
	if (!req) {
	ret = -ENOMEM;
	goto out5;
	}

	kpp_request_set_input(req, NULL, 0);
	kpp_request_set_output(req, &outsg, outlen);
	init_completion(&compl.completion);
	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG \|
	CRYPTO_TFM_REQ_MAY_SLEEP,
	dh_crypto_done, &compl);

	/*
	* For DH, generate_public_key and generate_shared_secret are
	* the same calculation
	*/
	ret = crypto_kpp_generate_public_key(req);
	if (ret == -EINPROGRESS) {
	wait_for_completion(&compl.completion);
	ret = compl.err;
	if (ret)
	goto out6;
	}

	if (kdfcopy) {
	/*
	* Concatenate SP800-56A otherinfo past DH shared secret -- the
	* input to the KDF is (DH shared secret \|\| otherinfo)
	*/
	if (copy_from_user(outbuf + req->dst_len, kdfcopy->otherinfo,
	kdfcopy->otherinfolen) != 0) {
	ret = -EFAULT;
	goto out6;
	}

	ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, outbuf,
	req->dst_len + kdfcopy->otherinfolen,
	outlen - req->dst_len);
	} else if (copy_to_user(buffer, outbuf, req->dst_len) == 0) {
	ret = req->dst_len;
	} else {
	ret = -EFAULT;
	}

	out6:
	kpp_request_free(req);
	out5:
	kzfree(outbuf);
	out4:
	crypto_free_kpp(tfm);
	out3:
	kzfree(secret);
	out2:
	dh_free_data(&dh_inputs);
	out1:
	kdf_dealloc(sdesc);
	return ret;
	}

	long keyctl_dh_compute(struct keyctl_dh_params __user *params,
	char __user *buffer, size_t buflen,
	struct keyctl_kdf_params __user *kdf)
	{
	struct keyctl_kdf_params kdfcopy;

	if (!kdf)
	return __keyctl_dh_compute(params, buffer, buflen, NULL);

	if (copy_from_user(&kdfcopy, kdf, sizeof(kdfcopy)) != 0)
	return -EFAULT;

	return __keyctl_dh_compute(params, buffer, buflen, &kdfcopy);
	}