1 files changed, 184 insertions, 116 deletions

diff --git a/security/keys/dh.c b/security/keys/dh.c
index e603bd912e4c..4755d4b4f945 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -8,34 +8,17 @@
  * 2 of the License, or (at your option) any later version.
  */
 
-#include <linux/mpi.h>
 #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"
 
-/*
- * Public key or shared secret generation function [RFC2631 sec 2.1.1]
- *
- * ya = g^xa mod p;
- * or
- * ZZ = yb^xa mod p;
- *
- * where xa is the local private key, ya is the local public key, g is
- * the generator, p is the prime, yb is the remote public key, and ZZ
- * is the shared secret.
- *
- * Both are the same calculation, so g or yb are the "base" and ya or
- * ZZ are the "result".
- */
-static int do_dh(MPI result, MPI base, MPI xa, MPI p)
-{
-	return mpi_powm(result, base, xa, p);
-}
-
-static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi)
+static ssize_t dh_data_from_key(key_serial_t keyid, void **data)
 {
 	struct key *key;
 	key_ref_t key_ref;
@@ -56,19 +39,17 @@ static ssize_t mpi_from_key(key_serial_t keyid, size_t maxlen, MPI *mpi)
 		status = key_validate(key);
 		if (status == 0) {
 			const struct user_key_payload *payload;
+			uint8_t *duplicate;
 
 			payload = user_key_payload_locked(key);
 
-			if (maxlen == 0) {
-				*mpi = NULL;
+			duplicate = kmemdup(payload->data, payload->datalen,
+					    GFP_KERNEL);
+			if (duplicate) {
+				*data = duplicate;
 				ret = payload->datalen;
-			} else if (payload->datalen <= maxlen) {
-				*mpi = mpi_read_raw_data(payload->data,
-							 payload->datalen);
-				if (*mpi)
-					ret = payload->datalen;
 			} else {
-				ret = -EINVAL;
+				ret = -ENOMEM;
 			}
 		}
 		up_read(&key->sem);
@@ -79,6 +60,29 @@ 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[];
@@ -89,6 +93,7 @@ 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);
@@ -97,16 +102,25 @@ static int kdf_alloc(struct kdf_sdesc **sdesc_ret, char *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)
-		return -ENOMEM;
+		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)
@@ -120,14 +134,6 @@ static void kdf_dealloc(struct kdf_sdesc *sdesc)
 	kzfree(sdesc);
 }
 
-/* convert 32 bit integer into its string representation */
-static inline void crypto_kw_cpu_to_be32(u32 val, u8 *buf)
-{
-	__be32 *a = (__be32 *)buf;
-
-	*a = cpu_to_be32(val);
-}
-
 /*
  * 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).
@@ -138,25 +144,39 @@ static inline void crypto_kw_cpu_to_be32(u32 val, u8 *buf)
  * 5.8.1.2).
  */
 static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
-		   u8 *dst, unsigned int dlen)
+		   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;
-	u32 i = 1;
-	u8 iteration[sizeof(u32)];
+	__be32 counter = cpu_to_be32(1);
 
 	while (dlen) {
 		err = crypto_shash_init(desc);
 		if (err)
 			goto err;
 
-		crypto_kw_cpu_to_be32(i, iteration);
-		err = crypto_shash_update(desc, iteration, sizeof(u32));
+		err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
 		if (err)
 			goto err;
 
+		if (zlen && h) {
+			u8 tmpbuffer[h];
+			size_t chunk = min_t(size_t, zlen, h);
+			memset(tmpbuffer, 0, chunk);
+
+			do {
+				err = crypto_shash_update(desc, tmpbuffer,
+							  chunk);
+				if (err)
+					goto err;
+
+				zlen -= chunk;
+				chunk = min_t(size_t, zlen, h);
+			} while (zlen);
+		}
+
 		if (src && slen) {
 			err = crypto_shash_update(desc, src, slen);
 			if (err)
@@ -179,7 +199,7 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
 
 			dlen -= h;
 			dst += h;
-			i++;
+			counter = cpu_to_be32(be32_to_cpu(counter) + 1);
 		}
 	}
 
@@ -192,7 +212,7 @@ err:
 
 static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
 				 char __user *buffer, size_t buflen,
-				 uint8_t *kbuf, size_t kbuflen)
+				 uint8_t *kbuf, size_t kbuflen, size_t lzero)
 {
 	uint8_t *outbuf = NULL;
 	int ret;
@@ -203,7 +223,7 @@ static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc,
 		goto err;
 	}
 
-	ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, buflen);
+	ret = kdf_ctr(sdesc, kbuf, kbuflen, outbuf, buflen, lzero);
 	if (ret)
 		goto err;
 
@@ -221,21 +241,26 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
 			 struct keyctl_kdf_params *kdfcopy)
 {
 	long ret;
-	MPI base, private, prime, result;
-	unsigned nbytes;
+	ssize_t dlen;
+	int secretlen;
+	int outlen;
 	struct keyctl_dh_params pcopy;
-	uint8_t *kbuf;
-	ssize_t keylen;
-	size_t resultlen;
+	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 out;
+		goto out1;
 	}
 	if (copy_from_user(&pcopy, params, sizeof(pcopy)) != 0) {
 		ret = -EFAULT;
-		goto out;
+		goto out1;
 	}
 
 	if (kdfcopy) {
@@ -244,104 +269,147 @@ long __keyctl_dh_compute(struct keyctl_dh_params __user *params,
 		if (buflen > KEYCTL_KDF_MAX_OUTPUT_LEN ||
 		    kdfcopy->otherinfolen > KEYCTL_KDF_MAX_OI_LEN) {
 			ret = -EMSGSIZE;
-			goto out;
+			goto out1;
 		}
 
 		/* get KDF name string */
 		hashname = strndup_user(kdfcopy->hashname, CRYPTO_MAX_ALG_NAME);
 		if (IS_ERR(hashname)) {
 			ret = PTR_ERR(hashname);
-			goto out;
+			goto out1;
 		}
 
 		/* allocate KDF from the kernel crypto API */
 		ret = kdf_alloc(&sdesc, hashname);
 		kfree(hashname);
 		if (ret)
-			goto out;
+			goto out1;
 	}
 
-	/*
-	 * If the caller requests postprocessing with a KDF, allow an
-	 * arbitrary output buffer size since the KDF ensures proper truncation.
-	 */
-	keylen = mpi_from_key(pcopy.prime, kdfcopy ? SIZE_MAX : buflen, &prime);
-	if (keylen < 0 || !prime) {
-		/* buflen == 0 may be used to query the required buffer size,
-		 * which is the prime key length.
-		 */
-		ret = keylen;
-		goto out;
+	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;
 
-	/* The result is never longer than the prime */
-	resultlen = keylen;
+	dlen = dh_data_from_key(pcopy.private, &dh_inputs.key);
+	if (dlen < 0) {
+		ret = dlen;
+		goto out2;
+	}
+	dh_inputs.key_size = dlen;
 
-	keylen = mpi_from_key(pcopy.base, SIZE_MAX, &base);
-	if (keylen < 0 || !base) {
-		ret = keylen;
-		goto error1;
+	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;
 
-	keylen = mpi_from_key(pcopy.private, SIZE_MAX, &private);
-	if (keylen < 0 || !private) {
-		ret = keylen;
-		goto error2;
+	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;
+		}
 	}
 
-	result = mpi_alloc(0);
-	if (!result) {
+	outbuf = kzalloc(kdfcopy ? (outlen + kdfcopy->otherinfolen) : outlen,
+			 GFP_KERNEL);
+	if (!outbuf) {
 		ret = -ENOMEM;
-		goto error3;
+		goto out4;
 	}
 
-	/* allocate space for DH shared secret and SP800-56A otherinfo */
-	kbuf = kmalloc(kdfcopy ? (resultlen + kdfcopy->otherinfolen) : resultlen,
-		       GFP_KERNEL);
-	if (!kbuf) {
+	sg_init_one(&outsg, outbuf, outlen);
+
+	req = kpp_request_alloc(tfm, GFP_KERNEL);
+	if (!req) {
 		ret = -ENOMEM;
-		goto error4;
+		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);
+
 	/*
-	 * Concatenate SP800-56A otherinfo past DH shared secret -- the
-	 * input to the KDF is (DH shared secret || otherinfo)
+	 * For DH, generate_public_key and generate_shared_secret are
+	 * the same calculation
 	 */
-	if (kdfcopy && kdfcopy->otherinfo &&
-	    copy_from_user(kbuf + resultlen, kdfcopy->otherinfo,
-			   kdfcopy->otherinfolen) != 0) {
-		ret = -EFAULT;
-		goto error5;
+	ret = crypto_kpp_generate_public_key(req);
+	if (ret == -EINPROGRESS) {
+		wait_for_completion(&compl.completion);
+		ret = compl.err;
+		if (ret)
+			goto out6;
 	}
 
-	ret = do_dh(result, base, private, prime);
-	if (ret)
-		goto error5;
-
-	ret = mpi_read_buffer(result, kbuf, resultlen, &nbytes, NULL);
-	if (ret != 0)
-		goto error5;
-
 	if (kdfcopy) {
-		ret = keyctl_dh_compute_kdf(sdesc, buffer, buflen, kbuf,
-					    resultlen + kdfcopy->otherinfolen);
-	} else {
-		ret = nbytes;
-		if (copy_to_user(buffer, kbuf, nbytes) != 0)
+		/*
+		 * 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;
 	}
 
-error5:
-	kzfree(kbuf);
-error4:
-	mpi_free(result);
-error3:
-	mpi_free(private);
-error2:
-	mpi_free(base);
-error1:
-	mpi_free(prime);
-out:
+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;
 }