linux-kernel - [PATCH 4.7 20/69] KEYS: Fix skcipher IV clobbering

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Date:   Wed, 28 Sep 2016 11:05:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH 4.7 20/69] KEYS: Fix skcipher IV clobbering

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@...dor.apana.org.au>

commit 456bee986e0a372ad4beed5d3cedb3622633d9df upstream.

The IV must not be modified by the skcipher operation so we need
to duplicate it.

Fixes: c3917fd9dfbc ("KEYS: Use skcipher")
Reported-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 security/keys/encrypted-keys/encrypted.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/security/keys/encrypted-keys/encrypted.c
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -29,6 +29,7 @@
 #include <linux/rcupdate.h>
 #include <linux/scatterlist.h>
 #include <linux/ctype.h>
+#include <crypto/aes.h>
 #include <crypto/hash.h>
 #include <crypto/sha.h>
 #include <crypto/skcipher.h>
@@ -478,6 +479,7 @@ static int derived_key_encrypt(struct en
 	struct crypto_skcipher *tfm;
 	struct skcipher_request *req;
 	unsigned int encrypted_datalen;
+	u8 iv[AES_BLOCK_SIZE];
 	unsigned int padlen;
 	char pad[16];
 	int ret;
@@ -500,8 +502,8 @@ static int derived_key_encrypt(struct en
 	sg_init_table(sg_out, 1);
 	sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
 
-	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
-				   epayload->iv);
+	memcpy(iv, epayload->iv, sizeof(iv));
+	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
 	ret = crypto_skcipher_encrypt(req);
 	tfm = crypto_skcipher_reqtfm(req);
 	skcipher_request_free(req);
@@ -581,6 +583,7 @@ static int derived_key_decrypt(struct en
 	struct crypto_skcipher *tfm;
 	struct skcipher_request *req;
 	unsigned int encrypted_datalen;
+	u8 iv[AES_BLOCK_SIZE];
 	char pad[16];
 	int ret;
 
@@ -599,8 +602,8 @@ static int derived_key_decrypt(struct en
 		   epayload->decrypted_datalen);
 	sg_set_buf(&sg_out[1], pad, sizeof pad);
 
-	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
-				   epayload->iv);
+	memcpy(iv, epayload->iv, sizeof(iv));
+	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
 	ret = crypto_skcipher_decrypt(req);
 	tfm = crypto_skcipher_reqtfm(req);
 	skcipher_request_free(req);