Commit 4b4c6fdb authored by Eric Biggers's avatar Eric Biggers Committed by Steve French
Browse files

smb: client: Use HMAC-SHA256 library for key generation 



Convert generate_key() to use the HMAC-SHA256 library instead of a
"hmac(sha256)" crypto_shash.  This is simpler and faster.  With the
library there's no need to allocate memory, no need to handle errors,
and the HMAC-SHA256 code is accessed directly without inefficient
indirect calls and other unnecessary API overhead.

Also remove the unnecessary 'hashptr' variable.

For now smb3_crypto_shash_allocate() still allocates a "hmac(sha256)"
crypto_shash.  It will be removed in a later commit.

Reviewed-by: default avatarStefan Metzmacher <metze@samba.org>
Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarEric Biggers <ebiggers@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent af5fea51

fs/smb/client/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ config CIFS 
	select CRYPTO_ECB

	select CRYPTO_AES

	select CRYPTO_LIB_ARC4

	select CRYPTO_LIB_SHA256

	select CRYPTO_LIB_SHA512

	select KEYS

	select DNS_RESOLVER

fs/smb/client/smb2transport.c

+14 −54
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/mempool.h>

#include <linux/highmem.h>

#include <crypto/aead.h>

#include <crypto/sha2.h>

#include "cifsglob.h"

#include "cifsproto.h"

#include "smb2proto.h"
@@ -336,8 +337,8 @@ static int generate_key(struct cifs_ses *ses, struct kvec label, 
	__u8 L256[4] = {0, 0, 1, 0};

	int rc = 0;

	unsigned char prfhash[SMB2_HMACSHA256_SIZE];

	unsigned char *hashptr = prfhash;

	struct TCP_Server_Info *server = ses->server;

	struct hmac_sha256_ctx hmac_ctx;



	memset(prfhash, 0x0, SMB2_HMACSHA256_SIZE);

	memset(key, 0x0, key_size);
@@ -345,67 +346,26 @@ static int generate_key(struct cifs_ses *ses, struct kvec label, 
	rc = smb3_crypto_shash_allocate(server);

	if (rc) {

		cifs_server_dbg(VFS, "%s: crypto alloc failed\n", __func__);

		goto smb3signkey_ret;

	}



	rc = crypto_shash_setkey(server->secmech.hmacsha256->tfm,

		ses->auth_key.response, SMB2_NTLMV2_SESSKEY_SIZE);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not set with session key\n", __func__);

		goto smb3signkey_ret;

	}



	rc = crypto_shash_init(server->secmech.hmacsha256);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not init sign hmac\n", __func__);

		goto smb3signkey_ret;

	}



	rc = crypto_shash_update(server->secmech.hmacsha256, i, 4);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not update with n\n", __func__);

		goto smb3signkey_ret;

	}



	rc = crypto_shash_update(server->secmech.hmacsha256, label.iov_base, label.iov_len);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not update with label\n", __func__);

		goto smb3signkey_ret;

	}



	rc = crypto_shash_update(server->secmech.hmacsha256, &zero, 1);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not update with zero\n", __func__);

		goto smb3signkey_ret;

		return rc;

	}



	rc = crypto_shash_update(server->secmech.hmacsha256, context.iov_base, context.iov_len);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not update with context\n", __func__);

		goto smb3signkey_ret;

	}

	hmac_sha256_init_usingrawkey(&hmac_ctx, ses->auth_key.response,

				     SMB2_NTLMV2_SESSKEY_SIZE);

	hmac_sha256_update(&hmac_ctx, i, 4);

	hmac_sha256_update(&hmac_ctx, label.iov_base, label.iov_len);

	hmac_sha256_update(&hmac_ctx, &zero, 1);

	hmac_sha256_update(&hmac_ctx, context.iov_base, context.iov_len);



	if ((server->cipher_type == SMB2_ENCRYPTION_AES256_CCM) ||

		(server->cipher_type == SMB2_ENCRYPTION_AES256_GCM)) {

		rc = crypto_shash_update(server->secmech.hmacsha256, L256, 4);

		hmac_sha256_update(&hmac_ctx, L256, 4);

	} else {

		rc = crypto_shash_update(server->secmech.hmacsha256, L128, 4);

	}

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not update with L\n", __func__);

		goto smb3signkey_ret;

		hmac_sha256_update(&hmac_ctx, L128, 4);

	}

	hmac_sha256_final(&hmac_ctx, prfhash);



	rc = crypto_shash_final(server->secmech.hmacsha256, hashptr);

	if (rc) {

		cifs_server_dbg(VFS, "%s: Could not generate sha256 hash\n", __func__);

		goto smb3signkey_ret;

	}



	memcpy(key, hashptr, key_size);



smb3signkey_ret:

	return rc;

	memcpy(key, prfhash, key_size);

	return 0;

}



struct derivation {