1 files changed, 352 insertions, 0 deletions
diff --git a/lib/crypto_backend/crypto_cipher_kernel.c b/lib/crypto_backend/crypto_cipher_kernel.c
new file mode 100644
index 0000000..607c3d3
--- /dev/null
+++ b/lib/crypto_backend/crypto_cipher_kernel.c
@@ -0,0 +1,352 @@
+/*
+ * Linux kernel userspace API crypto backend implementation (skcipher)
+ *
+ * Copyright (C) 2012-2021 Red Hat, Inc. All rights reserved.
+ * Copyright (C) 2012-2021 Milan Broz
+ *
+ * This file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This file 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this file; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include "crypto_backend_internal.h"
+
+#ifdef ENABLE_AF_ALG
+
+#include <linux/if_alg.h>
+
+#ifndef AF_ALG
+#define AF_ALG 38
+#endif
+#ifndef SOL_ALG
+#define SOL_ALG 279
+#endif
+
+#ifndef ALG_SET_AEAD_AUTHSIZE
+#define ALG_SET_AEAD_AUTHSIZE 5
+#endif
+
+/*
+ * ciphers
+ *
+ * ENOENT - algorithm not available
+ * ENOTSUP - AF_ALG family not available
+ * (but cannot check specifically for skcipher API)
+ */
+static int _crypt_cipher_init(struct crypt_cipher_kernel *ctx,
+			      const void *key, size_t key_length,
+			      size_t tag_length, struct sockaddr_alg *sa)
+{
+	if (!ctx)
+		return -EINVAL;
+
+	ctx->opfd = -1;
+	ctx->tfmfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
+	if (ctx->tfmfd < 0) {
+		crypt_cipher_destroy_kernel(ctx);
+		return -ENOTSUP;
+	}
+
+	if (bind(ctx->tfmfd, (struct sockaddr *)sa, sizeof(*sa)) < 0) {
+		crypt_cipher_destroy_kernel(ctx);
+		return -ENOENT;
+	}
+
+	if (setsockopt(ctx->tfmfd, SOL_ALG, ALG_SET_KEY, key, key_length) < 0) {
+		crypt_cipher_destroy_kernel(ctx);
+		return -EINVAL;
+	}
+
+	if (tag_length && setsockopt(ctx->tfmfd, SOL_ALG, ALG_SET_AEAD_AUTHSIZE, NULL, tag_length) < 0) {
+		crypt_cipher_destroy_kernel(ctx);
+		return -EINVAL;
+	}
+
+	ctx->opfd = accept(ctx->tfmfd, NULL, 0);
+	if (ctx->opfd < 0) {
+		crypt_cipher_destroy_kernel(ctx);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int crypt_cipher_init_kernel(struct crypt_cipher_kernel *ctx, const char *name,
+			     const char *mode, const void *key, size_t key_length)
+{
+	struct sockaddr_alg sa = {
+		.salg_family = AF_ALG,
+		.salg_type = "skcipher",
+	};
+	int r;
+
+	if (!strcmp(name, "cipher_null"))
+		key_length = 0;
+
+	r = snprintf((char *)sa.salg_name, sizeof(sa.salg_name), "%s(%s)", mode, name);
+	if (r < 0 || (size_t)r >= sizeof(sa.salg_name))
+		return -EINVAL;
+
+	return _crypt_cipher_init(ctx, key, key_length, 0, &sa);
+}
+
+/* The in/out should be aligned to page boundary */
+static int _crypt_cipher_crypt(struct crypt_cipher_kernel *ctx,
+			       const char *in, size_t in_length,
+			       char *out, size_t out_length,
+			       const char *iv, size_t iv_length,
+			       uint32_t direction)
+{
+	int r = 0;
+	ssize_t len;
+	struct af_alg_iv *alg_iv;
+	struct cmsghdr *header;
+	uint32_t *type;
+	struct iovec iov = {
+		.iov_base = (void*)(uintptr_t)in,
+		.iov_len = in_length,
+	};
+	int iv_msg_size = iv ? CMSG_SPACE(sizeof(*alg_iv) + iv_length) : 0;
+	char buffer[CMSG_SPACE(sizeof(*type)) + iv_msg_size];
+	struct msghdr msg = {
+		.msg_control = buffer,
+		.msg_controllen = sizeof(buffer),
+		.msg_iov = &iov,
+		.msg_iovlen = 1,
+	};
+
+	if (!in || !out || !in_length)
+		return -EINVAL;
+
+	if ((!iv && iv_length) || (iv && !iv_length))
+		return -EINVAL;
+
+	memset(buffer, 0, sizeof(buffer));
+
+	/* Set encrypt/decrypt operation */
+	header = CMSG_FIRSTHDR(&msg);
+	if (!header)
+		return -EINVAL;
+
+	header->cmsg_level = SOL_ALG;
+	header->cmsg_type = ALG_SET_OP;
+	header->cmsg_len = CMSG_LEN(sizeof(*type));
+	type = (void*)CMSG_DATA(header);
+	*type = direction;
+
+	/* Set IV */
+	if (iv) {
+		header = CMSG_NXTHDR(&msg, header);
+		if (!header)
+			return -EINVAL;
+
+		header->cmsg_level = SOL_ALG;
+		header->cmsg_type = ALG_SET_IV;
+		header->cmsg_len = iv_msg_size;
+		alg_iv = (void*)CMSG_DATA(header);
+		alg_iv->ivlen = iv_length;
+		memcpy(alg_iv->iv, iv, iv_length);
+	}
+
+	len = sendmsg(ctx->opfd, &msg, 0);
+	if (len != (ssize_t)(in_length)) {
+		r = -EIO;
+		goto bad;
+	}
+
+	len = read(ctx->opfd, out, out_length);
+	if (len != (ssize_t)out_length)
+		r = -EIO;
+bad:
+	crypt_backend_memzero(buffer, sizeof(buffer));
+	return r;
+}
+
+int crypt_cipher_encrypt_kernel(struct crypt_cipher_kernel *ctx,
+				const char *in, char *out, size_t length,
+				const char *iv, size_t iv_length)
+{
+	return _crypt_cipher_crypt(ctx, in, length, out, length,
+				   iv, iv_length, ALG_OP_ENCRYPT);
+}
+
+int crypt_cipher_decrypt_kernel(struct crypt_cipher_kernel *ctx,
+				const char *in, char *out, size_t length,
+				const char *iv, size_t iv_length)
+{
+	return _crypt_cipher_crypt(ctx, in, length, out, length,
+				   iv, iv_length, ALG_OP_DECRYPT);
+}
+
+void crypt_cipher_destroy_kernel(struct crypt_cipher_kernel *ctx)
+{
+	if (ctx->tfmfd >= 0)
+		close(ctx->tfmfd);
+	if (ctx->opfd >= 0)
+		close(ctx->opfd);
+
+	ctx->tfmfd = -1;
+	ctx->opfd = -1;
+}
+
+int crypt_cipher_check_kernel(const char *name, const char *mode,
+			      const char *integrity, size_t key_length)
+{
+	struct crypt_cipher_kernel c;
+	char mode_name[64], tmp_salg_name[180], *real_mode = NULL, *cipher_iv = NULL, *key;
+	const char *salg_type;
+	bool aead;
+	int r;
+	struct sockaddr_alg sa = {
+		.salg_family = AF_ALG,
+	};
+
+	aead = integrity && strcmp(integrity, "none");
+
+	/* Remove IV if present */
+	if (mode) {
+		strncpy(mode_name, mode, sizeof(mode_name));
+		mode_name[sizeof(mode_name) - 1] = 0;
+		cipher_iv = strchr(mode_name, '-');
+		if (cipher_iv) {
+			*cipher_iv = '\0';
+			real_mode = mode_name;
+		}
+	}
+
+	salg_type = aead ? "aead" : "skcipher";
+	r = snprintf((char *)sa.salg_type, sizeof(sa.salg_type), "%s", salg_type);
+	if (r < 0 || (size_t)r >= sizeof(sa.salg_name))
+		return -EINVAL;
+
+	memset(tmp_salg_name, 0, sizeof(tmp_salg_name));
+
+	/* FIXME: this is duplicating a part of devmapper backend */
+	if (aead && !strcmp(integrity, "poly1305"))
+		r = snprintf(tmp_salg_name, sizeof(tmp_salg_name), "rfc7539(%s,%s)", name, integrity);
+	else if (!real_mode)
+		r = snprintf(tmp_salg_name, sizeof(tmp_salg_name), "%s", name);
+	else if (aead && !strcmp(real_mode, "ccm"))
+		r = snprintf(tmp_salg_name, sizeof(tmp_salg_name), "rfc4309(%s(%s))", real_mode, name);
+	else
+		r = snprintf(tmp_salg_name, sizeof(tmp_salg_name), "%s(%s)", real_mode, name);
+
+	if (r < 0 || (size_t)r >= sizeof(tmp_salg_name))
+		return -EINVAL;
+
+	memcpy(sa.salg_name, tmp_salg_name, sizeof(sa.salg_name));
+
+	key = malloc(key_length);
+	if (!key)
+		return -ENOMEM;
+
+	/* We cannot use RNG yet, any key works here, tweak the first part if it is split key (XTS). */
+	memset(key, 0xab, key_length);
+	*key = 0xef;
+
+	r = _crypt_cipher_init(&c, key, key_length, 0, &sa);
+	crypt_cipher_destroy_kernel(&c);
+	free(key);
+
+	return r;
+}
+
+int crypt_bitlk_decrypt_key_kernel(const void *key, size_t key_length,
+				   const char *in, char *out, size_t length,
+				   const char *iv, size_t iv_length,
+				   const char *tag, size_t tag_length)
+{
+	struct crypt_cipher_kernel c;
+	struct sockaddr_alg sa = {
+		.salg_family = AF_ALG,
+		.salg_type = "aead",
+		.salg_name = "ccm(aes)",
+	};
+	int r;
+	char buffer[128], ccm_iv[16];
+
+	if (length + tag_length > sizeof(buffer))
+		return -EINVAL;
+
+	if (iv_length > sizeof(ccm_iv) - 2)
+		return -EINVAL;
+
+	r = _crypt_cipher_init(&c, key, key_length, tag_length, &sa);
+	if (r < 0)
+		return r;
+
+	memcpy(buffer, in, length);
+	memcpy(buffer + length, tag, tag_length);
+
+	/* CCM IV - RFC3610 */
+	memset(ccm_iv, 0, sizeof(ccm_iv));
+	ccm_iv[0] = 15 - iv_length - 1;
+	memcpy(ccm_iv + 1, iv, iv_length);
+	memset(ccm_iv + 1 + iv_length, 0, ccm_iv[0] + 1);
+	iv_length = sizeof(ccm_iv);
+
+	r =  _crypt_cipher_crypt(&c, buffer, length + tag_length, out, length,
+				 ccm_iv, iv_length, ALG_OP_DECRYPT);
+
+	crypt_cipher_destroy_kernel(&c);
+	crypt_backend_memzero(buffer, sizeof(buffer));
+
+	return r;
+}
+
+#else /* ENABLE_AF_ALG */
+int crypt_cipher_init_kernel(struct crypt_cipher_kernel *ctx, const char *name,
+			     const char *mode, const void *key, size_t key_length)
+{
+	return -ENOTSUP;
+}
+
+void crypt_cipher_destroy_kernel(struct crypt_cipher_kernel *ctx)
+{
+	return;
+}
+
+int crypt_cipher_encrypt_kernel(struct crypt_cipher_kernel *ctx,
+				const char *in, char *out, size_t length,
+				const char *iv, size_t iv_length)
+{
+	return -EINVAL;
+}
+int crypt_cipher_decrypt_kernel(struct crypt_cipher_kernel *ctx,
+				const char *in, char *out, size_t length,
+				const char *iv, size_t iv_length)
+{
+	return -EINVAL;
+}
+int crypt_cipher_check_kernel(const char *name, const char *mode,
+			      const char *integrity, size_t key_length)
+{
+	/* Cannot check, expect success. */
+	return 0;
+}
+int crypt_bitlk_decrypt_key_kernel(const void *key, size_t key_length,
+				   const char *in, char *out, size_t length,
+				   const char *iv, size_t iv_length,
+				   const char *tag, size_t tag_length)
+{
+	return -ENOTSUP;
+}
+#endif