Implemented signer interface using AF_ALG

2010-12-20 09:52:02 +01:00
parent 6f08911321
commit e75e1c9473
4 changed files with 334 additions and 1 deletions
@@ -0,0 +1,255 @@
+/*
+ * Copyright (C) 2010 Martin Willi
+ * Copyright (C) 2010 revosec AG
+ *
+ * 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.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+#include "af_alg_signer.h"
+
+#include <unistd.h>
+#include <errno.h>
+#include <linux/socket.h>
+#include <linux/if_alg.h>
+
+#include <debug.h>
+
+#ifndef AF_ALG
+#define AF_ALG		38
+#endif /* AF_ALG */
+
+#ifndef SOL_ALG
+#define SOL_ALG 279
+#endif /* SOL_ALG */
+
+typedef struct private_af_alg_signer_t private_af_alg_signer_t;
+
+/**
+ * Private data structure with signing context.
+ */
+struct private_af_alg_signer_t {
+
+	/**
+	 * Public interface of af_alg_signer_t.
+	 */
+	af_alg_signer_t public;
+
+	/**
+	 * Transform fd
+	 */
+	int tfm;
+
+	/**
+	 * Current operation fd, -1 if none
+	 */
+	int op;
+
+	/**
+	 * Size of the truncated signature
+	 */
+	size_t block_size;
+
+	/**
+	 * Default key size
+	 */
+	size_t key_size;
+};
+
+/**
+ * Get the kernel algorithm string and block/key size for our identifier
+ */
+static size_t lookup_alg(integrity_algorithm_t algo, char *name,
+						 size_t *key_size)
+{
+	static struct {
+		integrity_algorithm_t id;
+		char *name;
+		size_t block_size;
+		size_t key_size;
+	} algs[] = {
+		{AUTH_HMAC_MD5_96,			"hmac(md5)",		12,		16,	},
+		{AUTH_HMAC_MD5_128,			"hmac(md5)",		16,		16,	},
+		{AUTH_HMAC_SHA1_96,			"hmac(sha1)",		12,		20,	},
+		{AUTH_HMAC_SHA1_128,		"hmac(sha1)",		16,		20,	},
+		{AUTH_HMAC_SHA1_160,		"hmac(sha1)",		20,		20,	},
+		{AUTH_HMAC_SHA2_256_96,		"hmac(sha256)",		12,		32,	},
+		{AUTH_HMAC_SHA2_256_128,	"hmac(sha256)",		16,		32,	},
+		{AUTH_HMAC_SHA2_256_256,	"hmac(sha384)",		32,		32,	},
+		{AUTH_HMAC_SHA2_384_192,	"hmac(sha384)",		24,		48,	},
+		{AUTH_HMAC_SHA2_384_384,	"hmac(sha384)",		48,		48,	},
+		{AUTH_HMAC_SHA2_512_256,	"hmac(sha512)",		32,		64,	},
+		{AUTH_AES_XCBC_96,			"xcbc(aes)",		12,		16,	},
+		{AUTH_CAMELLIA_XCBC_96,		"xcbc(camellia)",	12,		16,	},
+	};
+	int i;
+
+	for (i = 0; i < countof(algs); i++)
+	{
+		if (algs[i].id == algo)
+		{
+			strcpy(name, algs[i].name);
+			*key_size = algs[i].key_size;
+			return algs[i].block_size;
+		}
+	}
+	return 0;
+}
+
+METHOD(signer_t, get_signature, void,
+	private_af_alg_signer_t *this, chunk_t data, u_int8_t *buffer)
+{
+	ssize_t len;
+
+	while (this->op == -1)
+	{
+		this->op = accept(this->tfm, NULL, 0);
+		if (this->op == -1)
+		{
+			DBG1(DBG_LIB, "opening AF_ALG signer failed: %s", strerror(errno));
+			sleep(1);
+		}
+	}
+	do
+	{
+		len = send(this->op, data.ptr, data.len, buffer ? 0 : MSG_MORE);
+		if (len == -1)
+		{
+			DBG1(DBG_LIB, "writing to AF_ALG signer failed: %s", strerror(errno));
+			sleep(1);
+		}
+		else
+		{
+			data = chunk_skip(data, len);
+		}
+	}
+	while (data.len);
+	if (buffer)
+	{
+		while (read(this->op, buffer, this->block_size) != this->block_size)
+		{
+			DBG1(DBG_LIB, "reading AF_ALG signer failed: %s", strerror(errno));
+			sleep(1);
+		}
+		close(this->op);
+		this->op = -1;
+	}
+}
+
+METHOD(signer_t, allocate_signature, void,
+	private_af_alg_signer_t *this, chunk_t data, chunk_t *chunk)
+{
+	if (chunk)
+	{
+		*chunk = chunk_alloc(this->block_size);
+		get_signature(this, data, chunk->ptr);
+	}
+	else
+	{
+		get_signature(this, data, NULL);
+	}
+}
+
+METHOD(signer_t, verify_signature, bool,
+	private_af_alg_signer_t *this, chunk_t data, chunk_t signature)
+{
+	char sig[this->block_size];
+
+	if (signature.len != this->block_size)
+	{
+		return FALSE;
+	}
+	get_signature(this, data, sig);
+	return memeq(signature.ptr, sig, signature.len);
+}
+
+METHOD(signer_t, get_key_size, size_t,
+	private_af_alg_signer_t *this)
+{
+	return this->key_size;
+}
+
+METHOD(signer_t, get_block_size, size_t,
+	private_af_alg_signer_t *this)
+{
+	return this->block_size;
+}
+
+METHOD(signer_t, set_key, void,
+	private_af_alg_signer_t *this, chunk_t key)
+{
+	if (setsockopt(this->tfm, SOL_ALG, ALG_SET_KEY, key.ptr, key.len) == -1)
+	{
+		DBG1(DBG_LIB, "setting AF_ALG key failed: %s", strerror(errno));
+	}
+}
+
+METHOD(signer_t, destroy, void,
+	private_af_alg_signer_t *this)
+{
+	if (this->op != -1)
+	{
+		close(this->op);
+	}
+	close(this->tfm);
+	free(this);
+}
+
+/*
+ * Described in header
+ */
+af_alg_signer_t *af_alg_signer_create(integrity_algorithm_t algo)
+{
+	private_af_alg_signer_t *this;
+	struct sockaddr_alg sa = {
+		.salg_family = AF_ALG,
+		.salg_type = "hash",
+	};
+	size_t block_size, key_size;
+
+	block_size = lookup_alg(algo, sa.salg_name, &key_size);
+	if (!block_size)
+	{	/* not supported by kernel */
+		return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.signer = {
+				.get_signature = _get_signature,
+				.allocate_signature = _allocate_signature,
+				.verify_signature = _verify_signature,
+				.get_key_size = _get_key_size,
+				.get_block_size = _get_block_size,
+				.set_key = _set_key,
+				.destroy = _destroy,
+			},
+		},
+		.tfm = socket(AF_ALG, SOCK_SEQPACKET, 0),
+		.op = -1,
+		.block_size = block_size,
+		.key_size = key_size,
+	);
+
+	if (this->tfm == -1)
+	{
+		DBG1(DBG_LIB, "opening AF_ALG socket failed: %s", strerror(errno));
+		free(this);
+		return NULL;
+	}
+	if (bind(this->tfm, (struct sockaddr*)&sa, sizeof(sa)) == -1)
+	{
+		DBG1(DBG_LIB, "binding AF_ALG socket for '%s' failed: %s",
+			 sa.salg_name, strerror(errno));
+		destroy(this);
+		return NULL;
+	}
+	return &this->public;
+}