summaryrefslogtreecommitdiff
path: root/src/libipsec/esp_context.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/libipsec/esp_context.c')
-rw-r--r--src/libipsec/esp_context.c301
1 files changed, 301 insertions, 0 deletions
diff --git a/src/libipsec/esp_context.c b/src/libipsec/esp_context.c
new file mode 100644
index 000000000..dc3ad3f8b
--- /dev/null
+++ b/src/libipsec/esp_context.c
@@ -0,0 +1,301 @@
+/*
+ * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012 Giuliano Grassi
+ * Copyright (C) 2012 Ralf Sager
+ * Hochschule fuer Technik Rapperswil
+ *
+ * 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 <limits.h>
+#include <stdint.h>
+
+#include "esp_context.h"
+
+#include <library.h>
+#include <debug.h>
+#include <crypto/crypters/crypter.h>
+#include <crypto/signers/signer.h>
+
+/**
+ * Should be a multiple of 8
+ */
+#define ESP_DEFAULT_WINDOW_SIZE 128
+
+typedef struct private_esp_context_t private_esp_context_t;
+
+/**
+ * Private additions to esp_context_t.
+ */
+struct private_esp_context_t {
+
+ /**
+ * Public members
+ */
+ esp_context_t public;
+
+ /**
+ * Crypter used to encrypt/decrypt ESP packets
+ */
+ crypter_t *crypter;
+
+ /**
+ * Signer to authenticate ESP packets
+ */
+ signer_t *signer;
+
+ /**
+ * The highest sequence number that was successfully verified
+ * and authenticated, or assigned in an outbound context
+ */
+ u_int32_t last_seqno;
+
+ /**
+ * The bit in the window of the highest authenticated sequence number
+ */
+ u_int seqno_index;
+
+ /**
+ * The size of the anti-replay window (in bits)
+ */
+ u_int window_size;
+
+ /**
+ * The anti-replay window buffer
+ */
+ chunk_t window;
+
+ /**
+ * TRUE in case of an inbound ESP context
+ */
+ bool inbound;
+};
+
+/**
+ * Set or unset a bit in the window.
+ */
+static inline void set_window_bit(private_esp_context_t *this,
+ u_int index, bool set)
+{
+ u_int i = index / CHAR_BIT;
+
+ if (set)
+ {
+ this->window.ptr[i] |= 1 << (index % CHAR_BIT);
+ }
+ else
+ {
+ this->window.ptr[i] &= ~(1 << (index % CHAR_BIT));
+ }
+}
+
+/**
+ * Get a bit from the window.
+ */
+static inline bool get_window_bit(private_esp_context_t *this, u_int index)
+{
+ u_int i = index / CHAR_BIT;
+
+ return this->window.ptr[i] & (1 << index % CHAR_BIT);
+}
+
+/**
+ * Returns TRUE if the supplied seqno is not already marked in the window
+ */
+static bool check_window(private_esp_context_t *this, u_int32_t seqno)
+{
+ u_int offset;
+
+ offset = this->last_seqno - seqno;
+ offset = (this->seqno_index - offset) % this->window_size;
+ return !get_window_bit(this, offset);
+}
+
+METHOD(esp_context_t, verify_seqno, bool,
+ private_esp_context_t *this, u_int32_t seqno)
+{
+ if (!this->inbound)
+ {
+ return FALSE;
+ }
+
+ if (seqno > this->last_seqno)
+ { /* |----------------------------------------|
+ * <---------^ ^ or <---------^ ^
+ * WIN H S WIN H S
+ */
+ return TRUE;
+ }
+ else if (seqno > 0 && this->window_size > this->last_seqno - seqno)
+ { /* |----------------------------------------|
+ * <---------^ or <---------^
+ * WIN ^ H WIN ^ H
+ * S S
+ */
+ return check_window(this, seqno);
+ }
+ else
+ { /* |----------------------------------------|
+ * ^ <---------^
+ * S WIN H
+ */
+ return FALSE;
+ }
+}
+
+METHOD(esp_context_t, set_authenticated_seqno, void,
+ private_esp_context_t *this, u_int32_t seqno)
+{
+ u_int i, shift;
+
+ if (!this->inbound)
+ {
+ return;
+ }
+
+ if (seqno > this->last_seqno)
+ { /* shift the window to the new highest authenticated seqno */
+ shift = seqno - this->last_seqno;
+ shift = shift < this->window_size ? shift : this->window_size;
+ for (i = 0; i < shift; ++i)
+ {
+ this->seqno_index = (this->seqno_index + 1) % this->window_size;
+ set_window_bit(this, this->seqno_index, FALSE);
+ }
+ set_window_bit(this, this->seqno_index, TRUE);
+ this->last_seqno = seqno;
+ }
+ else
+ { /* seqno is inside the window, set the corresponding window bit */
+ i = this->last_seqno - seqno;
+ set_window_bit(this, (this->seqno_index - i) % this->window_size, TRUE);
+ }
+}
+
+METHOD(esp_context_t, get_seqno, u_int32_t,
+ private_esp_context_t *this)
+{
+ return this->last_seqno;
+}
+
+METHOD(esp_context_t, next_seqno, bool,
+ private_esp_context_t *this, u_int32_t *seqno)
+{
+ if (this->inbound || this->last_seqno == UINT32_MAX)
+ { /* inbound or segno would cycle */
+ return FALSE;
+ }
+ *seqno = ++this->last_seqno;
+ return TRUE;
+}
+
+METHOD(esp_context_t, get_signer, signer_t *,
+ private_esp_context_t *this)
+{
+ return this->signer;
+}
+
+METHOD(esp_context_t, get_crypter, crypter_t *,
+ private_esp_context_t *this)
+{
+ return this->crypter;
+}
+
+METHOD(esp_context_t, destroy, void,
+ private_esp_context_t *this)
+{
+ chunk_free(&this->window);
+ DESTROY_IF(this->crypter);
+ DESTROY_IF(this->signer);
+ free(this);
+}
+
+/**
+ * Described in header.
+ */
+esp_context_t *esp_context_create(int enc_alg, chunk_t enc_key,
+ int int_alg, chunk_t int_key, bool inbound)
+{
+ private_esp_context_t *this;
+
+ INIT(this,
+ .public = {
+ .get_crypter = _get_crypter,
+ .get_signer = _get_signer,
+ .get_seqno = _get_seqno,
+ .next_seqno = _next_seqno,
+ .verify_seqno = _verify_seqno,
+ .set_authenticated_seqno = _set_authenticated_seqno,
+ .destroy = _destroy,
+ },
+ .inbound = inbound,
+ .window_size = ESP_DEFAULT_WINDOW_SIZE,
+ );
+
+ switch(enc_alg)
+ {
+ case ENCR_AES_CBC:
+ this->crypter = lib->crypto->create_crypter(lib->crypto, enc_alg,
+ enc_key.len);
+ break;
+ default:
+ break;
+ }
+ if (!this->crypter)
+ {
+ DBG1(DBG_ESP, "failed to create ESP context: unsupported encryption "
+ "algorithm");
+ destroy(this);
+ return NULL;
+ }
+ if (!this->crypter->set_key(this->crypter, enc_key))
+ {
+ DBG1(DBG_ESP, "failed to create ESP context: setting encryption key "
+ "failed");
+ destroy(this);
+ return NULL;
+ }
+
+ switch(int_alg)
+ {
+ case AUTH_HMAC_SHA1_96:
+ case AUTH_HMAC_SHA2_256_128:
+ case AUTH_HMAC_SHA2_384_192:
+ case AUTH_HMAC_SHA2_512_256:
+ this->signer = lib->crypto->create_signer(lib->crypto, int_alg);
+ break;
+ default:
+ break;
+ }
+ if (!this->signer)
+ {
+ DBG1(DBG_ESP, "failed to create ESP context: unsupported integrity "
+ "algorithm");
+ destroy(this);
+ return NULL;
+ }
+ if (!this->signer->set_key(this->signer, int_key))
+ {
+ DBG1(DBG_ESP, "failed to create ESP context: setting signature key "
+ "failed");
+ destroy(this);
+ return NULL;
+ }
+
+ if (inbound)
+ {
+ this->window = chunk_alloc(this->window_size / CHAR_BIT + 1);
+ memset(this->window.ptr, 0, this->window.len);
+ }
+ return &this->public;
+}
+
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-13 03:24:37 +0000