refactoring sources

Change-Id: Id6d52eee86b706958972e9b345ec0d4d1e488146
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

1 files changed, 358 insertions, 0 deletions

diff --git a/src/wgtpkg-digsig.c b/src/wgtpkg-digsig.c
new file mode 100644
index 0000000..284acd1
--- /dev/null
+++ b/src/wgtpkg-digsig.c
@@ -0,0 +1,358 @@
+/*
+ Copyright 2015 IoT.bzh
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+*/
+
+
+#include <string.h>
+#include <syslog.h>
+#include <assert.h>
+
+#include <libxml/parser.h>
+#include <libxml/tree.h>
+#include <libxml/uri.h>
+
+
+#include "wgtpkg.h"
+
+
+
+static const char uri_role_author[] = "http://www.w3.org/ns/widgets-digsig#role-author";
+static const char uri_role_distributor[] = "http://www.w3.org/ns/widgets-digsig#role-distributor";
+static const char uri_profile[] = "http://www.w3.org/ns/widgets-digsig#profile";
+
+
+/* global data */
+static xmlDocPtr document;  /* the document */
+
+/* facility to get the first element node (skip text nodes) starting with 'node' */
+static xmlNodePtr next_element(xmlNodePtr node)
+{
+	while (node && node->type != XML_ELEMENT_NODE)
+		node = node->next;
+	return node;
+}
+
+/* is the 'node' an element node of 'name'? */
+static int is_element(xmlNodePtr node, const char *name)
+{
+	return node->type == XML_ELEMENT_NODE
+		&& !strcmp(name, node->name);
+}
+
+/* is the 'node' an element node of 'name'? */
+static int is_node(xmlNodePtr node, const char *name)
+{
+	return node != NULL && is_element(node, name);
+}
+
+#if 0
+/* facility to get the first element node (skip text nodes) starting with 'node' */
+static xmlNodePtr next_element_type(xmlNodePtr node, const char *name)
+{
+	while (node && node->type != XML_ELEMENT_NODE && strcmp(name, node->name))
+		node = node->next;
+	return node;
+}
+
+/* search the element node of id. NOTE : not optimized at all */
+static xmlNodePtr search_for(const char *attrname, const char *value)
+{
+	char *val;
+	xmlNodePtr iter, next;
+	xmlNodePtr result;
+
+	result = NULL;
+	iter = xmlDocGetRootElement(document);
+	while (iter != NULL) {
+		val = xmlGetProp(iter, attrname);
+		if (val != NULL && !strcmp(val, value)) {
+			if (result != NULL) {
+				syslog(LOG_ERR, "duplicated %s %s", attrname, value);
+				free(val);
+				return NULL;
+			}
+			result = iter;
+		}
+		free(val);
+		next = next_element(iter->children);
+		if (next == NULL) {
+			/* no child, try sibling */
+			next = next_element(iter->next);
+			if (next == NULL) {
+				iter = iter->parent;
+				while (iter != NULL && next == NULL) {
+					next = next_element(iter->next);
+					iter = iter->parent;
+				}
+			}
+		}
+		iter = next;
+	}
+	if (result == NULL)
+		syslog(LOG_ERR, "node of %s '%s' not found", attrname, value);
+	return result;
+}
+
+/* search the element node of id. NOTE : not optimized at all */
+static xmlNodePtr search_id(const char *id)
+{
+	return search_for("Id", id);
+}
+#endif
+
+/* check the digest of one element */
+static int check_one_reference(xmlNodePtr ref)
+{
+	int rc;
+	char *uri;
+	xmlURIPtr u;
+	struct filedesc *fdesc;
+
+	/* start */
+	rc = -1;
+
+	/* get the uri */
+	uri = xmlGetProp(ref, "URI");
+	if (uri == NULL) {
+		syslog(LOG_ERR, "attribute URI of element <Reference> not found");
+		goto error;
+	}
+
+	/* parse the uri */
+	u = xmlParseURI(uri);
+	if (!u) {
+		syslog(LOG_ERR, "error while parsing URI %s", uri);
+		goto error2;
+	}
+
+	/* check that unexpected parts are not there */
+	if (u->scheme || u->opaque || u->authority || u->server || u->user || u->query) {
+		syslog(LOG_ERR, "unexpected uri component in %s", uri);
+		goto error3;
+	}
+
+	/* check path and fragment */
+	if (!u->path && !u->fragment) {
+		syslog(LOG_ERR, "invalid uri %s", uri);
+		goto error3;
+	}
+	if (u->path && u->fragment) {
+		syslog(LOG_ERR, "not allowed to sign foreign fragment in %s", uri);
+		goto error3;
+	}
+
+	if (u->path) {
+		/* check that the path is valid */
+		fdesc = file_of_name(u->path);
+		if (fdesc == NULL) {
+			syslog(LOG_ERR, "reference to unknown file %s", u->path);
+			goto error3;
+		}
+		if (fdesc->type != type_file) {
+			syslog(LOG_ERR, "reference to directory %s", u->path);
+			goto error3;
+		}
+		if ((fdesc->flags & flag_distributor_signature) != 0) {
+			syslog(LOG_ERR, "reference to signature %s", u->path);
+			goto error3;
+		}
+		fdesc->flags |= flag_referenced;
+		rc = 0;
+	} else {
+		rc = 0;
+	}
+
+error3:
+	xmlFreeURI(u);
+error2:
+	xmlFree(uri);
+error:
+	return rc;
+}
+
+static int check_references(xmlNodePtr sinfo)
+{
+	xmlNodePtr elem;
+
+	elem = sinfo->children;
+	while (elem != NULL) {
+		if (is_element(elem, "Reference"))
+			if (check_one_reference(elem))
+				return -1;
+		elem = elem->next;
+	}
+	return 0;
+}
+
+static int get_certificates(xmlNodePtr kinfo)
+{
+	xmlNodePtr n1, n2;
+	char *b;
+	int rc;
+
+	n1 = kinfo->children;
+	while (n1) {
+		if (is_element(n1, "X509Data")) {
+			n2 = n1->children;
+			while (n2) {
+				if (is_element(n2, "X509Certificate")) {
+					b = xmlNodeGetContent(n2);
+					if (b == NULL) {
+						syslog(LOG_ERR, "xmlNodeGetContent of X509Certificate failed");
+						return -1;
+					}
+					rc = add_certificate_b64(b);
+					xmlFree(b);
+					if (rc)
+						return rc;
+				}
+				n2 = n2->next;
+			}
+		}
+		n1 = n1->next;
+	}
+	return 0;
+}
+
+/* checks the current document */
+static int checkdocument()
+{
+	int rc;
+	xmlNodePtr sinfo, svalue, kinfo, objs, rootsig;
+
+	rc = -1;
+
+	rootsig = xmlDocGetRootElement(document);
+	if (!is_node(rootsig, "Signature")) {
+		syslog(LOG_ERR, "root element <Signature> not found");
+		goto error;
+	}
+
+	sinfo = next_element(rootsig->children);
+	if (!is_node(sinfo, "SignedInfo")) {
+		syslog(LOG_ERR, "element <SignedInfo> not found");
+		goto error;
+	}
+
+	svalue = next_element(sinfo->next);
+	if (!is_node(svalue, "SignatureValue")) {
+		syslog(LOG_ERR, "element <SignatureValue> not found");
+		goto error;
+	}
+
+	kinfo = next_element(svalue->next);
+	if (is_node(kinfo, "KeyInfo")) {
+		objs = kinfo->next;
+	} else {
+		objs = kinfo;
+		kinfo = NULL;
+	}
+
+	rc = check_references(sinfo);
+	if (rc)
+		goto error;
+
+	rc = xmlsec_verify(rootsig);
+	if (rc)
+		goto error;
+
+	rc = get_certificates(kinfo);
+
+error:
+	return rc;
+}
+
+/* verify the digital signature of the file described by 'fdesc' */
+int verify_digsig(struct filedesc *fdesc)
+{
+	int res;
+
+	assert ((fdesc->flags & flag_signature) != 0);
+	debug("-- checking file %s",fdesc->name);
+
+	/* reset the flags */
+	file_clear_flags();
+	clear_certificates();
+
+	/* reads and xml parses the signature file */
+	document = xmlReadFile(fdesc->name, NULL, 0);
+	if (document == NULL) {
+		syslog(LOG_ERR, "xml parse of file %s failed", fdesc->name);
+		return -1;
+	}
+
+	res = checkdocument();
+	if (res)
+		syslog(LOG_ERR, "previous error was during check of file %s", fdesc->name);
+
+	xmlFreeDoc(document);
+	return res;
+}
+
+/* check all the signature files */
+int check_all_signatures()
+{
+	int rc, irc;
+	unsigned int i, n;
+	struct filedesc *fdesc;
+
+	n = signature_count();
+	rc = 0;
+	for (i = n ; i-- > 0 ; ) {
+		fdesc = signature_of_index(i);
+		irc = verify_digsig(fdesc);
+		if (!irc)
+			rc = irc;
+	}
+
+	return rc;
+}
+
+/* create a signature of 'index' (0 for author, other values for distributors)
+using the private 'key' (filename) and the certificates 'certs' (filenames)
+as trusted chain */
+int create_digsig(int index, const char *key, const char **certs)
+{
+	struct filedesc *fdesc;
+	xmlDocPtr doc;
+	int rc, len;
+
+	rc = -1;
+
+	/* create the doc */
+	doc = xmlsec_create(index, key, certs);
+	if (doc == NULL)
+		goto error;
+
+	/* instanciate the filename */
+	fdesc = create_signature(index);
+	if (fdesc == NULL)
+		goto error2;
+
+	/* save the doc as file */
+	len = xmlSaveFormatFileEnc(fdesc->name, doc, NULL, 0);
+	if (len < 0) {
+		syslog(LOG_ERR, "xmlSaveFormatFileEnc to %s failed", fdesc->name);
+		goto error2;
+	}
+
+	rc = 0;
+error2:
+	xmlFreeDoc(doc);
+error:
+	return rc;
+}
+
+