xml.c

/*
 * xml parsing routines
 *
 * Copyright (C) 2014-2018 LastPass.
 *
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 *
 * You must obey the GNU General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
 * version of the file(s), but you are not obligated to do so.  If you
 * do not wish to do so, delete this exception statement from your
 * version.  If you delete this exception statement from all source
 * files in the program, then also delete it here.
 *
 * See LICENSE.OpenSSL for more details regarding this exception.
 */
#include "xml.h"
#include "util.h"
#include "blob.h"
#include <string.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <errno.h>

struct session *xml_ok_session(const char *buf, unsigned const char key[KDF_HASH_LEN])
{
	struct session *session = NULL;
	xmlDoc *doc = NULL;
	xmlNode *root;
	doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	if (!doc)
		goto out;

	root = xmlDocGetRootElement(doc);
	if (root && !xmlStrcmp(root->name, BAD_CAST "response")) {
		for (root = root->children; root; root = root->next) {
			if (!xmlStrcmp(root->name, BAD_CAST "ok"))
				break;
		}
	}
	if (root && !xmlStrcmp(root->name, BAD_CAST "ok")) {
		session = session_new();
		for (xmlAttrPtr attr = root->properties; attr; attr = attr->next) {
			if (!xmlStrcmp(attr->name, BAD_CAST "uid"))
				session->uid = (char *)xmlNodeListGetString(doc, attr->children, 1);
			if (!xmlStrcmp(attr->name, BAD_CAST "sessionid"))
				session->sessionid = (char *)xmlNodeListGetString(doc, attr->children, 1);
			if (!xmlStrcmp(attr->name, BAD_CAST "token"))
				session->token = (char *)xmlNodeListGetString(doc, attr->children, 1);
			if (!xmlStrcmp(attr->name, BAD_CAST "privatekeyenc")) {
				_cleanup_free_ char *private_key = (char *)xmlNodeListGetString(doc, attr->children, 1);
				session_set_private_key(session, key, private_key);
			}
		}
	}
out:
	if (doc)
		xmlFreeDoc(doc);
	if (!session_is_valid(session)) {
		session_free(session);
		return NULL;
	}
	return session;
}

unsigned long long xml_login_check(const char *buf, struct session *session)
{
	_cleanup_free_ char *versionstr = NULL;
	unsigned long long version = 0;
	xmlDoc *doc = NULL;
	xmlNode *root, *child = NULL;

	doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	if (!doc)
		goto out;

	root = xmlDocGetRootElement(doc);
	if (root && !xmlStrcmp(root->name, BAD_CAST "response")) {
		for (child = root->children; child; child = child->next) {
			if (!xmlStrcmp(child->name, BAD_CAST "ok"))
				break;
		}
	}
	if (child) {
		for (xmlAttrPtr attr = child->properties; attr; attr = attr->next) {
			if (!xmlStrcmp(attr->name, BAD_CAST "uid")) {
				free(session->uid);
				session->uid = (char *)xmlNodeListGetString(doc, attr->children, 1);
			} else if (!xmlStrcmp(attr->name, BAD_CAST "sessionid")) {
				free(session->sessionid);
				session->sessionid = (char *)xmlNodeListGetString(doc, attr->children, 1);
			} else if (!xmlStrcmp(attr->name, BAD_CAST "token")) {
				free(session->token);
				session->token = (char *)xmlNodeListGetString(doc, attr->children, 1);
			} else if (!xmlStrcmp(attr->name, BAD_CAST "accts_version")) {
				versionstr = (char *)xmlNodeListGetString(doc, attr->children, 1);
				version = strtoull(versionstr, NULL, 10);
			}
		}
	}
out:
	if (doc)
		xmlFreeDoc(doc);
	return version;
}

char *xml_error_cause(const char *buf, const char *what)
{
	char *result = NULL;
	xmlDoc *doc = NULL;
	xmlNode *root;

	doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	if (!doc)
		goto out;

	root = xmlDocGetRootElement(doc);
	if (root && !xmlStrcmp(root->name, BAD_CAST "response")) {
		for (xmlNode *child = root->children; child; child = child->next) {
			if (!xmlStrcmp(child->name, BAD_CAST "error")) {
				for (xmlAttrPtr attr = child->properties; attr; attr = attr->next) {
					if (!xmlStrcmp(attr->name, BAD_CAST what)) {
						result = (char *)xmlNodeListGetString(doc, attr->children, 1);
						goto out;
					}
				}
				break;
			}
		}
	}
out:
	if (doc)
		xmlFreeDoc(doc);
	if (!result)
		result = xstrdup("unknown");

	return result;
}

/*
 * Check if node has the tag "name", and interpret as a string
 * if so.
 *
 * Return true and update the string pointed to by ptr if the node
 * matches name.
 */
static bool
xml_parse_str(xmlDoc *doc, xmlNode *parent, const char *name, char **ptr)
{
	if (xmlStrcmp(parent->name, BAD_CAST name))
		return false;

	*ptr = (char *) xmlNodeListGetString(doc, parent->xmlChildrenNode, 1);
	if (!*ptr)
		return false;

	return true;
}

/*
 * Check if node has the tag "name", and interpret as an int if so.
 *
 * Return true and update the int pointed to by ptr if the node
 * matches name.
 */
static bool
xml_parse_int(xmlDoc *doc, xmlNode *parent, const char *name, int *ptr)
{
	if (xmlStrcmp(parent->name, BAD_CAST name))
		return false;

	_cleanup_free_ char *str = (char *)
		xmlNodeListGetString(doc, parent->xmlChildrenNode, 1);

	if (!str)
		return false;

	*ptr = atoi(str);
	return true;
}

/*
 * Check if node is for the boolean "name", and interpret as a boolean
 * if so.
 *
 * Return true and update the boolean pointed to by ptr if the node
 * matches name.
 */
static bool
xml_parse_bool(xmlDoc *doc, xmlNode *parent, const char *name, bool *ptr)
{
	int intval;

	if (!xml_parse_int(doc, parent, name, &intval))
		return false;

	*ptr = intval;
	return true;
}

static void
xml_parse_share_permissions(xmlDoc *doc, xmlNode *item, struct share_user *user)
{
	bool tmp;

	for (xmlNode *child = item->children; child; child = child->next) {
		if (xml_parse_bool(doc, child, "canadminister", &user->admin))
			continue;
		if (xml_parse_bool(doc, child, "readonly", &user->read_only))
			continue;
		if (xml_parse_bool(doc, child, "give", &tmp)) {
			user->hide_passwords = !tmp;
			continue;
		}
	}
}

static void
xml_parse_share_user(xmlDoc *doc, xmlNode *item, struct share_user *user)
{
	char *tmp;

	/* process a user item */
	for (xmlNode *child = item->children; child; child = child->next) {
		if (xml_parse_str(doc, child, "realname", &user->realname))
			continue;
		if (xml_parse_str(doc, child, "username", &user->username))
			continue;
		if (xml_parse_str(doc, child, "uid", &user->uid))
			continue;
		if (xml_parse_bool(doc, child, "group", &user->is_group))
			continue;
		if (xml_parse_bool(doc, child, "outsideenterprise", &user->outside_enterprise))
			continue;
		if (xml_parse_bool(doc, child, "accepted", &user->accepted))
			continue;
		if (xml_parse_str(doc, child, "sharingkey", &tmp)) {
			int ret = hex_to_bytes(tmp, &user->sharing_key.key);
			if (ret == 0)
				user->sharing_key.len = strlen(tmp) / 2;
			free(tmp);
			continue;
		}
		if (!xmlStrcmp(child->name, BAD_CAST "permissions"))
			xml_parse_share_permissions(doc, child, user);
	}
}

static int
xml_parse_share_key_entry(xmlDoc *doc, xmlNode *root,
			  struct share_user *user, int idx)
{
	char *tmp;

	_cleanup_free_ char *pubkey = NULL;
	_cleanup_free_ char *username = NULL;
	_cleanup_free_ char *uid = NULL;
	_cleanup_free_ char *cgid = NULL;

	xasprintf(&pubkey, "pubkey%d", idx);
	xasprintf(&username, "username%d", idx);
	xasprintf(&uid, "uid%d", idx);
	xasprintf(&cgid, "cgid%d", idx);

	memset(user, 0, sizeof(*user));

	for (xmlNode *item = root->children; item; item = item->next) {
		if (xml_parse_str(doc, item, pubkey, &tmp)) {
			int ret = hex_to_bytes(tmp, &user->sharing_key.key);
			if (ret == 0)
				user->sharing_key.len = strlen(tmp) / 2;
			free(tmp);
			continue;
		}
		if (xml_parse_str(doc, item, username, &user->username))
			continue;
		if (xml_parse_str(doc, item, uid, &user->uid))
			continue;
		if (xml_parse_str(doc, item, cgid, &user->cgid))
			continue;
	}

	if (!user->uid) {
		free(user->cgid);
		free(user->username);
		free(user->sharing_key.key);
		return -ENOENT;
	}
	return 0;
}


int xml_parse_share_getinfo(const char *buf, struct list_head *users)
{
	int ret;
	xmlDoc *doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	if (!doc)
		return -EINVAL;

	/*
	 * XML fields are as follows:
	 * xmlresponse
	 *   users
	 *     item
	 *       realname
	 *       uid
	 *       group
	 *       username
	 *       permissions
	 *         readonly
	 *         canadminister
	 *         give
	 *       outsideenterprise
	 *       accepted
	 *     item...
	 */
	xmlNode *root = xmlDocGetRootElement(doc);
	if (!root ||
	    xmlStrcmp(root->name, BAD_CAST "xmlresponse") ||
	    !root->children ||
	    xmlStrcmp(root->children->name, BAD_CAST "users")) {
		ret = -EINVAL;
		goto free_doc;
	}

	xmlNode *usernode = root->children;
	for (xmlNode *item = usernode->children; item; item = item->next) {
		if (xmlStrcmp(item->name, BAD_CAST "item"))
			continue;

		struct share_user *new_user = xcalloc(1, sizeof(*new_user));
		xml_parse_share_user(doc, item, new_user);
		list_add_tail(&new_user->list, users);
	}
	ret = 0;
free_doc:
	xmlFreeDoc(doc);
	return ret;
}

int xml_parse_share_getpubkeys(const char *buf, struct list_head *user_list)
{
	int ret;
	xmlDoc *doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	if (!doc)
		return -EINVAL;

	/*
	 * XML fields are as follows:
	 * xmlresponse
	 *   success
	 *   pubkey0
	 *   uid0
	 *   username0
	 *   cgid0 (if group)
	 */
	xmlNode *root = xmlDocGetRootElement(doc);
	if (!root || xmlStrcmp(root->name, BAD_CAST "xmlresponse") ||
	    !root->children) {
		ret = -EINVAL;
		goto free_doc;
	}

	for (int count = 0; ; count++) {
		struct share_user *user = new0(struct share_user, 1);
		ret = xml_parse_share_key_entry(doc, root, user, count);
		if (ret) {
			free(user);
			break;
		}
		list_add(&user->list, user_list);
	}
	if (list_empty(user_list))
		ret = -ENOENT;
	else
		ret = 0;
free_doc:
	xmlFreeDoc(doc);
	return ret;
}

static
int xml_parse_su_key_entry(xmlDoc *doc, xmlNode *parent,
			   struct pwchange_su_key *su_key, int idx)
{
	char *tmp;
	_cleanup_free_ char *pubkey = NULL;
	_cleanup_free_ char *uid = NULL;

	xasprintf(&pubkey, "sukey%d", idx);
	xasprintf(&uid, "suuid%d", idx);

	memset(su_key, 0, sizeof(*su_key));
	for (xmlAttrPtr attr = parent->properties; attr; attr = attr->next) {
		if (!xmlStrcmp(attr->name, BAD_CAST pubkey)) {
			tmp = (char *) xmlNodeListGetString(doc, attr->children, 1);
			int ret = hex_to_bytes(tmp, &su_key->sharing_key.key);
			if (ret == 0)
				su_key->sharing_key.len = strlen(tmp) / 2;
			free(tmp);
			continue;
		}
		if (!xmlStrcmp(attr->name, BAD_CAST uid)) {
			tmp = (char *) xmlNodeListGetString(doc, attr->children, 1);
			su_key->uid = tmp;
			continue;
		}
	}
	if (!su_key->sharing_key.len || !su_key->uid) {
		free(su_key->uid);
		free(su_key->sharing_key.key);
		return -ENOENT;
	}
	return 0;
}

static
int xml_parse_pwchange_su_keys(xmlDoc *doc, xmlNode *parent,
			       struct pwchange_info *info)
{
	for (int count = 0; ; count++) {
		struct pwchange_su_key *su_key = new0(struct pwchange_su_key,1);
		int ret = xml_parse_su_key_entry(doc, parent, su_key, count);
		if (ret) {
			free(su_key);
			break;
		}
		list_add(&su_key->list, &info->su_keys);
	}
	return 0;
}

static
int xml_parse_pwchange_data(char *data, struct pwchange_info *info)
{
	char *token, *end;
	struct pwchange_field *field;

	/*
	 * read the first two lines without strtok: in case there are
	 * empty lines we don't want to skip them.
	 */
#define next_line(x) { \
	end = strchr(data, '\n'); \
	if (!end) \
		return -ENOENT; \
	*end++ = 0; \
	info->x = xstrdup(data); \
	data = end; \
}
	next_line(reencrypt_id);
	next_line(privkey_encrypted);

#undef next_line

	for (token = strtok(data, "\n"); token; token = strtok(NULL, "\n")) {

		if (!strncmp(token, "endmarker", 9))
			break;

		field = new0(struct pwchange_field, 1);

		char *delim = strchr(token, '\t');
		if (delim) {
			*delim = 0;
			field->optional = *(delim + 1) == '0';
		}
		field->old_ctext = xstrdup(token);
		list_add_tail(&field->list, &info->fields);
	}
	return 0;
}

int xml_api_err(const char *buf)
{
	int ret;
	xmlDoc *doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	xmlNode *root = xmlDocGetRootElement(doc);
	if (!root || xmlStrcmp(root->name, BAD_CAST "lastpass") ||
			       !root->children) {
		ret = -EINVAL;
		goto free_doc;
	}

	for (xmlAttrPtr attr = root->properties; attr; attr = attr->next) {
		if (!xmlStrcmp(attr->name, BAD_CAST "rc")) {
			_cleanup_free_ char *val = (char *)
				xmlNodeListGetString(doc, attr->children, 1);
			if (strcmp(val, "OK") != 0) {
				ret = -EPERM;
				goto free_doc;
			}
		}
	}
	ret = 0;
free_doc:
	xmlFreeDoc(doc);
	return ret;
}

int xml_parse_pwchange(const char *buf, struct pwchange_info *info)
{
	int ret;
	xmlDoc *doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	INIT_LIST_HEAD(&info->fields);
	INIT_LIST_HEAD(&info->su_keys);

	xmlNode *root = xmlDocGetRootElement(doc);
	if (!root || xmlStrcmp(root->name, BAD_CAST "lastpass") ||
			       !root->children) {
		ret = -EINVAL;
		goto free_doc;
	}

	for (xmlAttrPtr attr = root->properties; attr; attr = attr->next) {
		if (!xmlStrcmp(attr->name, BAD_CAST "rc")) {
			_cleanup_free_ char *val = (char *)
				xmlNodeListGetString(doc, attr->children, 1);
			if (strcmp(val, "OK") != 0) {
				ret = -EPERM;
				goto free_doc;
			}
		}
	}

	for (xmlNode *item = root->children; item; item = item->next) {
		if (xmlStrcmp(item->name, BAD_CAST "data"))
			continue;

		for (xmlAttrPtr attr = item->properties; attr; attr = attr->next) {
			if (!xmlStrcmp(attr->name, BAD_CAST "xml")) {
				_cleanup_free_ char *data = (char *)
					xmlNodeListGetString(doc, attr->children, 1);

				ret = xml_parse_pwchange_data(data, info);
				if (ret)
					goto free_doc;
			}
			if (!xmlStrcmp(attr->name, BAD_CAST "token"))
				info->token = (char *)xmlNodeListGetString(doc, attr->children, 1);
		}
		xml_parse_pwchange_su_keys(doc, item, info);
	}

	ret = 0;
free_doc:
	xmlFreeDoc(doc);
	return ret;
}

int xml_parse_share_getpubkey(const char *buf, struct share_user *user)
{
	struct list_head users;
	struct share_user *share_user, *tmp;
	int ret;

	INIT_LIST_HEAD(&users);
	ret = xml_parse_share_getpubkeys(buf, &users);
	if (ret)
		return ret;

	if (list_empty(&users))
		return -ENOENT;

	share_user = list_first_entry(&users, struct share_user, list);
	*user = *share_user;

	list_for_each_entry_safe(share_user, tmp, &users, list)
		free(share_user);

	return 0;
}

static
void xml_parse_share_limit_aids(xmlDoc *doc, xmlNode *parent,
				struct list_head *list)
{
	for (xmlNode *item = parent->children; item; item = item->next) {
		if (xmlStrncmp(item->name, BAD_CAST "aid", 3))
			continue;

		struct share_limit_aid *aid = new0(struct share_limit_aid, 1);

		aid->aid = (char *) xmlNodeListGetString(doc,
				item->xmlChildrenNode, 1);

		list_add_tail(&aid->list, list);
	}
}

int xml_parse_share_get_limits(const char *buf, struct share_limit *limit)
{
	int ret;

	memset(limit, 0, sizeof(*limit));
	INIT_LIST_HEAD(&limit->aid_list);

	xmlDoc *doc = xmlReadMemory(buf, strlen(buf), NULL, NULL, 0);

	if (!doc)
		return -EINVAL;

	xmlNode *root = xmlDocGetRootElement(doc);
	if (!root || xmlStrcmp(root->name, BAD_CAST "xmlresponse") ||
	    !root->children) {
		ret = -EINVAL;
		goto free_doc;
	}

	for (xmlNode *item = root->children; item; item = item->next) {
		if (xml_parse_bool(doc, item, "hidebydefault",
				   &limit->whitelist))
			continue;

		if (!xmlStrcmp(item->name, BAD_CAST "aids")) {
			xml_parse_share_limit_aids(doc, item, &limit->aid_list);
		}
	}
	ret = 0;
free_doc:
	xmlFreeDoc(doc);
	return ret;
}