apparmor/parser/userns.cc

/*
 *   Copyright (c) 2022
 *   Canonical, Ltd. (All rights reserved)
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of version 2 of the GNU General Public
 *   License published by the Free Software Foundation.
 *
 *   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, contact Novell, Inc. or Canonical
 *   Ltd.
 */

#include "parser.h"
#include "profile.h"
#include "userns.h"

#include <iomanip>
#include <string>
#include <iostream>
#include <sstream>

void userns_rule::move_conditionals(struct cond_entry *conds)
{
	struct cond_entry *cond_ent;

	list_for_each(conds, cond_ent) {
		/* for now disallow keyword 'in' (list) */
		if (!cond_ent->eq)
			yyerror("keyword \"in\" is not allowed in userns rules\n");

		/* no valid conditionals atm */
		yyerror("invalid userns rule conditional \"%s\"\n",
			cond_ent->name);
	}
}

userns_rule::userns_rule(int mode_p, struct cond_entry *conds):
	audit(0), deny(0)
{
	if (mode_p) {
		if (mode_p & ~AA_VALID_USERNS_PERMS)
			yyerror("mode contains invalid permissions for userns\n");
		mode = mode_p;

	} else {
		/* default to all perms */
		mode = AA_VALID_USERNS_PERMS;
	}

	move_conditionals(conds);
	free_cond_list(conds);
}

ostream &userns_rule::dump(ostream &os)
{
	if (audit)
		os << "audit ";
	if (deny)
		os << "deny ";

	os << "userns ";

	if (mode != AA_VALID_USERNS_PERMS) {
		if (mode & AA_USERNS_CREATE)
			os << "create ";
	}

	os << ",\n";

	return os;
}


int userns_rule::expand_variables(void)
{
	return 0;
}

void userns_rule::warn_once(const char *name)
{
	rule_t::warn_once(name, "userns rules not enforced");
}

int userns_rule::gen_policy_re(Profile &prof)
{
	std::ostringstream buffer;
	std::string buf;

	if (!features_supports_userns) {
		warn_once(prof.name);
		return RULE_NOT_SUPPORTED;
	}

	buffer << "\\x" << std::setfill('0') << std::setw(2) << std::hex << AA_CLASS_NS;
	buf = buffer.str();
	if (mode & AA_VALID_USERNS_PERMS) {
		if (!prof.policy.rules->add_rule(buf.c_str(), deny, mode, audit,
						 dfaflags))
			goto fail;
	}

	return RULE_OK;

fail:
	return RULE_ERROR;
}