blob: 505015e39ceb471c304f3377948635273ec31fcb [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef SANDBOX_LINUX_SECCOMP_BPF_VERIFIER_H__
#define SANDBOX_LINUX_SECCOMP_BPF_VERIFIER_H__
#include <linux/filter.h>
#include <utility>
#include <vector>
#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
namespace playground2 {
class Verifier {
public:
// Evaluate the BPF program for all possible inputs and verify that it
// computes the correct result. We use the "evaluators" to determine
// the full set of possible inputs that we have to iterate over.
// Returns success, if the BPF filter accurately reflects the rules
// set by the "evaluators".
// Upon success, "err" is set to NULL. Upon failure, it contains a static
// error message that does not need to be free()'d.
static bool VerifyBPF(const std::vector<struct sock_filter>& program,
const Sandbox::Evaluators& evaluators,
const char **err);
// Evaluate a given BPF program for a particular set of system call
// parameters. If evaluation failed for any reason, "err" will be set to
// a non-NULL error string. Otherwise, the BPF program's result will be
// returned by the function and "err" is NULL.
// We do not actually implement the full BPF state machine, but only the
// parts that can actually be generated by our BPF compiler. If this code
// is used for purposes other than verifying the output of the sandbox's
// BPF compiler, we might have to extend this BPF interpreter.
static uint32_t EvaluateBPF(const std::vector<struct sock_filter>& program,
const struct arch_seccomp_data& data,
const char **err);
private:
struct State {
State(const std::vector<struct sock_filter>& p,
const struct arch_seccomp_data& d) :
program(p),
data(d),
ip(0),
accumulator(0),
acc_is_valid(false) {
}
const std::vector<struct sock_filter>& program;
const struct arch_seccomp_data& data;
unsigned int ip;
uint32_t accumulator;
bool acc_is_valid;
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(State);
};
static void Ld (State *state, const struct sock_filter& insn,
const char **err);
static void Jmp(State *state, const struct sock_filter& insn,
const char **err);
static uint32_t Ret(State *state, const struct sock_filter& insn,
const char **err);
DISALLOW_IMPLICIT_CONSTRUCTORS(Verifier);
};
} // namespace
#endif // SANDBOX_LINUX_SECCOMP_BPF_VERIFIER_H__