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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef SANDBOX_LINUX_SECCOMP_BPF_VERIFIER_H__
      6 #define SANDBOX_LINUX_SECCOMP_BPF_VERIFIER_H__
      7 
      8 #include <stdint.h>
      9 
     10 #include <vector>
     11 
     12 #include "base/macros.h"
     13 
     14 struct sock_filter;
     15 
     16 namespace sandbox {
     17 struct arch_seccomp_data;
     18 class SandboxBPF;
     19 class SandboxBPFPolicy;
     20 
     21 class Verifier {
     22  public:
     23   // Evaluate the BPF program for all possible inputs and verify that it
     24   // computes the correct result. We use the "evaluators" to determine
     25   // the full set of possible inputs that we have to iterate over.
     26   // Returns success, if the BPF filter accurately reflects the rules
     27   // set by the "evaluators".
     28   // Upon success, "err" is set to NULL. Upon failure, it contains a static
     29   // error message that does not need to be free()'d.
     30   static bool VerifyBPF(SandboxBPF* sandbox,
     31                         const std::vector<struct sock_filter>& program,
     32                         const SandboxBPFPolicy& policy,
     33                         const char** err);
     34 
     35   // Evaluate a given BPF program for a particular set of system call
     36   // parameters. If evaluation failed for any reason, "err" will be set to
     37   // a non-NULL error string. Otherwise, the BPF program's result will be
     38   // returned by the function and "err" is NULL.
     39   // We do not actually implement the full BPF state machine, but only the
     40   // parts that can actually be generated by our BPF compiler. If this code
     41   // is used for purposes other than verifying the output of the sandbox's
     42   // BPF compiler, we might have to extend this BPF interpreter.
     43   static uint32_t EvaluateBPF(const std::vector<struct sock_filter>& program,
     44                               const struct arch_seccomp_data& data,
     45                               const char** err);
     46 
     47  private:
     48   DISALLOW_IMPLICIT_CONSTRUCTORS(Verifier);
     49 };
     50 
     51 }  // namespace sandbox
     52 
     53 #endif  // SANDBOX_LINUX_SECCOMP_BPF_VERIFIER_H__
     54