content/common/sandbox_linux/bpf_renderer_policy_linux.cc

// Copyright 2013 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.

#include "content/common/sandbox_linux/bpf_renderer_policy_linux.h"

#include <errno.h>
#include <sys/ioctl.h>

#include "build/build_config.h"
#include "content/common/sandbox_linux/sandbox_linux.h"
#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
#include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h"
#include "sandbox/linux/seccomp-bpf-helpers/syscall_parameters_restrictions.h"
#include "sandbox/linux/seccomp-bpf-helpers/syscall_sets.h"
#include "sandbox/linux/system_headers/linux_syscalls.h"

#if defined(OS_CHROMEOS)
// TODO(vignatti): replace the local definitions below with #include
// <linux/dma-buf.h> once kernel version 4.6 becomes widely used.
#include <linux/types.h>

struct local_dma_buf_sync {
  __u64 flags;
};
#define LOCAL_DMA_BUF_BASE 'b'
#define LOCAL_DMA_BUF_IOCTL_SYNC \
  _IOW(LOCAL_DMA_BUF_BASE, 0, struct local_dma_buf_sync)
#endif

using sandbox::SyscallSets;
using sandbox::bpf_dsl::Allow;
using sandbox::bpf_dsl::Arg;
using sandbox::bpf_dsl::Error;
using sandbox::bpf_dsl::ResultExpr;

namespace content {

namespace {

ResultExpr RestrictIoctl() {
  const Arg<unsigned long> request(1);
  return Switch(request)
      .SANDBOX_BPF_DSL_CASES((static_cast<unsigned long>(TCGETS), FIONREAD),
                             Allow())
#if defined(OS_CHROMEOS)
      .SANDBOX_BPF_DSL_CASES(
          (static_cast<unsigned long>(LOCAL_DMA_BUF_IOCTL_SYNC)), Allow())
#endif
      .Default(sandbox::CrashSIGSYSIoctl());
}

}  // namespace

RendererProcessPolicy::RendererProcessPolicy() {}
RendererProcessPolicy::~RendererProcessPolicy() {}

ResultExpr RendererProcessPolicy::EvaluateSyscall(int sysno) const {
  switch (sysno) {
    // The baseline policy allows __NR_clock_gettime. Allow
    // clock_getres() for V8. crbug.com/329053.
    case __NR_clock_getres:
      return sandbox::RestrictClockID();
    case __NR_ioctl:
      return RestrictIoctl();
    // Allow the system calls below.
    case __NR_fdatasync:
    case __NR_fsync:
#if defined(__i386__) || defined(__x86_64__) || defined(__mips__) || \
    defined(__aarch64__)
    case __NR_getrlimit:
    case __NR_setrlimit:
// We allow setrlimit to dynamically adjust the address space limit as
// needed for WebAssembly memory objects (https://crbug.com/750378). Even
// with setrlimit being allowed, we cannot raise rlim_max once it's
// lowered. Thus we generally have the same protection because we normally
// set rlim_max and rlim_cur together.
//
// See SandboxLinux::LimitAddressSpace() in
// content/common/sandbox_linux/sandbox_linux.cc and
// ArrayBufferContents::ReserveMemory,
// ArrayBufferContents::ReleaseReservedMemory in
// third_party/WebKit/Source/platform/wtf/typed_arrays/ArrayBufferContents.cpp.
#endif
#if defined(__i386__) || defined(__arm__)
    case __NR_ugetrlimit:
#endif
    case __NR_mremap:  // See crbug.com/149834.
    case __NR_pread64:
    case __NR_pwrite64:
    case __NR_sched_get_priority_max:
    case __NR_sched_get_priority_min:
    case __NR_sysinfo:
    case __NR_times:
    case __NR_uname:
      return Allow();
    case __NR_sched_getaffinity:
    case __NR_sched_getparam:
    case __NR_sched_getscheduler:
    case __NR_sched_setscheduler:
      return sandbox::RestrictSchedTarget(GetPolicyPid(), sysno);
    case __NR_prlimit64:
      // See crbug.com/662450 and setrlimit comment above.
      return sandbox::RestrictPrlimit(GetPolicyPid());
    default:
      // Default on the content baseline policy.
      return SandboxBPFBasePolicy::EvaluateSyscall(sysno);
  }
}

}  // namespace content