app/blk_shred: fill a block device with noise
The blk_shred utitity write over an entire Block session region with noise suitable as a ciphertext background. See the 'sequence' utility for making multiple write passes. Fix #81
This commit is contained in:
Emery Hemingway
committed by
Norman Feske
Norman Feske
parent
a7e6bf698d
commit
065f58af22
75
run/blk_shred.run
Normal file
75
run/blk_shred.run
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#
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# \brief Scenario to wipe hard drive in target machine
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# \author Emery Hemingway
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# \date 2017-08-26
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#
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#
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# Build
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#
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set build_components { app/blk_shred }
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source ${genode_dir}/repos/base/run/platform_drv.inc
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append_platform_drv_build_components
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build $build_components
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create_boot_directory
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import_from_depot \
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genodelabs/src/[base_src] \
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genodelabs/src/init \
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genodelabs/src/ahci_drv \
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#
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# Generate config
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#
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set config {
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<config>
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<parent-provides>
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<service name="ROM"/>
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<service name="IRQ"/>
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<service name="IO_MEM"/>
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<service name="IO_PORT"/>
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<service name="PD"/>
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<service name="RM"/>
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<service name="CPU"/>
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<service name="LOG"/>
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</parent-provides>
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<default-route>
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<any-service> <parent/> <any-child/> </any-service>
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</default-route>
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<default caps="100"/>
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<start name="timer">
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<resource name="RAM" quantum="1M" />
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<provides><service name="Timer" /></provides>
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</start>}
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append_platform_drv_config
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append config {
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<start name="ahci_drv">
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<resource name="RAM" quantum="2M" />
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<provides><service name="Block" /></provides>
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<config>
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<policy label_prefix="blk_shred" device="0" writeable="yes"/>
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</config>
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</start>
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<start name="blk_shred">
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<resource name="RAM" quantum="4M" />
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</start>
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</config> }
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install_config $config
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#
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# Boot modules
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#
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set boot_modules { blk_shred }
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append_platform_drv_boot_modules
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build_boot_image $boot_modules
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run_genode_until forever
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277
src/app/blk_shred/main.cc
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277
src/app/blk_shred/main.cc
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/*
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* \brief Block shredder
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* \author Emery Hemingway
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* \date 2017-08-26
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*/
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/*
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* Copyright (C) 2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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/**
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* TODO:
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* - Progress report
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*/
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/* Genode includes */
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#include <block_session/connection.h>
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#include <timer_session/connection.h>
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#include <base/heap.h>
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#include <base/component.h>
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#include <base/sleep.h>
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/* Jitterentropy includes */
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#include <jitterentropy.h>
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/* PCG includes */
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#include <pcg_variants.h>
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namespace Blk_shred {
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using namespace Genode;
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using namespace Block;
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struct Main;
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enum {
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/* XXX: part_blk has a fixed backend buffer that limits our packet size */
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PKT_SIZE = 1 << 20,
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PKT_BUF_SIZE = PKT_SIZE*2 + (32<<10)
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};
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uint64_t pcg_init[2] = PCG32_INITIALIZER;
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}
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struct Blk_shred::Main
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{
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Genode::Env &env;
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Timer::Connection timer { env };
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Heap heap { env.pd(), env.rm() };
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Allocator_avl packet_alloc { &heap };
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Block::Connection blk {
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env, &packet_alloc, PKT_BUF_SIZE };
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Block::Session::Tx::Source &pkt_source = *blk.tx();
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size_t blk_size = 0;
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Block::sector_t blk_total= 0;
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rand_data *jent;
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pcg32_random_t pcg;
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template <typename... ARGS>
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void die(ARGS &&... args)
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{
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/* wipe noise state */
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seed_noise();
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error(args...);
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env.parent().exit(~0);
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sleep_forever();
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}
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void seed_noise()
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{
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/* read entropy into initialization variables */
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jent_read_entropy(jent, (char*)&pcg_init, sizeof(pcg_init));
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pcg_init[1] |= 1;
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pcg32_srandom_r(&pcg, pcg_init[0], pcg_init[1]);
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}
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Main(Genode::Env &env) : env(env)
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{
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/***********************
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** Seed noise source **
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***********************/
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jitterentropy_init(heap);
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if (jent_entropy_init() != 0)
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die("jitterentropy library could not be initialized!");
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jent = jent_entropy_collector_alloc(0, 0);
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if (!jent)
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die("jitterentropy could not allocate entropy collector!");
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seed_noise();
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/****************************************
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** Initialize block device parameters **
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****************************************/
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{
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Block::Session::Operations ops;
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blk.info(&blk_total, &blk_size, &ops);
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if (!ops.supported(Block::Packet_descriptor::WRITE))
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die("block device not writeable!");
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}
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}
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~Main()
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{
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/* wipe noise state */
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seed_noise();
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jent_entropy_collector_free(jent);
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}
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void submit_noise(Block::Packet_descriptor const &pkt)
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{
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uint32_t *buffer = (uint32_t*)pkt_source.packet_content(pkt);
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for (size_t i = 0; i < ((pkt.block_count()*blk_size) / sizeof(uint32_t)); ++i)
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buffer[i] = pcg32_random_r(&pcg);
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pkt_source.submit_packet(pkt);
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}
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void shred()
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{
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float const mbytes = (float(blk_total) * float(blk_size)) / (1<<20);
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log("shredding ", mbytes/(1<<10), " GiB...");
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auto start_ms = timer.elapsed_ms();
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size_t const blk_per_pkt = PKT_SIZE / blk_size;
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size_t const bytes_per_pkt = blk_per_pkt * blk_size;
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/*
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* send two packets in succession, the first write
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* aligns those that follow with end of the device
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*/
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Block::sector_t blk_offset = blk_total % blk_per_pkt;
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if (blk_offset == 0)
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blk_offset = blk_per_pkt;
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{
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Block::Packet_descriptor pkt(
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pkt_source.alloc_packet(bytes_per_pkt),
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Block::Packet_descriptor::WRITE,
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0, blk_offset);
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submit_noise(pkt);
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}
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{
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Block::Packet_descriptor pkt(
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pkt_source.alloc_packet(bytes_per_pkt),
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Block::Packet_descriptor::WRITE,
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blk_offset, blk_per_pkt);
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submit_noise(pkt);
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blk_offset += blk_per_pkt;
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}
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while (true) {
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Block::Packet_descriptor const ack = pkt_source.get_acked_packet();
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if (!ack.succeeded())
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error("ack indicates failure ", ack.block_number(),"/",blk_total);
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pkt_source.release_packet(ack);
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if (blk_offset >= blk_total) break;
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/* reuse packet buffer region */
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Block::Packet_descriptor const pkt(
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ack, Block::Packet_descriptor::WRITE,
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blk_offset, blk_per_pkt);
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submit_noise(pkt);
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blk_offset += blk_per_pkt;
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}
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Block::Packet_descriptor const ack = pkt_source.get_acked_packet();
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if (!ack.succeeded())
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error("ack indicates failure ", ack.block_number(),"/",blk_total);
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float seconds = (timer.elapsed_ms() - start_ms) / 1000;
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log("shred complete, ", mbytes / seconds, " MiB/s");
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}
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/**
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* Verify a block, PCG must first be seeked into position
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*/
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bool verify_block(Block::sector_t sector)
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{
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Block::Packet_descriptor pkt(
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pkt_source.alloc_packet(blk_size),
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Block::Packet_descriptor::READ, sector, 1);
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pkt_source.submit_packet(pkt);
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pkt = pkt_source.get_acked_packet();
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pkt_source.release_packet(pkt);
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if (!pkt.succeeded())
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die("error while reading back sector ", sector);
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uint32_t *buffer = (uint32_t*)pkt_source.packet_content(pkt);
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for (size_t i = 0; i < (blk_size / sizeof(uint32_t)); ++i) {
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if (buffer[i] != pcg32_random_r(&pcg))
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die("sector ", sector, " is invalid");
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}
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return true;
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}
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/**
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* Verify random blocks
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*/
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void verify()
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{
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/* a weak RNG to generate skips */
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pcg32_random_t skip_gen;
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pcg32_srandom_r(&skip_gen, pcg32_random_r(&pcg), pcg32_random_r(&pcg));
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/* reset the noise generator */
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pcg32_srandom_r(&pcg, pcg_init[0], pcg_init[1]);
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/* make jumps of approximately 1 Mib */
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int const max_jump = (2<<20) / blk_size;
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int const step = blk_size / sizeof(uint32_t);
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Block::sector_t sector_offset = 0;
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unsigned long count = 0;
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/* verify the first block and loop */
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if (!verify_block(sector_offset)) return;
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++count;
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/* random jump loop */
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while (true) {
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/* make a bounded random jumps */
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Block::sector_t skip =
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pcg32_boundedrand_r(&skip_gen, max_jump)+1;
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if (sector_offset+skip >= blk_total)
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break;
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/* move the sector offset ahead */
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sector_offset += skip;
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/* seek the noise source ahead for the next read */
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pcg32_advance_r(&pcg, (skip-1)*step);
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if (!verify_block(sector_offset)) return;
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++count;
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}
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/* verify the last block */
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pcg32_advance_r(&pcg, (blk_total-(sector_offset+2))*step);
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if (!verify_block(blk_total-1)) return;
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++count;
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log(count, " blocks passed random spot check");
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}
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};
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void Component::construct(Genode::Env &env)
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{
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Blk_shred::Main main(env);
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main.shred();
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main.verify();
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env.parent().exit(0);
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}
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3
src/app/blk_shred/target.mk
Normal file
3
src/app/blk_shred/target.mk
Normal file
@@ -0,0 +1,3 @@
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TARGET = blk_shred
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LIBS = base jitterentropy libpcg_random
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SRC_CC = main.cc
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Reference in New Issue
Block a user