#!/bin/bash

# SPDX-License-Identifier: GPL-2.0

#

# evmctl {,ima_}{sign,verify} tests

#

# Copyright (C) 2020 Vitaly Chikunov <vt@altlinux.org>

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2, or (at your option)

# any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

cd "$(dirname "$0")" || exit 1

PATH=../src:$PATH

source ./functions.sh

_require cmp evmctl getfattr openssl xxd

if cmp -b 2>&1 | grep -q "invalid option"; then

	echo "cmp does not support -b (cmp from busybox?) Use cmp from diffutils"

	exit "$HARDFAIL"

fi

./gen-keys.sh >/dev/null 2>&1

trap _report_exit EXIT

set -f # disable globbing

# Determine keyid from a cert

_keyid_from_cert() {

  local cer=${1%.*}.cer cmd

  local tmp

  cer=test-${cer#test-}

  # shellcheck disable=SC2086

  cmd="openssl x509 $OPENSSL_ENGINE \

          -in $cer -inform DER -pubkey -noout"

  id=$($cmd 2>/dev/null \

    | openssl asn1parse \

    | grep BIT.STRING \

    | cut -d: -f1)

  if [ -z "$id" ]; then

    echo - "$cmd" >&2

    echo "Cannot asn1parse $cer to determine keyid" >&2

    exit 1

  fi

  tmp=$(mktemp)

  # shellcheck disable=SC2086

  openssl x509 $OPENSSL_ENGINE \

      -in "$cer" -inform DER -pubkey -noout 2>/dev/null \

    | openssl asn1parse -strparse "$id" -out "$tmp" -noout

  # shellcheck disable=SC2002

  cat "$tmp" \

    | openssl dgst -c -sha1 \

    | cut -d' ' -f2 \

    | grep -o ":..:..:..:..$" \

    | tr -d :

  rm -f "$tmp"

}

# Convert test $type into evmctl op prefix

_op() {

  if [ "$1" = ima ]; then

    echo ima_

  fi

}

# Convert test $type into xattr name

_xattr() {

  if [ "$1" = ima ]; then

    echo user.ima

  else

    echo user.evm

  fi

}

# Check that detached signature matches xattr signature

_test_sigfile() {

  local file=$1 attr=$2 file_sig=$3 file_sig2=$4

  if [ ! -e "$file_sig" ]; then

    color_red

    echo "evmctl ima_sign: no detached signature $file_sig"

    color_restore

    rm "$file"

    return "$FAIL"

  fi

  _extract_xattr "$file" "$attr" "$file_sig2"

  if ! cmp -bl "$file_sig" "$file_sig2"; then

    color_red

    echo "evmctl ima_sign: xattr signature on $file differ from detached $file_sig"

    color_restore

    rm "$file" "$file_sig" "$file_sig2"

    return "$FAIL"

  fi

  # Leave '$file_sig' for ima_verify --sigfile test.

  rm "$file_sig2"

}

# Run single sign command

_evmctl_sign() {

  local type=$1 key=$2 alg=$3 file=$4 opts=$5

  # Can check --sigfile for ima_sign

  [ "$type" = ima ] && opts+=" --sigfile"

  # shellcheck disable=SC2086

  ADD_TEXT_FOR="$alg ($key)" ADD_DEL=$file \

    _evmctl_run "$(_op "$type")sign" $opts \

    --hashalgo "$alg" --key "$key" --xattr-user "$file" || return

  if [ "$type" = ima ]; then

    _test_sigfile "$file" "$(_xattr "$type")" "$file.sig" "$file.sig2"

  fi

}

# Run and test {ima_,}sign operation

check_sign() {

  # Arguments are passed via global vars:

  # TYPE (ima or evm),

  # KEY,

  # ALG (hash algo),

  # PREFIX (signature header prefix in hex),

  # OPTS (additional options for evmctl),

  # FILE (working file to sign).

  local "$@"

  local KEY=${KEY%.*}.key

  local FILE=${FILE:-$ALG.txt}

  # Normalize key filename

  KEY=test-${KEY#test-}

  # Append suffix to files for negative tests, because we may

  # leave only good files for verify tests.

  _test_expected_to_fail && FILE+='~'

  rm -f $FILE

  if ! touch $FILE; then

    color_red

    echo "Can't create test file: $FILE"

    color_restore

    return "$HARDFAIL"

  fi

  if _test_expected_to_pass; then

    # Can openssl work with this digest?

    cmd="openssl dgst $OPENSSL_ENGINE -$ALG $FILE"

    echo - "$cmd"

    if ! $cmd >/dev/null; then

      echo "${CYAN}$ALG ($KEY) test is skipped (openssl is unable to digest)$NORM"

      return "$SKIP"

    fi

    if [ ! -e "$KEY" ]; then

      echo "${CYAN}$ALG ($KEY) test is skipped (key file not found)$NORM"

      return "$SKIP"

    fi

    # Can openssl sign with this digest and key?

    cmd="openssl dgst $OPENSSL_ENGINE -$ALG -sign $KEY -hex $FILE"

    echo - "$cmd"

    if ! $cmd >/dev/null; then

      echo "${CYAN}$ALG ($KEY) test is skipped (openssl is unable to sign)$NORM"

      return "$SKIP"

    fi

  fi

  # Insert keyid from cert into PREFIX in-place of marker `:K:'

  if [[ $PREFIX =~ :K: ]]; then

    keyid=$(_keyid_from_cert "$KEY")

    if [ $? -ne 0 ]; then

      color_red

      echo "Unable to determine keyid for $KEY"

      color_restore

      return "$HARDFAIL"

    fi

    [ "$VERBOSE" -gt 2 ] && echo "  Expected keyid: $keyid"

    PREFIX=${PREFIX/:K:/$keyid}

  fi

  # Perform signing by evmctl

  _evmctl_sign "$TYPE" "$KEY" "$ALG" "$FILE" "$OPTS" || return

  # First simple pattern match the signature.

  ADD_TEXT_FOR=$ALG \

    _test_xattr "$FILE" "$(_xattr "$TYPE")" "$PREFIX.*" || return

  # This is all we can do for v1 signatures.

  [[ "$OPTS" =~ --rsa ]] && return "$OK"

  # This is all we can do for evm.

  [[ "$TYPE" =~ evm ]] && return "$OK"

  # Extract signature to a file

  _extract_xattr "$FILE" "$(_xattr "$TYPE")" "$FILE.sig2" "$PREFIX"

  # Verify extracted signature with openssl

  cmd="openssl dgst $OPENSSL_ENGINE -$ALG -verify ${KEY%.*}.pub \

	-signature $FILE.sig2 $FILE"

  echo - "$cmd"

  if ! $cmd; then

    color_red_on_failure

    echo "Signature v2 verification with openssl is failed."

    color_restore

    rm "$FILE.sig2"

    return "$FAIL"

  fi

  rm "$FILE.sig2"

  return "$OK"

}

# Test verify operation

check_verify() {

  # Arguments are passed via global vars:

  # TYPE (ima or evm),

  # KEY,

  # ALG (hash algo),

  # OPTS (additional options for evmctl),

  # FILE (filename to verify).

  local "$@"

  # shellcheck disable=SC2086

  if ! openssl dgst $OPENSSL_ENGINE -"$ALG" /dev/null >/dev/null 2>&1; then

    echo $CYAN"$ALG ($KEY) test is skipped (openssl does not support $ALG)"$NORM

    return $SKIP

  fi

  # shellcheck disable=SC2086

  ADD_TEXT_FOR="$FILE ($KEY)" \

    _evmctl_run "$(_op "$TYPE")verify" --key "$KEY" --xattr-user $OPTS "$FILE"

}

# Test runners

# Perform sign and verify ima and evm testing

sign_verify() {

  local key=$1 alg=$2 prefix="$3" opts="$4"

  local file=$alg.txt

  # Set defaults:

  # Public key is different for v1 and v2 (where x509 cert is used).

  if [[ $opts =~ --rsa ]]; then

    KEY=test-$key.pub

  else

    KEY=test-$key.cer

  fi

  ALG=$alg

  PREFIX=$prefix

  OPTS=$opts

  FILE=$file

  TYPE=ima

  if expect_pass check_sign; then

    # Normal verify with proper key should pass

    expect_pass check_verify

    expect_pass check_verify OPTS="--sigfile"

    # Multiple files and some don't verify

    expect_fail check_verify FILE="/dev/null $file"

    rm "$FILE.sig"

  fi

  TYPE=evm

  # Avoid running blkid for evm tests which may require root

  # No generation on overlayfs:

  # ioctl(3, FS_IOC_GETVERSION, 0x7ffd8e0bd628) = -1 ENOTTY (Inappropriate ioctl for device)

  OPTS="$opts --uuid --generation 0"

  if expect_pass check_sign; then

    # Normal verify with proper key

    expect_pass check_verify

    # Verify with wrong key

    expect_fail check_verify KEY=rsa2048

  fi

  # Note: Leaving TYPE=evm and file is evm signed

}

# Test --keys

try_different_keys() {

  # This run after sign_verify which leaves

  # TYPE=evm and file is evm signed

  # v2 signing can work with multiple keys in --key option

  if [[ ! $OPTS =~ --rsa ]]; then

    # Have correct key in the key list

    expect_pass check_verify KEY="test-rsa2048.cer,$KEY"

    expect_pass check_verify KEY="/dev/null,$KEY,"

  fi

  # Try key that is not used for signing

  expect_fail check_verify KEY=rsa2048

  # Try completely wrong key files

  expect_fail check_verify KEY=/dev/null

  expect_fail check_verify KEY=/dev/zero

}

try_different_sigs() {

  # TYPE=evm and file is evm signed

  # Test --imasig

  if expect_pass check_sign OPTS="$OPTS --imasig"; then

    # Verify both evm and ima sigs

    expect_pass check_verify

    expect_pass check_verify TYPE=ima

  fi

  # Test --imahash

  if expect_pass check_sign OPTS="$OPTS --imahash"; then

    expect_pass check_verify

    # IMA hash is not verifiable by ima_verify

    expect_fail check_verify TYPE=ima

  fi

  # Test --portable

  expect_pass check_sign OPTS="$OPTS --portable" PREFIX=0x05

  # Cannot be verified for now, until that support is added to evmctl

  # Test -i (immutable)

  expect_pass check_sign OPTS="$OPTS -i" PREFIX=0x0303

  # Cannot be verified for now

}

# Single test args: type key hash signature-prefix "evmctl-options"

# sign_verify args:      key hash signature-prefix "evmctl-options"

# Only single test can be prefixed with expect_{fail,pass}

# `sign_verify' can not be prefixed with expect_{fail,pass} because

# it runs multiple tests inside. See more tests there.

# signature-prefix can contain `:K:' which will be resolved to keyid (v2 only)

## Test v1 signatures

# Signature v1 only supports sha1 and sha256 so any other should fail

expect_fail \

  check_sign TYPE=ima KEY=rsa1024 ALG=md5 PREFIX=0x0301 OPTS=--rsa

sign_verify  rsa1024  sha1    0x0301 --rsa

sign_verify  rsa1024  sha256  0x0301 --rsa

  try_different_keys

  try_different_sigs

## Test v2 signatures with RSA PKCS#1

# List of allowed hashes much greater but not all are supported.

sign_verify  rsa1024  md5     0x030201:K:0080

sign_verify  rsa1024  sha1    0x030202:K:0080

sign_verify  rsa1024  sha224  0x030207:K:0080

sign_verify  rsa1024  sha256  0x030204:K:0080

  try_different_keys

  try_different_sigs

sign_verify  rsa1024  sha384  0x030205:K:0080

sign_verify  rsa1024  sha512  0x030206:K:0080

sign_verify  rsa1024  rmd160  0x030203:K:0080

# Test v2 signatures with EC-RDSA

_enable_gost_engine

sign_verify  gost2012_256-A md_gost12_256 0x030212:K:0040

sign_verify  gost2012_256-B md_gost12_256 0x030212:K:0040

sign_verify  gost2012_256-C md_gost12_256 0x030212:K:0040

sign_verify  gost2012_512-A md_gost12_512 0x030213:K:0080

sign_verify  gost2012_512-B md_gost12_512 0x030213:K:0080

# Test if signing with wrong key length does not work.

expect_fail \

  check_sign TYPE=ima KEY=gost2012_512-B ALG=md_gost12_256 PREFIX=0x0302 OPTS=

expect_fail \

  check_sign TYPE=ima KEY=gost2012_256-B ALG=md_gost12_512 PREFIX=0x0302 OPTS=