plasma-framework/remote/signing.cpp

/*
 *  Copyright (C) 2010 by Diego '[Po]lentino' Casella <polentino911@gmail.com>
 *
 *  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 of the License, 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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software Foundation
 *  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */


#include "signing.h"
#include "signing_p.h"

#include <gpgme.h>
#include <gpgme++/gpgmefw.h>
#include <gpgme++/global.h>
#include <gpgme++/context.h>
#include <gpgme++/error.h>
#include <gpgme++/engineinfo.h>
#include <gpgme++/key.h>
#include <gpgme++/keylistresult.h>
#include <gpgme++/keygenerationresult.h>
#include <gpgme++/importresult.h>
#include <gpgme++/data.h>

#include <QtCore/QDir>
#include <QtCore/QStringList>

#include <kdirwatch.h>
#include <kdebug.h>
#include <kstandarddirs.h>
#include <kuser.h>

#include "plasma/package.h"

#include <cstdio> // FILE

namespace Plasma
{

SigningPrivate::SigningPrivate(Signing *auth, const QString &path)
        : q(auth),
          m_keystorePath(path)
{
    GpgME::initializeLibrary();
    GpgME::Error error = GpgME::checkEngine(GpgME::OpenPGP);
    if (error) {
#ifndef NDEBUG
        kDebug() << "OpenPGP engine not found: authentication will not work.";
#endif
        return;
    }

    m_gpgContext = GpgME::Context::createForProtocol(GpgME::OpenPGP);
    m_gpgContext->setKeyListMode(GPGME_KEYLIST_MODE_LOCAL | GPGME_KEYLIST_MODE_SIGS);

    m_keystorePath = path;

    if (m_keystorePath.isEmpty()) {
        // From the gpgme doc: if the homeDirectory() is null, it means we are using the standard dir,
        // that is "/home/$USER/.gnupg/ ; so let's retrieve it.
        KUser user;
        m_keystorePath.append(user.homeDir()).append("/.gnupg/");
    } else {
        error = m_gpgContext->setEngineHomeDirectory(m_keystorePath.toLatin1().data());
        if (error) {
#ifndef NDEBUG
            kDebug() << "Failed setting custom gpg keystore directory: using default.";
#endif
        }
    }

    m_keystoreDir = new KDirWatch();
    m_keystoreDir->addDir(m_keystorePath);
    m_keystoreDir->addDir(ultimateKeyStoragePath());
    m_keystoreDir->startScan(true);

    // Start watching the keystore and the dir with the kde keys, and notify for changed
    q->connect(m_keystoreDir, SIGNAL(created(const QString &)), q, SLOT(processKeystore(const QString &)));
    q->connect(m_keystoreDir, SIGNAL(dirty(const QString &)), q, SLOT(keyAdded(const QString &)));
    q->connect(m_keystoreDir, SIGNAL(deleted(const QString &)), q, SLOT(keyRemoved(const QString &)));
}

SigningPrivate::~SigningPrivate()
{
    delete m_keystoreDir;
}

QString SigningPrivate::ultimateKeyStoragePath() const
{
    return KStandardDirs::installPath("data") + "plasmakeys/";
}

void SigningPrivate::registerUltimateTrustKeys()
{
    QSet<QByteArray> tmp;
    keys[UltimatelyTrusted] = tmp;

    if (!m_gpgContext) {
#ifndef NDEBUG
        kDebug() << "GPGME context not valid: please re-initialize the library.";
#endif
        return;
    }

    QString path = ultimateKeyStoragePath();
    QDir dir(path);
    if (!dir.exists() || path.isEmpty()) {
#ifndef NDEBUG
        kDebug() << "Directory with KDE keys not found: aborting";
#endif
        return;
    }

    const QStringList keyFiles = dir.entryList(QDir::Files); // QDir::Files is rendundant in this stage

    // Foreach file found, open it and import the key into the gpg keyring.
    // First avoid firing multiple entryWritten() signals
    m_keystoreDir->stopScan();

    foreach (QString keyFile, keyFiles) {
        FILE *fp;
        fp = fopen(keyFile.toLatin1().data(), "r");
        GpgME::Data data(fp);
        GpgME::ImportResult iRes = m_gpgContext->importKeys(data);
        if (iRes.error()) {
#ifndef NDEBUG
            kDebug() << "Error while importing the key located at: " << keyFile;
#endif
#ifndef NDEBUG
            kDebug() << " The error is:" << iRes.error().asString() << "; Skipping.";
#endif
            continue;
        }

        // The first fingerprint listed is the one we need to save
        tmp.insert(iRes.import(0).fingerprint());
    }
    keys[UltimatelyTrusted] = tmp;

    // Restore scanning folders
    m_keystoreDir->startScan(true, true);
}

void SigningPrivate::splitKeysByTrustLevel()
{
    if (!m_gpgContext) {
#ifndef NDEBUG
        kDebug() << "GPGME context not valid: please re-initialize the library.";
#endif
        return;
    }

    QSet<QByteArray> temp = keys[UltimatelyTrusted];
    keys.clear();
    keys[UltimatelyTrusted] = temp;

    // Splitting the keys by their trust level is a boring task, since we have to distinguish
    // `which key has been signed with an other given key` :P
    //
    // Loop 1: import and load the KDE keys, already done in registerUltimateTrustKeys()
    //
    // Loop 2: load the user keyring (private keys only), and loop for:
    //    - a: a key not yet expired;
    //    - b: a key not already present in the keys[UltimatelyTrusted];
    //
    // Loop 3: load the user keyring, and loop for:
    //    - a: a key not yet expired;
    //    - b: a key not already present in the keys[UltimatelyTrusted];
    //    - c: a key not yet in keys[SelfTrusted]
    //
    // After Loop 3, the tmp object contains the remaining keys not yet processed.
    //
    // Loop 4: foreach key not yet classified, inspect their signatures and:
    //    - a: if contains a key from keys[UltimatelyTrusted], save it in keys[FullyTrusted];
    //    - b: if contains a key from keys[SelfTrusted], save it in keys[UserTrusted];
    //    - c: if the signature is unknown, let's save it in keys[UnknownTrusted].
    QSet<QByteArray> tmp;

    GpgME::Error error = m_gpgContext->startKeyListing("", true);
    while (!error) { // Loop 2
        GpgME::Key key = m_gpgContext->nextKey(error);
        if (error) {
            break;
        }

        QByteArray data(key.subkey(0).fingerprint());

        // If the key is disabled, expired, invalid or revoked, put it in the untrusted list
        if (key.isDisabled() || key.isExpired() || key.isInvalid() || key.isRevoked()) {
            keys[CompletelyUntrusted].insert(data);
        } else if (!keys[UltimatelyTrusted].contains(data)) {
            // Ensure we are not processing twice the trusted KDE keys
            // The keys is new, valid and private: save it !
            keys[SelfTrusted].insert(data);
        }
    }
    GpgME::KeyListResult lRes = m_gpgContext->endKeyListing();
}

Plasma::TrustLevel SigningPrivate::addKeyToCache(const QByteArray &fingerprint)
{
    if (!m_gpgContext) {
#ifndef NDEBUG
        kDebug() << "GPGME context not valid: please re-initialize the library.";
#endif
        return UnknownTrusted;
    }

    GpgME::Error error;
    GpgME::Key key = m_gpgContext->key(fingerprint.data(), error);
    if (error) {
        keys[UnknownTrusted].insert(fingerprint);
        return UnknownTrusted;
    }

    if (keys[UltimatelyTrusted].contains(fingerprint)) {
        return UltimatelyTrusted;
    } else if (keys[SelfTrusted].contains(fingerprint)) {
        return SelfTrusted;
    }

    // If the key is disabled, expired, invalid or revoked, put it in the untrusted list
    if (key.isDisabled() || key.isExpired() || key.isInvalid() || key.isRevoked()) {
        keys[CompletelyUntrusted].insert(fingerprint);
        return CompletelyUntrusted;
    }

    for (unsigned int i = 0; i < key.numUserIDs(); ++i) {
        foreach (const GpgME::UserID::Signature &signature, key.userID(i).signatures()) {
            if (keys[UltimatelyTrusted].contains(signature.signerKeyID())) {
                // if the unknown key has a signer that is a kde key, let's trust it
                keys[FullyTrusted].insert(fingerprint);
                return FullyTrusted;
            } else if (keys[SelfTrusted].contains(signature.signerKeyID())) {
                // if the unknown key has a signer that is a user key, let's trust it
                keys[UserTrusted].insert(fingerprint);
                return UserTrusted;
            }
        }
    }

    // We didn't stored the unknown key in the previous loop, which means that we
    // don't know the hey al all.
    keys[UnknownTrusted].insert(fingerprint);
    return UnknownTrusted;
}

#ifndef NDEBUG
void SigningPrivate::dumpKeysToDebug()
{
    kDebug() << "UltimatelyTrusted = " << keys[UltimatelyTrusted];
    kDebug() << "FullyTrusted = " << keys[FullyTrusted];
    kDebug() << "SelfTrusted = " << keys[SelfTrusted];
    kDebug() << "UserTrusted = " << keys[UserTrusted];
    kDebug() << "UnknownTrusted = " << keys[UnknownTrusted];
    kDebug() << "CompletelyUntrusted = " << keys[CompletelyUntrusted];
}
#endif

QStringList SigningPrivate::keysID(const bool returnPrivate) const
{
    QStringList result;

    if (!m_gpgContext) {
#ifndef NDEBUG
        kDebug() << "GPGME context not valid: please re-initialize the library.";
#endif
        return result;
    }

    GpgME::Error error = m_gpgContext->startKeyListing("", returnPrivate);
    while (!error) {
        GpgME::Key k = m_gpgContext->nextKey(error);
        if (error) {
            break;
        }

        result.append(k.subkey(0).fingerprint());
    }
    GpgME::KeyListResult lRes = m_gpgContext->endKeyListing();
    if (lRes.error()) {
#ifndef NDEBUG
        kDebug() << "Error while ending the keyListing operation: " << lRes.error().asString();
#endif
    }

    return result;
}

void SigningPrivate::processKeystore(const QString &path)
{
    if (path != m_keystorePath) {
        registerUltimateTrustKeys();
        return;
    }

    QSet<QByteArray> oldValues;
    oldValues += keys[UnverifiableTrust];
    oldValues += keys[CompletelyUntrusted];
    oldValues += keys[UnknownTrusted];
    oldValues += keys[SelfTrusted];
    oldValues += keys[FullyTrusted];
    oldValues += keys[UltimatelyTrusted];

    splitKeysByTrustLevel();

    QSet<QByteArray> newValues;
    newValues += keys[UnverifiableTrust];
    newValues += keys[CompletelyUntrusted];
    newValues += keys[UnknownTrusted];
    newValues += keys[SelfTrusted];
    newValues += keys[FullyTrusted];
    newValues += keys[UltimatelyTrusted];

    QString result;
    bool keystoreIncreased = (newValues.size() >= oldValues.size());
    if (keystoreIncreased) {
        foreach (QByteArray value, newValues) {
            if (!oldValues.contains(value)) {
                // Found the key added
                result.append(value);
                break;
            }
        }
    } else {
        foreach (QByteArray value, oldValues) {
            if (!newValues.contains(value)) {
                // Found the removed key
                result.append(value);
                break;
            }
        }
    }

    if (!result.isEmpty()) {
        if (keystoreIncreased) {
            emit q->keyAdded(result);
        } else {
            emit q->keyRemoved(result);
        }
    }
}

void SigningPrivate::keyAdded(const QString &path)
{
    if (path == m_keystorePath) {
        // we don't worry about keys added to the key store path,
        // just the ultimate store dir
        return;
    }

    // Avoid firing multiple signals by kdirwatch instances
    m_keystoreDir->stopScan();

    FILE *fp;
    fp = fopen(path.toLatin1().data(), "r");
    GpgME::Data data(fp);
    GpgME::ImportResult iRes = m_gpgContext->importKeys(data);

    bool alreadyInMap = false;

    // Ensure we don't already have the key
    foreach (QByteArray sec, keys[UltimatelyTrusted]) {
        if (strcmp(sec.data(), iRes.import(0).fingerprint())) {
            alreadyInMap = true;
            break;
        }
    }

    if (!alreadyInMap) {
        keys[UltimatelyTrusted] << QByteArray(iRes.import(0).fingerprint());
        splitKeysByTrustLevel();
    }

    // Restore scanning folders
    m_keystoreDir->startScan(true, true);

    QString result(iRes.import(0).fingerprint());
    emit(q->keyAdded(result));
}

void SigningPrivate::keyRemoved(const QString &path)
{
    // Avoid firing multiple signals by kdirwatch instances
    m_keystoreDir->stopScan();

    if (path == m_keystorePath) {
        // Restore scanning folders
        m_keystoreDir->startScan(true, true);
        return;
    }

    QSet<QByteArray> oldKeys = keys[UltimatelyTrusted];
    registerUltimateTrustKeys();
    QSet<QByteArray> newkeys = keys[UltimatelyTrusted];

    QString result;
    foreach (QByteArray key, oldKeys) {
        if (!newkeys.contains(key)) {
            // We found the missing key :)
            result.append(key);
            break;
        }
    }


    GpgME::Error error = m_gpgContext->startKeyListing("");
    while (!error) {
        GpgME::Key k = m_gpgContext->nextKey(error);
        if (error) {
            break;
        }

        if (result.contains(k.subkey(0).fingerprint())) {
            error = m_gpgContext->startKeyDeletion(k, true); // GG

            if (error) {
#ifndef NDEBUG
                kDebug() << "Can't delete key with fingerprint: " << result;
#endif
                m_gpgContext->endKeyListing();
                return;
            }

            break;
        }
    }
    GpgME::KeyListResult lRes = m_gpgContext->endKeyListing();
    if (lRes.error()) {
#ifndef NDEBUG
        kDebug() << "Error while ending the keyListing operation: " << lRes.error().asString();
#endif
    }

    splitKeysByTrustLevel();

    // Restore scanning folders
    m_keystoreDir->startScan(true, true);

    emit(q->keyRemoved(result));
}

QStringList SigningPrivate::signersOf(const QString id) const
{
    QStringList result;
    GpgME::Error error;
    GpgME::Key key = m_gpgContext->key(id.toLatin1().data(), error);

    if (!error) {
        for (unsigned int i = 0; i < key.numUserIDs(); ++i) {
            foreach (const GpgME::UserID::Signature &signature, key.userID(i).signatures()) {
                QString sig(signature.signerKeyID());
                if (!result.contains(sig) && id != sig) {
                    result.append(sig);
                }
            }
        }
    }

    //kDebug() << "Hey, the key " << id << " has been signed with " << result;

    return result;
}

Signing::Signing(const QString &keystorePath)
        : QObject(),
        d(new SigningPrivate(this, keystorePath))
{
    d->registerUltimateTrustKeys();
    d->splitKeysByTrustLevel();
}

Signing::~Signing()
{
    delete d;
}

QStringList Signing::keysByTrustLevel(TrustLevel trustLevel) const
{
    if (trustLevel == UnverifiableTrust) {
        return QStringList();
    }

    QSet<QByteArray> s = d->keys[trustLevel];
    QStringList tmp;
    foreach (const QByteArray &sa, s) {
        tmp.append(sa);
    }

    return tmp;
}

TrustLevel Signing::trustLevelOf(const QString &keyID) const
{
    if (keyID.isEmpty()) {
        return Plasma::UnverifiableTrust;
    }

    for (int i = (int)Plasma::UnverifiableTrust; i <= (int)Plasma::UltimatelyTrusted; ++i) {
        QSet<QByteArray> tmp = d->keys[(Plasma::TrustLevel)i];
        foreach (QByteArray key, tmp) {
            if (key.contains(keyID.toLatin1().data())) {
                return (Plasma::TrustLevel)i;
            }
        }
    }

    return d->addKeyToCache(keyID.toLatin1());
}

QString Signing::signerOf(const Package &package) const
{
    const QString contents = package.path() + "contents.hash";

    if (!QFile::exists(contents)) {
#ifndef NDEBUG
        kDebug() << "not contents hash for package at" << package.path();
#endif
        return QString();
    }

    QFile file(contents);

    if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) {
#ifndef NDEBUG
        kDebug() << "could not open contents.hash file for reading" << contents;
#endif
        return QString();
    }

    const QByteArray hash = file.read(10 * 1024);
    const QString actualHash = package.contentsHash();
    if (actualHash != hash) {
#ifndef NDEBUG
        kDebug() << "contents.hash does not match contents of package" << package.path();
#endif
        return QString();
    }

    return d->verifySignature(contents, QString());
}

QString Signing::signerOf(const QUrl &package, const QUrl &signature) const
{
#ifndef NDEBUG
    kDebug() << "Checking existence of " << package;
#endif
#ifndef NDEBUG
    kDebug() << "Checking existence of " << signature;
#endif

    if (!package.isLocalFile() || (!signature.isEmpty() && !signature.isLocalFile())) {
#ifndef NDEBUG
        kDebug() << "Remote urls not yet supported. FIXME.";
#endif
        return QString();
    }

    return d->verifySignature(package.path(), signature.path());
}

QString SigningPrivate::verifySignature(const QString &filePath, const QString &signature)
{
    if (!QFile::exists(filePath)) {
#ifndef NDEBUG
        kDebug() << "Package" << filePath << "does not exist: signature verification aborted.";
#endif
        return QString();
    }

    const QString signaturePath = signature.isEmpty() ? filePath + (".sig") : signature;

    if (!QFile::exists(signaturePath)) {
#ifndef NDEBUG
        kDebug() << "Signature" << signaturePath << "does not exist: signature verification aborted.";
#endif
        return QString();
    }

    //kDebug() << "Cheking if " << filePath << " and " << signaturePath << " matches";

    FILE *pFile = fopen(filePath.toLocal8Bit().data(), "r");
    if (!pFile) {
#ifndef NDEBUG
        kDebug() << "failed to open file" << filePath;
#endif
        return QString();
    }

    FILE *pSig = fopen(signaturePath.toLocal8Bit().data(), "r");
    if (!pSig) {
#ifndef NDEBUG
        kDebug() << "failed to open package file" << signaturePath;
#endif
        fclose(pFile);
        return QString();
    }

    GpgME::Data file(pFile);
    GpgME::Data sig(pSig);

    GpgME::VerificationResult vRes = m_gpgContext->verifyDetachedSignature(sig, file);
    QString rv;

    if (!vRes.error()) {
        //kDebug() << "got" << vRes.signatures().size() << "signatures out" << vRes.error().asString();
        foreach (GpgME::Signature sig, vRes.signatures()) {
            if (sig.fingerprint()) {
                rv = sig.fingerprint();
                break;
            }
        }

        //kDebug() << "message " << filePath << " and signature " << signaturePath << "matched! The fingerprint of the signer is: " << rv;
    }

    fclose(pFile);
    fclose(pSig);
    return rv;
}

QString Signing::keyStorePath() const
{
    return d->m_keystorePath;
}

QString Signing::descriptiveString(const QString &keyID) const
{
    if (keyID.isEmpty()) {
        return QString();
    }

    if (!d->m_gpgContext) {
#ifndef NDEBUG
        kDebug() << "GPGME context not valid: please re-initialize the library.";
#endif
        return QString();
    }

    GpgME::Error error;
    GpgME::Key key = d->m_gpgContext->key(keyID.toLatin1().data(), error);
    if (error) {
        return QString();
    }

    return key.userID(0).id();
}

}

#include "moc_signing.cpp"