nix/src/libstore/restricted-store.cc

#include "nix/store/restricted-store.hh"
#include "nix/store/build-result.hh"
#include "nix/util/callback.hh"
#include "nix/store/realisation.hh"
#include "nix/store/local-store.hh"

namespace nix {

static StorePath pathPartOfReq(const SingleDerivedPath & req)
{
    return std::visit(
        overloaded{
            [&](const SingleDerivedPath::Opaque & bo) { return bo.path; },
            [&](const SingleDerivedPath::Built & bfd) { return pathPartOfReq(*bfd.drvPath); },
        },
        req.raw());
}

static StorePath pathPartOfReq(const DerivedPath & req)
{
    return std::visit(
        overloaded{
            [&](const DerivedPath::Opaque & bo) { return bo.path; },
            [&](const DerivedPath::Built & bfd) { return pathPartOfReq(*bfd.drvPath); },
        },
        req.raw());
}

bool RestrictionContext::isAllowed(const DerivedPath & req)
{
    return isAllowed(pathPartOfReq(req));
}

/**
 * A wrapper around LocalStore that only allows building/querying of
 * paths that are in the input closures of the build or were added via
 * recursive Nix calls.
 */
struct RestrictedStore : public virtual IndirectRootStore, public virtual GcStore
{
    ref<const LocalStore::Config> config;

    ref<LocalStore> next;

    RestrictionContext & goal;

    RestrictedStore(ref<LocalStore::Config> config, ref<LocalStore> next, RestrictionContext & goal)
        : Store{*config}
        , LocalFSStore{*config}
        , config{config}
        , next(next)
        , goal(goal)
    {
    }

    Path getRealStoreDir() override
    {
        return next->config->realStoreDir;
    }

    StorePathSet queryAllValidPaths() override;

    void queryPathInfoUncached(
        const StorePath & path, Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept override;

    void queryReferrers(const StorePath & path, StorePathSet & referrers) override;

    std::map<std::string, std::optional<StorePath>>
    queryPartialDerivationOutputMap(const StorePath & path, Store * evalStore = nullptr) override;

    std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
    {
        throw Error("queryPathFromHashPart");
    }

    StorePath addToStore(
        std::string_view name,
        const SourcePath & srcPath,
        ContentAddressMethod method,
        HashAlgorithm hashAlgo,
        const StorePathSet & references,
        PathFilter & filter,
        RepairFlag repair) override
    {
        throw Error("addToStore");
    }

    void addToStore(
        const ValidPathInfo & info,
        Source & narSource,
        RepairFlag repair = NoRepair,
        CheckSigsFlag checkSigs = CheckSigs) override;

    StorePath addToStoreFromDump(
        Source & dump,
        std::string_view name,
        FileSerialisationMethod dumpMethod,
        ContentAddressMethod hashMethod,
        HashAlgorithm hashAlgo,
        const StorePathSet & references,
        RepairFlag repair) override;

    void narFromPath(const StorePath & path, Sink & sink) override;

    void ensurePath(const StorePath & path) override;

    void registerDrvOutput(const Realisation & info) override;

    void queryRealisationUncached(
        const DrvOutput & id, Callback<std::shared_ptr<const Realisation>> callback) noexcept override;

    void
    buildPaths(const std::vector<DerivedPath> & paths, BuildMode buildMode, std::shared_ptr<Store> evalStore) override;

    std::vector<KeyedBuildResult> buildPathsWithResults(
        const std::vector<DerivedPath> & paths,
        BuildMode buildMode = bmNormal,
        std::shared_ptr<Store> evalStore = nullptr) override;

    BuildResult
    buildDerivation(const StorePath & drvPath, const BasicDerivation & drv, BuildMode buildMode = bmNormal) override
    {
        unsupported("buildDerivation");
    }

    void addTempRoot(const StorePath & path) override {}

    void addIndirectRoot(const Path & path) override {}

    Roots findRoots(bool censor) override
    {
        return Roots();
    }

    void collectGarbage(const GCOptions & options, GCResults & results) override {}

    void addSignatures(const StorePath & storePath, const StringSet & sigs) override
    {
        unsupported("addSignatures");
    }

    MissingPaths queryMissing(const std::vector<DerivedPath> & targets) override;

    virtual std::optional<std::string> getBuildLogExact(const StorePath & path) override
    {
        return std::nullopt;
    }

    virtual void addBuildLog(const StorePath & path, std::string_view log) override
    {
        unsupported("addBuildLog");
    }

    std::optional<TrustedFlag> isTrustedClient() override
    {
        return NotTrusted;
    }
};

ref<Store> makeRestrictedStore(ref<LocalStore::Config> config, ref<LocalStore> next, RestrictionContext & context)
{
    return make_ref<RestrictedStore>(config, next, context);
}

StorePathSet RestrictedStore::queryAllValidPaths()
{
    StorePathSet paths;
    for (auto & p : goal.originalPaths())
        paths.insert(p);
    for (auto & p : goal.addedPaths)
        paths.insert(p);
    return paths;
}

void RestrictedStore::queryPathInfoUncached(
    const StorePath & path, Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept
{
    if (goal.isAllowed(path)) {
        try {
            /* Censor impure information. */
            auto info = std::make_shared<ValidPathInfo>(*next->queryPathInfo(path));
            info->deriver.reset();
            info->registrationTime = 0;
            info->ultimate = false;
            info->sigs.clear();
            callback(info);
        } catch (InvalidPath &) {
            callback(nullptr);
        }
    } else
        callback(nullptr);
};

void RestrictedStore::queryReferrers(const StorePath & path, StorePathSet & referrers) {}

std::map<std::string, std::optional<StorePath>>
RestrictedStore::queryPartialDerivationOutputMap(const StorePath & path, Store * evalStore)
{
    if (!goal.isAllowed(path))
        throw InvalidPath("cannot query output map for unknown path '%s' in recursive Nix", printStorePath(path));
    return next->queryPartialDerivationOutputMap(path, evalStore);
}

void RestrictedStore::addToStore(
    const ValidPathInfo & info, Source & narSource, RepairFlag repair, CheckSigsFlag checkSigs)
{
    next->addToStore(info, narSource, repair, checkSigs);
    goal.addDependency(info.path);
}

StorePath RestrictedStore::addToStoreFromDump(
    Source & dump,
    std::string_view name,
    FileSerialisationMethod dumpMethod,
    ContentAddressMethod hashMethod,
    HashAlgorithm hashAlgo,
    const StorePathSet & references,
    RepairFlag repair)
{
    auto path = next->addToStoreFromDump(dump, name, dumpMethod, hashMethod, hashAlgo, references, repair);
    goal.addDependency(path);
    return path;
}

void RestrictedStore::narFromPath(const StorePath & path, Sink & sink)
{
    if (!goal.isAllowed(path))
        throw InvalidPath("cannot dump unknown path '%s' in recursive Nix", printStorePath(path));
    LocalFSStore::narFromPath(path, sink);
}

void RestrictedStore::ensurePath(const StorePath & path)
{
    if (!goal.isAllowed(path))
        throw InvalidPath("cannot substitute unknown path '%s' in recursive Nix", printStorePath(path));
    /* Nothing to be done; 'path' must already be valid. */
}

void RestrictedStore::registerDrvOutput(const Realisation & info)
// XXX: This should probably be allowed as a no-op if the realisation
// corresponds to an allowed derivation
{
    throw Error("registerDrvOutput");
}

void RestrictedStore::queryRealisationUncached(
    const DrvOutput & id, Callback<std::shared_ptr<const Realisation>> callback) noexcept
// XXX: This should probably be allowed if the realisation corresponds to
// an allowed derivation
{
    if (!goal.isAllowed(id))
        callback(nullptr);
    next->queryRealisation(id, std::move(callback));
}

void RestrictedStore::buildPaths(
    const std::vector<DerivedPath> & paths, BuildMode buildMode, std::shared_ptr<Store> evalStore)
{
    for (auto & result : buildPathsWithResults(paths, buildMode, evalStore))
        if (auto * failureP = result.tryGetFailure())
            failureP->rethrow();
}

std::vector<KeyedBuildResult> RestrictedStore::buildPathsWithResults(
    const std::vector<DerivedPath> & paths, BuildMode buildMode, std::shared_ptr<Store> evalStore)
{
    assert(!evalStore);

    if (buildMode != bmNormal)
        throw Error("unsupported build mode");

    StorePathSet newPaths;
    std::set<Realisation> newRealisations;

    for (auto & req : paths) {
        if (!goal.isAllowed(req))
            throw InvalidPath("cannot build '%s' in recursive Nix because path is unknown", req.to_string(*next));
    }

    auto results = next->buildPathsWithResults(paths, buildMode);

    for (auto & result : results) {
        if (auto * successP = result.tryGetSuccess()) {
            for (auto & [outputName, output] : successP->builtOutputs) {
                newPaths.insert(output.outPath);
                newRealisations.insert(output);
            }
        }
    }

    StorePathSet closure;
    next->computeFSClosure(newPaths, closure);
    for (auto & path : closure)
        goal.addDependency(path);
    for (auto & real : Realisation::closure(*next, newRealisations))
        goal.addedDrvOutputs.insert(real.id);

    return results;
}

MissingPaths RestrictedStore::queryMissing(const std::vector<DerivedPath> & targets)
{
    /* This is slightly impure since it leaks information to the
       client about what paths will be built/substituted or are
       already present. Probably not a big deal. */

    std::vector<DerivedPath> allowed;
    StorePathSet unknown;
    for (auto & req : targets) {
        if (goal.isAllowed(req))
            allowed.emplace_back(req);
        else
            unknown.insert(pathPartOfReq(req));
    }

    auto res = next->queryMissing(allowed);

    for (auto & p : unknown)
        res.unknown.insert(p);

    return res;
}

} // namespace nix