diff options
Diffstat (limited to 'src/libstore/build/local-derivation-goal.cc')
| -rw-r--r-- | src/libstore/build/local-derivation-goal.cc | 2829 |
1 files changed, 2829 insertions, 0 deletions
diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc new file mode 100644 index 000000000..b4137839d --- /dev/null +++ b/src/libstore/build/local-derivation-goal.cc @@ -0,0 +1,2829 @@ +#include "local-derivation-goal.hh" +#include "hook-instance.hh" +#include "worker.hh" +#include "builtins.hh" +#include "builtins/buildenv.hh" +#include "references.hh" +#include "finally.hh" +#include "util.hh" +#include "archive.hh" +#include "json.hh" +#include "compression.hh" +#include "daemon.hh" +#include "worker-protocol.hh" +#include "topo-sort.hh" +#include "callback.hh" + +#include <regex> +#include <queue> + +#include <sys/un.h> +#include <fcntl.h> +#include <termios.h> +#include <unistd.h> +#include <sys/mman.h> +#include <sys/utsname.h> +#include <sys/resource.h> + +#if HAVE_STATVFS +#include <sys/statvfs.h> +#endif + +/* Includes required for chroot support. */ +#if __linux__ +#include <sys/ioctl.h> +#include <net/if.h> +#include <netinet/ip.h> +#include <sys/personality.h> +#include <sys/mman.h> +#include <sched.h> +#include <sys/param.h> +#include <sys/mount.h> +#include <sys/syscall.h> +#if HAVE_SECCOMP +#include <seccomp.h> +#endif +#define pivot_root(new_root, put_old) (syscall(SYS_pivot_root, new_root, put_old)) +#endif + +#if __APPLE__ +#include <spawn.h> +#include <sys/sysctl.h> +#endif + +#include <pwd.h> +#include <grp.h> + +#include <nlohmann/json.hpp> + +namespace nix { + +void handleDiffHook( + uid_t uid, uid_t gid, + const Path & tryA, const Path & tryB, + const Path & drvPath, const Path & tmpDir) +{ + auto diffHook = settings.diffHook; + if (diffHook != "" && settings.runDiffHook) { + try { + auto diffRes = runProgram(RunOptions { + .program = diffHook, + .searchPath = true, + .args = {tryA, tryB, drvPath, tmpDir}, + .uid = uid, + .gid = gid, + .chdir = "/" + }); + if (!statusOk(diffRes.first)) + throw ExecError(diffRes.first, + "diff-hook program '%1%' %2%", + diffHook, + statusToString(diffRes.first)); + + if (diffRes.second != "") + printError(chomp(diffRes.second)); + } catch (Error & error) { + ErrorInfo ei = error.info(); + // FIXME: wrap errors. + ei.msg = hintfmt("diff hook execution failed: %s", ei.msg.str()); + logError(ei); + } + } +} + +const Path LocalDerivationGoal::homeDir = "/homeless-shelter"; + + +LocalDerivationGoal::~LocalDerivationGoal() +{ + /* Careful: we should never ever throw an exception from a + destructor. */ + try { deleteTmpDir(false); } catch (...) { ignoreException(); } + try { killChild(); } catch (...) { ignoreException(); } + try { stopDaemon(); } catch (...) { ignoreException(); } +} + + +inline bool LocalDerivationGoal::needsHashRewrite() +{ +#if __linux__ + return !useChroot; +#else + /* Darwin requires hash rewriting even when sandboxing is enabled. */ + return true; +#endif +} + + +LocalStore & LocalDerivationGoal::getLocalStore() +{ + auto p = dynamic_cast<LocalStore *>(&worker.store); + assert(p); + return *p; +} + + +void LocalDerivationGoal::killChild() +{ + if (pid != -1) { + worker.childTerminated(this); + + if (buildUser) { + /* If we're using a build user, then there is a tricky + race condition: if we kill the build user before the + child has done its setuid() to the build user uid, then + it won't be killed, and we'll potentially lock up in + pid.wait(). So also send a conventional kill to the + child. */ + ::kill(-pid, SIGKILL); /* ignore the result */ + buildUser->kill(); + pid.wait(); + } else + pid.kill(); + + assert(pid == -1); + } + + DerivationGoal::killChild(); +} + + +void LocalDerivationGoal::tryLocalBuild() { + unsigned int curBuilds = worker.getNrLocalBuilds(); + if (curBuilds >= settings.maxBuildJobs) { + state = &DerivationGoal::tryToBuild; + worker.waitForBuildSlot(shared_from_this()); + outputLocks.unlock(); + return; + } + + if (useBuildUsers()) { + if (!buildUser) + buildUser = acquireUserLock(); + + if (!buildUser) { + if (!actLock) + actLock = std::make_unique<Activity>(*logger, lvlWarn, actBuildWaiting, + fmt("waiting for UID to build '%s'", yellowtxt(worker.store.printStorePath(drvPath)))); + worker.waitForAWhile(shared_from_this()); + return; + } + + /* Make sure that no other processes are executing under this + uid. */ + buildUser->kill(); + } + + actLock.reset(); + + try { + + /* Okay, we have to build. */ + startBuilder(); + + } catch (BuildError & e) { + outputLocks.unlock(); + buildUser.reset(); + worker.permanentFailure = true; + done(BuildResult::InputRejected, e); + return; + } + + /* This state will be reached when we get EOF on the child's + log pipe. */ + state = &DerivationGoal::buildDone; + + started(); +} + +static void chmod_(const Path & path, mode_t mode) +{ + if (chmod(path.c_str(), mode) == -1) + throw SysError("setting permissions on '%s'", path); +} + + +/* Move/rename path 'src' to 'dst'. Temporarily make 'src' writable if + it's a directory and we're not root (to be able to update the + directory's parent link ".."). */ +static void movePath(const Path & src, const Path & dst) +{ + auto st = lstat(src); + + bool changePerm = (geteuid() && S_ISDIR(st.st_mode) && !(st.st_mode & S_IWUSR)); + + if (changePerm) + chmod_(src, st.st_mode | S_IWUSR); + + if (rename(src.c_str(), dst.c_str())) + throw SysError("renaming '%1%' to '%2%'", src, dst); + + if (changePerm) + chmod_(dst, st.st_mode); +} + + +extern void replaceValidPath(const Path & storePath, const Path & tmpPath); + + +int LocalDerivationGoal::getChildStatus() +{ + return hook ? DerivationGoal::getChildStatus() : pid.kill(); +} + +void LocalDerivationGoal::closeReadPipes() +{ + if (hook) { + DerivationGoal::closeReadPipes(); + } else + builderOut.readSide = -1; +} + + +void LocalDerivationGoal::cleanupHookFinally() +{ + /* Release the build user at the end of this function. We don't do + it right away because we don't want another build grabbing this + uid and then messing around with our output. */ + buildUser.reset(); +} + + +void LocalDerivationGoal::cleanupPreChildKill() +{ + sandboxMountNamespace = -1; +} + + +void LocalDerivationGoal::cleanupPostChildKill() +{ + /* When running under a build user, make sure that all processes + running under that uid are gone. This is to prevent a + malicious user from leaving behind a process that keeps files + open and modifies them after they have been chown'ed to + root. */ + if (buildUser) buildUser->kill(); + + /* Terminate the recursive Nix daemon. */ + stopDaemon(); +} + + +bool LocalDerivationGoal::cleanupDecideWhetherDiskFull() +{ + bool diskFull = false; + + /* Heuristically check whether the build failure may have + been caused by a disk full condition. We have no way + of knowing whether the build actually got an ENOSPC. + So instead, check if the disk is (nearly) full now. If + so, we don't mark this build as a permanent failure. */ +#if HAVE_STATVFS + { + auto & localStore = getLocalStore(); + uint64_t required = 8ULL * 1024 * 1024; // FIXME: make configurable + struct statvfs st; + if (statvfs(localStore.realStoreDir.get().c_str(), &st) == 0 && + (uint64_t) st.f_bavail * st.f_bsize < required) + diskFull = true; + if (statvfs(tmpDir.c_str(), &st) == 0 && + (uint64_t) st.f_bavail * st.f_bsize < required) + diskFull = true; + } +#endif + + deleteTmpDir(false); + + /* Move paths out of the chroot for easier debugging of + build failures. */ + if (useChroot && buildMode == bmNormal) + for (auto & [_, status] : initialOutputs) { + if (!status.known) continue; + if (buildMode != bmCheck && status.known->isValid()) continue; + auto p = worker.store.printStorePath(status.known->path); + if (pathExists(chrootRootDir + p)) + rename((chrootRootDir + p).c_str(), p.c_str()); + } + + return diskFull; +} + + +void LocalDerivationGoal::cleanupPostOutputsRegisteredModeCheck() +{ + deleteTmpDir(true); +} + + +void LocalDerivationGoal::cleanupPostOutputsRegisteredModeNonCheck() +{ + /* Delete unused redirected outputs (when doing hash rewriting). */ + for (auto & i : redirectedOutputs) + deletePath(worker.store.Store::toRealPath(i.second)); + + /* Delete the chroot (if we were using one). */ + autoDelChroot.reset(); /* this runs the destructor */ + + cleanupPostOutputsRegisteredModeCheck(); +} + + +int childEntry(void * arg) +{ + ((LocalDerivationGoal *) arg)->runChild(); + return 1; +} + + +static void linkOrCopy(const Path & from, const Path & to) +{ + if (link(from.c_str(), to.c_str()) == -1) { + /* Hard-linking fails if we exceed the maximum link count on a + file (e.g. 32000 of ext3), which is quite possible after a + 'nix-store --optimise'. FIXME: actually, why don't we just + bind-mount in this case? + + It can also fail with EPERM in BeegFS v7 and earlier versions + which don't allow hard-links to other directories */ + if (errno != EMLINK && errno != EPERM) + throw SysError("linking '%s' to '%s'", to, from); + copyPath(from, to); + } +} + + +void LocalDerivationGoal::startBuilder() +{ + /* Right platform? */ + if (!parsedDrv->canBuildLocally(worker.store)) + throw Error("a '%s' with features {%s} is required to build '%s', but I am a '%s' with features {%s}", + drv->platform, + concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()), + worker.store.printStorePath(drvPath), + settings.thisSystem, + concatStringsSep<StringSet>(", ", worker.store.systemFeatures)); + +#if __APPLE__ + additionalSandboxProfile = parsedDrv->getStringAttr("__sandboxProfile").value_or(""); +#endif + + /* Are we doing a chroot build? */ + { + auto noChroot = parsedDrv->getBoolAttr("__noChroot"); + if (settings.sandboxMode == smEnabled) { + if (noChroot) + throw Error("derivation '%s' has '__noChroot' set, " + "but that's not allowed when 'sandbox' is 'true'", worker.store.printStorePath(drvPath)); +#if __APPLE__ + if (additionalSandboxProfile != "") + throw Error("derivation '%s' specifies a sandbox profile, " + "but this is only allowed when 'sandbox' is 'relaxed'", worker.store.printStorePath(drvPath)); +#endif + useChroot = true; + } + else if (settings.sandboxMode == smDisabled) + useChroot = false; + else if (settings.sandboxMode == smRelaxed) + useChroot = !(derivationIsImpure(derivationType)) && !noChroot; + } + + auto & localStore = getLocalStore(); + if (localStore.storeDir != localStore.realStoreDir.get()) { + #if __linux__ + useChroot = true; + #else + throw Error("building using a diverted store is not supported on this platform"); + #endif + } + + /* Create a temporary directory where the build will take + place. */ + tmpDir = createTempDir("", "nix-build-" + std::string(drvPath.name()), false, false, 0700); + + chownToBuilder(tmpDir); + + for (auto & [outputName, status] : initialOutputs) { + /* Set scratch path we'll actually use during the build. + + If we're not doing a chroot build, but we have some valid + output paths. Since we can't just overwrite or delete + them, we have to do hash rewriting: i.e. in the + environment/arguments passed to the build, we replace the + hashes of the valid outputs with unique dummy strings; + after the build, we discard the redirected outputs + corresponding to the valid outputs, and rewrite the + contents of the new outputs to replace the dummy strings + with the actual hashes. */ + auto scratchPath = + !status.known + ? makeFallbackPath(outputName) + : !needsHashRewrite() + /* Can always use original path in sandbox */ + ? status.known->path + : !status.known->isPresent() + /* If path doesn't yet exist can just use it */ + ? status.known->path + : buildMode != bmRepair && !status.known->isValid() + /* If we aren't repairing we'll delete a corrupted path, so we + can use original path */ + ? status.known->path + : /* If we are repairing or the path is totally valid, we'll need + to use a temporary path */ + makeFallbackPath(status.known->path); + scratchOutputs.insert_or_assign(outputName, scratchPath); + + /* Substitute output placeholders with the scratch output paths. + We'll use during the build. */ + inputRewrites[hashPlaceholder(outputName)] = worker.store.printStorePath(scratchPath); + + /* Additional tasks if we know the final path a priori. */ + if (!status.known) continue; + auto fixedFinalPath = status.known->path; + + /* Additional tasks if the final and scratch are both known and + differ. */ + if (fixedFinalPath == scratchPath) continue; + + /* Ensure scratch path is ours to use. */ + deletePath(worker.store.printStorePath(scratchPath)); + + /* Rewrite and unrewrite paths */ + { + std::string h1 { fixedFinalPath.hashPart() }; + std::string h2 { scratchPath.hashPart() }; + inputRewrites[h1] = h2; + } + + redirectedOutputs.insert_or_assign(std::move(fixedFinalPath), std::move(scratchPath)); + } + + /* Construct the environment passed to the builder. */ + initEnv(); + + writeStructuredAttrs(); + + /* Handle exportReferencesGraph(), if set. */ + if (!parsedDrv->getStructuredAttrs()) { + /* The `exportReferencesGraph' feature allows the references graph + to be passed to a builder. This attribute should be a list of + pairs [name1 path1 name2 path2 ...]. The references graph of + each `pathN' will be stored in a text file `nameN' in the + temporary build directory. The text files have the format used + by `nix-store --register-validity'. However, the deriver + fields are left empty. */ + string s = get(drv->env, "exportReferencesGraph").value_or(""); + Strings ss = tokenizeString<Strings>(s); + if (ss.size() % 2 != 0) + throw BuildError("odd number of tokens in 'exportReferencesGraph': '%1%'", s); + for (Strings::iterator i = ss.begin(); i != ss.end(); ) { + string fileName = *i++; + static std::regex regex("[A-Za-z_][A-Za-z0-9_.-]*"); + if (!std::regex_match(fileName, regex)) + throw Error("invalid file name '%s' in 'exportReferencesGraph'", fileName); + + auto storePathS = *i++; + if (!worker.store.isInStore(storePathS)) + throw BuildError("'exportReferencesGraph' contains a non-store path '%1%'", storePathS); + auto storePath = worker.store.toStorePath(storePathS).first; + + /* Write closure info to <fileName>. */ + writeFile(tmpDir + "/" + fileName, + worker.store.makeValidityRegistration( + worker.store.exportReferences({storePath}, inputPaths), false, false)); + } + } + + useUidRange = parsedDrv->getRequiredSystemFeatures().count("uid-range"); + useSystemdCgroup = parsedDrv->getRequiredSystemFeatures().count("systemd-cgroup"); + + if (useChroot) { + + /* Allow a user-configurable set of directories from the + host file system. */ + dirsInChroot.clear(); + + for (auto i : settings.sandboxPaths.get()) { + if (i.empty()) continue; + bool optional = false; + if (i[i.size() - 1] == '?') { + optional = true; + i.pop_back(); + } + size_t p = i.find('='); + if (p == string::npos) + dirsInChroot[i] = {i, optional}; + else + dirsInChroot[string(i, 0, p)] = {string(i, p + 1), optional}; + } + dirsInChroot[tmpDirInSandbox] = tmpDir; + + /* Add the closure of store paths to the chroot. */ + StorePathSet closure; + for (auto & i : dirsInChroot) + try { + if (worker.store.isInStore(i.second.source)) + worker.store.computeFSClosure(worker.store.toStorePath(i.second.source).first, closure); + } catch (InvalidPath & e) { + } catch (Error & e) { + e.addTrace({}, "while processing 'sandbox-paths'"); + throw; + } + for (auto & i : closure) { + auto p = worker.store.printStorePath(i); + dirsInChroot.insert_or_assign(p, p); + } + + PathSet allowedPaths = settings.allowedImpureHostPrefixes; + + /* This works like the above, except on a per-derivation level */ + auto impurePaths = parsedDrv->getStringsAttr("__impureHostDeps").value_or(Strings()); + + for (auto & i : impurePaths) { + bool found = false; + /* Note: we're not resolving symlinks here to prevent + giving a non-root user info about inaccessible + files. */ + Path canonI = canonPath(i); + /* If only we had a trie to do this more efficiently :) luckily, these are generally going to be pretty small */ + for (auto & a : allowedPaths) { + Path canonA = canonPath(a); + if (canonI == canonA || isInDir(canonI, canonA)) { + found = true; + break; + } + } + if (!found) + throw Error("derivation '%s' requested impure path '%s', but it was not in allowed-impure-host-deps", + worker.store.printStorePath(drvPath), i); + + /* Allow files in __impureHostDeps to be missing; e.g. + macOS 11+ has no /usr/lib/libSystem*.dylib */ + dirsInChroot[i] = {i, true}; + } + +#if __linux__ + /* Create a temporary directory in which we set up the chroot + environment using bind-mounts. We put it in the Nix store + to ensure that we can create hard-links to non-directory + inputs in the fake Nix store in the chroot (see below). */ + chrootRootDir = worker.store.Store::toRealPath(drvPath) + ".chroot"; + deletePath(chrootRootDir); + + /* Clean up the chroot directory automatically. */ + autoDelChroot = std::make_shared<AutoDelete>(chrootRootDir); + + printMsg(lvlChatty, format("setting up chroot environment in '%1%'") % chrootRootDir); + + if (mkdir(chrootRootDir.c_str(), useUidRange ? 0755 : 0750) == -1) + throw SysError("cannot create '%1%'", chrootRootDir); + + // FIXME: only make root writable for user namespace builds. + if (buildUser && chown(chrootRootDir.c_str(), buildUser->getUID(), buildUser->getGID()) == -1) + throw SysError("cannot change ownership of '%1%'", chrootRootDir); + + /* Create a writable /tmp in the chroot. Many builders need + this. (Of course they should really respect $TMPDIR + instead.) */ + Path chrootTmpDir = chrootRootDir + "/tmp"; + createDirs(chrootTmpDir); + chmod_(chrootTmpDir, 01777); + + /* Create a /etc/passwd with entries for the build user and the + nobody account. The latter is kind of a hack to support + Samba-in-QEMU. */ + createDirs(chrootRootDir + "/etc"); + chownToBuilder(chrootRootDir + "/etc"); + + if (useUidRange && (!buildUser || buildUser->getUIDCount() < 65536)) + throw Error("feature 'uid-range' requires '%s' to be enabled", settings.autoAllocateUids.name); + + /* Declare the build user's group so that programs get a consistent + view of the system (e.g., "id -gn"). */ + writeFile(chrootRootDir + "/etc/group", + fmt("root:x:0:\n" + "nixbld:!:%1%:\n" + "nogroup:x:65534:\n", sandboxGid())); + + /* Create /etc/hosts with localhost entry. */ + if (!(derivationIsImpure(derivationType))) + writeFile(chrootRootDir + "/etc/hosts", "127.0.0.1 localhost\n::1 localhost\n"); + + /* Make the closure of the inputs available in the chroot, + rather than the whole Nix store. This prevents any access + to undeclared dependencies. Directories are bind-mounted, + while other inputs are hard-linked (since only directories + can be bind-mounted). !!! As an extra security + precaution, make the fake Nix store only writable by the + build user. */ + Path chrootStoreDir = chrootRootDir + worker.store.storeDir; + createDirs(chrootStoreDir); + chmod_(chrootStoreDir, 01775); + + if (buildUser && chown(chrootStoreDir.c_str(), 0, buildUser->getGID()) == -1) + throw SysError("cannot change ownership of '%1%'", chrootStoreDir); + + for (auto & i : inputPaths) { + auto p = worker.store.printStorePath(i); + Path r = worker.store.toRealPath(p); + if (S_ISDIR(lstat(r).st_mode)) + dirsInChroot.insert_or_assign(p, r); + else + linkOrCopy(r, chrootRootDir + p); + } + + /* If we're repairing, checking or rebuilding part of a + multiple-outputs derivation, it's possible that we're + rebuilding a path that is in settings.dirsInChroot + (typically the dependencies of /bin/sh). Throw them + out. */ + for (auto & i : drv->outputsAndOptPaths(worker.store)) { + /* If the name isn't known a priori (i.e. floating + content-addressed derivation), the temporary location we use + should be fresh. Freshness means it is impossible that the path + is already in the sandbox, so we don't need to worry about + removing it. */ + if (i.second.second) + dirsInChroot.erase(worker.store.printStorePath(*i.second.second)); + } + + if (useSystemdCgroup) { + settings.requireExperimentalFeature("systemd-cgroup"); + std::optional<Path> cgroup; + if (!buildUser || !(cgroup = buildUser->getCgroup())) + throw Error("feature 'systemd-cgroup' requires 'auto-allocate-uids = true' in nix.conf"); + chownToBuilder(*cgroup); + chownToBuilder(*cgroup + "/cgroup.procs"); + } + +#else + if (useUidRange) + throw Error("feature 'uid-range' is not supported on this platform"); + if (useSystemdCgroup) + throw Error("feature 'systemd-cgroup' is not supported on this platform"); + #if __APPLE__ + /* We don't really have any parent prep work to do (yet?) + All work happens in the child, instead. */ + #else + throw Error("sandboxing builds is not supported on this platform"); + #endif +#endif + } else { + if (useUidRange) + throw Error("feature 'uid-range' is only supported in sandboxed builds"); + if (useSystemdCgroup) + throw Error("feature 'systemd-cgroup' is only supported in sandboxed builds"); + } + + if (needsHashRewrite() && pathExists(homeDir)) + throw Error("home directory '%1%' exists; please remove it to assure purity of builds without sandboxing", homeDir); + + if (useChroot && settings.preBuildHook != "" && dynamic_cast<Derivation *>(drv.get())) { + printMsg(lvlChatty, format("executing pre-build hook '%1%'") + % settings.preBuildHook); + auto args = useChroot ? Strings({worker.store.printStorePath(drvPath), chrootRootDir}) : + Strings({ worker.store.printStorePath(drvPath) }); + enum BuildHookState { + stBegin, + stExtraChrootDirs + }; + auto state = stBegin; + auto lines = runProgram(settings.preBuildHook, false, args); + auto lastPos = std::string::size_type{0}; + for (auto nlPos = lines.find('\n'); nlPos != string::npos; + nlPos = lines.find('\n', lastPos)) { + auto line = std::string{lines, lastPos, nlPos - lastPos}; + lastPos = nlPos + 1; + if (state == stBegin) { + if (line == "extra-sandbox-paths" || line == "extra-chroot-dirs") { + state = stExtraChrootDirs; + } else { + throw Error("unknown pre-build hook command '%1%'", line); + } + } else if (state == stExtraChrootDirs) { + if (line == "") { + state = stBegin; + } else { + auto p = line.find('='); + if (p == string::npos) + dirsInChroot[line] = line; + else + dirsInChroot[string(line, 0, p)] = string(line, p + 1); + } + } + } + } + + /* Fire up a Nix daemon to process recursive Nix calls from the + builder. */ + if (parsedDrv->getRequiredSystemFeatures().count("recursive-nix")) + startDaemon(); + + /* Run the builder. */ + printMsg(lvlChatty, "executing builder '%1%'", drv->builder); + + /* Create the log file. */ + Path logFile = openLogFile(); + + /* Create a pipe to get the output of the builder. */ + //builderOut.create(); + + builderOut.readSide = posix_openpt(O_RDWR | O_NOCTTY); + if (!builderOut.readSide) + throw SysError("opening pseudoterminal master"); + + std::string slaveName(ptsname(builderOut.readSide.get())); + + if (buildUser) { + if (chmod(slaveName.c_str(), 0600)) + throw SysError("changing mode of pseudoterminal slave"); + + if (chown(slaveName.c_str(), buildUser->getUID(), 0)) + throw SysError("changing owner of pseudoterminal slave"); + } +#if __APPLE__ + else { + if (grantpt(builderOut.readSide.get())) + throw SysError("granting access to pseudoterminal slave"); + } +#endif + + #if 0 + // Mount the pt in the sandbox so that the "tty" command works. + // FIXME: this doesn't work with the new devpts in the sandbox. + if (useChroot) + dirsInChroot[slaveName] = {slaveName, false}; + #endif + + if (unlockpt(builderOut.readSide.get())) + throw SysError("unlocking pseudoterminal"); + + builderOut.writeSide = open(slaveName.c_str(), O_RDWR | O_NOCTTY); + if (!builderOut.writeSide) + throw SysError("opening pseudoterminal slave"); + + // Put the pt into raw mode to prevent \n -> \r\n translation. + struct termios term; + if (tcgetattr(builderOut.writeSide.get(), &term)) + throw SysError("getting pseudoterminal attributes"); + + cfmakeraw(&term); + + if (tcsetattr(builderOut.writeSide.get(), TCSANOW, &term)) + throw SysError("putting pseudoterminal into raw mode"); + + result.startTime = time(0); + + /* Fork a child to build the package. */ + ProcessOptions options; + +#if __linux__ + if (useChroot) { + /* Set up private namespaces for the build: + + - The PID namespace causes the build to start as PID 1. + Processes outside of the chroot are not visible to those + on the inside, but processes inside the chroot are + visible from the outside (though with different PIDs). + + - The private mount namespace ensures that all the bind + mounts we do will only show up in this process and its + children, and will disappear automatically when we're + done. + + - The private network namespace ensures that the builder + cannot talk to the outside world (or vice versa). It + only has a private loopback interface. (Fixed-output + derivations are not run in a private network namespace + to allow functions like fetchurl to work.) + + - The IPC namespace prevents the builder from communicating + with outside processes using SysV IPC mechanisms (shared + memory, message queues, semaphores). It also ensures + that all IPC objects are destroyed when the builder + exits. + + - The UTS namespace ensures that builders see a hostname of + localhost rather than the actual hostname. + + We use a helper process to do the clone() to work around + clone() being broken in multi-threaded programs due to + at-fork handlers not being run. Note that we use + CLONE_PARENT to ensure that the real builder is parented to + us. + */ + + if (!(derivationIsImpure(derivationType))) + privateNetwork = true; + + userNamespaceSync.create(); + + options.allowVfork = false; + + Path maxUserNamespaces = "/proc/sys/user/max_user_namespaces"; + static bool userNamespacesEnabled = + pathExists(maxUserNamespaces) + && trim(readFile(maxUserNamespaces)) != "0"; + + usingUserNamespace = userNamespacesEnabled; + + Pid helper = startProcess([&]() { + + /* Drop additional groups here because we can't do it + after we've created the new user namespace. FIXME: + this means that if we're not root in the parent + namespace, we can't drop additional groups; they will + be mapped to nogroup in the child namespace. There does + not seem to be a workaround for this. (But who can tell + from reading user_namespaces(7)?) + See also https://lwn.net/Articles/621612/. */ + if (getuid() == 0 && setgroups(0, 0) == -1) + throw SysError("setgroups failed"); + + size_t stackSize = 1 * 1024 * 1024; + char * stack = (char *) mmap(0, stackSize, + PROT_WRITE | PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0); + if (stack == MAP_FAILED) throw SysError("allocating stack"); + + int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | CLONE_NEWUTS | CLONE_PARENT | SIGCHLD; + if (privateNetwork) + flags |= CLONE_NEWNET; + if (usingUserNamespace) + flags |= CLONE_NEWUSER; + + pid_t child = clone(childEntry, stack + stackSize, flags, this); + if (child == -1 && errno == EINVAL) { + /* Fallback for Linux < 2.13 where CLONE_NEWPID and + CLONE_PARENT are not allowed together. */ + flags &= ~CLONE_NEWPID; + child = clone(childEntry, stack + stackSize, flags, this); + } + if (usingUserNamespace && child == -1 && (errno == EPERM || errno == EINVAL)) { + /* Some distros patch Linux to not allow unprivileged + * user namespaces. If we get EPERM or EINVAL, try + * without CLONE_NEWUSER and see if that works. + */ + usingUserNamespace = false; + flags &= ~CLONE_NEWUSER; + child = clone(childEntry, stack + stackSize, flags, this); + } + /* Otherwise exit with EPERM so we can handle this in the + parent. This is only done when sandbox-fallback is set + to true (the default). */ + if (child == -1 && (errno == EPERM || errno == EINVAL) && settings.sandboxFallback) + _exit(1); + if (child == -1) throw SysError("cloning builder process"); + + writeFull(builderOut.writeSide.get(), + fmt("%d %d\n", usingUserNamespace, child)); + _exit(0); + }, options); + + int res = helper.wait(); + if (res != 0 && settings.sandboxFallback) { + useChroot = false; + initTmpDir(); + goto fallback; + } else if (res != 0) + throw Error("unable to start build process"); + + userNamespaceSync.readSide = -1; + + /* Close the write side to prevent runChild() from hanging + reading from this. */ + Finally cleanup([&]() { + userNamespaceSync.writeSide = -1; + }); + + auto ss = tokenizeString<std::vector<std::string>>(readLine(builderOut.readSide.get())); + assert(ss.size() == 2); + usingUserNamespace = ss[0] == "1"; + pid = string2Int<pid_t>(ss[1]).value(); + + if (usingUserNamespace) { + /* Set the UID/GID mapping of the builder's user namespace + such that the sandbox user maps to the build user, or to + the calling user (if build users are disabled). */ + uid_t hostUid = buildUser ? buildUser->getUID() : getuid(); + uid_t hostGid = buildUser ? buildUser->getGID() : getgid(); + uint32_t nrIds = buildUser && useUidRange ? buildUser->getUIDCount() : 1; + + writeFile("/proc/" + std::to_string(pid) + "/uid_map", + fmt("%d %d %d", sandboxUid(), hostUid, nrIds)); + + if (!useUidRange) + writeFile("/proc/" + std::to_string(pid) + "/setgroups", "deny"); + + writeFile("/proc/" + std::to_string(pid) + "/gid_map", + fmt("%d %d %d", sandboxGid(), hostGid, nrIds)); + } else { + debug("note: not using a user namespace"); + if (!buildUser) + throw Error("cannot perform a sandboxed build because user namespaces are not enabled; check /proc/sys/user/max_user_namespaces"); + } + + /* Now that we now the sandbox uid, we can write + /etc/passwd. */ + writeFile(chrootRootDir + "/etc/passwd", fmt( + "root:x:0:0:Nix build user:%3%:/noshell\n" + "nixbld:x:%1%:%2%:Nix build user:%3%:/noshell\n" + "nobody:x:65534:65534:Nobody:/:/noshell\n", + sandboxUid(), sandboxGid(), settings.sandboxBuildDir)); + + /* Save the mount namespace of the child. We have to do this + *before* the child does a chroot. */ + sandboxMountNamespace = open(fmt("/proc/%d/ns/mnt", (pid_t) pid).c_str(), O_RDONLY); + if (sandboxMountNamespace.get() == -1) + throw SysError("getting sandbox mount namespace"); + + /* Move the child into its own cgroup. */ + if (buildUser) { + if (auto cgroup = buildUser->getCgroup()) + writeFile(*cgroup + "/cgroup.procs", fmt("%d", (pid_t) pid)); + } + + /* Signal the builder that we've updated its user namespace. */ + writeFull(userNamespaceSync.writeSide.get(), "1"); + + } else +#endif + { + fallback: + options.allowVfork = !buildUser && !drv->isBuiltin(); + pid = startProcess([&]() { + runChild(); + }, options); + } + + /* parent */ + pid.setSeparatePG(true); + builderOut.writeSide = -1; + worker.childStarted(shared_from_this(), {builderOut.readSide.get()}, true, true); + + /* Check if setting up the build environment failed. */ + std::vector<std::string> msgs; + while (true) { + string msg = [&]() { + try { + return readLine(builderOut.readSide.get()); + } catch (Error & e) { + e.addTrace({}, "while waiting for the build environment to initialize (previous messages: %s)", + concatStringsSep("|", msgs)); + throw e; + } + }(); + if (string(msg, 0, 1) == "\2") break; + if (string(msg, 0, 1) == "\1") { + FdSource source(builderOut.readSide.get()); + auto ex = readError(source); + ex.addTrace({}, "while setting up the build environment"); + throw ex; + } + debug("sandbox setup: " + msg); + msgs.push_back(std::move(msg)); + } +} + + +void LocalDerivationGoal::initTmpDir() { + /* In a sandbox, for determinism, always use the same temporary + directory. */ +#if __linux__ + tmpDirInSandbox = useChroot ? settings.sandboxBuildDir : tmpDir; +#else + tmpDirInSandbox = tmpDir; +#endif + + /* In non-structured mode, add all bindings specified in the + derivation via the environment, except those listed in the + passAsFile attribute. Those are passed as file names pointing + to temporary files containing the contents. Note that + passAsFile is ignored in structure mode because it's not + needed (attributes are not passed through the environment, so + there is no size constraint). */ + if (!parsedDrv->getStructuredAttrs()) { + + StringSet passAsFile = tokenizeString<StringSet>(get(drv->env, "passAsFile").value_or("")); + for (auto & i : drv->env) { + if (passAsFile.find(i.first) == passAsFile.end()) { + env[i.first] = i.second; + } else { + auto hash = hashString(htSHA256, i.first); + string fn = ".attr-" + hash.to_string(Base32, false); + Path p = tmpDir + "/" + fn; + writeFile(p, rewriteStrings(i.second, inputRewrites)); + chownToBuilder(p); + env[i.first + "Path"] = tmpDirInSandbox + "/" + fn; + } + } + + } + + /* For convenience, set an environment pointing to the top build + directory. */ + env["NIX_BUILD_TOP"] = tmpDirInSandbox; + + /* Also set TMPDIR and variants to point to this directory. */ + env["TMPDIR"] = env["TEMPDIR"] = env["TMP"] = env["TEMP"] = tmpDirInSandbox; + + /* Explicitly set PWD to prevent problems with chroot builds. In + particular, dietlibc cannot figure out the cwd because the + inode of the current directory doesn't appear in .. (because + getdents returns the inode of the mount point). */ + env["PWD"] = tmpDirInSandbox; +} + + +void LocalDerivationGoal::initEnv() +{ + env.clear(); + + /* Most shells initialise PATH to some default (/bin:/usr/bin:...) when + PATH is not set. We don't want this, so we fill it in with some dummy + value. */ + env["PATH"] = "/path-not-set"; + + /* Set HOME to a non-existing path to prevent certain programs from using + /etc/passwd (or NIS, or whatever) to locate the home directory (for + example, wget looks for ~/.wgetrc). I.e., these tools use /etc/passwd + if HOME is not set, but they will just assume that the settings file + they are looking for does not exist if HOME is set but points to some + non-existing path. */ + env["HOME"] = homeDir; + + /* Tell the builder where the Nix store is. Usually they + shouldn't care, but this is useful for purity checking (e.g., + the compiler or linker might only want to accept paths to files + in the store or in the build directory). */ + env["NIX_STORE"] = worker.store.storeDir; + + /* The maximum number of cores to utilize for parallel building. */ + env["NIX_BUILD_CORES"] = (format("%d") % settings.buildCores).str(); + + initTmpDir(); + + /* Compatibility hack with Nix <= 0.7: if this is a fixed-output + derivation, tell the builder, so that for instance `fetchurl' + can skip checking the output. On older Nixes, this environment + variable won't be set, so `fetchurl' will do the check. */ + if (derivationIsFixed(derivationType)) env["NIX_OUTPUT_CHECKED"] = "1"; + + /* *Only* if this is a fixed-output derivation, propagate the + values of the environment variables specified in the + `impureEnvVars' attribute to the builder. This allows for + instance environment variables for proxy configuration such as + `http_proxy' to be easily passed to downloaders like + `fetchurl'. Passing such environment variables from the caller + to the builder is generally impure, but the output of + fixed-output derivations is by definition pure (since we + already know the cryptographic hash of the output). */ + if (derivationIsImpure(derivationType)) { + for (auto & i : parsedDrv->getStringsAttr("impureEnvVars").value_or(Strings())) + env[i] = getEnv(i).value_or(""); + } + + /* Currently structured log messages piggyback on stderr, but we + may change that in the future. So tell the builder which file + descriptor to use for that. */ + env["NIX_LOG_FD"] = "2"; + + /* Trigger colored output in various tools. */ + env["TERM"] = "xterm-256color"; +} + + +void LocalDerivationGoal::writeStructuredAttrs() +{ + if (auto structAttrsJson = parsedDrv->prepareStructuredAttrs(worker.store, inputPaths)) { + auto json = structAttrsJson.value(); + nlohmann::json rewritten; + for (auto & [i, v] : json["outputs"].get<nlohmann::json::object_t>()) { + /* The placeholder must have a rewrite, so we use it to cover both the + cases where we know or don't know the output path ahead of time. */ + rewritten[i] = rewriteStrings(v, inputRewrites); + } + + json["outputs"] = rewritten; + + auto jsonSh = writeStructuredAttrsShell(json); + + writeFile(tmpDir + "/.attrs.sh", rewriteStrings(jsonSh, inputRewrites)); + chownToBuilder(tmpDir + "/.attrs.sh"); + env["NIX_ATTRS_SH_FILE"] = tmpDir + "/.attrs.sh"; + writeFile(tmpDir + "/.attrs.json", rewriteStrings(json.dump(), inputRewrites)); + chownToBuilder(tmpDir + "/.attrs.json"); + env["NIX_ATTRS_JSON_FILE"] = tmpDir + "/.attrs.json"; + } +} + + +static StorePath pathPartOfReq(const DerivedPath & req) +{ + return std::visit(overloaded { + [&](DerivedPath::Opaque bo) { + return bo.path; + }, + [&](DerivedPath::Built bfd) { + return bfd.drvPath; + }, + }, req.raw()); +} + + +bool LocalDerivationGoal::isAllowed(const DerivedPath & req) +{ + return this->isAllowed(pathPartOfReq(req)); +} + + +struct RestrictedStoreConfig : virtual LocalFSStoreConfig +{ + using LocalFSStoreConfig::LocalFSStoreConfig; + const std::string name() { return "Restricted Store"; } +}; + +/* 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 RestrictedStoreConfig, public virtual LocalFSStore +{ + ref<LocalStore> next; + + LocalDerivationGoal & goal; + + RestrictedStore(const Params & params, ref<LocalStore> next, LocalDerivationGoal & goal) + : StoreConfig(params) + , LocalFSStoreConfig(params) + , RestrictedStoreConfig(params) + , Store(params) + , LocalFSStore(params) + , next(next), goal(goal) + { } + + Path getRealStoreDir() override + { return next->realStoreDir; } + + std::string getUri() override + { return next->getUri(); } + + StorePathSet queryAllValidPaths() override + { + StorePathSet paths; + for (auto & p : goal.inputPaths) paths.insert(p); + for (auto & p : goal.addedPaths) paths.insert(p); + return paths; + } + + void queryPathInfoUncached(const StorePath & path, + Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept override + { + 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 queryReferrers(const StorePath & path, StorePathSet & referrers) override + { } + + std::map<std::string, std::optional<StorePath>> queryPartialDerivationOutputMap(const StorePath & path) override + { + if (!goal.isAllowed(path)) + throw InvalidPath("cannot query output map for unknown path '%s' in recursive Nix", printStorePath(path)); + return next->queryPartialDerivationOutputMap(path); + } + + std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override + { throw Error("queryPathFromHashPart"); } + + StorePath addToStore(const string & name, const Path & srcPath, + FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, + PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override + { throw Error("addToStore"); } + + void addToStore(const ValidPathInfo & info, Source & narSource, + RepairFlag repair = NoRepair, CheckSigsFlag checkSigs = CheckSigs) override + { + next->addToStore(info, narSource, repair, checkSigs); + goal.addDependency(info.path); + } + + StorePath addTextToStore(const string & name, const string & s, + const StorePathSet & references, RepairFlag repair = NoRepair) override + { + auto path = next->addTextToStore(name, s, references, repair); + goal.addDependency(path); + return path; + } + + StorePath addToStoreFromDump(Source & dump, const string & name, + FileIngestionMethod method = FileIngestionMethod::Recursive, HashType hashAlgo = htSHA256, RepairFlag repair = NoRepair) override + { + auto path = next->addToStoreFromDump(dump, name, method, hashAlgo, repair); + goal.addDependency(path); + return path; + } + + void narFromPath(const StorePath & path, Sink & sink) override + { + if (!goal.isAllowed(path)) + throw InvalidPath("cannot dump unknown path '%s' in recursive Nix", printStorePath(path)); + LocalFSStore::narFromPath(path, sink); + } + + void ensurePath(const StorePath & path) override + { + 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 registerDrvOutput(const Realisation & info) override + // XXX: This should probably be allowed as a no-op if the realisation + // corresponds to an allowed derivation + { throw Error("registerDrvOutput"); } + + std::optional<const Realisation> queryRealisation(const DrvOutput & id) override + // XXX: This should probably be allowed if the realisation corresponds to + // an allowed derivation + { + if (!goal.isAllowed(id)) + throw InvalidPath("cannot query an unknown output id '%s' in recursive Nix", id.to_string()); + return next->queryRealisation(id); + } + + void buildPaths(const std::vector<DerivedPath> & paths, BuildMode buildMode, std::shared_ptr<Store> evalStore) override + { + 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)); + } + + next->buildPaths(paths, buildMode); + + for (auto & path : paths) { + auto p = std::get_if<DerivedPath::Built>(&path); + if (!p) continue; + auto & bfd = *p; + auto drv = readDerivation(bfd.drvPath); + auto drvHashes = staticOutputHashes(*this, drv); + auto outputs = next->queryDerivationOutputMap(bfd.drvPath); + for (auto & [outputName, outputPath] : outputs) + if (wantOutput(outputName, bfd.outputs)) { + newPaths.insert(outputPath); + if (settings.isExperimentalFeatureEnabled("ca-derivations")) { + auto thisRealisation = next->queryRealisation( + DrvOutput{drvHashes.at(outputName), outputName} + ); + assert(thisRealisation); + newRealisations.insert(*thisRealisation); + } + } + } + + 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); + } + + 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"); } + + void queryMissing(const std::vector<DerivedPath> & targets, + StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown, + uint64_t & downloadSize, uint64_t & narSize) override + { + /* 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; + for (auto & req : targets) { + if (goal.isAllowed(req)) + allowed.emplace_back(req); + else + unknown.insert(pathPartOfReq(req)); + } + + next->queryMissing(allowed, willBuild, willSubstitute, + unknown, downloadSize, narSize); + } +}; + + +void LocalDerivationGoal::startDaemon() +{ + settings.requireExperimentalFeature("recursive-nix"); + + Store::Params params; + params["path-info-cache-size"] = "0"; + params["store"] = worker.store.storeDir; + params["root"] = getLocalStore().rootDir; + params["state"] = "/no-such-path"; + params["log"] = "/no-such-path"; + auto store = make_ref<RestrictedStore>(params, + ref<LocalStore>(std::dynamic_pointer_cast<LocalStore>(worker.store.shared_from_this())), + *this); + + addedPaths.clear(); + + auto socketName = ".nix-socket"; + Path socketPath = tmpDir + "/" + socketName; + env["NIX_REMOTE"] = "unix://" + tmpDirInSandbox + "/" + socketName; + + daemonSocket = createUnixDomainSocket(socketPath, 0600); + + chownToBuilder(socketPath); + + daemonThread = std::thread([this, store]() { + + while (true) { + + /* Accept a connection. */ + struct sockaddr_un remoteAddr; + socklen_t remoteAddrLen = sizeof(remoteAddr); + + AutoCloseFD remote = accept(daemonSocket.get(), + (struct sockaddr *) &remoteAddr, &remoteAddrLen); + if (!remote) { + if (errno == EINTR) continue; + if (errno == EINVAL) break; + throw SysError("accepting connection"); + } + + closeOnExec(remote.get()); + + debug("received daemon connection"); + + auto workerThread = std::thread([store, remote{std::move(remote)}]() { + FdSource from(remote.get()); + FdSink to(remote.get()); + try { + daemon::processConnection(store, from, to, + daemon::NotTrusted, daemon::Recursive, + [&](Store & store) { store.createUser("nobody", 65535); }); + debug("terminated daemon connection"); + } catch (SysError &) { + ignoreException(); + } + }); + + daemonWorkerThreads.push_back(std::move(workerThread)); + } + + debug("daemon shutting down"); + }); +} + + +void LocalDerivationGoal::stopDaemon() +{ + if (daemonSocket && shutdown(daemonSocket.get(), SHUT_RDWR) == -1) + throw SysError("shutting down daemon socket"); + + if (daemonThread.joinable()) + daemonThread.join(); + + // FIXME: should prune worker threads more quickly. + // FIXME: shutdown the client socket to speed up worker termination. + for (auto & thread : daemonWorkerThreads) + thread.join(); + daemonWorkerThreads.clear(); + + daemonSocket = -1; +} + + +void LocalDerivationGoal::addDependency(const StorePath & path) +{ + if (isAllowed(path)) return; + + addedPaths.insert(path); + + /* If we're doing a sandbox build, then we have to make the path + appear in the sandbox. */ + if (useChroot) { + + debug("materialising '%s' in the sandbox", worker.store.printStorePath(path)); + + #if __linux__ + + Path source = worker.store.Store::toRealPath(path); + Path target = chrootRootDir + worker.store.printStorePath(path); + debug("bind-mounting %s -> %s", target, source); + + if (pathExists(target)) + throw Error("store path '%s' already exists in the sandbox", worker.store.printStorePath(path)); + + auto st = lstat(source); + + if (S_ISDIR(st.st_mode)) { + + /* Bind-mount the path into the sandbox. This requires + entering its mount namespace, which is not possible + in multithreaded programs. So we do this in a + child process.*/ + Pid child(startProcess([&]() { + + if (setns(sandboxMountNamespace.get(), 0) == -1) + throw SysError("entering sandbox mount namespace"); + + createDirs(target); + + if (mount(source.c_str(), target.c_str(), "", MS_BIND, 0) == -1) + throw SysError("bind mount from '%s' to '%s' failed", source, target); + + _exit(0); + })); + + int status = child.wait(); + if (status != 0) + throw Error("could not add path '%s' to sandbox", worker.store.printStorePath(path)); + + } else + linkOrCopy(source, target); + + #else + throw Error("don't know how to make path '%s' (produced by a recursive Nix call) appear in the sandbox", + worker.store.printStorePath(path)); + #endif + + } +} + +void LocalDerivationGoal::chownToBuilder(const Path & path) +{ + if (!buildUser) return; + if (chown(path.c_str(), buildUser->getUID(), buildUser->getGID()) == -1) + throw SysError("cannot change ownership of '%1%'", path); +} + + +void setupSeccomp() +{ +#if __linux__ + if (!settings.filterSyscalls) return; +#if HAVE_SECCOMP + scmp_filter_ctx ctx; + + if (!(ctx = seccomp_init(SCMP_ACT_ALLOW))) + throw SysError("unable to initialize seccomp mode 2"); + + Finally cleanup([&]() { + seccomp_release(ctx); + }); + + if (nativeSystem == "x86_64-linux" && + seccomp_arch_add(ctx, SCMP_ARCH_X86) != 0) + throw SysError("unable to add 32-bit seccomp architecture"); + + if (nativeSystem == "x86_64-linux" && + seccomp_arch_add(ctx, SCMP_ARCH_X32) != 0) + throw SysError("unable to add X32 seccomp architecture"); + + if (nativeSystem == "aarch64-linux" && + seccomp_arch_add(ctx, SCMP_ARCH_ARM) != 0) + printError("unable to add ARM seccomp architecture; this may result in spurious build failures if running 32-bit ARM processes"); + + /* Prevent builders from creating setuid/setgid binaries. */ + for (int perm : { S_ISUID, S_ISGID }) { + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(chmod), 1, + SCMP_A1(SCMP_CMP_MASKED_EQ, (scmp_datum_t) perm, (scmp_datum_t) perm)) != 0) + throw SysError("unable to add seccomp rule"); + + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(fchmod), 1, + SCMP_A1(SCMP_CMP_MASKED_EQ, (scmp_datum_t) perm, (scmp_datum_t) perm)) != 0) + throw SysError("unable to add seccomp rule"); + + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(fchmodat), 1, + SCMP_A2(SCMP_CMP_MASKED_EQ, (scmp_datum_t) perm, (scmp_datum_t) perm)) != 0) + throw SysError("unable to add seccomp rule"); + } + + /* Prevent builders from creating EAs or ACLs. Not all filesystems + support these, and they're not allowed in the Nix store because + they're not representable in the NAR serialisation. */ + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(setxattr), 0) != 0 || + seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(lsetxattr), 0) != 0 || + seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(fsetxattr), 0) != 0) + throw SysError("unable to add seccomp rule"); + + if (seccomp_attr_set(ctx, SCMP_FLTATR_CTL_NNP, settings.allowNewPrivileges ? 0 : 1) != 0) + throw SysError("unable to set 'no new privileges' seccomp attribute"); + + if (seccomp_load(ctx) != 0) + throw SysError("unable to load seccomp BPF program"); +#else + throw Error( + "seccomp is not supported on this platform; " + "you can bypass this error by setting the option 'filter-syscalls' to false, but note that untrusted builds can then create setuid binaries!"); +#endif +#endif +} + + +void LocalDerivationGoal::runChild() +{ + /* Warning: in the child we should absolutely not make any SQLite + calls! */ + + try { /* child */ + + commonChildInit(builderOut); + + try { + setupSeccomp(); + } catch (...) { + if (buildUser) throw; + } + + bool setUser = true; + + /* Make the contents of netrc available to builtin:fetchurl + (which may run under a different uid and/or in a sandbox). */ + std::string netrcData; + try { + if (drv->isBuiltin() && drv->builder == "builtin:fetchurl") + netrcData = readFile(settings.netrcFile); + } catch (SysError &) { } + +#if __linux__ + if (useChroot) { + + userNamespaceSync.writeSide = -1; + + if (drainFD(userNamespaceSync.readSide.get()) != "1") + throw Error("user namespace initialisation failed"); + + userNamespaceSync.readSide = -1; + + if (privateNetwork) { + + /* Initialise the loopback interface. */ + AutoCloseFD fd(socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)); + if (!fd) throw SysError("cannot open IP socket"); + + struct ifreq ifr; + strcpy(ifr.ifr_name, "lo"); + ifr.ifr_flags = IFF_UP | IFF_LOOPBACK | IFF_RUNNING; + if (ioctl(fd.get(), SIOCSIFFLAGS, &ifr) == -1) + throw SysError("cannot set loopback interface flags"); + } + + /* Set the hostname etc. to fixed values. */ + char hostname[] = "localhost"; + if (sethostname(hostname, sizeof(hostname)) == -1) + throw SysError("cannot set host name"); + char domainname[] = "(none)"; // kernel default + if (setdomainname(domainname, sizeof(domainname)) == -1) + throw SysError("cannot set domain name"); + + /* Make all filesystems private. This is necessary + because subtrees may have been mounted as "shared" + (MS_SHARED). (Systemd does this, for instance.) Even + though we have a private mount namespace, mounting + filesystems on top of a shared subtree still propagates + outside of the namespace. Making a subtree private is + local to the namespace, though, so setting MS_PRIVATE + does not affect the outside world. */ + if (mount(0, "/", 0, MS_PRIVATE | MS_REC, 0) == -1) + throw SysError("unable to make '/' private"); + + /* Bind-mount chroot directory to itself, to treat it as a + different filesystem from /, as needed for pivot_root. */ + if (mount(chrootRootDir.c_str(), chrootRootDir.c_str(), 0, MS_BIND, 0) == -1) + throw SysError("unable to bind mount '%1%'", chrootRootDir); + + /* Bind-mount the sandbox's Nix store onto itself so that + we can mark it as a "shared" subtree, allowing bind + mounts made in *this* mount namespace to be propagated + into the child namespace created by the + unshare(CLONE_NEWNS) call below. + + Marking chrootRootDir as MS_SHARED causes pivot_root() + to fail with EINVAL. Don't know why. */ + Path chrootStoreDir = chrootRootDir + worker.store.storeDir; + + if (mount(chrootStoreDir.c_str(), chrootStoreDir.c_str(), 0, MS_BIND, 0) == -1) + throw SysError("unable to bind mount the Nix store", chrootStoreDir); + + if (mount(0, chrootStoreDir.c_str(), 0, MS_SHARED, 0) == -1) + throw SysError("unable to make '%s' shared", chrootStoreDir); + + /* Set up a nearly empty /dev, unless the user asked to + bind-mount the host /dev. */ + Strings ss; + if (dirsInChroot.find("/dev") == dirsInChroot.end()) { + createDirs(chrootRootDir + "/dev/shm"); + createDirs(chrootRootDir + "/dev/pts"); + ss.push_back("/dev/full"); + if (worker.store.systemFeatures.get().count("kvm") && pathExists("/dev/kvm")) + ss.push_back("/dev/kvm"); + ss.push_back("/dev/null"); + ss.push_back("/dev/random"); + ss.push_back("/dev/tty"); + ss.push_back("/dev/urandom"); + ss.push_back("/dev/zero"); + createSymlink("/proc/self/fd", chrootRootDir + "/dev/fd"); + createSymlink("/proc/self/fd/0", chrootRootDir + "/dev/stdin"); + createSymlink("/proc/self/fd/1", chrootRootDir + "/dev/stdout"); + createSymlink("/proc/self/fd/2", chrootRootDir + "/dev/stderr"); + } + + /* Fixed-output derivations typically need to access the + network, so give them access to /etc/resolv.conf and so + on. */ + if (derivationIsImpure(derivationType)) { + // Only use nss functions to resolve hosts and + // services. Don’t use it for anything else that may + // be configured for this system. This limits the + // potential impurities introduced in fixed-outputs. + writeFile(chrootRootDir + "/etc/nsswitch.conf", "hosts: files dns\nservices: files\n"); + + /* N.B. it is realistic that these paths might not exist. It + happens when testing Nix building fixed-output derivations + within a pure derivation. */ + for (auto & path : { "/etc/resolv.conf", "/etc/services", "/etc/hosts" }) + if (pathExists(path)) + ss.push_back(path); + } + + for (auto & i : ss) dirsInChroot.emplace(i, i); + + /* Bind-mount all the directories from the "host" + filesystem that we want in the chroot + environment. */ + auto doBind = [&](const Path & source, const Path & target, bool optional = false) { + debug("bind mounting '%1%' to '%2%'", source, target); + struct stat st; + if (stat(source.c_str(), &st) == -1) { + if (optional && errno == ENOENT) + return; + else + throw SysError("getting attributes of path '%1%'", source); + } + if (S_ISDIR(st.st_mode)) + createDirs(target); + else { + createDirs(dirOf(target)); + writeFile(target, ""); + } + if (mount(source.c_str(), target.c_str(), "", MS_BIND | MS_REC, 0) == -1) + throw SysError("bind mount from '%1%' to '%2%' failed", source, target); + }; + + for (auto & i : dirsInChroot) { + if (i.second.source == "/proc") continue; // backwards compatibility + doBind(i.second.source, chrootRootDir + i.first, i.second.optional); + } + + /* Bind a new instance of procfs on /proc. */ + createDirs(chrootRootDir + "/proc"); + if (mount("none", (chrootRootDir + "/proc").c_str(), "proc", 0, 0) == -1) + throw SysError("mounting /proc"); + + /* Mount sysfs on /sys. */ + if (useUidRange) { + createDirs(chrootRootDir + "/sys"); + if (mount("none", (chrootRootDir + "/sys").c_str(), "sysfs", 0, 0) == -1) + throw SysError("mounting /sys"); + } + + /* Mount a new tmpfs on /dev/shm to ensure that whatever + the builder puts in /dev/shm is cleaned up automatically. */ + if (pathExists("/dev/shm") && mount("none", (chrootRootDir + "/dev/shm").c_str(), "tmpfs", 0, + fmt("size=%s", settings.sandboxShmSize).c_str()) == -1) + throw SysError("mounting /dev/shm"); + + /* Mount a new devpts on /dev/pts. Note that this + requires the kernel to be compiled with + CONFIG_DEVPTS_MULTIPLE_INSTANCES=y (which is the case + if /dev/ptx/ptmx exists). */ + if (pathExists("/dev/pts/ptmx") && + !pathExists(chrootRootDir + "/dev/ptmx") + && !dirsInChroot.count("/dev/pts")) + { + if (mount("none", (chrootRootDir + "/dev/pts").c_str(), "devpts", 0, "newinstance,mode=0620") == 0) + { + createSymlink("/dev/pts/ptmx", chrootRootDir + "/dev/ptmx"); + + /* Make sure /dev/pts/ptmx is world-writable. With some + Linux versions, it is created with permissions 0. */ + chmod_(chrootRootDir + "/dev/pts/ptmx", 0666); + } else { + if (errno != EINVAL) + throw SysError("mounting /dev/pts"); + doBind("/dev/pts", chrootRootDir + "/dev/pts"); + doBind("/dev/ptmx", chrootRootDir + "/dev/ptmx"); + } + } + + /* Unshare this mount namespace. This is necessary because + pivot_root() below changes the root of the mount + namespace. This means that the call to setns() in + addDependency() would hide the host's filesystem, + making it impossible to bind-mount paths from the host + Nix store into the sandbox. Therefore, we save the + pre-pivot_root namespace in + sandboxMountNamespace. Since we made /nix/store a + shared subtree above, this allows addDependency() to + make paths appear in the sandbox. */ + if (unshare(CLONE_NEWNS) == -1) + throw SysError("unsharing mount namespace"); + + /* Unshare the cgroup namespace. This means + /proc/self/cgroup will show the child's cgroup as '/' + rather than whatever it is in the parent. */ + if (useSystemdCgroup && unshare(CLONE_NEWCGROUP) == -1) + throw SysError("unsharing cgroup namespace"); + + /* Do the chroot(). */ + if (chdir(chrootRootDir.c_str()) == -1) + throw SysError("cannot change directory to '%1%'", chrootRootDir); + + if (mkdir("real-root", 0) == -1) + throw SysError("cannot create real-root directory"); + + if (pivot_root(".", "real-root") == -1) + throw SysError("cannot pivot old root directory onto '%1%'", (chrootRootDir + "/real-root")); + + if (chroot(".") == -1) + throw SysError("cannot change root directory to '%1%'", chrootRootDir); + + if (umount2("real-root", MNT_DETACH) == -1) + throw SysError("cannot unmount real root filesystem"); + + if (rmdir("real-root") == -1) + throw SysError("cannot remove real-root directory"); + + /* Switch to the sandbox uid/gid in the user namespace, + which corresponds to the build user or calling user in + the parent namespace. */ + if (setgid(sandboxGid()) == -1) + throw SysError("setgid failed"); + if (setuid(sandboxUid()) == -1) + throw SysError("setuid failed"); + + setUser = false; + } +#endif + + if (chdir(tmpDirInSandbox.c_str()) == -1) + throw SysError("changing into '%1%'", tmpDir); + + /* Close all other file descriptors. */ + closeMostFDs({STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO}); + +#if __linux__ + /* Change the personality to 32-bit if we're doing an + i686-linux build on an x86_64-linux machine. */ + struct utsname utsbuf; + uname(&utsbuf); + if (drv->platform == "i686-linux" && + (settings.thisSystem == "x86_64-linux" || + (!strcmp(utsbuf.sysname, "Linux") && !strcmp(utsbuf.machine, "x86_64")))) { + if (personality(PER_LINUX32) == -1) + throw SysError("cannot set i686-linux personality"); + } + + /* Impersonate a Linux 2.6 machine to get some determinism in + builds that depend on the kernel version. */ + if ((drv->platform == "i686-linux" || drv->platform == "x86_64-linux") && settings.impersonateLinux26) { + int cur = personality(0xffffffff); + if (cur != -1) personality(cur | 0x0020000 /* == UNAME26 */); + } + + /* Disable address space randomization for improved + determinism. */ + int cur = personality(0xffffffff); + if (cur != -1) personality(cur | ADDR_NO_RANDOMIZE); +#endif + + /* Disable core dumps by default. */ + struct rlimit limit = { 0, RLIM_INFINITY }; + setrlimit(RLIMIT_CORE, &limit); + + // FIXME: set other limits to deterministic values? + + /* Fill in the environment. */ + Strings envStrs; + for (auto & i : env) + envStrs.push_back(rewriteStrings(i.first + "=" + i.second, inputRewrites)); + + /* If we are running in `build-users' mode, then switch to the + user we allocated above. Make sure that we drop all root + privileges. Note that above we have closed all file + descriptors except std*, so that's safe. Also note that + setuid() when run as root sets the real, effective and + saved UIDs. */ + if (setUser && buildUser) { + /* Preserve supplementary groups of the build user, to allow + admins to specify groups such as "kvm". */ + if (!buildUser->getSupplementaryGIDs().empty() && + setgroups(buildUser->getSupplementaryGIDs().size(), + buildUser->getSupplementaryGIDs().data()) == -1) + throw SysError("cannot set supplementary groups of build user"); + + if (setgid(buildUser->getGID()) == -1 || + getgid() != buildUser->getGID() || + getegid() != buildUser->getGID()) + throw SysError("setgid failed"); + + if (setuid(buildUser->getUID()) == -1 || + getuid() != buildUser->getUID() || + geteuid() != buildUser->getUID()) + throw SysError("setuid failed"); + } + + /* Fill in the arguments. */ + Strings args; + + const char *builder = "invalid"; + + if (drv->isBuiltin()) { + ; + } +#if __APPLE__ + else { + /* This has to appear before import statements. */ + std::string sandboxProfile = "(version 1)\n"; + + if (useChroot) { + + /* Lots and lots and lots of file functions freak out if they can't stat their full ancestry */ + PathSet ancestry; + + /* We build the ancestry before adding all inputPaths to the store because we know they'll + all have the same parents (the store), and there might be lots of inputs. This isn't + particularly efficient... I doubt it'll be a bottleneck in practice */ + for (auto & i : dirsInChroot) { + Path cur = i.first; + while (cur.compare("/") != 0) { + cur = dirOf(cur); + ancestry.insert(cur); + } + } + + /* And we want the store in there regardless of how empty dirsInChroot. We include the innermost + path component this time, since it's typically /nix/store and we care about that. */ + Path cur = worker.store.storeDir; + while (cur.compare("/") != 0) { + ancestry.insert(cur); + cur = dirOf(cur); + } + + /* Add all our input paths to the chroot */ + for (auto & i : inputPaths) { + auto p = worker.store.printStorePath(i); + dirsInChroot[p] = p; + } + + /* Violations will go to the syslog if you set this. Unfortunately the destination does not appear to be configurable */ + if (settings.darwinLogSandboxViolations) { + sandboxProfile += "(deny default)\n"; + } else { + sandboxProfile += "(deny default (with no-log))\n"; + } + + sandboxProfile += "(import \"sandbox-defaults.sb\")\n"; + + if (derivationIsImpure(derivationType)) + sandboxProfile += "(import \"sandbox-network.sb\")\n"; + + /* Add the output paths we'll use at build-time to the chroot */ + sandboxProfile += "(allow file-read* file-write* process-exec\n"; + for (auto & [_, path] : scratchOutputs) + sandboxProfile += fmt("\t(subpath \"%s\")\n", worker.store.printStorePath(path)); + + sandboxProfile += ")\n"; + + /* Our inputs (transitive dependencies and any impurities computed above) + + without file-write* allowed, access() incorrectly returns EPERM + */ + sandboxProfile += "(allow file-read* file-write* process-exec\n"; + for (auto & i : dirsInChroot) { + if (i.first != i.second.source) + throw Error( + "can't map '%1%' to '%2%': mismatched impure paths not supported on Darwin", + i.first, i.second.source); + + string path = i.first; + struct stat st; + if (lstat(path.c_str(), &st)) { + if (i.second.optional && errno == ENOENT) + continue; + throw SysError("getting attributes of path '%s", path); + } + if (S_ISDIR(st.st_mode)) + sandboxProfile += fmt("\t(subpath \"%s\")\n", path); + else + sandboxProfile += fmt("\t(literal \"%s\")\n", path); + } + sandboxProfile += ")\n"; + + /* Allow file-read* on full directory hierarchy to self. Allows realpath() */ + sandboxProfile += "(allow file-read*\n"; + for (auto & i : ancestry) { + sandboxProfile += fmt("\t(literal \"%s\")\n", i); + } + sandboxProfile += ")\n"; + + sandboxProfile += additionalSandboxProfile; + } else + sandboxProfile += "(import \"sandbox-minimal.sb\")\n"; + + debug("Generated sandbox profile:"); + debug(sandboxProfile); + + Path sandboxFile = tmpDir + "/.sandbox.sb"; + + writeFile(sandboxFile, sandboxProfile); + + bool allowLocalNetworking = parsedDrv->getBoolAttr("__darwinAllowLocalNetworking"); + + /* The tmpDir in scope points at the temporary build directory for our derivation. Some packages try different mechanisms + to find temporary directories, so we want to open up a broader place for them to dump their files, if needed. */ + Path globalTmpDir = canonPath(getEnv("TMPDIR").value_or("/tmp"), true); + + /* They don't like trailing slashes on subpath directives */ + if (globalTmpDir.back() == '/') globalTmpDir.pop_back(); + + if (getEnv("_NIX_TEST_NO_SANDBOX") != "1") { + builder = "/usr/bin/sandbox-exec"; + args.push_back("sandbox-exec"); + args.push_back("-f"); + args.push_back(sandboxFile); + args.push_back("-D"); + args.push_back("_GLOBAL_TMP_DIR=" + globalTmpDir); + args.push_back("-D"); + args.push_back("IMPORT_DIR=" + settings.nixDataDir + "/nix/sandbox/"); + if (allowLocalNetworking) { + args.push_back("-D"); + args.push_back(string("_ALLOW_LOCAL_NETWORKING=1")); + } + args.push_back(drv->builder); + } else { + builder = drv->builder.c_str(); + args.push_back(std::string(baseNameOf(drv->builder))); + } + } +#else + else { + builder = drv->builder.c_str(); + args.push_back(std::string(baseNameOf(drv->builder))); + } +#endif + + for (auto & i : drv->args) + args.push_back(rewriteStrings(i, inputRewrites)); + + /* Indicate that we managed to set up the build environment. */ + writeFull(STDERR_FILENO, string("\2\n")); + + /* Execute the program. This should not return. */ + if (drv->isBuiltin()) { + try { + logger = makeJSONLogger(*logger); + + BasicDerivation & drv2(*drv); + for (auto & e : drv2.env) + e.second = rewriteStrings(e.second, inputRewrites); + + if (drv->builder == "builtin:fetchurl") + builtinFetchurl(drv2, netrcData); + else if (drv->builder == "builtin:buildenv") + builtinBuildenv(drv2); + else if (drv->builder == "builtin:unpack-channel") + builtinUnpackChannel(drv2); + else + throw Error("unsupported builtin function '%1%'", string(drv->builder, 8)); + _exit(0); + } catch (std::exception & e) { + writeFull(STDERR_FILENO, e.what() + std::string("\n")); + _exit(1); + } + } + +#if __APPLE__ + posix_spawnattr_t attrp; + + if (posix_spawnattr_init(&attrp)) + throw SysError("failed to initialize builder"); + + if (posix_spawnattr_setflags(&attrp, POSIX_SPAWN_SETEXEC)) + throw SysError("failed to initialize builder"); + + if (drv->platform == "aarch64-darwin") { + // Unset kern.curproc_arch_affinity so we can escape Rosetta + int affinity = 0; + sysctlbyname("kern.curproc_arch_affinity", NULL, NULL, &affinity, sizeof(affinity)); + + cpu_type_t cpu = CPU_TYPE_ARM64; + posix_spawnattr_setbinpref_np(&attrp, 1, &cpu, NULL); + } else if (drv->platform == "x86_64-darwin") { + cpu_type_t cpu = CPU_TYPE_X86_64; + posix_spawnattr_setbinpref_np(&attrp, 1, &cpu, NULL); + } + + posix_spawn(NULL, builder, NULL, &attrp, stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data()); +#else + execve(builder, stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data()); +#endif + + throw SysError("executing '%1%'", drv->builder); + + } catch (Error & e) { + writeFull(STDERR_FILENO, "\1\n"); + FdSink sink(STDERR_FILENO); + sink << e; + sink.flush(); + _exit(1); + } +} + + +void LocalDerivationGoal::registerOutputs() +{ + /* When using a build hook, the build hook can register the output + as valid (by doing `nix-store --import'). If so we don't have + to do anything here. + + We can only early return when the outputs are known a priori. For + floating content-addressed derivations this isn't the case. + */ + if (hook) { + DerivationGoal::registerOutputs(); + return; + } + + std::map<std::string, ValidPathInfo> infos; + + /* Set of inodes seen during calls to canonicalisePathMetaData() + for this build's outputs. This needs to be shared between + outputs to allow hard links between outputs. */ + InodesSeen inodesSeen; + + Path checkSuffix = ".check"; + bool keepPreviousRound = settings.keepFailed || settings.runDiffHook; + + std::exception_ptr delayedException; + + /* The paths that can be referenced are the input closures, the + output paths, and any paths that have been built via recursive + Nix calls. */ + StorePathSet referenceablePaths; + for (auto & p : inputPaths) referenceablePaths.insert(p); + for (auto & i : scratchOutputs) referenceablePaths.insert(i.second); + for (auto & p : addedPaths) referenceablePaths.insert(p); + + /* FIXME `needsHashRewrite` should probably be removed and we get to the + real reason why we aren't using the chroot dir */ + auto toRealPathChroot = [&](const Path & p) -> Path { + return useChroot && !needsHashRewrite() + ? chrootRootDir + p + : worker.store.toRealPath(p); + }; + + /* Check whether the output paths were created, and make all + output paths read-only. Then get the references of each output (that we + might need to register), so we can topologically sort them. For the ones + that are most definitely already installed, we just store their final + name so we can also use it in rewrites. */ + StringSet outputsToSort; + struct AlreadyRegistered { StorePath path; }; + struct PerhapsNeedToRegister { StorePathSet refs; }; + std::map<std::string, std::variant<AlreadyRegistered, PerhapsNeedToRegister>> outputReferencesIfUnregistered; + std::map<std::string, struct stat> outputStats; + for (auto & [outputName, _] : drv->outputs) { + auto actualPath = toRealPathChroot(worker.store.printStorePath(scratchOutputs.at(outputName))); + + outputsToSort.insert(outputName); + + /* Updated wanted info to remove the outputs we definitely don't need to register */ + auto & initialInfo = initialOutputs.at(outputName); + + /* Don't register if already valid, and not checking */ + initialInfo.wanted = buildMode == bmCheck + || !(initialInfo.known && initialInfo.known->isValid()); + if (!initialInfo.wanted) { + outputReferencesIfUnregistered.insert_or_assign( + outputName, + AlreadyRegistered { .path = initialInfo.known->path }); + continue; + } + + struct stat st; + if (lstat(actualPath.c_str(), &st) == -1) { + if (errno == ENOENT) + throw BuildError( + "builder for '%s' failed to produce output path for output '%s' at '%s'", + worker.store.printStorePath(drvPath), outputName, actualPath); + throw SysError("getting attributes of path '%s'", actualPath); + } + +#ifndef __CYGWIN__ + /* Check that the output is not group or world writable, as + that means that someone else can have interfered with the + build. Also, the output should be owned by the build + user. */ + if ((!S_ISLNK(st.st_mode) && (st.st_mode & (S_IWGRP | S_IWOTH))) || + (buildUser && st.st_uid != buildUser->getUID())) + throw BuildError( + "suspicious ownership or permission on '%s' for output '%s'; rejecting this build output", + actualPath, outputName); +#endif + + /* Canonicalise first. This ensures that the path we're + rewriting doesn't contain a hard link to /etc/shadow or + something like that. */ + canonicalisePathMetaData( + actualPath, + buildUser ? std::optional(buildUser->getUIDRange()) : std::nullopt, + inodesSeen); + + debug("scanning for references for output '%s' in temp location '%s'", outputName, actualPath); + + /* Pass blank Sink as we are not ready to hash data at this stage. */ + NullSink blank; + auto references = worker.store.parseStorePathSet( + scanForReferences(blank, actualPath, worker.store.printStorePathSet(referenceablePaths))); + + outputReferencesIfUnregistered.insert_or_assign( + outputName, + PerhapsNeedToRegister { .refs = references }); + outputStats.insert_or_assign(outputName, std::move(st)); + } + + auto sortedOutputNames = topoSort(outputsToSort, + {[&](const std::string & name) { + return std::visit(overloaded { + /* Since we'll use the already installed versions of these, we + can treat them as leaves and ignore any references they + have. */ + [&](AlreadyRegistered _) { return StringSet {}; }, + [&](PerhapsNeedToRegister refs) { + StringSet referencedOutputs; + /* FIXME build inverted map up front so no quadratic waste here */ + for (auto & r : refs.refs) + for (auto & [o, p] : scratchOutputs) + if (r == p) + referencedOutputs.insert(o); + return referencedOutputs; + }, + }, outputReferencesIfUnregistered.at(name)); + }}, + {[&](const std::string & path, const std::string & parent) { + // TODO with more -vvvv also show the temporary paths for manual inspection. + return BuildError( + "cycle detected in build of '%s' in the references of output '%s' from output '%s'", + worker.store.printStorePath(drvPath), path, parent); + }}); + + std::reverse(sortedOutputNames.begin(), sortedOutputNames.end()); + + for (auto & outputName : sortedOutputNames) { + auto output = drv->outputs.at(outputName); + auto & scratchPath = scratchOutputs.at(outputName); + auto actualPath = toRealPathChroot(worker.store.printStorePath(scratchPath)); + + auto finish = [&](StorePath finalStorePath) { + /* Store the final path */ + finalOutputs.insert_or_assign(outputName, finalStorePath); + /* The rewrite rule will be used in downstream outputs that refer to + use. This is why the topological sort is essential to do first + before this for loop. */ + if (scratchPath != finalStorePath) + outputRewrites[std::string { scratchPath.hashPart() }] = std::string { finalStorePath.hashPart() }; + }; + + std::optional<StorePathSet> referencesOpt = std::visit(overloaded { + [&](AlreadyRegistered skippedFinalPath) -> std::optional<StorePathSet> { + finish(skippedFinalPath.path); + return std::nullopt; + }, + [&](PerhapsNeedToRegister r) -> std::optional<StorePathSet> { + return r.refs; + }, + }, outputReferencesIfUnregistered.at(outputName)); + + if (!referencesOpt) + continue; + auto references = *referencesOpt; + + auto rewriteOutput = [&]() { + /* Apply hash rewriting if necessary. */ + if (!outputRewrites.empty()) { + warn("rewriting hashes in '%1%'; cross fingers", actualPath); + + /* FIXME: this is in-memory. */ + StringSink sink; + dumpPath(actualPath, sink); + deletePath(actualPath); + sink.s = make_ref<std::string>(rewriteStrings(*sink.s, outputRewrites)); + StringSource source(*sink.s); + restorePath(actualPath, source); + + /* FIXME: set proper permissions in restorePath() so + we don't have to do another traversal. */ + canonicalisePathMetaData(actualPath, {}, inodesSeen); + } + }; + + auto rewriteRefs = [&]() -> std::pair<bool, StorePathSet> { + /* In the CA case, we need the rewritten refs to calculate the + final path, therefore we look for a *non-rewritten + self-reference, and use a bool rather try to solve the + computationally intractable fixed point. */ + std::pair<bool, StorePathSet> res { + false, + {}, + }; + for (auto & r : references) { + auto name = r.name(); + auto origHash = std::string { r.hashPart() }; + if (r == scratchPath) + res.first = true; + else if (outputRewrites.count(origHash) == 0) + res.second.insert(r); + else { + std::string newRef = outputRewrites.at(origHash); + newRef += '-'; + newRef += name; + res.second.insert(StorePath { newRef }); + } + } + return res; + }; + + auto newInfoFromCA = [&](const DerivationOutputCAFloating outputHash) -> ValidPathInfo { + auto & st = outputStats.at(outputName); + if (outputHash.method == FileIngestionMethod::Flat) { + /* The output path should be a regular file without execute permission. */ + if (!S_ISREG(st.st_mode) || (st.st_mode & S_IXUSR) != 0) + throw BuildError( + "output path '%1%' should be a non-executable regular file " + "since recursive hashing is not enabled (outputHashMode=flat)", + actualPath); + } + rewriteOutput(); + /* FIXME optimize and deduplicate with addToStore */ + std::string oldHashPart { scratchPath.hashPart() }; + HashModuloSink caSink { outputHash.hashType, oldHashPart }; + switch (outputHash.method) { + case FileIngestionMethod::Recursive: + dumpPath(actualPath, caSink); + break; + case FileIngestionMethod::Flat: + readFile(actualPath, caSink); + break; + } + auto got = caSink.finish().first; + auto refs = rewriteRefs(); + + auto finalPath = worker.store.makeFixedOutputPath( + outputHash.method, + got, + outputPathName(drv->name, outputName), + refs.second, + refs.first); + if (scratchPath != finalPath) { + // Also rewrite the output path + auto source = sinkToSource([&](Sink & nextSink) { + StringSink sink; + dumpPath(actualPath, sink); + RewritingSink rsink2(oldHashPart, std::string(finalPath.hashPart()), nextSink); + rsink2(*sink.s); + rsink2.flush(); + }); + Path tmpPath = actualPath + ".tmp"; + restorePath(tmpPath, *source); + deletePath(actualPath); + movePath(tmpPath, actualPath); + } + + HashResult narHashAndSize = hashPath(htSHA256, actualPath); + ValidPathInfo newInfo0 { + finalPath, + narHashAndSize.first, + }; + + newInfo0.narSize = narHashAndSize.second; + newInfo0.ca = FixedOutputHash { + .method = outputHash.method, + .hash = got, + }; + newInfo0.references = refs.second; + if (refs.first) + newInfo0.references.insert(newInfo0.path); + + assert(newInfo0.ca); + return newInfo0; + }; + + ValidPathInfo newInfo = std::visit(overloaded { + [&](DerivationOutputInputAddressed output) { + /* input-addressed case */ + auto requiredFinalPath = output.path; + /* Preemptively add rewrite rule for final hash, as that is + what the NAR hash will use rather than normalized-self references */ + if (scratchPath != requiredFinalPath) + outputRewrites.insert_or_assign( + std::string { scratchPath.hashPart() }, + std::string { requiredFinalPath.hashPart() }); + rewriteOutput(); + auto narHashAndSize = hashPath(htSHA256, actualPath); + ValidPathInfo newInfo0 { requiredFinalPath, narHashAndSize.first }; + newInfo0.narSize = narHashAndSize.second; + auto refs = rewriteRefs(); + newInfo0.references = refs.second; + if (refs.first) + newInfo0.references.insert(newInfo0.path); + return newInfo0; + }, + [&](DerivationOutputCAFixed dof) { + auto newInfo0 = newInfoFromCA(DerivationOutputCAFloating { + .method = dof.hash.method, + .hashType = dof.hash.hash.type, + }); + + /* Check wanted hash */ + Hash & wanted = dof.hash.hash; + assert(newInfo0.ca); + auto got = getContentAddressHash(*newInfo0.ca); + if (wanted != got) { + /* Throw an error after registering the path as + valid. */ + worker.hashMismatch = true; + delayedException = std::make_exception_ptr( + BuildError("hash mismatch in fixed-output derivation '%s':\n specified: %s\n got: %s", + worker.store.printStorePath(drvPath), + wanted.to_string(SRI, true), + got.to_string(SRI, true))); + } + return newInfo0; + }, + [&](DerivationOutputCAFloating dof) { + return newInfoFromCA(dof); + }, + [&](DerivationOutputDeferred) { + // No derivation should reach that point without having been + // rewritten first + assert(false); + // Ugly, but the compiler insists on having this return a value + // of type `ValidPathInfo` despite the `assert(false)`, so + // let's provide it + return *(ValidPathInfo*)0; + }, + }, output.output); + + /* FIXME: set proper permissions in restorePath() so + we don't have to do another traversal. */ + canonicalisePathMetaData(actualPath, {}, inodesSeen); + + /* Calculate where we'll move the output files. In the checking case we + will leave leave them where they are, for now, rather than move to + their usual "final destination" */ + auto finalDestPath = worker.store.printStorePath(newInfo.path); + + /* Lock final output path, if not already locked. This happens with + floating CA derivations and hash-mismatching fixed-output + derivations. */ + PathLocks dynamicOutputLock; + dynamicOutputLock.setDeletion(true); + auto optFixedPath = output.path(worker.store, drv->name, outputName); + if (!optFixedPath || + worker.store.printStorePath(*optFixedPath) != finalDestPath) + { + assert(newInfo.ca); + dynamicOutputLock.lockPaths({worker.store.toRealPath(finalDestPath)}); + } + + /* Move files, if needed */ + if (worker.store.toRealPath(finalDestPath) != actualPath) { + if (buildMode == bmRepair) { + /* Path already exists, need to replace it */ + replaceValidPath(worker.store.toRealPath(finalDestPath), actualPath); + actualPath = worker.store.toRealPath(finalDestPath); + } else if (buildMode == bmCheck) { + /* Path already exists, and we want to compare, so we leave out + new path in place. */ + } else if (worker.store.isValidPath(newInfo.path)) { + /* Path already exists because CA path produced by something + else. No moving needed. */ + assert(newInfo.ca); + } else { + auto destPath = worker.store.toRealPath(finalDestPath); + deletePath(destPath); + movePath(actualPath, destPath); + actualPath = destPath; + } + } + + auto & localStore = getLocalStore(); + + if (buildMode == bmCheck) { + + if (!worker.store.isValidPath(newInfo.path)) continue; + ValidPathInfo oldInfo(*worker.store.queryPathInfo(newInfo.path)); + if (newInfo.narHash != oldInfo.narHash) { + worker.checkMismatch = true; + if (settings.runDiffHook || settings.keepFailed) { + auto dst = worker.store.toRealPath(finalDestPath + checkSuffix); + deletePath(dst); + movePath(actualPath, dst); + + handleDiffHook( + buildUser ? buildUser->getUID() : getuid(), + buildUser ? buildUser->getGID() : getgid(), + finalDestPath, dst, worker.store.printStorePath(drvPath), tmpDir); + + throw NotDeterministic("derivation '%s' may not be deterministic: output '%s' differs from '%s'", + worker.store.printStorePath(drvPath), worker.store.toRealPath(finalDestPath), dst); + } else + throw NotDeterministic("derivation '%s' may not be deterministic: output '%s' differs", + worker.store.printStorePath(drvPath), worker.store.toRealPath(finalDestPath)); + } + + /* Since we verified the build, it's now ultimately trusted. */ + if (!oldInfo.ultimate) { + oldInfo.ultimate = true; + localStore.signPathInfo(oldInfo); + localStore.registerValidPaths({{oldInfo.path, oldInfo}}); + } + + continue; + } + + /* For debugging, print out the referenced and unreferenced paths. */ + for (auto & i : inputPaths) { + auto j = references.find(i); + if (j == references.end()) + debug("unreferenced input: '%1%'", worker.store.printStorePath(i)); + else + debug("referenced input: '%1%'", worker.store.printStorePath(i)); + } + + if (curRound == nrRounds) { + localStore.optimisePath(actualPath); // FIXME: combine with scanForReferences() + worker.markContentsGood(newInfo.path); + } + + newInfo.deriver = drvPath; + newInfo.ultimate = true; + localStore.signPathInfo(newInfo); + + finish(newInfo.path); + + /* If it's a CA path, register it right away. This is necessary if it + isn't statically known so that we can safely unlock the path before + the next iteration */ + if (newInfo.ca) + localStore.registerValidPaths({{newInfo.path, newInfo}}); + + infos.emplace(outputName, std::move(newInfo)); + } + + if (buildMode == bmCheck) return; + + /* Apply output checks. */ + checkOutputs(infos); + + /* Compare the result with the previous round, and report which + path is different, if any.*/ + if (curRound > 1 && prevInfos != infos) { + assert(prevInfos.size() == infos.size()); + for (auto i = prevInfos.begin(), j = infos.begin(); i != prevInfos.end(); ++i, ++j) + if (!(*i == *j)) { + result.isNonDeterministic = true; + Path prev = worker.store.printStorePath(i->second.path) + checkSuffix; + bool prevExists = keepPreviousRound && pathExists(prev); + hintformat hint = prevExists + ? hintfmt("output '%s' of '%s' differs from '%s' from previous round", + worker.store.printStorePath(i->second.path), worker.store.printStorePath(drvPath), prev) + : hintfmt("output '%s' of '%s' differs from previous round", + worker.store.printStorePath(i->second.path), worker.store.printStorePath(drvPath)); + + handleDiffHook( + buildUser ? buildUser->getUID() : getuid(), + buildUser ? buildUser->getGID() : getgid(), + prev, worker.store.printStorePath(i->second.path), + worker.store.printStorePath(drvPath), tmpDir); + + if (settings.enforceDeterminism) + throw NotDeterministic(hint); + + printError(hint); + + curRound = nrRounds; // we know enough, bail out early + } + } + + /* If this is the first round of several, then move the output out of the way. */ + if (nrRounds > 1 && curRound == 1 && curRound < nrRounds && keepPreviousRound) { + for (auto & [_, outputStorePath] : finalOutputs) { + auto path = worker.store.printStorePath(outputStorePath); + Path prev = path + checkSuffix; + deletePath(prev); + Path dst = path + checkSuffix; + if (rename(path.c_str(), dst.c_str())) + throw SysError("renaming '%s' to '%s'", path, dst); + } + } + + if (curRound < nrRounds) { + prevInfos = std::move(infos); + return; + } + + /* Remove the .check directories if we're done. FIXME: keep them + if the result was not determistic? */ + if (curRound == nrRounds) { + for (auto & [_, outputStorePath] : finalOutputs) { + Path prev = worker.store.printStorePath(outputStorePath) + checkSuffix; + deletePath(prev); + } + } + + /* Register each output path as valid, and register the sets of + paths referenced by each of them. If there are cycles in the + outputs, this will fail. */ + { + auto & localStore = getLocalStore(); + + ValidPathInfos infos2; + for (auto & [outputName, newInfo] : infos) { + infos2.insert_or_assign(newInfo.path, newInfo); + } + localStore.registerValidPaths(infos2); + } + + /* In case of a fixed-output derivation hash mismatch, throw an + exception now that we have registered the output as valid. */ + if (delayedException) + std::rethrow_exception(delayedException); + + /* If we made it this far, we are sure the output matches the derivation + (since the delayedException would be a fixed output CA mismatch). That + means it's safe to link the derivation to the output hash. We must do + that for floating CA derivations, which otherwise couldn't be cached, + but it's fine to do in all cases. */ + + if (settings.isExperimentalFeatureEnabled("ca-derivations")) { + for (auto& [outputName, newInfo] : infos) { + auto thisRealisation = Realisation{ + .id = DrvOutput{initialOutputs.at(outputName).outputHash, + outputName}, + .outPath = newInfo.path}; + signRealisation(thisRealisation); + worker.store.registerDrvOutput(thisRealisation); + } + } +} + +void LocalDerivationGoal::signRealisation(Realisation & realisation) +{ + getLocalStore().signRealisation(realisation); +} + + +void LocalDerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs) +{ + std::map<Path, const ValidPathInfo &> outputsByPath; + for (auto & output : outputs) + outputsByPath.emplace(worker.store.printStorePath(output.second.path), output.second); + + for (auto & output : outputs) { + auto & outputName = output.first; + auto & info = output.second; + + struct Checks + { + bool ignoreSelfRefs = false; + std::optional<uint64_t> maxSize, maxClosureSize; + std::optional<Strings> allowedReferences, allowedRequisites, disallowedReferences, disallowedRequisites; + }; + + /* Compute the closure and closure size of some output. This + is slightly tricky because some of its references (namely + other outputs) may not be valid yet. */ + auto getClosure = [&](const StorePath & path) + { + uint64_t closureSize = 0; + StorePathSet pathsDone; + std::queue<StorePath> pathsLeft; + pathsLeft.push(path); + + while (!pathsLeft.empty()) { + auto path = pathsLeft.front(); + pathsLeft.pop(); + if (!pathsDone.insert(path).second) continue; + + auto i = outputsByPath.find(worker.store.printStorePath(path)); + if (i != outputsByPath.end()) { + closureSize += i->second.narSize; + for (auto & ref : i->second.references) + pathsLeft.push(ref); + } else { + auto info = worker.store.queryPathInfo(path); + closureSize += info->narSize; + for (auto & ref : info->references) + pathsLeft.push(ref); + } + } + + return std::make_pair(std::move(pathsDone), closureSize); + }; + + auto applyChecks = [&](const Checks & checks) + { + if (checks.maxSize && info.narSize > *checks.maxSize) + throw BuildError("path '%s' is too large at %d bytes; limit is %d bytes", + worker.store.printStorePath(info.path), info.narSize, *checks.maxSize); + + if (checks.maxClosureSize) { + uint64_t closureSize = getClosure(info.path).second; + if (closureSize > *checks.maxClosureSize) + throw BuildError("closure of path '%s' is too large at %d bytes; limit is %d bytes", + worker.store.printStorePath(info.path), closureSize, *checks.maxClosureSize); + } + + auto checkRefs = [&](const std::optional<Strings> & value, bool allowed, bool recursive) + { + if (!value) return; + + /* Parse a list of reference specifiers. Each element must + either be a store path, or the symbolic name of the output + of the derivation (such as `out'). */ + StorePathSet spec; + for (auto & i : *value) { + if (worker.store.isStorePath(i)) + spec.insert(worker.store.parseStorePath(i)); + else if (finalOutputs.count(i)) + spec.insert(finalOutputs.at(i)); + else throw BuildError("derivation contains an illegal reference specifier '%s'", i); + } + + auto used = recursive + ? getClosure(info.path).first + : info.references; + + if (recursive && checks.ignoreSelfRefs) + used.erase(info.path); + + StorePathSet badPaths; + + for (auto & i : used) + if (allowed) { + if (!spec.count(i)) + badPaths.insert(i); + } else { + if (spec.count(i)) + badPaths.insert(i); + } + + if (!badPaths.empty()) { + string badPathsStr; + for (auto & i : badPaths) { + badPathsStr += "\n "; + badPathsStr += worker.store.printStorePath(i); + } + throw BuildError("output '%s' is not allowed to refer to the following paths:%s", + worker.store.printStorePath(info.path), badPathsStr); + } + }; + + checkRefs(checks.allowedReferences, true, false); + checkRefs(checks.allowedRequisites, true, true); + checkRefs(checks.disallowedReferences, false, false); + checkRefs(checks.disallowedRequisites, false, true); + }; + + if (auto structuredAttrs = parsedDrv->getStructuredAttrs()) { + auto outputChecks = structuredAttrs->find("outputChecks"); + if (outputChecks != structuredAttrs->end()) { + auto output = outputChecks->find(outputName); + + if (output != outputChecks->end()) { + Checks checks; + + auto maxSize = output->find("maxSize"); + if (maxSize != output->end()) + checks.maxSize = maxSize->get<uint64_t>(); + + auto maxClosureSize = output->find("maxClosureSize"); + if (maxClosureSize != output->end()) + checks.maxClosureSize = maxClosureSize->get<uint64_t>(); + + auto get = [&](const std::string & name) -> std::optional<Strings> { + auto i = output->find(name); + if (i != output->end()) { + Strings res; + for (auto j = i->begin(); j != i->end(); ++j) { + if (!j->is_string()) + throw Error("attribute '%s' of derivation '%s' must be a list of strings", name, worker.store.printStorePath(drvPath)); + res.push_back(j->get<std::string>()); + } + checks.disallowedRequisites = res; + return res; + } + return {}; + }; + + checks.allowedReferences = get("allowedReferences"); + checks.allowedRequisites = get("allowedRequisites"); + checks.disallowedReferences = get("disallowedReferences"); + checks.disallowedRequisites = get("disallowedRequisites"); + + applyChecks(checks); + } + } + } else { + // legacy non-structured-attributes case + Checks checks; + checks.ignoreSelfRefs = true; + checks.allowedReferences = parsedDrv->getStringsAttr("allowedReferences"); + checks.allowedRequisites = parsedDrv->getStringsAttr("allowedRequisites"); + checks.disallowedReferences = parsedDrv->getStringsAttr("disallowedReferences"); + checks.disallowedRequisites = parsedDrv->getStringsAttr("disallowedRequisites"); + applyChecks(checks); + } + } +} + + +void LocalDerivationGoal::deleteTmpDir(bool force) +{ + if (tmpDir != "") { + /* Don't keep temporary directories for builtins because they + might have privileged stuff (like a copy of netrc). */ + if (settings.keepFailed && !force && !drv->isBuiltin()) { + printError("note: keeping build directory '%s'", tmpDir); + chmod(tmpDir.c_str(), 0755); + } + else + deletePath(tmpDir); + tmpDir = ""; + } +} + + +bool LocalDerivationGoal::isReadDesc(int fd) +{ + return (hook && DerivationGoal::isReadDesc(fd)) || + (!hook && fd == builderOut.readSide.get()); +} + + +StorePath LocalDerivationGoal::makeFallbackPath(std::string_view outputName) +{ + return worker.store.makeStorePath( + "rewrite:" + std::string(drvPath.to_string()) + ":name:" + std::string(outputName), + Hash(htSHA256), outputPathName(drv->name, outputName)); +} + + +StorePath LocalDerivationGoal::makeFallbackPath(const StorePath & path) +{ + return worker.store.makeStorePath( + "rewrite:" + std::string(drvPath.to_string()) + ":" + std::string(path.to_string()), + Hash(htSHA256), path.name()); +} + + +} |