lix/src/libstore/daemon.cc

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#include "daemon.hh"
#include "monitor-fd.hh"
#include "worker-protocol.hh"
#include "store-api.hh"
#include "local-store.hh"
#include "finally.hh"
#include "affinity.hh"
#include "archive.hh"
#include "derivations.hh"
#include "args.hh"
namespace nix::daemon {
Sink & operator << (Sink & sink, const Logger::Fields & fields)
{
sink << fields.size();
for (auto & f : fields) {
sink << f.type;
if (f.type == Logger::Field::tInt)
sink << f.i;
else if (f.type == Logger::Field::tString)
sink << f.s;
else abort();
}
return sink;
}
/* Logger that forwards log messages to the client, *if* we're in a
state where the protocol allows it (i.e., when canSendStderr is
true). */
struct TunnelLogger : public Logger
{
FdSink & to;
struct State
{
bool canSendStderr = false;
std::vector<std::string> pendingMsgs;
};
Sync<State> state_;
unsigned int clientVersion;
TunnelLogger(FdSink & to, unsigned int clientVersion)
: to(to), clientVersion(clientVersion) { }
void enqueueMsg(const std::string & s)
{
auto state(state_.lock());
if (state->canSendStderr) {
assert(state->pendingMsgs.empty());
try {
to(s);
to.flush();
} catch (...) {
/* Write failed; that means that the other side is
gone. */
state->canSendStderr = false;
throw;
}
} else
state->pendingMsgs.push_back(s);
}
void log(Verbosity lvl, const FormatOrString & fs) override
{
if (lvl > verbosity) return;
StringSink buf;
buf << STDERR_NEXT << (fs.s + "\n");
enqueueMsg(*buf.s);
}
void logEI(const ErrorInfo & ei) override
{
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if (ei.level > verbosity) return;
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std::stringstream oss;
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oss << ei;
StringSink buf;
buf << STDERR_NEXT << oss.str() << "\n"; // (fs.s + "\n");
enqueueMsg(*buf.s);
}
/* startWork() means that we're starting an operation for which we
want to send out stderr to the client. */
void startWork()
{
auto state(state_.lock());
state->canSendStderr = true;
for (auto & msg : state->pendingMsgs)
to(msg);
state->pendingMsgs.clear();
to.flush();
}
/* stopWork() means that we're done; stop sending stderr to the
client. */
void stopWork(bool success = true, const string & msg = "", unsigned int status = 0)
{
auto state(state_.lock());
state->canSendStderr = false;
if (success)
to << STDERR_LAST;
else {
to << STDERR_ERROR << msg;
if (status != 0) to << status;
}
}
void startActivity(ActivityId act, Verbosity lvl, ActivityType type,
const std::string & s, const Fields & fields, ActivityId parent) override
{
if (GET_PROTOCOL_MINOR(clientVersion) < 20) {
if (!s.empty())
log(lvl, s + "...");
return;
}
StringSink buf;
buf << STDERR_START_ACTIVITY << act << lvl << type << s << fields << parent;
enqueueMsg(*buf.s);
}
void stopActivity(ActivityId act) override
{
if (GET_PROTOCOL_MINOR(clientVersion) < 20) return;
StringSink buf;
buf << STDERR_STOP_ACTIVITY << act;
enqueueMsg(*buf.s);
}
void result(ActivityId act, ResultType type, const Fields & fields) override
{
if (GET_PROTOCOL_MINOR(clientVersion) < 20) return;
StringSink buf;
buf << STDERR_RESULT << act << type << fields;
enqueueMsg(*buf.s);
}
};
struct TunnelSink : Sink
{
Sink & to;
TunnelSink(Sink & to) : to(to) { }
virtual void operator () (const unsigned char * data, size_t len)
{
to << STDERR_WRITE;
writeString(data, len, to);
}
};
struct TunnelSource : BufferedSource
{
Source & from;
BufferedSink & to;
TunnelSource(Source & from, BufferedSink & to) : from(from), to(to) { }
size_t readUnbuffered(unsigned char * data, size_t len) override
{
to << STDERR_READ << len;
to.flush();
size_t n = readString(data, len, from);
if (n == 0) throw EndOfFile("unexpected end-of-file");
return n;
}
};
/* If the NAR archive contains a single file at top-level, then save
the contents of the file to `s'. Otherwise barf. */
struct RetrieveRegularNARSink : ParseSink
{
bool regular;
string s;
RetrieveRegularNARSink() : regular(true) { }
void createDirectory(const Path & path)
{
regular = false;
}
void receiveContents(unsigned char * data, unsigned int len)
{
s.append((const char *) data, len);
}
void createSymlink(const Path & path, const string & target)
{
regular = false;
}
};
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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struct ClientSettings
{
bool keepFailed;
bool keepGoing;
bool tryFallback;
Verbosity verbosity;
unsigned int maxBuildJobs;
time_t maxSilentTime;
bool verboseBuild;
unsigned int buildCores;
bool useSubstitutes;
StringMap overrides;
void apply(TrustedFlag trusted)
{
settings.keepFailed = keepFailed;
settings.keepGoing = keepGoing;
settings.tryFallback = tryFallback;
nix::verbosity = verbosity;
settings.maxBuildJobs.assign(maxBuildJobs);
settings.maxSilentTime = maxSilentTime;
settings.verboseBuild = verboseBuild;
settings.buildCores = buildCores;
settings.useSubstitutes = useSubstitutes;
for (auto & i : overrides) {
auto & name(i.first);
auto & value(i.second);
auto setSubstituters = [&](Setting<Strings> & res) {
if (name != res.name && res.aliases.count(name) == 0)
return false;
StringSet trusted = settings.trustedSubstituters;
for (auto & s : settings.substituters.get())
trusted.insert(s);
Strings subs;
auto ss = tokenizeString<Strings>(value);
for (auto & s : ss)
if (trusted.count(s))
subs.push_back(s);
else
warn("ignoring untrusted substituter '%s'", s);
res = subs;
return true;
};
try {
if (name == "ssh-auth-sock") // obsolete
;
else if (trusted
|| name == settings.buildTimeout.name
|| name == "connect-timeout"
|| (name == "builders" && value == ""))
settings.set(name, value);
else if (setSubstituters(settings.substituters))
;
else if (setSubstituters(settings.extraSubstituters))
;
else
warn("ignoring the user-specified setting '%s', because it is a restricted setting and you are not a trusted user", name);
} catch (UsageError & e) {
warn(e.what());
}
}
}
};
static void performOp(TunnelLogger * logger, ref<Store> store,
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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TrustedFlag trusted, RecursiveFlag recursive, unsigned int clientVersion,
Source & from, BufferedSink & to, unsigned int op)
{
switch (op) {
case wopIsValidPath: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
bool result = store->isValidPath(path);
logger->stopWork();
to << result;
break;
}
case wopQueryValidPaths: {
auto paths = readStorePaths<StorePathSet>(*store, from);
logger->startWork();
auto res = store->queryValidPaths(paths);
logger->stopWork();
writeStorePaths(*store, to, res);
break;
}
case wopHasSubstitutes: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
StorePathSet paths; // FIXME
paths.insert(path);
auto res = store->querySubstitutablePaths(paths);
logger->stopWork();
to << (res.count(path) != 0);
break;
}
case wopQuerySubstitutablePaths: {
auto paths = readStorePaths<StorePathSet>(*store, from);
logger->startWork();
auto res = store->querySubstitutablePaths(paths);
logger->stopWork();
writeStorePaths(*store, to, res);
break;
}
case wopQueryPathHash: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
auto hash = store->queryPathInfo(path)->narHash;
logger->stopWork();
to << hash.to_string(Base16, false);
break;
}
case wopQueryReferences:
case wopQueryReferrers:
case wopQueryValidDerivers:
case wopQueryDerivationOutputs: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
StorePathSet paths;
if (op == wopQueryReferences)
for (auto & i : store->queryPathInfo(path)->references)
paths.insert(i);
else if (op == wopQueryReferrers)
store->queryReferrers(path, paths);
else if (op == wopQueryValidDerivers)
paths = store->queryValidDerivers(path);
else paths = store->queryDerivationOutputs(path);
logger->stopWork();
writeStorePaths(*store, to, paths);
break;
}
case wopQueryDerivationOutputNames: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
auto names = store->readDerivation(path).outputNames();
logger->stopWork();
to << names;
break;
}
case wopQueryDeriver: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
auto info = store->queryPathInfo(path);
logger->stopWork();
to << (info->deriver ? store->printStorePath(*info->deriver) : "");
break;
}
case wopQueryPathFromHashPart: {
auto hashPart = readString(from);
logger->startWork();
auto path = store->queryPathFromHashPart(hashPart);
logger->stopWork();
to << (path ? store->printStorePath(*path) : "");
break;
}
case wopAddToStore: {
std::string s, baseName;
FileIngestionMethod method;
{
bool fixed; uint8_t recursive;
from >> baseName >> fixed /* obsolete */ >> recursive >> s;
if (recursive > (uint8_t) FileIngestionMethod::Recursive)
throw Error("unsupported FileIngestionMethod with value of %i; you may need to upgrade nix-daemon", recursive);
method = FileIngestionMethod { recursive };
/* Compatibility hack. */
if (!fixed) {
s = "sha256";
method = FileIngestionMethod::Recursive;
}
}
HashType hashAlgo = parseHashType(s);
TeeSource savedNAR(from);
RetrieveRegularNARSink savedRegular;
if (method == FileIngestionMethod::Recursive) {
/* Get the entire NAR dump from the client and save it to
a string so that we can pass it to
addToStoreFromDump(). */
ParseSink sink; /* null sink; just parse the NAR */
parseDump(sink, savedNAR);
} else
parseDump(savedRegular, from);
logger->startWork();
if (!savedRegular.regular) throw Error("regular file expected");
auto path = store->addToStoreFromDump(
method == FileIngestionMethod::Recursive ? *savedNAR.data : savedRegular.s,
baseName,
method,
hashAlgo);
logger->stopWork();
to << store->printStorePath(path);
break;
}
case wopAddTextToStore: {
string suffix = readString(from);
string s = readString(from);
auto refs = readStorePaths<StorePathSet>(*store, from);
logger->startWork();
auto path = store->addTextToStore(suffix, s, refs, NoRepair);
logger->stopWork();
to << store->printStorePath(path);
break;
}
case wopExportPath: {
auto path = store->parseStorePath(readString(from));
readInt(from); // obsolete
logger->startWork();
TunnelSink sink(to);
store->exportPath(path, sink);
logger->stopWork();
to << 1;
break;
}
case wopImportPaths: {
logger->startWork();
TunnelSource source(from, to);
auto paths = store->importPaths(source, nullptr,
trusted ? NoCheckSigs : CheckSigs);
logger->stopWork();
Strings paths2;
for (auto & i : paths) paths2.push_back(store->printStorePath(i));
to << paths2;
break;
}
case wopBuildPaths: {
std::vector<StorePathWithOutputs> drvs;
for (auto & s : readStrings<Strings>(from))
drvs.push_back(store->parsePathWithOutputs(s));
BuildMode mode = bmNormal;
if (GET_PROTOCOL_MINOR(clientVersion) >= 15) {
mode = (BuildMode) readInt(from);
/* Repairing is not atomic, so disallowed for "untrusted"
clients. */
if (mode == bmRepair && !trusted)
throw Error("repairing is not allowed because you are not in 'trusted-users'");
}
logger->startWork();
store->buildPaths(drvs, mode);
logger->stopWork();
to << 1;
break;
}
case wopBuildDerivation: {
auto drvPath = store->parseStorePath(readString(from));
BasicDerivation drv;
readDerivation(from, *store, drv);
BuildMode buildMode = (BuildMode) readInt(from);
logger->startWork();
if (!trusted)
throw Error("you are not privileged to build derivations");
auto res = store->buildDerivation(drvPath, drv, buildMode);
logger->stopWork();
to << res.status << res.errorMsg;
break;
}
case wopEnsurePath: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
store->ensurePath(path);
logger->stopWork();
to << 1;
break;
}
case wopAddTempRoot: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
store->addTempRoot(path);
logger->stopWork();
to << 1;
break;
}
case wopAddIndirectRoot: {
Path path = absPath(readString(from));
logger->startWork();
store->addIndirectRoot(path);
logger->stopWork();
to << 1;
break;
}
case wopSyncWithGC: {
logger->startWork();
store->syncWithGC();
logger->stopWork();
to << 1;
break;
}
case wopFindRoots: {
logger->startWork();
Roots roots = store->findRoots(!trusted);
logger->stopWork();
size_t size = 0;
for (auto & i : roots)
size += i.second.size();
to << size;
for (auto & [target, links] : roots)
for (auto & link : links)
to << link << store->printStorePath(target);
break;
}
case wopCollectGarbage: {
GCOptions options;
options.action = (GCOptions::GCAction) readInt(from);
options.pathsToDelete = readStorePaths<StorePathSet>(*store, from);
from >> options.ignoreLiveness >> options.maxFreed;
// obsolete fields
readInt(from);
readInt(from);
readInt(from);
GCResults results;
logger->startWork();
if (options.ignoreLiveness)
throw Error("you are not allowed to ignore liveness");
store->collectGarbage(options, results);
logger->stopWork();
to << results.paths << results.bytesFreed << 0 /* obsolete */;
break;
}
case wopSetOptions: {
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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ClientSettings clientSettings;
clientSettings.keepFailed = readInt(from);
clientSettings.keepGoing = readInt(from);
clientSettings.tryFallback = readInt(from);
clientSettings.verbosity = (Verbosity) readInt(from);
clientSettings.maxBuildJobs = readInt(from);
clientSettings.maxSilentTime = readInt(from);
readInt(from); // obsolete useBuildHook
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
2018-10-02 14:01:26 +00:00
clientSettings.verboseBuild = lvlError == (Verbosity) readInt(from);
readInt(from); // obsolete logType
readInt(from); // obsolete printBuildTrace
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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clientSettings.buildCores = readInt(from);
clientSettings.useSubstitutes = readInt(from);
if (GET_PROTOCOL_MINOR(clientVersion) >= 12) {
unsigned int n = readInt(from);
for (unsigned int i = 0; i < n; i++) {
string name = readString(from);
string value = readString(from);
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
2018-10-02 14:01:26 +00:00
clientSettings.overrides.emplace(name, value);
}
}
logger->startWork();
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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// FIXME: use some setting in recursive mode. Will need to use
// non-global variables.
if (!recursive)
clientSettings.apply(trusted);
logger->stopWork();
break;
}
case wopQuerySubstitutablePathInfo: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
SubstitutablePathInfos infos;
store->querySubstitutablePathInfos({path}, infos);
logger->stopWork();
auto i = infos.find(path);
if (i == infos.end())
to << 0;
else {
to << 1
<< (i->second.deriver ? store->printStorePath(*i->second.deriver) : "");
writeStorePaths(*store, to, i->second.references);
to << i->second.downloadSize
<< i->second.narSize;
}
break;
}
case wopQuerySubstitutablePathInfos: {
auto paths = readStorePaths<StorePathSet>(*store, from);
logger->startWork();
SubstitutablePathInfos infos;
store->querySubstitutablePathInfos(paths, infos);
logger->stopWork();
to << infos.size();
for (auto & i : infos) {
to << store->printStorePath(i.first)
<< (i.second.deriver ? store->printStorePath(*i.second.deriver) : "");
writeStorePaths(*store, to, i.second.references);
to << i.second.downloadSize << i.second.narSize;
}
break;
}
case wopQueryAllValidPaths: {
logger->startWork();
auto paths = store->queryAllValidPaths();
logger->stopWork();
writeStorePaths(*store, to, paths);
break;
}
case wopQueryPathInfo: {
auto path = store->parseStorePath(readString(from));
std::shared_ptr<const ValidPathInfo> info;
logger->startWork();
try {
info = store->queryPathInfo(path);
} catch (InvalidPath &) {
if (GET_PROTOCOL_MINOR(clientVersion) < 17) throw;
}
logger->stopWork();
if (info) {
if (GET_PROTOCOL_MINOR(clientVersion) >= 17)
to << 1;
to << (info->deriver ? store->printStorePath(*info->deriver) : "")
<< info->narHash.to_string(Base16, false);
writeStorePaths(*store, to, info->references);
to << info->registrationTime << info->narSize;
if (GET_PROTOCOL_MINOR(clientVersion) >= 16) {
to << info->ultimate
<< info->sigs
<< info->ca;
}
} else {
assert(GET_PROTOCOL_MINOR(clientVersion) >= 17);
to << 0;
}
break;
}
case wopOptimiseStore:
logger->startWork();
store->optimiseStore();
logger->stopWork();
to << 1;
break;
case wopVerifyStore: {
bool checkContents, repair;
from >> checkContents >> repair;
logger->startWork();
if (repair && !trusted)
throw Error("you are not privileged to repair paths");
bool errors = store->verifyStore(checkContents, (RepairFlag) repair);
logger->stopWork();
to << errors;
break;
}
case wopAddSignatures: {
auto path = store->parseStorePath(readString(from));
StringSet sigs = readStrings<StringSet>(from);
logger->startWork();
if (!trusted)
throw Error("you are not privileged to add signatures");
store->addSignatures(path, sigs);
logger->stopWork();
to << 1;
break;
}
case wopNarFromPath: {
auto path = store->parseStorePath(readString(from));
logger->startWork();
logger->stopWork();
dumpPath(store->printStorePath(path), to);
break;
}
case wopAddToStoreNar: {
bool repair, dontCheckSigs;
ValidPathInfo info(store->parseStorePath(readString(from)));
auto deriver = readString(from);
if (deriver != "")
info.deriver = store->parseStorePath(deriver);
info.narHash = Hash(readString(from), htSHA256);
info.references = readStorePaths<StorePathSet>(*store, from);
from >> info.registrationTime >> info.narSize >> info.ultimate;
info.sigs = readStrings<StringSet>(from);
from >> info.ca >> repair >> dontCheckSigs;
if (!trusted && dontCheckSigs)
dontCheckSigs = false;
if (!trusted)
info.ultimate = false;
std::string saved;
std::unique_ptr<Source> source;
if (GET_PROTOCOL_MINOR(clientVersion) >= 21)
source = std::make_unique<TunnelSource>(from, to);
else {
TeeSource tee(from);
ParseSink sink;
parseDump(sink, tee);
saved = std::move(*tee.data);
source = std::make_unique<StringSource>(saved);
}
logger->startWork();
// FIXME: race if addToStore doesn't read source?
store->addToStore(info, *source, (RepairFlag) repair,
dontCheckSigs ? NoCheckSigs : CheckSigs, nullptr);
logger->stopWork();
break;
}
case wopQueryMissing: {
std::vector<StorePathWithOutputs> targets;
for (auto & s : readStrings<Strings>(from))
targets.push_back(store->parsePathWithOutputs(s));
logger->startWork();
StorePathSet willBuild, willSubstitute, unknown;
unsigned long long downloadSize, narSize;
store->queryMissing(targets, willBuild, willSubstitute, unknown, downloadSize, narSize);
logger->stopWork();
writeStorePaths(*store, to, willBuild);
writeStorePaths(*store, to, willSubstitute);
writeStorePaths(*store, to, unknown);
to << downloadSize << narSize;
break;
}
default:
throw Error("invalid operation %1%", op);
}
}
void processConnection(
ref<Store> store,
FdSource & from,
FdSink & to,
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
2018-10-02 14:01:26 +00:00
TrustedFlag trusted,
RecursiveFlag recursive,
const std::string & userName,
uid_t userId)
{
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
2018-10-02 14:01:26 +00:00
auto monitor = !recursive ? std::make_unique<MonitorFdHup>(from.fd) : nullptr;
/* Exchange the greeting. */
unsigned int magic = readInt(from);
if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
to << WORKER_MAGIC_2 << PROTOCOL_VERSION;
to.flush();
unsigned int clientVersion = readInt(from);
if (clientVersion < 0x10a)
throw Error("the Nix client version is too old");
auto tunnelLogger = new TunnelLogger(to, clientVersion);
auto prevLogger = nix::logger;
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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// FIXME
if (!recursive)
logger = tunnelLogger;
unsigned int opCount = 0;
Finally finally([&]() {
_isInterrupted = false;
prevLogger->log(lvlDebug, fmt("%d operations", opCount));
});
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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if (GET_PROTOCOL_MINOR(clientVersion) >= 14 && readInt(from)) {
auto affinity = readInt(from);
setAffinityTo(affinity);
}
readInt(from); // obsolete reserveSpace
/* Send startup error messages to the client. */
tunnelLogger->startWork();
try {
/* If we can't accept clientVersion, then throw an error
*here* (not above). */
#if 0
/* Prevent users from doing something very dangerous. */
if (geteuid() == 0 &&
querySetting("build-users-group", "") == "")
throw Error("if you run 'nix-daemon' as root, then you MUST set 'build-users-group'!");
#endif
store->createUser(userName, userId);
tunnelLogger->stopWork();
to.flush();
/* Process client requests. */
while (true) {
WorkerOp op;
try {
op = (WorkerOp) readInt(from);
} catch (Interrupted & e) {
break;
} catch (EndOfFile & e) {
break;
}
opCount++;
try {
Recursive Nix support This allows Nix builders to call Nix to build derivations, with some limitations. Example: let nixpkgs = fetchTarball channel:nixos-18.03; in with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ nix jq ]; NIX_PATH = "nixpkgs=${nixpkgs}"; } '' hello=$(nix-build -E '(import <nixpkgs> {}).hello.overrideDerivation (args: { name = "hello-3.5"; })') $hello/bin/hello mkdir -p $out/bin ln -s $hello/bin/hello $out/bin/hello nix path-info -r --json $hello | jq . '' This derivation makes a recursive Nix call to build GNU Hello and symlinks it from its $out, i.e. # ll ./result/bin/ lrwxrwxrwx 1 root root 63 Jan 1 1970 hello -> /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5/bin/hello # nix-store -qR ./result /nix/store/hwwqshlmazzjzj7yhrkyjydxamvvkfd3-glibc-2.26-131 /nix/store/s0awxrs71gickhaqdwxl506hzccb30y5-hello-3.5 /nix/store/sgmvvyw8vhfqdqb619bxkcpfn9lvd8ss-foo This is implemented as follows: * Before running the outer builder, Nix creates a Unix domain socket '.nix-socket' in the builder's temporary directory and sets $NIX_REMOTE to point to it. It starts a thread to process connections to this socket. (Thus you don't need to have nix-daemon running.) * The daemon thread uses a wrapper store (RestrictedStore) to keep track of paths added through recursive Nix calls, to implement some restrictions (see below), and to do some censorship (e.g. for purity, queryPathInfo() won't return impure information such as signatures and timestamps). * After the build finishes, the output paths are scanned for references to the paths added through recursive Nix calls (in addition to the inputs closure). Thus, in the example above, $out has a reference to $hello. The main restriction on recursive Nix calls is that they cannot do arbitrary substitutions. For example, doing nix-store -r /nix/store/kmwd1hq55akdb9sc7l3finr175dajlby-hello-2.10 is forbidden unless /nix/store/kmwd... is in the inputs closure or previously built by a recursive Nix call. This is to prevent irreproducible derivations that have hidden dependencies on substituters or the current store contents. Building a derivation is fine, however, and Nix will use substitutes if available. In other words, the builder has to present proof that it knows how to build a desired store path from scratch by constructing a derivation graph for that path. Probably we should also disallow instantiating/building fixed-output derivations (specifically, those that access the network, but currently we have no way to mark fixed-output derivations that don't access the network). Otherwise sandboxed derivations can bypass sandbox restrictions and access the network. When sandboxing is enabled, we make paths appear in the sandbox of the builder by entering the mount namespace of the builder and bind-mounting each path. This is tricky because we do a pivot_root() in the builder to change the root directory of its mount namespace, and thus the host /nix/store is not visible in the mount namespace of the builder. To get around this, just before doing pivot_root(), we branch a second mount namespace that shares its /nix/store mountpoint with the parent. Recursive Nix currently doesn't work on macOS in sandboxed mode (because we can't change the sandbox policy of a running build) and in non-root mode (because setns() barfs).
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performOp(tunnelLogger, store, trusted, recursive, clientVersion, from, to, op);
} catch (Error & e) {
/* If we're not in a state where we can send replies, then
something went wrong processing the input of the
client. This can happen especially if I/O errors occur
during addTextToStore() / importPath(). If that
happens, just send the error message and exit. */
bool errorAllowed = tunnelLogger->state_.lock()->canSendStderr;
tunnelLogger->stopWork(false, e.msg(), e.status);
if (!errorAllowed) throw;
} catch (std::bad_alloc & e) {
tunnelLogger->stopWork(false, "Nix daemon out of memory", 1);
throw;
}
to.flush();
assert(!tunnelLogger->state_.lock()->canSendStderr);
};
} catch (std::exception & e) {
tunnelLogger->stopWork(false, e.what(), 1);
to.flush();
return;
}
}
}