Support cryptographically signed binary caches
NAR info files in binary caches can now have a cryptographic signature that Nix will verify before using the corresponding NAR file. To create a private/public key pair for signing and verifying a binary cache, do: $ openssl genrsa -out ./cache-key.sec 2048 $ openssl rsa -in ./cache-key.sec -pubout > ./cache-key.pub You should also come up with a symbolic name for the key, such as "cache.example.org-1". This will be used by clients to look up the public key. (It's a good idea to number keys, in case you ever need to revoke/replace one.) To create a binary cache signed with the private key: $ nix-push --dest /path/to/binary-cache --key ./cache-key.sec --key-name cache.example.org-1 The public key (cache-key.pub) should be distributed to the clients. They should have a nix.conf should contain something like: signed-binary-caches = * binary-cache-public-key-cache.example.org-1 = /path/to/cache-key.pub If all works well, then if Nix fetches something from the signed binary cache, you will see a message like: *** Downloading ‘http://cache.example.org/nar/7dppcj5sc1nda7l54rjc0g5l1hamj09j-subversion-1.7.11’ (signed by ‘cache.example.org-1’) to ‘/nix/store/7dppcj5sc1nda7l54rjc0g5l1hamj09j-subversion-1.7.11’... On the other hand, if the signature is wrong, you get a message like NAR info file `http://cache.example.org/7dppcj5sc1nda7l54rjc0g5l1hamj09j.narinfo' has an invalid signature; ignoring Signatures are implemented as a single line appended to the NAR info file, which looks like this: Signature: 1;cache.example.org-1;HQ9Xzyanq9iV...muQ== Thus the signature has 3 fields: a version (currently "1"), the ID of key, and the base64-encoded signature of the SHA-256 hash of the contents of the NAR info file up to but not including the Signature line. Issue #75.
This commit is contained in:
Eelco Dolstra
parent
405434e084
commit
0fdf4da0e9
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@ -1,4 +1,4 @@
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PERL_MODULES = lib/Nix/Store.pm lib/Nix/Manifest.pm lib/Nix/GeneratePatches.pm lib/Nix/SSH.pm lib/Nix/CopyClosure.pm lib/Nix/Config.pm.in lib/Nix/Utils.pm
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PERL_MODULES = lib/Nix/Store.pm lib/Nix/Manifest.pm lib/Nix/GeneratePatches.pm lib/Nix/SSH.pm lib/Nix/CopyClosure.pm lib/Nix/Config.pm.in lib/Nix/Utils.pm lib/Nix/Crypto.pm
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all: $(PERL_MODULES:.in=)
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@ -13,6 +13,7 @@ $storeDir = $ENV{"NIX_STORE_DIR"} || "@storedir@";
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$bzip2 = "@bzip2@";
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$xz = "@xz@";
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$curl = "@curl@";
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$openssl = "@openssl@";
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$useBindings = "@perlbindings@" eq "yes";
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@ -32,7 +33,7 @@ sub readConfig {
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open CONFIG, "<$config" or die "cannot open `$config'";
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while (<CONFIG>) {
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/^\s*([\w|-]+)\s*=\s*(.*)$/ or next;
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/^\s*([\w\-\.]+)\s*=\s*(.*)$/ or next;
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$config{$1} = $2;
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}
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close CONFIG;
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@ -0,0 +1,42 @@
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package Nix::Crypto;
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use strict;
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use MIME::Base64;
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use Nix::Store;
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use Nix::Config;
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use IPC::Open2;
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our @ISA = qw(Exporter);
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our @EXPORT = qw(signString isValidSignature);
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sub signString {
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my ($privateKeyFile, $s) = @_;
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my $hash = hashString("sha256", 0, $s);
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my ($from, $to);
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my $pid = open2($from, $to, $Nix::Config::openssl, "rsautl", "-sign", "-inkey", $privateKeyFile);
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print $to $hash;
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close $to;
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local $/ = undef;
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my $sig = <$from>;
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close $from;
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waitpid($pid, 0);
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die "$0: OpenSSL returned exit code $? while signing hash\n" if $? != 0;
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my $sig64 = encode_base64($sig, "");
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return $sig64;
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}
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sub isValidSignature {
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my ($publicKeyFile, $sig64, $s) = @_;
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my ($from, $to);
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my $pid = open2($from, $to, $Nix::Config::openssl, "rsautl", "-verify", "-inkey", $publicKeyFile, "-pubin");
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print $to decode_base64($sig64);
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close $to;
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my $decoded = <$from>;
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close $from;
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waitpid($pid, 0);
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return 0 if $? != 0;
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my $hash = hashString("sha256", 0, $s);
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return $decoded eq $hash;
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}
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1;
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@ -8,6 +8,7 @@ use File::stat;
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use File::Path;
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use Fcntl ':flock';
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use Nix::Config;
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use Nix::Crypto;
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our @ISA = qw(Exporter);
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our @EXPORT = qw(readManifest writeManifest updateManifestDB addPatch deleteOldManifests parseNARInfo);
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@ -394,9 +395,10 @@ sub deleteOldManifests {
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# Parse a NAR info file.
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sub parseNARInfo {
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my ($storePath, $content) = @_;
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my ($storePath, $content, $requireValidSig, $location) = @_;
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my ($storePath2, $url, $fileHash, $fileSize, $narHash, $narSize, $deriver, $system);
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my ($storePath2, $url, $fileHash, $fileSize, $narHash, $narSize, $deriver, $system, $sig);
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my $signedData = "";
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my $compression = "bzip2";
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my @refs;
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@ -412,11 +414,13 @@ sub parseNARInfo {
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elsif ($1 eq "References") { @refs = split / /, $2; }
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elsif ($1 eq "Deriver") { $deriver = $2; }
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elsif ($1 eq "System") { $system = $2; }
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elsif ($1 eq "Signature") { $sig = $2; last; }
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$signedData .= "$line\n";
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}
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return undef if $storePath ne $storePath2 || !defined $url || !defined $narHash;
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return
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my $res =
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{ url => $url
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, compression => $compression
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, fileHash => $fileHash
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@ -427,6 +431,36 @@ sub parseNARInfo {
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, deriver => $deriver
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, system => $system
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};
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if ($requireValidSig) {
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if (!defined $sig) {
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warn "NAR info file `$location' lacks a signature; ignoring\n";
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return undef;
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}
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my ($sigVersion, $keyName, $sig64) = split ";", $sig;
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$sigVersion //= 0;
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if ($sigVersion != 1) {
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warn "NAR info file `$location' has unsupported version $sigVersion; ignoring\n";
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return undef;
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}
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return undef unless defined $keyName && defined $sig64;
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my $publicKeyFile = $Nix::Config::config{"binary-cache-public-key-$keyName"};
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if (!defined $publicKeyFile) {
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warn "NAR info file `$location' is signed by unknown key `$keyName'; ignoring\n";
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return undef;
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}
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if (! -f $publicKeyFile) {
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die "binary cache public key file `$publicKeyFile' does not exist\n";
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return undef;
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}
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if (!isValidSignature($publicKeyFile, $sig64, $signedData)) {
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warn "NAR info file `$location' has an invalid signature; ignoring\n";
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return undef;
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}
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$res->{signedBy} = $keyName;
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}
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return $res;
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}
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@ -42,6 +42,8 @@ my $caBundle = $ENV{"CURL_CA_BUNDLE"} // $ENV{"OPENSSL_X509_CERT_FILE"};
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my $userName = getpwuid($<) or die "cannot figure out user name";
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my $requireSignedBinaryCaches = ($Nix::Config::config{"signed-binary-caches"} // "0") ne "0";
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sub addRequest {
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my ($storePath, $url, $head) = @_;
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@ -120,9 +122,10 @@ sub processRequests {
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sub initCache {
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my $dbPath = "$Nix::Config::stateDir/binary-cache-v2.sqlite";
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my $dbPath = "$Nix::Config::stateDir/binary-cache-v3.sqlite";
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unlink "$Nix::Config::stateDir/binary-cache-v1.sqlite";
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unlink "$Nix::Config::stateDir/binary-cache-v2.sqlite";
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# Open/create the database.
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$dbh = DBI->connect("dbi:SQLite:dbname=$dbPath", "", "")
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@ -159,7 +162,7 @@ EOF
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narSize integer,
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refs text,
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deriver text,
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system text,
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signedBy text,
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timestamp integer not null,
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primary key (cache, storePath),
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foreign key (cache) references BinaryCaches(id) on delete cascade
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@ -183,7 +186,7 @@ EOF
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$insertNAR = $dbh->prepare(
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"insert or replace into NARs(cache, storePath, url, compression, fileHash, fileSize, narHash, " .
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"narSize, refs, deriver, system, timestamp) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;
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"narSize, refs, deriver, signedBy, timestamp) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die;
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$queryNAR = $dbh->prepare("select * from NARs where cache = ? and storePath = ?") or die;
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@ -309,14 +312,16 @@ sub processNARInfo {
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return undef;
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}
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my $narInfo = parseNARInfo($storePath, $request->{content});
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my $narInfo = parseNARInfo($storePath, $request->{content}, $requireSignedBinaryCaches, $request->{url});
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return undef unless defined $narInfo;
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die if $requireSignedBinaryCaches && !defined $narInfo->{signedBy};
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# Cache the result.
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$insertNAR->execute(
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$cache->{id}, basename($storePath), $narInfo->{url}, $narInfo->{compression},
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$narInfo->{fileHash}, $narInfo->{fileSize}, $narInfo->{narHash}, $narInfo->{narSize},
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join(" ", @{$narInfo->{refs}}), $narInfo->{deriver}, $narInfo->{system}, time())
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join(" ", @{$narInfo->{refs}}), $narInfo->{deriver}, $narInfo->{signedBy}, time())
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if shouldCache $request->{url};
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return $narInfo;
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@ -330,6 +335,10 @@ sub getCachedInfoFrom {
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my $res = $queryNAR->fetchrow_hashref();
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return undef unless defined $res;
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# We may previously have cached this info when signature checking
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# was disabled. In that case, ignore the cached info.
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return undef if $requireSignedBinaryCaches && !defined $res->{signedBy};
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return
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{ url => $res->{url}
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, compression => $res->{compression}
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@ -339,6 +348,7 @@ sub getCachedInfoFrom {
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, narSize => $res->{narSize}
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, refs => [ split " ", $res->{refs} ]
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, deriver => $res->{deriver}
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, signedBy => $res->{signedBy}
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} if defined $res;
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}
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@ -522,7 +532,8 @@ sub downloadBinary {
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next;
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}
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my $url = "$cache->{url}/$info->{url}"; # FIXME: handle non-relative URLs
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print STDERR "\n*** Downloading ‘$url’ to ‘$storePath’...\n";
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die if $requireSignedBinaryCaches && !defined $info->{signedBy};
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print STDERR "\n*** Downloading ‘$url’ ", ($requireSignedBinaryCaches ? "(signed by ‘$info->{signedBy}’) " : ""), "to ‘$storePath’...\n";
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checkURL $url;
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if (system("$Nix::Config::curl --fail --location --insecure '$url' $decompressor | $Nix::Config::binDir/nix-store --restore $destPath") != 0) {
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warn "download of `$url' failed" . ($! ? ": $!" : "") . "\n";
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}
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# Tell Nix about the expected hash so it can verify it.
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die unless defined $info->{narHash} && $info->{narHash} ne "";
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print "$info->{narHash}\n";
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print STDERR "\n";
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@ -10,6 +10,7 @@ use Nix::Config;
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use Nix::Store;
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use Nix::Manifest;
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use Nix::Utils;
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use Nix::Crypto;
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my $tmpDir = tempdir("nix-push.XXXXXX", CLEANUP => 1, TMPDIR => 1)
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or die "cannot create a temporary directory";
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@ -25,6 +26,8 @@ my $writeManifest = 0;
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my $manifestPath;
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my $archivesURL;
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my $link = 0;
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my $privateKeyFile;
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my $keyName;
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my @roots;
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for (my $n = 0; $n < scalar @ARGV; $n++) {
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@ -57,6 +60,14 @@ for (my $n = 0; $n < scalar @ARGV; $n++) {
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$archivesURL = $ARGV[$n];
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} elsif ($arg eq "--link") {
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$link = 1;
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} elsif ($arg eq "--key") {
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$n++;
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die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
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$privateKeyFile = $ARGV[$n];
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} elsif ($arg eq "--key-name") {
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$n++;
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die "$0: `$arg' requires an argument\n" unless $n < scalar @ARGV;
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$keyName = $ARGV[$n];
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} elsif (substr($arg, 0, 1) eq "-") {
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die "$0: unknown flag `$arg'\n";
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} else {
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@ -99,7 +110,7 @@ foreach my $storePath (@storePaths) {
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my $pathHash = substr(basename($storePath), 0, 32);
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my $narInfoFile = "$destDir/$pathHash.narinfo";
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if (-e $narInfoFile) {
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my $narInfo = parseNARInfo($storePath, readFile($narInfoFile));
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my $narInfo = parseNARInfo($storePath, readFile($narInfoFile), 0, $narInfoFile) or die "cannot read `$narInfoFile'\n";
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my $narFile = "$destDir/$narInfo->{url}";
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if (-e $narFile) {
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print STDERR "skipping existing $storePath\n";
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@ -245,6 +256,11 @@ for (my $n = 0; $n < scalar @storePaths2; $n++) {
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}
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}
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if (defined $privateKeyFile && defined $keyName) {
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my $sig = signString($privateKeyFile, $info);
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$info .= "Signature: 1;$keyName;$sig\n";
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}
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my $pathHash = substr(basename($storePath), 0, 32);
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$dst = "$destDir/$pathHash.narinfo";
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@ -35,6 +35,7 @@
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-e "s^@version\@^$(VERSION)^g" \
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-e "s^@perlbindings\@^$(perlbindings)^g" \
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-e "s^@testPath\@^$(coreutils):$$(dirname $$(type -p expr))^g" \
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-e "s^@openssl\@^$(openssl_prog)^g" \
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< $< > $@ || rm $@
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if test -x $<; then chmod +x $@; fi
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@ -40,6 +40,14 @@ nix-store --check-validity $outPath
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nix-store -qR $outPath | grep input-2
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# Test whether this unsigned cache is rejected if the user requires signed caches.
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clearStore
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rm -f $NIX_STATE_DIR/binary-cache*
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nix-store --option binary-caches "file://$cacheDir" --option signed-binary-caches 1 -r $outPath
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# Test whether fallback works if we have cached info but the
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# corresponding NAR has disappeared.
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clearStore
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