From 0fdf4da0e979f992db75cc17376e455ddc5a96d8 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 8 Jan 2014 15:23:41 +0100 Subject: Support cryptographically signed binary caches MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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. --- perl/lib/Nix/Config.pm.in | 3 ++- perl/lib/Nix/Crypto.pm | 42 ++++++++++++++++++++++++++++++++++++++++++ perl/lib/Nix/Manifest.pm | 40 +++++++++++++++++++++++++++++++++++++--- 3 files changed, 81 insertions(+), 4 deletions(-) create mode 100644 perl/lib/Nix/Crypto.pm (limited to 'perl/lib') diff --git a/perl/lib/Nix/Config.pm.in b/perl/lib/Nix/Config.pm.in index 8c902ab6e..4f1f38ddd 100644 --- a/perl/lib/Nix/Config.pm.in +++ b/perl/lib/Nix/Config.pm.in @@ -13,6 +13,7 @@ $storeDir = $ENV{"NIX_STORE_DIR"} || "@storedir@"; $bzip2 = "@bzip2@"; $xz = "@xz@"; $curl = "@curl@"; +$openssl = "@openssl@"; $useBindings = "@perlbindings@" eq "yes"; @@ -32,7 +33,7 @@ sub readConfig { open CONFIG, "<$config" or die "cannot open `$config'"; while () { - /^\s*([\w|-]+)\s*=\s*(.*)$/ or next; + /^\s*([\w\-\.]+)\s*=\s*(.*)$/ or next; $config{$1} = $2; } close CONFIG; diff --git a/perl/lib/Nix/Crypto.pm b/perl/lib/Nix/Crypto.pm new file mode 100644 index 000000000..0286e88d3 --- /dev/null +++ b/perl/lib/Nix/Crypto.pm @@ -0,0 +1,42 @@ +package Nix::Crypto; + +use strict; +use MIME::Base64; +use Nix::Store; +use Nix::Config; +use IPC::Open2; + +our @ISA = qw(Exporter); +our @EXPORT = qw(signString isValidSignature); + +sub signString { + my ($privateKeyFile, $s) = @_; + my $hash = hashString("sha256", 0, $s); + my ($from, $to); + my $pid = open2($from, $to, $Nix::Config::openssl, "rsautl", "-sign", "-inkey", $privateKeyFile); + print $to $hash; + close $to; + local $/ = undef; + my $sig = <$from>; + close $from; + waitpid($pid, 0); + die "$0: OpenSSL returned exit code $? while signing hash\n" if $? != 0; + my $sig64 = encode_base64($sig, ""); + return $sig64; +} + +sub isValidSignature { + my ($publicKeyFile, $sig64, $s) = @_; + my ($from, $to); + my $pid = open2($from, $to, $Nix::Config::openssl, "rsautl", "-verify", "-inkey", $publicKeyFile, "-pubin"); + print $to decode_base64($sig64); + close $to; + my $decoded = <$from>; + close $from; + waitpid($pid, 0); + return 0 if $? != 0; + my $hash = hashString("sha256", 0, $s); + return $decoded eq $hash; +} + +1; diff --git a/perl/lib/Nix/Manifest.pm b/perl/lib/Nix/Manifest.pm index 04c699b43..015c92835 100644 --- a/perl/lib/Nix/Manifest.pm +++ b/perl/lib/Nix/Manifest.pm @@ -8,6 +8,7 @@ use File::stat; use File::Path; use Fcntl ':flock'; use Nix::Config; +use Nix::Crypto; our @ISA = qw(Exporter); our @EXPORT = qw(readManifest writeManifest updateManifestDB addPatch deleteOldManifests parseNARInfo); @@ -394,9 +395,10 @@ sub deleteOldManifests { # Parse a NAR info file. sub parseNARInfo { - my ($storePath, $content) = @_; + my ($storePath, $content, $requireValidSig, $location) = @_; - my ($storePath2, $url, $fileHash, $fileSize, $narHash, $narSize, $deriver, $system); + my ($storePath2, $url, $fileHash, $fileSize, $narHash, $narSize, $deriver, $system, $sig); + my $signedData = ""; my $compression = "bzip2"; my @refs; @@ -412,11 +414,13 @@ sub parseNARInfo { elsif ($1 eq "References") { @refs = split / /, $2; } elsif ($1 eq "Deriver") { $deriver = $2; } elsif ($1 eq "System") { $system = $2; } + elsif ($1 eq "Signature") { $sig = $2; last; } + $signedData .= "$line\n"; } return undef if $storePath ne $storePath2 || !defined $url || !defined $narHash; - return + my $res = { url => $url , compression => $compression , fileHash => $fileHash @@ -427,6 +431,36 @@ sub parseNARInfo { , deriver => $deriver , system => $system }; + + if ($requireValidSig) { + if (!defined $sig) { + warn "NAR info file `$location' lacks a signature; ignoring\n"; + return undef; + } + my ($sigVersion, $keyName, $sig64) = split ";", $sig; + $sigVersion //= 0; + if ($sigVersion != 1) { + warn "NAR info file `$location' has unsupported version $sigVersion; ignoring\n"; + return undef; + } + return undef unless defined $keyName && defined $sig64; + my $publicKeyFile = $Nix::Config::config{"binary-cache-public-key-$keyName"}; + if (!defined $publicKeyFile) { + warn "NAR info file `$location' is signed by unknown key `$keyName'; ignoring\n"; + return undef; + } + if (! -f $publicKeyFile) { + die "binary cache public key file `$publicKeyFile' does not exist\n"; + return undef; + } + if (!isValidSignature($publicKeyFile, $sig64, $signedData)) { + warn "NAR info file `$location' has an invalid signature; ignoring\n"; + return undef; + } + $res->{signedBy} = $keyName; + } + + return $res; } -- cgit v1.2.3