daemon: Implement signed archive import/export.

* guix/scripts/authenticate.scm, nix/scripts/guix-authenticate.in,
  tests/signing-key.pub, tests/signing-key.sec: New files.
* po/POTFILES.in: Add 'guix/scripts/authenticate.scm'.
* guix/store.scm (dump-port): New procedure.
  (process-stderr): Add 'user-port' optional parameter.  Handle
  the %STDERR-WRITE and %STDERR-READ cases as expected.
  (import-paths, export-path, export-paths): New procedures.
* tests/store.scm ("export/import several paths", "import corrupt
  path"): New tests.
* Makefile.am (MODULES): Add 'guix/scripts/authenticate.scm'.
  (EXTRA_DIST): Add 'tests/signing-key.{pub,sec}'.
* daemon.am (libstore_a_CPPFLAGS)[-DNIX_CONF_DIR]: Change 'NIX_CONF_DIR'
  to .../guix.  Change 'OPENSSL_PATH' to 'guix-authenticate'.
* config-daemon.ac: Instantiate 'nix/scripts/guix-authenticate'.
* nix/nix-daemon/guix-daemon.cc (main): Augment $PATH to include
  'settings.nixLibexecDir'.
* test-env.in: Export 'NIX_CONF_DIR' and 'NIX_LIBEXEC_DIR'.  Populate
  $NIX_CONF_DIR.

13 files changed, 273 insertions, 7 deletions

diff --git a/.gitignore b/.gitignore
index a8a5cad74c..09a593e9fa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -84,3 +84,4 @@ GPATH
 GRTAGS
 GTAGS
 /nix-setuid-helper
+/nix/scripts/guix-authenticate
diff --git a/Makefile.am b/Makefile.am
index 2db77d57f3..34846c3e29 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -73,6 +73,7 @@ MODULES =					\
   guix/scripts/hash.scm				\
   guix/scripts/pull.scm				\
   guix/scripts/substitute-binary.scm		\
+  guix/scripts/authenticate.scm			\
   guix/scripts/refresh.scm			\
   guix.scm					\
   $(GNU_SYSTEM_MODULES)
@@ -172,6 +173,8 @@ EXTRA_DIST =					\
   srfi/srfi-64.scm				\
   srfi/srfi-64.upstream.scm			\
   tests/test.drv				\
+  tests/signing-key.pub				\
+  tests/signing-key.sec				\
   build-aux/config.rpath			\
   bootstrap					\
   release.nix					\
diff --git a/config-daemon.ac b/config-daemon.ac
index 5db08d099d..0717141198 100644
--- a/config-daemon.ac
+++ b/config-daemon.ac
@@ -105,6 +105,8 @@ if test "x$guix_build_daemon" = "xyes"; then
     [chmod +x nix/scripts/list-runtime-roots])
   AC_CONFIG_FILES([nix/scripts/substitute-binary],
     [chmod +x nix/scripts/substitute-binary])
+  AC_CONFIG_FILES([nix/scripts/guix-authenticate],
+    [chmod +x nix/scripts/guix-authenticate])
 fi
 
 AM_CONDITIONAL([BUILD_DAEMON], [test "x$guix_build_daemon" = "xyes"])
diff --git a/daemon.am b/daemon.am
index 77bfe71987..27c631b2da 100644
--- a/daemon.am
+++ b/daemon.am
@@ -112,10 +112,10 @@ libstore_a_CPPFLAGS =				\
   -DNIX_DATA_DIR=\"$(datadir)\"			\
   -DNIX_STATE_DIR=\"$(localstatedir)/nix\"	\
   -DNIX_LOG_DIR=\"$(localstatedir)/log/nix\"	\
-  -DNIX_CONF_DIR=\"$(sysconfdir)/nix\"		\
+  -DNIX_CONF_DIR=\"$(sysconfdir)/guix\"		\
   -DNIX_LIBEXEC_DIR=\"$(libexecdir)\"		\
   -DNIX_BIN_DIR=\"$(bindir)\"			\
-  -DOPENSSL_PATH="\"openssl\""
+  -DOPENSSL_PATH="\"guix-authenticate\""
 
 libstore_a_CXXFLAGS =				\
   $(SQLITE3_CFLAGS) $(LIBGCRYPT_CFLAGS)
diff --git a/guix/scripts/authenticate.scm b/guix/scripts/authenticate.scm
new file mode 100644
index 0000000000..cbafed79d0
--- /dev/null
+++ b/guix/scripts/authenticate.scm
@@ -0,0 +1,98 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix scripts authenticate)
+  #:use-module (guix config)
+  #:use-module (guix utils)
+  #:use-module (guix pk-crypto)
+  #:use-module (guix ui)
+  #:use-module (rnrs io ports)
+  #:use-module (ice-9 match)
+  #:export (guix-authenticate))
+
+;;; Commentary:
+;;;
+;;; This program is used internally by the daemon to sign exported archive
+;;; (the 'export-paths' RPC), and to authenticate imported archives (the
+;;; 'import-paths' RPC.)
+;;;
+;;; Code:
+
+(define (read-gcry-sexp file)
+  "Read a gcrypt sexp from FILE and return it."
+  (call-with-input-file file
+    (compose string->gcry-sexp get-string-all)))
+
+(define (read-hash-data file)
+  "Read sha256 hash data from FILE and return it as a gcrypt sexp."
+  (let* ((hex (call-with-input-file file get-string-all))
+         (bv  (base16-string->bytevector (string-trim-both hex))))
+    (bytevector->hash-data bv)))
+
+
+;;;
+;;; Entry point with 'openssl'-compatible interface.  We support this
+;;; interface because that's what the daemon expects, and we want to leave it
+;;; unmodified currently.
+;;;
+
+(define (guix-authenticate . args)
+  (match args
+    (("rsautl" "-sign" "-inkey" key "-in" hash-file)
+     ;; Sign the hash in HASH-FILE with KEY, and return an sexp that includes
+     ;; both the hash and the actual signature.
+     (let* ((secret-key (read-gcry-sexp key))
+            (data       (read-hash-data hash-file)))
+       (format #t
+               "(guix-signature ~a (payload ~a))"
+               (gcry-sexp->string (sign data secret-key))
+               (gcry-sexp->string data))
+       #t))
+    (("rsautl" "-verify" "-inkey" key "-pubin" "-in" signature-file)
+     ;; Read the signature as produced above, check it against KEY, and print
+     ;; the signed data to stdout upon success.
+     (let* ((public-key (read-gcry-sexp key))
+            (sig+data   (read-gcry-sexp signature-file))
+            (data       (find-sexp-token sig+data 'payload))
+            (signature  (find-sexp-token sig+data 'sig-val)))
+       (if (and data signature)
+           (if (verify signature data public-key)
+               (begin
+                 (display (bytevector->base16-string
+                           (hash-data->bytevector data)))
+                 #t)                              ; success
+               (begin
+                 (format (current-error-port)
+                         "error: invalid signature: ~a~%"
+                         (gcry-sexp->string signature))
+                 (exit 1)))
+           (begin
+             (format (current-error-port)
+                     "error: corrupt signature data: ~a~%"
+                     (gcry-sexp->string sig+data))
+             (exit 1)))))
+    (("--help")
+     (display (_ "Usage: guix authenticate OPTION...
+Sign or verify the signature on the given file.  This tool is meant to
+be used internally by 'guix-daemon'.\n")))
+    (("--version")
+     (show-version-and-exit "guix authenticate"))
+    (else
+     (leave (_ "wrong arguments")))))
+
+;;; authenticate.scm ends here
diff --git a/guix/store.scm b/guix/store.scm
index 08b0671b29..4ceca0daa2 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -80,6 +80,8 @@
             dead-paths
             collect-garbage
             delete-paths
+            import-paths
+            export-paths
 
             current-build-output-port
 
@@ -323,7 +325,30 @@ operate, should the disk become full.  Return a server object."
   ;; The port where build output is sent.
   (make-parameter (current-error-port)))
 
-(define (process-stderr server)
+(define* (dump-port in out
+                    #:optional len
+                    #:key (buffer-size 16384))
+  "Read LEN bytes from IN (or as much as possible if LEN is #f) and write it
+to OUT, using chunks of BUFFER-SIZE bytes."
+  (define buffer
+    (make-bytevector buffer-size))
+
+  (let loop ((total 0)
+             (bytes (get-bytevector-n! in buffer 0
+                                       (if len
+                                           (min len buffer-size)
+                                           buffer-size))))
+    (or (eof-object? bytes)
+        (and len (= total len))
+        (let ((total (+ total bytes)))
+          (put-bytevector out buffer 0 bytes)
+          (loop total
+                (get-bytevector-n! in buffer 0
+                                   (if len
+                                       (min (- len total) buffer-size)
+                                       buffer-size)))))))
+
+(define* (process-stderr server #:optional user-port)
   "Read standard output and standard error from SERVER, writing it to
 CURRENT-BUILD-OUTPUT-PORT.  Return #t when SERVER is done sending data, and
 #f otherwise; in the latter case, the caller should call `process-stderr'
@@ -344,17 +369,30 @@ encoding conversion errors."
 
   (let ((k (read-int p)))
     (cond ((= k %stderr-write)
-           (read-latin1-string p)
+           ;; Write a byte stream to USER-PORT.
+           (let* ((len (read-int p))
+                  (m   (modulo len 8)))
+             (dump-port p user-port len)
+             (unless (zero? m)
+               ;; Consume padding, as for strings.
+               (get-bytevector-n p (- 8 m))))
            #f)
           ((= k %stderr-read)
-           (let ((len (read-int p)))
-             (read-latin1-string p)               ; FIXME: what to do?
+           ;; Read a byte stream from USER-PORT.
+           (let* ((max-len (read-int p))
+                  (data    (get-bytevector-n user-port max-len))
+                  (len     (bytevector-length data)))
+             (write-int len p)
+             (put-bytevector p data)
+             (write-padding len p)
              #f))
           ((= k %stderr-next)
+           ;; Log a string.
            (let ((s (read-latin1-string p)))
              (display s (current-build-output-port))
              #f))
           ((= k %stderr-error)
+           ;; Report an error.
            (let ((error  (read-latin1-string p))
                  ;; Currently the daemon fails to send a status code for early
                  ;; errors like DB schema version mismatches, so check for EOF.
@@ -624,6 +662,39 @@ MIN-FREED bytes have been collected.  Return the paths that were
 collected, and the number of bytes freed."
   (run-gc server (gc-action delete-specific) paths min-freed))
 
+(define (import-paths server port)
+  "Import the set of store paths read from PORT into SERVER's store.  An error
+is raised if the set of paths read from PORT is not signed (as per
+'export-path #:sign? #t'.)  Return the list of store paths imported."
+  (let ((s (nix-server-socket server)))
+    (write-int (operation-id import-paths) s)
+    (let loop ((done? (process-stderr server port)))
+      (or done? (loop (process-stderr server port))))
+    (read-store-path-list s)))
+
+(define* (export-path server path port #:key (sign? #t))
+  "Export PATH to PORT.  When SIGN? is true, sign it."
+  (let ((s (nix-server-socket server)))
+    (write-int (operation-id export-path) s)
+    (write-store-path path s)
+    (write-arg boolean sign? s)
+    (let loop ((done? (process-stderr server port)))
+      (or done? (loop (process-stderr server port))))
+    (= 1 (read-int s))))
+
+(define* (export-paths server paths port #:key (sign? #t))
+  "Export the store paths listed in PATHS to PORT, signing them if SIGN?
+is true."
+  (let ((s (nix-server-socket server)))
+    (let loop ((paths paths))
+      (match paths
+        (()
+         (write-int 0 port))
+        ((head tail ...)
+         (write-int 1 port)
+         (and (export-path server head port #:sign? sign?)
+              (loop tail)))))))
+
 
 ;;;
 ;;; Store paths.
diff --git a/nix/nix-daemon/guix-daemon.cc b/nix/nix-daemon/guix-daemon.cc
index 484a390936..cf87e39354 100644
--- a/nix/nix-daemon/guix-daemon.cc
+++ b/nix/nix-daemon/guix-daemon.cc
@@ -216,6 +216,12 @@ main (int argc, char *argv[])
     {
       settings.processEnvironment ();
 
+      /* Hackily help 'local-store.cc' find our 'guix-authenticate' program, which
+	 is known as 'OPENSSL_PATH' here.  */
+      std::string search_path (getenv ("PATH"));
+      search_path = settings.nixLibexecDir + ":" + search_path;
+      setenv ("PATH", search_path.c_str (), 1);
+
       /* Use our substituter by default.  */
       settings.substituters.clear ();
       settings.useSubstitutes = true;
diff --git a/nix/scripts/guix-authenticate.in b/nix/scripts/guix-authenticate.in
new file mode 100644
index 0000000000..5ce57915f0
--- /dev/null
+++ b/nix/scripts/guix-authenticate.in
@@ -0,0 +1,11 @@
+#!@SHELL@
+# A shorthand for "guix authenticate", for use by the daemon.
+
+if test "x$GUIX_UNINSTALLED" = "x"
+then
+    prefix="@prefix@"
+    exec_prefix="@exec_prefix@"
+    exec "@bindir@/guix" authenticate "$@"
+else
+    exec guix authenticate "$@"
+fi
diff --git a/po/POTFILES.in b/po/POTFILES.in
index 0e30bb0880..beefdc901b 100644
--- a/po/POTFILES.in
+++ b/po/POTFILES.in
@@ -11,6 +11,7 @@ guix/scripts/gc.scm
 guix/scripts/hash.scm
 guix/scripts/pull.scm
 guix/scripts/substitute-binary.scm
+guix/scripts/authenticate.scm
 guix/gnu-maintenance.scm
 guix/ui.scm
 guix/http-client.scm
diff --git a/test-env.in b/test-env.in
index 9224a80537..df73ecdc7a 100644
--- a/test-env.in
+++ b/test-env.in
@@ -40,6 +40,22 @@ then
     # Currently, in Nix builds, we're at ~106 chars...
     NIX_STATE_DIR="@GUIX_TEST_ROOT@/var/$$"
 
+    # The configuration directory, for import/export signing keys.
+    NIX_CONF_DIR="@GUIX_TEST_ROOT@/etc"
+    if [ ! -d "$NIX_CONF_DIR" ]
+    then
+	# Copy the keys so that the secret key has the right permissions (the
+	# daemon errors out when this is not the case.)
+	mkdir -p "$NIX_CONF_DIR"
+	cp "@abs_top_srcdir@/tests/signing-key.sec"	\
+	    "@abs_top_srcdir@/tests/signing-key.pub"	\
+	    "$NIX_CONF_DIR"
+	chmod 400 "$NIX_CONF_DIR/signing-key.sec"
+    fi
+
+    # For 'guix-authenticate'.
+    NIX_LIBEXEC_DIR="@abs_top_builddir@/nix/scripts"
+
     # A place to store data of the substituter.
     GUIX_BINARY_SUBSTITUTE_URL="file://$NIX_STATE_DIR/substituter-data"
     rm -rf "$NIX_STATE_DIR/substituter-data"
@@ -51,7 +67,7 @@ then
     export NIX_IGNORE_SYMLINK_STORE NIX_STORE_DIR			\
 	NIX_LOCALSTATE_DIR NIX_LOG_DIR NIX_STATE_DIR NIX_DB_DIR		\
 	NIX_ROOT_FINDER NIX_SETUID_HELPER GUIX_BINARY_SUBSTITUTE_URL	\
-        XDG_CACHE_HOME
+        NIX_CONF_DIR NIX_LIBEXEC_DIR XDG_CACHE_HOME
 
     # Do that because store.scm calls `canonicalize-path' on it.
     mkdir -p "$NIX_STORE_DIR"
diff --git a/tests/signing-key.pub b/tests/signing-key.pub
new file mode 100644
index 0000000000..092424a15d
--- /dev/null
+++ b/tests/signing-key.pub
@@ -0,0 +1,4 @@
+(public-key
+ (rsa
+  (n #00C1F764069F54FFE93A126B02328903E984E4AE3AF6DF402B5B6B3907911B88C385F1BA76A002EC9DEA109A5228EF0E62EE31A06D1A5861CAB474F6C857AC66EB65A1905F25BBA1869579E73A3B7FED13AF5A1667326F88CDFC2FF24B03C14FD1384AA7E73CA89572880B606E3A974E15347963FC7B6378574936A47580DBCB45#)
+  (e #010001#)))
diff --git a/tests/signing-key.sec b/tests/signing-key.sec
new file mode 100644
index 0000000000..558e189102
--- /dev/null
+++ b/tests/signing-key.sec
@@ -0,0 +1,8 @@
+(private-key
+ (rsa
+  (n #00C1F764069F54FFE93A126B02328903E984E4AE3AF6DF402B5B6B3907911B88C385F1BA76A002EC9DEA109A5228EF0E62EE31A06D1A5861CAB474F6C857AC66EB65A1905F25BBA1869579E73A3B7FED13AF5A1667326F88CDFC2FF24B03C14FD1384AA7E73CA89572880B606E3A974E15347963FC7B6378574936A47580DBCB45#)
+  (e #010001#)
+  (d #58CAD84653D0046A8EC3F9AA82D9C829B145422109FC3F12DA01A694B92FA296E70D366FB166454D30E632CEE3A033B4C41781BA10325F69FCDC0250CA19C8EEB352FA085992494098DB133E682ED38A931701F0DED1A1E508F4341A4FB446A04F019427C7CB3C44F251EEA9D386100DA80F125E0FD5CE1B0DFEC6D21516EACD#)
+  (p #00D47F185147EC39393CCDA4E7323FFC20FC8B8073E2A54DD63BA392A66975E4204CA48572496A9DFD7522436B852C07472A5AB25B7706F7C14E6F33FBC420FF3B#)
+  (q #00E9AD22F158060BC9AE3601DA623AFC60FFF3058795802CA92371C00097335CF9A23D7782DE353C9DBA93D7BB99E6A24A411107605E722481C5C191F80D7EB77F#)
+  (u #59B45B95AE01A7A7370FAFDB08FE73A4793CE37F228961B09B1B1E7DDAD9F8D3E28F5C5E8B4B067E6B8E0BBF3F690B42991A79E46108DDCDA2514323A66964DE#)))
diff --git a/tests/store.scm b/tests/store.scm
index 281b923c28..6834ebc5e9 100644
--- a/tests/store.scm
+++ b/tests/store.scm
@@ -28,10 +28,12 @@
   #:use-module (gnu packages)
   #:use-module (gnu packages bootstrap)
   #:use-module (ice-9 match)
+  #:use-module (rnrs bytevectors)
   #:use-module (rnrs io ports)
   #:use-module (web uri)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-64))
 
@@ -344,6 +346,49 @@ Deriver: ~a~%"
            (build-derivations s (list d))
            #f))))
 
+(test-assert "export/import several paths"
+  (let* ((texts (unfold (cut >= <> 10)
+                        (lambda _ (random-text))
+                        1+
+                        0))
+         (files (map (cut add-text-to-store %store "text" <>) texts))
+         (dump  (call-with-bytevector-output-port
+                 (cut export-paths %store files <>))))
+    (delete-paths %store files)
+    (and (every (negate file-exists?) files)
+         (let* ((source   (open-bytevector-input-port dump))
+                (imported (import-paths %store source)))
+           (and (equal? imported files)
+                (every file-exists? files)
+                (equal? texts
+                        (map (lambda (file)
+                               (call-with-input-file file
+                                 get-string-all))
+                             files)))))))
+
+(test-assert "import corrupt path"
+  (let* ((text (random-text))
+         (file (add-text-to-store %store "text" text))
+         (dump (call-with-bytevector-output-port
+                (cut export-paths %store (list file) <>))))
+    (delete-paths %store (list file))
+
+    ;; Flip a bit in the middle of the stream.
+    (let* ((index (quotient (bytevector-length dump) 3))
+           (byte  (bytevector-u8-ref dump index)))
+      (bytevector-u8-set! dump index (logxor #xff byte)))
+
+    (and (not (file-exists? file))
+         (guard (c ((nix-protocol-error? c)
+                    (pk 'c c)
+                    (and (not (zero? (nix-protocol-error-status c)))
+                         (string-contains (nix-protocol-error-message c)
+                                          "corrupt"))))
+           (let* ((source   (open-bytevector-input-port dump))
+                  (imported (import-paths %store source)))
+             (pk 'corrupt-imported imported)
+             #f)))))
+
 (test-end "store")