diff options
| -rw-r--r-- | Makefile.am | 2 | ||||
| -rw-r--r-- | doc.am | 1 | ||||
| -rw-r--r-- | doc/contributing.texi | 11 | ||||
| -rw-r--r-- | doc/guix.texi | 129 | ||||
| -rw-r--r-- | guix/scripts/challenge.scm | 244 | ||||
| -rw-r--r-- | po/guix/POTFILES.in | 1 | ||||
| -rw-r--r-- | tests/challenge.scm | 114 |
7 files changed, 501 insertions, 1 deletions
diff --git a/Makefile.am b/Makefile.am index 18fbd9d578..6f785e7083 100644 --- a/Makefile.am +++ b/Makefile.am @@ -116,6 +116,7 @@ MODULES = \ guix/scripts/refresh.scm \ guix/scripts/system.scm \ guix/scripts/lint.scm \ + guix/scripts/challenge.scm \ guix/scripts/import/cran.scm \ guix/scripts/import/gnu.scm \ guix/scripts/import/nix.scm \ @@ -218,6 +219,7 @@ SCM_TESTS = \ tests/scripts.scm \ tests/size.scm \ tests/graph.scm \ + tests/challenge.scm \ tests/file-systems.scm \ tests/services.scm \ tests/containers.scm diff --git a/doc.am b/doc.am index 1980cc870e..e3a91cc36d 100644 --- a/doc.am +++ b/doc.am @@ -113,6 +113,7 @@ endef SUBCOMMANDS := \ archive \ build \ + challenge \ download \ edit \ environment \ diff --git a/doc/contributing.texi b/doc/contributing.texi index b2d097dd62..245ce9b1c4 100644 --- a/doc/contributing.texi +++ b/doc/contributing.texi @@ -234,6 +234,17 @@ For important changes, check that dependent package (if applicable) are not affected by the change; @code{guix refresh --list-dependent @var{package}} will help you do that (@pxref{Invoking guix refresh}). +@item +Check whether the package's build process is deterministic. This +typically means checking whether an independent build of the package +yields the exact same result that you obtained, bit for bit. + +A simple way to do that is with @command{guix challenge} +(@pxref{Invoking guix challenge}). You may run it once the package has +been committed and built by @code{hydra.gnu.org} to check whether it +obtains the same result as you did. Better yet: Find another machine +that can build it and run @command{guix publish}. + @end enumerate When posting a patch to the mailing list, use @samp{[PATCH] @dots{}} as a diff --git a/doc/guix.texi b/doc/guix.texi index 6d24343025..3222a64085 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -143,6 +143,7 @@ Utilities * Invoking guix graph:: Visualizing the graph of packages. * Invoking guix environment:: Setting up development environments. * Invoking guix publish:: Sharing substitutes. +* Invoking guix challenge:: Challenging substitute servers. GNU Distribution @@ -1600,7 +1601,10 @@ Guix has the foundations to maximize build reproducibility (@pxref{Features}). In most cases, independent builds of a given package or derivation should yield bit-identical results. Thus, through a diverse set of independent package builds, we can strengthen the -integrity of our systems. +integrity of our systems. The @command{guix challenge} command aims to +help users assess substitute servers, and to assist developers in +finding out about non-deterministic package builds (@pxref{Invoking guix +challenge}). In the future, we want Guix to have support to publish and retrieve binaries to/from other users, in a peer-to-peer fashion. If you would @@ -3577,6 +3581,7 @@ programming interface of Guix in a convenient way. * Invoking guix graph:: Visualizing the graph of packages. * Invoking guix environment:: Setting up development environments. * Invoking guix publish:: Sharing substitutes. +* Invoking guix challenge:: Challenging substitute servers. @end menu @node Invoking guix build @@ -4776,6 +4781,128 @@ Reference Manual}) on @var{port} (37146 by default). This is used primarily for debugging a running @command{guix publish} server. @end table + +@node Invoking guix challenge +@section Invoking @command{guix challenge} + +@cindex reproducible builds +@cindex verifiable builds + +Do the binaries provided by this server really correspond to the source +code it claims to build? Is this package's build process deterministic? +These are the questions the @command{guix challenge} command attempts to +answer. + +The former is obviously an important question: Before using a substitute +server (@pxref{Substitutes}), you'd rather @emph{verify} that it +provides the right binaries, and thus @emph{challenge} it. The latter +is what enables the former: If package builds are deterministic, then +independent builds of the package should yield the exact same result, +bit for bit; if a server provides a binary different from the one +obtained locally, it may be either corrupt or malicious. + +We know that the hash that shows up in @file{/gnu/store} file names is +the hash of all the inputs of the process that built the file or +directory---compilers, libraries, build scripts, +etc. (@pxref{Introduction}). Assuming deterministic build processes, +one store file name should map to exactly one build output. +@command{guix challenge} checks whether there is, indeed, a single +mapping by comparing the build outputs of several independent builds of +any given store item. + +The command's output looks like this: + +@smallexample +$ guix challenge --substitute-urls="http://hydra.gnu.org http://guix.example.org" +updating list of substitutes from 'http://hydra.gnu.org'... 100.0% +updating list of substitutes from 'http://guix.example.org'... 100.0% +/gnu/store/@dots{}-openssl-1.0.2d contents differ: + local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q + http://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q + http://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim +/gnu/store/@dots{}-git-2.5.0 contents differ: + local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha + http://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f + http://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73 +/gnu/store/@dots{}-pius-2.1.1 contents differ: + local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax + http://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax + http://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs +@end smallexample + +@noindent +In this example, @command{guix challenge} first scans the store to +determine the set of locally-built derivations---as opposed to store +items that were downloaded from a substitute server---and then queries +all the substitute servers. It then reports those store items for which +the servers obtained a result different from the local build. + +@cindex non-determinism, in package builds +As an example, @code{guix.example.org} always gets a different answer. +Conversely, @code{hydra.gnu.org} agrees with local builds, except in the +case of Git. This might indicate that the build process of Git is +non-deterministic, meaning that its output varies as a function of +various things that Guix does not fully control, in spite of building +packages in isolated environments (@pxref{Features}). Most common +sources of non-determinism include the addition of timestamps in build +results, the inclusion of random numbers, and directory listings sorted +by inode number. See @uref{http://reproducible.debian.net/howto/}, for +more information. + +To find out what's wrong with this Git binary, we can do something along +these lines (@pxref{Invoking guix archive}): + +@example +$ wget -q -O - http://hydra.gnu.org/nar/@dots{}-git-2.5.0 \ + | guix archive -x /tmp/git +$ diff -ur /gnu/store/@dots{}-git.2.5.0 /tmp/git +@end example + +This command shows the difference between the files resulting from the +local build, and the files resulting from the build on +@code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,, +diffutils, Comparing and Merging Files}). The @command{diff} command +works great for text files. When binary files differ, a better option +is @uref{http://diffoscope.org/, Diffoscope}, a tool that helps +visualize differences for all kinds of files. + +Once you've done that work, you can tell whether the differences are due +to a non-deterministic build process or to a malicious server. We try +hard to remove sources of non-determinism in packages to make it easier +to verify substitutes, but of course, this is a process, one that +involves not just Guix but a large part of the free software community. +In the meantime, @command{guix challenge} is one tool to help address +the problem. + +If you are writing packages for Guix, you are encouraged to check +whether @code{hydra.gnu.org} and other substitute servers obtain the +same build result as you did with: + +@example +$ guix challenge @var{package} +@end example + +@noindent +... where @var{package} is a package specification such as +@code{guile-2.0} or @code{glibc:debug}. + +The general syntax is: + +@example +guix challenge @var{options} [@var{packages}@dots{}] +@end example + +The one option that matters is: + +@table @code + +@item --substitute-urls=@var{urls} +Consider @var{urls} the whitespace-separated list of substitute source +URLs to compare to. + +@end table + + @c ********************************************************************* @node GNU Distribution @chapter GNU Distribution diff --git a/guix/scripts/challenge.scm b/guix/scripts/challenge.scm new file mode 100644 index 0000000000..19a9b061b8 --- /dev/null +++ b/guix/scripts/challenge.scm @@ -0,0 +1,244 @@ +;;; GNU Guix --- Functional package management for GNU +;;; Copyright © 2015 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 challenge) + #:use-module (guix ui) + #:use-module (guix scripts) + #:use-module (guix store) + #:use-module (guix utils) + #:use-module (guix monads) + #:use-module (guix base32) + #:use-module (guix packages) + #:use-module (guix serialization) + #:use-module (guix scripts substitute) + #:use-module (rnrs bytevectors) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-9) + #:use-module (srfi srfi-26) + #:use-module (srfi srfi-34) + #:use-module (srfi srfi-37) + #:use-module (ice-9 match) + #:use-module (ice-9 vlist) + #:use-module (ice-9 format) + #:use-module (web uri) + #:export (discrepancies + + discrepancy? + discrepancy-item + discrepancy-local-sha256 + discrepancy-narinfos + + guix-challenge)) + +;;; Commentary: +;;; +;;; Challenge substitute servers, checking whether they provide the same +;;; binaries as those built locally. +;;; +;;; Here we completely bypass the daemon to access substitutes. This is +;;; because we want to be able to report fine-grain information about +;;; discrepancies: We need to show the URL of the offending nar, its hash, and +;;; so on. +;;; +;;; Code: + +(define ensure-store-item ;XXX: move to (guix ui)? + (@@ (guix scripts size) ensure-store-item)) + +;; Representation of a hash mismatch for ITEM. +(define-record-type <discrepancy> + (discrepancy item local-sha256 narinfos) + discrepancy? + (item discrepancy-item) ;string, /gnu/store/… item + (local-sha256 discrepancy-local-sha256) ;bytevector | #f + (narinfos discrepancy-narinfos)) ;list of <narinfo> + +(define (locally-built? store item) + "Return true if ITEM was built locally." + ;; XXX: For now approximate it by checking whether there's a build log for + ;; ITEM. There could be false negatives, if logs have been removed. + (->bool (log-file store item))) + +(define (query-locally-built-hash item) + "Return the hash of ITEM, a store item, if ITEM was built locally. +Otherwise return #f." + (lambda (store) + (guard (c ((nix-protocol-error? c) + (values #f store))) + (if (locally-built? store item) + (values (query-path-hash store item) store) + (values #f store))))) + +(define-syntax-rule (report args ...) + (format (current-error-port) args ...)) + +(define (discrepancies items servers) + "Challenge the substitute servers whose URLs are listed in SERVERS by +comparing the hash of the substitutes of ITEMS that they serve. Return the +list of discrepancies. + +This procedure does not authenticate narinfos from SERVERS, nor does it verify +that they are signed by an authorized public keys. The reason is that, by +definition, we may want to target unknown servers. Furthermore, no risk is +taken since we do not import the archives." + (define (compare item reference) + ;; Return a procedure to compare the hash of ITEM with REFERENCE. + (lambda (narinfo url) + (if (not narinfo) + (begin + (warning (_ "~a: no substitute at '~a'~%") + item url) + #t) + (let ((value (narinfo-hash->sha256 (narinfo-hash narinfo)))) + (bytevector=? reference value))))) + + (define (select-reference item narinfos urls) + ;; Return a "reference" narinfo among NARINFOS. + (match narinfos + ((first narinfos ...) + (match servers + ((url urls ...) + (if (not first) + (select-reference item narinfos urls) + (narinfo-hash->sha256 (narinfo-hash first)))))) + (() + (leave (_ "no substitutes for '~a'~%") item)))) + + (mlet* %store-monad ((local (mapm %store-monad + query-locally-built-hash items)) + (remote -> (append-map (cut lookup-narinfos <> items) + servers)) + ;; No 'assert-valid-narinfo' on purpose. + (narinfos -> (fold (lambda (narinfo vhash) + (if narinfo + (vhash-cons (narinfo-path narinfo) narinfo + vhash) + vhash)) + vlist-null + remote))) + (return (filter-map (lambda (item local) + (let ((narinfos (vhash-fold* cons '() item narinfos))) + (define reference + (or local + (begin + (warning (_ "no local build for '~a'~%") item) + (select-reference item narinfos servers)))) + + (if (every (compare item reference) + narinfos servers) + #f + (discrepancy item local narinfos)))) + items + local)))) + +(define* (summarize-discrepancy discrepancy + #:key (hash->string + bytevector->nix-base32-string)) + "Write to the current error port a summary of DISCREPANCY, a <discrepancy> +object that denotes a hash mismatch." + (match discrepancy + (($ <discrepancy> item local (narinfos ...)) + (report (_ "~a contents differ:~%") item) + (if local + (report (_ " local hash: ~a~%") (hash->string local)) + (warning (_ "no local build for '~a'~%") item)) + + (for-each (lambda (narinfo) + (if narinfo + (report (_ " ~50a: ~a~%") + (uri->string (narinfo-uri narinfo)) + (hash->string + (narinfo-hash->sha256 (narinfo-hash narinfo)))) + (report (_ " ~50a: unavailable~%") + (uri->string (narinfo-uri narinfo))))) + narinfos)))) + + +;;; +;;; Command-line options. +;;; + +(define (show-help) + (display (_ "Usage: guix challenge [PACKAGE...] +Challenge the substitutes for PACKAGE... provided by one or more servers.\n")) + (display (_ " + --substitute-urls=URLS + compare build results with those at URLS")) + (newline) + (display (_ " + -h, --help display this help and exit")) + (display (_ " + -V, --version display version information and exit")) + (newline) + (show-bug-report-information)) + +(define %options + (list (option '(#\h "help") #f #f + (lambda args + (show-help) + (exit 0))) + (option '(#\V "version") #f #f + (lambda args + (show-version-and-exit "guix challenge"))) + + (option '("substitute-urls") #t #f + (lambda (opt name arg result . rest) + (apply values + (alist-cons 'substitute-urls + (string-tokenize arg) + (alist-delete 'substitute-urls result)) + rest))))) + +(define %default-options + `((system . ,(%current-system)) + (substitute-urls . ,%default-substitute-urls))) + + +;;; +;;; Entry point. +;;; + +(define (guix-challenge . args) + (with-error-handling + (let* ((opts (parse-command-line args %options (list %default-options))) + (files (filter-map (match-lambda + (('argument . file) file) + (_ #f)) + opts)) + (system (assoc-ref opts 'system)) + (urls (assoc-ref opts 'substitute-urls))) + (leave-on-EPIPE + (with-store store + (let ((files (match files + (() + (filter (cut locally-built? store <>) + (live-paths store))) + (x + files)))) + (set-build-options store + #:use-substitutes? #f) + + (run-with-store store + (mlet* %store-monad ((items (mapm %store-monad + ensure-store-item files)) + (issues (discrepancies items urls))) + (for-each summarize-discrepancy issues) + (return (null? issues))) + #:system system))))))) + +;;; challenge.scm ends here diff --git a/po/guix/POTFILES.in b/po/guix/POTFILES.in index af46dac0e0..d9fc04495d 100644 --- a/po/guix/POTFILES.in +++ b/po/guix/POTFILES.in @@ -22,6 +22,7 @@ guix/scripts/publish.scm guix/scripts/edit.scm guix/scripts/size.scm guix/scripts/graph.scm +guix/scripts/challenge.scm guix/gnu-maintenance.scm guix/ui.scm guix/http-client.scm diff --git a/tests/challenge.scm b/tests/challenge.scm new file mode 100644 index 0000000000..e53cacd333 --- /dev/null +++ b/tests/challenge.scm @@ -0,0 +1,114 @@ +;;; GNU Guix --- Functional package management for GNU +;;; Copyright © 2015 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 (test-challenge) + #:use-module (guix tests) + #:use-module (guix hash) + #:use-module (guix store) + #:use-module (guix monads) + #:use-module (guix derivations) + #:use-module (guix gexp) + #:use-module (guix scripts challenge) + #:use-module (guix scripts substitute) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-26) + #:use-module (srfi srfi-64) + #:use-module (rnrs bytevectors) + #:use-module (ice-9 match)) + +(define %store + (open-connection-for-tests)) + +(define query-path-hash* + (store-lift query-path-hash)) + +(define-syntax-rule (test-assertm name exp) + (test-assert name + (run-with-store %store exp + #:guile-for-build (%guile-for-build)))) + +(define* (call-with-derivation-narinfo* drv thunk hash) + (lambda (store) + (with-derivation-narinfo drv (sha256 => hash) + (values (run-with-store store (thunk)) store)))) + +(define-syntax with-derivation-narinfo* + (syntax-rules (sha256 =>) + ((_ drv (sha256 => hash) body ...) + (call-with-derivation-narinfo* drv + (lambda () body ...) + hash)))) + + +(test-begin "challenge") + +(test-assertm "no discrepancies" + (let ((text (random-text))) + (mlet* %store-monad ((drv (gexp->derivation "something" + #~(call-with-output-file + #$output + (lambda (port) + (display #$text port))))) + (out -> (derivation->output-path drv))) + (mbegin %store-monad + (built-derivations (list drv)) + (mlet %store-monad ((hash (query-path-hash* out))) + (with-derivation-narinfo* drv (sha256 => hash) + (>>= (discrepancies (list out) (%test-substitute-urls)) + (lift1 null? %store-monad)))))))) + +(test-assertm "one discrepancy" + (let ((text (random-text))) + (mlet* %store-monad ((drv (gexp->derivation "something" + #~(call-with-output-file + #$output + (lambda (port) + (display #$text port))))) + (out -> (derivation->output-path drv))) + (mbegin %store-monad + (built-derivations (list drv)) + (mlet* %store-monad ((hash (query-path-hash* out)) + (wrong-hash + -> (let* ((w (bytevector-copy hash)) + (b (bytevector-u8-ref w 0))) + (bytevector-u8-set! w 0 + (modulo (+ b 1) 128)) + w))) + (with-derivation-narinfo* drv (sha256 => wrong-hash) + (>>= (discrepancies (list out) (%test-substitute-urls)) + (match-lambda + ((discrepancy) + (return + (and (string=? out (discrepancy-item discrepancy)) + (bytevector=? hash + (discrepancy-local-sha256 + discrepancy)) + (match (discrepancy-narinfos discrepancy) + ((bad) + (bytevector=? wrong-hash + (narinfo-hash->sha256 + (narinfo-hash bad)))))))))))))))) + +(test-end) + + +(exit (= (test-runner-fail-count (test-runner-current)) 0)) + +;;; Local Variables: +;;; eval: (put 'with-derivation-narinfo* 'scheme-indent-function 2) +;;; End: |