[PATCH 0/6] Authenticated channels for everyone!

DoneSubmitted by Ludovic Courtès.
Details
4 participants
  • Kyle Meyer
  • Ludovic Courtès
  • Ricardo Wurmus
  • zimoun
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unassigned
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normal
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Ludovic Courtès wrote on 25 Jun 23:04 +0200
(address . guix-patches@gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625210400.29033-1-ludo@gnu.org
Hello Guix!
This patch series follows up on channel authentication support:
https://issues.guix.gnu.org/41767
This time the goal is to expose and document the authenticationmechanism so that third-party channel authors can use it. Thisshould be the last series on this theme in the foreseeablefuture. :-)
The most visible effect is that channel introductions are nowpart of the API and shown by ‘guix describe’. It becomes a long-termcommitment because we want to be able to pass the output of‘guix describe -C channels’ or /run/current-system/channels.scmto ‘guix pull’ and ‘guix time-machine’ in the future.
Contrary to what I initially proposed¹, channel introductions arestripped to the bare minimum: a commit/fingerprint pair (as iscurrently the case on master, internally). I figured it doesn’tbuy us much to have the commit/fingerprint pair signed; whatmatters is that users obtain the introduction from a trustedsource, and the signature wouldn’t help with that. I also gotrid of the idea of rendering introductions are opaque base64 blobs.
In the manual I tried to distinguish instructions for users(“what do I need to put in my channels.scm file?”) frominstructions for channel authors (“how do I allow users of mychannel to authenticate it?”).
If people have a channel that they’d like to make “authenticable”,please do try and report back! You can even test with master,you only need to add ‘@@’ to access (guix channels) internalsto create the introduction.
Feedback welcome!
Thanks,Ludo’.
¹ https://issues.guix.gnu.org/issue/22883#69


Ludovic Courtès (6): channels: Add 'openpgp-fingerprint->bytevector'. channels: Make channel introductions public. channels: Remove 'signature' from <channel-introduction>. channels: Save and interpret 'introduction' field in provenance data. guix describe: Display channel introductions and add 'channels-sans-intro'. services: provenance: Save channel introductions.
doc/guix.texi | 130 +++++++++++++++++++++++++++++++++++++- gnu/services.scm | 26 ++++++-- guix/channels.scm | 86 +++++++++++++++++++------ guix/scripts/describe.scm | 56 +++++++++++++--- guix/scripts/system.scm | 4 +- tests/channels.scm | 10 ++- 6 files changed, 269 insertions(+), 43 deletions(-)
-- 2.26.2
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Ludovic Courtès wrote on 25 Jun 23:16 +0200
[PATCH 1/6] channels: Add 'openpgp-fingerprint->bytevector'.
(address . 42048@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625211605.29316-1-ludo@gnu.org
* guix/channels.scm (openpgp-fingerprint->bytevector): New procedure.(openpgp-fingerprint): New macro.(%guix-channel-introduction): Use it.--- guix/channels.scm | 27 ++++++++++++++++++++++----- 1 file changed, 22 insertions(+), 5 deletions(-)
Toggle diff (54 lines)diff --git a/guix/channels.scm b/guix/channels.scmindex 3eec5df883..1d4b50aa48 100644--- a/guix/channels.scm+++ b/guix/channels.scm@@ -71,6 +71,9 @@ channel-introduction? ;; <channel-introduction> accessors purposefully omitted for now. + openpgp-fingerprint->bytevector+ openpgp-fingerprint+ %default-channels guix-channel? @@ -134,6 +137,23 @@ (first-commit-signer channel-introduction-first-commit-signer) ;bytevector (signature channel-introduction-signature)) ;string +(define (openpgp-fingerprint->bytevector str)+ "Convert STR, an OpenPGP fingerprint (hexadecimal string with whitespace),+to the corresponding bytevector."+ (base16-string->bytevector+ (string-downcase (string-filter char-set:hex-digit str))))++(define-syntax openpgp-fingerprint+ (lambda (s)+ "Convert STR, an OpenPGP fingerprint (hexadecimal string with whitespace),+to the corresponding bytevector."+ (syntax-case s ()+ ((_ str)+ (string? (syntax->datum #'str))+ (openpgp-fingerprint->bytevector (syntax->datum #'str)))+ ((_ str)+ #'(openpgp-fingerprint->bytevector str)))))+ (define %guix-channel-introduction ;; Introduction of the official 'guix channel. The chosen commit is the ;; first one that introduces '.guix-authorizations' on the 'staging'@@ -142,11 +162,8 @@ ;; & co. (make-channel-introduction "9edb3f66fd807b096b48283debdcddccfea34bad" ;2020-05-26- (base16-string->bytevector- (string-downcase- (string-filter char-set:hex-digit ;mbakke- "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA")))- #f)) ;TODO: Add an intro signature so it can be exported.+ (openpgp-fingerprint ;mbakke+ "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA"))) (define %default-channel-url ;; URL of the default 'guix' channel.-- 2.26.2
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Ludovic Courtès wrote on 25 Jun 23:16 +0200
[PATCH 2/6] channels: Make channel introductions public.
(address . 42048@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625211605.29316-2-ludo@gnu.org
* guix/channels.scm (<channel-introduction>): Rename constructor to'%make-channel-introduction'.(make-channel-introduction): New procedure.* tests/channels.scm ("authenticate-channel, wrong first commit signer")("authenticate-channel, .guix-authorizations"): Use'make-channel-introduction' without '@@' and without third argument.* doc/guix.texi (Channels)[Channel Authentication, Specifying ChannelAuthorizations]: New subsections.--- doc/guix.texi | 117 ++++++++++++++++++++++++++++++++++++++++++++- guix/channels.scm | 14 ++++-- tests/channels.scm | 10 ++-- 3 files changed, 130 insertions(+), 11 deletions(-)
Toggle diff (208 lines)diff --git a/doc/guix.texi b/doc/guix.texiindex 5b854ccbd4..a4bb52bb24 100644--- a/doc/guix.texi+++ b/doc/guix.texi@@ -3975,8 +3975,52 @@ deploys Guix itself from the official GNU@tie{}Guix repository. This can be customized by defining @dfn{channels} in the @file{~/.config/guix/channels.scm} file. A channel specifies a URL and branch of a Git repository to be deployed, and @command{guix pull} can be instructed-to pull from one or more channels. In other words, channels can be used to-@emph{customize} and to @emph{extend} Guix, as we will see below.+to pull from one or more channels. In other words, channels can be used+to @emph{customize} and to @emph{extend} Guix, as we will see below.+Before that, some security considerations.++@subsection Channel Authentication++@cindex authentication, of channel code+The @command{guix pull} and @command{guix time-machine} commands+@dfn{authenticate} the code retrieved from channels: they make sure each+commit that is fetched is signed by an authorized developer. The goal+is to protect from unauthorized modifications to the channel that would+lead users to run malicious code.++As a user, you must be @dfn{introduced} to a channel so you can start+pulling from it and authenticate its code. The @dfn{channel+introduction} tells Guix how to authenticate the first commit of that+channel:++As a user, you must provide a @dfn{channel introduction} in your+channels file so that Guix knows how to authenticate its first commit.+A channel specification, including its introduction, looks something+along these lines:++@lisp+(channel+ (name 'my-channel)+ (url "https://example.org/my-channel.git")+ (introduction+ (make-channel-introduction+ "6f0d8cc0d88abb59c324b2990bfee2876016bb86"+ (openpgp-fingerprint+ "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5"))))+@end lisp++The specification above shows the name and URL of the channel. The call+to @code{make-channel-introduction} above specifies that authentication+of this channel starts at commit @code{6f0d8cc@dots{}}, which is signed+by the OpenPGP key with fingerprint @code{CABB A931@dots{}}.++For the main channel, called @code{guix}, you automatically get that+information from your Guix installation. For other channels, include+the channel introduction provided by the channel authors in your+@file{channels.scm} file. Make sure you retrieve the channel+introduction from a trusted source since that is the root of your trust.++If you're curious about the authentication mechanics, read on! @subsection Using a Custom Guix Channel @@ -4150,6 +4194,75 @@ add a meta-data file @file{.guix-channel} that contains: (directory "guix")) @end lisp +@cindex channel authorizations+@subsection Specifying Channel Authorizations++As we saw above, Guix ensures the source code it pulls from channels+comes from authorized developers. As a channel author, you need to+specify the list of authorized developers in the+@file{.guix-authorizations} file in the channel's Git repository. The+authentication rule is simple: each commit must be signed by a key+listed in the @file{.guix-authorizations} file of its parent+commit(s)@footnote{Git commits form a @dfn{directed acyclic graph}+(DAG). Each commit can have zero or more parents; ``regular'' commits+have one parent and merge commits have two parent commits. Read+@uref{https://eagain.net/articles/git-for-computer-scientists/, @i{Git+for Computer Scientists}} for a great overview.} The+@file{.guix-authorizations} file looks like this:++@lisp+;; Example '.guix-authorizations' file.++(authorizations+ (version 0) ;current file format version++ (("AD17 A21E F8AE D8F1 CC02 DBD9 F8AE D8F1 765C 61E3"+ (name "alice"))+ ("2A39 3FFF 68F4 EF7A 3D29 12AF 68F4 EF7A 22FB B2D5"+ (name "bob"))+ ("CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5"+ (name "charlie"))))+@end lisp++Each fingerprint is followed by optional key/value pairs, as in the+example above. Currently these key/value pairs are ignored.++This authentication rule creates a chicken-and-egg issue: how do we+authenticate the first commit? Related to that: how do we deal with+channels whose repository history contains unsigned commits and lack+@file{.guix-authorizations}? And how do we fork existing channels?++@cindex channel introduction+Channel introductions answer these questions by describing the first+commit of a channel that should be authenticated. The first time a+channel is fetched with @command{guix pull} or @command{guix+time-machine}, the command looks up the introductory commit and verifies+that it is signed by the specified OpenPGP key. From then on, it+authenticates commits according to the rule above.++To summarize, as the author of a channel, there are two things you have+to do to allow users to authenticate your code:++@enumerate+@item+Introduce an initial @file{.guix-authorizations} in the channel's+repository. Do that in a signed commit (@pxref{Commit Access}, for+information on how to sign Git commits.)++@item+Advertise the channel introduction, for instance on your channel's web+page. The channel introduction, as we saw above, is the commit/key+pair---i.e., the commit that introduced @file{.guix-authorizations}, and+the fingerprint of the OpenPGP used to sign it.+@end enumerate++Publishing a signed channel requires discipline: any mistake, such as an+unsigned commit or a commit signed by an unauthorized key, will prevent+users from pulling from your channel---well, that's the whole point of+authentication! Pay attention to merges in particular: merge commits+are considered authentic if and only if they are signed by a key present+in the @file{.guix-authorizations} file of @emph{both} branches.+ @cindex primary URL, channels @subsection Primary URL diff --git a/guix/channels.scm b/guix/channels.scmindex 1d4b50aa48..9859bfdda8 100644--- a/guix/channels.scm+++ b/guix/channels.scm@@ -69,7 +69,9 @@ channel-location channel-introduction?- ;; <channel-introduction> accessors purposefully omitted for now.+ make-channel-introduction+ channel-introduction-first-signed-commit+ channel-introduction-first-commit-signer openpgp-fingerprint->bytevector openpgp-fingerprint@@ -130,13 +132,19 @@ ;; commit so that only them may emit this introduction. Introductions are ;; used to bootstrap trust in a channel. (define-record-type <channel-introduction>- (make-channel-introduction first-signed-commit first-commit-signer- signature)+ (%make-channel-introduction first-signed-commit first-commit-signer+ signature) channel-introduction? (first-signed-commit channel-introduction-first-signed-commit) ;hex string (first-commit-signer channel-introduction-first-commit-signer) ;bytevector (signature channel-introduction-signature)) ;string +(define (make-channel-introduction commit signer)+ "Return a new channel introduction: COMMIT is the introductory where+authentication starts, and SIGNER is the OpenPGP fingerprint (a bytevector) of+the signer of that commit."+ (%make-channel-introduction commit signer #f))+ (define (openpgp-fingerprint->bytevector str) "Convert STR, an OpenPGP fingerprint (hexadecimal string with whitespace), to the corresponding bytevector."diff --git a/tests/channels.scm b/tests/channels.scmindex 3a2c1d429b..016c3ad9db 100644--- a/tests/channels.scm+++ b/tests/channels.scm@@ -430,12 +430,11 @@ (with-repository directory repository (let* ((commit1 (find-commit repository "first")) (commit2 (find-commit repository "second"))- (intro ((@@ (guix channels) make-channel-introduction)+ (intro (make-channel-introduction (commit-id-string commit1) (openpgp-public-key-fingerprint (read-openpgp-packet- %ed25519bis-public-key-file)) ;different key- #f)) ;no signature+ %ed25519bis-public-key-file)))) ;different key (channel (channel (name 'example) (url (string-append "file://" directory)) (introduction intro))))@@ -486,12 +485,11 @@ (let* ((commit1 (find-commit repository "first")) (commit2 (find-commit repository "second")) (commit3 (find-commit repository "third"))- (intro ((@@ (guix channels) make-channel-introduction)+ (intro (make-channel-introduction (commit-id-string commit1) (openpgp-public-key-fingerprint (read-openpgp-packet- %ed25519-public-key-file))- #f)) ;no signature+ %ed25519-public-key-file)))) (channel (channel (name 'example) (url (string-append "file://" directory)) (introduction intro))))-- 2.26.2
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Ludovic Courtès wrote on 25 Jun 23:16 +0200
[PATCH 3/6] channels: Remove 'signature' from <channel-introduction>.
(address . 42048@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625211605.29316-3-ludo@gnu.org
In the end signing the commit/key pair does not buy us much. Someonepublishing a valid but different commit/key pair would effectively bepublishing a different channel, which could be a fork (made by a formerauthorized developer) or simply a mirror. In the latter case, there'snothing to be gained by publishing a different commit/key pair.
* guix/channels.scm (<channel-introduction>)[signature]: Remove.(make-channel-introduction): Adjust accordingly.--- guix/channels.scm | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)
Toggle diff (35 lines)diff --git a/guix/channels.scm b/guix/channels.scmindex 9859bfdda8..05b2661445 100644--- a/guix/channels.scm+++ b/guix/channels.scm@@ -128,22 +128,19 @@ ;; Channel introductions. A "channel introduction" provides a commit/signer ;; pair that specifies the first commit of the authentication process as well-;; as its signer's fingerprint. The pair must be signed by the signer of that-;; commit so that only them may emit this introduction. Introductions are-;; used to bootstrap trust in a channel.+;; as its signer's fingerprint. Introductions are used to bootstrap trust in+;; a channel. (define-record-type <channel-introduction>- (%make-channel-introduction first-signed-commit first-commit-signer- signature)+ (%make-channel-introduction first-signed-commit first-commit-signer) channel-introduction?- (first-signed-commit channel-introduction-first-signed-commit) ;hex string- (first-commit-signer channel-introduction-first-commit-signer) ;bytevector- (signature channel-introduction-signature)) ;string+ (first-signed-commit channel-introduction-first-signed-commit) ;hex string+ (first-commit-signer channel-introduction-first-commit-signer)) ;bytevector (define (make-channel-introduction commit signer) "Return a new channel introduction: COMMIT is the introductory where authentication starts, and SIGNER is the OpenPGP fingerprint (a bytevector) of the signer of that commit."- (%make-channel-introduction commit signer #f))+ (%make-channel-introduction commit signer)) (define (openpgp-fingerprint->bytevector str) "Convert STR, an OpenPGP fingerprint (hexadecimal string with whitespace),-- 2.26.2
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Ludovic Courtès wrote on 25 Jun 23:16 +0200
[PATCH 4/6] channels: Save and interpret 'introduction' field in provenance data.
(address . 42048@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625211605.29316-4-ludo@gnu.org
With this change, profiles created by 'guix pull' & co. include channelintroductions as part of the channel metadata of each manifest entry.
* guix/channels.scm (channel-instances->manifest)[instance->entry]: Add'introduction' field when CHANNEL has an introduction.(profile-channels)[sexp->channel-introduction]: New procedure.Use it to initialize the 'introduction' field.--- guix/channels.scm | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-)
Toggle diff (72 lines)diff --git a/guix/channels.scm b/guix/channels.scmindex 05b2661445..02800733dd 100644--- a/guix/channels.scm+++ b/guix/channels.scm@@ -844,8 +844,9 @@ derivation." "Return a profile manifest with entries for all of INSTANCES, a list of channel instances." (define (instance->entry instance drv)- (let ((commit (channel-instance-commit instance))- (channel (channel-instance-channel instance)))+ (let* ((commit (channel-instance-commit instance))+ (channel (channel-instance-channel instance))+ (intro (channel-introduction channel))) (manifest-entry (name (symbol->string (channel-name channel))) (version (string-take commit 7))@@ -860,7 +861,19 @@ channel instances." (version 0) (url ,(channel-url channel)) (branch ,(channel-branch channel))- (commit ,commit))))))))+ (commit ,commit)+ ,@(if intro+ `((introduction+ (channel-introduction+ (version 0)+ (commit+ ,(channel-introduction-first-signed-commit+ intro))+ (signer+ ,(openpgp-format-fingerprint+ (channel-introduction-first-commit-signer+ intro))))))+ '())))))))) (mlet* %store-monad ((derivations (channel-instance-derivations instances)) (entries -> (map instance->entry instances derivations)))@@ -928,17 +941,30 @@ to 'latest-channel-instances'." (define (profile-channels profile) "Return the list of channels corresponding to entries in PROFILE. If PROFILE is not a profile created by 'guix pull', return the empty list."+ (define sexp->channel-introduction+ (match-lambda+ (('channel-introduction ('version 0)+ ('commit commit) ('signer signer)+ _ ...)+ (make-channel-introduction commit (openpgp-fingerprint signer)))+ (x #f)))+ (filter-map (lambda (entry) (match (assq 'source (manifest-entry-properties entry)) (('source ('repository ('version 0) ('url url) ('branch branch) ('commit commit)- _ ...))+ rest ...)) (channel (name (string->symbol (manifest-entry-name entry))) (url url)- (commit commit)))+ (commit commit)+ (introduction+ (match (assq 'introduction rest)+ (#f #f)+ (('introduction intro)+ (sexp->channel-introduction intro)))))) ;; No channel information for this manifest entry. ;; XXX: Pre-0.15.0 Guix did not provide that information,-- 2.26.2
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Ludovic Courtès wrote on 25 Jun 23:16 +0200
[PATCH 5/6] guix describe: Display channel introductions and add 'channels-sans-intro'.
(address . 42048@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625211605.29316-5-ludo@gnu.org
* guix/scripts/describe.scm (%available-formats): Add "channels-sans-intro".(channel->sexp): Add #:include-introduction?. Emit CHANNEL's intro ifINCLUDE-INTRODUCTION? is true and CHANNEL has an introduction.(channel->json): Include CHANNEL's introduction, if any.(channel->recutils): Likewise.(display-profile-info): Add 'channels-sans-intro' case.* doc/guix.texi (Invoking guix describe): Add introduction in example.Add 'channels-sans-intro' case.--- doc/guix.texi | 13 ++++++++- guix/scripts/describe.scm | 56 ++++++++++++++++++++++++++++++++------- 2 files changed, 58 insertions(+), 11 deletions(-)
Toggle diff (130 lines)diff --git a/doc/guix.texi b/doc/guix.texiindex a4bb52bb24..fcf67bd718 100644--- a/doc/guix.texi+++ b/doc/guix.texi@@ -4613,7 +4613,12 @@ $ guix describe -f channels (name 'guix) (url "https://git.savannah.gnu.org/git/guix.git") (commit- "e0fa68c7718fffd33d81af415279d6ddb518f727")))+ "e0fa68c7718fffd33d81af415279d6ddb518f727")+ (introduction+ (make-channel-introduction+ "9edb3f66fd807b096b48283debdcddccfea34bad"+ (openpgp-fingerprint+ "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA"))))) @end example @noindent@@ -4639,6 +4644,12 @@ produce human-readable output; produce a list of channel specifications that can be passed to @command{guix pull -C} or installed as @file{~/.config/guix/channels.scm} (@pxref{Invoking guix pull});+@item channels-sans-intro+like @code{channels}, but omit the @code{introduction} field; use it to+produce a channel specification suitable for Guix version 1.1.0 or+earlier---the @code{introduction} field has to do with channel+authentication (@pxref{Channels, Channel Authentication}) and is not+supported by these older versions; @item json @cindex JSON produce a list of channel specifications in JSON format;diff --git a/guix/scripts/describe.scm b/guix/scripts/describe.scmindex 7a2dbc453a..39e096a9a4 100644--- a/guix/scripts/describe.scm+++ b/guix/scripts/describe.scm@@ -26,9 +26,11 @@ #:use-module (guix scripts) #:use-module (guix describe) #:use-module (guix profiles)+ #:autoload (guix openpgp) (openpgp-format-fingerprint) #:use-module (git) #:use-module (json) #:use-module (srfi srfi-1)+ #:use-module (srfi srfi-26) #:use-module (srfi srfi-37) #:use-module (ice-9 match) #:autoload (ice-9 pretty-print) (pretty-print)@@ -42,7 +44,8 @@ ;;; ;;; Command-line options. ;;;-(define %available-formats '("human" "channels" "json" "recutils"))+(define %available-formats+ '("human" "channels" "channels-sans-intro" "json" "recutils")) (define (list-formats) (display (G_ "The available formats are:\n"))@@ -109,21 +112,50 @@ Display information about the channels currently in use.\n")) (_ (warning (G_ "'GUIX_PACKAGE_PATH' is set but it is not captured~%"))))))) -(define (channel->sexp channel)- `(channel- (name ',(channel-name channel))- (url ,(channel-url channel))- (commit ,(channel-commit channel))))+(define* (channel->sexp channel #:key (include-introduction? #t))+ (let ((intro (and include-introduction?+ (channel-introduction channel))))+ `(channel+ (name ',(channel-name channel))+ (url ,(channel-url channel))+ (commit ,(channel-commit channel))+ ,@(if intro+ `((introduction (make-channel-introduction+ ,(channel-introduction-first-signed-commit intro)+ (openpgp-fingerprint+ ,(openpgp-format-fingerprint+ (channel-introduction-first-commit-signer+ intro))))))+ '())))) (define (channel->json channel)- (scm->json-string `((name . ,(channel-name channel))- (url . ,(channel-url channel))- (commit . ,(channel-commit channel)))))+ (scm->json-string+ (let ((intro (channel-introduction channel)))+ `((name . ,(channel-name channel))+ (url . ,(channel-url channel))+ (commit . ,(channel-commit channel))+ ,@(if intro+ `((introduction+ . ((commit . ,(channel-introduction-first-signed-commit+ intro))+ (signer . ,(openpgp-format-fingerprint+ (channel-introduction-first-commit-signer+ intro))))))+ '()))))) (define (channel->recutils channel port)+ (define intro+ (channel-introduction channel))+ (format port "name: ~a~%" (channel-name channel)) (format port "url: ~a~%" (channel-url channel))- (format port "commit: ~a~%" (channel-commit channel)))+ (format port "commit: ~a~%" (channel-commit channel))+ (when intro+ (format port "introductioncommit: ~a~%"+ (channel-introduction-first-signed-commit intro))+ (format port "introductionsigner: ~a~%"+ (openpgp-format-fingerprint+ (channel-introduction-first-commit-signer intro))))) (define (display-checkout-info fmt) "Display information about the current checkout according to FMT, a symbol@@ -181,6 +213,10 @@ in the format specified by FMT." (display-profile-content profile number)) ('channels (pretty-print `(list ,@(map channel->sexp channels))))+ ('channels-sans-intro+ (pretty-print `(list ,@(map (cut channel->sexp <>+ #:include-introduction? #f)+ channels)))) ('json (format #t "[~a]~%" (string-join (map channel->json channels) ","))) ('recutils-- 2.26.2
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Ludovic Courtès wrote on 25 Jun 23:16 +0200
[PATCH 6/6] services: provenance: Save channel introductions.
(address . 42048@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)
20200625211605.29316-6-ludo@gnu.org
* gnu/services.scm (channel->code): Include CHANNEL's introduction, ifany, unless CHANNEL is the singleton %DEFAULT-CHANNELS.(channel->sexp): Add comment.* guix/scripts/system.scm (sexp->channel): Change pattern to allow forextensibility.--- gnu/services.scm | 26 ++++++++++++++++++++++---- guix/scripts/system.scm | 4 +++- 2 files changed, 25 insertions(+), 5 deletions(-)
Toggle diff (65 lines)diff --git a/gnu/services.scm b/gnu/services.scmindex 27e5558231..f6dc56d940 100644--- a/gnu/services.scm+++ b/gnu/services.scm@@ -31,6 +31,7 @@ #:use-module (guix sets) #:use-module (guix ui) #:use-module ((guix utils) #:select (source-properties->location))+ #:autoload (guix openpgp) (openpgp-format-fingerprint) #:use-module (guix modules) #:use-module (gnu packages base) #:use-module (gnu packages bash)@@ -392,14 +393,31 @@ by the initrd once the root file system is mounted."))) (define (channel->code channel) "Return code to build CHANNEL, ready to be dropped in a 'channels.scm' file."- `(channel (name ',(channel-name channel))- (url ,(channel-url channel))- (branch ,(channel-branch channel))- (commit ,(channel-commit channel))))+ ;; Since the 'introduction' field is backward-incompatible, and since it's+ ;; optional when using the "official" 'guix channel, include it if and only+ ;; if we're referring to a different channel.+ (let ((intro (and (not (equal? (list channel) %default-channels))+ (channel-introduction channel))))+ `(channel (name ',(channel-name channel))+ (url ,(channel-url channel))+ (branch ,(channel-branch channel))+ (commit ,(channel-commit channel))+ ,@(if intro+ `((introduction+ (make-channel-introduction+ ,(channel-introduction-first-signed-commit intro)+ (openpgp-fingerprint+ ,(openpgp-format-fingerprint+ (channel-introduction-first-commit-signer+ intro))))))+ '())))) (define (channel->sexp channel) "Return an sexp describing CHANNEL. The sexp is _not_ code and is meant to be parsed by tools; it's potentially more future-proof than code."+ ;; TODO: Add CHANNEL's introduction. Currently we can't do that because+ ;; older 'guix system describe' expect exactly name/url/branch/commit+ ;; without any additional fields. `(channel (name ,(channel-name channel)) (url ,(channel-url channel)) (branch ,(channel-branch channel))diff --git a/guix/scripts/system.scm b/guix/scripts/system.scmindex 212b49f008..cfefe8a8a8 100644--- a/guix/scripts/system.scm+++ b/guix/scripts/system.scm@@ -452,7 +452,9 @@ list of services." (('channel ('name name) ('url url) ('branch branch)- ('commit commit))+ ('commit commit)+ rest ...)+ ;; XXX: In the future REST may include a channel introduction. (channel (name name) (url url) (branch branch) (commit commit))))) -- 2.26.2
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Kyle Meyer wrote on 26 Jun 00:32 +0200
Re: [bug#42048] [PATCH 2/6] channels: Make channel introductions public.
(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 42048@debbugs.gnu.org)
87h7uy7p57.fsf@kyleam.com
Ludovic Courtès writes:
Toggle quote (1 lines)> diff --git a/doc/guix.texi b/doc/guix.texi
[...]
Toggle quote (5 lines)> +As a user, you must be @dfn{introduced} to a channel so you can start> +pulling from it and authenticate its code. The @dfn{channel> +introduction} tells Guix how to authenticate the first commit of that> +channel:
Given the colon, it looks like something is missing here. Based on whatcomes next...
Toggle quote (17 lines)> +> +As a user, you must provide a @dfn{channel introduction} in your> +channels file so that Guix knows how to authenticate its first commit.> +A channel specification, including its introduction, looks something> +along these lines:> +> +@lisp> +(channel> + (name 'my-channel)> + (url "https://example.org/my-channel.git")> + (introduction> + (make-channel-introduction> + "6f0d8cc0d88abb59c324b2990bfee2876016bb86"> + (openpgp-fingerprint> + "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5"))))> +@end lisp
... perhaps the second "As a user" paragraph was supposed to replace thefirst?
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Ludovic Courtès wrote on 26 Jun 10:17 +0200
(name . Kyle Meyer)(address . kyle@kyleam.com)(address . 42048@debbugs.gnu.org)
87y2oansv2.fsf@gnu.org
Hello Kyle,
Kyle Meyer <kyle@kyleam.com> skribis:
Toggle quote (32 lines)> Ludovic Courtès writes:>>> diff --git a/doc/guix.texi b/doc/guix.texi> [...]>> +As a user, you must be @dfn{introduced} to a channel so you can start>> +pulling from it and authenticate its code. The @dfn{channel>> +introduction} tells Guix how to authenticate the first commit of that>> +channel:>> Given the colon, it looks like something is missing here. Based on what> comes next...>>> +>> +As a user, you must provide a @dfn{channel introduction} in your>> +channels file so that Guix knows how to authenticate its first commit.>> +A channel specification, including its introduction, looks something>> +along these lines:>> +>> +@lisp>> +(channel>> + (name 'my-channel)>> + (url "https://example.org/my-channel.git")>> + (introduction>> + (make-channel-introduction>> + "6f0d8cc0d88abb59c324b2990bfee2876016bb86">> + (openpgp-fingerprint>> + "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5"))))>> +@end lisp>> ... perhaps the second "As a user" paragraph was supposed to replace the> first?
Oops, thanks for the heads-up. I guess I got distracted as I wasreorganizing this. I’ll post a v2 soonish!
Ludo’.
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Ludovic Courtès wrote on 27 Jun 19:07 +0200
(name . Kyle Meyer)(address . kyle@kyleam.com)(address . 42048@debbugs.gnu.org)
87v9jcl9ob.fsf@gnu.org
Kyle Meyer <kyle@kyleam.com> skribis:
Toggle quote (32 lines)> Ludovic Courtès writes:>>> diff --git a/doc/guix.texi b/doc/guix.texi> [...]>> +As a user, you must be @dfn{introduced} to a channel so you can start>> +pulling from it and authenticate its code. The @dfn{channel>> +introduction} tells Guix how to authenticate the first commit of that>> +channel:>> Given the colon, it looks like something is missing here. Based on what> comes next...>>> +>> +As a user, you must provide a @dfn{channel introduction} in your>> +channels file so that Guix knows how to authenticate its first commit.>> +A channel specification, including its introduction, looks something>> +along these lines:>> +>> +@lisp>> +(channel>> + (name 'my-channel)>> + (url "https://example.org/my-channel.git")>> + (introduction>> + (make-channel-introduction>> + "6f0d8cc0d88abb59c324b2990bfee2876016bb86">> + (openpgp-fingerprint>> + "CABB A931 C0FF EEC6 900D 0CFB 090B 1199 3D9A EBB5"))))>> +@end lisp>> ... perhaps the second "As a user" paragraph was supposed to replace the> first?
Yes, you were right. I’ve changed it locally (not resending the wholeseries).
Thanks!
Ludo’.
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Ricardo Wurmus wrote on 30 Jun 16:35 +0200
Re: [bug#42048] [PATCH 3/6] channels: Remove 'signature' from <channel-introduction>.
(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 42048@debbugs.gnu.org)
871rlwoc4d.fsf@elephly.net
Ludovic Courtès <ludo@gnu.org> writes:
Toggle quote (9 lines)> In the end signing the commit/key pair does not buy us much. Someone> publishing a valid but different commit/key pair would effectively be> publishing a different channel, which could be a fork (made by a former> authorized developer) or simply a mirror. In the latter case, there's> nothing to be gained by publishing a different commit/key pair.>> * guix/channels.scm (<channel-introduction>)[signature]: Remove.> (make-channel-introduction): Adjust accordingly.> ---
[…]
Toggle quote (7 lines)> (define (make-channel-introduction commit signer)> "Return a new channel introduction: COMMIT is the introductory where> authentication starts, and SIGNER is the OpenPGP fingerprint (a bytevector) of> the signer of that commit."> - (%make-channel-introduction commit signer #f))> + (%make-channel-introduction commit signer))
Do we still need this procedure at all? Looks like%make-channel-introduction could simply be renamed to make-channel-introduction.
-- Ricardo
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Ludovic Courtès wrote on 30 Jun 17:15 +0200
(name . Ricardo Wurmus)(address . rekado@elephly.net)(address . 42048@debbugs.gnu.org)
87ftac60ur.fsf@gnu.org
Hi,
Ricardo Wurmus <rekado@elephly.net> skribis:
Toggle quote (22 lines)> Ludovic Courtès <ludo@gnu.org> writes:>>> In the end signing the commit/key pair does not buy us much. Someone>> publishing a valid but different commit/key pair would effectively be>> publishing a different channel, which could be a fork (made by a former>> authorized developer) or simply a mirror. In the latter case, there's>> nothing to be gained by publishing a different commit/key pair.>>>> * guix/channels.scm (<channel-introduction>)[signature]: Remove.>> (make-channel-introduction): Adjust accordingly.>> ---> […]>> (define (make-channel-introduction commit signer)>> "Return a new channel introduction: COMMIT is the introductory where>> authentication starts, and SIGNER is the OpenPGP fingerprint (a bytevector) of>> the signer of that commit.">> - (%make-channel-introduction commit signer #f))>> + (%make-channel-introduction commit signer))>> Do we still need this procedure at all? Looks like> %make-channel-introduction could simply be renamed to make-channel-introduction.
‘%make-channel-introduction’ is actually a macro, which is thus inlined.Exporting a procedure makes it easier to preserve ABI compatibility andallow for future extensions (keyword parameters, for instance).
Ludo’.
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Ricardo Wurmus wrote on 30 Jun 17:53 +0200
Re: [bug#42048] [PATCH 6/6] services: provenance: Save channel introductions.
(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 42048@debbugs.gnu.org)
87v9j8mtx9.fsf@elephly.net
I looked through the changes and while I don’t fully understand the needfor adding the introduction to the provenance data, it looks good tome. Thank you!
One thing that I worry about is authentication of channels that areadded as dependencies of user-selected channels. Let’s say my channel“guix-bimsb” depends on “guix-past”. How will users of “guix-bimsb”authenticate the commits of “guix-past” when they don’t know about“guix-past” (they only care about “guix-bimsb”), and don’t explicitlyadd introduction information to their channels file?
Is there something that the authors of “guix-bimsb” can do to not onlyindicate the dependency on “guix-past”, but also to attach introductioninformation? Will the format of the “.guix-channel” need to beadjusted?
-- Ricardo
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Ludovic Courtès wrote on 30 Jun 22:28 +0200
(name . Ricardo Wurmus)(address . rekado@elephly.net)(address . 42048@debbugs.gnu.org)
87imf847sr.fsf@gnu.org
Hi Ricardo,
Ricardo Wurmus <rekado@elephly.net> skribis:
Toggle quote (4 lines)> I looked through the changes and while I don’t fully understand the need> for adding the introduction to the provenance data, it looks good to> me. Thank you!
Overall the idea is that a channel spec should always come with itsintroduction; together they identify the channel and thus should not beseparated.
Adding the introduction to the provenance data allows ‘guix describe’ toshow the introduction, to ensure it’s not lost in transit.
Does that make sense?
Toggle quote (12 lines)> One thing that I worry about is authentication of channels that are> added as dependencies of user-selected channels. Let’s say my channel> “guix-bimsb” depends on “guix-past”. How will users of “guix-bimsb”> authenticate the commits of “guix-past” when they don’t know about> “guix-past” (they only care about “guix-bimsb”), and don’t explicitly> add introduction information to their channels file?>> Is there something that the authors of “guix-bimsb” can do to not only> indicate the dependency on “guix-past”, but also to attach introduction> information? Will the format of the “.guix-channel” need to be> adjusted?
That’s a very good question and I had completely overlooked it.
With this patch set, someone pulling guix-bimsb would just end uppulling guix-past unauthenticated; there’s not even a warning.
(There’s currently a warning in (guix channels), but only when pullingan unauthenticated 'guix channel. It’s perhaps too early to have thatwarning enabled for all channels. WDYT?)
So yes, I suppose we would need to extend the ‘.guix-channel’ format fordependencies. Luckily it should be quite simply because that format isextensible; older Guix versions would ignore the ‘introduction’ field.It would look something like this:
(channel (version 0) (dependencies (channel (name some-collection) (url "https://example.org/first-collection.git") (introduction (channel-introduction (version 0) (commit "…") (signer "…")))) (channel (name some-other-collection) (url "https://example.org/second-collection.git") (branch "testing")))) ;not an authenticated channel
It does mean that a channel can indirectly trick you into turning offauthentication for a dependent channel. But I think that’s within theexpectations for channels: when you choose a channel, you trust itenough to run its code.
WDYT?
Thanks for reviewing!
Ludo’.
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zimoun wrote on 1 Jul 10:51 +0200
(address . 42048@debbugs.gnu.org)
86lfk3aa9p.fsf@gmail.com
Hi,
On Tue, 30 Jun 2020 at 22:28, Ludovic Courtès <ludo@gnu.org> wrote:
Toggle quote (14 lines)>> One thing that I worry about is authentication of channels that are>> added as dependencies of user-selected channels. Let’s say my channel>> “guix-bimsb” depends on “guix-past”. How will users of “guix-bimsb”>> authenticate the commits of “guix-past” when they don’t know about>> “guix-past” (they only care about “guix-bimsb”), and don’t explicitly>> add introduction information to their channels file?>>>> Is there something that the authors of “guix-bimsb” can do to not only>> indicate the dependency on “guix-past”, but also to attach introduction>> information? Will the format of the “.guix-channel” need to be>> adjusted?>> That’s a very good question and I had completely overlooked it.
Héhé, yet I had the same question one month ago. :-)
Toggle snippet (14 lines)> The question about recursive still applies. ;-)> Currently, if the local channel file points to a channel A which> contains the file '.guix-channel' which points to another channel B,> then when one runs "guix pull" well the channel A will be pulled and> then the channel B, even if this channel B is not explicit in the> initial local channel. (Even, there is bug about recursive implicit> pulls, see http://issues.guix.gnu.org/issue/41069; well another> story.)>What happens for such situation?
Nothing special, I guess: each channel would be authenticated (or not,ifit’s an unsigned channel). I think it’s completely orthogonal.
Toggle quote (7 lines)> With this patch set, someone pulling guix-bimsb would just end up> pulling guix-past unauthenticated; there’s not even a warning.>> (There’s currently a warning in (guix channels), but only when pulling> an unauthenticated 'guix channel. It’s perhaps too early to have that> warning enabled for all channels. WDYT?)
Enable the warning appears to me a good idea because this dependency islike "doing something I am not necessary aware in my back".
For example, the first time I pulled the channel "guix-bimsb-non-free" whichdepends on "guix-bimsb", it took me some time to understand why"guix-bimsb" was pulled twice and once with a name I do not have in mylocal channels.scm file. Anyway.
Toggle quote (25 lines)> So yes, I suppose we would need to extend the ‘.guix-channel’ format for> dependencies. Luckily it should be quite simply because that format is> extensible; older Guix versions would ignore the ‘introduction’ field.> It would look something like this:>> (channel> (version 0)> (dependencies> (channel> (name some-collection)> (url "https://example.org/first-collection.git")> (introduction (channel-introduction> (version 0)> (commit "…")> (signer "…"))))> (channel> (name some-other-collection)> (url "https://example.org/second-collection.git")> (branch "testing")))) ;not an authenticated channel>> It does mean that a channel can indirectly trick you into turning off> authentication for a dependent channel. But I think that’s within the> expectations for channels: when you choose a channel, you trust it> enough to run its code.
Sound good to me.
When I choose a channel, I trust the people enough to run their code.But I do not trust the URL which serves it. I mean, it is the point ofall this new authentication mechanism, isn't it?
However, I agree. Channel should stay easy to fork and add something(then maybe send a pull-request) without going in all the GPG signaturedance and/or running the options --allow-downgrades or--disable-authentication (I do not remember the exact name).

Cheers,simon
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zimoun wrote on 1 Jul 11:35 +0200
Re: [bug#42048] [PATCH 0/6] Authenticated channels for everyone!
(name . Ludovic Courtès)(address . ludo@gnu.org)
86ftaba874.fsf@gmail.com
Hi Ludo,
On Thu, 25 Jun 2020 at 23:04, Ludovic Courtès <ludo@gnu.org> wrote:
Toggle quote (6 lines)> The most visible effect is that channel introductions are now> part of the API and shown by ‘guix describe’. It becomes a long-term> commitment because we want to be able to pass the output of> ‘guix describe -C channels’ or /run/current-system/channels.scm> to ‘guix pull’ and ‘guix time-machine’ in the future.
How could I test this machinery with "guix time-machine"?
Toggle quote (8 lines)> Contrary to what I initially proposed¹, channel introductions are> stripped to the bare minimum: a commit/fingerprint pair (as is> currently the case on master, internally). I figured it doesn’t> buy us much to have the commit/fingerprint pair signed; what> matters is that users obtain the introduction from a trusted> source, and the signature wouldn’t help with that. I also got> rid of the idea of rendering introductions are opaque base64 blobs.
What happens when traveling in time if the key used by the signature hasbeen compromised?
Today, everything is fine, I sign and I do in introduction. Couple ofmonths (or even years) later, my key will be compromised and so I willrevoke it. What happens if I do "guix time-machine -C"?
Well, the question even applies to %default-channel? Maybe you alreadyanswered and I missed it.

Cheers,simon
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Ludovic Courtès wrote on 1 Jul 14:12 +0200
Re: [bug#42048] [PATCH 6/6] services: provenance: Save channel introductions.
(name . zimoun)(address . zimon.toutoune@gmail.com)
87r1tvzb6s.fsf@gnu.org
Hi Simon,
zimoun <zimon.toutoune@gmail.com> skribis:
Toggle quote (18 lines)> On Tue, 30 Jun 2020 at 22:28, Ludovic Courtès <ludo@gnu.org> wrote:>>>> One thing that I worry about is authentication of channels that are>>> added as dependencies of user-selected channels. Let’s say my channel>>> “guix-bimsb” depends on “guix-past”. How will users of “guix-bimsb”>>> authenticate the commits of “guix-past” when they don’t know about>>> “guix-past” (they only care about “guix-bimsb”), and don’t explicitly>>> add introduction information to their channels file?>>>>>> Is there something that the authors of “guix-bimsb” can do to not only>>> indicate the dependency on “guix-past”, but also to attach introduction>>> information? Will the format of the “.guix-channel” need to be>>> adjusted?>>>> That’s a very good question and I had completely overlooked it.>> Héhé, yet I had the same question one month ago. :-)
Oh I’m sorry, I think I misunderstood your question back then!
Toggle quote (10 lines)>> With this patch set, someone pulling guix-bimsb would just end up>> pulling guix-past unauthenticated; there’s not even a warning.>>>> (There’s currently a warning in (guix channels), but only when pulling>> an unauthenticated 'guix channel. It’s perhaps too early to have that>> warning enabled for all channels. WDYT?)>> Enable the warning appears to me a good idea because this dependency is> like "doing something I am not necessary aware in my back".
I’m talking about the warning that says “this channel isunauthenticated”, which is mostly orthogonal to the discussion at hand.The reason I said it’s perhaps too early to enable it is that peoplehaven’t had a chance to make their channel “authenticable” yet.
Toggle quote (27 lines)>> So yes, I suppose we would need to extend the ‘.guix-channel’ format for>> dependencies. Luckily it should be quite simply because that format is>> extensible; older Guix versions would ignore the ‘introduction’ field.>> It would look something like this:>>>> (channel>> (version 0)>> (dependencies>> (channel>> (name some-collection)>> (url "https://example.org/first-collection.git")>> (introduction (channel-introduction>> (version 0)>> (commit "…")>> (signer "…"))))>> (channel>> (name some-other-collection)>> (url "https://example.org/second-collection.git")>> (branch "testing")))) ;not an authenticated channel>>>> It does mean that a channel can indirectly trick you into turning off>> authentication for a dependent channel. But I think that’s within the>> expectations for channels: when you choose a channel, you trust it>> enough to run its code.>> Sound good to me.
Alright, I’ll do that as a followup.
Thanks!
Ludo’.
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Ludovic Courtès wrote on 1 Jul 14:17 +0200
Re: [bug#42048] [PATCH 0/6] Authenticated channels for everyone!
(name . zimoun)(address . zimon.toutoune@gmail.com)(address . 42048@debbugs.gnu.org)
87a70jzaxd.fsf@gnu.org
Hi,
zimoun <zimon.toutoune@gmail.com> skribis:
Toggle quote (10 lines)> On Thu, 25 Jun 2020 at 23:04, Ludovic Courtès <ludo@gnu.org> wrote:>>> The most visible effect is that channel introductions are now>> part of the API and shown by ‘guix describe’. It becomes a long-term>> commitment because we want to be able to pass the output of>> ‘guix describe -C channels’ or /run/current-system/channels.scm>> to ‘guix pull’ and ‘guix time-machine’ in the future.>> How could I test this machinery with "guix time-machine"?
The normal way. :-)
But of course, the new ‘introduction’ field of <channel> won’t berecognized by older Guix versions. In that case, you should use theoutput of ‘guix describe -f channels-sans-intro’ as I wrote in themanual.
Toggle quote (11 lines)>> Contrary to what I initially proposed¹, channel introductions are>> stripped to the bare minimum: a commit/fingerprint pair (as is>> currently the case on master, internally). I figured it doesn’t>> buy us much to have the commit/fingerprint pair signed; what>> matters is that users obtain the introduction from a trusted>> source, and the signature wouldn’t help with that. I also got>> rid of the idea of rendering introductions are opaque base64 blobs.>> What happens when traveling in time if the key used by the signature has> been compromised?
In general, when a developer loses control over their key, anothercommitter should remove it right away form ‘.guix-authorizations’. (Idid that today following Brett’s message, for example.)
Signatures on past commits can still be verified and everything is fine.The (guix openpgp) code ignores key expiration and revocation; it “just”verifies signatures.
Toggle quote (4 lines)> Today, everything is fine, I sign and I do in introduction. Couple of> months (or even years) later, my key will be compromised and so I will> revoke it. What happens if I do "guix time-machine -C"?
That’s OK. The keyring is distributed along with the channel stillcontains your key, with or without a revocation certificate, but thatdoesn’t prevent us from verifying signatures on past commits. (This isdifferent from what gpg does.)
Ludo’.
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Ricardo Wurmus wrote on 1 Jul 14:25 +0200
Re: [bug#42048] [PATCH 6/6] services: provenance: Save channel introductions.
(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 42048@debbugs.gnu.org)
87366bmnhb.fsf@elephly.net
Ludovic Courtès <ludo@gnu.org> writes:
Toggle quote (27 lines)> So yes, I suppose we would need to extend the ‘.guix-channel’ format for> dependencies. Luckily it should be quite simply because that format is> extensible; older Guix versions would ignore the ‘introduction’ field.> It would look something like this:>> (channel> (version 0)> (dependencies> (channel> (name some-collection)> (url "https://example.org/first-collection.git")> (introduction (channel-introduction> (version 0)> (commit "…")> (signer "…"))))> (channel> (name some-other-collection)> (url "https://example.org/second-collection.git")> (branch "testing")))) ;not an authenticated channel>> It does mean that a channel can indirectly trick you into turning off> authentication for a dependent channel. But I think that’s within the> expectations for channels: when you choose a channel, you trust it> enough to run its code.>> WDYT?
This sounds reasonable. I agree that you’ve got to trust the channelauthors anyway, so allowing them to provide the introduction is fair.
-- Ricardo
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zimoun wrote on 1 Jul 14:49 +0200
(name . Ludovic Courtès)(address . ludo@gnu.org)
86d05f9z94.fsf@gmail.com
On Wed, 01 Jul 2020 at 14:12, Ludovic Courtès <ludo@gnu.org> wrote:
Toggle quote (2 lines)> Oh I’m sorry, I think I misunderstood your question back then!
My poor English does not help either. :-)
Toggle quote (15 lines)>>> With this patch set, someone pulling guix-bimsb would just end up>>> pulling guix-past unauthenticated; there’s not even a warning.>>>>>> (There’s currently a warning in (guix channels), but only when pulling>>> an unauthenticated 'guix channel. It’s perhaps too early to have that>>> warning enabled for all channels. WDYT?)>>>> Enable the warning appears to me a good idea because this dependency is>> like "doing something I am not necessary aware in my back".>> I’m talking about the warning that says “this channel is> unauthenticated”, which is mostly orthogonal to the discussion at hand.> The reason I said it’s perhaps too early to enable it is that people> haven’t had a chance to make their channel “authenticable” yet.
Well, the possible scenarii are: when pulling guix-bimsb which ends upto pull guix-past:
1- unauthenticated guix-bimsb and unauthenticated guix-past 2- authenticated guix-bimsb and unauthenticated guix-past 3- unauthenticated guix-bimsb and authenticated guix-past 4- authenticated guix-bimsb and authenticated guix-past
The #1 and #4 do not deserve a warning.The point #3 neither and even the authentication of guix-past should beturned off, at least now.
The point #2 requires a warning. Because if I am pulling aauthenticated channel, I expect that all the code it pulls isauthenticated which will not be the case, so IMHO it deserves awarning.
Then it is up to the guix-bimsb channel to add an introduction for thedependency using the format you described.
Cheers,simon
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zimoun wrote on 1 Jul 15:09 +0200
Re: [bug#42048] [PATCH 0/6] Authenticated channels for everyone!
(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 42048@debbugs.gnu.org)
86a70j9ybi.fsf@gmail.com
On Wed, 01 Jul 2020 at 14:17, Ludovic Courtès <ludo@gnu.org> wrote:
Toggle quote (5 lines)> But of course, the new ‘introduction’ field of <channel> won’t be> recognized by older Guix versions. In that case, you should use the> output of ‘guix describe -f channels-sans-intro’ as I wrote in the> manual.
Older Guix versions means the Scheme lib and not Inferiors, right?
I mean, if I run using a Guix post-'introduction' "guix describe -fchannels", then I can run with another Guix post-'introduction' "guixtime-machine -C channels.scm", everything is fine.
However, I cannot use this post-'introduction' channels.scm file with apre-'introduction' Guix and "guix time-machine -C channels.scm" fails,right?

Toggle quote (17 lines)> In general, when a developer loses control over their key, another> committer should remove it right away form ‘.guix-authorizations’. (I> did that today following Brett’s message, for example.)>> Signatures on past commits can still be verified and everything is fine.> The (guix openpgp) code ignores key expiration and revocation; it “just”> verifies signatures.>>> Today, everything is fine, I sign and I do in introduction. Couple of>> months (or even years) later, my key will be compromised and so I will>> revoke it. What happens if I do "guix time-machine -C"?>> That’s OK. The keyring is distributed along with the channel still> contains your key, with or without a revocation certificate, but that> doesn’t prevent us from verifying signatures on past commits. (This is> different from what gpg does.)
It answers to my question about time-machine. Thank you.Now I have another one. :-)
Well, if now Eve has the control of an authorized key (for example theBrett's one) then you cannot distinguish between past valid signaturesto current malicious ones, even if the key is revoked, right?
(It is not a practical issue but it is a possible scenario.)
Cheers,simon
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Ludovic Courtès wrote on 1 Jul 17:54 +0200
(name . zimoun)(address . zimon.toutoune@gmail.com)(address . 42048@debbugs.gnu.org)
874kqrz0wv.fsf@gnu.org
zimoun <zimon.toutoune@gmail.com> skribis:
Toggle quote (17 lines)> On Wed, 01 Jul 2020 at 14:17, Ludovic Courtès <ludo@gnu.org> wrote:>>> But of course, the new ‘introduction’ field of <channel> won’t be>> recognized by older Guix versions. In that case, you should use the>> output of ‘guix describe -f channels-sans-intro’ as I wrote in the>> manual.>> Older Guix versions means the Scheme lib and not Inferiors, right?>> I mean, if I run using a Guix post-'introduction' "guix describe -f> channels", then I can run with another Guix post-'introduction' "guix> time-machine -C channels.scm", everything is fine.>> However, I cannot use this post-'introduction' channels.scm file with a> pre-'introduction' Guix and "guix time-machine -C channels.scm" fails,> right?
Yup!
Toggle quote (4 lines)> Well, if now Eve has the control of an authorized key (for example the> Brett's one) then you cannot distinguish between past valid signatures> to current malicious ones, even if the key is revoked, right?
Revocation in the OpenPGP sense doesn’t not matter at all. What mattersis whether the key is in ‘.guix-authorizations’. If we remove if fromthere in commit X, then any commit descending from X that is signed bythat key will be rejected. Past commits (ancestors of X) signed by thatkey are still considered authentic.
Ludo’.
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Ludovic Courtès wrote on 1 Jul 19:05 +0200
Re: [bug#42048] [PATCH 6/6] services: provenance: Save channel introductions.
(name . zimoun)(address . zimon.toutoune@gmail.com)
87wo3nxj1u.fsf@gnu.org
zimoun <zimon.toutoune@gmail.com> skribis:
Toggle quote (2 lines)> On Wed, 01 Jul 2020 at 14:12, Ludovic Courtès <ludo@gnu.org> wrote:
[...]
Toggle quote (5 lines)>> I’m talking about the warning that says “this channel is>> unauthenticated”, which is mostly orthogonal to the discussion at hand.>> The reason I said it’s perhaps too early to enable it is that people>> haven’t had a chance to make their channel “authenticable” yet.
Toggle quote (20 lines)> Well, the possible scenarii are: when pulling guix-bimsb which ends up> to pull guix-past:>> 1- unauthenticated guix-bimsb and unauthenticated guix-past> 2- authenticated guix-bimsb and unauthenticated guix-past> 3- unauthenticated guix-bimsb and authenticated guix-past> 4- authenticated guix-bimsb and authenticated guix-past>> The #1 and #4 do not deserve a warning.> The point #3 neither and even the authentication of guix-past should be> turned off, at least now.>> The point #2 requires a warning. Because if I am pulling a> authenticated channel, I expect that all the code it pulls is> authenticated which will not be the case, so IMHO it deserves a> warning.>> Then it is up to the guix-bimsb channel to add an introduction for the> dependency using the format you described.
Exactly. I agree that #2 is problematic, but if the authors ofguix-bimsb are aware that guix-past can also be authenticated, then Ithink it’s their responsibility to update their ‘.guix-channel’dependencies accordingly.
Ludo’.
L
L
Ludovic Courtès wrote on 1 Jul 23:50 +0200
(name . Ricardo Wurmus)(address . rekado@elephly.net)(address . 42048-done@debbugs.gnu.org)
87imf6ykf6.fsf@gnu.org
Hi,
Ricardo Wurmus <rekado@elephly.net> skribis:
Toggle quote (32 lines)> Ludovic Courtès <ludo@gnu.org> writes:>>> So yes, I suppose we would need to extend the ‘.guix-channel’ format for>> dependencies. Luckily it should be quite simply because that format is>> extensible; older Guix versions would ignore the ‘introduction’ field.>> It would look something like this:>>>> (channel>> (version 0)>> (dependencies>> (channel>> (name some-collection)>> (url "https://example.org/first-collection.git")>> (introduction (channel-introduction>> (version 0)>> (commit "…")>> (signer "…"))))>> (channel>> (name some-other-collection)>> (url "https://example.org/second-collection.git")>> (branch "testing")))) ;not an authenticated channel>>>> It does mean that a channel can indirectly trick you into turning off>> authentication for a dependent channel. But I think that’s within the>> expectations for channels: when you choose a channel, you trust it>> enough to run its code.>>>> WDYT?>> This sounds reasonable. I agree that you’ve got to trust the channel> authors anyway, so allowing them to provide the introduction is fair.
I went ahead and did that:
https://git.savannah.gnu.org/cgit/guix.git/commit/?id=d774c7b1218a3cc20079b19812da119f9ed26b54
Let me know what you think!
The whole series is now pushed:
d774c7b121 channels: Dependencies listed in '.guix-channel' can have an introduction. 884df77640 channels: Properly diagnose test failure. eb5cf39e66 services: provenance: Save channel introductions. 6d39f0cb77 guix describe: Display channel introductions and add 'channels-sans-intro'. 471550c28c channels: Save and interpret 'introduction' field in provenance data. 22a9699257 channels: Remove 'signature' from <channel-introduction>. 8b7d982e6a channels: Make channel introductions public. 6577682a6c channels: Add 'openpgp-fingerprint->bytevector'.
Thanks for your feedback,Ludo’.
Closed
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