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[213.222.131.28]) by smtp.gmail.com with ESMTPSA id u4sm9396207ejc.19.2021.09.27.17.41.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Sep 2021 17:41:56 -0700 (PDT) From: Attila Lendvai Date: Tue, 28 Sep 2021 02:40:06 +0200 Message-Id: <20210928004005.28786-4-attila@lendvai.name> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210928004005.28786-1-attila@lendvai.name> References: <20210928004005.28786-1-attila@lendvai.name> MIME-Version: 1.0 X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: guix-patches@gnu.org List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-patches-bounces+patchwork=mira.cbaines.net@gnu.org Sender: "Guix-patches" X-getmail-retrieved-from-mailbox: Patches Also authenticate the channel intro commit. * guix/git-authenticate.scm (authenticate-commit): Reword and extend the error message to point to the relevant part of the manual. (authenticate-repository): Eliminate optimizations to make the code path less dependent on the input. Always trust the intro-commit itself. Always call verify-introductory-commit. (verify-introductory-commit): Check if the commit contains the key that was used to sign it, and issue a warning otherwise. This is to avoid the confusion caused by only the *second* commit yielding an error, because intro-commits are always trusted. (authenticate-commit): Clarify error message. (authorized-keys-at-commit): Factored out to the toplevel from commit-authorized-keys. --- guix/channels.scm | 4 +- guix/git-authenticate.scm | 153 ++++++++++++++++++++++---------------- 2 files changed, 91 insertions(+), 66 deletions(-) diff --git a/guix/channels.scm b/guix/channels.scm index e4e0428eb5..b84064537f 100644 --- a/guix/channels.scm +++ b/guix/channels.scm @@ -347,8 +347,8 @@ commits)...~%") (progress-reporter/bar (length commits))) (define authentic-commits - ;; Consider the currently-used commit of CHANNEL as authentic so - ;; authentication can skip it and all its closure. + ;; Optimization: consider the currently-used commit of CHANNEL as + ;; authentic, so that authentication can skip it and all its closure. (match (find (lambda (candidate) (eq? (channel-name candidate) (channel-name channel))) (current-channels)) diff --git a/guix/git-authenticate.scm b/guix/git-authenticate.scm index ab3fcd8b2f..713642d2ea 100644 --- a/guix/git-authenticate.scm +++ b/guix/git-authenticate.scm @@ -30,6 +30,7 @@ #:select (cache-directory with-atomic-file-output)) #:use-module ((guix build utils) #:select (mkdir-p)) + #:use-module (guix diagnostics) #:use-module (guix progress) #:use-module (srfi srfi-1) #:use-module (srfi srfi-11) @@ -38,6 +39,7 @@ #:use-module (srfi srfi-35) #:use-module (rnrs bytevectors) #:use-module (rnrs io ports) + #:use-module (ice-9 exceptions) #:use-module (ice-9 match) #:autoload (ice-9 pretty-print) (pretty-print) #:export (read-authorizations @@ -159,11 +161,10 @@ return a list of authorized fingerprints." (string-downcase (string-filter char-set:graphic fingerprint)))) fingerprints)))) -(define* (commit-authorized-keys repository commit - #:optional (default-authorizations '())) - "Return the list of OpenPGP fingerprints authorized to sign COMMIT, based on -authorizations listed in its parent commits. If one of the parent commits -does not specify anything, fall back to DEFAULT-AUTHORIZATIONS." +(define (authorized-keys-at-commit repository commit default-authorizations) + "Return the list of authorized key fingerprints from the '.guix-authorizations' +file at the given commit." + (define (parents-have-authorizations-file? commit) ;; Return true if at least one of the parents of COMMIT has the ;; '.guix-authorizations' file. @@ -185,28 +186,35 @@ does not specify anything, fall back to DEFAULT-AUTHORIZATIONS." to remove '.guix-authorizations' file") (oid->string (commit-id commit))))))) - (define (commit-authorizations commit) - (catch 'git-error - (lambda () - (let* ((tree (commit-tree commit)) - (entry (tree-entry-bypath tree ".guix-authorizations")) - (blob (blob-lookup repository (tree-entry-id entry)))) - (read-authorizations - (open-bytevector-input-port (blob-content blob))))) - (lambda (key error) - (if (= (git-error-code error) GIT_ENOTFOUND) - (begin - ;; Prevent removal of '.guix-authorizations' since it would make - ;; it trivial to force a fallback to DEFAULT-AUTHORIZATIONS. - (assert-parents-lack-authorizations commit) - default-authorizations) - (throw key error))))) + (catch 'git-error + (lambda () + (let* ((tree (commit-tree commit)) + (entry (tree-entry-bypath tree ".guix-authorizations")) + (blob (blob-lookup repository (tree-entry-id entry)))) + (read-authorizations + (open-bytevector-input-port (blob-content blob))))) + (lambda (key error) + (if (= (git-error-code error) GIT_ENOTFOUND) + (begin + ;; Prevent removal of '.guix-authorizations' since it would make + ;; it trivial to force a fallback to DEFAULT-AUTHORIZATIONS. + (assert-parents-lack-authorizations commit) + default-authorizations) + (throw key error))))) +(define* (commit-authorized-keys repository commit + #:optional (default-authorizations '())) + "Return the list of OpenPGP fingerprints authorized to sign COMMIT, based on +authorizations listed in its parent commits. If one of the parent commits +does not specify anything, fall back to DEFAULT-AUTHORIZATIONS." (match (commit-parents commit) (() default-authorizations) (parents (apply lset-intersection bytevector=? - (map commit-authorizations parents))))) + (map (lambda (commit) + (authorized-keys-at-commit repository commit + default-authorizations)) + parents))))) (define* (authenticate-commit repository commit keyring #:key (default-authorizations '())) @@ -236,8 +244,8 @@ not specify anything, fall back to DEFAULT-AUTHORIZATIONS." (condition (&unauthorized-commit-error (commit id) (signing-key signing-key))) - (formatted-message (G_ "commit ~a not signed by an authorized \ -key: ~a") + (formatted-message (G_ "commit ~a is signed by an unauthorized \ +key: ~a\nSee info guix \"Specifying Channel Authorizations\".") (oid->string id) (openpgp-format-fingerprint (openpgp-public-key-fingerprint @@ -356,7 +364,8 @@ authenticated (only COMMIT-ID is written to cache, though)." (base64-encode (sha256 (string->utf8 (repository-directory repository)))))) -(define (verify-introductory-commit repository keyring commit expected-signer) +(define (verify-introductory-commit repository commit expected-signer keyring + authorizations) "Look up COMMIT in REPOSITORY, and raise an exception if it is not signed by EXPECTED-SIGNER." (define actual-signer @@ -364,13 +373,25 @@ EXPECTED-SIGNER." (commit-signing-key repository (commit-id commit) keyring))) (unless (bytevector=? expected-signer actual-signer) - (raise (formatted-message (G_ "initial commit ~a is signed by '~a' \ + (raise (make-compound-condition + (condition (&unauthorized-commit-error (commit (commit-id commit)) + (signing-key actual-signer))) + (formatted-message (G_ "initial commit ~a is signed by '~a' \ instead of '~a'") - (oid->string (commit-id commit)) - (openpgp-format-fingerprint actual-signer) - (openpgp-format-fingerprint expected-signer))))) - -(define* (authenticate-repository repository start signer + (oid->string (commit-id commit)) + (openpgp-format-fingerprint actual-signer) + (openpgp-format-fingerprint expected-signer))))) + (unless (member actual-signer + (authorized-keys-at-commit repository commit authorizations) + bytevector=?) + ;; FIXME Is this the right way to tell the user about this situation? It + ;; would also be nice if the tests could assert for this warning. + (warning (G_ "initial commit ~a does not add \ +the key it is signed with (~a) to the '.guix-authorizations' file.") + (oid->string (commit-id commit)) + (openpgp-format-fingerprint actual-signer)))) + +(define* (authenticate-repository repository intro-commit-hash intro-signer #:key (keyring-reference "keyring") (cache-key (repository-cache-key repository)) @@ -380,11 +401,12 @@ instead of '~a'") (historical-authorizations '()) (make-reporter (const progress-reporter/silent))) - "Authenticate REPOSITORY up to commit END, an OID. Authentication starts -with commit START, an OID, which must be signed by SIGNER; an exception is -raised if that is not the case. Commits listed in AUTHENTIC-COMMITS and their -closure are considered authentic. Return an alist mapping OpenPGP public keys -to the number of commits signed by that key that have been traversed. + "Authenticate REPOSITORY up to commit END, an OID. Authentication starts with +commit INTRO-COMMIT-HASH, an OID, which must be signed by INTRO-SIGNER; an +exception is raised if that is not the case. Commits listed in +AUTHENTIC-COMMITS and their closure are considered authentic. Return an +alist mapping OpenPGP public keys to the number of commits signed by that +key that have been traversed. The OpenPGP keyring is loaded from KEYRING-REFERENCE in REPOSITORY, where KEYRING-REFERENCE is the name of a branch. The list of authenticated commits @@ -393,8 +415,10 @@ is cached in the authentication cache under CACHE-KEY. HISTORICAL-AUTHORIZATIONS must be a list of OpenPGP fingerprints (bytevectors) denoting the authorized keys for commits whose parent lack the '.guix-authorizations' file." - (define start-commit - (commit-lookup repository start)) + + (define intro-commit + (commit-lookup repository intro-commit-hash)) + (define end-commit (commit-lookup repository end)) @@ -404,36 +428,37 @@ denoting the authorized keys for commits whose parent lack the (define authenticated-commits ;; Previously-authenticated commits that don't need to be checked again. (filter-map (lambda (id) + ;; We need to tolerate when cached commits disappear due to + ;; --allow-downgrades. (false-if-git-not-found (commit-lookup repository (string->oid id)))) (append (previously-authenticated-commits cache-key) - authentic-commits))) + authentic-commits + ;; The intro commit is unconditionally trusted. + (list (oid->string intro-commit-hash))))) (define commits ;; Commits to authenticate, excluding the closure of ;; AUTHENTICATED-COMMITS. - (commit-difference end-commit start-commit - authenticated-commits)) - - ;; When COMMITS is empty, it's because END-COMMIT is in the closure of - ;; START-COMMIT and/or AUTHENTICATED-COMMITS, in which case it's known to - ;; be authentic already. - (if (null? commits) - '() - (let ((reporter (make-reporter start-commit end-commit commits))) - ;; If it's our first time, verify START-COMMIT's signature. - (when (null? authenticated-commits) - (verify-introductory-commit repository keyring - start-commit signer)) - - (let ((stats (call-with-progress-reporter reporter - (lambda (report) - (authenticate-commits repository commits - #:keyring keyring - #:default-authorizations - historical-authorizations - #:report-progress report))))) - (cache-authenticated-commit cache-key - (oid->string (commit-id end-commit))) - - stats)))) + (commit-difference end-commit intro-commit + authenticated-commits)) + + (verify-introductory-commit repository intro-commit + intro-signer keyring + historical-authorizations) + + (let* ((reporter (make-reporter intro-commit end-commit commits)) + (stats (call-with-progress-reporter reporter + (lambda (report) + (authenticate-commits repository commits + #:keyring keyring + #:default-authorizations + historical-authorizations + #:report-progress report))))) + ;; Note that this will make the then current end commit of any channel, + ;; that has been used/trusted in the past with a channel introduction, + ;; remain trusted until the cache is cleared. + (cache-authenticated-commit cache-key + (oid->string (commit-id end-commit))) + + stats))