From e78275608065ef073775fabb9f1a757da65851f2 Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Sun, 7 Jun 2020 23:06:41 +0200 Subject: git-authenticate: Prevent removal of '.guix-authorizations'. * guix/git-authenticate.scm (commit-authorized-keys) [parents-have-authorizations-file?, assert-parents-lack-authorizations]: New procedures. Use the latter before returning DEFAULT-AUTHORIZATIONS. * guix/git.scm (false-if-git-not-found): Export. * guix/tests/git.scm (populate-git-repository): Add 'remove' clause. * tests/git-authenticate.scm ("signed commits, .guix-authorizations removed"): New test. --- guix/git-authenticate.scm | 28 +++++++++++++++++++++++++++- guix/git.scm | 1 + guix/tests/git.scm | 3 +++ tests/git-authenticate.scm | 41 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 72 insertions(+), 1 deletion(-) diff --git a/guix/git-authenticate.scm b/guix/git-authenticate.scm index b73f957105..00d22ef479 100644 --- a/guix/git-authenticate.scm +++ b/guix/git-authenticate.scm @@ -19,6 +19,7 @@ (define-module (guix git-authenticate) #:use-module (git) #:use-module (guix base16) + #:use-module ((guix git) #:select (false-if-git-not-found)) #:use-module (guix i18n) #:use-module (guix openpgp) #:use-module ((guix utils) @@ -145,6 +146,27 @@ (define* (commit-authorized-keys repository commit "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 (parents-have-authorizations-file? commit) + ;; Return true if at least one of the parents of COMMIT has the + ;; '.guix-authorizations' file. + (find (lambda (commit) + (false-if-git-not-found + (tree-entry-bypath (commit-tree commit) + ".guix-authorizations"))) + (commit-parents commit))) + + (define (assert-parents-lack-authorizations commit) + ;; If COMMIT removes the '.guix-authorizations' file found in one of its + ;; parents, raise an error. + (when (parents-have-authorizations-file? commit) + (raise (condition + (&unauthorized-commit-error (commit (commit-id commit)) + (signing-key #f)) + (&message + (message (format #f (G_ "commit ~a attempts \ +to remove '.guix-authorizations' file") + (oid->string (commit-id commit))))))))) + (define (commit-authorizations commit) (catch 'git-error (lambda () @@ -155,7 +177,11 @@ (define (commit-authorizations commit) (open-bytevector-input-port (blob-content blob))))) (lambda (key error) (if (= (git-error-code error) GIT_ENOTFOUND) - default-authorizations + (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))))) (apply lset-intersection bytevector=? diff --git a/guix/git.scm b/guix/git.scm index 1c45afa050..1671f57d9f 100644 --- a/guix/git.scm +++ b/guix/git.scm @@ -39,6 +39,7 @@ (define-module (guix git) honor-system-x509-certificates! with-repository + false-if-git-not-found update-cached-checkout url+commit->name latest-repository-commit diff --git a/guix/tests/git.scm b/guix/tests/git.scm index 5d7056bb53..b8e5f7e643 100644 --- a/guix/tests/git.scm +++ b/guix/tests/git.scm @@ -76,6 +76,9 @@ (define (git command . args) port))) (git "add" file) (loop rest))) + ((('remove file) rest ...) + (git "rm" "-f" file) + (loop rest)) ((('commit text) rest ...) (git "commit" "-m" text) (loop rest)) diff --git a/tests/git-authenticate.scm b/tests/git-authenticate.scm index 5937c37ee6..84689d628e 100644 --- a/tests/git-authenticate.scm +++ b/tests/git-authenticate.scm @@ -282,5 +282,46 @@ (define (correct? c commit) merge master3) #:keyring-reference "master")))))) +(unless (gpg+git-available?) (test-skip 1)) +(test-assert "signed commits, .guix-authorizations removed" + (with-fresh-gnupg-setup (list %ed25519-public-key-file + %ed25519-secret-key-file) + (with-temporary-git-repository directory + `((add "signer.key" ,(call-with-input-file %ed25519-public-key-file + get-string-all)) + (add ".guix-authorizations" + ,(object->string + `(authorizations (version 0) + ((,(key-fingerprint + %ed25519-public-key-file) + (name "Charlie")))))) + (commit "zeroth commit") + (add "a.txt" "A") + (commit "first commit" + (signer ,(key-fingerprint %ed25519-public-key-file))) + (remove ".guix-authorizations") + (commit "second commit" + (signer ,(key-fingerprint %ed25519-public-key-file))) + (add "b.txt" "B") + (commit "third commit" + (signer ,(key-fingerprint %ed25519-public-key-file)))) + (with-repository directory repository + (let ((commit1 (find-commit repository "first")) + (commit2 (find-commit repository "second")) + (commit3 (find-commit repository "third"))) + ;; COMMIT1 and COMMIT2 are fine. + (and (authenticate-commits repository (list commit1 commit2) + #:keyring-reference "master") + + ;; COMMIT3 is rejected because COMMIT2 removes + ;; '.guix-authorizations'. + (guard (c ((unauthorized-commit-error? c) + (oid=? (git-authentication-error-commit c) + (commit-id commit2)))) + (authenticate-commits repository + (list commit1 commit2 commit3) + #:keyring-reference "master") + 'failed))))))) + (test-end "git-authenticate") -- cgit v1.2.3