Eli Schwartz <eschwartz@gentoo.org> writes:

The current state of verify-sig support is a bit awkward. We rely on validating distfiles against a known trusted keyring, but creating the
known trusted keyring is basically all manual verification. We somehow
decide an ascii armored key is good enough without any portage
assistance, then arrange to download it and trust it by Manifest hash.
How do we know when updating a key is actually safe?

This eclass handles the problem in a manner inspired in part by pacman.
We require an eclass variable that lists all permitted PGP fingerprints,
and the eclass is responsible checking that list against the keys we
will install. It comes with a mechanism for computing SRC_URI for a
couple of well known locations, or you can append your own in the
ebuild.

Key rotations, both expected and malicious, are easily detected by
checking the git log for changes to declared fingerprints in a bump. The former can be rationalized in the commit message. So can the latter, but
in most cases those will be rejected during peer review.

LGTM. Thanks.

Signed-off-by: Eli Schwartz <eschwartz@gentoo.org>
---
eclass/sec-keys.eclass | 202 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 202 insertions(+)
create mode 100644 eclass/sec-keys.eclass

diff --git a/eclass/sec-keys.eclass b/eclass/sec-keys.eclass
new file mode 100644
index 000000000000..1db752de30a1
--- /dev/null
+++ b/eclass/sec-keys.eclass
@@ -0,0 +1,202 @@
+# Copyright 2024-2025 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# @ECLASS: sec-keys.eclass
+# @MAINTAINER:
+# Eli Schwartz <eschwartz@gentoo.org>
+# @AUTHOR:
+# Eli Schwartz <eschwartz@gentoo.org>
+# @SUPPORTED_EAPIS: 8
+# @BLURB: Provides a uniform way of handling ebuilds which package PGP key material
+# @DESCRIPTION:
+# This eclass provides a streamlined approach to finding suitable source
+# material for OpenPGP keys used by the verify-sig eclass. Its primary
+# purpose is to permit developers to easily and securely package new
+# sec-keys/* packages. The eclass removes the risk of developers
+# accidentally packaging malformed key material, or neglecting to
+# notice when PGP identities have changed.
+#
+# To use the eclass, define SEC_KEYS_VALIDPGPKEYS to contain the
+# fingerprint of the key and the short name of the key's owner.
+#
+# @EXAMPLE:
+# Example use:
+#
+# @CODE
+# SEC_KEYS_VALIDPGPKEYS=(
+# '3DB7F3CA6C1D90B99FE25B38D4B476A4D175C54F:bjones:ubuntu'
+# '4EC8A4DB7D2E01C00AF36C49E5C587B5E286C65A:jsmith:github,openpgp'
+# # key only available on personal website, use manual SRC_URI
+# '5FD9B5EC8E3F12D11BA47D50F6D698C6F397D76B:awhite:manual'
+# )
+#
+# inherit sec-keys
+#
+# SRC_URI+="https://awhite.com/awhite.gpg -> awhite-${PV}.gpg"
+# @CODE
+
+case ${EAPI} in
+ 8) ;;
+ *) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
+esac
+
+if [[ ! ${_SEC_KEYS_ECLASS} ]]; then
+_SEC_KEYS_ECLASS=1
+
+inherit edo
+
+# @ECLASS_VARIABLE: SEC_KEYS_VALIDPGPKEYS
+# @PRE_INHERIT
+# @DEFAULT_UNSET
+# @DESCRIPTION:
+# Mapping of fingerprints, name, and optional locations of PGP keys to
+# include, separated by colons. The allowed values for a location are:
+#
+# - gentoo -- fetch key by fingerprint from https://keys.gentoo.org
+#
+# - github -- fetch key from github.com/${name}.pgp
+#
+# - openpgp -- fetch key by fingerprint from https://keys.openpgp.org
+#
+# - ubuntu -- fetch key by fingerprint from http://keyserver.ubuntu.com
+#
+# - manual -- do not add to SRC_URI, the ebuild will provide a custom
+# download location
+_sec_keys_set_globals() {
+ local key fingerprint name loc locations=() remote
+
+ for key in "${SEC_KEYS_VALIDPGPKEYS[@]}"; do
+ fingerprint=${key%%:*}
+ name=${key#${fingerprint}:}; name=${name%%:*}
+ IFS=, read -r -a locations <<<"${key##*:}"
+ [[ ${locations[@]} ]] || die "${ECLASS}: ${name}: PGP key remote is mandatory"
+ for loc in "${locations[@]}"; do
+ case ${loc} in
+ gentoo) remote="https://keys.gentoo.org/pks/lookup?op=get&search=0x${fingerprint}";;
+ github) remote="https://github.com/${name}.gpg";;
+ openpgp) remote="https://keys.openpgp.org/vks/v1/by-fingerprint/${fingerprint}";;
+ ubuntu) remote="https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x${fingerprint}";;
+ # provided via manual SRC_URI
+ manual) continue;;
+ *) die "${ECLASS}: unknown PGP key remote: ${loc}";;
+ esac
+ SRC_URI+="
+ ${remote} -> openpgp-keys-${name}-${loc}-${PV}.asc
+ "
+ done
+ done
+}
+_sec_keys_set_globals
+unset -f _sec_keys_set_globals
+
+S=${WORKDIR}
+
+LICENSE="public-domain"
+SLOT="0"
+
+IUSE="test"
+PROPERTIES="test_network"
+RESTRICT="!test? ( test )"
+
+BDEPEND="
+ app-crypt/gnupg
+ test? ( app-crypt/pgpdump )
+"
+
+
+
+# @FUNCTION: sec-keys_src_compile
+# @DESCRIPTION:
+# Default src_compile override that:
+#
+# - imports all public keys into a keyring
+#
+# - validates that they are listed in SEC_KEYS_VALIDPGPKEYS
+#
+# - minifies and exports them back into a unified keyfile +sec-keys_src_compile() {
+ local -x GNUPGHOME=${WORKDIR}/gnupg
+ local fingerprint
+ local gpg_command=(gpg --export-options export-minimal)
+
+ mkdir -m700 -p "${GNUPGHOME}" || die
+ cat <<- EOF > "${GNUPGHOME}"/gpg.conf || die
+ no-secmem-warning
+ EOF
+
+ pushd "${DISTDIR}" >/dev/null || die
+ gpg --import ${A} || die
+ popd >/dev/null || die
+
+ local line imported_keys=() found=0
+ while IFS=: read -r -a line; do
+ if [[ ${line[0]} = pub ]]; then
+ # new key
+ found=0
+ elif [[ ${found} = 0 && ${line[0]} = fpr ]]; then
+ # primary fingerprint
+ imported_keys+=("${line[9]}")
+ found=1
+ fi
+ done < <(gpg --batch --list-keys --with-colons || die)
+
+ printf '%s\n' "${imported_keys[@]}" | sort > imported_keys.list || die + printf '%s\n' "${SEC_KEYS_VALIDPGPKEYS[@]%%:*}" | sort > allowed_keys.list || die
+
+ local extra_keys=($(comm -23 imported_keys.list allowed_keys.list || die))
+ local missing_keys=($(comm -13 imported_keys.list allowed_keys.list || die))
+
+ if [[ ${#extra_keys[@]} != 0 ]]; then
+ die "Too many keys found. Suspicious keys: ${extra_keys[@]}"
+ fi
+ if [[ ${#missing_keys[@]} != 0 ]]; then
+ die "Too few keys found. Unavailable keys: ${missing_keys[@]}" + fi
+
+ for fingerprint in "${SEC_KEYS_VALIDPGPKEYS[@]%%:*}"; do
+ local uids=()
+ mapfile -t uids < <("${gpg_command[@]}" --list-key --with-colons ${fingerprint} | awk -F: '/^uid/{print $10}' || die)
+ edo "${gpg_command[@]}" "${uids[@]/#/--comment=}" --export --armor "${fingerprint}" > "${fingerprint}.asc"
+ cat ${fingerprint}.asc >> ${PN#openpgp-keys-}.asc || die
+ done
+}
+
+sec-keys_src_test() {
+ local -x GNUPGHOME=${WORKDIR}/gnupg
+ local key fingerprint name server
+ local gpg_command=(gpg --export-options export-minimal)
+
+ # Best-effort attempt to check for updates. keyservers can and usually + # do fail for weird reasons, (such as being unable to import a key
+ # without a uid) as well as normal reasons, like the key being exclusive
+ # to a different keyserver. this isn't a reason to fail src_test.
+ for server in keys.gentoo.org keys.openpgp.org keyserver.ubuntu.com; do + gpg --refresh-keys --keyserver "hkps://${server}"
+ done
+ for key in "${SEC_KEYS_VALIDPGPKEYS[@]}"; do
+ if [[ ${key##*:} = *github* ]]; then
+ name=${key#*:}; name=${name%%:*}
+ wget -qO- https://github.com/${name}.gpg | gpg --import || die

I (still) think this should have a pipestatus, if nothing else to be a
good example and avoid possible lint issues down the road.

+ fi
+ done
+
+ for fingerprint in "${SEC_KEYS_VALIDPGPKEYS[@]%%:*}"; do
+ pgpdump "${fingerprint}.asc" > "${fingerprint}.pgpdump" || die + "${gpg_command[@]}" --export "${fingerprint}" | pgpdump

"${fingerprint}.pgpdump.new" || die

... and here.

+ diff -u "${fingerprint}.pgpdump" "${fingerprint}.pgpdump.new" || die "updates available for PGP key: ${fingerprint}"
+ done
+
+}
+
+# @FUNCTION: sec-keys_src_install
+# @DESCRIPTION:
+# Default src_install override that installs an ascii-armored keyfile
+# installed to the standard /usr/share/openpgp-keys.
+sec-keys_src_install() {
+ insinto /usr/share/openpgp-keys
+ doins ${PN#openpgp-keys-}.asc
+}
+
+fi
+
+EXPORT_FUNCTIONS src_compile src_test src_install

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On 7/28/25 11:31 AM, Sam James wrote:

+ for key in "${SEC_KEYS_VALIDPGPKEYS[@]}"; do
+ if [[ ${key##*:} = *github* ]]; then
+ name=${key#*:}; name=${name%%:*}
+ wget -qO- https://github.com/${name}.gpg | gpg --import || die

I (still) think this should have a pipestatus, if nothing else to be a
good example and avoid possible lint issues down the road.

Okay, I remember this private conversation now -- at the time, I refused
on the grounds it would entail using the name "assert". :P

Will add.

+ fi
+ done
+
+ for fingerprint in "${SEC_KEYS_VALIDPGPKEYS[@]%%:*}"; do
+ pgpdump "${fingerprint}.asc" > "${fingerprint}.pgpdump" || die >> + "${gpg_command[@]}" --export "${fingerprint}" | pgpdump

"${fingerprint}.pgpdump.new" || die

... and here.

(And for context, this is safe because pgpdump has a reliable exit code
even if given a half-formed key missing the closing boundary. Still, I
agree that for consistency and as a good example it's fine to do.)


--
Eli Schwartz

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