summaryrefslogtreecommitdiff
path: root/eclass/verify-sig.eclass
blob: b74ed78290aaa433015d505eab624e922d37dd7e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
# Copyright 2020-2024 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2

# @ECLASS: verify-sig.eclass
# @MAINTAINER:
# Michał Górny <mgorny@gentoo.org>
# @SUPPORTED_EAPIS: 7 8
# @BLURB: Eclass to verify upstream signatures on distfiles
# @DESCRIPTION:
# verify-sig eclass provides a streamlined approach to verifying
# upstream signatures on distfiles.  Its primary purpose is to permit
# developers to easily verify signatures while bumping packages.
# The eclass removes the risk of developer forgetting to perform
# the verification, or performing it incorrectly, e.g. due to additional
# keys in the local keyring.  It also permits users to verify
# the developer's work.
#
# To use the eclass, start by packaging the upstream's key
# as sec-keys/openpgp-keys-*.  Then inherit the eclass, add detached
# signatures to SRC_URI and set VERIFY_SIG_OPENPGP_KEY_PATH.  The eclass
# provides verify-sig USE flag to toggle the verification.
#
# If you need to use signify, you may want to copy distfiles into WORKDIR to
# work around "Too many levels of symbolic links" error.
#
# A more complete guide can be found at:
# https://mgorny.pl/articles/verify-sig-by-example.html
#
# @EXAMPLE:
# Example use:
#
# @CODE
# inherit verify-sig
#
# SRC_URI="https://example.org/${P}.tar.gz
#   verify-sig? ( https://example.org/${P}.tar.gz.sig )"
# BDEPEND="
#   verify-sig? ( sec-keys/openpgp-keys-example )"
#
# VERIFY_SIG_OPENPGP_KEY_PATH=/usr/share/openpgp-keys/example.asc
# @CODE

case ${EAPI} in
	7|8) ;;
	*) die "${ECLASS}: EAPI ${EAPI:-0} not supported" ;;
esac

if [[ -z ${_VERIFY_SIG_ECLASS} ]]; then
_VERIFY_SIG_ECLASS=1

IUSE="verify-sig"

# @ECLASS_VARIABLE: VERIFY_SIG_METHOD
# @PRE_INHERIT
# @DESCRIPTION:
# Signature verification method to use.  The allowed value are:
#
#  - minisig -- verify signatures with (base64) Ed25519 public key using app-crypt/minisign
#  - openpgp -- verify PGP signatures using app-crypt/gnupg (the default)
#  - signify -- verify signatures with Ed25519 public key using app-crypt/signify
: "${VERIFY_SIG_METHOD:=openpgp}"

case ${VERIFY_SIG_METHOD} in
	minisig)
		BDEPEND="verify-sig? ( app-crypt/minisign )"
		;;
	openpgp)
		BDEPEND="
			verify-sig? (
				app-crypt/gnupg
				>=app-portage/gemato-20
			)
		"
		;;
	signify)
		BDEPEND="verify-sig? ( app-crypt/signify )"
		;;
	*)
		die "${ECLASS}: unknown method '${VERIFY_SIG_METHOD}'"
		;;
esac

# @ECLASS_VARIABLE: VERIFY_SIG_OPENPGP_KEY_PATH
# @DEFAULT_UNSET
# @DESCRIPTION:
# Path to key bundle used to perform the verification.  This is required
# when using default src_unpack.  Alternatively, the key path can be
# passed directly to the verification functions.
#
# The value of BROOT will be prepended to this path automatically.
#
# NB: this variable is also used for non-OpenPGP signatures.  The name
# contains "OPENPGP" for historical reasons.

# @ECLASS_VARIABLE: VERIFY_SIG_OPENPGP_KEYSERVER
# @DEFAULT_UNSET
# @DESCRIPTION:
# Keyserver used to refresh keys.  If not specified, the keyserver
# preference from the key will be respected.  If no preference
# is specified by the key, the GnuPG default will be used.
#
# Supported for OpenPGP only.

# @ECLASS_VARIABLE: VERIFY_SIG_OPENPGP_KEY_REFRESH
# @USER_VARIABLE
# @DESCRIPTION:
# Attempt to refresh keys via WKD/keyserver.  Set it to "yes"
# in make.conf to enable.  Note that this requires working Internet
# connection.
#
# Supported for OpenPGP only.
: "${VERIFY_SIG_OPENPGP_KEY_REFRESH:=no}"

# @FUNCTION: verify-sig_verify_detached
# @USAGE: <file> <sig-file> [<key-file>]
# @DESCRIPTION:
# Read the detached signature from <sig-file> and verify <file> against
# it.  <key-file> can either be passed directly, or it defaults
# to VERIFY_SIG_OPENPGP_KEY_PATH.  The function dies if verification
# fails.
verify-sig_verify_detached() {
	local file=${1}
	local sig=${2}
	local key=${3}

	if [[ -z ${key} ]]; then
		if [[ -z ${VERIFY_SIG_OPENPGP_KEY_PATH} ]]; then
			die "${FUNCNAME}: no key passed and VERIFY_SIG_OPENPGP_KEY_PATH unset"
		else
			key="${BROOT}${VERIFY_SIG_OPENPGP_KEY_PATH}"
		fi
	fi

	local extra_args=()
	[[ ${VERIFY_SIG_OPENPGP_KEY_REFRESH} == yes ]] || extra_args+=( -R )
	if [[ -n ${VERIFY_SIG_OPENPGP_KEYSERVER+1} ]]; then
		[[ ${VERIFY_SIG_METHOD} == openpgp ]] ||
			die "${FUNCNAME}: VERIFY_SIG_OPENPGP_KEYSERVER is not supported"

		extra_args+=(
			--keyserver "${VERIFY_SIG_OPENPGP_KEYSERVER}"
		)
	fi

	# GPG upstream knows better than to follow the spec, so we can't
	# override this directory.  However, there is a clean fallback
	# to GNUPGHOME.
	addpredict /run/user

	local filename=${file##*/}
	[[ ${file} == - ]] && filename='(stdin)'
	einfo "Verifying ${filename} ..."
	case ${VERIFY_SIG_METHOD} in
		minisig)
			minisign -V -P "$(<"${key}")" -x "${sig}" -m "${file}" ||
				die "minisig signature verification failed"
			;;
		openpgp)
			# gpg can't handle very long TMPDIR
			# https://bugs.gentoo.org/854492
			local -x TMPDIR=/tmp
			gemato openpgp-verify-detached -K "${key}" \
				"${extra_args[@]}" --no-require-all-good \
				"${sig}" "${file}" ||
				die "PGP signature verification failed"
			;;
		signify)
			signify -V -p "${key}" -m "${file}" -x "${sig}" ||
				die "Signify signature verification failed"
			;;
	esac
}

# @FUNCTION: verify-sig_verify_message
# @USAGE: <file> <output-file> [<key-file>]
# @DESCRIPTION:
# Verify that the file ('-' for stdin) contains a valid, signed PGP
# message and write the message into <output-file> ('-' for stdout).
# <key-file> can either be passed directly, or it defaults
# to VERIFY_SIG_OPENPGP_KEY_PATH.  The function dies if verification
# fails.  Note that using output from <output-file> is important as it
# prevents the injection of unsigned data.
verify-sig_verify_message() {
	local file=${1}
	local output_file=${2}
	local key=${3}

	if [[ -z ${key} ]]; then
		if [[ -z ${VERIFY_SIG_OPENPGP_KEY_PATH} ]]; then
			die "${FUNCNAME}: no key passed and VERIFY_SIG_OPENPGP_KEY_PATH unset"
		else
			key="${BROOT}${VERIFY_SIG_OPENPGP_KEY_PATH}"
		fi
	fi

	local extra_args=()
	[[ ${VERIFY_SIG_OPENPGP_KEY_REFRESH} == yes ]] || extra_args+=( -R )
	if [[ -n ${VERIFY_SIG_OPENPGP_KEYSERVER+1} ]]; then
		[[ ${VERIFY_SIG_METHOD} == openpgp ]] ||
			die "${FUNCNAME}: VERIFY_SIG_OPENPGP_KEYSERVER is not supported"

		extra_args+=(
			--keyserver "${VERIFY_SIG_OPENPGP_KEYSERVER}"
		)
	fi

	# GPG upstream knows better than to follow the spec, so we can't
	# override this directory.  However, there is a clean fallback
	# to GNUPGHOME.
	addpredict /run/user

	local filename=${file##*/}
	[[ ${file} == - ]] && filename='(stdin)'
	einfo "Verifying ${filename} ..."
	case ${VERIFY_SIG_METHOD} in
		minisig)
			minisign -V -P "$(<"${key}")" -x "${sig}" -o "${output_file}" -m "${file}" ||
				die "minisig signature verification failed"
			;;
		openpgp)
			# gpg can't handle very long TMPDIR
			# https://bugs.gentoo.org/854492
			local -x TMPDIR=/tmp
			gemato gpg-wrap -K "${key}" "${extra_args[@]}" -- \
				gpg --verify --output="${output_file}" "${file}" ||
				die "PGP signature verification failed"
			;;
		signify)
			signify -V -e -p "${key}" -m "${output_file}" -x "${file}" ||
				die "Signify signature verification failed"
			;;
	esac
}

# @FUNCTION: verify-sig_verify_unsigned_checksums
# @USAGE: <checksum-file> <format> <files>
# @DESCRIPTION:
# Verify the checksums for all files listed in the space-separated list
# <files> (akin to ${A}) using a <checksum-file>.  <format> specifies
# the checksum file format.  <checksum-file> can be "-" for stdin.
#
# The following formats are supported:
#  - sha256 -- sha256sum (<hash> <filename>)
#  - openssl-dgst -- openssl dgst (<algo>(<filename>)=<hash>)
#
# The function dies if one of the files does not match checksums or
# is missing from the checksum file.
#
# Note that this function itself can only verify integrity of the files.
# In order to verify their authenticity, the <checksum-file> must
# be verified against a signature first, e.g. using
# verify-sig_verify_detached.  If it contains inline signature, use
# verify-sig_verify_signed_checksums instead.
verify-sig_verify_unsigned_checksums() {
	local checksum_file=${1}
	local format=${2}
	local files=()
	read -r -d '' -a files <<<"${3}"
	local chksum_prog chksum_len algo=${format}

	case ${format} in
		sha256)
			chksum_len=64
			;;
		openssl-dgst)
			;;
		*)
			die "${FUNCNAME}: unknown checksum format ${format}"
			;;
	esac

	[[ ${checksum_file} == - ]] && checksum_file=/dev/stdin
	local line checksum filename junk ret=0 count=0
	local -A verified
	while read -r line; do
		if [[ ${line} == "-----BEGIN"* ]]; then
			die "${FUNCNAME}: PGP armor found, use verify-sig_verify_signed_checksums instead"
		fi

		case ${format} in
			sha256)
				read -r checksum filename junk <<<"${line}"
				[[ ${#checksum} -ne ${chksum_len} ]] && continue
				[[ -n ${checksum//[0-9a-f]} ]] && continue
				[[ -n ${junk} ]] && continue
				;;
			openssl-dgst)
				[[ ${line} != *"("*")="* ]] && continue
				checksum=${line##*)=}
				algo=${line%%(*}
				filename=${line#*(}
				filename=${filename%)=*}
				;;
		esac

		if ! has "${filename}" "${files[@]}"; then
			continue
		fi

		if "${algo,,}sum" -c --strict - <<<"${checksum} ${filename}"; then
			verified["${filename}"]=1
		else
			ret=1
		fi
	done < "${checksum_file}"

	[[ ${ret} -eq 0 ]] ||
		die "${FUNCNAME}: at least one file did not verify successfully"
	[[ ${#verified[@]} -eq ${#files[@]} ]] ||
		die "${FUNCNAME}: checksums for some of the specified files were missing"
}

# @FUNCTION: _gpg_verify_signed_checksums
# @INTERNAL
# @USAGE: <checksum-file> <algo> <files> [<key-file>]
# @DESCRIPTION:
# GnuPG-specific function to verify a signed checksums list.
_gpg_verify_signed_checksums() {
	local checksum_file=${1}
	local algo=${2}
	local files=${3}
	local key=${4}

	verify-sig_verify_unsigned_checksums - "${algo}" "${files}" < <(
		verify-sig_verify_message "${checksum_file}" - "${key}"
	)
}

# @FUNCTION: verify-sig_verify_signed_checksums
# @USAGE: <checksum-file> <algo> <files> [<key-file>]
# @DESCRIPTION:
# Verify the checksums for all files listed in the space-separated list
# <files> (akin to ${A}) using a signed <checksum-file>.  <algo> specifies
# the checksum algorithm (e.g. sha256).  <key-file> can either be passed
# directly, or it defaults to VERIFY_SIG_OPENPGP_KEY_PATH.
#
# The function dies if signature verification fails, the checksum file
# contains unsigned data, one of the files do not match checksums or
# are missing from the checksum file.
verify-sig_verify_signed_checksums() {
	local checksum_file=${1}
	local algo=${2}
	local files=()
	read -r -d '' -a files <<<"${3}"
	local key=${4}

	if [[ -z ${key} ]]; then
		if [[ -z ${VERIFY_SIG_OPENPGP_KEY_PATH} ]]; then
			die "${FUNCNAME}: no key passed and VERIFY_SIG_OPENPGP_KEY_PATH unset"
		else
			key="${BROOT}${VERIFY_SIG_OPENPGP_KEY_PATH}"
		fi
	fi

	case ${VERIFY_SIG_METHOD} in
		openpgp)
			_gpg_verify_signed_checksums \
				"${checksum_file}" "${algo}" "${files[@]}" "${key}"
			;;
		signify)
			signify -C -p "${key}" \
				-x "${checksum_file}" "${files[@]}" ||
				die "Signify signature verification failed"
			;;
	esac
}

# @FUNCTION: verify-sig_src_unpack
# @DESCRIPTION:
# Default src_unpack override that verifies signatures for all
# distfiles if 'verify-sig' flag is enabled.  The function dies if any
# of the signatures fails to verify or if any distfiles are not signed.
# Please write src_unpack() yourself if you need to perform partial
# verification.
verify-sig_src_unpack() {
	if use verify-sig; then
		local f suffix found
		local distfiles=() signatures=() nosigfound=() straysigs=()

		# find all distfiles and signatures, and combine them
		for f in ${A}; do
			found=
			for suffix in .asc .sig .minisig; do
				if [[ ${f} == *${suffix} ]]; then
					signatures+=( "${f}" )
					found=sig
					break
				else
					if has "${f}${suffix}" ${A}; then
						distfiles+=( "${f}" )
						found=dist+sig
						break
					fi
				fi
			done
			if [[ ! ${found} ]]; then
				nosigfound+=( "${f}" )
			fi
		done

		# check if all distfiles are signed
		if [[ ${#nosigfound[@]} -gt 0 ]]; then
			eerror "The following distfiles lack detached signatures:"
			for f in "${nosigfound[@]}"; do
				eerror "  ${f}"
			done
			die "Unsigned distfiles found"
		fi

		# check if there are no stray signatures
		for f in "${signatures[@]}"; do
			if ! has "${f%.*}" "${distfiles[@]}"; then
				straysigs+=( "${f}" )
			fi
		done
		if [[ ${#straysigs[@]} -gt 0 ]]; then
			eerror "The following signatures do not match any distfiles:"
			for f in "${straysigs[@]}"; do
				eerror "  ${f}"
			done
			die "Unused signatures found"
		fi

		# now perform the verification
		for f in "${signatures[@]}"; do
			verify-sig_verify_detached \
				"${DISTDIR}/${f%.*}" "${DISTDIR}/${f}"
		done
	fi

	# finally, unpack the distfiles
	default_src_unpack
}

fi

EXPORT_FUNCTIONS src_unpack