Merge bitcoin#7713: Fixes for verify-commits script

1e9aab0 Remove sipa's old revoked key from verify-commits (Peter Todd)
966151e Add README for verify-commits (Peter Todd)
11164ec Remove keys that are no longer used for merging (Peter Todd)
22421fa Remove pointless warning (Peter Todd)
9523e8a Make verify-commits path-independent (Matt Corallo)
f7d4a25 Make verify-commits POSIX-compliant (Matt Corallo)

Author: laanwj

contrib/verify-commits/README.md

@@ -0,0 +1,26 @@
+Tooling for verification of PGP signed commits
+----------------------------------------------
+
+This is an incomplete work in progress, but currently includes a pre-push hook
+script (`pre-push-hook.sh`) for maintainers to ensure that their own commits
+are PGP signed (nearly always merge commits), as well as a script to verify
+commits against a trusted keys list.
+
+
+Using verify-commits.sh safely
+------------------------------
+
+Remember that you can't use an untrusted script to verify itself. This means
+that checking out code, then running `verify-commits.sh` against `HEAD` is
+_not_ safe, because the version of `verify-commits.sh` that you just ran could
+be backdoored. Instead, you need to use a trusted version of verify-commits
+prior to checkout to make sure you're checking out only code signed by trusted
+keys:
+
+    git fetch origin && \
+      ./contrib/verify-commits/verify-commits.sh origin/master && \
+      git checkout origin/master
+
+Note that the above isn't a good UI/UX yet, and needs significant improvements
+to make it more convenient and reduce the chance of errors; pull-reqs
+improving this process would be much appreciated.

contrib/verify-commits/allow-revsig-commits

@@ -1,2 +0,0 @@
-586a29253dabec3ca0f1ccba9091daabd16b8411
-eddaba7b5692288087a926da5733e86b47274e4e

contrib/verify-commits/gpg.sh

@@ -1,8 +1,9 @@
 #!/bin/sh
-INPUT=$(</dev/stdin)
+INPUT=$(cat /dev/stdin)
 VALID=false
 REVSIG=false
-IFS=$'\n'
+IFS='
+'
 for LINE in $(echo "$INPUT" | gpg --trust-model always "$@" 2>/dev/null); do
 	case "$LINE" in
 	"[GNUPG:] VALIDSIG "*)
@@ -13,10 +14,9 @@ for LINE in $(echo "$INPUT" | gpg --trust-model always "$@" 2>/dev/null); do
 	"[GNUPG:] REVKEYSIG "*)
 		[ "$BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG" != 1 ] && exit 1
 		while read KEY; do
-			case "$LINE" in "[GNUPG:] REVKEYSIG ${KEY:24:40} "*)
+			case "$LINE" in "[GNUPG:] REVKEYSIG ${KEY#????????????????????????} "*)
 				REVSIG=true
-				GOODREVSIG="[GNUPG:] GOODSIG ${KEY:24:40} "
-				;;
+				GOODREVSIG="[GNUPG:] GOODSIG ${KEY#????????????????????????} "
 			esac
 		done < ./contrib/verify-commits/trusted-keys
 		;;

contrib/verify-commits/trusted-git-root

@@ -1 +1 @@
-165e323d851cc87213c7673c6f278e87a6f2e752
+82bcf405f6db1d55b684a1f63a4aabad376cdad7

contrib/verify-commits/trusted-keys

@@ -1,7 +1,3 @@
 71A3B16735405025D447E8F274810B012346C9A6
-1F4410F6A89268CE3197A84C57896D2FF8F0B657
-01CDF4627A3B88AAE4A571C87588242FBE38D3A8
-AF8BE07C7049F3A26B239D5325B3083201782B2F
-81291FA67D2C379A006A053FEAB5AF94D9E9ABE7
 3F1888C6DCA92A6499C4911FDBA1A67379A1A931
 32EE5C4C3FA15CCADB46ABE529D4BCB6416F53EC

contrib/verify-commits/verify-commits.sh

@@ -1,33 +1,28 @@
 #!/bin/sh
+# Not technically POSIX-compliant due to use of "local", but almost every
+# shell anyone uses today supports it, so its probably fine
 
 DIR=$(dirname "$0")
-
-echo "Please verify all commits in the following list are not evil:"
-git log "$DIR"
+[ "/${DIR#/}" != "$DIR" ] && DIR=$(dirname "$(pwd)/$0")
 
 VERIFIED_ROOT=$(cat "${DIR}/trusted-git-root")
-
-IS_REVSIG_ALLOWED () {
-	while read LINE; do
-		[ "$LINE" = "$1" ] && return 0
-	done < "${DIR}/allow-revsig-commits"
-	return 1
-}
+REVSIG_ALLOWED=$(cat "${DIR}/allow-revsig-commits")
 
 HAVE_FAILED=false
 IS_SIGNED () {
 	if [ $1 = $VERIFIED_ROOT ]; then
 		return 0;
 	fi
-	if IS_REVSIG_ALLOWED "$1"; then
+	if [ "${REVSIG_ALLOWED#*$1}" != "$REVSIG_ALLOWED" ]; then
 		export BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG=1
 	else
 		export BITCOIN_VERIFY_COMMITS_ALLOW_REVSIG=0
 	fi
 	if ! git -c "gpg.program=${DIR}/gpg.sh" verify-commit $1 > /dev/null 2>&1; then
 		return 1;
 	fi
-	local PARENTS=$(git show -s --format=format:%P $1)
+	local PARENTS
+	PARENTS=$(git show -s --format=format:%P $1)
 	for PARENT in $PARENTS; do
 		if IS_SIGNED $PARENT > /dev/null; then
 			return 0;