runas_userlist_matches: fix matching a Runas_Spec with an empty runas user.

We should only match a rule with an empty runas user if a group was
specified on the command line (sudo -g) without a user (no -u option)
or the user specified their own name on the command line.
GitHub issue #290

MANIFEST

@@ -1098,6 +1098,8 @@ plugins/sudoers/regress/testsudoers/test26.out.ok
 plugins/sudoers/regress/testsudoers/test26.sh
 plugins/sudoers/regress/testsudoers/test27.out.ok
 plugins/sudoers/regress/testsudoers/test27.sh
+plugins/sudoers/regress/testsudoers/test28.out.ok
+plugins/sudoers/regress/testsudoers/test28.sh
 plugins/sudoers/regress/testsudoers/test3.out.ok
 plugins/sudoers/regress/testsudoers/test3.sh
 plugins/sudoers/regress/testsudoers/test4.out.ok

plugins/sudoers/match.c

@@ -188,8 +188,14 @@ runas_userlist_matches(const struct sudoers_parse_tree *parse_tree,
 		    user_matched = !m->negated;
 		break;
 	    case MYSELF:
-		if (!ISSET(sudo_user.flags, RUNAS_USER_SPECIFIED) ||
-		    strcmp(user_name, runas_pw->pw_name) == 0)
+		/*
+		 * Only match a rule with an empty runas user if a group
+		 * was specified on the command line without a user _or_
+		 * the user specified their own name on the command line.
+		 */
+		if ((!ISSET(sudo_user.flags, RUNAS_USER_SPECIFIED) &&
+			ISSET(sudo_user.flags, RUNAS_GROUP_SPECIFIED)) ||
+			strcmp(user_name, runas_pw->pw_name) == 0)
 		    user_matched = !m->negated;
 		break;
 	}

plugins/sudoers/regress/testsudoers/test28.out.ok

@@ -0,0 +1,117 @@
+This should match the 'ALL=ALL' rule.
+Parses OK
+
+Entries for user admin:
+
+ALL = (admin : staff) NOPASSWD: ALL
+	host  allowed
+	runas unmatched
+
+ALL = ALL
+	host  allowed
+	runas allowed
+	cmnd  allowed
+
+Command allowed
+
+This should match the 'ALL=ALL' rule.
+Parses OK
+
+Entries for user admin:
+
+ALL = ALL
+	host  allowed
+	runas allowed
+	cmnd  allowed
+
+Command allowed
+
+This should match the 'ALL=(:staff) NOPASSWD: ALL' rule.
+Parses OK
+
+Entries for user admin:
+
+ALL = (admin : staff) NOPASSWD: ALL
+	host  allowed
+	runas allowed
+	cmnd  allowed
+
+Command allowed
+
+This should match the 'ALL=(:staff) NOPASSWD: ALL' rule.
+Parses OK
+
+Entries for user admin:
+
+ALL = ALL
+	host  allowed
+	runas unmatched
+
+ALL = (admin : staff) NOPASSWD: ALL
+	host  allowed
+	runas allowed
+	cmnd  allowed
+
+Command allowed
+
+This should match the 'ALL=(:staff) NOPASSWD: ALL' rule.
+Parses OK
+
+Entries for user admin:
+
+ALL = ALL
+	host  allowed
+	runas unmatched
+
+ALL = (admin : staff) NOPASSWD: ALL
+	host  allowed
+	runas allowed
+	cmnd  allowed
+
+Command allowed
+
+This should match the 'ALL=(:staff) NOPASSWD: ALL' rule.
+Parses OK
+
+Entries for user admin:
+
+ALL = ALL
+	host  allowed
+	runas unmatched
+
+ALL = (admin : staff) NOPASSWD: ALL
+	host  allowed
+	runas allowed
+	cmnd  allowed
+
+Command allowed
+
+This should not match any rules.
+Parses OK
+
+Entries for user admin:
+
+ALL = ALL
+	host  allowed
+	runas unmatched
+
+ALL = (admin : staff) NOPASSWD: ALL
+	host  allowed
+	runas unmatched
+
+Command unmatched
+
+This should not match any rules.
+Parses OK
+
+Entries for user admin:
+
+ALL = ALL
+	host  allowed
+	runas unmatched
+
+ALL = (admin : users) NOPASSWD: ALL
+	host  allowed
+	runas unmatched
+
+Command unmatched

plugins/sudoers/regress/testsudoers/test28.sh

@@ -0,0 +1,99 @@
+#!/bin/sh
+#
+# Verify that a rule with an empty Runas user matches correctly.
+#
+
+: ${TESTSUDOERS=testsudoers}
+
+exec 2>&1
+
+status=0
+
+echo "This should match the 'ALL=ALL' rule."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group \
+    admin /bin/ls <<'EOF'
+admin ALL = ALL
+ALL ALL=(:staff) NOPASSWD: ALL
+EOF
+if [ $? -ne 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should match the 'ALL=ALL' rule."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group \
+    admin /bin/ls <<'EOF'
+ALL ALL=(:staff) NOPASSWD: ALL
+admin ALL = ALL
+EOF
+if [ $? -ne 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should match the 'ALL=(:staff) NOPASSWD: ALL' rule."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group -g staff \
+    admin /bin/ls <<'EOF'
+admin ALL = ALL
+ALL ALL=(:staff) NOPASSWD: ALL
+EOF
+if [ $? -ne 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should match the 'ALL=(:staff) NOPASSWD: ALL' rule."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group -g staff \
+    admin /bin/ls <<'EOF'
+ALL ALL=(:staff) NOPASSWD: ALL
+admin ALL = ALL
+EOF
+if [ $? -ne 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should match the 'ALL=(:staff) NOPASSWD: ALL' rule."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group -u admin \
+    admin /bin/ls <<'EOF'
+ALL ALL=(:staff) NOPASSWD: ALL
+admin ALL = ALL
+EOF
+if [ $? -ne 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should match the 'ALL=(:staff) NOPASSWD: ALL' rule."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group -u admin -g staff \
+    admin /bin/ls <<'EOF'
+ALL ALL=(:staff) NOPASSWD: ALL
+admin ALL = ALL
+EOF
+if [ $? -ne 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should not match any rules."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group -g guest \
+    admin /bin/ls <<'EOF'
+ALL ALL=(:staff) NOPASSWD: ALL
+admin ALL = ALL
+EOF
+if [ $? -eq 0 ]; then
+    status=1
+fi
+
+echo ""
+echo "This should not match any rules."
+$TESTSUDOERS -p ${TESTDIR}/passwd -P ${TESTDIR}/group -u root -g users \
+    admin /bin/ls <<'EOF'
+ALL ALL=(:users) NOPASSWD: ALL
+admin ALL = ALL
+EOF
+if [ $? -eq 0 ]; then
+    status=1
+fi
+
+exit $status