Add tests for pdrfork

MFC With:	5c2ee618d5
Sponsored by:	ConnectWise

tests/sys/kern/Makefile

@@ -29,6 +29,7 @@ ATF_TESTS_C+=	ktls_test
 ATF_TESTS_C+=	ktrace_test
 ATF_TESTS_C+=	listener_wakeup
 ATF_TESTS_C+=	module_test
+ATF_TESTS_C+=	pdrfork
 ATF_TESTS_C+=	prace
 ATF_TESTS_C+=	procdesc
 ATF_TESTS_C+=	ptrace_test

tests/sys/kern/pdrfork.c

@@ -0,0 +1,187 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2026 ConnectWise
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/user.h>
+#include <sys/procdesc.h>
+#include <sys/wait.h>
+
+#include <atf-c.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+static void basic_usage(int rfflags) {
+	int pd = -1;
+	pid_t pid, pd_pid, waited_pid;
+	int r, status;
+
+	pid = pdrfork(&pd, 0, rfflags);
+	ATF_REQUIRE_MSG(pid >= 0, "rfork failed with %s", strerror(errno));
+	if (pid == 0) {
+		/* In child */
+		_exit(0);
+	}
+	ATF_REQUIRE_MSG(pd >= 0, "rfork did not return a process descriptor");
+	r = pdgetpid(pd, &pd_pid);
+	ATF_CHECK_EQ_MSG(r, 0, "pdgetpid failed: %s", strerror(errno));
+
+	/* We should be able to collect the child's status */
+	waited_pid = waitpid(pid, &status, WEXITED | WNOWAIT);
+	ATF_CHECK_EQ(waited_pid, pid);
+
+	/* But after closing the process descriptor, we won't */
+	close(pd);
+	waited_pid = waitpid(pid, &status, WEXITED | WNOHANG);
+	ATF_CHECK_EQ(-1, waited_pid);
+	ATF_CHECK_EQ(ECHILD, errno);
+}
+
+/* pdrfork does not return a process descriptor to the child */
+ATF_TC_WITHOUT_HEAD(child_gets_no_pidfd);
+ATF_TC_BODY(child_gets_no_pidfd, tc)
+{
+	int pd = -1;
+	pid_t pid, pd_pid, waited_pid;
+	int r, status;
+
+	pid = pdrfork(&pd, 0, RFPROC | RFPROCDESC);
+	ATF_REQUIRE_MSG(pid >= 0, "rfork failed with %s", strerror(errno));
+	if (pid == 0) {
+		/*
+		 * In child.  We can't do very much here before we exec, so
+		 * just use our exit status to report success.
+		 */
+		_exit(pd == -1);
+	}
+	ATF_REQUIRE_MSG(pd >= 0, "rfork did not return a process descriptor");
+	r = pdgetpid(pd, &pd_pid);
+	ATF_CHECK_EQ_MSG(r, 0, "pdgetpid failed: %s", strerror(errno));
+
+	waited_pid = waitpid(pid, &status, WEXITED | WNOWAIT);
+	ATF_CHECK_EQ(waited_pid, pid);
+	ATF_REQUIRE(WIFEXITED(status) && (WEXITSTATUS(status) == true));
+
+	close(pd);
+}
+
+/* If the pidfd argument is invalid, the error should be handled gracefully */
+ATF_TC_WITHOUT_HEAD(efault);
+ATF_TC_BODY(efault, tc)
+{
+	ATF_REQUIRE_ERRNO(EFAULT, pdrfork((int*)-1, 0, RFPROC | RFPROCDESC) < 0);
+}
+
+/* Invalid combinations of flags should return EINVAL */
+ATF_TC_WITHOUT_HEAD(einval);
+ATF_TC_BODY(einval, tc)
+{
+	int pd = -1;
+
+	ATF_CHECK_ERRNO(EINVAL, pdrfork(&pd, -1, RFSPAWN) < 0);
+	ATF_CHECK_ERRNO(EINVAL, pdrfork(&pd, 0, -1) < 0);
+	ATF_CHECK_ERRNO(EINVAL, pdrfork(&pd, 0, RFSPAWN | RFNOWAIT) < 0);
+	ATF_CHECK_ERRNO(EINVAL, pdrfork(&pd, 0, RFPROC | RFFDG| RFCFDG) < 0);
+	ATF_CHECK_ERRNO(EINVAL, pdrfork(&pd, 0, RFPROCDESC) < 0);
+}
+
+/*
+ * Without RFSPAWN, RFPROC, or RFPROCDESC, an existing process may be modified
+ */
+ATF_TC_WITHOUT_HEAD(modify_child);
+ATF_TC_BODY(modify_child, tc)
+{
+	int fdp = -1;
+	pid_t pid1, pid2;
+
+	pid1 = pdfork(&fdp, 0);
+	if (pid1 == 0)
+		_exit(0);
+	ATF_REQUIRE_MSG(pid1 >= 0, "pdfork failed: %s", strerror(errno));
+	ATF_REQUIRE_MSG(fdp >= 0, "pdfork didn't return a process descriptor");
+
+	pid2 = pdrfork(&fdp, 0, RFNOWAIT);
+	ATF_REQUIRE_MSG(pid2 >= 0, "pdrfork failed: %s", strerror(errno));
+	ATF_CHECK_EQ_MSG(pid2, 0,
+	    "pdrfork created a process even though we told it not to");
+
+	close(fdp);
+}
+
+/*
+ * Basic usage with RFPROC.  No process descriptor will be created.
+ * I'm not sure why you would use pdrfork in this case instead of plain rfork
+ */
+ATF_TC_WITHOUT_HEAD(rfproc);
+ATF_TC_BODY(rfproc, tc)
+{
+	int pd = -1;
+	pid_t pid;
+
+	pid = pdrfork(&pd, 0, RFPROC);
+	ATF_REQUIRE_MSG(pid > 0, "rfork failed with %s", strerror(errno));
+	if (pid == 0)
+		_exit(0);
+
+	ATF_REQUIRE_EQ_MSG(pd, -1,
+	    "rfork(RFPROC) returned a process descriptor");
+}
+
+/* basic usage with RFPROCDESC */
+ATF_TC_WITHOUT_HEAD(rfprocdesc);
+ATF_TC_BODY(rfprocdesc, tc)
+{
+	basic_usage(RFPROC | RFPROCDESC);
+}
+
+/* basic usage with RFSPAWN */
+/*
+ * Skip on i386 and x86_64 because RFSPAWN cannot be used from C code on those
+ * architectures.  See lib/libc/gen/posix_spawn.c for details.
+ */
+#if !(defined(__i386__)) && !(defined(__amd64__))
+ATF_TC_WITHOUT_HEAD(rfspawn);
+ATF_TC_BODY(rfspawn, tc)
+{
+	basic_usage(RFSPAWN);
+}
+#endif
+
+ATF_TP_ADD_TCS(tp)
+{
+	ATF_TP_ADD_TC(tp, child_gets_no_pidfd);
+	ATF_TP_ADD_TC(tp, efault);
+	ATF_TP_ADD_TC(tp, einval);
+	ATF_TP_ADD_TC(tp, modify_child);
+	ATF_TP_ADD_TC(tp, rfproc);
+	ATF_TP_ADD_TC(tp, rfprocdesc);
+#if !(defined(__i386__)) && !(defined(__amd64__))
+	ATF_TP_ADD_TC(tp, rfspawn);
+#endif
+
+	return (atf_no_error());
+}