zdtm: Add sock_peercred test

Check that SO_PEERCRED socket options restored correctly.
Now it's not supported, thus test is marked as "noauto".

(It seems support of this feature will require "ghost tasks",
when we introduce them).

travis-ci: success for zdtm: Add sock_peercred test
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/static/Makefile

@@ -155,6 +155,7 @@ TST_NOFILE	:=				\
 		clone_fs			\
 		macvlan			\
 		cr_veth				\
+		sock_peercred			\
 #		jobctl00			\
 
 ifneq ($(SRCARCH),arm)

test/zdtm/static/sock_peercred.c

@@ -0,0 +1,124 @@
+#define _GNU_SOURCE
+#include <sched.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <stdio.h>
+
+#include "zdtmtst.h"
+
+#define STACK_SIZE (1024 * 1024)
+#define GID_INC 1
+#define UID_INC 1
+
+const char *test_doc    = "Check peercred of a unix socket remains the same";
+const char *test_author = "Kirill Tkhai <ktkhai@virtuozzo.com>";
+
+static int child_func(void *fd_p)
+{
+	int fd = (int)(unsigned long)fd_p;
+	struct ucred ucred;
+	socklen_t len;
+	int sks[2];
+
+	if (setgid(getgid() + GID_INC) != 0) {
+		pr_perror("Can't setgid()");
+		return 1;
+	}
+
+	if (setuid(getuid() + UID_INC) != 0) {
+		pr_perror("Can't setuid()");
+		return 1;
+	}
+
+	if (socketpair(PF_UNIX, SOCK_DGRAM | SOCK_NONBLOCK, 0, sks) < 0) {
+		pr_perror("Can't create socketpair");
+		return 1;
+	}
+
+	len = sizeof(ucred);
+	if (getsockopt(sks[0], SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
+		pr_perror("Can't getsockopt()");
+		return 1;
+	}
+
+	if (ucred.pid != getpid() || ucred.uid != getuid() || ucred.gid != getgid()) {
+		pr_perror("Wrong sockopts");
+		return 1;
+	}
+
+	/* If sks[1] == fd, the below closes it, but we don't care */
+	if (dup2(sks[0], fd) == -1) {
+		pr_perror("Can't dup fd\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	struct ucred ucred;
+	int fd, status;
+	socklen_t len;
+	char *stack;
+	pid_t pid;
+
+	test_init(argc, argv);
+
+	/*
+	 * We do not know, which direction stack grows.
+	 * So just allocate 2 * STACK_SIZE for stack and
+	 * give clone() pointer to middle of this memory.
+	 */
+	stack = malloc(2 * STACK_SIZE);
+	if (!stack) {
+		pr_err("malloc\n");
+		return 1;
+	}
+
+	/* Find unused fd */
+	for (fd = 0; fd < INT_MAX; fd++) {
+		if (fcntl(fd, F_GETFD) == -1 && errno == EBADF)
+			break;
+	}
+
+	if (fd == INT_MAX) {
+		pr_err("INT_MAX happens...\n");
+		return 1;
+	}
+
+	pid = clone(child_func, stack + STACK_SIZE, CLONE_FILES|SIGCHLD, (void *)(unsigned long)fd);
+	if (pid == -1) {
+		pr_perror("clone");
+		return 1;
+	}
+
+	if (wait(&status) == -1 || status) {
+		pr_perror("wait error: status=%d\n", status);
+		return 1;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	len = sizeof(ucred);
+	if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
+		fail("Can't getsockopt()");
+		return 1;
+	}
+
+	if (ucred.pid != pid || ucred.gid != getuid() + UID_INC ||
+			        ucred.gid != getgid() + GID_INC) {
+		fail("Wrong pid, uid or gid\n");
+		return 1;
+	}
+
+	pass();
+	return 0;
+}

test/zdtm/static/sock_peercred.desc

@@ -0,0 +1 @@
+{ 'flags': 'suid noauto' }