[LTP] [PATCH v2 4/4] syscalls/pidfd_send_signal03

Christian Amann
2019-06-04T11:47:02Z

Add testcase to check if the syscall will send a signal
to a process with the same PID as the targeted process.

Signed-off-by: Christian Amann <camann@suse.com>
---
runtest/syscalls | 1 +
.../kernel/syscalls/pidfd_send_signal/.gitignore | 1 +
.../pidfd_send_signal/pidfd_send_signal03.c | 142 +++++++++++++++++++++
3 files changed, 144 insertions(+)
create mode 100644 testcases/kernel/syscalls/pidfd_send_signal/pidfd_send_signal03.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 90a1cf8e6..7274c7741 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -838,6 +838,7 @@ personality02 personality02

pidfd_send_signal01 pidfd_send_signal01
pidfd_send_signal02 pidfd_send_signal02
+pidfd_send_signal03 pidfd_send_signal03

pipe01 pipe01
pipe02 pipe02
diff --git a/testcases/kernel/syscalls/pidfd_send_signal/.gitignore b/testcases/kernel/syscalls/pidfd_send_signal/.gitignore
index 6ea6401a8..cba7d50a4 100644
--- a/testcases/kernel/syscalls/pidfd_send_signal/.gitignore
+++ b/testcases/kernel/syscalls/pidfd_send_signal/.gitignore
@@ -1,2 +1,3 @@
/pidfd_send_signal01
/pidfd_send_signal02
+/pidfd_send_signal03
diff --git a/testcases/kernel/syscalls/pidfd_send_signal/pidfd_send_signal03.c b/testcases/kernel/syscalls/pidfd_send_signal/pidfd_send_signal03.c
new file mode 100644
index 000000000..a04d59ef2
--- /dev/null
+++ b/testcases/kernel/syscalls/pidfd_send_signal/pidfd_send_signal03.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 SUSE LLC
+ * Author: Christian Amann <camann@suse.com>
+ */
+/*
+ * This test checks if the pidfd_send_signal syscall wrongfully sends
+ * a signal to a new process which inherited the PID of the actual
+ * target process.
+ * In order to do so it is necessary to start a process with a pre-
+ * determined PID. This is accomplished by writing to the
+ * /proc/sys/kernel/ns_last_pid file.
+ * By utilizing this, this test forks two children with the same PID.
+ * It is then checked, if the syscall will send a signal to the second
+ * child using the pidfd of the first one.
+ */
+
+#define _GNU_SOURCE
+
+#include <signal.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "pidfd_send_signal.h"
+#include "tst_safe_pthread.h"
+//#include "tst_safe_file_ops.h"
+
+#define PIDTRIES 3
+
+static char *last_pid_file;
+static int pidfd, new_pidfd;
+static int old_inode, new_inode;
+
+static int get_inode_number(int fd)
+{
+ struct stat file_stat;
+
+ SAFE_FSTAT(fd, &file_stat);
+ return file_stat.st_ino;
+}
+
+static void verify_pidfd_send_signal(void)
+{
+ pid_t pid, new_pid;
+ char pid_filename[32];
+ char pid_str[16];
+ int i, fail;
+
+ fail = 1;
+ for (i = 0; i < PIDTRIES; i++) {
+ pid = SAFE_FORK();
+ if (pid == 0) {
+ TST_CHECKPOINT_WAIT(0);
+ return;
+ }
+
+ sprintf(pid_filename, "/proc/%d", pid);
+ pidfd = SAFE_OPEN(pid_filename, O_DIRECTORY | O_CLOEXEC);
+ old_inode = get_inode_number(pidfd);
+
+ TST_CHECKPOINT_WAKE(0);
+ tst_reap_children();
+
+ /* Manipulate PID for next process */
+ sprintf(pid_str, "%d", pid - 1);
+ SAFE_FILE_PRINTF(last_pid_file, pid_str);
+
+ new_pid = SAFE_FORK();
+ if (new_pid == 0) {
+ TST_CHECKPOINT_WAIT(0);
+ return;
+ }
+
+ if (new_pid == pid) {
+ new_pidfd = SAFE_OPEN(pid_filename,
+ O_DIRECTORY | O_CLOEXEC);
+ new_inode = get_inode_number(new_pidfd);
+ SAFE_CLOSE(new_pidfd);
+ fail = 0;
+ break;
+ }
+
+ if (i < PIDTRIES) {
+ tst_res(TINFO,
+ "Failed to set correct PID, trying again...");
+ }
+ SAFE_CLOSE(pidfd);
+ TST_CHECKPOINT_WAKE(0);
+ tst_reap_children();
+ }
+ if (fail) {
+ tst_brk(TBROK,
+ "Could not set new child to same PID as the old one!");
+ }
+ if (old_inode == new_inode) {
+ tst_res(TWARN,
+ "File descriptor of new process points to the inode "
+ "of the old process!");
+ }
+
+ TEST(pidfd_send_signal(pidfd, SIGUSR1, NULL, 0));
+ if (TST_RET == -1 && TST_ERR == ESRCH) {
+ tst_res(TPASS,
+ "Did not send signal to wrong process with same PID!");
+ } else {
+ tst_res(TFAIL | TTERRNO,
+ "pidf_send_signal() ended unexpectedly - return value: %ld, error",
+ TST_RET);
+ }
+ TST_CHECKPOINT_WAKE(0);
+ tst_reap_children();
+
+ SAFE_CLOSE(pidfd);
+}
+
+static void setup(void)
+{
+ check_syscall_support();
+
+ last_pid_file = "/proc/sys/kernel/ns_last_pid";
+ if (access(last_pid_file, F_OK) == -1) {
+ tst_brk(TCONF, "%s does not exist, cannot set PIDs",
+ last_pid_file);
+ }
+}
+
+static void cleanup(void)
+{
+ tst_reap_children();
+ if (new_pidfd > 0)
+ SAFE_CLOSE(new_pidfd);
+ if (pidfd > 0)
+ SAFE_CLOSE(pidfd);
+}
+
+static struct tst_test test = {
+ .test_all = verify_pidfd_send_signal,
+ .setup = setup,
+ .cleanup = cleanup,
+ .needs_root = 1,
+ .needs_checkpoints = 1,
+ .forks_child = 1,
+};
--
2.16.4