socket: Add a test for MSG_CMSG_CLOEXEC

This checks that:
* We can send and receive fds over Unix domain sockets using SCM_RIGHTS;
* msg_controllen, cmsg_level, cmsg_type, cmsg_len are all filled in
  correctly on receive;
* Most importantly, the received fd has or has not the close-on-exec
  flag set depending on whether we pass MSG_CMSG_CLOEXEC to recvmsg ().

Checked on i686-gnu and x86_64-linux-gnu.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230423160548.126576-4-bugaevc@gmail.com>
This commit is contained in:
Sergey Bugaev 2023-04-23 19:05:48 +03:00 committed by Samuel Thibault
parent 323fe6a1a9
commit 904b94c07a
2 changed files with 127 additions and 0 deletions

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@ -35,6 +35,7 @@ tests := \
tst-accept4 \
tst-sockopt \
tst-cmsghdr \
tst-cmsg_cloexec \
# tests
tests-internal := \

126
socket/tst-cmsg_cloexec.c Normal file
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@ -0,0 +1,126 @@
/* Smoke test for MSG_CMSG_CLOEXEC.
Copyright (C) 2021-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <support/xunistd.h>
#include <support/check.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <string.h>
#include <fcntl.h>
static void
send_fd (int sockfd, int fd)
{
char data[] = "hello";
struct iovec iov = { .iov_base = data, .iov_len = sizeof (data) };
union
{
struct cmsghdr header;
char bytes[CMSG_SPACE (sizeof (fd))];
} cmsg_storage;
struct msghdr msg =
{
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = cmsg_storage.bytes,
.msg_controllen = sizeof (cmsg_storage)
};
memset (&cmsg_storage, 0, sizeof (cmsg_storage));
struct cmsghdr *cmsg = CMSG_FIRSTHDR (&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN (sizeof (fd));
memcpy (CMSG_DATA (cmsg), &fd, sizeof (fd));
ssize_t nsent = sendmsg (sockfd, &msg, 0);
if (nsent < 0)
FAIL_EXIT1 ("sendmsg (%d): %m", sockfd);
TEST_COMPARE (nsent, sizeof (data));
}
static int
recv_fd (int sockfd, int flags)
{
char buffer[100];
struct iovec iov = { .iov_base = buffer, .iov_len = sizeof (buffer) };
union
{
struct cmsghdr header;
char bytes[100];
} cmsg_storage;
struct msghdr msg =
{
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = cmsg_storage.bytes,
.msg_controllen = sizeof (cmsg_storage)
};
ssize_t nrecv = recvmsg (sockfd, &msg, flags);
if (nrecv < 0)
FAIL_EXIT1 ("recvmsg (%d): %m", sockfd);
TEST_COMPARE (msg.msg_controllen, CMSG_SPACE (sizeof (int)));
struct cmsghdr *cmsg = CMSG_FIRSTHDR (&msg);
TEST_COMPARE (cmsg->cmsg_level, SOL_SOCKET);
TEST_COMPARE (cmsg->cmsg_type, SCM_RIGHTS);
TEST_COMPARE (cmsg->cmsg_len, CMSG_LEN (sizeof (int)));
int fd;
memcpy (&fd, CMSG_DATA (cmsg), sizeof (fd));
return fd;
}
static int
do_test (void)
{
int sockfd[2];
int newfd;
int flags;
int rc = socketpair (AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0, sockfd);
if (rc < 0)
FAIL_EXIT1 ("socketpair: %m");
send_fd (sockfd[1], STDIN_FILENO);
newfd = recv_fd (sockfd[0], 0);
TEST_VERIFY_EXIT (newfd > 0);
flags = fcntl (newfd, F_GETFD, 0);
TEST_VERIFY_EXIT (flags != -1);
TEST_VERIFY (!(flags & FD_CLOEXEC));
xclose (newfd);
send_fd (sockfd[1], STDIN_FILENO);
newfd = recv_fd (sockfd[0], MSG_CMSG_CLOEXEC);
TEST_VERIFY_EXIT (newfd > 0);
flags = fcntl (newfd, F_GETFD, 0);
TEST_VERIFY_EXIT (flags != -1);
TEST_VERIFY (flags & FD_CLOEXEC);
xclose (newfd);
xclose (sockfd[0]);
xclose (sockfd[1]);
return 0;
}
#include <support/test-driver.c>