Re: [LTP] [PATCH] containers: added netns/netns_netlink.c

[chrubis@suse.cz]

Hi!
> * Tests a netlink interface inside a new network namespace
> 
> Signed-off-by: Matus Marhefka <mmarhefk@redhat.com>
> ---
>  runtest/containers                                |   1 +
>  testcases/kernel/containers/.gitignore            |   1 +
>  testcases/kernel/containers/netns/Makefile        |   2 +-
>  testcases/kernel/containers/netns/netns_netlink.c | 175 ++++++++++++++++++++++
>  4 files changed, 178 insertions(+), 1 deletion(-)
>  create mode 100644 testcases/kernel/containers/netns/netns_netlink.c
> 
> diff --git a/runtest/containers b/runtest/containers
> index 8e8e067..7d01a44 100644
> --- a/runtest/containers
> +++ b/runtest/containers
> @@ -28,6 +28,7 @@ netns_two_children_ns netns_two_children_ns
>  netns_crtchild_delchild netns_crtchild_delchild
>  netns_par_chld_ipv6 netns_par_chld_ipv6
>  netns_par_chld_ftp netns_par_chld_ftp.sh
> +netns_netlink netns_netlink
>  
>  shmnstest_none shmnstest none
>  shmnstest_clone shmnstest clone
> diff --git a/testcases/kernel/containers/.gitignore b/testcases/kernel/containers/.gitignore
> index 4a98373..95daf12 100644
> --- a/testcases/kernel/containers/.gitignore
> +++ b/testcases/kernel/containers/.gitignore
> @@ -3,3 +3,4 @@ mountns/mountns01
>  mountns/mountns02
>  mountns/mountns03
>  mountns/mountns04
> +netns/netns_netlink
> diff --git a/testcases/kernel/containers/netns/Makefile b/testcases/kernel/containers/netns/Makefile
> index cdda23b..eea0d88 100644
> --- a/testcases/kernel/containers/netns/Makefile
> +++ b/testcases/kernel/containers/netns/Makefile
> @@ -31,7 +31,7 @@ LDLIBS			+= -lclone
>  MAKE_TARGETS		:= netns_create_container netns_crtchild \
>  			   netns_crtchild_delchild netns_par_chld_ftp \
>  			   netns_par_chld_ipv6 netns_sysfsview \
> -			   netns_two_children_ns
> +			   netns_two_children_ns netns_netlink
>  
>  $(MAKE_TARGETS): %: common.o %.o
>  
> diff --git a/testcases/kernel/containers/netns/netns_netlink.c b/testcases/kernel/containers/netns/netns_netlink.c
> new file mode 100644
> index 0000000..5f5d41f
> --- /dev/null
> +++ b/testcases/kernel/containers/netns/netns_netlink.c
> @@ -0,0 +1,175 @@
> +/* Copyright (c) 2014 Red Hat, Inc.
> + *
> + * This program is free software: you can redistribute it and/or modify
> + * it under the terms of version 2 the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program 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 General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + ***********************************************************************
> + * File: netns_netlink.c
> + *
> + * Tests a netlink interface inside a new network namespace.
> + * Description:
> + * 1. Unshares a network namespace (so network related actions
> + *    have no effect on a real system)
> + * 2. Forks a child which creates a NETLINK_ROUTE netlink socket
> + *    and listens to RTMGRP_LINK (network interface create/delete/up/down)
> + *    multicast group.
> + * 4. Child then waits for parent approval to receive data from socket
> + * 3. Parent creates a new TAP interface (dummy0) and immediately
> + *    removes it (which should generate some data in child's netlink socket).
> + *    Then it allows child to continue.
> + * 4. As the child was listening to RTMGRP_LINK multicast group, it should
> + *    detect the new interface creation (by reading data from netlink socket),
> + *    if so, the test passes, otherwise it fails.
> + */
> +
> +#define _GNU_SOURCE
> +#include <sys/wait.h>
> +#include <asm/types.h>
> +#include <sys/socket.h>
> +#include <linux/netlink.h>
> +#include <linux/rtnetlink.h>
> +#include <unistd.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <errno.h>
> +#include "usctest.h"
> +#include "test.h"
> +#include "safe_macros.h"
> +#include "netns_helper.h"
> +
> +
> +char *TCID	= "netns_netlink";
> +int TST_TOTAL	= 1;
> +int pipefd[2];
> +
> +
> +static void cleanup(void)
> +{
> +	close(pipefd[0]);
> +	close(pipefd[1]);
> +}
> +
> +static void setup(void)
> +{
> +	tst_require_root(NULL);
> +	check_netns();
> +}
> +
> +int child_func(void)
> +{
> +	int fd, len;
> +	struct sockaddr_nl sa;
> +	char c, buffer[4096];
> +	struct nlmsghdr *nlh;
> +
> +	/* child will listen to a network interface create/delete/up/down
> +	 * events */
> +	memset(&sa, 0, sizeof(sa));
> +	sa.nl_family = AF_NETLINK;
> +	sa.nl_groups = RTMGRP_LINK;
> +	
> +	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
> +	if (fd == -1) {
> +		perror("socket");
> +		return 1;
> +	}
> +	if (bind(fd, (struct sockaddr *) &sa, sizeof(sa)) == -1) {
> +		perror("bind");
> +		return 1;
> +	}
> +
> +	/* waits for parent to create an interface */
> +	read(pipefd[0], &c, 1);
> +
> +	nlh = (struct nlmsghdr *) buffer;
> +	/* non-blocking recv call */
> +	while ((len = recv(fd, nlh, sizeof(buffer), MSG_DONTWAIT)) > 0) {
> +		/* stop receiving only on interface create event */
> +		if (nlh->nlmsg_type == RTM_NEWLINK)
> +			break;
> +	}
> +
> +	if (len == -1) {
> +		perror("recv");
> +		return 1;
> +	}
> +
> +	return 0;
> +}
> +
> +static void test(void)
> +{
> +	pid_t pid;
> +	int status;
> +
> +	/* creates a pipe for synchronization between parent and child */
> +	SAFE_PIPE(cleanup, pipefd);

Use the CHECKPOINT interface instead.

> +	/* unshares the network namespace */
> +	if (unshare(CLONE_NEWNET) == -1)
> +		tst_brkm(TBROK | TERRNO, cleanup, "unshare failed");
> +
> +	pid = fork();

Use tst_fork() instead.

> +	if (pid < 0) {  /* error */
> +		tst_brkm(TBROK | TERRNO, cleanup, "fork failed");
> +	}
> +	if (pid == 0) { /* child */
> +		_exit(child_func());
> +	}
> +
> +	/* parent */

No obvious comments like /* error */, /* child */, /* parent */, etc.
please.

> +	/* creates TAP network interface dummy0 */
> +	if (system("ip tuntap add dev dummy0 mode tap") == -1)
> +		tst_brkm(TBROK | TERRNO, cleanup, "system failed");
> +
> +	/* removes previously created dummy0 device */
> +	if (system("ip tuntap del mode tap dummy0") == -1)
> +		tst_brkm(TBROK | TERRNO, cleanup, "system failed");
> +
> +	/* allow child to continue */
> +	SAFE_WRITE(cleanup, 0, pipefd[1], "0", 1);
> +
> +
> +	SAFE_WAITPID(cleanup, pid, &status, 0);
> +	if (WIFEXITED(status) && WEXITSTATUS(status) != 0) {
> +		tst_resm(TFAIL, "netlink interface fail");
> +		return;
> +	}
> +	if (WIFSIGNALED(status)) {
> +		tst_resm(TFAIL, "child was killed with signal %s",
> +			 tst_strsig(WTERMSIG(status)));
> +		return;
> +	}
> +
> +	tst_resm(TPASS, "netlink interface pass");
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	const char *msg;
> +	int lc;
> +
> +	msg = parse_opts(argc, argv, NULL, NULL);
> +	if (msg != NULL)
> +		tst_brkm(TBROK, NULL, "OPTION PARSING ERROR - %s", msg);
> +
> +	setup();
> +
> +	for (lc = 0; TEST_LOOPING(lc); lc++) {
> +		test();
> +		cleanup();
> +		/* To get rid of "resource temporarily unavalable" errors
> +		 * when testing with -i option */
> +		sleep(1);

		I do not like this sleep(), moreover looking into the
		child_func() you forget to close the socked fd, is this
		still needed even if the fd is closed there?
> +	}
> +
> +	tst_exit();
> +}

-- 
Cyril Hrubis
chrubis@suse.cz

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