Commit 3084097c authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Daniel Borkmann
Browse files

selftests/bpf: Remove the "/sys" mount and umount dance in {open,close}_netns 



The previous patches have removed the need to do the mount and umount
dance when switching netns. In particular:
* Avoid remounting /sys/fs/bpf to have a clean start
* Avoid remounting /sys to get a ifindex of a particular netns

This patch can finally remove the mount and umount dance in
{open,close}_netns which is unnecessarily complicated and
error-prone.

Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20221129070900.3142427-6-martin.lau@linux.dev
parent 5dc42a7f

tools/testing/selftests/bpf/network_helpers.c

+5 −46
Original line number Diff line number Diff line
@@ -390,49 +390,6 @@ struct nstoken { 
	int orig_netns_fd;

};



static int setns_by_fd(int nsfd)

{

	int err;



	err = setns(nsfd, CLONE_NEWNET);

	close(nsfd);



	if (!ASSERT_OK(err, "setns"))

		return err;



	/* Switch /sys to the new namespace so that e.g. /sys/class/net

	 * reflects the devices in the new namespace.

	 */

	err = unshare(CLONE_NEWNS);

	if (!ASSERT_OK(err, "unshare"))

		return err;



	/* Make our /sys mount private, so the following umount won't

	 * trigger the global umount in case it's shared.

	 */

	err = mount("none", "/sys", NULL, MS_PRIVATE, NULL);

	if (!ASSERT_OK(err, "remount private /sys"))

		return err;



	err = umount2("/sys", MNT_DETACH);

	if (!ASSERT_OK(err, "umount2 /sys"))

		return err;



	err = mount("sysfs", "/sys", "sysfs", 0, NULL);

	if (!ASSERT_OK(err, "mount /sys"))

		return err;



	err = mount("bpffs", "/sys/fs/bpf", "bpf", 0, NULL);

	if (!ASSERT_OK(err, "mount /sys/fs/bpf"))

		return err;



	err = mount("debugfs", "/sys/kernel/debug", "debugfs", 0, NULL);

	if (!ASSERT_OK(err, "mount /sys/kernel/debug"))

		return err;



	return 0;

}



struct nstoken *open_netns(const char *name)

{

	int nsfd;
@@ -453,8 +410,9 @@ struct nstoken *open_netns(const char *name) 
	if (!ASSERT_GE(nsfd, 0, "open netns fd"))

		goto fail;



	err = setns_by_fd(nsfd);

	if (!ASSERT_OK(err, "setns_by_fd"))

	err = setns(nsfd, CLONE_NEWNET);

	close(nsfd);

	if (!ASSERT_OK(err, "setns"))

		goto fail;



	return token;
@@ -465,6 +423,7 @@ struct nstoken *open_netns(const char *name) 


void close_netns(struct nstoken *token)

{

	ASSERT_OK(setns_by_fd(token->orig_netns_fd), "setns_by_fd");

	ASSERT_OK(setns(token->orig_netns_fd, CLONE_NEWNET), "setns");

	close(token->orig_netns_fd);

	free(token);

}