selftests/bpf: Move open_netns() and close_netns() into network_helpers.c

These will also be used by the xdp_do_redirect test being added in the next
commit.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220309105346.100053-5-toke@redhat.com

1 files changed, 86 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 6db1af8fdee7..2bb1f9b3841d 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -1,18 +1,25 @@
 // SPDX-License-Identifier: GPL-2.0-only
+#define _GNU_SOURCE
+
 #include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
+#include <sched.h>
 
 #include <arpa/inet.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
 
 #include <linux/err.h>
 #include <linux/in.h>
 #include <linux/in6.h>
+#include <linux/limits.h>
 
 #include "bpf_util.h"
 #include "network_helpers.h"
+#include "test_progs.h"
 
 #define clean_errno() (errno == 0 ? "None" : strerror(errno))
 #define log_err(MSG, ...) ({						\
@@ -356,3 +363,82 @@ char *ping_command(int family)
 	}
 	return "ping";
 }
+
+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;
+
+	return 0;
+}
+
+struct nstoken *open_netns(const char *name)
+{
+	int nsfd;
+	char nspath[PATH_MAX];
+	int err;
+	struct nstoken *token;
+
+	token = malloc(sizeof(struct nstoken));
+	if (!ASSERT_OK_PTR(token, "malloc token"))
+		return NULL;
+
+	token->orig_netns_fd = open("/proc/self/ns/net", O_RDONLY);
+	if (!ASSERT_GE(token->orig_netns_fd, 0, "open /proc/self/ns/net"))
+		goto fail;
+
+	snprintf(nspath, sizeof(nspath), "%s/%s", "/var/run/netns", name);
+	nsfd = open(nspath, O_RDONLY | O_CLOEXEC);
+	if (!ASSERT_GE(nsfd, 0, "open netns fd"))
+		goto fail;
+
+	err = setns_by_fd(nsfd);
+	if (!ASSERT_OK(err, "setns_by_fd"))
+		goto fail;
+
+	return token;
+fail:
+	free(token);
+	return NULL;
+}
+
+void close_netns(struct nstoken *token)
+{
+	ASSERT_OK(setns_by_fd(token->orig_netns_fd), "setns_by_fd");
+	free(token);
+}