[PATCH bpf 3/4] tools/testing: add test for NS_GET_COOKIE

[Lorenz Bauer <lmb@cloudflare.com>]

Check that NS_GET_COOKIE returns a non-zero value, and that distinct
network namespaces have different cookies.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
---
 tools/testing/selftests/nsfs/.gitignore |  1 +
 tools/testing/selftests/nsfs/Makefile   |  2 +-
 tools/testing/selftests/nsfs/netns.c    | 57 +++++++++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/nsfs/netns.c

diff --git a/tools/testing/selftests/nsfs/.gitignore b/tools/testing/selftests/nsfs/.gitignore
index ed79ebdf286e..ca31b216215b 100644
--- a/tools/testing/selftests/nsfs/.gitignore
+++ b/tools/testing/selftests/nsfs/.gitignore
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 owner
 pidns
+netns
diff --git a/tools/testing/selftests/nsfs/Makefile b/tools/testing/selftests/nsfs/Makefile
index dd9bd50b7b93..93793cdb5a7c 100644
--- a/tools/testing/selftests/nsfs/Makefile
+++ b/tools/testing/selftests/nsfs/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
-TEST_GEN_PROGS := owner pidns
+TEST_GEN_PROGS := owner pidns netns
 
 CFLAGS := -Wall -Werror
 
diff --git a/tools/testing/selftests/nsfs/netns.c b/tools/testing/selftests/nsfs/netns.c
new file mode 100644
index 000000000000..8ab862667b45
--- /dev/null
+++ b/tools/testing/selftests/nsfs/netns.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+
+#define NSIO    0xb7
+#define NS_GET_COOKIE   _IO(NSIO, 0x5)
+
+#define pr_err(fmt, ...) \
+		({ \
+			fprintf(stderr, "%s:%d:" fmt ": %m\n", \
+				__func__, __LINE__, ##__VA_ARGS__); \
+			1; \
+		})
+
+int main(int argc, char *argvp[])
+{
+	uint64_t cookie1, cookie2;
+	char path[128];
+	int ns;
+
+	snprintf(path, sizeof(path), "/proc/%d/ns/net", getpid());
+	ns = open(path, O_RDONLY);
+	if (ns < 0)
+		return pr_err("Unable to open %s", path);
+
+	if (ioctl(ns, NS_GET_COOKIE, &cookie1))
+		return pr_err("Unable to get first namespace cookie");
+
+	if (!cookie1)
+		return pr_err("NS_GET_COOKIE returned zero first cookie");
+
+	close(ns);
+	if (unshare(CLONE_NEWNET))
+		return pr_err("unshare");
+
+	ns = open(path, O_RDONLY);
+	if (ns < 0)
+		return pr_err("Unable to open %s", path);
+
+	if (ioctl(ns, NS_GET_COOKIE, &cookie2))
+		return pr_err("Unable to get second namespace cookie");
+
+	if (!cookie2)
+		return pr_err("NS_GET_COOKIE returned zero second cookie");
+
+	if (cookie1 == cookie2)
+		return pr_err("NS_GET_COOKIE returned identical cookies for distinct ns");
+
+	close(ns);
+	return 0;
+}
-- 
2.27.0