From 61b010c25a969bf0fd8af4441635d395b5fdcac6 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@osmocom.org>
Date: Sat, 11 Apr 2020 12:14:56 +0200
Subject: [PATCH] lib/netns: OSMO_ASSERT() if user doesn't call init_netns()

It is vital that init_netns() is called first in order to initialize
default_nsfd.

Change-Id: Ic16646fa7d60c578056b17351c5fe2090a81dff0
---
 lib/netns.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/netns.c b/lib/netns.c
index 1e77a04..6e0e179 100644
--- a/lib/netns.c
+++ b/lib/netns.c
@@ -40,12 +40,14 @@
 #include <fcntl.h>
 #include <errno.h>
 
+#include <osmocom/core/utils.h>
+
 #include "netns.h"
 
 #define NETNS_PATH "/var/run/netns"
 
 /*! default namespace of the GGSN process */
-static int default_nsfd;
+static int default_nsfd = -1;
 
 /*! switch to a (non-default) namespace, store existing signal mask in oldmask.
  *  \param[in] nsfd file descriptor representing the namespace to whch we shall switch
@@ -56,6 +58,8 @@ int switch_ns(int nsfd, sigset_t *oldmask)
 	sigset_t intmask;
 	int rc;
 
+	OSMO_ASSERT(default_nsfd >= 0);
+
 	if (sigfillset(&intmask) < 0)
 		return -errno;
 	if ((rc = sigprocmask(SIG_BLOCK, &intmask, oldmask)) != 0)
@@ -71,6 +75,8 @@ int switch_ns(int nsfd, sigset_t *oldmask)
  *  \returns 0 on successs; negative errno value in case of error */
 int restore_ns(sigset_t *oldmask)
 {
+	OSMO_ASSERT(default_nsfd >= 0);
+
 	int rc;
 	if (setns(default_nsfd, CLONE_NEWNET) < 0)
 		return -errno;
@@ -87,6 +93,8 @@ int open_ns(int nsfd, const char *pathname, int flags)
 	int fd;
 	int rc;
 
+	OSMO_ASSERT(default_nsfd >= 0);
+
 	/* mask off all signals, store old signal mask */
 	if (sigfillset(&intmask) < 0)
 		return -errno;
@@ -127,6 +135,8 @@ int socket_ns(int nsfd, int domain, int type, int protocol)
 	int sk;
 	int rc;
 
+	OSMO_ASSERT(default_nsfd >= 0);
+
 	/* mask off all signals, store old signal mask */
 	if (sigfillset(&intmask) < 0)
 		return -errno;
@@ -177,6 +187,8 @@ int get_nsfd(const char *name)
 	sigset_t intmask, oldmask;
 	char path[MAXPATHLEN] = NETNS_PATH;
 
+	OSMO_ASSERT(default_nsfd >= 0);
+
 	/* create /var/run/netns, if it doesn't exist already */
 	rc = mkdir(path, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
 	if (rc < 0 && errno != EEXIST)