1 files changed, 145 insertions, 0 deletions
diff --git a/lib/namespace.c b/lib/namespace.c
new file mode 100644
index 0000000..45a7ded
--- /dev/null
+++ b/lib/namespace.c
@@ -0,0 +1,145 @@
+/*
+ * namespace.c
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+
+#include <sys/statvfs.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <limits.h>
+
+#include "utils.h"
+#include "namespace.h"
+
+static void bind_etc(const char *name)
+{
+	char etc_netns_path[sizeof(NETNS_ETC_DIR) + NAME_MAX];
+	char netns_name[PATH_MAX];
+	char etc_name[PATH_MAX];
+	struct dirent *entry;
+	DIR *dir;
+
+	if (strlen(name) >= NAME_MAX)
+		return;
+
+	snprintf(etc_netns_path, sizeof(etc_netns_path), "%s/%s", NETNS_ETC_DIR, name);
+	dir = opendir(etc_netns_path);
+	if (!dir)
+		return;
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (strcmp(entry->d_name, ".") == 0)
+			continue;
+		if (strcmp(entry->d_name, "..") == 0)
+			continue;
+		snprintf(netns_name, sizeof(netns_name), "%s/%s", etc_netns_path, entry->d_name);
+		snprintf(etc_name, sizeof(etc_name), "/etc/%s", entry->d_name);
+		if (mount(netns_name, etc_name, "none", MS_BIND, NULL) < 0) {
+			fprintf(stderr, "Bind %s -> %s failed: %s\n",
+				netns_name, etc_name, strerror(errno));
+		}
+	}
+	closedir(dir);
+}
+
+int netns_switch(char *name)
+{
+	char net_path[PATH_MAX];
+	int netns;
+	unsigned long mountflags = 0;
+	struct statvfs fsstat;
+
+	snprintf(net_path, sizeof(net_path), "%s/%s", NETNS_RUN_DIR, name);
+	netns = open(net_path, O_RDONLY | O_CLOEXEC);
+	if (netns < 0) {
+		fprintf(stderr, "Cannot open network namespace \"%s\": %s\n",
+			name, strerror(errno));
+		return -1;
+	}
+
+	if (setns(netns, CLONE_NEWNET) < 0) {
+		fprintf(stderr, "setting the network namespace \"%s\" failed: %s\n",
+			name, strerror(errno));
+		close(netns);
+		return -1;
+	}
+	close(netns);
+
+	if (unshare(CLONE_NEWNS) < 0) {
+		fprintf(stderr, "unshare failed: %s\n", strerror(errno));
+		return -1;
+	}
+	/* Don't let any mounts propagate back to the parent */
+	if (mount("", "/", "none", MS_SLAVE | MS_REC, NULL)) {
+		fprintf(stderr, "\"mount --make-rslave /\" failed: %s\n",
+			strerror(errno));
+		return -1;
+	}
+
+	/* Mount a version of /sys that describes the network namespace */
+
+	if (umount2("/sys", MNT_DETACH) < 0) {
+		/* If this fails, perhaps there wasn't a sysfs instance mounted. Good. */
+		if (statvfs("/sys", &fsstat) == 0) {
+			/* We couldn't umount the sysfs, we'll attempt to overlay it.
+			 * A read-only instance can't be shadowed with a read-write one. */
+			if (fsstat.f_flag & ST_RDONLY)
+				mountflags = MS_RDONLY;
+		}
+	}
+	if (mount(name, "/sys", "sysfs", mountflags, NULL) < 0) {
+		fprintf(stderr, "mount of /sys failed: %s\n",strerror(errno));
+		return -1;
+	}
+
+	/* Setup bind mounts for config files in /etc */
+	bind_etc(name);
+	return 0;
+}
+
+int netns_get_fd(const char *name)
+{
+	char pathbuf[PATH_MAX];
+	const char *path, *ptr;
+
+	path = name;
+	ptr = strchr(name, '/');
+	if (!ptr) {
+		snprintf(pathbuf, sizeof(pathbuf), "%s/%s",
+			NETNS_RUN_DIR, name );
+		path = pathbuf;
+	}
+	return open(path, O_RDONLY);
+}
+
+int netns_foreach(int (*func)(char *nsname, void *arg), void *arg)
+{
+	DIR *dir;
+	struct dirent *entry;
+
+	dir = opendir(NETNS_RUN_DIR);
+	if (!dir) {
+		if (errno == ENOENT)
+			return 0;
+
+		fprintf(stderr, "Failed to open directory %s: %s\n",
+			NETNS_RUN_DIR, strerror(errno));
+		return -1;
+	}
+
+	while ((entry = readdir(dir)) != NULL) {
+		if (strcmp(entry->d_name, ".") == 0)
+			continue;
+		if (strcmp(entry->d_name, "..") == 0)
+			continue;
+		if (func(entry->d_name, arg))
+			break;
+	}
+
+	closedir(dir);
+	return 0;
+}