ns: Introduce ns descriptors

These are structs that (now) tie together ns string
and the CLONE_ flag. It's nice to have one (some code
becomes simpler) and will help us with auto-namespaces
detection.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/ipc_ns.h

@@ -8,7 +8,9 @@ extern void show_ipc_var(int fd, struct cr_options *);
 extern void show_ipc_shm(int fd, struct cr_options *);
 extern void show_ipc_msg(int fd, struct cr_options *);
 extern void show_ipc_sem(int fd, struct cr_options *);
-extern int dump_ipc_ns(int ns_pid, struct cr_fdset *fdset);
+extern int dump_ipc_ns(int ns_pid, const struct cr_fdset *fdset);
 extern int prepare_ipc_ns(int pid);
 
+extern struct ns_desc ipc_ns_desc;
+
 #endif /* __CR_IPC_NS_H__ */

include/mount.h

@@ -22,4 +22,6 @@ struct mount_info;
 extern struct mount_info *lookup_mnt_id(unsigned int id);
 extern struct mount_info *lookup_mnt_sdev(unsigned int s_dev);
 
+extern struct ns_desc mnt_ns_desc;
+
 #endif /* __CR_MOUNT_H__ */

include/namespaces.h

@@ -8,7 +8,14 @@ int dump_namespaces(struct pid *pid, unsigned int ns_flags);
 int prepare_namespace(int pid, unsigned long clone_flags);
 struct cr_options;
 int try_show_namespaces(int pid, struct cr_options *);
-int switch_ns(int pid, int type, char *ns, int *rst);
-int restore_ns(int rst, int type);
+
+struct ns_desc {
+	unsigned int cflag;
+	char *str;
+};
+
+int switch_ns(int pid, struct ns_desc *nd, int *rst);
+int restore_ns(int rst, struct ns_desc *nd);
+extern struct ns_desc pid_ns_desc;
 
 #endif /* __CR_NS_H__ */

include/net.h

@@ -20,4 +20,6 @@ struct veth_pair {
 extern int network_lock(void);
 extern void network_unlock(void);
 
+extern struct ns_desc net_ns_desc;
+
 #endif /* __CR_NET_H__ */

include/uts_ns.h

@@ -8,4 +8,6 @@ struct cr_options;
 void show_utsns(int fd, struct cr_options *);
 int prepare_utsns(int pid);
 
+extern struct ns_desc uts_ns_desc;
+
 #endif /* __CR_UTS_NS_H__ */

ipc_ns.c

@@ -12,6 +12,7 @@
 #include "syscall.h"
 #include "namespaces.h"
 #include "sysctl.h"
+#include "ipc_ns.h"
 
 #include "protobuf.h"
 #include "protobuf/ipc-var.pb-c.h"
@@ -436,7 +437,7 @@ int dump_ipc_ns(int ns_pid, const struct cr_fdset *fdset)
 {
 	int ret;
 
-	ret = switch_ns(ns_pid, CLONE_NEWIPC, "ipc", NULL);
+	ret = switch_ns(ns_pid, &ipc_ns_desc, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -873,3 +874,8 @@ int prepare_ipc_ns(int pid)
 		return ret;
 	return 0;
 }
+
+struct ns_desc ipc_ns_desc = {
+	.cflag = CLONE_NEWIPC,
+	.str = "ipc",
+};

mount.c

@@ -19,7 +19,7 @@
 #include "mount.h"
 #include "proc_parse.h"
 #include "image.h"
-
+#include "namespaces.h"
 #include "protobuf.h"
 #include "protobuf/mnt.pb-c.h"
 
@@ -763,3 +763,8 @@ int mntns_collect_root(pid_t pid)
 
 	return 0;
 }
+
+struct ns_desc mnt_ns_desc = {
+	.cflag = CLONE_NEWNS,
+	.str = "mnt",
+};

namespaces.c

@@ -10,13 +10,13 @@
 #include "namespaces.h"
 #include "net.h"
 
-int switch_ns(int pid, int type, char *ns, int *rst)
+int switch_ns(int pid, struct ns_desc *nd, int *rst)
 {
 	char buf[32];
 	int nsfd;
 	int ret = -1;
 
-	snprintf(buf, sizeof(buf), "/proc/%d/ns/%s", pid, ns);
+	snprintf(buf, sizeof(buf), "/proc/%d/ns/%s", pid, nd->str);
 	nsfd = open(buf, O_RDONLY);
 	if (nsfd < 0) {
 		pr_perror("Can't open ipcns file");
@@ -24,7 +24,7 @@ int switch_ns(int pid, int type, char *ns, int *rst)
 	}
 
 	if (rst) {
-		snprintf(buf, sizeof(buf), "/proc/self/ns/%s", ns);
+		snprintf(buf, sizeof(buf), "/proc/self/ns/%s", nd->str);
 		*rst = open(buf, O_RDONLY);
 		if (*rst < 0) {
 			pr_perror("Can't open ns file");
@@ -32,9 +32,9 @@ int switch_ns(int pid, int type, char *ns, int *rst)
 		}
 	}
 
-	ret = setns(nsfd, type);
+	ret = setns(nsfd, nd->cflag);
 	if (ret < 0) {
-		pr_perror("Can't setns %d/%s", pid, ns);
+		pr_perror("Can't setns %d/%s", pid, nd->str);
 		goto err_set;
 	}
 
@@ -50,11 +50,11 @@ err_ns:
 	return -1;
 }
 
-int restore_ns(int rst, int type)
+int restore_ns(int rst, struct ns_desc *nd)
 {
 	int ret;
 
-	ret = setns(rst, type);
+	ret = setns(rst, nd->cflag);
 	if (ret < 0)
 		pr_perror("Can't restore ns back");
 
@@ -197,3 +197,8 @@ int try_show_namespaces(int ns_pid, struct cr_options *o)
 	close_cr_fdset(&fdset);
 	return 0;
 }
+
+struct ns_desc pid_ns_desc = {
+	.cflag = CLONE_NEWPID,
+	.str = "pid",
+};

net.c

@@ -339,7 +339,7 @@ int dump_net_ns(int pid, struct cr_fdset *fds)
 {
 	int ret;
 
-	ret = switch_ns(pid, CLONE_NEWNET, "net", NULL);
+	ret = switch_ns(pid, &net_ns_desc, NULL);
 	if (!ret)
 		ret = dump_links(fds);
 	if (!ret)
@@ -402,3 +402,7 @@ void network_unlock(void)
 	run_scripts("network-unlock");
 }
 
+struct ns_desc net_ns_desc = {
+	.cflag = CLONE_NEWNET,
+	.str = "net",
+};

parasite-syscall.c

@@ -20,6 +20,7 @@
 #include "crtools.h"
 #include "namespaces.h"
 #include "pstree.h"
+#include "net.h"
 
 #include <string.h>
 #include <stdlib.h>
@@ -300,7 +301,7 @@ static int parasite_init(struct parasite_ctl *ctl, pid_t pid, int nr_threads)
 		if (opts.namespaces_flags & CLONE_NEWNET) {
 			pr_info("Switching to %d's net for tsock creation\n", pid);
 
-			if (switch_ns(pid, CLONE_NEWNET, "net", &rst))
+			if (switch_ns(pid, &net_ns_desc, &rst))
 				return -1;
 		}
 
@@ -315,7 +316,7 @@ static int parasite_init(struct parasite_ctl *ctl, pid_t pid, int nr_threads)
 			goto err;
 		}
 
-		if (rst > 0 && restore_ns(rst, CLONE_NEWNET) < 0)
+		if (rst > 0 && restore_ns(rst, &net_ns_desc) < 0)
 			goto err;
 	} else {
 		struct sockaddr addr = { .sa_family = AF_UNSPEC, };

sockets.c

@@ -428,7 +428,7 @@ int collect_sockets(int pid)
 	if (opts.namespaces_flags & CLONE_NEWNET) {
 		pr_info("Switching to %d's net for collecting sockets\n", pid);
 
-		if (switch_ns(pid, CLONE_NEWNET, "net", &rst))
+		if (switch_ns(pid, &net_ns_desc, &rst))
 			return -1;
 	}
 
@@ -521,7 +521,7 @@ int collect_sockets(int pid)
 
 	close(nl);
 out:
-	if (rst > 0 && restore_ns(rst, CLONE_NEWNET) < 0)
+	if (rst > 0 && restore_ns(rst, &net_ns_desc) < 0)
 		err = -1;
 	return err;
 }

uts_ns.c

@@ -8,6 +8,7 @@
 #include "syscall.h"
 #include "namespaces.h"
 #include "sysctl.h"
+#include "uts_ns.h"
 
 #include "protobuf.h"
 #include "protobuf/utsns.pb-c.h"
@@ -18,7 +19,7 @@ int dump_uts_ns(int ns_pid, struct cr_fdset *fdset)
 	struct utsname ubuf;
 	UtsnsEntry ue = UTSNS_ENTRY__INIT;
 
-	ret = switch_ns(ns_pid, CLONE_NEWUTS, "uts", NULL);
+	ret = switch_ns(ns_pid, &uts_ns_desc, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -68,3 +69,8 @@ void show_utsns(int fd, struct cr_options *o)
 {
 	pb_show_vertical(fd, PB_UTSNS);
 }
+
+struct ns_desc uts_ns_desc = {
+	.cflag = CLONE_NEWUTS,
+	.str = "uts",
+};