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Date: Sat, 13 Dec 2014 09:29:36 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Vadim Kochan <vadim4j@...il.com>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH iproute2 v4] ip: Simplify executing ip cmd within network
ns
Fri, Dec 12, 2014 at 11:15:07PM CET, vadim4j@...il.com wrote:
>From: Vadim Kochan <vadim4j@...il.com>
>
>Added new '-netns' option to simplify executing following cmd:
>
> ip netns exec NETNS ip OPTIONS COMMAND OBJECT
>
> to
>
> ip -n[etns] NETNS OPTIONS COMMAND OBJECT
>
>e.g.:
>
> ip -net vnet0 link add br0 type bridge
> ip -n vnet0 link
>
>Signed-off-by: Vadim Kochan <vadim4j@...il.com>
This looks good. I'm still missing support in tc, bridge, etc. I think
it would be great to do this in the same patch/patchset.
>---
> include/namespace.h | 46 +++++++++++++++++++++++
> ip/ip.c | 5 +++
> ip/ipnetns.c | 106 ++--------------------------------------------------
> lib/Makefile | 6 ++-
> lib/namespace.c | 86 ++++++++++++++++++++++++++++++++++++++++++
> man/man8/ip.8 | 23 +++++++++++-
> 6 files changed, 167 insertions(+), 105 deletions(-)
> create mode 100644 include/namespace.h
> create mode 100644 lib/namespace.c
>
>diff --git a/include/namespace.h b/include/namespace.h
>new file mode 100644
>index 0000000..2f13e65
>--- /dev/null
>+++ b/include/namespace.h
>@@ -0,0 +1,46 @@
>+#ifndef __NAMESPACE_H__
>+#define __NAMESPACE_H__ 1
>+
>+#include <sched.h>
>+#include <sys/mount.h>
>+#include <errno.h>
>+
>+#define NETNS_RUN_DIR "/var/run/netns"
>+#define NETNS_ETC_DIR "/etc/netns"
>+
>+#ifndef CLONE_NEWNET
>+#define CLONE_NEWNET 0x40000000 /* New network namespace (lo, device, names sockets, etc) */
>+#endif
>+
>+#ifndef MNT_DETACH
>+#define MNT_DETACH 0x00000002 /* Just detach from the tree */
>+#endif /* MNT_DETACH */
>+
>+/* sys/mount.h may be out too old to have these */
>+#ifndef MS_REC
>+#define MS_REC 16384
>+#endif
>+
>+#ifndef MS_SLAVE
>+#define MS_SLAVE (1 << 19)
>+#endif
>+
>+#ifndef MS_SHARED
>+#define MS_SHARED (1 << 20)
>+#endif
>+
>+#ifndef HAVE_SETNS
>+static int setns(int fd, int nstype)
>+{
>+#ifdef __NR_setns
>+ return syscall(__NR_setns, fd, nstype);
>+#else
>+ errno = ENOSYS;
>+ return -1;
>+#endif
>+}
>+#endif /* HAVE_SETNS */
>+
>+extern int netns_switch(char *netns);
>+
>+#endif /* __NAMESPACE_H__ */
>diff --git a/ip/ip.c b/ip/ip.c
>index 5f759d5..d6c9123 100644
>--- a/ip/ip.c
>+++ b/ip/ip.c
>@@ -22,6 +22,7 @@
> #include "SNAPSHOT.h"
> #include "utils.h"
> #include "ip_common.h"
>+#include "namespace.h"
>
> int preferred_family = AF_UNSPEC;
> int human_readable = 0;
>@@ -262,6 +263,10 @@ int main(int argc, char **argv)
> rcvbuf = size;
> } else if (matches(opt, "-help") == 0) {
> usage();
>+ } else if (matches(opt, "-netns") == 0) {
>+ NEXT_ARG();
>+ if (netns_switch(argv[1]))
>+ exit(-1);
> } else {
> fprintf(stderr, "Option \"%s\" is unknown, try \"ip -help\".\n", opt);
> exit(-1);
>diff --git a/ip/ipnetns.c b/ip/ipnetns.c
>index 1c8aa02..519d518 100644
>--- a/ip/ipnetns.c
>+++ b/ip/ipnetns.c
>@@ -17,42 +17,7 @@
>
> #include "utils.h"
> #include "ip_common.h"
>-
>-#define NETNS_RUN_DIR "/var/run/netns"
>-#define NETNS_ETC_DIR "/etc/netns"
>-
>-#ifndef CLONE_NEWNET
>-#define CLONE_NEWNET 0x40000000 /* New network namespace (lo, device, names sockets, etc) */
>-#endif
>-
>-#ifndef MNT_DETACH
>-#define MNT_DETACH 0x00000002 /* Just detach from the tree */
>-#endif /* MNT_DETACH */
>-
>-/* sys/mount.h may be out too old to have these */
>-#ifndef MS_REC
>-#define MS_REC 16384
>-#endif
>-
>-#ifndef MS_SLAVE
>-#define MS_SLAVE (1 << 19)
>-#endif
>-
>-#ifndef MS_SHARED
>-#define MS_SHARED (1 << 20)
>-#endif
>-
>-#ifndef HAVE_SETNS
>-static int setns(int fd, int nstype)
>-{
>-#ifdef __NR_setns
>- return syscall(__NR_setns, fd, nstype);
>-#else
>- errno = ENOSYS;
>- return -1;
>-#endif
>-}
>-#endif /* HAVE_SETNS */
>+#include "namespace.h"
>
> static int usage(void)
> {
>@@ -101,42 +66,12 @@ static int netns_list(int argc, char **argv)
> return 0;
> }
>
>-static void bind_etc(const char *name)
>-{
>- char etc_netns_path[MAXPATHLEN];
>- char netns_name[MAXPATHLEN];
>- char etc_name[MAXPATHLEN];
>- struct dirent *entry;
>- DIR *dir;
>-
>- 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);
>-}
>-
> static int netns_exec(int argc, char **argv)
> {
> /* Setup the proper environment for apps that are not netns
> * aware, and execute a program in that environment.
> */
>- const char *name, *cmd;
>- char net_path[MAXPATHLEN];
>- int netns;
>+ const char *cmd;
>
> if (argc < 1) {
> fprintf(stderr, "No netns name specified\n");
>@@ -146,45 +81,10 @@ static int netns_exec(int argc, char **argv)
> fprintf(stderr, "No command specified\n");
> return -1;
> }
>-
>- name = argv[0];
> cmd = argv[1];
>- 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));
>- return -1;
>- }
>
>- 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));
>+ if (netns_switch(argv[0]))
> return -1;
>- }
>- /* Mount a version of /sys that describes the network namespace */
>- if (umount2("/sys", MNT_DETACH) < 0) {
>- fprintf(stderr, "umount of /sys failed: %s\n", strerror(errno));
>- return -1;
>- }
>- if (mount(name, "/sys", "sysfs", 0, 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);
>
> fflush(stdout);
>
>diff --git a/lib/Makefile b/lib/Makefile
>index a42b885..66f89f1 100644
>--- a/lib/Makefile
>+++ b/lib/Makefile
>@@ -1,8 +1,12 @@
> include ../Config
>
>+ifeq ($(IP_CONFIG_SETNS),y)
>+ CFLAGS += -DHAVE_SETNS
>+endif
>+
> CFLAGS += -fPIC
>
>-UTILOBJ=utils.o rt_names.o ll_types.o ll_proto.o ll_addr.o inet_proto.o
>+UTILOBJ=utils.o rt_names.o ll_types.o ll_proto.o ll_addr.o inet_proto.o namespace.o
>
> NLOBJ=libgenl.o ll_map.o libnetlink.o
>
>diff --git a/lib/namespace.c b/lib/namespace.c
>new file mode 100644
>index 0000000..1554ce0
>--- /dev/null
>+++ b/lib/namespace.c
>@@ -0,0 +1,86 @@
>+/*
>+ * 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 <fcntl.h>
>+#include <dirent.h>
>+
>+#include "utils.h"
>+#include "namespace.h"
>+
>+static void bind_etc(const char *name)
>+{
>+ char etc_netns_path[MAXPATHLEN];
>+ char netns_name[MAXPATHLEN];
>+ char etc_name[MAXPATHLEN];
>+ struct dirent *entry;
>+ DIR *dir;
>+
>+ 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[MAXPATHLEN];
>+ int netns;
>+
>+ 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));
>+ return -1;
>+ }
>+
>+ 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) {
>+ fprintf(stderr, "umount of /sys failed: %s\n", strerror(errno));
>+ return -1;
>+ }
>+ if (mount(name, "/sys", "sysfs", 0, 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;
>+}
>diff --git a/man/man8/ip.8 b/man/man8/ip.8
>index 2d42e98..0fb759d 100644
>--- a/man/man8/ip.8
>+++ b/man/man8/ip.8
>@@ -31,7 +31,8 @@ ip \- show / manipulate routing, devices, policy routing and tunnels
> \fB\-r\fR[\fIesolve\fR] |
> \fB\-f\fR[\fIamily\fR] {
> .BR inet " | " inet6 " | " ipx " | " dnet " | " link " } | "
>-\fB\-o\fR[\fIneline\fR] }
>+\fB\-o\fR[\fIneline\fR] |
>+\fB\-n\fR[\fIetns\fR] }
>
>
> .SH OPTIONS
>@@ -134,6 +135,26 @@ the output.
> use the system's name resolver to print DNS names instead of
> host addresses.
>
>+.TP
>+.BR "\-n" , " \-net" , " \-netns " <NETNS>
>+switches
>+.B ip
>+to the specified network namespace
>+.IR NETNS .
>+Actually it just simplifies executing of:
>+
>+.B ip netns exec
>+.IR NETNS
>+.B ip
>+.RI "[ " OPTIONS " ] " OBJECT " { " COMMAND " | "
>+.BR help " }"
>+
>+to
>+
>+.B ip
>+.RI "-n[etns] " NETNS " [ " OPTIONS " ] " OBJECT " { " COMMAND " | "
>+.BR help " }"
>+
> .SH IP - COMMAND SYNTAX
>
> .SS
>--
>2.1.3
>
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