1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
// +build linux
package netns
import (
"fmt"
"io/ioutil"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"syscall"
)
// SYS_SETNS syscall allows changing the namespace of the current process.
var SYS_SETNS = map[string]uintptr{
"386": 346,
"amd64": 308,
"arm64": 268,
"arm": 375,
"mips": 4344,
"mipsle": 4344,
"mips64le": 4344,
"ppc64": 350,
"ppc64le": 350,
"riscv64": 268,
"s390x": 339,
}[runtime.GOARCH]
// Deprecated: use syscall pkg instead (go >= 1.5 needed).
const (
CLONE_NEWUTS = 0x04000000 /* New utsname group? */
CLONE_NEWIPC = 0x08000000 /* New ipcs */
CLONE_NEWUSER = 0x10000000 /* New user namespace */
CLONE_NEWPID = 0x20000000 /* New pid namespace */
CLONE_NEWNET = 0x40000000 /* New network namespace */
CLONE_IO = 0x80000000 /* Get io context */
)
// Setns sets namespace using syscall. Note that this should be a method
// in syscall but it has not been added.
func Setns(ns NsHandle, nstype int) (err error) {
_, _, e1 := syscall.Syscall(SYS_SETNS, uintptr(ns), uintptr(nstype), 0)
if e1 != 0 {
err = e1
}
return
}
// Set sets the current network namespace to the namespace represented
// by NsHandle.
func Set(ns NsHandle) (err error) {
return Setns(ns, CLONE_NEWNET)
}
// New creates a new network namespace, sets it as current and returns
// a handle to it.
func New() (ns NsHandle, err error) {
if err := syscall.Unshare(CLONE_NEWNET); err != nil {
return -1, err
}
return Get()
}
// Get gets a handle to the current threads network namespace.
func Get() (NsHandle, error) {
return GetFromThread(os.Getpid(), syscall.Gettid())
}
// GetFromPath gets a handle to a network namespace
// identified by the path
func GetFromPath(path string) (NsHandle, error) {
fd, err := syscall.Open(path, syscall.O_RDONLY, 0)
if err != nil {
return -1, err
}
return NsHandle(fd), nil
}
// GetFromName gets a handle to a named network namespace such as one
// created by `ip netns add`.
func GetFromName(name string) (NsHandle, error) {
return GetFromPath(fmt.Sprintf("/var/run/netns/%s", name))
}
// GetFromPid gets a handle to the network namespace of a given pid.
func GetFromPid(pid int) (NsHandle, error) {
return GetFromPath(fmt.Sprintf("/proc/%d/ns/net", pid))
}
// GetFromThread gets a handle to the network namespace of a given pid and tid.
func GetFromThread(pid, tid int) (NsHandle, error) {
return GetFromPath(fmt.Sprintf("/proc/%d/task/%d/ns/net", pid, tid))
}
// GetFromDocker gets a handle to the network namespace of a docker container.
// Id is prefixed matched against the running docker containers, so a short
// identifier can be used as long as it isn't ambiguous.
func GetFromDocker(id string) (NsHandle, error) {
pid, err := getPidForContainer(id)
if err != nil {
return -1, err
}
return GetFromPid(pid)
}
// borrowed from docker/utils/utils.go
func findCgroupMountpoint(cgroupType string) (string, error) {
output, err := ioutil.ReadFile("/proc/mounts")
if err != nil {
return "", err
}
// /proc/mounts has 6 fields per line, one mount per line, e.g.
// cgroup /sys/fs/cgroup/devices cgroup rw,relatime,devices 0 0
for _, line := range strings.Split(string(output), "\n") {
parts := strings.Split(line, " ")
if len(parts) == 6 && parts[2] == "cgroup" {
for _, opt := range strings.Split(parts[3], ",") {
if opt == cgroupType {
return parts[1], nil
}
}
}
}
return "", fmt.Errorf("cgroup mountpoint not found for %s", cgroupType)
}
// Returns the relative path to the cgroup docker is running in.
// borrowed from docker/utils/utils.go
// modified to get the docker pid instead of using /proc/self
func getThisCgroup(cgroupType string) (string, error) {
dockerpid, err := ioutil.ReadFile("/var/run/docker.pid")
if err != nil {
return "", err
}
result := strings.Split(string(dockerpid), "\n")
if len(result) == 0 || len(result[0]) == 0 {
return "", fmt.Errorf("docker pid not found in /var/run/docker.pid")
}
pid, err := strconv.Atoi(result[0])
if err != nil {
return "", err
}
output, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/cgroup", pid))
if err != nil {
return "", err
}
for _, line := range strings.Split(string(output), "\n") {
parts := strings.Split(line, ":")
// any type used by docker should work
if parts[1] == cgroupType {
return parts[2], nil
}
}
return "", fmt.Errorf("cgroup '%s' not found in /proc/%d/cgroup", cgroupType, pid)
}
// Returns the first pid in a container.
// borrowed from docker/utils/utils.go
// modified to only return the first pid
// modified to glob with id
// modified to search for newer docker containers
func getPidForContainer(id string) (int, error) {
pid := 0
// memory is chosen randomly, any cgroup used by docker works
cgroupType := "memory"
cgroupRoot, err := findCgroupMountpoint(cgroupType)
if err != nil {
return pid, err
}
cgroupThis, err := getThisCgroup(cgroupType)
if err != nil {
return pid, err
}
id += "*"
attempts := []string{
filepath.Join(cgroupRoot, cgroupThis, id, "tasks"),
// With more recent lxc versions use, cgroup will be in lxc/
filepath.Join(cgroupRoot, cgroupThis, "lxc", id, "tasks"),
// With more recent docker, cgroup will be in docker/
filepath.Join(cgroupRoot, cgroupThis, "docker", id, "tasks"),
// Even more recent docker versions under systemd use docker-<id>.scope/
filepath.Join(cgroupRoot, "system.slice", "docker-"+id+".scope", "tasks"),
// Even more recent docker versions under cgroup/systemd/docker/<id>/
filepath.Join(cgroupRoot, "..", "systemd", "docker", id, "tasks"),
// Kubernetes with docker and CNI is even more different
filepath.Join(cgroupRoot, "..", "systemd", "kubepods", "*", "pod*", id, "tasks"),
// Another flavor of containers location in recent kubernetes 1.11+
filepath.Join(cgroupRoot, cgroupThis, "kubepods.slice", "kubepods-besteffort.slice", "*", "docker-"+id+".scope", "tasks"),
// When runs inside of a container with recent kubernetes 1.11+
filepath.Join(cgroupRoot, "kubepods.slice", "kubepods-besteffort.slice", "*", "docker-"+id+".scope", "tasks"),
}
var filename string
for _, attempt := range attempts {
filenames, _ := filepath.Glob(attempt)
if len(filenames) > 1 {
return pid, fmt.Errorf("Ambiguous id supplied: %v", filenames)
} else if len(filenames) == 1 {
filename = filenames[0]
break
}
}
if filename == "" {
return pid, fmt.Errorf("Unable to find container: %v", id[:len(id)-1])
}
output, err := ioutil.ReadFile(filename)
if err != nil {
return pid, err
}
result := strings.Split(string(output), "\n")
if len(result) == 0 || len(result[0]) == 0 {
return pid, fmt.Errorf("No pid found for container")
}
pid, err = strconv.Atoi(result[0])
if err != nil {
return pid, fmt.Errorf("Invalid pid '%s': %s", result[0], err)
}
return pid, nil
}
|
