-
Notifications
You must be signed in to change notification settings - Fork 187
/
capabilities.go
209 lines (185 loc) · 4.89 KB
/
capabilities.go
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
package capabilities
// Copyright 2013-2018 Docker, Inc.
// NOTE: this package has been copied from github.com/docker/docker but been
// changed significantly to fit the needs of libpod.
import (
"sort"
"strings"
"sync"
"github.com/pkg/errors"
"github.com/syndtr/gocapability/capability"
)
var (
// Used internally and populated during init().
capabilityList []string
// Used internally and populated during init().
capsList []capability.Cap
// ErrUnknownCapability is thrown when an unknown capability is processed.
ErrUnknownCapability = errors.New("unknown capability")
// ContainerImageLabels - label can indicate the required
// capabilities required by containers to run the container image.
ContainerImageLabels = []string{"io.containers.capabilities"}
)
// All is a special value used to add/drop all known capabilities.
// Useful on the CLI for `--cap-add=all` etc.
const All = "ALL"
func getCapName(c capability.Cap) string {
return "CAP_" + strings.ToUpper(c.String())
}
func init() {
last := capability.CAP_LAST_CAP
// hack for RHEL6 which has no /proc/sys/kernel/cap_last_cap
if last == capability.Cap(63) {
last = capability.CAP_BLOCK_SUSPEND
}
for _, cap := range capability.List() {
if cap > last {
continue
}
capsList = append(capsList, cap)
capabilityList = append(capabilityList, getCapName(cap))
sort.Strings(capabilityList)
}
}
// stringInSlice determines if a string is in a string slice, returns bool
func stringInSlice(s string, sl []string) bool {
for _, i := range sl {
if i == s {
return true
}
}
return false
}
var (
boundingSetOnce sync.Once
boundingSetRet []string
boundingSetErr error
)
// BoundingSet returns the capabilities in the current bounding set
func BoundingSet() ([]string, error) {
boundingSetOnce.Do(func() {
currentCaps, err := capability.NewPid2(0)
if err != nil {
boundingSetErr = err
return
}
err = currentCaps.Load()
if err != nil {
boundingSetErr = err
return
}
var r []string
for _, c := range capsList {
if !currentCaps.Get(capability.BOUNDING, c) {
continue
}
r = append(r, getCapName(c))
}
boundingSetRet = r
sort.Strings(boundingSetRet)
boundingSetErr = err
})
return boundingSetRet, boundingSetErr
}
// AllCapabilities returns all known capabilities.
func AllCapabilities() []string {
return capabilityList
}
// NormalizeCapabilities normalizes caps by adding a "CAP_" prefix (if not yet
// present).
func NormalizeCapabilities(caps []string) ([]string, error) {
normalized := make([]string, len(caps))
for i, c := range caps {
c = strings.ToUpper(c)
if c == All {
normalized = append(normalized, c)
continue
}
if !strings.HasPrefix(c, "CAP_") {
c = "CAP_" + c
}
if !stringInSlice(c, capabilityList) {
return nil, errors.Wrapf(ErrUnknownCapability, "%q", c)
}
normalized[i] = c
}
sort.Strings(normalized)
return normalized, nil
}
// ValidateCapabilities validates if caps only contains valid capabilities.
func ValidateCapabilities(caps []string) error {
for _, c := range caps {
if !stringInSlice(c, capabilityList) {
return errors.Wrapf(ErrUnknownCapability, "%q", c)
}
}
return nil
}
// MergeCapabilities computes a set of capabilities by adding capabilities
// to or dropping them from base.
//
// Note that:
// "ALL" in capAdd adds returns known capabilities
// "All" in capDrop returns only the capabilities specified in capAdd
func MergeCapabilities(base, adds, drops []string) ([]string, error) {
var caps []string
// Normalize the base capabilities
base, err := NormalizeCapabilities(base)
if err != nil {
return nil, err
}
if len(adds) == 0 && len(drops) == 0 {
// Nothing to tweak; we're done
return base, nil
}
capDrop, err := NormalizeCapabilities(drops)
if err != nil {
return nil, err
}
capAdd, err := NormalizeCapabilities(adds)
if err != nil {
return nil, err
}
if stringInSlice(All, capDrop) {
if stringInSlice(All, capAdd) {
return nil, errors.New("adding all caps and removing all caps not allowed")
}
// "Drop" all capabilities; return what's in capAdd instead
sort.Strings(capAdd)
return capAdd, nil
}
if stringInSlice(All, capAdd) {
base, err = BoundingSet()
if err != nil {
return nil, err
}
capAdd = []string{}
} else {
for _, add := range capAdd {
if stringInSlice(add, capDrop) {
return nil, errors.Errorf("capability %q cannot be dropped and added", add)
}
}
}
for _, drop := range capDrop {
if stringInSlice(drop, capAdd) {
return nil, errors.Errorf("capability %q cannot be dropped and added", drop)
}
}
// Drop any capabilities in capDrop that are in base
for _, cap := range base {
if stringInSlice(cap, capDrop) {
continue
}
caps = append(caps, cap)
}
// Add any capabilities in capAdd that are not in base
for _, cap := range capAdd {
if stringInSlice(cap, base) {
continue
}
caps = append(caps, cap)
}
sort.Strings(caps)
return caps, nil
}