aboutsummaryrefslogtreecommitdiff
path: root/pkg/apparmor/apparmor_linux.go
blob: 2c5022c1fb1e5a99531ced5d934f68768673b557 (plain)
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
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
// +build linux,apparmor

package apparmor

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"os/exec"
	"path"
	"strconv"
	"strings"
	"text/template"

	"github.com/containers/libpod/pkg/rootless"
	runcaa "github.com/opencontainers/runc/libcontainer/apparmor"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
)

// profileDirectory is the file store for apparmor profiles and macros.
var profileDirectory = "/etc/apparmor.d"

// IsEnabled returns true if AppArmor is enabled on the host.
func IsEnabled() bool {
	if rootless.IsRootless() {
		return false
	}
	return runcaa.IsEnabled()
}

// profileData holds information about the given profile for generation.
type profileData struct {
	// Name is profile name.
	Name string
	// Imports defines the apparmor functions to import, before defining the profile.
	Imports []string
	// InnerImports defines the apparmor functions to import in the profile.
	InnerImports []string
	// Version is the {major, minor, patch} version of apparmor_parser as a single number.
	Version int
}

// generateDefault creates an apparmor profile from ProfileData.
func (p *profileData) generateDefault(out io.Writer) error {
	compiled, err := template.New("apparmor_profile").Parse(libpodProfileTemplate)
	if err != nil {
		return err
	}

	if macroExists("tunables/global") {
		p.Imports = append(p.Imports, "#include <tunables/global>")
	} else {
		p.Imports = append(p.Imports, "@{PROC}=/proc/")
	}

	if macroExists("abstractions/base") {
		p.InnerImports = append(p.InnerImports, "#include <abstractions/base>")
	}

	ver, err := getAAParserVersion()
	if err != nil {
		return err
	}
	p.Version = ver

	return compiled.Execute(out, p)
}

// macrosExists checks if the passed macro exists.
func macroExists(m string) bool {
	_, err := os.Stat(path.Join(profileDirectory, m))
	return err == nil
}

// InstallDefault generates a default profile and loads it into the kernel
// using 'apparmor_parser'.
func InstallDefault(name string) error {
	if rootless.IsRootless() {
		return ErrApparmorRootless
	}

	p := profileData{
		Name: name,
	}

	cmd := exec.Command("apparmor_parser", "-Kr")
	pipe, err := cmd.StdinPipe()
	if err != nil {
		return err
	}
	if err := cmd.Start(); err != nil {
		pipe.Close()
		return err
	}
	if err := p.generateDefault(pipe); err != nil {
		pipe.Close()
		cmd.Wait()
		return err
	}

	pipe.Close()
	return cmd.Wait()
}

// IsLoaded checks if a profile with the given name has been loaded into the
// kernel.
func IsLoaded(name string) (bool, error) {
	if name != "" && rootless.IsRootless() {
		return false, errors.Wrapf(ErrApparmorRootless, "cannot load AppArmor profile %q", name)
	}

	file, err := os.Open("/sys/kernel/security/apparmor/profiles")
	if err != nil {
		if os.IsNotExist(err) {
			return false, nil
		}
		return false, err
	}
	defer file.Close()

	r := bufio.NewReader(file)
	for {
		p, err := r.ReadString('\n')
		if err == io.EOF {
			break
		}
		if err != nil {
			return false, err
		}
		if strings.HasPrefix(p, name+" ") {
			return true, nil
		}
	}

	return false, nil
}

// execAAParser runs `apparmor_parser` with the passed arguments.
func execAAParser(dir string, args ...string) (string, error) {
	c := exec.Command("apparmor_parser", args...)
	c.Dir = dir

	output, err := c.CombinedOutput()
	if err != nil {
		return "", fmt.Errorf("running `%s %s` failed with output: %s\nerror: %v", c.Path, strings.Join(c.Args, " "), output, err)
	}

	return string(output), nil
}

// getAAParserVersion returns the major and minor version of apparmor_parser.
func getAAParserVersion() (int, error) {
	output, err := execAAParser("", "--version")
	if err != nil {
		return -1, err
	}
	return parseAAParserVersion(output)
}

// parseAAParserVersion parses the given `apparmor_parser --version` output and
// returns the major and minor version number as an integer.
func parseAAParserVersion(output string) (int, error) {
	// output is in the form of the following:
	// AppArmor parser version 2.9.1
	// Copyright (C) 1999-2008 Novell Inc.
	// Copyright 2009-2012 Canonical Ltd.
	lines := strings.SplitN(output, "\n", 2)
	words := strings.Split(lines[0], " ")
	version := words[len(words)-1]

	// split by major minor version
	v := strings.Split(version, ".")
	if len(v) == 0 || len(v) > 3 {
		return -1, fmt.Errorf("parsing version failed for output: `%s`", output)
	}

	// Default the versions to 0.
	var majorVersion, minorVersion, patchLevel int

	majorVersion, err := strconv.Atoi(v[0])
	if err != nil {
		return -1, err
	}

	if len(v) > 1 {
		minorVersion, err = strconv.Atoi(v[1])
		if err != nil {
			return -1, err
		}
	}
	if len(v) > 2 {
		patchLevel, err = strconv.Atoi(v[2])
		if err != nil {
			return -1, err
		}
	}

	// major*10^5 + minor*10^3 + patch*10^0
	numericVersion := majorVersion*1e5 + minorVersion*1e3 + patchLevel
	return numericVersion, nil

}

// CheckProfileAndLoadDefault checks if the specified profile is loaded and
// loads the DefaultLibpodProfile if the specified on is prefixed by
// DefaultLipodProfilePrefix.  This allows to always load and apply the latest
// default AppArmor profile.  Note that AppArmor requires root.  If it's a
// default profile, return DefaultLipodProfilePrefix, otherwise the specified
// one.
func CheckProfileAndLoadDefault(name string) (string, error) {
	if name == "unconfined" {
		return name, nil
	}

	// AppArmor is not supported in rootless mode as it requires root
	// privileges.  Return an error in case a specific profile is specified.
	if rootless.IsRootless() {
		if name != "" {
			return "", errors.Wrapf(ErrApparmorRootless, "cannot load AppArmor profile %q", name)
		} else {
			logrus.Debug("skipping loading default AppArmor profile (rootless mode)")
			return "", nil
		}
	}

	if name != "" && !runcaa.IsEnabled() {
		return "", fmt.Errorf("profile %q specified but AppArmor is disabled on the host", name)
	}

	// If the specified name is not empty or is not a default libpod one,
	// ignore it and return the name.
	if name != "" && !strings.HasPrefix(name, DefaultLipodProfilePrefix) {
		isLoaded, err := IsLoaded(name)
		if err != nil {
			return "", err
		}
		if !isLoaded {
			return "", fmt.Errorf("AppArmor profile %q specified but not loaded", name)
		}
		return name, nil
	}

	name = DefaultLibpodProfile
	// To avoid expensive redundant loads on each invocation, check
	// if it's loaded before installing it.
	isLoaded, err := IsLoaded(name)
	if err != nil {
		return "", err
	}
	if !isLoaded {
		err = InstallDefault(name)
		if err != nil {
			return "", err
		}
		logrus.Infof("successfully loaded AppAmor profile %q", name)
	} else {
		logrus.Infof("AppAmor profile %q is already loaded", name)
	}

	return name, nil
}