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
|
// Copyright 2018 Google Inc. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"debug/elf"
"fmt"
"testing"
)
// prog is a shortcut to fill out a elf.Prog structure
func prog(flags elf.ProgFlag, offset, addr, filesz, memsz uint64) *elf.Prog {
return &elf.Prog{
ProgHeader: elf.ProgHeader{
Type: elf.PT_LOAD,
Flags: flags,
Off: offset,
Vaddr: addr,
Paddr: addr,
Filesz: filesz,
Memsz: memsz,
},
}
}
// linkerGold returns an example elf.File from a linker binary that was linked
// with gold.
func linkerGold() *elf.File {
return &elf.File{
Progs: []*elf.Prog{
prog(elf.PF_R|elf.PF_X, 0, 0, 0xd0fac, 0xd0fac),
prog(elf.PF_R|elf.PF_W, 0xd1050, 0xd2050, 0x6890, 0xd88c),
},
}
}
// fileGold returns an example elf binary with a properly embedded linker. The
// embedded linker was the one returned by linkerGold.
func fileGold() *elf.File {
return &elf.File{
Progs: []*elf.Prog{
prog(elf.PF_R, 0, 0, 0x2e0, 0x2e0),
prog(elf.PF_R|elf.PF_X, 0x1000, 0x1000, 0xd0fac, 0xd0fac),
prog(elf.PF_R|elf.PF_W, 0xd2050, 0xd3050, 0xd88c, 0xd88c),
prog(elf.PF_R, 0xe0000, 0xe1000, 0x10e4, 0x10e4),
prog(elf.PF_R|elf.PF_X, 0xe2000, 0xe3000, 0x1360, 0x1360),
prog(elf.PF_R|elf.PF_W, 0xe4000, 0xe5000, 0x1358, 0x1358),
},
}
}
// linkerLld returns an example elf.File from a linker binary that was linked
// with lld.
func linkerLld() *elf.File {
return &elf.File{
Progs: []*elf.Prog{
prog(elf.PF_R, 0, 0, 0x3c944, 0x3c944),
prog(elf.PF_R|elf.PF_X, 0x3d000, 0x3d000, 0x946fa, 0x946fa),
prog(elf.PF_R|elf.PF_W, 0xd2000, 0xd2000, 0x7450, 0xf778),
},
}
}
// fileGold returns an example elf binary with a properly embedded linker. The
// embedded linker was the one returned by linkerLld.
func fileLld() *elf.File {
return &elf.File{
Progs: []*elf.Prog{
prog(elf.PF_R, 0, 0, 0x3d944, 0x3d944),
prog(elf.PF_R|elf.PF_X, 0x3e000, 0x3e000, 0x946fa, 0x946fa),
prog(elf.PF_R|elf.PF_W, 0xd3000, 0xd3000, 0xf778, 0xf778),
prog(elf.PF_R, 0xe3000, 0xe3000, 0x10e4, 0x10e4),
prog(elf.PF_R|elf.PF_X, 0xe5000, 0xe5000, 0x1360, 0x1360),
prog(elf.PF_R|elf.PF_W, 0xe7000, 0xe7000, 0x1358, 0x1358),
},
}
}
// linkerOffset returns the symbol representing the linker offset used by both
// fileGold and fileLld
func linkerOffset() []elf.Symbol {
return []elf.Symbol{
elf.Symbol{
Name: "__dlwrap_linker_offset",
Value: 0x1000,
},
}
}
func TestCheckLinker(t *testing.T) {
cases := []struct {
name string
err error
file func() *elf.File
linker func() *elf.File
}{
{
name: "good gold-linked linker",
file: fileGold,
linker: linkerGold,
},
{
name: "good lld-linked linker",
file: fileLld,
linker: linkerLld,
},
{
name: "truncated RO section",
err: fmt.Errorf("Linker prog 0 (0x0) not fully present (0x3d944 > 0x3d943)"),
file: func() *elf.File {
f := fileLld()
f.Progs[0].Filesz -= 1
f.Progs[0].Memsz -= 1
return f
},
linker: linkerLld,
},
}
for _, tc := range cases {
t.Run(tc.name, func(t *testing.T) {
err := checkLinker(tc.file(), tc.linker(), linkerOffset())
if tc.err == nil {
if err != nil {
t.Fatalf("No error expected, but got: %v", err)
}
} else if err == nil {
t.Fatalf("Returned no error, but wanted: %v", tc.err)
} else if err.Error() != tc.err.Error() {
t.Fatalf("Different error found:\nwant: %v\n got: %v", tc.err, err)
}
})
}
}
|
