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
|
// Copyright 2015 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
// This file does serialization of programs for executor binary.
// The format aims at simple parsing: binary and irreversible.
package prog
import (
"fmt"
)
const (
ExecInstrEOF = ^uintptr(iota)
ExecInstrCopyin
ExecInstrCopyout
)
const (
ExecArgConst = uintptr(iota)
ExecArgResult
ExecArgData
)
const (
ptrSize = 8
pageSize = 4 << 10
dataOffset = 512 << 20
)
func (p *Prog) SerializeForExec() []byte {
if err := p.validate(); err != nil {
panic(fmt.Errorf("serializing invalid program: %v", err))
}
var instrSeq uintptr
w := &execContext{args: make(map[*Arg]*argInfo)}
for _, c := range p.Calls {
// Calculate arg offsets within structs.
foreachArg(c, func(arg, base *Arg, _ *[]*Arg) {
if base == nil || arg.Kind == ArgGroup {
return
}
if w.args[base] == nil {
w.args[base] = &argInfo{}
}
w.args[arg] = &argInfo{Offset: w.args[base].CurSize}
w.args[base].CurSize += arg.Size(arg.Type)
})
// Generate copyin instructions that fill in data into pointer arguments.
foreachArg(c, func(arg, _ *Arg, _ *[]*Arg) {
if arg.Kind == ArgPointer && arg.Res != nil {
var rec func(*Arg)
rec = func(arg1 *Arg) {
if arg1.Kind == ArgGroup {
for _, arg2 := range arg1.Inner {
rec(arg2)
}
return
}
if pad, _ := arg1.IsPad(); pad {
return
}
if arg1.Kind == ArgData && len(arg1.Data) == 0 {
return
}
if arg1.Dir != DirOut {
w.write(ExecInstrCopyin)
w.write(physicalAddr(arg) + w.args[arg1].Offset)
w.writeArg(arg1)
instrSeq++
}
}
rec(arg.Res)
}
})
// Generate the call itself.
w.write(uintptr(c.Meta.ID))
w.write(uintptr(len(c.Args)))
for _, arg := range c.Args {
w.writeArg(arg)
}
w.args[c.Ret] = &argInfo{Idx: instrSeq}
instrSeq++
// Generate copyout instructions that persist interesting return values.
foreachArg(c, func(arg, base *Arg, _ *[]*Arg) {
if len(arg.Uses) == 0 {
return
}
switch arg.Kind {
case ArgReturn:
// Idx is already assigned above.
case ArgConst, ArgResult:
// Create a separate copyout instruction that has own Idx.
if base.Kind != ArgPointer {
panic("arg base is not a pointer")
}
info := w.args[arg]
info.Idx = instrSeq
instrSeq++
w.write(ExecInstrCopyout)
w.write(physicalAddr(base) + info.Offset)
w.write(arg.Size(arg.Type))
default:
panic("bad arg kind in copyout")
}
})
}
w.write(ExecInstrEOF)
return w.buf
}
func physicalAddr(arg *Arg) uintptr {
if arg.Kind != ArgPointer {
panic("physicalAddr: bad arg kind")
}
addr := arg.AddrPage*pageSize + dataOffset
if arg.AddrOffset >= 0 {
addr += uintptr(arg.AddrOffset)
} else {
addr += pageSize - uintptr(-arg.AddrOffset)
}
return addr
}
type execContext struct {
buf []byte
args map[*Arg]*argInfo
}
type argInfo struct {
Offset uintptr // from base pointer
CurSize uintptr
Idx uintptr // instruction index
}
func (w *execContext) write(v uintptr) {
w.buf = append(w.buf, byte(v>>0), byte(v>>8), byte(v>>16), byte(v>>24), byte(v>>32), byte(v>>40), byte(v>>48), byte(v>>56))
}
func (w *execContext) writeArg(arg *Arg) {
switch arg.Kind {
case ArgConst:
w.write(ExecArgConst)
w.write(arg.Size(arg.Type))
w.write(arg.Val)
case ArgResult:
w.write(ExecArgResult)
w.write(arg.Size(arg.Type))
w.write(w.args[arg.Res].Idx)
w.write(arg.OpDiv)
w.write(arg.OpAdd)
case ArgPointer:
w.write(ExecArgConst)
w.write(arg.Size(arg.Type))
w.write(physicalAddr(arg))
case ArgPageSize:
w.write(ExecArgConst)
w.write(arg.Size(arg.Type))
w.write(arg.AddrPage * pageSize)
case ArgData:
w.write(ExecArgData)
w.write(uintptr(len(arg.Data)))
for i := 0; i < len(arg.Data); i += 8 {
var v uintptr
for j := 0; j < 8; j++ {
if i+j >= len(arg.Data) {
break
}
v |= uintptr(arg.Data[i+j]) << uint(j*8)
}
w.write(v)
}
case ArgGroup:
// Squash groups.
for _, arg1 := range arg.Inner {
w.writeArg(arg1)
}
default:
panic("unknown arg type")
}
}
|
