-
Notifications
You must be signed in to change notification settings - Fork 1
/
write_capture.go
214 lines (200 loc) · 6.57 KB
/
write_capture.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
210
211
212
213
214
package ebpf
import (
"bytes"
"context"
"fmt"
"io"
"os"
"path"
"strings"
"github.com/nextlinux/tracee/pkg/bufferdecoder"
"github.com/nextlinux/tracee/pkg/errfmt"
"github.com/nextlinux/tracee/pkg/logger"
"github.com/nextlinux/tracee/pkg/utils"
)
func (t *Tracee) processFileWrites(ctx context.Context) {
logger.Debugw("Starting processFileWrites goroutine")
defer logger.Debugw("Stopped processFileWrites goroutine")
const (
// stat_S_IFMT uint32 = 0170000 // bit mask for the file type bit field
_S_IFSOCK uint32 = 0140000 // socket
_S_IFLNK uint32 = 0120000 // symbolic link
_S_IFREG uint32 = 0100000 // regular file
_S_IFBLK uint32 = 0060000 // block device
_S_IFDIR uint32 = 0040000 // directory
_S_IFCHR uint32 = 0020000 // character device
_S_IFIFO uint32 = 0010000 // FIFO
)
for {
select {
case dataRaw := <-t.fileWrChannel:
if len(dataRaw) == 0 {
continue
}
ebpfMsgDecoder := bufferdecoder.New(dataRaw)
var meta bufferdecoder.ChunkMeta
appendFile := false
err := ebpfMsgDecoder.DecodeChunkMeta(&meta)
if err != nil {
t.handleError(err)
continue
}
if meta.Size <= 0 {
t.handleError(errfmt.Errorf("invalid chunk size: %d", meta.Size))
continue
}
if ebpfMsgDecoder.BuffLen() < int(meta.Size) {
t.handleError(errfmt.Errorf("chunk too large: %d", meta.Size))
continue
}
containerId := t.containers.GetCgroupInfo(meta.CgroupID).Container.ContainerId
if containerId == "" {
containerId = "host"
}
pathname := containerId
if err := utils.MkdirAtExist(t.OutDir, pathname, 0755); err != nil {
t.handleError(err)
continue
}
filename := ""
metaBuffDecoder := bufferdecoder.New(meta.Metadata[:])
var kernelModuleMeta bufferdecoder.KernelModuleMeta
var bpfObjectMeta bufferdecoder.BpfObjectMeta
if meta.BinType == bufferdecoder.SendVfsWrite {
var vfsMeta bufferdecoder.VfsWriteMeta
err = metaBuffDecoder.DecodeVfsWriteMeta(&vfsMeta)
if err != nil {
t.handleError(err)
continue
}
if vfsMeta.Mode&_S_IFSOCK == _S_IFSOCK || vfsMeta.Mode&_S_IFCHR == _S_IFCHR || vfsMeta.Mode&_S_IFIFO == _S_IFIFO {
appendFile = true
}
if vfsMeta.Pid == 0 {
filename = fmt.Sprintf("write.dev-%d.inode-%d", vfsMeta.DevID, vfsMeta.Inode)
} else {
filename = fmt.Sprintf("write.dev-%d.inode-%d.pid-%d", vfsMeta.DevID, vfsMeta.Inode, vfsMeta.Pid)
}
} else if meta.BinType == bufferdecoder.SendMprotect {
var mprotectMeta bufferdecoder.MprotectWriteMeta
err = metaBuffDecoder.DecodeMprotectWriteMeta(&mprotectMeta)
if err != nil {
t.handleError(err)
continue
}
// note: size of buffer will determine maximum extracted file size! (as writes from kernel are immediate)
if t.config.Output.RelativeTime {
// To get the monotonic time since tracee was started, we have to subtract the start time from the timestamp.
mprotectMeta.Ts -= t.startTime
} else {
// To get the current ("wall") time, we add the boot time into it.
mprotectMeta.Ts += t.bootTime
}
filename = fmt.Sprintf("bin.pid-%d.ts-%d", mprotectMeta.Pid, mprotectMeta.Ts)
} else if meta.BinType == bufferdecoder.SendKernelModule {
err = metaBuffDecoder.DecodeKernelModuleMeta(&kernelModuleMeta)
if err != nil {
t.handleError(err)
continue
}
filename = "module"
if kernelModuleMeta.DevID != 0 {
filename = fmt.Sprintf("%s.dev-%d", filename, kernelModuleMeta.DevID)
}
if kernelModuleMeta.Inode != 0 {
filename = fmt.Sprintf("%s.inode-%d", filename, kernelModuleMeta.Inode)
}
if kernelModuleMeta.Pid != 0 {
filename = fmt.Sprintf("%s.pid-%d", filename, kernelModuleMeta.Pid)
}
} else if meta.BinType == bufferdecoder.SendBpfObject {
err = metaBuffDecoder.DecodeBpfObjectMeta(&bpfObjectMeta)
if err != nil {
t.handleError(err)
continue
}
bpfName := string(bytes.TrimRight(bpfObjectMeta.Name[:], "\x00"))
filename = fmt.Sprintf("bpf.name-%s", bpfName)
if bpfObjectMeta.Pid != 0 {
filename = fmt.Sprintf("%s.pid-%d", filename, bpfObjectMeta.Pid)
}
filename = fmt.Sprintf("%s.%d", filename, bpfObjectMeta.Rand)
} else {
t.handleError(errfmt.Errorf("unknown binary type: %d", meta.BinType))
continue
}
fullname := path.Join(pathname, filename)
f, err := utils.OpenAt(t.OutDir, fullname, os.O_CREATE|os.O_WRONLY, 0640)
if err != nil {
t.handleError(err)
continue
}
if appendFile {
if _, err := f.Seek(0, io.SeekEnd); err != nil {
if err := f.Close(); err != nil {
t.handleError(err)
}
t.handleError(err)
continue
}
} else {
if _, err := f.Seek(int64(meta.Off), io.SeekStart); err != nil {
if err := f.Close(); err != nil {
t.handleError(err)
}
t.handleError(err)
continue
}
}
dataBytes, err := bufferdecoder.ReadByteSliceFromBuff(ebpfMsgDecoder, int(meta.Size))
if err != nil {
if err := f.Close(); err != nil {
t.handleError(err)
}
t.handleError(err)
continue
}
if _, err := f.Write(dataBytes); err != nil {
if err := f.Close(); err != nil {
t.handleError(err)
}
t.handleError(err)
continue
}
if err := f.Close(); err != nil {
t.handleError(err)
continue
}
// Rename the file to add hash when last chunk was received
if meta.BinType == bufferdecoder.SendKernelModule && uint32(meta.Size)+uint32(meta.Off) == kernelModuleMeta.Size {
fileHash, _ := t.computeOutFileHash(fullname)
err := utils.RenameAt(t.OutDir, fullname, t.OutDir, fullname+"."+fileHash)
if err != nil {
t.handleError(err)
continue
}
} else if meta.BinType == bufferdecoder.SendBpfObject && (uint32(meta.Size)+uint32(meta.Off)) == bpfObjectMeta.Size {
fileHash, _ := t.computeOutFileHash(fullname)
// Delete the random int used to differentiate files
dotIndex := strings.LastIndex(fullname, ".")
err := utils.RenameAt(t.OutDir, fullname, t.OutDir, fullname[:dotIndex]+"."+fileHash)
if err != nil {
t.handleError(err)
continue
}
}
case lost := <-t.lostWrChannel:
// When terminating tracee-ebpf the lost channel receives multiple "0 lost events" events.
// This check prevents those 0 lost events messages to be written to stderr until the bug is fixed:
// https://github.com/aquasecurity/libbpfgo/issues/122
if lost > 0 {
if err := t.stats.LostWrCount.Increment(lost); err != nil {
logger.Errorw("Incrementing lost write count", "error", err)
}
logger.Warnw(fmt.Sprintf("Lost %d write events", lost))
}
case <-ctx.Done():
return
}
}
}