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
|
package main
import (
"bufio"
"errors"
"fmt"
"log"
"os"
"strings"
"syscall"
)
func parseUint32Fast(s string) (int, error) {
sLen := len(s)
if sLen < 1 {
return -1, errors.New("zero length string")
}
if sLen > 10 {
return -1, errors.New("string too long")
}
n := 0
for i, ch := range []byte(s) {
ch -= '0'
if ch > 9 {
return -1, fmt.Errorf("invalid character '%s' at index %d", string([]byte{ch}), i)
}
n = n*10 + int(ch)
}
return n, nil
}
func parseConfig(p string, puid int) (fid int, ok bool) {
// refuse to run if fsurc is not protected correctly
if s, err := os.Stat(p); err != nil {
log.Fatal(err)
} else if s.Mode().Perm() != 0400 {
log.Fatal("bad fsurc perm")
} else if st := s.Sys().(*syscall.Stat_t); st.Uid != 0 || st.Gid != 0 {
log.Fatal("fsurc must be owned by uid 0")
}
if r, err := os.Open(p); err != nil {
log.Fatal(err)
return -1, false
} else {
s := bufio.NewScanner(r)
var line int
for s.Scan() {
line++
// <puid> <fid>
lf := strings.SplitN(s.Text(), " ", 2)
if len(lf) != 2 {
log.Fatalf("invalid entry on line %d", line)
}
var puid0 int
if puid0, err = parseUint32Fast(lf[0]); err != nil || puid0 < 1 {
log.Fatalf("invalid parent uid on line %d", line)
}
ok = puid0 == puid
if ok {
// allowed fid range 0 to 99
if fid, err = parseUint32Fast(lf[1]); err != nil || fid < 0 || fid > 99 {
log.Fatalf("invalid fortify uid on line %d", line)
}
return
}
}
if err = s.Err(); err != nil {
log.Fatalf("cannot read fsurc: %v", err)
}
return -1, false
}
}
|
