15
Ben bu basit çekirdek modülü yazdı:Acemi: çağrı kodu nerede?
#include <linux/module.h> // for printk()
int init(void)
{
printk("n Kello, everybody! nn");
return 0;
}
void exit(void)
{
printk("n Goodbye now... nn");
}
MODULE_LICENSE("GPL");
module_init(init);
module_exit(exit);
ve ben kod asm için tercüme nasıl anlamaya çalışıyorum, bu yüzden objdumped:
[email protected]:/home/alex/Desktop/KModule# objdump -D kmodule.ko
kmodule.ko: file format elf64-x86-64
Disassembly of section .note.gnu.build-id:
0000000000000000 <.note.gnu.build-id>:
0: 04 00 add $0x0,%al
2: 00 00 add %al,(%rax)
4: 14 00 adc $0x0,%al
6: 00 00 add %al,(%rax)
8: 03 00 add (%rax),%eax
a: 00 00 add %al,(%rax)
c: 47 rex.RXB
d: 4e 55 rex.WRX push %rbp
f: 00 5e ef add %bl,-0x11(%rsi)
12: 7d 73 jge 87 <__mod_vermagic5+0x4f>
14: 83 47 e9 4d addl $0x4d,-0x17(%rdi)
18: 98 cwtl
19: eb b8 jmp ffffffffffffffd3 <__mod_vermagic5+0xffffffffffffff9b>
1b: eb 18 jmp 35 <__module_depends+0x6>
1d: fb sti
1e: 84 28 test %ch,(%rax)
20: 73 db jae fffffffffffffffd <__mod_vermagic5+0xffffffffffffffc5>
22: 51 push %rcx
23: e4 .byte 0xe4
Disassembly of section .text:
0000000000000000 <init>:
0: 55 push %rbp
1: 48 89 e5 mov %rsp,%rbp
4: e8 00 00 00 00 callq 9 <init+0x9>
9: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
10: 31 c0 xor %eax,%eax
12: e8 00 00 00 00 callq 17 <init+0x17>
17: 31 c0 xor %eax,%eax
19: 5d pop %rbp
1a: c3 retq
1b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
0000000000000020 <cleanup_module>:
20: 55 push %rbp
21: 48 89 e5 mov %rsp,%rbp
24: e8 00 00 00 00 callq 29 <cleanup_module+0x9>
29: 48 c7 c7 00 00 00 00 mov $0x0,%rdi
30: 31 c0 xor %eax,%eax
32: e8 00 00 00 00 callq 37 <cleanup_module+0x17>
37: 5d pop %rbp
38: c3 retq
39: 00 00 add %al,(%rax)
...
Disassembly of section .rodata.str1.1:
0000000000000000 <.rodata.str1.1>:
0: 0a 20 or (%rax),%ah
2: 20 20 and %ah,(%rax)
4: 4b rex.WXB
5: 65 gs
6: 6c insb (%dx),%es:(%rdi)
7: 6c insb (%dx),%es:(%rdi)
8: 6f outsl %ds:(%rsi),(%dx)
9: 2c 20 sub $0x20,%al
b: 65 gs
c: 76 65 jbe 73 <__mod_vermagic5+0x3b>
e: 72 79 jb 89 <__mod_vermagic5+0x51>
10: 62 (bad)
11: 6f outsl %ds:(%rsi),(%dx)
12: 64 fs
13: 79 21 jns 36 <__module_depends+0x7>
15: 20 0a and %cl,(%rdx)
17: 0a 00 or (%rax),%al
19: 0a 20 or (%rax),%ah
1b: 20 20 and %ah,(%rax)
1d: 47 6f rex.RXB outsl %ds:(%rsi),(%dx)
1f: 6f outsl %ds:(%rsi),(%dx)
20: 64 fs
21: 62 (bad)
22: 79 65 jns 89 <__mod_vermagic5+0x51>
24: 20 6e 6f and %ch,0x6f(%rsi)
27: 77 2e ja 57 <__mod_vermagic5+0x1f>
29: 2e 2e 20 0a cs and %cl,%cs:(%rdx)
2d: 0a 00 or (%rax),%al
Disassembly of section .modinfo:
0000000000000000 <__mod_license27>:
0: 6c insb (%dx),%es:(%rdi)
1: 69 63 65 6e 73 65 3d imul $0x3d65736e,0x65(%rbx),%esp
8: 47 50 rex.RXB push %r8
a: 4c 00 73 72 rex.WR add %r14b,0x72(%rbx)
000000000000000c <__mod_srcversion31>:
c: 73 72 jae 80 <__mod_vermagic5+0x48>
e: 63 76 65 movslq 0x65(%rsi),%esi
11: 72 73 jb 86 <__mod_vermagic5+0x4e>
13: 69 6f 6e 3d 45 33 46 imul $0x4633453d,0x6e(%rdi),%ebp
1a: 38 45 32 cmp %al,0x32(%rbp)
1d: 30 39 xor %bh,(%rcx)
1f: 34 37 xor $0x37,%al
21: 44 32 31 xor (%rcx),%r14b
24: 33 30 xor (%rax),%esi
26: 32 35 44 36 39 34 xor 0x34393644(%rip),%dh # 34393670 <__mod_vermagic5+0x34393638>
2c: 34 45 xor $0x45,%al
...
000000000000002f <__module_depends>:
2f: 64 fs
30: 65 gs
31: 70 65 jo 98 <__mod_vermagic5+0x60>
33: 6e outsb %ds:(%rsi),(%dx)
34: 64 fs
35: 73 3d jae 74 <__mod_vermagic5+0x3c>
...
0000000000000038 <__mod_vermagic5>:
38: 76 65 jbe 9f <__mod_vermagic5+0x67>
3a: 72 6d jb a9 <__mod_vermagic5+0x71>
3c: 61 (bad)
3d: 67 69 63 3d 33 2e 30 imul $0x2e302e33,0x3d(%ebx),%esp
44: 2e
45: 30 2d 31 36 2d 67 xor %ch,0x672d3631(%rip) # 672d367c <__mod_vermagic5+0x672d3644>
4b: 65 6e outsb %gs:(%rsi),(%dx)
4d: 65 gs
4e: 72 69 jb b9 <__mod_vermagic5+0x81>
50: 63 20 movslq (%rax),%esp
52: 53 push %rbx
53: 4d 50 rex.WRB push %r8
55: 20 6d 6f and %ch,0x6f(%rbp)
58: 64 fs
59: 5f pop %rdi
5a: 75 6e jne ca <__mod_vermagic5+0x92>
5c: 6c insb (%dx),%es:(%rdi)
5d: 6f outsl %ds:(%rsi),(%dx)
5e: 61 (bad)
5f: 64 20 6d 6f and %ch,%fs:0x6f(%rbp)
63: 64 fs
64: 76 65 jbe cb <__mod_vermagic5+0x93>
66: 72 73 jb db <__mod_vermagic5+0xa3>
68: 69 .byte 0x69
69: 6f outsl %ds:(%rsi),(%dx)
6a: 6e outsb %ds:(%rsi),(%dx)
6b: 73 20 jae 8d <__mod_vermagic5+0x55>
...
Disassembly of section __mcount_loc:
0000000000000000 <__mcount_loc>:
...
Disassembly of section __versions:
0000000000000000 <____versions>:
0: 73 24 jae 26 <____versions+0x26>
2: 57 push %rdi
3: 41 00 00 add %al,(%r8)
6: 00 00 add %al,(%rax)
8: 6d insl (%dx),%es:(%rdi)
9: 6f outsl %ds:(%rsi),(%dx)
a: 64 fs
b: 75 6c jne 79 <____versions+0x79>
d: 65 gs
e: 5f pop %rdi
f: 6c insb (%dx),%es:(%rdi)
10: 61 (bad)
11: 79 6f jns 82 <____versions+0x82>
13: 75 74 jne 89 <____versions+0x89>
...
3d: 00 00 add %al,(%rax)
3f: 00 49 a0 add %cl,-0x60(%rcx)
42: e1 27 loope 6b <____versions+0x6b>
44: 00 00 add %al,(%rax)
46: 00 00 add %al,(%rax)
48: 70 72 jo bc <____versions+0xbc>
4a: 69 6e 74 6b 00 00 00 imul $0x6b,0x74(%rsi),%ebp
...
7d: 00 00 add %al,(%rax)
7f: 00 9a 0f 39 b4 00 add %bl,0xb4390f(%rdx)
85: 00 00 add %al,(%rax)
87: 00 6d 63 add %ch,0x63(%rbp)
8a: 6f outsl %ds:(%rsi),(%dx)
8b: 75 6e jne fb <__mod_vermagic5+0xc3>
8d: 74 00 je 8f <____versions+0x8f>
...
Disassembly of section .gnu.linkonce.this_module:
0000000000000000 <__this_module>:
...
18: 6b 6d 6f 64 imul $0x64,0x6f(%rbp),%ebp
1c: 75 6c jne 8a <__this_module+0x8a>
1e: 65 00 00 add %al,%gs:(%rax)
...
Disassembly of section .comment:
0000000000000000 <.comment>:
0: 00 47 43 add %al,0x43(%rdi)
3: 43 3a 20 rex.XB cmp (%r8),%spl
6: 28 55 62 sub %dl,0x62(%rbp)
9: 75 6e jne 79 <__mod_vermagic5+0x41>
b: 74 75 je 82 <__mod_vermagic5+0x4a>
d: 2f (bad)
e: 4c 69 6e 61 72 6f 20 imul $0x34206f72,0x61(%rsi),%r13
15: 34
16: 2e 36 2e 31 2d 39 75 cs ss xor %ebp,%cs:%ss:0x75627539(%rip) # 75627558 <__mod_vermagic5+0x75627520>
1d: 62 75
1f: 6e outsb %ds:(%rsi),(%dx)
20: 74 75 je 97 <__mod_vermagic5+0x5f>
22: 33 29 xor (%rcx),%ebp
24: 20 34 2e and %dh,(%rsi,%rbp,1)
27: 36 2e 31 00 ss xor %eax,%cs:%ss:(%rax)
2b: 00 47 43 add %al,0x43(%rdi)
2e: 43 3a 20 rex.XB cmp (%r8),%spl
31: 28 55 62 sub %dl,0x62(%rbp)
34: 75 6e jne a4 <__mod_vermagic5+0x6c>
36: 74 75 je ad <__mod_vermagic5+0x75>
38: 2f (bad)
39: 4c 69 6e 61 72 6f 20 imul $0x34206f72,0x61(%rsi),%r13
40: 34
41: 2e 36 2e 31 2d 39 75 cs ss xor %ebp,%cs:%ss:0x75627539(%rip) # 75627583 <__mod_vermagic5+0x7562754b>
48: 62 75
4a: 6e outsb %ds:(%rsi),(%dx)
4b: 74 75 je c2 <__mod_vermagic5+0x8a>
4d: 33 29 xor (%rcx),%ebp
4f: 20 34 2e and %dh,(%rsi,%rbp,1)
52: 36 2e 31 00 ss xor %eax,%cs:%ss:(%rax)
ama bir şey çok yığın yapar değil geri kalanı ile ...
Baskık işlevi nasıl çağrılır? Sadece "callq 9" görebiliyorum, ve bu ofset bana bir şey söylemiyor .. sıradaki talimat ... bu ne? "Kello" mesajı doğru şekilde yazdırılıyor ancak bu durumda kodu bulamıyorum!
Ayrıca bu kod, .rodata.str1.1 bölümünde "Kello etc .." dizesine nasıl erişebilir? Bu, ds kaydına eşlenmiş bir program segmenti ise, buna erişmek için "ds: 0" gibi bir şey olmamalıdır?
Oldukça karıştı ..