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
|
/*
* linux/kernel/ptrace.c
*
* (C) Copyright 1999 Linus Torvalds
*
* Common interfaces for "ptrace()" which we do not want
* to continually duplicate across every architecture.
*/
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/smp_lock.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
/*
* Access another process' address space, one page at a time.
*/
static int access_one_page(struct mm_struct * mm, struct vm_area_struct * vma, unsigned long addr, void *buf, int len, int write)
{
pgd_t * pgdir;
pmd_t * pgmiddle;
pte_t * pgtable;
char *maddr;
struct page *page;
repeat:
spin_lock(&mm->page_table_lock);
pgdir = pgd_offset(vma->vm_mm, addr);
if (pgd_none(*pgdir))
goto fault_in_page;
if (pgd_bad(*pgdir))
goto bad_pgd;
pgmiddle = pmd_offset(pgdir, addr);
if (pmd_none(*pgmiddle))
goto fault_in_page;
if (pmd_bad(*pgmiddle))
goto bad_pmd;
pgtable = pte_offset(pgmiddle, addr);
if (!pte_present(*pgtable))
goto fault_in_page;
if (write && (!pte_write(*pgtable) || !pte_dirty(*pgtable)))
goto fault_in_page;
page = pte_page(*pgtable);
/* ZERO_PAGE is special: reads from it are ok even though it's marked reserved */
if (page != ZERO_PAGE(addr) || write) {
if ((!VALID_PAGE(page)) || PageReserved(page)) {
spin_unlock(&mm->page_table_lock);
return 0;
}
}
get_page(page);
spin_unlock(&mm->page_table_lock);
flush_cache_page(vma, addr);
if (write) {
maddr = kmap(page);
memcpy(maddr + (addr & ~PAGE_MASK), buf, len);
flush_page_to_ram(page);
flush_icache_page(vma, page);
kunmap(page);
} else {
maddr = kmap(page);
memcpy(buf, maddr + (addr & ~PAGE_MASK), len);
flush_page_to_ram(page);
kunmap(page);
}
put_page(page);
return len;
fault_in_page:
spin_unlock(&mm->page_table_lock);
/* -1: out of memory. 0 - unmapped page */
if (handle_mm_fault(mm, vma, addr, write) > 0)
goto repeat;
return 0;
bad_pgd:
spin_unlock(&mm->page_table_lock);
pgd_ERROR(*pgdir);
return 0;
bad_pmd:
spin_unlock(&mm->page_table_lock);
pmd_ERROR(*pgmiddle);
return 0;
}
static int access_mm(struct mm_struct *mm, struct vm_area_struct * vma, unsigned long addr, void *buf, int len, int write)
{
int copied = 0;
for (;;) {
unsigned long offset = addr & ~PAGE_MASK;
int this_len = PAGE_SIZE - offset;
int retval;
if (this_len > len)
this_len = len;
retval = access_one_page(mm, vma, addr, buf, this_len, write);
copied += retval;
if (retval != this_len)
break;
len -= retval;
if (!len)
break;
addr += retval;
buf += retval;
if (addr < vma->vm_end)
continue;
if (!vma->vm_next)
break;
if (vma->vm_next->vm_start != vma->vm_end)
break;
vma = vma->vm_next;
}
return copied;
}
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
int copied;
struct mm_struct *mm;
struct vm_area_struct * vma;
/* Worry about races with exit() */
task_lock(tsk);
mm = tsk->mm;
if (mm)
atomic_inc(&mm->mm_users);
task_unlock(tsk);
if (!mm)
return 0;
down_read(&mm->mmap_sem);
vma = find_extend_vma(mm, addr);
copied = 0;
if (vma)
copied = access_mm(mm, vma, addr, buf, len, write);
up_read(&mm->mmap_sem);
mmput(mm);
return copied;
}
int ptrace_readdata(struct task_struct *tsk, unsigned long src, char *dst, int len)
{
int copied = 0;
while (len > 0) {
char buf[128];
int this_len, retval;
this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
retval = access_process_vm(tsk, src, buf, this_len, 0);
if (!retval) {
if (copied)
break;
return -EIO;
}
if (copy_to_user(dst, buf, retval))
return -EFAULT;
copied += retval;
src += retval;
dst += retval;
len -= retval;
}
return copied;
}
int ptrace_writedata(struct task_struct *tsk, char * src, unsigned long dst, int len)
{
int copied = 0;
while (len > 0) {
char buf[128];
int this_len, retval;
this_len = (len > sizeof(buf)) ? sizeof(buf) : len;
if (copy_from_user(buf, src, this_len))
return -EFAULT;
retval = access_process_vm(tsk, dst, buf, this_len, 1);
if (!retval) {
if (copied)
break;
return -EIO;
}
copied += retval;
src += retval;
dst += retval;
len -= retval;
}
return copied;
}
|
