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
|
/*
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include "linux/mm.h"
#include "linux/sched.h"
#include "linux/slab.h"
#include "asm/pgalloc.h"
#include "asm/pgtable.h"
#include "as-layout.h"
#include "os.h"
#include "skas.h"
extern int __syscall_stub_start;
static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
unsigned long kernel)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pgd = pgd_offset(mm, proc);
pud = pud_alloc(mm, pgd, proc);
if (!pud)
goto out;
pmd = pmd_alloc(mm, pud, proc);
if (!pmd)
goto out_pmd;
pte = pte_alloc_map(mm, NULL, pmd, proc);
if (!pte)
goto out_pte;
*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
*pte = pte_mkread(*pte);
return 0;
out_pte:
pmd_free(mm, pmd);
out_pmd:
pud_free(mm, pud);
out:
return -ENOMEM;
}
int init_new_context(struct task_struct *task, struct mm_struct *mm)
{
struct mm_context *from_mm = NULL;
struct mm_context *to_mm = &mm->context;
unsigned long stack = 0;
int ret = -ENOMEM;
if (skas_needs_stub) {
stack = get_zeroed_page(GFP_KERNEL);
if (stack == 0)
goto out;
}
to_mm->id.stack = stack;
if (current->mm != NULL && current->mm != &init_mm)
from_mm = ¤t->mm->context;
if (proc_mm) {
ret = new_mm(stack);
if (ret < 0) {
printk(KERN_ERR "init_new_context_skas - "
"new_mm failed, errno = %d\n", ret);
goto out_free;
}
to_mm->id.u.mm_fd = ret;
}
else {
if (from_mm)
to_mm->id.u.pid = copy_context_skas0(stack,
from_mm->id.u.pid);
else to_mm->id.u.pid = start_userspace(stack);
if (to_mm->id.u.pid < 0) {
ret = to_mm->id.u.pid;
goto out_free;
}
}
ret = init_new_ldt(to_mm, from_mm);
if (ret < 0) {
printk(KERN_ERR "init_new_context_skas - init_ldt"
" failed, errno = %d\n", ret);
goto out_free;
}
return 0;
out_free:
if (to_mm->id.stack != 0)
free_page(to_mm->id.stack);
out:
return ret;
}
void uml_setup_stubs(struct mm_struct *mm)
{
int err, ret;
if (!skas_needs_stub)
return;
ret = init_stub_pte(mm, STUB_CODE,
(unsigned long) &__syscall_stub_start);
if (ret)
goto out;
ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
if (ret)
goto out;
mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start);
mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
/* dup_mmap already holds mmap_sem */
err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
VM_READ | VM_MAYREAD | VM_EXEC |
VM_MAYEXEC | VM_DONTCOPY,
mm->context.stub_pages);
if (err) {
printk(KERN_ERR "install_special_mapping returned %d\n", err);
goto out;
}
return;
out:
force_sigsegv(SIGSEGV, current);
}
void arch_exit_mmap(struct mm_struct *mm)
{
pte_t *pte;
pte = virt_to_pte(mm, STUB_CODE);
if (pte != NULL)
pte_clear(mm, STUB_CODE, pte);
pte = virt_to_pte(mm, STUB_DATA);
if (pte == NULL)
return;
pte_clear(mm, STUB_DATA, pte);
}
void destroy_context(struct mm_struct *mm)
{
struct mm_context *mmu = &mm->context;
if (proc_mm)
os_close_file(mmu->id.u.mm_fd);
else {
/*
* If init_new_context wasn't called, this will be
* zero, resulting in a kill(0), which will result in the
* whole UML suddenly dying. Also, cover negative and
* 1 cases, since they shouldn't happen either.
*/
if (mmu->id.u.pid < 2) {
printk(KERN_ERR "corrupt mm_context - pid = %d\n",
mmu->id.u.pid);
return;
}
os_kill_ptraced_process(mmu->id.u.pid, 1);
}
if (skas_needs_stub)
free_page(mmu->id.stack);
free_ldt(mmu);
}
|
