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
|
/*
* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include "linux/config.h"
#include "linux/sched.h"
#include "linux/list.h"
#include "linux/spinlock.h"
#include "linux/slab.h"
#include "linux/errno.h"
#include "linux/mm.h"
#include "asm/current.h"
#include "asm/segment.h"
#include "asm/mmu.h"
#include "asm/pgalloc.h"
#include "asm/pgtable.h"
#include "asm/ldt.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, pmd, proc);
if (!pte)
goto out_pte;
/* There's an interaction between the skas0 stub pages, stack
* randomization, and the BUG at the end of exit_mmap. exit_mmap
* checks that the number of page tables freed is the same as had
* been allocated. If the stack is on the last page table page,
* then the stack pte page will be freed, and if not, it won't. To
* avoid having to know where the stack is, or if the process mapped
* something at the top of its address space for some other reason,
* we set TASK_SIZE to end at the start of the last page table.
* This keeps exit_mmap off the last page, but introduces a leak
* of that page. So, we hang onto it here and free it in
* destroy_context_skas.
*/
mm->context.skas.last_page_table = pmd_page_vaddr(*pmd);
#ifdef CONFIG_3_LEVEL_PGTABLES
mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud));
#endif
*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
*pte = pte_mkexec(*pte);
*pte = pte_wrprotect(*pte);
return(0);
out_pmd:
pud_free(pud);
out_pte:
pmd_free(pmd);
out:
return(-ENOMEM);
}
int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
{
struct mmu_context_skas *from_mm = NULL;
struct mmu_context_skas *to_mm = &mm->context.skas;
unsigned long stack = 0;
int ret = -ENOMEM;
if(skas_needs_stub){
stack = get_zeroed_page(GFP_KERNEL);
if(stack == 0)
goto out;
/* This zeros the entry that pgd_alloc didn't, needed since
* we are about to reinitialize it, and want mm.nr_ptes to
* be accurate.
*/
mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
ret = init_stub_pte(mm, CONFIG_STUB_CODE,
(unsigned long) &__syscall_stub_start);
if(ret)
goto out_free;
ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack);
if(ret)
goto out_free;
mm->nr_ptes--;
}
to_mm->id.stack = stack;
if(current->mm != NULL && current->mm != &init_mm)
from_mm = ¤t->mm->context.skas;
if(proc_mm){
ret = new_mm(stack);
if(ret < 0){
printk("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);
}
ret = init_new_ldt(to_mm, from_mm);
if(ret < 0){
printk("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 destroy_context_skas(struct mm_struct *mm)
{
struct mmu_context_skas *mmu = &mm->context.skas;
if(proc_mm)
os_close_file(mmu->id.u.mm_fd);
else
os_kill_ptraced_process(mmu->id.u.pid, 1);
if(!proc_mm || !ptrace_faultinfo){
free_page(mmu->id.stack);
pte_lock_deinit(virt_to_page(mmu->last_page_table));
pte_free_kernel((pte_t *) mmu->last_page_table);
dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE);
#ifdef CONFIG_3_LEVEL_PGTABLES
pmd_free((pmd_t *) mmu->last_pmd);
#endif
}
}
|
