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6#include <linux/err.h>
7#include <linux/highmem.h>
8#include <linux/mm.h>
9#include <linux/module.h>
10#include <linux/sched.h>
11#include <asm/current.h>
12#include <asm/page.h>
13#include <asm/pgtable.h>
14#include <kern_util.h>
15#include <os.h>
16
17pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
18{
19 pgd_t *pgd;
20 pud_t *pud;
21 pmd_t *pmd;
22
23 if (mm == NULL)
24 return NULL;
25
26 pgd = pgd_offset(mm, addr);
27 if (!pgd_present(*pgd))
28 return NULL;
29
30 pud = pud_offset(pgd, addr);
31 if (!pud_present(*pud))
32 return NULL;
33
34 pmd = pmd_offset(pud, addr);
35 if (!pmd_present(*pmd))
36 return NULL;
37
38 return pte_offset_kernel(pmd, addr);
39}
40
41static pte_t *maybe_map(unsigned long virt, int is_write)
42{
43 pte_t *pte = virt_to_pte(current->mm, virt);
44 int err, dummy_code;
45
46 if ((pte == NULL) || !pte_present(*pte) ||
47 (is_write && !pte_write(*pte))) {
48 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
49 if (err)
50 return NULL;
51 pte = virt_to_pte(current->mm, virt);
52 }
53 if (!pte_present(*pte))
54 pte = NULL;
55
56 return pte;
57}
58
59static int do_op_one_page(unsigned long addr, int len, int is_write,
60 int (*op)(unsigned long addr, int len, void *arg), void *arg)
61{
62 jmp_buf buf;
63 struct page *page;
64 pte_t *pte;
65 int n, faulted;
66
67 pte = maybe_map(addr, is_write);
68 if (pte == NULL)
69 return -1;
70
71 page = pte_page(*pte);
72 addr = (unsigned long) kmap_atomic(page) +
73 (addr & ~PAGE_MASK);
74
75 current->thread.fault_catcher = &buf;
76
77 faulted = UML_SETJMP(&buf);
78 if (faulted == 0)
79 n = (*op)(addr, len, arg);
80 else
81 n = -1;
82
83 current->thread.fault_catcher = NULL;
84
85 kunmap_atomic((void *)addr);
86
87 return n;
88}
89
90static int buffer_op(unsigned long addr, int len, int is_write,
91 int (*op)(unsigned long, int, void *), void *arg)
92{
93 int size, remain, n;
94
95 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
96 remain = len;
97
98 n = do_op_one_page(addr, size, is_write, op, arg);
99 if (n != 0) {
100 remain = (n < 0 ? remain : 0);
101 goto out;
102 }
103
104 addr += size;
105 remain -= size;
106 if (remain == 0)
107 goto out;
108
109 while (addr < ((addr + remain) & PAGE_MASK)) {
110 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
111 if (n != 0) {
112 remain = (n < 0 ? remain : 0);
113 goto out;
114 }
115
116 addr += PAGE_SIZE;
117 remain -= PAGE_SIZE;
118 }
119 if (remain == 0)
120 goto out;
121
122 n = do_op_one_page(addr, remain, is_write, op, arg);
123 if (n != 0) {
124 remain = (n < 0 ? remain : 0);
125 goto out;
126 }
127
128 return 0;
129 out:
130 return remain;
131}
132
133static int copy_chunk_from_user(unsigned long from, int len, void *arg)
134{
135 unsigned long *to_ptr = arg, to = *to_ptr;
136
137 memcpy((void *) to, (void *) from, len);
138 *to_ptr += len;
139 return 0;
140}
141
142int copy_from_user(void *to, const void __user *from, int n)
143{
144 if (segment_eq(get_fs(), KERNEL_DS)) {
145 memcpy(to, (__force void*)from, n);
146 return 0;
147 }
148
149 return access_ok(VERIFY_READ, from, n) ?
150 buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
151 n;
152}
153EXPORT_SYMBOL(copy_from_user);
154
155static int copy_chunk_to_user(unsigned long to, int len, void *arg)
156{
157 unsigned long *from_ptr = arg, from = *from_ptr;
158
159 memcpy((void *) to, (void *) from, len);
160 *from_ptr += len;
161 return 0;
162}
163
164int copy_to_user(void __user *to, const void *from, int n)
165{
166 if (segment_eq(get_fs(), KERNEL_DS)) {
167 memcpy((__force void *) to, from, n);
168 return 0;
169 }
170
171 return access_ok(VERIFY_WRITE, to, n) ?
172 buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
173 n;
174}
175EXPORT_SYMBOL(copy_to_user);
176
177static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
178{
179 char **to_ptr = arg, *to = *to_ptr;
180 int n;
181
182 strncpy(to, (void *) from, len);
183 n = strnlen(to, len);
184 *to_ptr += n;
185
186 if (n < len)
187 return 1;
188 return 0;
189}
190
191int strncpy_from_user(char *dst, const char __user *src, int count)
192{
193 int n;
194 char *ptr = dst;
195
196 if (segment_eq(get_fs(), KERNEL_DS)) {
197 strncpy(dst, (__force void *) src, count);
198 return strnlen(dst, count);
199 }
200
201 if (!access_ok(VERIFY_READ, src, 1))
202 return -EFAULT;
203
204 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
205 &ptr);
206 if (n != 0)
207 return -EFAULT;
208 return strnlen(dst, count);
209}
210EXPORT_SYMBOL(strncpy_from_user);
211
212static int clear_chunk(unsigned long addr, int len, void *unused)
213{
214 memset((void *) addr, 0, len);
215 return 0;
216}
217
218int __clear_user(void __user *mem, int len)
219{
220 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
221}
222
223int clear_user(void __user *mem, int len)
224{
225 if (segment_eq(get_fs(), KERNEL_DS)) {
226 memset((__force void*)mem, 0, len);
227 return 0;
228 }
229
230 return access_ok(VERIFY_WRITE, mem, len) ?
231 buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len;
232}
233EXPORT_SYMBOL(clear_user);
234
235static int strnlen_chunk(unsigned long str, int len, void *arg)
236{
237 int *len_ptr = arg, n;
238
239 n = strnlen((void *) str, len);
240 *len_ptr += n;
241
242 if (n < len)
243 return 1;
244 return 0;
245}
246
247int strnlen_user(const void __user *str, int len)
248{
249 int count = 0, n;
250
251 if (segment_eq(get_fs(), KERNEL_DS))
252 return strnlen((__force char*)str, len) + 1;
253
254 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
255 if (n == 0)
256 return count + 1;
257 return 0;
258}
259EXPORT_SYMBOL(strnlen_user);
260
