1 /*
2 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6 #include <linux/err.h>
7 #include <linux/highmem.h>
8 #include <linux/mm.h>
9 #include <linux/sched.h>
10 #include <asm/current.h>
11 #include <asm/page.h>
12 #include <asm/pgtable.h>
13 #include "kern_util.h"
14 #include "os.h"
15
16 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
17 {
18 pgd_t *pgd;
19 pud_t *pud;
20 pmd_t *pmd;
21
22 if (mm == NULL)
23 return NULL;
24
25 pgd = pgd_offset(mm, addr);
26 if (!pgd_present(*pgd))
27 return NULL;
28
29 pud = pud_offset(pgd, addr);
30 if (!pud_present(*pud))
31 return NULL;
32
33 pmd = pmd_offset(pud, addr);
34 if (!pmd_present(*pmd))
35 return NULL;
36
37 return pte_offset_kernel(pmd, addr);
38 }
39
40 static pte_t *maybe_map(unsigned long virt, int is_write)
41 {
42 pte_t *pte = virt_to_pte(current->mm, virt);
43 int err, dummy_code;
44
45 if ((pte == NULL) || !pte_present(*pte) ||
46 (is_write && !pte_write(*pte))) {
47 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
48 if (err)
49 return NULL;
50 pte = virt_to_pte(current->mm, virt);
51 }
52 if (!pte_present(*pte))
53 pte = NULL;
54
55 return pte;
56 }
57
58 static int do_op_one_page(unsigned long addr, int len, int is_write,
59 int (*op)(unsigned long addr, int len, void *arg), void *arg)
60 {
61 jmp_buf buf;
62 struct page *page;
63 pte_t *pte;
64 int n, faulted;
65
66 pte = maybe_map(addr, is_write);
67 if (pte == NULL)
68 return -1;
69
70 page = pte_page(*pte);
71 addr = (unsigned long) kmap_atomic(page, KM_UML_USERCOPY) +
72 (addr & ~PAGE_MASK);
73
74 current->thread.fault_catcher = &buf;
75
76 faulted = UML_SETJMP(&buf);
77 if (faulted == 0)
78 n = (*op)(addr, len, arg);
79 else
80 n = -1;
81
82 current->thread.fault_catcher = NULL;
83
84 kunmap_atomic(page, KM_UML_USERCOPY);
85
86 return n;
87 }
88
89 static int buffer_op(unsigned long addr, int len, int is_write,
90 int (*op)(unsigned long, int, void *), void *arg)
91 {
92 int size, remain, n;
93
94 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
95 remain = len;
96
97 n = do_op_one_page(addr, size, is_write, op, arg);
98 if (n != 0) {
99 remain = (n < 0 ? remain : 0);
100 goto out;
101 }
102
103 addr += size;
104 remain -= size;
105 if (remain == 0)
106 goto out;
107
108 while (addr < ((addr + remain) & PAGE_MASK)) {
109 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
110 if (n != 0) {
111 remain = (n < 0 ? remain : 0);
112 goto out;
113 }
114
115 addr += PAGE_SIZE;
116 remain -= PAGE_SIZE;
117 }
118 if (remain == 0)
119 goto out;
120
121 n = do_op_one_page(addr, remain, is_write, op, arg);
122 if (n != 0) {
123 remain = (n < 0 ? remain : 0);
124 goto out;
125 }
126
127 return 0;
128 out:
129 return remain;
130 }
131
132 static int copy_chunk_from_user(unsigned long from, int len, void *arg)
133 {
134 unsigned long *to_ptr = arg, to = *to_ptr;
135
136 memcpy((void *) to, (void *) from, len);
137 *to_ptr += len;
138 return 0;
139 }
140
141 int copy_from_user(void *to, const void __user *from, int n)
142 {
143 if (segment_eq(get_fs(), KERNEL_DS)) {
144 memcpy(to, (__force void*)from, n);
145 return 0;
146 }
147
148 return access_ok(VERIFY_READ, from, n) ?
149 buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
150 n;
151 }
152
153 static int copy_chunk_to_user(unsigned long to, int len, void *arg)
154 {
155 unsigned long *from_ptr = arg, from = *from_ptr;
156
157 memcpy((void *) to, (void *) from, len);
158 *from_ptr += len;
159 return 0;
160 }
161
162 int copy_to_user(void __user *to, const void *from, int n)
163 {
164 if (segment_eq(get_fs(), KERNEL_DS)) {
165 memcpy((__force void *) to, from, n);
166 return 0;
167 }
168
169 return access_ok(VERIFY_WRITE, to, n) ?
170 buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
171 n;
172 }
173
174 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
175 {
176 char **to_ptr = arg, *to = *to_ptr;
177 int n;
178
179 strncpy(to, (void *) from, len);
180 n = strnlen(to, len);
181 *to_ptr += n;
182
183 if (n < len)
184 return 1;
185 return 0;
186 }
187
188 int strncpy_from_user(char *dst, const char __user *src, int count)
189 {
190 int n;
191 char *ptr = dst;
192
193 if (segment_eq(get_fs(), KERNEL_DS)) {
194 strncpy(dst, (__force void *) src, count);
195 return strnlen(dst, count);
196 }
197
198 if (!access_ok(VERIFY_READ, src, 1))
199 return -EFAULT;
200
201 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
202 &ptr);
203 if (n != 0)
204 return -EFAULT;
205 return strnlen(dst, count);
206 }
207
208 static int clear_chunk(unsigned long addr, int len, void *unused)
209 {
210 memset((void *) addr, 0, len);
211 return 0;
212 }
213
214 int __clear_user(void __user *mem, int len)
215 {
216 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
217 }
218
219 int clear_user(void __user *mem, int len)
220 {
221 if (segment_eq(get_fs(), KERNEL_DS)) {
222 memset((__force void*)mem, 0, len);
223 return 0;
224 }
225
226 return access_ok(VERIFY_WRITE, mem, len) ?
227 buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len;
228 }
229
230 static int strnlen_chunk(unsigned long str, int len, void *arg)
231 {
232 int *len_ptr = arg, n;
233
234 n = strnlen((void *) str, len);
235 *len_ptr += n;
236
237 if (n < len)
238 return 1;
239 return 0;
240 }
241
242 int strnlen_user(const void __user *str, int len)
243 {
244 int count = 0, n;
245
246 if (segment_eq(get_fs(), KERNEL_DS))
247 return strnlen((__force char*)str, len) + 1;
248
249 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
250 if (n == 0)
251 return count + 1;
252 return -EFAULT;
253 }
254
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