/arch/um/kernel/skas/uaccess.c

  1/*
  2 * Copyright (C) 2002 - 2003 Jeff Dike (jdike@addtoit.com)
  3 * Licensed under the GPL
  4 */
  5
  6#include "linux/stddef.h"
  7#include "linux/kernel.h"
  8#include "linux/string.h"
  9#include "linux/fs.h"
 10#include "linux/highmem.h"
 11#include "asm/page.h"
 12#include "asm/pgtable.h"
 13#include "asm/uaccess.h"
 14#include "kern_util.h"
 15#include "user_util.h"
 16
 17extern void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
 18			     pte_t *pte_out);
 19
 20static unsigned long maybe_map(unsigned long virt, int is_write)
 21{
 22	pte_t pte;
 23	int err;
 24
 25	void *phys = um_virt_to_phys(current, virt, &pte);
 26	int dummy_code;
 27
 28	if(IS_ERR(phys) || (is_write && !pte_write(pte))){
 29		err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
 30		if(err)
 31			return(0);
 32		phys = um_virt_to_phys(current, virt, NULL);
 33	}
 34	return((unsigned long) phys);
 35}
 36
 37static int do_op(unsigned long addr, int len, int is_write,
 38		 int (*op)(unsigned long addr, int len, void *arg), void *arg)
 39{
 40	struct page *page;
 41	int n;
 42
 43	addr = maybe_map(addr, is_write);
 44	if(addr == -1)
 45		return(-1);
 46
 47	page = phys_to_page(addr);
 48	addr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
 49	n = (*op)(addr, len, arg);
 50	kunmap(page);
 51
 52	return(n);
 53}
 54
 55static void do_buffer_op(void *jmpbuf, void *arg_ptr)
 56{
 57	va_list args;
 58	unsigned long addr;
 59	int len, is_write, size, remain, n;
 60	int (*op)(unsigned long, int, void *);
 61	void *arg;
 62	int *res;
 63
 64	/* Some old gccs recognize __va_copy, but not va_copy */
 65	__va_copy(args, *(va_list *)arg_ptr);
 66	addr = va_arg(args, unsigned long);
 67	len = va_arg(args, int);
 68	is_write = va_arg(args, int);
 69	op = va_arg(args, void *);
 70	arg = va_arg(args, void *);
 71	res = va_arg(args, int *);
 72	va_end(args);
 73	size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
 74	remain = len;
 75
 76	current->thread.fault_catcher = jmpbuf;
 77	n = do_op(addr, size, is_write, op, arg);
 78	if(n != 0){
 79		*res = (n < 0 ? remain : 0);
 80		goto out;
 81	}
 82
 83	addr += size;
 84	remain -= size;
 85	if(remain == 0){
 86		*res = 0;
 87		goto out;
 88	}
 89
 90	while(addr < ((addr + remain) & PAGE_MASK)){
 91		n = do_op(addr, PAGE_SIZE, is_write, op, arg);
 92		if(n != 0){
 93			*res = (n < 0 ? remain : 0);
 94			goto out;
 95		}
 96
 97		addr += PAGE_SIZE;
 98		remain -= PAGE_SIZE;
 99	}
100	if(remain == 0){
101		*res = 0;
102		goto out;
103	}
104
105	n = do_op(addr, remain, is_write, op, arg);
106	if(n != 0)
107		*res = (n < 0 ? remain : 0);
108	else *res = 0;
109 out:
110	current->thread.fault_catcher = NULL;
111}
112
113static int buffer_op(unsigned long addr, int len, int is_write,
114		     int (*op)(unsigned long addr, int len, void *arg),
115		     void *arg)
116{
117	int faulted, res;
118
119	faulted = setjmp_wrapper(do_buffer_op, addr, len, is_write, op, arg,
120				 &res);
121	if(!faulted)
122		return(res);
123
124	return(addr + len - (unsigned long) current->thread.fault_addr);
125}
126
127static int copy_chunk_from_user(unsigned long from, int len, void *arg)
128{
129	unsigned long *to_ptr = arg, to = *to_ptr;
130
131	memcpy((void *) to, (void *) from, len);
132	*to_ptr += len;
133	return(0);
134}
135
136int copy_from_user_skas(void *to, const void __user *from, int n)
137{
138	if(segment_eq(get_fs(), KERNEL_DS)){
139		memcpy(to, (__force void*)from, n);
140		return(0);
141	}
142
143	return(access_ok_skas(VERIFY_READ, from, n) ?
144	       buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
145	       n);
146}
147
148static int copy_chunk_to_user(unsigned long to, int len, void *arg)
149{
150	unsigned long *from_ptr = arg, from = *from_ptr;
151
152	memcpy((void *) to, (void *) from, len);
153	*from_ptr += len;
154	return(0);
155}
156
157int copy_to_user_skas(void __user *to, const void *from, int n)
158{
159	if(segment_eq(get_fs(), KERNEL_DS)){
160		memcpy((__force void*)to, from, n);
161		return(0);
162	}
163
164	return(access_ok_skas(VERIFY_WRITE, to, n) ?
165	       buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
166	       n);
167}
168
169static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
170{
171	char **to_ptr = arg, *to = *to_ptr;
172	int n;
173
174	strncpy(to, (void *) from, len);
175	n = strnlen(to, len);
176	*to_ptr += n;
177
178	if(n < len)
179	        return(1);
180	return(0);
181}
182
183int strncpy_from_user_skas(char *dst, const char __user *src, int count)
184{
185	int n;
186	char *ptr = dst;
187
188	if(segment_eq(get_fs(), KERNEL_DS)){
189		strncpy(dst, (__force void*)src, count);
190		return(strnlen(dst, count));
191	}
192
193	if(!access_ok_skas(VERIFY_READ, src, 1))
194		return(-EFAULT);
195
196	n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
197		      &ptr);
198	if(n != 0)
199		return(-EFAULT);
200	return(strnlen(dst, count));
201}
202
203static int clear_chunk(unsigned long addr, int len, void *unused)
204{
205	memset((void *) addr, 0, len);
206	return(0);
207}
208
209int __clear_user_skas(void __user *mem, int len)
210{
211	return(buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL));
212}
213
214int clear_user_skas(void __user *mem, int len)
215{
216	if(segment_eq(get_fs(), KERNEL_DS)){
217		memset((__force void*)mem, 0, len);
218		return(0);
219	}
220
221	return(access_ok_skas(VERIFY_WRITE, mem, len) ?
222	       buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len);
223}
224
225static int strnlen_chunk(unsigned long str, int len, void *arg)
226{
227	int *len_ptr = arg, n;
228
229	n = strnlen((void *) str, len);
230	*len_ptr += n;
231
232	if(n < len)
233		return(1);
234	return(0);
235}
236
237int strnlen_user_skas(const void __user *str, int len)
238{
239	int count = 0, n;
240
241	if(segment_eq(get_fs(), KERNEL_DS))
242		return(strnlen((__force char*)str, len) + 1);
243
244	n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
245	if(n == 0)
246		return(count + 1);
247	return(-EFAULT);
248}
249
250/*
251 * Overrides for Emacs so that we follow Linus's tabbing style.
252 * Emacs will notice this stuff at the end of the file and automatically
253 * adjust the settings for this buffer only.  This must remain at the end
254 * of the file.
255 * ---------------------------------------------------------------------------
256 * Local variables:
257 * c-file-style: "linux"
258 * End:
259 */