1 /*
2 * iovec manipulation routines.
3 *
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * Fixes:
11 * Andrew Lunn : Errors in iovec copying.
12 * Pedro Roque : Added memcpy_fromiovecend and
13 * csum_..._fromiovecend.
14 * Andi Kleen : fixed error handling for 2.1
15 * Alexey Kuznetsov: 2.1 optimisations
16 * Andi Kleen : Fix csum*fromiovecend for IPv6.
17 */
18
19 #include <linux/errno.h>
20 #include <linux/module.h>
21 #include <linux/kernel.h>
22 #include <linux/mm.h>
23 #include <linux/slab.h>
24 #include <linux/net.h>
25 #include <linux/in6.h>
26 #include <asm/uaccess.h>
27 #include <asm/byteorder.h>
28 #include <net/checksum.h>
29 #include <net/sock.h>
30
31 /*
32 * Verify iovec. The caller must ensure that the iovec is big enough
33 * to hold the message iovec.
34 *
35 * Save time not doing access_ok. copy_*_user will make this work
36 * in any case.
37 */
38
39 int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode)
40 {
41 int size, err, ct;
42
43 if (m->msg_namelen) {
44 if (mode == VERIFY_READ) {
45 err = move_addr_to_kernel(m->msg_name, m->msg_namelen,
46 address);
47 if (err < 0)
48 return err;
49 }
50 m->msg_name = address;
51 } else {
52 m->msg_name = NULL;
53 }
54
55 size = m->msg_iovlen * sizeof(struct iovec);
56 if (copy_from_user(iov, m->msg_iov, size))
57 return -EFAULT;
58
59 m->msg_iov = iov;
60 err = 0;
61
62 for (ct = 0; ct < m->msg_iovlen; ct++) {
63 err += iov[ct].iov_len;
64 /*
65 * Goal is not to verify user data, but to prevent returning
66 * negative value, which is interpreted as errno.
67 * Overflow is still possible, but it is harmless.
68 */
69 if (err < 0)
70 return -EMSGSIZE;
71 }
72
73 return err;
74 }
75
76 /*
77 * Copy kernel to iovec. Returns -EFAULT on error.
78 *
79 * Note: this modifies the original iovec.
80 */
81
82 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len)
83 {
84 while (len > 0) {
85 if (iov->iov_len) {
86 int copy = min_t(unsigned int, iov->iov_len, len);
87 if (copy_to_user(iov->iov_base, kdata, copy))
88 return -EFAULT;
89 kdata += copy;
90 len -= copy;
91 iov->iov_len -= copy;
92 iov->iov_base += copy;
93 }
94 iov++;
95 }
96
97 return 0;
98 }
99
100 /*
101 * Copy kernel to iovec. Returns -EFAULT on error.
102 */
103
104 int memcpy_toiovecend(const struct iovec *iov, unsigned char *kdata,
105 int offset, int len)
106 {
107 int copy;
108 for (; len > 0; ++iov) {
109 /* Skip over the finished iovecs */
110 if (unlikely(offset >= iov->iov_len)) {
111 offset -= iov->iov_len;
112 continue;
113 }
114 copy = min_t(unsigned int, iov->iov_len - offset, len);
115 if (copy_to_user(iov->iov_base + offset, kdata, copy))
116 return -EFAULT;
117 offset = 0;
118 kdata += copy;
119 len -= copy;
120 }
121
122 return 0;
123 }
124
125 /*
126 * Copy iovec to kernel. Returns -EFAULT on error.
127 *
128 * Note: this modifies the original iovec.
129 */
130
131 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len)
132 {
133 while (len > 0) {
134 if (iov->iov_len) {
135 int copy = min_t(unsigned int, len, iov->iov_len);
136 if (copy_from_user(kdata, iov->iov_base, copy))
137 return -EFAULT;
138 len -= copy;
139 kdata += copy;
140 iov->iov_base += copy;
141 iov->iov_len -= copy;
142 }
143 iov++;
144 }
145
146 return 0;
147 }
148
149 /*
150 * Copy iovec from kernel. Returns -EFAULT on error.
151 */
152
153 int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
154 int offset, int len)
155 {
156 /* Skip over the finished iovecs */
157 while (offset >= iov->iov_len) {
158 offset -= iov->iov_len;
159 iov++;
160 }
161
162 while (len > 0) {
163 u8 __user *base = iov->iov_base + offset;
164 int copy = min_t(unsigned int, len, iov->iov_len - offset);
165
166 offset = 0;
167 if (copy_from_user(kdata, base, copy))
168 return -EFAULT;
169 len -= copy;
170 kdata += copy;
171 iov++;
172 }
173
174 return 0;
175 }
176
177 /*
178 * And now for the all-in-one: copy and checksum from a user iovec
179 * directly to a datagram
180 * Calls to csum_partial but the last must be in 32 bit chunks
181 *
182 * ip_build_xmit must ensure that when fragmenting only the last
183 * call to this function will be unaligned also.
184 */
185 int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
186 int offset, unsigned int len, __wsum *csump)
187 {
188 __wsum csum = *csump;
189 int partial_cnt = 0, err = 0;
190
191 /* Skip over the finished iovecs */
192 while (offset >= iov->iov_len) {
193 offset -= iov->iov_len;
194 iov++;
195 }
196
197 while (len > 0) {
198 u8 __user *base = iov->iov_base + offset;
199 int copy = min_t(unsigned int, len, iov->iov_len - offset);
200
201 offset = 0;
202
203 /* There is a remnant from previous iov. */
204 if (partial_cnt) {
205 int par_len = 4 - partial_cnt;
206
207 /* iov component is too short ... */
208 if (par_len > copy) {
209 if (copy_from_user(kdata, base, copy))
210 goto out_fault;
211 kdata += copy;
212 base += copy;
213 partial_cnt += copy;
214 len -= copy;
215 iov++;
216 if (len)
217 continue;
218 *csump = csum_partial(kdata - partial_cnt,
219 partial_cnt, csum);
220 goto out;
221 }
222 if (copy_from_user(kdata, base, par_len))
223 goto out_fault;
224 csum = csum_partial(kdata - partial_cnt, 4, csum);
225 kdata += par_len;
226 base += par_len;
227 copy -= par_len;
228 len -= par_len;
229 partial_cnt = 0;
230 }
231
232 if (len > copy) {
233 partial_cnt = copy % 4;
234 if (partial_cnt) {
235 copy -= partial_cnt;
236 if (copy_from_user(kdata + copy, base + copy,
237 partial_cnt))
238 goto out_fault;
239 }
240 }
241
242 if (copy) {
243 csum = csum_and_copy_from_user(base, kdata, copy,
244 csum, &err);
245 if (err)
246 goto out;
247 }
248 len -= copy + partial_cnt;
249 kdata += copy + partial_cnt;
250 iov++;
251 }
252 *csump = csum;
253 out:
254 return err;
255
256 out_fault:
257 err = -EFAULT;
258 goto out;
259 }
260
261 EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
262 EXPORT_SYMBOL(memcpy_fromiovec);
263 EXPORT_SYMBOL(memcpy_fromiovecend);
264 EXPORT_SYMBOL(memcpy_toiovec);
265 EXPORT_SYMBOL(memcpy_toiovecend);
266
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