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/net.h>
24 #include <linux/in6.h>
25 #include <asm/uaccess.h>
26 #include <asm/byteorder.h>
27 #include <net/checksum.h>
28 #include <net/sock.h>
29
30 /*
31 * Verify iovec. The caller must ensure that the iovec is big enough
32 * to hold the message iovec.
33 *
34 * Save time not doing access_ok. copy_*_user will make this work
35 * in any case.
36 */
37
verify_iovec(struct msghdr * m,struct iovec * iov,struct sockaddr_storage * address,int mode)38 int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode)
39 {
40 int size, ct, err;
41
42 if (m->msg_name && m->msg_namelen) {
43 if (mode == VERIFY_READ) {
44 void __user *namep;
45 namep = (void __user __force *) m->msg_name;
46 err = move_addr_to_kernel(namep, m->msg_namelen,
47 address);
48 if (err < 0)
49 return err;
50 }
51 m->msg_name = address;
52 } else {
53 m->msg_name = NULL;
54 m->msg_namelen = 0;
55 }
56
57 size = m->msg_iovlen * sizeof(struct iovec);
58 if (copy_from_user(iov, (void __user __force *) m->msg_iov, size))
59 return -EFAULT;
60
61 m->msg_iov = iov;
62 err = 0;
63
64 for (ct = 0; ct < m->msg_iovlen; ct++) {
65 size_t len = iov[ct].iov_len;
66
67 if (len > INT_MAX - err) {
68 len = INT_MAX - err;
69 iov[ct].iov_len = len;
70 }
71 err += len;
72 }
73
74 return err;
75 }
76
77 /*
78 * And now for the all-in-one: copy and checksum from a user iovec
79 * directly to a datagram
80 * Calls to csum_partial but the last must be in 32 bit chunks
81 *
82 * ip_build_xmit must ensure that when fragmenting only the last
83 * call to this function will be unaligned also.
84 */
csum_partial_copy_fromiovecend(unsigned char * kdata,struct iovec * iov,int offset,unsigned int len,__wsum * csump)85 int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
86 int offset, unsigned int len, __wsum *csump)
87 {
88 __wsum csum = *csump;
89 int partial_cnt = 0, err = 0;
90
91 /* Skip over the finished iovecs */
92 while (offset >= iov->iov_len) {
93 offset -= iov->iov_len;
94 iov++;
95 }
96
97 while (len > 0) {
98 u8 __user *base = iov->iov_base + offset;
99 int copy = min_t(unsigned int, len, iov->iov_len - offset);
100
101 offset = 0;
102
103 /* There is a remnant from previous iov. */
104 if (partial_cnt) {
105 int par_len = 4 - partial_cnt;
106
107 /* iov component is too short ... */
108 if (par_len > copy) {
109 if (copy_from_user(kdata, base, copy))
110 goto out_fault;
111 kdata += copy;
112 base += copy;
113 partial_cnt += copy;
114 len -= copy;
115 iov++;
116 if (len)
117 continue;
118 *csump = csum_partial(kdata - partial_cnt,
119 partial_cnt, csum);
120 goto out;
121 }
122 if (copy_from_user(kdata, base, par_len))
123 goto out_fault;
124 csum = csum_partial(kdata - partial_cnt, 4, csum);
125 kdata += par_len;
126 base += par_len;
127 copy -= par_len;
128 len -= par_len;
129 partial_cnt = 0;
130 }
131
132 if (len > copy) {
133 partial_cnt = copy % 4;
134 if (partial_cnt) {
135 copy -= partial_cnt;
136 if (copy_from_user(kdata + copy, base + copy,
137 partial_cnt))
138 goto out_fault;
139 }
140 }
141
142 if (copy) {
143 csum = csum_and_copy_from_user(base, kdata, copy,
144 csum, &err);
145 if (err)
146 goto out;
147 }
148 len -= copy + partial_cnt;
149 kdata += copy + partial_cnt;
150 iov++;
151 }
152 *csump = csum;
153 out:
154 return err;
155
156 out_fault:
157 err = -EFAULT;
158 goto out;
159 }
160 EXPORT_SYMBOL(csum_partial_copy_fromiovecend);
161
iov_pages(const struct iovec * iov,int offset,unsigned long nr_segs)162 unsigned long iov_pages(const struct iovec *iov, int offset,
163 unsigned long nr_segs)
164 {
165 unsigned long seg, base;
166 int pages = 0, len, size;
167
168 while (nr_segs && (offset >= iov->iov_len)) {
169 offset -= iov->iov_len;
170 ++iov;
171 --nr_segs;
172 }
173
174 for (seg = 0; seg < nr_segs; seg++) {
175 base = (unsigned long)iov[seg].iov_base + offset;
176 len = iov[seg].iov_len - offset;
177 size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
178 pages += size;
179 offset = 0;
180 }
181
182 return pages;
183 }
184 EXPORT_SYMBOL(iov_pages);
185