summaryrefslogtreecommitdiffstats
path: root/net/core/iovec.c
blob: 86beeea61d7224abd80173f041525a941aef1a73 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
/*
 *	iovec manipulation routines.
 *
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 *	Fixes:
 *		Andrew Lunn	:	Errors in iovec copying.
 *		Pedro Roque	:	Added memcpy_fromiovecend and
 *					csum_..._fromiovecend.
 *		Andi Kleen	:	fixed error handling for 2.1
 *		Alexey Kuznetsov:	2.1 optimisations
 *		Andi Kleen	:	Fix csum*fromiovecend for IPv6.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/net.h>
#include <linux/in6.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>
#include <net/checksum.h>
#include <net/sock.h>

/*
 *	Verify iovec. The caller must ensure that the iovec is big enough
 *	to hold the message iovec.
 *
 *	Save time not doing access_ok. copy_*_user will make this work
 *	in any case.
 */

int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr_storage *address, int mode)
{
	struct iovec *res;
	int err;

	if (m->msg_name && m->msg_namelen) {
		if (mode == WRITE) {
			void __user *namep = (void __user __force *)m->msg_name;
			int err = move_addr_to_kernel(namep, m->msg_namelen,
						  address);
			if (err < 0)
				return err;
		}
		m->msg_name = address;
	} else {
		m->msg_name = NULL;
		m->msg_namelen = 0;
	}
	if (m->msg_iovlen > UIO_MAXIOV)
		return -EMSGSIZE;

	err = rw_copy_check_uvector(mode, (void __user __force *)m->msg_iov,
				    m->msg_iovlen, UIO_FASTIOV, iov, &res);
	if (err >= 0)
		m->msg_iov = res;
	else if (res != iov)
		kfree(res);
	return err;
}

/*
 *	And now for the all-in-one: copy and checksum from a user iovec
 *	directly to a datagram
 *	Calls to csum_partial but the last must be in 32 bit chunks
 *
 *	ip_build_xmit must ensure that when fragmenting only the last
 *	call to this function will be unaligned also.
 */
int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
				 int offset, unsigned int len, __wsum *csump)
{
	__wsum csum = *csump;
	int partial_cnt = 0, err = 0;

	/* Skip over the finished iovecs */
	while (offset >= iov->iov_len) {
		offset -= iov->iov_len;
		iov++;
	}

	while (len > 0) {
		u8 __user *base = iov->iov_base + offset;
		int copy = min_t(unsigned int, len, iov->iov_len - offset);

		offset = 0;

		/* There is a remnant from previous iov. */
		if (partial_cnt) {
			int par_len = 4 - partial_cnt;

			/* iov component is too short ... */
			if (par_len > copy) {
				if (copy_from_user(kdata, base, copy))
					goto out_fault;
				kdata += copy;
				base += copy;
				partial_cnt += copy;
				len -= copy;
				iov++;
				if (len)
					continue;
				*csump = csum_partial(kdata - partial_cnt,
							 partial_cnt, csum);
				goto out;
			}
			if (copy_from_user(kdata, base, par_len))
				goto out_fault;
			csum = csum_partial(kdata - partial_cnt, 4, csum);
			kdata += par_len;
			base  += par_len;
			copy  -= par_len;
			len   -= par_len;
			partial_cnt = 0;
		}

		if (len > copy) {
			partial_cnt = copy % 4;
			if (partial_cnt) {
				copy -= partial_cnt;
				if (copy_from_user(kdata + copy, base + copy,
						partial_cnt))
					goto out_fault;
			}
		}

		if (copy) {
			csum = csum_and_copy_from_user(base, kdata, copy,
							csum, &err);
			if (err)
				goto out;
		}
		len   -= copy + partial_cnt;
		kdata += copy + partial_cnt;
		iov++;
	}
	*csump = csum;
out:
	return err;

out_fault:
	err = -EFAULT;
	goto out;
}
EXPORT_SYMBOL(csum_partial_copy_fromiovecend);

unsigned long iov_pages(const struct iovec *iov, int offset,
			unsigned long nr_segs)
{
	unsigned long seg, base;
	int pages = 0, len, size;

	while (nr_segs && (offset >= iov->iov_len)) {
		offset -= iov->iov_len;
		++iov;
		--nr_segs;
	}

	for (seg = 0; seg < nr_segs; seg++) {
		base = (unsigned long)iov[seg].iov_base + offset;
		len = iov[seg].iov_len - offset;
		size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
		pages += size;
		offset = 0;
	}

	return pages;
}
EXPORT_SYMBOL(iov_pages);