summaryrefslogtreecommitdiff
path: root/src/libsystemd-network/dhcp-identifier.c
blob: f33817ca7d070abab75795c39bd77300f7e912f3 (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
/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright (C) 2015 Tom Gundersen <teg@jklmen>

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include "libudev.h"
#include "sd-id128.h"

#include "dhcp-identifier.h"
#include "dhcp6-protocol.h"
#include "network-internal.h"
#include "siphash24.h"
#include "sparse-endian.h"
#include "udev-util.h"
#include "virt.h"

#define SYSTEMD_PEN 43793
#define HASH_KEY SD_ID128_MAKE(80,11,8c,c2,fe,4a,03,ee,3e,d6,0c,6f,36,39,14,09)

int dhcp_validate_duid_len(uint16_t duid_type, size_t duid_len) {
        struct duid d;

        assert_cc(sizeof(d.raw) >= MAX_DUID_LEN);
        if (duid_len > MAX_DUID_LEN)
                return -EINVAL;

        switch (duid_type) {
        case DUID_TYPE_LLT:
                if (duid_len <= sizeof(d.llt))
                        return -EINVAL;
                break;
        case DUID_TYPE_EN:
                if (duid_len != sizeof(d.en))
                        return -EINVAL;
                break;
        case DUID_TYPE_LL:
                if (duid_len <= sizeof(d.ll))
                        return -EINVAL;
                break;
        case DUID_TYPE_UUID:
                if (duid_len != sizeof(d.uuid))
                        return -EINVAL;
                break;
        default:
                /* accept unknown type in order to be forward compatible */
                break;
        }
        return 0;
}

int dhcp_identifier_set_duid_en(struct duid *duid, size_t *len) {
        sd_id128_t machine_id;
        uint64_t hash;
        int r;

        assert(duid);
        assert(len);

        r = sd_id128_get_machine(&machine_id);
        if (r < 0)
                return r;

        unaligned_write_be16(&duid->type, DUID_TYPE_EN);
        unaligned_write_be32(&duid->en.pen, SYSTEMD_PEN);

        *len = sizeof(duid->type) + sizeof(duid->en);

        /* a bit of snake-oil perhaps, but no need to expose the machine-id
           directly; duid->en.id might not be aligned, so we need to copy */
        hash = htole64(siphash24(&machine_id, sizeof(machine_id), HASH_KEY.bytes));
        memcpy(duid->en.id, &hash, sizeof(duid->en.id));

        return 0;
}

int dhcp_identifier_set_iaid(int ifindex, uint8_t *mac, size_t mac_len, void *_id) {
        /* name is a pointer to memory in the udev_device struct, so must
           have the same scope */
        _cleanup_udev_device_unref_ struct udev_device *device = NULL;
        const char *name = NULL;
        uint64_t id;

        if (detect_container() <= 0) {
                /* not in a container, udev will be around */
                _cleanup_udev_unref_ struct udev *udev;
                char ifindex_str[2 + DECIMAL_STR_MAX(int)];

                udev = udev_new();
                if (!udev)
                        return -ENOMEM;

                sprintf(ifindex_str, "n%d", ifindex);
                device = udev_device_new_from_device_id(udev, ifindex_str);
                if (device) {
                        if (udev_device_get_is_initialized(device) <= 0)
                                /* not yet ready */
                                return -EBUSY;

                        name = net_get_name(device);
                }
        }

        if (name)
                id = siphash24(name, strlen(name), HASH_KEY.bytes);
        else
                /* fall back to MAC address if no predictable name available */
                id = siphash24(mac, mac_len, HASH_KEY.bytes);

        id = htole64(id);

        /* fold into 32 bits */
        unaligned_write_be32(_id, (id & 0xffffffff) ^ (id >> 32));

        return 0;
}