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1 | /*-*- Mode: C; c-basic-offset: 8 -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <errno.h> | |
23 | #include <sys/socket.h> | |
24 | #include <net/if.h> | |
25 | #include <asm/types.h> | |
26 | #include <netinet/in.h> | |
27 | #include <string.h> | |
28 | #include <stdlib.h> | |
29 | #include <unistd.h> | |
30 | #include <linux/netlink.h> | |
31 | #include <linux/rtnetlink.h> | |
32 | ||
33 | #include "util.h" | |
34 | #include "macro.h" | |
35 | #include "loopback-setup.h" | |
36 | ||
37 | enum { | |
38 | REQUEST_NONE = 0, | |
39 | REQUEST_ADDRESS_IPV4 = 1, | |
40 | REQUEST_ADDRESS_IPV6 = 2, | |
41 | REQUEST_FLAGS = 4, | |
42 | REQUEST_ALL = 7 | |
43 | }; | |
44 | ||
45 | #define NLMSG_TAIL(nmsg) \ | |
46 | ((struct rtattr *) (((uint8_t*) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len))) | |
47 | ||
48 | static int add_rtattr(struct nlmsghdr *n, size_t max_length, int type, const void *data, size_t data_length) { | |
49 | size_t length; | |
50 | struct rtattr *rta; | |
51 | ||
52 | length = RTA_LENGTH(data_length); | |
53 | ||
54 | if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length) > max_length) | |
55 | return -E2BIG; | |
56 | ||
57 | rta = NLMSG_TAIL(n); | |
58 | rta->rta_type = type; | |
59 | rta->rta_len = length; | |
60 | memcpy(RTA_DATA(rta), data, data_length); | |
61 | n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length); | |
62 | ||
63 | return 0; | |
64 | } | |
65 | ||
66 | static ssize_t sendto_loop(int fd, const void *buf, size_t buf_len, int flags, const struct sockaddr *sa, socklen_t sa_len) { | |
67 | ||
68 | for (;;) { | |
69 | ssize_t l; | |
70 | ||
71 | if ((l = sendto(fd, buf, buf_len, flags, sa, sa_len)) >= 0) | |
72 | return l; | |
73 | ||
74 | if (errno != EINTR) | |
75 | return -errno; | |
76 | } | |
77 | } | |
78 | ||
79 | static ssize_t recvfrom_loop(int fd, void *buf, size_t buf_len, int flags, struct sockaddr *sa, socklen_t *sa_len) { | |
80 | ||
81 | for (;;) { | |
82 | ssize_t l; | |
83 | ||
84 | if ((l = recvfrom(fd, buf, buf_len, flags, sa, sa_len)) >= 0) | |
85 | return l; | |
86 | ||
87 | if (errno != EINTR) | |
88 | return -errno; | |
89 | } | |
90 | } | |
91 | ||
92 | static int add_adresses(int fd, int if_loopback) { | |
93 | union { | |
94 | struct sockaddr sa; | |
95 | struct sockaddr_nl nl; | |
96 | } sa; | |
97 | union { | |
98 | struct nlmsghdr header; | |
99 | uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + | |
100 | NLMSG_ALIGN(sizeof(struct ifaddrmsg)) + | |
101 | RTA_LENGTH(sizeof(struct in6_addr))]; | |
102 | } request; | |
103 | ||
104 | struct ifaddrmsg *ifaddrmsg; | |
105 | uint32_t ipv4_address = htonl(INADDR_LOOPBACK); | |
106 | int r; | |
107 | ||
108 | zero(request); | |
109 | ||
110 | request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)); | |
111 | request.header.nlmsg_type = RTM_NEWADDR; | |
112 | request.header.nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_ACK; | |
113 | request.header.nlmsg_seq = REQUEST_ADDRESS_IPV4; | |
114 | ||
115 | ifaddrmsg = NLMSG_DATA(&request.header); | |
116 | ifaddrmsg->ifa_family = AF_INET; | |
117 | ifaddrmsg->ifa_prefixlen = 8; | |
118 | ifaddrmsg->ifa_flags = IFA_F_PERMANENT; | |
119 | ifaddrmsg->ifa_scope = RT_SCOPE_HOST; | |
120 | ifaddrmsg->ifa_index = if_loopback; | |
121 | ||
122 | if ((r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &ipv4_address, sizeof(ipv4_address))) < 0) | |
123 | return r; | |
124 | ||
125 | zero(sa); | |
126 | sa.nl.nl_family = AF_NETLINK; | |
127 | ||
128 | if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0) | |
129 | return -errno; | |
130 | ||
131 | request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)); | |
132 | request.header.nlmsg_seq = REQUEST_ADDRESS_IPV6; | |
133 | ||
134 | ifaddrmsg->ifa_family = AF_INET6; | |
135 | ifaddrmsg->ifa_prefixlen = 128; | |
136 | ||
137 | if ((r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &in6addr_loopback, sizeof(in6addr_loopback))) < 0) | |
138 | return r; | |
139 | ||
140 | if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0) | |
141 | return -errno; | |
142 | ||
143 | return 0; | |
144 | } | |
145 | ||
146 | static int start_interface(int fd, int if_loopback) { | |
147 | union { | |
148 | struct sockaddr sa; | |
149 | struct sockaddr_nl nl; | |
150 | } sa; | |
151 | union { | |
152 | struct nlmsghdr header; | |
153 | uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + | |
154 | NLMSG_ALIGN(sizeof(struct ifinfomsg))]; | |
155 | } request; | |
156 | ||
157 | struct ifinfomsg *ifinfomsg; | |
158 | ||
159 | zero(request); | |
160 | ||
161 | request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)); | |
162 | request.header.nlmsg_type = RTM_NEWLINK; | |
163 | request.header.nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK; | |
164 | request.header.nlmsg_seq = REQUEST_FLAGS; | |
165 | ||
166 | ifinfomsg = NLMSG_DATA(&request.header); | |
167 | ifinfomsg->ifi_family = AF_UNSPEC; | |
168 | ifinfomsg->ifi_index = if_loopback; | |
169 | ifinfomsg->ifi_flags = IFF_UP; | |
170 | ifinfomsg->ifi_change = IFF_UP; | |
171 | ||
172 | zero(sa); | |
173 | sa.nl.nl_family = AF_NETLINK; | |
174 | ||
175 | if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0) | |
176 | return -errno; | |
177 | ||
178 | return 0; | |
179 | } | |
180 | ||
181 | static int read_response(int fd) { | |
182 | union { | |
183 | struct sockaddr sa; | |
184 | struct sockaddr_nl nl; | |
185 | } sa; | |
186 | union { | |
187 | struct nlmsghdr header; | |
188 | uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + | |
189 | NLMSG_ALIGN(sizeof(struct nlmsgerr))]; | |
190 | } response; | |
191 | ||
192 | ssize_t l; | |
193 | socklen_t sa_len = sizeof(sa); | |
194 | struct nlmsgerr *nlmsgerr; | |
195 | ||
196 | if ((l = recvfrom_loop(fd, &response, sizeof(response), 0, &sa.sa, &sa_len)) < 0) | |
197 | return -errno; | |
198 | ||
199 | if (sa_len != sizeof(sa.nl) || | |
200 | sa.nl.nl_family != AF_NETLINK) | |
201 | return -EIO; | |
202 | ||
203 | if (sa.nl.nl_pid != 0) | |
204 | return 0; | |
205 | ||
206 | if ((size_t) l < sizeof(struct nlmsghdr)) | |
207 | return -EIO; | |
208 | ||
209 | if (response.header.nlmsg_type != NLMSG_ERROR || | |
210 | (pid_t) response.header.nlmsg_pid != getpid() || | |
211 | response.header.nlmsg_seq >= REQUEST_ALL) | |
212 | return 0; | |
213 | ||
214 | if ((size_t) l < NLMSG_LENGTH(sizeof(struct nlmsgerr)) || | |
215 | response.header.nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) | |
216 | return -EIO; | |
217 | ||
218 | nlmsgerr = NLMSG_DATA(&response.header); | |
219 | ||
220 | if (nlmsgerr->error < 0 && nlmsgerr->error != -EEXIST) | |
221 | return nlmsgerr->error; | |
222 | ||
223 | return response.header.nlmsg_seq; | |
224 | } | |
225 | ||
226 | int loopback_setup(void) { | |
227 | int r, if_loopback; | |
228 | union { | |
229 | struct sockaddr sa; | |
230 | struct sockaddr_nl nl; | |
231 | struct sockaddr_storage storage; | |
232 | } sa; | |
233 | int requests = REQUEST_NONE; | |
234 | ||
235 | int fd; | |
236 | ||
237 | errno = 0; | |
238 | if ((if_loopback = (int) if_nametoindex("lo")) <= 0) | |
239 | return errno ? -errno : -ENODEV; | |
240 | ||
241 | if ((fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) < 0) | |
242 | return -errno; | |
243 | ||
244 | zero(sa); | |
245 | sa.nl.nl_family = AF_NETLINK; | |
246 | ||
247 | if (bind(fd, &sa.sa, sizeof(sa)) < 0) { | |
248 | r = -errno; | |
249 | goto finish; | |
250 | } | |
251 | ||
252 | if ((r = add_adresses(fd, if_loopback)) < 0) | |
253 | goto finish; | |
254 | ||
255 | if ((r = start_interface(fd, if_loopback)) < 0) | |
256 | goto finish; | |
257 | ||
258 | do { | |
259 | if ((r = read_response(fd)) < 0) | |
260 | goto finish; | |
261 | ||
262 | requests |= r; | |
263 | ||
264 | } while (requests != REQUEST_ALL); | |
265 | ||
266 | r = 0; | |
267 | ||
268 | finish: | |
269 | if (r < 0) | |
270 | log_error("Failed to configure loopback device: %s", strerror(-r)); | |
271 | ||
272 | if (fd >= 0) | |
273 | close_nointr_nofail(fd); | |
274 | ||
275 | return r; | |
276 | } |