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d6c9574f | 1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
af5bc85d LP |
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 | |
5430f7f2 LP |
9 | under the terms of the GNU Lesser General Public License as published by |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
af5bc85d LP |
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 | |
5430f7f2 | 16 | Lesser General Public License for more details. |
af5bc85d | 17 | |
5430f7f2 | 18 | You should have received a copy of the GNU Lesser General Public License |
af5bc85d LP |
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" | |
5bfcc1c6 | 36 | #include "socket-util.h" |
af5bc85d LP |
37 | |
38 | #define NLMSG_TAIL(nmsg) \ | |
39 | ((struct rtattr *) (((uint8_t*) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len))) | |
40 | ||
41 | static int add_rtattr(struct nlmsghdr *n, size_t max_length, int type, const void *data, size_t data_length) { | |
42 | size_t length; | |
43 | struct rtattr *rta; | |
44 | ||
45 | length = RTA_LENGTH(data_length); | |
46 | ||
47 | if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length) > max_length) | |
48 | return -E2BIG; | |
49 | ||
50 | rta = NLMSG_TAIL(n); | |
51 | rta->rta_type = type; | |
52 | rta->rta_len = length; | |
53 | memcpy(RTA_DATA(rta), data, data_length); | |
54 | n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length); | |
55 | ||
56 | return 0; | |
57 | } | |
58 | ||
59 | static ssize_t sendto_loop(int fd, const void *buf, size_t buf_len, int flags, const struct sockaddr *sa, socklen_t sa_len) { | |
60 | ||
61 | for (;;) { | |
62 | ssize_t l; | |
63 | ||
2c3ff76e LP |
64 | l = sendto(fd, buf, buf_len, flags, sa, sa_len); |
65 | if (l >= 0) | |
af5bc85d LP |
66 | return l; |
67 | ||
68 | if (errno != EINTR) | |
69 | return -errno; | |
70 | } | |
71 | } | |
72 | ||
73 | static ssize_t recvfrom_loop(int fd, void *buf, size_t buf_len, int flags, struct sockaddr *sa, socklen_t *sa_len) { | |
74 | ||
75 | for (;;) { | |
76 | ssize_t l; | |
77 | ||
2c3ff76e LP |
78 | l = recvfrom(fd, buf, buf_len, flags, sa, sa_len); |
79 | if (l >= 0) | |
af5bc85d LP |
80 | return l; |
81 | ||
82 | if (errno != EINTR) | |
83 | return -errno; | |
84 | } | |
85 | } | |
86 | ||
5bfcc1c6 | 87 | static int add_adresses(int fd, int if_loopback, unsigned *requests) { |
af5bc85d LP |
88 | union { |
89 | struct sockaddr sa; | |
90 | struct sockaddr_nl nl; | |
91 | } sa; | |
92 | union { | |
93 | struct nlmsghdr header; | |
94 | uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + | |
95 | NLMSG_ALIGN(sizeof(struct ifaddrmsg)) + | |
96 | RTA_LENGTH(sizeof(struct in6_addr))]; | |
97 | } request; | |
98 | ||
99 | struct ifaddrmsg *ifaddrmsg; | |
100 | uint32_t ipv4_address = htonl(INADDR_LOOPBACK); | |
101 | int r; | |
102 | ||
103 | zero(request); | |
104 | ||
105 | request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)); | |
106 | request.header.nlmsg_type = RTM_NEWADDR; | |
107 | request.header.nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_ACK; | |
5bfcc1c6 | 108 | request.header.nlmsg_seq = *requests + 1; |
af5bc85d LP |
109 | |
110 | ifaddrmsg = NLMSG_DATA(&request.header); | |
111 | ifaddrmsg->ifa_family = AF_INET; | |
112 | ifaddrmsg->ifa_prefixlen = 8; | |
113 | ifaddrmsg->ifa_flags = IFA_F_PERMANENT; | |
114 | ifaddrmsg->ifa_scope = RT_SCOPE_HOST; | |
115 | ifaddrmsg->ifa_index = if_loopback; | |
116 | ||
2c3ff76e LP |
117 | r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &ipv4_address, sizeof(ipv4_address)); |
118 | if (r < 0) | |
af5bc85d LP |
119 | return r; |
120 | ||
121 | zero(sa); | |
122 | sa.nl.nl_family = AF_NETLINK; | |
123 | ||
124 | if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0) | |
125 | return -errno; | |
5bfcc1c6 FF |
126 | (*requests)++; |
127 | ||
128 | if (!socket_ipv6_is_supported()) | |
129 | return 0; | |
af5bc85d LP |
130 | |
131 | request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)); | |
5bfcc1c6 | 132 | request.header.nlmsg_seq = *requests + 1; |
af5bc85d LP |
133 | |
134 | ifaddrmsg->ifa_family = AF_INET6; | |
135 | ifaddrmsg->ifa_prefixlen = 128; | |
136 | ||
2c3ff76e LP |
137 | r = add_rtattr(&request.header, sizeof(request), IFA_LOCAL, &in6addr_loopback, sizeof(in6addr_loopback)); |
138 | if (r < 0) | |
af5bc85d LP |
139 | return r; |
140 | ||
141 | if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0) | |
142 | return -errno; | |
5bfcc1c6 | 143 | (*requests)++; |
af5bc85d LP |
144 | |
145 | return 0; | |
146 | } | |
147 | ||
5bfcc1c6 | 148 | static int start_interface(int fd, int if_loopback, unsigned *requests) { |
af5bc85d LP |
149 | union { |
150 | struct sockaddr sa; | |
151 | struct sockaddr_nl nl; | |
152 | } sa; | |
153 | union { | |
154 | struct nlmsghdr header; | |
155 | uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + | |
156 | NLMSG_ALIGN(sizeof(struct ifinfomsg))]; | |
157 | } request; | |
158 | ||
159 | struct ifinfomsg *ifinfomsg; | |
160 | ||
161 | zero(request); | |
162 | ||
163 | request.header.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)); | |
164 | request.header.nlmsg_type = RTM_NEWLINK; | |
165 | request.header.nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK; | |
5bfcc1c6 | 166 | request.header.nlmsg_seq = *requests + 1; |
af5bc85d LP |
167 | |
168 | ifinfomsg = NLMSG_DATA(&request.header); | |
169 | ifinfomsg->ifi_family = AF_UNSPEC; | |
170 | ifinfomsg->ifi_index = if_loopback; | |
171 | ifinfomsg->ifi_flags = IFF_UP; | |
172 | ifinfomsg->ifi_change = IFF_UP; | |
173 | ||
174 | zero(sa); | |
175 | sa.nl.nl_family = AF_NETLINK; | |
176 | ||
177 | if (sendto_loop(fd, &request, request.header.nlmsg_len, 0, &sa.sa, sizeof(sa)) < 0) | |
178 | return -errno; | |
179 | ||
5bfcc1c6 FF |
180 | (*requests)++; |
181 | ||
af5bc85d LP |
182 | return 0; |
183 | } | |
184 | ||
5bfcc1c6 | 185 | static int read_response(int fd, unsigned requests_max) { |
af5bc85d LP |
186 | union { |
187 | struct sockaddr sa; | |
188 | struct sockaddr_nl nl; | |
189 | } sa; | |
190 | union { | |
191 | struct nlmsghdr header; | |
192 | uint8_t buf[NLMSG_ALIGN(sizeof(struct nlmsghdr)) + | |
193 | NLMSG_ALIGN(sizeof(struct nlmsgerr))]; | |
194 | } response; | |
195 | ||
196 | ssize_t l; | |
197 | socklen_t sa_len = sizeof(sa); | |
198 | struct nlmsgerr *nlmsgerr; | |
199 | ||
2c3ff76e LP |
200 | l = recvfrom_loop(fd, &response, sizeof(response), 0, &sa.sa, &sa_len); |
201 | if (l < 0) | |
af5bc85d LP |
202 | return -errno; |
203 | ||
204 | if (sa_len != sizeof(sa.nl) || | |
205 | sa.nl.nl_family != AF_NETLINK) | |
206 | return -EIO; | |
207 | ||
208 | if (sa.nl.nl_pid != 0) | |
209 | return 0; | |
210 | ||
211 | if ((size_t) l < sizeof(struct nlmsghdr)) | |
212 | return -EIO; | |
213 | ||
214 | if (response.header.nlmsg_type != NLMSG_ERROR || | |
215 | (pid_t) response.header.nlmsg_pid != getpid() || | |
5bfcc1c6 | 216 | response.header.nlmsg_seq >= requests_max) |
af5bc85d LP |
217 | return 0; |
218 | ||
219 | if ((size_t) l < NLMSG_LENGTH(sizeof(struct nlmsgerr)) || | |
220 | response.header.nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr))) | |
221 | return -EIO; | |
222 | ||
223 | nlmsgerr = NLMSG_DATA(&response.header); | |
224 | ||
2c3ff76e | 225 | if (nlmsgerr->error < 0 && nlmsgerr->error != -EEXIST) |
af5bc85d LP |
226 | return nlmsgerr->error; |
227 | ||
228 | return response.header.nlmsg_seq; | |
229 | } | |
230 | ||
2c3ff76e | 231 | static int check_loopback(void) { |
e62d8c39 ZJS |
232 | int r; |
233 | int _cleanup_close_ fd; | |
2c3ff76e LP |
234 | union { |
235 | struct sockaddr sa; | |
236 | struct sockaddr_in in; | |
237 | } sa; | |
238 | ||
239 | /* If we failed to set up the loop back device, check whether | |
240 | * it might already be set up */ | |
241 | ||
242 | fd = socket(AF_INET, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0); | |
243 | if (fd < 0) | |
244 | return -errno; | |
245 | ||
246 | zero(sa); | |
247 | sa.in.sin_family = AF_INET; | |
248 | sa.in.sin_addr.s_addr = INADDR_LOOPBACK; | |
249 | ||
250 | if (bind(fd, &sa.sa, sizeof(sa.in)) >= 0) | |
251 | r = 1; | |
252 | else | |
253 | r = errno == EADDRNOTAVAIL ? 0 : -errno; | |
254 | ||
2c3ff76e LP |
255 | return r; |
256 | } | |
257 | ||
af5bc85d LP |
258 | int loopback_setup(void) { |
259 | int r, if_loopback; | |
260 | union { | |
261 | struct sockaddr sa; | |
262 | struct sockaddr_nl nl; | |
af5bc85d | 263 | } sa; |
5bfcc1c6 | 264 | unsigned requests = 0, i; |
e62d8c39 | 265 | int _cleanup_close_ fd = -1; |
2c3ff76e | 266 | bool eperm = false; |
af5bc85d LP |
267 | |
268 | errno = 0; | |
2c3ff76e LP |
269 | if_loopback = (int) if_nametoindex("lo"); |
270 | if (if_loopback <= 0) | |
af5bc85d LP |
271 | return errno ? -errno : -ENODEV; |
272 | ||
2c3ff76e LP |
273 | fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE); |
274 | if (fd < 0) | |
af5bc85d LP |
275 | return -errno; |
276 | ||
277 | zero(sa); | |
278 | sa.nl.nl_family = AF_NETLINK; | |
af5bc85d LP |
279 | if (bind(fd, &sa.sa, sizeof(sa)) < 0) { |
280 | r = -errno; | |
e62d8c39 | 281 | goto error; |
af5bc85d LP |
282 | } |
283 | ||
2c3ff76e LP |
284 | r = add_adresses(fd, if_loopback, &requests); |
285 | if (r < 0) | |
e62d8c39 | 286 | goto error; |
af5bc85d | 287 | |
2c3ff76e LP |
288 | r = start_interface(fd, if_loopback, &requests); |
289 | if (r < 0) | |
e62d8c39 | 290 | goto error; |
af5bc85d | 291 | |
5bfcc1c6 | 292 | for (i = 0; i < requests; i++) { |
2c3ff76e LP |
293 | r = read_response(fd, requests); |
294 | ||
295 | if (r == -EPERM) | |
296 | eperm = true; | |
297 | else if (r < 0) | |
e62d8c39 | 298 | goto error; |
5bfcc1c6 | 299 | } |
af5bc85d | 300 | |
2c3ff76e LP |
301 | if (eperm && check_loopback() < 0) { |
302 | r = -EPERM; | |
e62d8c39 | 303 | goto error; |
2c3ff76e LP |
304 | } |
305 | ||
e62d8c39 | 306 | return 0; |
af5bc85d | 307 | |
e62d8c39 ZJS |
308 | error: |
309 | log_warning("Failed to configure loopback device: %s", strerror(-r)); | |
af5bc85d LP |
310 | return r; |
311 | } |