1
2
3
4#include <stdlib.h>
5#include <memory.h>
6#include <unistd.h>
7#include <linux/bpf.h>
8#include <linux/rtnetlink.h>
9#include <sys/socket.h>
10#include <errno.h>
11#include <time.h>
12
13#include "bpf.h"
14#include "libbpf.h"
15#include "libbpf_internal.h"
16#include "nlattr.h"
17
18#ifndef SOL_NETLINK
19#define SOL_NETLINK 270
20#endif
21
22typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
23
24typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
25 void *cookie);
26
27struct xdp_id_md {
28 int ifindex;
29 __u32 flags;
30 struct xdp_link_info info;
31};
32
33static int libbpf_netlink_open(__u32 *nl_pid)
34{
35 struct sockaddr_nl sa;
36 socklen_t addrlen;
37 int one = 1, ret;
38 int sock;
39
40 memset(&sa, 0, sizeof(sa));
41 sa.nl_family = AF_NETLINK;
42
43 sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
44 if (sock < 0)
45 return -errno;
46
47 if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
48 &one, sizeof(one)) < 0) {
49 pr_warn("Netlink error reporting not supported\n");
50 }
51
52 if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
53 ret = -errno;
54 goto cleanup;
55 }
56
57 addrlen = sizeof(sa);
58 if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
59 ret = -errno;
60 goto cleanup;
61 }
62
63 if (addrlen != sizeof(sa)) {
64 ret = -LIBBPF_ERRNO__INTERNAL;
65 goto cleanup;
66 }
67
68 *nl_pid = sa.nl_pid;
69 return sock;
70
71cleanup:
72 close(sock);
73 return ret;
74}
75
76static int bpf_netlink_recv(int sock, __u32 nl_pid, int seq,
77 __dump_nlmsg_t _fn, libbpf_dump_nlmsg_t fn,
78 void *cookie)
79{
80 bool multipart = true;
81 struct nlmsgerr *err;
82 struct nlmsghdr *nh;
83 char buf[4096];
84 int len, ret;
85
86 while (multipart) {
87 multipart = false;
88 len = recv(sock, buf, sizeof(buf), 0);
89 if (len < 0) {
90 ret = -errno;
91 goto done;
92 }
93
94 if (len == 0)
95 break;
96
97 for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
98 nh = NLMSG_NEXT(nh, len)) {
99 if (nh->nlmsg_pid != nl_pid) {
100 ret = -LIBBPF_ERRNO__WRNGPID;
101 goto done;
102 }
103 if (nh->nlmsg_seq != seq) {
104 ret = -LIBBPF_ERRNO__INVSEQ;
105 goto done;
106 }
107 if (nh->nlmsg_flags & NLM_F_MULTI)
108 multipart = true;
109 switch (nh->nlmsg_type) {
110 case NLMSG_ERROR:
111 err = (struct nlmsgerr *)NLMSG_DATA(nh);
112 if (!err->error)
113 continue;
114 ret = err->error;
115 libbpf_nla_dump_errormsg(nh);
116 goto done;
117 case NLMSG_DONE:
118 return 0;
119 default:
120 break;
121 }
122 if (_fn) {
123 ret = _fn(nh, fn, cookie);
124 if (ret)
125 return ret;
126 }
127 }
128 }
129 ret = 0;
130done:
131 return ret;
132}
133
134static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,
135 __u32 flags)
136{
137 int sock, seq = 0, ret;
138 struct nlattr *nla, *nla_xdp;
139 struct {
140 struct nlmsghdr nh;
141 struct ifinfomsg ifinfo;
142 char attrbuf[64];
143 } req;
144 __u32 nl_pid = 0;
145
146 sock = libbpf_netlink_open(&nl_pid);
147 if (sock < 0)
148 return sock;
149
150 memset(&req, 0, sizeof(req));
151 req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
152 req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
153 req.nh.nlmsg_type = RTM_SETLINK;
154 req.nh.nlmsg_pid = 0;
155 req.nh.nlmsg_seq = ++seq;
156 req.ifinfo.ifi_family = AF_UNSPEC;
157 req.ifinfo.ifi_index = ifindex;
158
159
160 nla = (struct nlattr *)(((char *)&req)
161 + NLMSG_ALIGN(req.nh.nlmsg_len));
162 nla->nla_type = NLA_F_NESTED | IFLA_XDP;
163 nla->nla_len = NLA_HDRLEN;
164
165
166 nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
167 nla_xdp->nla_type = IFLA_XDP_FD;
168 nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
169 memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));
170 nla->nla_len += nla_xdp->nla_len;
171
172
173 if (flags) {
174 nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
175 nla_xdp->nla_type = IFLA_XDP_FLAGS;
176 nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags);
177 memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags));
178 nla->nla_len += nla_xdp->nla_len;
179 }
180
181 if (flags & XDP_FLAGS_REPLACE) {
182 nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
183 nla_xdp->nla_type = IFLA_XDP_EXPECTED_FD;
184 nla_xdp->nla_len = NLA_HDRLEN + sizeof(old_fd);
185 memcpy((char *)nla_xdp + NLA_HDRLEN, &old_fd, sizeof(old_fd));
186 nla->nla_len += nla_xdp->nla_len;
187 }
188
189 req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
190
191 if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
192 ret = -errno;
193 goto cleanup;
194 }
195 ret = bpf_netlink_recv(sock, nl_pid, seq, NULL, NULL, NULL);
196
197cleanup:
198 close(sock);
199 return ret;
200}
201
202int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,
203 const struct bpf_xdp_set_link_opts *opts)
204{
205 int old_fd = -1;
206
207 if (!OPTS_VALID(opts, bpf_xdp_set_link_opts))
208 return -EINVAL;
209
210 if (OPTS_HAS(opts, old_fd)) {
211 old_fd = OPTS_GET(opts, old_fd, -1);
212 flags |= XDP_FLAGS_REPLACE;
213 }
214
215 return __bpf_set_link_xdp_fd_replace(ifindex, fd,
216 old_fd,
217 flags);
218}
219
220int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
221{
222 return __bpf_set_link_xdp_fd_replace(ifindex, fd, 0, flags);
223}
224
225static int __dump_link_nlmsg(struct nlmsghdr *nlh,
226 libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
227{
228 struct nlattr *tb[IFLA_MAX + 1], *attr;
229 struct ifinfomsg *ifi = NLMSG_DATA(nlh);
230 int len;
231
232 len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
233 attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
234 if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
235 return -LIBBPF_ERRNO__NLPARSE;
236
237 return dump_link_nlmsg(cookie, ifi, tb);
238}
239
240static int get_xdp_info(void *cookie, void *msg, struct nlattr **tb)
241{
242 struct nlattr *xdp_tb[IFLA_XDP_MAX + 1];
243 struct xdp_id_md *xdp_id = cookie;
244 struct ifinfomsg *ifinfo = msg;
245 int ret;
246
247 if (xdp_id->ifindex && xdp_id->ifindex != ifinfo->ifi_index)
248 return 0;
249
250 if (!tb[IFLA_XDP])
251 return 0;
252
253 ret = libbpf_nla_parse_nested(xdp_tb, IFLA_XDP_MAX, tb[IFLA_XDP], NULL);
254 if (ret)
255 return ret;
256
257 if (!xdp_tb[IFLA_XDP_ATTACHED])
258 return 0;
259
260 xdp_id->info.attach_mode = libbpf_nla_getattr_u8(
261 xdp_tb[IFLA_XDP_ATTACHED]);
262
263 if (xdp_id->info.attach_mode == XDP_ATTACHED_NONE)
264 return 0;
265
266 if (xdp_tb[IFLA_XDP_PROG_ID])
267 xdp_id->info.prog_id = libbpf_nla_getattr_u32(
268 xdp_tb[IFLA_XDP_PROG_ID]);
269
270 if (xdp_tb[IFLA_XDP_SKB_PROG_ID])
271 xdp_id->info.skb_prog_id = libbpf_nla_getattr_u32(
272 xdp_tb[IFLA_XDP_SKB_PROG_ID]);
273
274 if (xdp_tb[IFLA_XDP_DRV_PROG_ID])
275 xdp_id->info.drv_prog_id = libbpf_nla_getattr_u32(
276 xdp_tb[IFLA_XDP_DRV_PROG_ID]);
277
278 if (xdp_tb[IFLA_XDP_HW_PROG_ID])
279 xdp_id->info.hw_prog_id = libbpf_nla_getattr_u32(
280 xdp_tb[IFLA_XDP_HW_PROG_ID]);
281
282 return 0;
283}
284
285static int libbpf_nl_get_link(int sock, unsigned int nl_pid,
286 libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie);
287
288int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
289 size_t info_size, __u32 flags)
290{
291 struct xdp_id_md xdp_id = {};
292 int sock, ret;
293 __u32 nl_pid = 0;
294 __u32 mask;
295
296 if (flags & ~XDP_FLAGS_MASK || !info_size)
297 return -EINVAL;
298
299
300 flags &= (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE);
301 mask = flags - 1;
302 if (flags && flags & mask)
303 return -EINVAL;
304
305 sock = libbpf_netlink_open(&nl_pid);
306 if (sock < 0)
307 return sock;
308
309 xdp_id.ifindex = ifindex;
310 xdp_id.flags = flags;
311
312 ret = libbpf_nl_get_link(sock, nl_pid, get_xdp_info, &xdp_id);
313 if (!ret) {
314 size_t sz = min(info_size, sizeof(xdp_id.info));
315
316 memcpy(info, &xdp_id.info, sz);
317 memset((void *) info + sz, 0, info_size - sz);
318 }
319
320 close(sock);
321 return ret;
322}
323
324static __u32 get_xdp_id(struct xdp_link_info *info, __u32 flags)
325{
326 flags &= XDP_FLAGS_MODES;
327
328 if (info->attach_mode != XDP_ATTACHED_MULTI && !flags)
329 return info->prog_id;
330 if (flags & XDP_FLAGS_DRV_MODE)
331 return info->drv_prog_id;
332 if (flags & XDP_FLAGS_HW_MODE)
333 return info->hw_prog_id;
334 if (flags & XDP_FLAGS_SKB_MODE)
335 return info->skb_prog_id;
336
337 return 0;
338}
339
340int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
341{
342 struct xdp_link_info info;
343 int ret;
344
345 ret = bpf_get_link_xdp_info(ifindex, &info, sizeof(info), flags);
346 if (!ret)
347 *prog_id = get_xdp_id(&info, flags);
348
349 return ret;
350}
351
352int libbpf_nl_get_link(int sock, unsigned int nl_pid,
353 libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
354{
355 struct {
356 struct nlmsghdr nlh;
357 struct ifinfomsg ifm;
358 } req = {
359 .nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
360 .nlh.nlmsg_type = RTM_GETLINK,
361 .nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
362 .ifm.ifi_family = AF_PACKET,
363 };
364 int seq = time(NULL);
365
366 req.nlh.nlmsg_seq = seq;
367 if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
368 return -errno;
369
370 return bpf_netlink_recv(sock, nl_pid, seq, __dump_link_nlmsg,
371 dump_link_nlmsg, cookie);
372}
373
