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borkmannKernel Patches Daemon
borkmann
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Kernel Patches Daemon
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selftests/bpf: Add netlink helper library
Add a basic netlink helper library for the BPF selftests. This has been taken and cut down/cleaned up from iproute2. More can be added at some later point in time when needed, but for now this covers basics such as device creation which we need for BPF selftests / BPF CI. Signed-off-by: Daniel Borkmann <[email protected]>
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3 files changed

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‎tools/testing/selftests/bpf/Makefile

Lines changed: 14 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -579,11 +579,20 @@ endef
579579
# Define test_progs test runner.
580580
TRUNNER_TESTS_DIR := prog_tests
581581
TRUNNER_BPF_PROGS_DIR := progs
582-
TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \
583-
network_helpers.c testing_helpers.c \
584-
btf_helpers.c flow_dissector_load.h \
585-
cap_helpers.c test_loader.c xsk.c disasm.c \
586-
json_writer.c unpriv_helpers.c \
582+
TRUNNER_EXTRA_SOURCES := test_progs.c \
583+
cgroup_helpers.c \
584+
trace_helpers.c \
585+
network_helpers.c \
586+
testing_helpers.c \
587+
btf_helpers.c \
588+
cap_helpers.c \
589+
unpriv_helpers.c \
590+
netlink_helpers.c \
591+
test_loader.c \
592+
xsk.c \
593+
disasm.c \
594+
json_writer.c \
595+
flow_dissector_load.h \
587596
ip_check_defrag_frags.h
588597
TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \
589598
$(OUTPUT)/liburandom_read.so \

‎tools/testing/selftests/bpf/netlink_helpers.c

Lines changed: 358 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,358 @@
1+
// SPDX-License-Identifier: GPL-2.0-or-later
2+
/* Taken & modified from iproute2's libnetlink.c
3+
* Authors: Alexey Kuznetsov, <[email protected]>
4+
*/
5+
#include <stdio.h>
6+
#include <stdlib.h>
7+
#include <unistd.h>
8+
#include <errno.h>
9+
#include <time.h>
10+
#include <sys/socket.h>
11+
12+
#include "netlink_helpers.h"
13+
14+
static int rcvbuf = 1024 * 1024;
15+
16+
void rtnl_close(struct rtnl_handle *rth)
17+
{
18+
if (rth->fd >= 0) {
19+
close(rth->fd);
20+
rth->fd = -1;
21+
}
22+
}
23+
24+
int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
25+
int protocol)
26+
{
27+
socklen_t addr_len;
28+
int sndbuf = 32768;
29+
int one = 1;
30+
31+
memset(rth, 0, sizeof(*rth));
32+
rth->proto = protocol;
33+
rth->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, protocol);
34+
if (rth->fd < 0) {
35+
perror("Cannot open netlink socket");
36+
return -1;
37+
}
38+
if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF,
39+
&sndbuf, sizeof(sndbuf)) < 0) {
40+
perror("SO_SNDBUF");
41+
goto err;
42+
}
43+
if (setsockopt(rth->fd, SOL_SOCKET, SO_RCVBUF,
44+
&rcvbuf, sizeof(rcvbuf)) < 0) {
45+
perror("SO_RCVBUF");
46+
goto err;
47+
}
48+
49+
/* Older kernels may no support extended ACK reporting */
50+
setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,
51+
&one, sizeof(one));
52+
53+
memset(&rth->local, 0, sizeof(rth->local));
54+
rth->local.nl_family = AF_NETLINK;
55+
rth->local.nl_groups = subscriptions;
56+
57+
if (bind(rth->fd, (struct sockaddr *)&rth->local,
58+
sizeof(rth->local)) < 0) {
59+
perror("Cannot bind netlink socket");
60+
goto err;
61+
}
62+
addr_len = sizeof(rth->local);
63+
if (getsockname(rth->fd, (struct sockaddr *)&rth->local,
64+
&addr_len) < 0) {
65+
perror("Cannot getsockname");
66+
goto err;
67+
}
68+
if (addr_len != sizeof(rth->local)) {
69+
fprintf(stderr, "Wrong address length %d\n", addr_len);
70+
goto err;
71+
}
72+
if (rth->local.nl_family != AF_NETLINK) {
73+
fprintf(stderr, "Wrong address family %d\n",
74+
rth->local.nl_family);
75+
goto err;
76+
}
77+
rth->seq = time(NULL);
78+
return 0;
79+
err:
80+
rtnl_close(rth);
81+
return -1;
82+
}
83+
84+
int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
85+
{
86+
return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
87+
}
88+
89+
static int __rtnl_recvmsg(int fd, struct msghdr *msg, int flags)
90+
{
91+
int len;
92+
93+
do {
94+
len = recvmsg(fd, msg, flags);
95+
} while (len < 0 && (errno == EINTR || errno == EAGAIN));
96+
if (len < 0) {
97+
fprintf(stderr, "netlink receive error %s (%d)\n",
98+
strerror(errno), errno);
99+
return -errno;
100+
}
101+
if (len == 0) {
102+
fprintf(stderr, "EOF on netlink\n");
103+
return -ENODATA;
104+
}
105+
return len;
106+
}
107+
108+
static int rtnl_recvmsg(int fd, struct msghdr *msg, char **answer)
109+
{
110+
struct iovec *iov = msg->msg_iov;
111+
char *buf;
112+
int len;
113+
114+
iov->iov_base = NULL;
115+
iov->iov_len = 0;
116+
117+
len = __rtnl_recvmsg(fd, msg, MSG_PEEK | MSG_TRUNC);
118+
if (len < 0)
119+
return len;
120+
if (len < 32768)
121+
len = 32768;
122+
buf = malloc(len);
123+
if (!buf) {
124+
fprintf(stderr, "malloc error: not enough buffer\n");
125+
return -ENOMEM;
126+
}
127+
iov->iov_base = buf;
128+
iov->iov_len = len;
129+
len = __rtnl_recvmsg(fd, msg, 0);
130+
if (len < 0) {
131+
free(buf);
132+
return len;
133+
}
134+
if (answer)
135+
*answer = buf;
136+
else
137+
free(buf);
138+
return len;
139+
}
140+
141+
static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,
142+
nl_ext_ack_fn_t errfn)
143+
{
144+
fprintf(stderr, "RTNETLINK answers: %s\n",
145+
strerror(-err->error));
146+
}
147+
148+
static int __rtnl_talk_iov(struct rtnl_handle *rtnl, struct iovec *iov,
149+
size_t iovlen, struct nlmsghdr **answer,
150+
bool show_rtnl_err, nl_ext_ack_fn_t errfn)
151+
{
152+
struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
153+
struct iovec riov;
154+
struct msghdr msg = {
155+
.msg_name = &nladdr,
156+
.msg_namelen = sizeof(nladdr),
157+
.msg_iov = iov,
158+
.msg_iovlen = iovlen,
159+
};
160+
unsigned int seq = 0;
161+
struct nlmsghdr *h;
162+
int i, status;
163+
char *buf;
164+
165+
for (i = 0; i < iovlen; i++) {
166+
h = iov[i].iov_base;
167+
h->nlmsg_seq = seq = ++rtnl->seq;
168+
if (answer == NULL)
169+
h->nlmsg_flags |= NLM_F_ACK;
170+
}
171+
status = sendmsg(rtnl->fd, &msg, 0);
172+
if (status < 0) {
173+
perror("Cannot talk to rtnetlink");
174+
return -1;
175+
}
176+
/* change msg to use the response iov */
177+
msg.msg_iov = &riov;
178+
msg.msg_iovlen = 1;
179+
i = 0;
180+
while (1) {
181+
next:
182+
status = rtnl_recvmsg(rtnl->fd, &msg, &buf);
183+
++i;
184+
if (status < 0)
185+
return status;
186+
if (msg.msg_namelen != sizeof(nladdr)) {
187+
fprintf(stderr,
188+
"Sender address length == %d!\n",
189+
msg.msg_namelen);
190+
exit(1);
191+
}
192+
for (h = (struct nlmsghdr *)buf; status >= sizeof(*h); ) {
193+
int len = h->nlmsg_len;
194+
int l = len - sizeof(*h);
195+
196+
if (l < 0 || len > status) {
197+
if (msg.msg_flags & MSG_TRUNC) {
198+
fprintf(stderr, "Truncated message!\n");
199+
free(buf);
200+
return -1;
201+
}
202+
fprintf(stderr,
203+
"Malformed message: len=%d!\n",
204+
len);
205+
exit(1);
206+
}
207+
if (nladdr.nl_pid != 0 ||
208+
h->nlmsg_pid != rtnl->local.nl_pid ||
209+
h->nlmsg_seq > seq || h->nlmsg_seq < seq - iovlen) {
210+
/* Don't forget to skip that message. */
211+
status -= NLMSG_ALIGN(len);
212+
h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
213+
continue;
214+
}
215+
if (h->nlmsg_type == NLMSG_ERROR) {
216+
struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
217+
int error = err->error;
218+
219+
if (l < sizeof(struct nlmsgerr)) {
220+
fprintf(stderr, "ERROR truncated\n");
221+
free(buf);
222+
return -1;
223+
}
224+
if (error) {
225+
errno = -error;
226+
if (rtnl->proto != NETLINK_SOCK_DIAG &&
227+
show_rtnl_err)
228+
rtnl_talk_error(h, err, errfn);
229+
}
230+
if (i < iovlen) {
231+
free(buf);
232+
goto next;
233+
}
234+
if (error) {
235+
free(buf);
236+
return -i;
237+
}
238+
if (answer)
239+
*answer = (struct nlmsghdr *)buf;
240+
else
241+
free(buf);
242+
return 0;
243+
}
244+
if (answer) {
245+
*answer = (struct nlmsghdr *)buf;
246+
return 0;
247+
}
248+
fprintf(stderr, "Unexpected reply!\n");
249+
status -= NLMSG_ALIGN(len);
250+
h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
251+
}
252+
free(buf);
253+
if (msg.msg_flags & MSG_TRUNC) {
254+
fprintf(stderr, "Message truncated!\n");
255+
continue;
256+
}
257+
if (status) {
258+
fprintf(stderr, "Remnant of size %d!\n", status);
259+
exit(1);
260+
}
261+
}
262+
}
263+
264+
static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
265+
struct nlmsghdr **answer, bool show_rtnl_err,
266+
nl_ext_ack_fn_t errfn)
267+
{
268+
struct iovec iov = {
269+
.iov_base = n,
270+
.iov_len = n->nlmsg_len,
271+
};
272+
273+
return __rtnl_talk_iov(rtnl, &iov, 1, answer, show_rtnl_err, errfn);
274+
}
275+
276+
int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
277+
struct nlmsghdr **answer)
278+
{
279+
return __rtnl_talk(rtnl, n, answer, true, NULL);
280+
}
281+
282+
int addattr(struct nlmsghdr *n, int maxlen, int type)
283+
{
284+
return addattr_l(n, maxlen, type, NULL, 0);
285+
}
286+
287+
int addattr8(struct nlmsghdr *n, int maxlen, int type, __u8 data)
288+
{
289+
return addattr_l(n, maxlen, type, &data, sizeof(__u8));
290+
}
291+
292+
int addattr16(struct nlmsghdr *n, int maxlen, int type, __u16 data)
293+
{
294+
return addattr_l(n, maxlen, type, &data, sizeof(__u16));
295+
}
296+
297+
int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
298+
{
299+
return addattr_l(n, maxlen, type, &data, sizeof(__u32));
300+
}
301+
302+
int addattr64(struct nlmsghdr *n, int maxlen, int type, __u64 data)
303+
{
304+
return addattr_l(n, maxlen, type, &data, sizeof(__u64));
305+
}
306+
307+
int addattrstrz(struct nlmsghdr *n, int maxlen, int type, const char *str)
308+
{
309+
return addattr_l(n, maxlen, type, str, strlen(str)+1);
310+
}
311+
312+
int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
313+
int alen)
314+
{
315+
int len = RTA_LENGTH(alen);
316+
struct rtattr *rta;
317+
318+
if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
319+
fprintf(stderr, "%s: Message exceeded bound of %d\n",
320+
__func__, maxlen);
321+
return -1;
322+
}
323+
rta = NLMSG_TAIL(n);
324+
rta->rta_type = type;
325+
rta->rta_len = len;
326+
if (alen)
327+
memcpy(RTA_DATA(rta), data, alen);
328+
n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
329+
return 0;
330+
}
331+
332+
int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
333+
{
334+
if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
335+
fprintf(stderr, "%s: Message exceeded bound of %d\n",
336+
__func__, maxlen);
337+
return -1;
338+
}
339+
340+
memcpy(NLMSG_TAIL(n), data, len);
341+
memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
342+
n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
343+
return 0;
344+
}
345+
346+
struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
347+
{
348+
struct rtattr *nest = NLMSG_TAIL(n);
349+
350+
addattr_l(n, maxlen, type, NULL, 0);
351+
return nest;
352+
}
353+
354+
int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
355+
{
356+
nest->rta_len = (void *)NLMSG_TAIL(n) - (void *)nest;
357+
return n->nlmsg_len;
358+
}

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