diff mbox series

[bpf-next,7/8] selftests/bpf: Add netlink helper library

Message ID 20230926055913.9859-8-daniel@iogearbox.net (mailing list archive)
State Changes Requested
Delegated to: BPF
Headers show
Series Add bpf programmable device | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers warning 10 maintainers not CCed: linux-kselftest@vger.kernel.org shuah@kernel.org mykolal@fb.com martin.lau@linux.dev jolsa@kernel.org haoluo@google.com sdf@google.com yonghong.song@linux.dev kpsingh@kernel.org song@kernel.org
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 9 this patch: 9
netdev/checkpatch warning CHECK: Comparison to NULL could be written "!answer" CHECK: No space is necessary after a cast CHECK: multiple assignments should be avoided CHECK: spaces preferred around that '+' (ctx:VxV) WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? WARNING: line length of 84 exceeds 80 columns WARNING: line length of 86 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-0 success Logs for ${{ matrix.test }} on ${{ matrix.arch }} with ${{ matrix.toolchain_full }}
bpf/vmtest-bpf-next-VM_Test-1 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-2 success Logs for build for aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-3 success Logs for build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-4 success Logs for build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-5 fail Logs for build for x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-6 success Logs for set-matrix
bpf/vmtest-bpf-next-VM_Test-7 success Logs for veristat

Commit Message

Daniel Borkmann Sept. 26, 2023, 5:59 a.m. UTC 
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 <daniel@iogearbox.net>
---
 tools/testing/selftests/bpf/Makefile          |  19 +-
 tools/testing/selftests/bpf/netlink_helpers.c | 358 ++++++++++++++++++
 tools/testing/selftests/bpf/netlink_helpers.h |  46 +++
 3 files changed, 418 insertions(+), 5 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/netlink_helpers.c
 create mode 100644 tools/testing/selftests/bpf/netlink_helpers.h

Comments

Stanislav Fomichev Sept. 26, 2023, 9:35 p.m. UTC | #1 
On 09/26, Daniel Borkmann wrote:
> 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.

Should the netlink code be based on ynl
(https://lore.kernel.org/all/20230825122756.7603-1-donald.hunter@gmail.com/)?
Or it doesn't have full rtnl support yet?

> 
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> ---
>  tools/testing/selftests/bpf/Makefile          |  19 +-
>  tools/testing/selftests/bpf/netlink_helpers.c | 358 ++++++++++++++++++
>  tools/testing/selftests/bpf/netlink_helpers.h |  46 +++
>  3 files changed, 418 insertions(+), 5 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/netlink_helpers.c
>  create mode 100644 tools/testing/selftests/bpf/netlink_helpers.h
> 
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 47365161b6fc..b8186ceb31dc 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -579,11 +579,20 @@ endef
>  # Define test_progs test runner.
>  TRUNNER_TESTS_DIR := prog_tests
>  TRUNNER_BPF_PROGS_DIR := progs
> -TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c	\
> -			 network_helpers.c testing_helpers.c		\
> -			 btf_helpers.c flow_dissector_load.h		\
> -			 cap_helpers.c test_loader.c xsk.c disasm.c	\
> -			 json_writer.c unpriv_helpers.c 		\
> +TRUNNER_EXTRA_SOURCES := test_progs.c		\
> +			 cgroup_helpers.c	\
> +			 trace_helpers.c	\
> +			 network_helpers.c	\
> +			 testing_helpers.c	\
> +			 btf_helpers.c		\
> +			 cap_helpers.c		\
> +			 unpriv_helpers.c 	\
> +			 netlink_helpers.c	\
> +			 test_loader.c		\
> +			 xsk.c			\
> +			 disasm.c		\
> +			 json_writer.c 		\
> +			 flow_dissector_load.h	\
>  			 ip_check_defrag_frags.h
>  TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko	\
>  		       $(OUTPUT)/liburandom_read.so			\
> diff --git a/tools/testing/selftests/bpf/netlink_helpers.c b/tools/testing/selftests/bpf/netlink_helpers.c
> new file mode 100644
> index 000000000000..caf36eb1d032
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/netlink_helpers.c
> @@ -0,0 +1,358 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/* Taken & modified from iproute2's libnetlink.c
> + * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
> + */
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <errno.h>
> +#include <time.h>
> +#include <sys/socket.h>
> +
> +#include "netlink_helpers.h"
> +
> +static int rcvbuf = 1024 * 1024;
> +
> +void rtnl_close(struct rtnl_handle *rth)
> +{
> +	if (rth->fd >= 0) {
> +		close(rth->fd);
> +		rth->fd = -1;
> +	}
> +}
> +
> +int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
> +		      int protocol)
> +{
> +	socklen_t addr_len;
> +	int sndbuf = 32768;
> +	int one = 1;
> +
> +	memset(rth, 0, sizeof(*rth));
> +	rth->proto = protocol;
> +	rth->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, protocol);
> +	if (rth->fd < 0) {
> +		perror("Cannot open netlink socket");
> +		return -1;
> +	}
> +	if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF,
> +		       &sndbuf, sizeof(sndbuf)) < 0) {
> +		perror("SO_SNDBUF");
> +		goto err;
> +	}
> +	if (setsockopt(rth->fd, SOL_SOCKET, SO_RCVBUF,
> +		       &rcvbuf, sizeof(rcvbuf)) < 0) {
> +		perror("SO_RCVBUF");
> +		goto err;
> +	}
> +
> +	/* Older kernels may no support extended ACK reporting */
> +	setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,
> +		   &one, sizeof(one));
> +
> +	memset(&rth->local, 0, sizeof(rth->local));
> +	rth->local.nl_family = AF_NETLINK;
> +	rth->local.nl_groups = subscriptions;
> +
> +	if (bind(rth->fd, (struct sockaddr *)&rth->local,
> +		 sizeof(rth->local)) < 0) {
> +		perror("Cannot bind netlink socket");
> +		goto err;
> +	}
> +	addr_len = sizeof(rth->local);
> +	if (getsockname(rth->fd, (struct sockaddr *)&rth->local,
> +			&addr_len) < 0) {
> +		perror("Cannot getsockname");
> +		goto err;
> +	}
> +	if (addr_len != sizeof(rth->local)) {
> +		fprintf(stderr, "Wrong address length %d\n", addr_len);
> +		goto err;
> +	}
> +	if (rth->local.nl_family != AF_NETLINK) {
> +		fprintf(stderr, "Wrong address family %d\n",
> +			rth->local.nl_family);
> +		goto err;
> +	}
> +	rth->seq = time(NULL);
> +	return 0;
> +err:
> +	rtnl_close(rth);
> +	return -1;
> +}
> +
> +int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
> +{
> +	return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
> +}
> +
> +static int __rtnl_recvmsg(int fd, struct msghdr *msg, int flags)
> +{
> +	int len;
> +
> +	do {
> +		len = recvmsg(fd, msg, flags);
> +	} while (len < 0 && (errno == EINTR || errno == EAGAIN));
> +	if (len < 0) {
> +		fprintf(stderr, "netlink receive error %s (%d)\n",
> +			strerror(errno), errno);
> +		return -errno;
> +	}
> +	if (len == 0) {
> +		fprintf(stderr, "EOF on netlink\n");
> +		return -ENODATA;
> +	}
> +	return len;
> +}
> +
> +static int rtnl_recvmsg(int fd, struct msghdr *msg, char **answer)
> +{
> +	struct iovec *iov = msg->msg_iov;
> +	char *buf;
> +	int len;
> +
> +	iov->iov_base = NULL;
> +	iov->iov_len = 0;
> +
> +	len = __rtnl_recvmsg(fd, msg, MSG_PEEK | MSG_TRUNC);
> +	if (len < 0)
> +		return len;
> +	if (len < 32768)
> +		len = 32768;
> +	buf = malloc(len);
> +	if (!buf) {
> +		fprintf(stderr, "malloc error: not enough buffer\n");
> +		return -ENOMEM;
> +	}
> +	iov->iov_base = buf;
> +	iov->iov_len = len;
> +	len = __rtnl_recvmsg(fd, msg, 0);
> +	if (len < 0) {
> +		free(buf);
> +		return len;
> +	}
> +	if (answer)
> +		*answer = buf;
> +	else
> +		free(buf);
> +	return len;
> +}
> +
> +static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,
> +			    nl_ext_ack_fn_t errfn)
> +{
> +	fprintf(stderr, "RTNETLINK answers: %s\n",
> +		strerror(-err->error));
> +}
> +
> +static int __rtnl_talk_iov(struct rtnl_handle *rtnl, struct iovec *iov,
> +			   size_t iovlen, struct nlmsghdr **answer,
> +			   bool show_rtnl_err, nl_ext_ack_fn_t errfn)
> +{
> +	struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
> +	struct iovec riov;
> +	struct msghdr msg = {
> +		.msg_name	= &nladdr,
> +		.msg_namelen	= sizeof(nladdr),
> +		.msg_iov	= iov,
> +		.msg_iovlen	= iovlen,
> +	};
> +	unsigned int seq = 0;
> +	struct nlmsghdr *h;
> +	int i, status;
> +	char *buf;
> +
> +	for (i = 0; i < iovlen; i++) {
> +		h = iov[i].iov_base;
> +		h->nlmsg_seq = seq = ++rtnl->seq;
> +		if (answer == NULL)
> +			h->nlmsg_flags |= NLM_F_ACK;
> +	}
> +	status = sendmsg(rtnl->fd, &msg, 0);
> +	if (status < 0) {
> +		perror("Cannot talk to rtnetlink");
> +		return -1;
> +	}
> +	/* change msg to use the response iov */
> +	msg.msg_iov = &riov;
> +	msg.msg_iovlen = 1;
> +	i = 0;
> +	while (1) {
> +next:
> +		status = rtnl_recvmsg(rtnl->fd, &msg, &buf);
> +		++i;
> +		if (status < 0)
> +			return status;
> +		if (msg.msg_namelen != sizeof(nladdr)) {
> +			fprintf(stderr,
> +				"Sender address length == %d!\n",
> +				msg.msg_namelen);
> +			exit(1);
> +		}
> +		for (h = (struct nlmsghdr *)buf; status >= sizeof(*h); ) {
> +			int len = h->nlmsg_len;
> +			int l = len - sizeof(*h);
> +
> +			if (l < 0 || len > status) {
> +				if (msg.msg_flags & MSG_TRUNC) {
> +					fprintf(stderr, "Truncated message!\n");
> +					free(buf);
> +					return -1;
> +				}
> +				fprintf(stderr,
> +					"Malformed message: len=%d!\n",
> +					len);
> +				exit(1);
> +			}
> +			if (nladdr.nl_pid != 0 ||
> +			    h->nlmsg_pid != rtnl->local.nl_pid ||
> +			    h->nlmsg_seq > seq || h->nlmsg_seq < seq - iovlen) {
> +				/* Don't forget to skip that message. */
> +				status -= NLMSG_ALIGN(len);
> +				h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
> +				continue;
> +			}
> +			if (h->nlmsg_type == NLMSG_ERROR) {
> +				struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
> +				int error = err->error;
> +
> +				if (l < sizeof(struct nlmsgerr)) {
> +					fprintf(stderr, "ERROR truncated\n");
> +					free(buf);
> +					return -1;
> +				}
> +				if (error) {
> +					errno = -error;
> +					if (rtnl->proto != NETLINK_SOCK_DIAG &&
> +					    show_rtnl_err)
> +						rtnl_talk_error(h, err, errfn);
> +				}
> +				if (i < iovlen) {
> +					free(buf);
> +					goto next;
> +				}
> +				if (error) {
> +					free(buf);
> +					return -i;
> +				}
> +				if (answer)
> +					*answer = (struct nlmsghdr *)buf;
> +				else
> +					free(buf);
> +				return 0;
> +			}
> +			if (answer) {
> +				*answer = (struct nlmsghdr *)buf;
> +				return 0;
> +			}
> +			fprintf(stderr, "Unexpected reply!\n");
> +			status -= NLMSG_ALIGN(len);
> +			h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
> +		}
> +		free(buf);
> +		if (msg.msg_flags & MSG_TRUNC) {
> +			fprintf(stderr, "Message truncated!\n");
> +			continue;
> +		}
> +		if (status) {
> +			fprintf(stderr, "Remnant of size %d!\n", status);
> +			exit(1);
> +		}
> +	}
> +}
> +
> +static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
> +		       struct nlmsghdr **answer, bool show_rtnl_err,
> +		       nl_ext_ack_fn_t errfn)
> +{
> +	struct iovec iov = {
> +		.iov_base	= n,
> +		.iov_len	= n->nlmsg_len,
> +	};
> +
> +	return __rtnl_talk_iov(rtnl, &iov, 1, answer, show_rtnl_err, errfn);
> +}
> +
> +int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
> +	      struct nlmsghdr **answer)
> +{
> +	return __rtnl_talk(rtnl, n, answer, true, NULL);
> +}
> +
> +int addattr(struct nlmsghdr *n, int maxlen, int type)
> +{
> +	return addattr_l(n, maxlen, type, NULL, 0);
> +}
> +
> +int addattr8(struct nlmsghdr *n, int maxlen, int type, __u8 data)
> +{
> +	return addattr_l(n, maxlen, type, &data, sizeof(__u8));
> +}
> +
> +int addattr16(struct nlmsghdr *n, int maxlen, int type, __u16 data)
> +{
> +	return addattr_l(n, maxlen, type, &data, sizeof(__u16));
> +}
> +
> +int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
> +{
> +	return addattr_l(n, maxlen, type, &data, sizeof(__u32));
> +}
> +
> +int addattr64(struct nlmsghdr *n, int maxlen, int type, __u64 data)
> +{
> +	return addattr_l(n, maxlen, type, &data, sizeof(__u64));
> +}
> +
> +int addattrstrz(struct nlmsghdr *n, int maxlen, int type, const char *str)
> +{
> +	return addattr_l(n, maxlen, type, str, strlen(str)+1);
> +}
> +
> +int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
> +	      int alen)
> +{
> +	int len = RTA_LENGTH(alen);
> +	struct rtattr *rta;
> +
> +	if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
> +		fprintf(stderr, "%s: Message exceeded bound of %d\n",
> +			__func__, maxlen);
> +		return -1;
> +	}
> +	rta = NLMSG_TAIL(n);
> +	rta->rta_type = type;
> +	rta->rta_len = len;
> +	if (alen)
> +		memcpy(RTA_DATA(rta), data, alen);
> +	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
> +	return 0;
> +}
> +
> +int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
> +{
> +	if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
> +		fprintf(stderr, "%s: Message exceeded bound of %d\n",
> +			__func__, maxlen);
> +		return -1;
> +	}
> +
> +	memcpy(NLMSG_TAIL(n), data, len);
> +	memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
> +	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
> +	return 0;
> +}
> +
> +struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
> +{
> +	struct rtattr *nest = NLMSG_TAIL(n);
> +
> +	addattr_l(n, maxlen, type, NULL, 0);
> +	return nest;
> +}
> +
> +int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
> +{
> +	nest->rta_len = (void *)NLMSG_TAIL(n) - (void *)nest;
> +	return n->nlmsg_len;
> +}
> diff --git a/tools/testing/selftests/bpf/netlink_helpers.h b/tools/testing/selftests/bpf/netlink_helpers.h
> new file mode 100644
> index 000000000000..68116818a47e
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/netlink_helpers.h
> @@ -0,0 +1,46 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef NETLINK_HELPERS_H
> +#define NETLINK_HELPERS_H
> +
> +#include <string.h>
> +#include <linux/netlink.h>
> +#include <linux/rtnetlink.h>
> +
> +struct rtnl_handle {
> +	int			fd;
> +	struct sockaddr_nl	local;
> +	struct sockaddr_nl	peer;
> +	__u32			seq;
> +	__u32			dump;
> +	int			proto;
> +	FILE			*dump_fp;
> +#define RTNL_HANDLE_F_LISTEN_ALL_NSID		0x01
> +#define RTNL_HANDLE_F_SUPPRESS_NLERR		0x02
> +#define RTNL_HANDLE_F_STRICT_CHK		0x04
> +	int			flags;
> +};
> +
> +#define NLMSG_TAIL(nmsg) \
> +	((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
> +
> +typedef int (*nl_ext_ack_fn_t)(const char *errmsg, uint32_t off,
> +			       const struct nlmsghdr *inner_nlh);
> +
> +int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
> +	      __attribute__((warn_unused_result));
> +void rtnl_close(struct rtnl_handle *rth);
> +int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
> +	      struct nlmsghdr **answer)
> +	      __attribute__((warn_unused_result));
> +
> +int addattr(struct nlmsghdr *n, int maxlen, int type);
> +int addattr8(struct nlmsghdr *n, int maxlen, int type, __u8 data);
> +int addattr16(struct nlmsghdr *n, int maxlen, int type, __u16 data);
> +int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data);
> +int addattr64(struct nlmsghdr *n, int maxlen, int type, __u64 data);
> +int addattrstrz(struct nlmsghdr *n, int maxlen, int type, const char *data);
> +int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data, int alen);
> +int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len);
> +struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type);
> +int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest);
> +#endif /* NETLINK_HELPERS_H */
> -- 
> 2.34.1
>
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 47365161b6fc..b8186ceb31dc 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -579,11 +579,20 @@  endef
 # Define test_progs test runner.
 TRUNNER_TESTS_DIR := prog_tests
 TRUNNER_BPF_PROGS_DIR := progs
-TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c	\
-			 network_helpers.c testing_helpers.c		\
-			 btf_helpers.c flow_dissector_load.h		\
-			 cap_helpers.c test_loader.c xsk.c disasm.c	\
-			 json_writer.c unpriv_helpers.c 		\
+TRUNNER_EXTRA_SOURCES := test_progs.c		\
+			 cgroup_helpers.c	\
+			 trace_helpers.c	\
+			 network_helpers.c	\
+			 testing_helpers.c	\
+			 btf_helpers.c		\
+			 cap_helpers.c		\
+			 unpriv_helpers.c 	\
+			 netlink_helpers.c	\
+			 test_loader.c		\
+			 xsk.c			\
+			 disasm.c		\
+			 json_writer.c 		\
+			 flow_dissector_load.h	\
 			 ip_check_defrag_frags.h
 TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko	\
 		       $(OUTPUT)/liburandom_read.so			\
diff --git a/tools/testing/selftests/bpf/netlink_helpers.c b/tools/testing/selftests/bpf/netlink_helpers.c
new file mode 100644
index 000000000000..caf36eb1d032
--- /dev/null
+++ b/tools/testing/selftests/bpf/netlink_helpers.c
@@ -0,0 +1,358 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Taken & modified from iproute2's libnetlink.c
+ * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <time.h>
+#include <sys/socket.h>
+
+#include "netlink_helpers.h"
+
+static int rcvbuf = 1024 * 1024;
+
+void rtnl_close(struct rtnl_handle *rth)
+{
+	if (rth->fd >= 0) {
+		close(rth->fd);
+		rth->fd = -1;
+	}
+}
+
+int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
+		      int protocol)
+{
+	socklen_t addr_len;
+	int sndbuf = 32768;
+	int one = 1;
+
+	memset(rth, 0, sizeof(*rth));
+	rth->proto = protocol;
+	rth->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, protocol);
+	if (rth->fd < 0) {
+		perror("Cannot open netlink socket");
+		return -1;
+	}
+	if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF,
+		       &sndbuf, sizeof(sndbuf)) < 0) {
+		perror("SO_SNDBUF");
+		goto err;
+	}
+	if (setsockopt(rth->fd, SOL_SOCKET, SO_RCVBUF,
+		       &rcvbuf, sizeof(rcvbuf)) < 0) {
+		perror("SO_RCVBUF");
+		goto err;
+	}
+
+	/* Older kernels may no support extended ACK reporting */
+	setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,
+		   &one, sizeof(one));
+
+	memset(&rth->local, 0, sizeof(rth->local));
+	rth->local.nl_family = AF_NETLINK;
+	rth->local.nl_groups = subscriptions;
+
+	if (bind(rth->fd, (struct sockaddr *)&rth->local,
+		 sizeof(rth->local)) < 0) {
+		perror("Cannot bind netlink socket");
+		goto err;
+	}
+	addr_len = sizeof(rth->local);
+	if (getsockname(rth->fd, (struct sockaddr *)&rth->local,
+			&addr_len) < 0) {
+		perror("Cannot getsockname");
+		goto err;
+	}
+	if (addr_len != sizeof(rth->local)) {
+		fprintf(stderr, "Wrong address length %d\n", addr_len);
+		goto err;
+	}
+	if (rth->local.nl_family != AF_NETLINK) {
+		fprintf(stderr, "Wrong address family %d\n",
+			rth->local.nl_family);
+		goto err;
+	}
+	rth->seq = time(NULL);
+	return 0;
+err:
+	rtnl_close(rth);
+	return -1;
+}
+
+int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
+{
+	return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
+}
+
+static int __rtnl_recvmsg(int fd, struct msghdr *msg, int flags)
+{
+	int len;
+
+	do {
+		len = recvmsg(fd, msg, flags);
+	} while (len < 0 && (errno == EINTR || errno == EAGAIN));
+	if (len < 0) {
+		fprintf(stderr, "netlink receive error %s (%d)\n",
+			strerror(errno), errno);
+		return -errno;
+	}
+	if (len == 0) {
+		fprintf(stderr, "EOF on netlink\n");
+		return -ENODATA;
+	}
+	return len;
+}
+
+static int rtnl_recvmsg(int fd, struct msghdr *msg, char **answer)
+{
+	struct iovec *iov = msg->msg_iov;
+	char *buf;
+	int len;
+
+	iov->iov_base = NULL;
+	iov->iov_len = 0;
+
+	len = __rtnl_recvmsg(fd, msg, MSG_PEEK | MSG_TRUNC);
+	if (len < 0)
+		return len;
+	if (len < 32768)
+		len = 32768;
+	buf = malloc(len);
+	if (!buf) {
+		fprintf(stderr, "malloc error: not enough buffer\n");
+		return -ENOMEM;
+	}
+	iov->iov_base = buf;
+	iov->iov_len = len;
+	len = __rtnl_recvmsg(fd, msg, 0);
+	if (len < 0) {
+		free(buf);
+		return len;
+	}
+	if (answer)
+		*answer = buf;
+	else
+		free(buf);
+	return len;
+}
+
+static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,
+			    nl_ext_ack_fn_t errfn)
+{
+	fprintf(stderr, "RTNETLINK answers: %s\n",
+		strerror(-err->error));
+}
+
+static int __rtnl_talk_iov(struct rtnl_handle *rtnl, struct iovec *iov,
+			   size_t iovlen, struct nlmsghdr **answer,
+			   bool show_rtnl_err, nl_ext_ack_fn_t errfn)
+{
+	struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
+	struct iovec riov;
+	struct msghdr msg = {
+		.msg_name	= &nladdr,
+		.msg_namelen	= sizeof(nladdr),
+		.msg_iov	= iov,
+		.msg_iovlen	= iovlen,
+	};
+	unsigned int seq = 0;
+	struct nlmsghdr *h;
+	int i, status;
+	char *buf;
+
+	for (i = 0; i < iovlen; i++) {
+		h = iov[i].iov_base;
+		h->nlmsg_seq = seq = ++rtnl->seq;
+		if (answer == NULL)
+			h->nlmsg_flags |= NLM_F_ACK;
+	}
+	status = sendmsg(rtnl->fd, &msg, 0);
+	if (status < 0) {
+		perror("Cannot talk to rtnetlink");
+		return -1;
+	}
+	/* change msg to use the response iov */
+	msg.msg_iov = &riov;
+	msg.msg_iovlen = 1;
+	i = 0;
+	while (1) {
+next:
+		status = rtnl_recvmsg(rtnl->fd, &msg, &buf);
+		++i;
+		if (status < 0)
+			return status;
+		if (msg.msg_namelen != sizeof(nladdr)) {
+			fprintf(stderr,
+				"Sender address length == %d!\n",
+				msg.msg_namelen);
+			exit(1);
+		}
+		for (h = (struct nlmsghdr *)buf; status >= sizeof(*h); ) {
+			int len = h->nlmsg_len;
+			int l = len - sizeof(*h);
+
+			if (l < 0 || len > status) {
+				if (msg.msg_flags & MSG_TRUNC) {
+					fprintf(stderr, "Truncated message!\n");
+					free(buf);
+					return -1;
+				}
+				fprintf(stderr,
+					"Malformed message: len=%d!\n",
+					len);
+				exit(1);
+			}
+			if (nladdr.nl_pid != 0 ||
+			    h->nlmsg_pid != rtnl->local.nl_pid ||
+			    h->nlmsg_seq > seq || h->nlmsg_seq < seq - iovlen) {
+				/* Don't forget to skip that message. */
+				status -= NLMSG_ALIGN(len);
+				h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
+				continue;
+			}
+			if (h->nlmsg_type == NLMSG_ERROR) {
+				struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
+				int error = err->error;
+
+				if (l < sizeof(struct nlmsgerr)) {
+					fprintf(stderr, "ERROR truncated\n");
+					free(buf);
+					return -1;
+				}
+				if (error) {
+					errno = -error;
+					if (rtnl->proto != NETLINK_SOCK_DIAG &&
+					    show_rtnl_err)
+						rtnl_talk_error(h, err, errfn);
+				}
+				if (i < iovlen) {
+					free(buf);
+					goto next;
+				}
+				if (error) {
+					free(buf);
+					return -i;
+				}
+				if (answer)
+					*answer = (struct nlmsghdr *)buf;
+				else
+					free(buf);
+				return 0;
+			}
+			if (answer) {
+				*answer = (struct nlmsghdr *)buf;
+				return 0;
+			}
+			fprintf(stderr, "Unexpected reply!\n");
+			status -= NLMSG_ALIGN(len);
+			h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
+		}
+		free(buf);
+		if (msg.msg_flags & MSG_TRUNC) {
+			fprintf(stderr, "Message truncated!\n");
+			continue;
+		}
+		if (status) {
+			fprintf(stderr, "Remnant of size %d!\n", status);
+			exit(1);
+		}
+	}
+}
+
+static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
+		       struct nlmsghdr **answer, bool show_rtnl_err,
+		       nl_ext_ack_fn_t errfn)
+{
+	struct iovec iov = {
+		.iov_base	= n,
+		.iov_len	= n->nlmsg_len,
+	};
+
+	return __rtnl_talk_iov(rtnl, &iov, 1, answer, show_rtnl_err, errfn);
+}
+
+int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
+	      struct nlmsghdr **answer)
+{
+	return __rtnl_talk(rtnl, n, answer, true, NULL);
+}
+
+int addattr(struct nlmsghdr *n, int maxlen, int type)
+{
+	return addattr_l(n, maxlen, type, NULL, 0);
+}
+
+int addattr8(struct nlmsghdr *n, int maxlen, int type, __u8 data)
+{
+	return addattr_l(n, maxlen, type, &data, sizeof(__u8));
+}
+
+int addattr16(struct nlmsghdr *n, int maxlen, int type, __u16 data)
+{
+	return addattr_l(n, maxlen, type, &data, sizeof(__u16));
+}
+
+int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
+{
+	return addattr_l(n, maxlen, type, &data, sizeof(__u32));
+}
+
+int addattr64(struct nlmsghdr *n, int maxlen, int type, __u64 data)
+{
+	return addattr_l(n, maxlen, type, &data, sizeof(__u64));
+}
+
+int addattrstrz(struct nlmsghdr *n, int maxlen, int type, const char *str)
+{
+	return addattr_l(n, maxlen, type, str, strlen(str)+1);
+}
+
+int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
+	      int alen)
+{
+	int len = RTA_LENGTH(alen);
+	struct rtattr *rta;
+
+	if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
+		fprintf(stderr, "%s: Message exceeded bound of %d\n",
+			__func__, maxlen);
+		return -1;
+	}
+	rta = NLMSG_TAIL(n);
+	rta->rta_type = type;
+	rta->rta_len = len;
+	if (alen)
+		memcpy(RTA_DATA(rta), data, alen);
+	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
+	return 0;
+}
+
+int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
+{
+	if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
+		fprintf(stderr, "%s: Message exceeded bound of %d\n",
+			__func__, maxlen);
+		return -1;
+	}
+
+	memcpy(NLMSG_TAIL(n), data, len);
+	memset((void *) NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
+	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
+	return 0;
+}
+
+struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type)
+{
+	struct rtattr *nest = NLMSG_TAIL(n);
+
+	addattr_l(n, maxlen, type, NULL, 0);
+	return nest;
+}
+
+int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest)
+{
+	nest->rta_len = (void *)NLMSG_TAIL(n) - (void *)nest;
+	return n->nlmsg_len;
+}
diff --git a/tools/testing/selftests/bpf/netlink_helpers.h b/tools/testing/selftests/bpf/netlink_helpers.h
new file mode 100644
index 000000000000..68116818a47e
--- /dev/null
+++ b/tools/testing/selftests/bpf/netlink_helpers.h
@@ -0,0 +1,46 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef NETLINK_HELPERS_H
+#define NETLINK_HELPERS_H
+
+#include <string.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+struct rtnl_handle {
+	int			fd;
+	struct sockaddr_nl	local;
+	struct sockaddr_nl	peer;
+	__u32			seq;
+	__u32			dump;
+	int			proto;
+	FILE			*dump_fp;
+#define RTNL_HANDLE_F_LISTEN_ALL_NSID		0x01
+#define RTNL_HANDLE_F_SUPPRESS_NLERR		0x02
+#define RTNL_HANDLE_F_STRICT_CHK		0x04
+	int			flags;
+};
+
+#define NLMSG_TAIL(nmsg) \
+	((struct rtattr *) (((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
+
+typedef int (*nl_ext_ack_fn_t)(const char *errmsg, uint32_t off,
+			       const struct nlmsghdr *inner_nlh);
+
+int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
+	      __attribute__((warn_unused_result));
+void rtnl_close(struct rtnl_handle *rth);
+int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
+	      struct nlmsghdr **answer)
+	      __attribute__((warn_unused_result));
+
+int addattr(struct nlmsghdr *n, int maxlen, int type);
+int addattr8(struct nlmsghdr *n, int maxlen, int type, __u8 data);
+int addattr16(struct nlmsghdr *n, int maxlen, int type, __u16 data);
+int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data);
+int addattr64(struct nlmsghdr *n, int maxlen, int type, __u64 data);
+int addattrstrz(struct nlmsghdr *n, int maxlen, int type, const char *data);
+int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data, int alen);
+int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len);
+struct rtattr *addattr_nest(struct nlmsghdr *n, int maxlen, int type);
+int addattr_nest_end(struct nlmsghdr *n, struct rtattr *nest);
+#endif /* NETLINK_HELPERS_H */