samples/bpf: Check the prog id before exiting

Check the program id within the signal handler on polling xdp samples
that were previously converted to libbpf usage. Avoid the situation of
unloading the program that was not attached by sample that is exiting.
Handle also the case where bpf_get_link_xdp_id didn't exit with an error
but the xdp program was not found on an interface.
Reported-by: NMichal Papaj <michal.papaj@intel.com>
Reported-by: NJakub Spizewski <jakub.spizewski@intel.com>
Signed-off-by: NMaciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

samples/bpf/xdp1_user.c

@@ -23,10 +23,22 @@
 
 static int ifindex;
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static __u32 prog_id;
 
 static void int_exit(int sig)
 {
-	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(1);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on a given interface\n");
+	else
+		printf("program on interface changed, not removing\n");
 	exit(0);
 }
 
@@ -74,11 +86,14 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	const char *optstr = "FSN";
 	int prog_fd, map_fd, opt;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 	char filename[256];
+	int err;
 
 	while ((opt = getopt(argc, argv, optstr)) != -1) {
 		switch (opt) {
@@ -139,6 +154,13 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	poll_stats(map_fd, 2);
 
 	return 0;

samples/bpf/xdp_adjust_tail_user.c

@@ -25,11 +25,24 @@
 
 static int ifindex = -1;
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static __u32 prog_id;
 
 static void int_exit(int sig)
 {
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on a given iface\n");
+		else
+			printf("program on interface changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -72,11 +85,14 @@ int main(int argc, char **argv)
 	};
 	unsigned char opt_flags[256] = {};
 	const char *optstr = "i:T:SNFh";
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	unsigned int kill_after_s = 0;
 	int i, prog_fd, map_fd, opt;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 	char filename[256];
+	int err;
 
 	for (i = 0; i < strlen(optstr); i++)
 		if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
@@ -146,9 +162,15 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	poll_stats(map_fd, kill_after_s);
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return 1;
+	}
+	prog_id = info.id;
 
-	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	poll_stats(map_fd, kill_after_s);
+	int_exit(0);
 
 	return 0;
 }

samples/bpf/xdp_redirect_cpu_user.c

@@ -32,6 +32,7 @@ static const char *__doc__ =
 static int ifindex = -1;
 static char ifname_buf[IF_NAMESIZE];
 static char *ifname;
+static __u32 prog_id;
 
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static int cpu_map_fd;
@@ -68,11 +69,24 @@ static const struct option long_options[] = {
 
 static void int_exit(int sig)
 {
-	fprintf(stderr,
-		"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
-		ifindex, ifname);
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(EXIT_FAIL);
+		}
+		if (prog_id == curr_prog_id) {
+			fprintf(stderr,
+				"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
+				ifindex, ifname);
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		} else if (!curr_prog_id) {
+			printf("couldn't find a prog id on a given iface\n");
+		} else {
+			printf("program on interface changed, not removing\n");
+		}
+	}
 	exit(EXIT_OK);
 }
 
@@ -608,6 +622,8 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_UNSPEC,
 	};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	bool use_separators = true;
 	bool stress_mode = false;
 	struct bpf_program *prog;
@@ -617,9 +633,9 @@ int main(int argc, char **argv)
 	int longindex = 0;
 	int interval = 2;
 	int add_cpu = -1;
+	int opt, err;
 	int prog_fd;
 	__u32 qsize;
-	int opt;
 
 	/* Notice: choosing he queue size is very important with the
 	 * ixgbe driver, because it's driver page recycling trick is
@@ -746,6 +762,13 @@ int main(int argc, char **argv)
 		return EXIT_FAIL_XDP;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	stats_poll(interval, use_separators, prog_name, stress_mode);
 	return EXIT_OK;
 }

samples/bpf/xdp_redirect_map_user.c

@@ -29,15 +29,41 @@
 static int ifindex_in;
 static int ifindex_out;
 static bool ifindex_out_xdp_dummy_attached = true;
+static __u32 prog_id;
+static __u32 dummy_prog_id;
 
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static int rxcnt_map_fd;
 
 static void int_exit(int sig)
 {
-	bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
-	if (ifindex_out_xdp_dummy_attached)
-		bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(ifindex_in, &curr_prog_id, xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(1);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on iface IN\n");
+	else
+		printf("program on iface IN changed, not removing\n");
+
+	if (ifindex_out_xdp_dummy_attached) {
+		curr_prog_id = 0;
+		if (bpf_get_link_xdp_id(ifindex_out, &curr_prog_id,
+					xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on iface OUT\n");
+		else
+			printf("program on iface OUT changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -82,6 +108,8 @@ int main(int argc, char **argv)
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
 	struct bpf_program *prog, *dummy_prog;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	int prog_fd, dummy_prog_fd;
 	const char *optstr = "FSN";
 	struct bpf_object *obj;
@@ -153,6 +181,13 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	prog_id = info.id;
+
 	/* Loading dummy XDP prog on out-device */
 	if (bpf_set_link_xdp_fd(ifindex_out, dummy_prog_fd,
 			    (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {
@@ -160,6 +195,14 @@ int main(int argc, char **argv)
 		ifindex_out_xdp_dummy_attached = false;
 	}
 
+	memset(&info, 0, sizeof(info));
+	ret = bpf_obj_get_info_by_fd(dummy_prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	dummy_prog_id = info.id;
+
 	signal(SIGINT, int_exit);
 	signal(SIGTERM, int_exit);
 

samples/bpf/xdp_redirect_user.c

@@ -29,15 +29,41 @@
 static int ifindex_in;
 static int ifindex_out;
 static bool ifindex_out_xdp_dummy_attached = true;
+static __u32 prog_id;
+static __u32 dummy_prog_id;
 
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static int rxcnt_map_fd;
 
 static void int_exit(int sig)
 {
-	bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
-	if (ifindex_out_xdp_dummy_attached)
-		bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (bpf_get_link_xdp_id(ifindex_in, &curr_prog_id, xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(1);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(ifindex_in, -1, xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on iface IN\n");
+	else
+		printf("program on iface IN changed, not removing\n");
+
+	if (ifindex_out_xdp_dummy_attached) {
+		curr_prog_id = 0;
+		if (bpf_get_link_xdp_id(ifindex_out, &curr_prog_id,
+					xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on iface OUT\n");
+		else
+			printf("program on iface OUT changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -84,6 +110,8 @@ int main(int argc, char **argv)
 	};
 	struct bpf_program *prog, *dummy_prog;
 	int prog_fd, tx_port_map_fd, opt;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	const char *optstr = "FSN";
 	struct bpf_object *obj;
 	char filename[256];
@@ -154,6 +182,13 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	prog_id = info.id;
+
 	/* Loading dummy XDP prog on out-device */
 	if (bpf_set_link_xdp_fd(ifindex_out, dummy_prog_fd,
 			    (xdp_flags | XDP_FLAGS_UPDATE_IF_NOEXIST)) < 0) {
@@ -161,6 +196,14 @@ int main(int argc, char **argv)
 		ifindex_out_xdp_dummy_attached = false;
 	}
 
+	memset(&info, 0, sizeof(info));
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return ret;
+	}
+	dummy_prog_id = info.id;
+
 	signal(SIGINT, int_exit);
 	signal(SIGTERM, int_exit);
 

samples/bpf/xdp_router_ipv4_user.c

@@ -30,7 +30,8 @@
 
 int sock, sock_arp, flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static int total_ifindex;
-int *ifindex_list;
+static int *ifindex_list;
+static __u32 *prog_id_list;
 char buf[8192];
 static int lpm_map_fd;
 static int rxcnt_map_fd;
@@ -41,23 +42,34 @@ static int tx_port_map_fd;
 static int get_route_table(int rtm_family);
 static void int_exit(int sig)
 {
+	__u32 prog_id = 0;
 	int i = 0;
 
-	for (i = 0; i < total_ifindex; i++)
-		bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
+	for (i = 0; i < total_ifindex; i++) {
+		if (bpf_get_link_xdp_id(ifindex_list[i], &prog_id, flags)) {
+			printf("bpf_get_link_xdp_id on iface %d failed\n",
+			       ifindex_list[i]);
+			exit(1);
+		}
+		if (prog_id_list[i] == prog_id)
+			bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
+		else if (!prog_id)
+			printf("couldn't find a prog id on iface %d\n",
+			       ifindex_list[i]);
+		else
+			printf("program on iface %d changed, not removing\n",
+			       ifindex_list[i]);
+		prog_id = 0;
+	}
 	exit(0);
 }
 
 static void close_and_exit(int sig)
 {
-	int i = 0;
-
 	close(sock);
 	close(sock_arp);
 
-	for (i = 0; i < total_ifindex; i++)
-		bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
-	exit(0);
+	int_exit(0);
 }
 
 /* Get the mac address of the interface given interface name */
@@ -186,13 +198,8 @@ static void read_route(struct nlmsghdr *nh, int nll)
 		route.iface_name = alloca(sizeof(char *) * IFNAMSIZ);
 		route.iface_name = if_indextoname(route.iface, route.iface_name);
 		route.mac = getmac(route.iface_name);
-		if (route.mac == -1) {
-			int i = 0;
-
-			for (i = 0; i < total_ifindex; i++)
-				bpf_set_link_xdp_fd(ifindex_list[i], -1, flags);
-			exit(0);
-		}
+		if (route.mac == -1)
+			int_exit(0);
 		assert(bpf_map_update_elem(tx_port_map_fd,
 					   &route.iface, &route.iface, 0) == 0);
 		if (rtm_family == AF_INET) {
@@ -625,12 +632,14 @@ int main(int ac, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	const char *optstr = "SF";
 	struct bpf_object *obj;
 	char filename[256];
 	char **ifname_list;
 	int prog_fd, opt;
-	int i = 1;
+	int err, i = 1;
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 	prog_load_attr.file = filename;
@@ -687,7 +696,7 @@ int main(int ac, char **argv)
 		return 1;
 	}
 
-	ifindex_list = (int *)malloc(total_ifindex * sizeof(int *));
+	ifindex_list = (int *)calloc(total_ifindex, sizeof(int *));
 	for (i = 0; i < total_ifindex; i++) {
 		ifindex_list[i] = if_nametoindex(ifname_list[i]);
 		if (!ifindex_list[i]) {
@@ -696,6 +705,7 @@ int main(int ac, char **argv)
 			return 1;
 		}
 	}
+	prog_id_list = (__u32 *)calloc(total_ifindex, sizeof(__u32 *));
 	for (i = 0; i < total_ifindex; i++) {
 		if (bpf_set_link_xdp_fd(ifindex_list[i], prog_fd, flags) < 0) {
 			printf("link set xdp fd failed\n");
@@ -706,6 +716,13 @@ int main(int ac, char **argv)
 
 			return 1;
 		}
+		err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+		if (err) {
+			printf("can't get prog info - %s\n", strerror(errno));
+			return err;
+		}
+		prog_id_list[i] = info.id;
+		memset(&info, 0, sizeof(info));
 		printf("Attached to %d\n", ifindex_list[i]);
 	}
 	signal(SIGINT, int_exit);

samples/bpf/xdp_rxq_info_user.c

@@ -29,6 +29,7 @@ static const char *__doc__ = " XDP RX-queue info extract example\n\n"
 static int ifindex = -1;
 static char ifname_buf[IF_NAMESIZE];
 static char *ifname;
+static __u32 prog_id;
 
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 
@@ -58,11 +59,24 @@ static const struct option long_options[] = {
 
 static void int_exit(int sig)
 {
-	fprintf(stderr,
-		"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
-		ifindex, ifname);
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(EXIT_FAIL);
+		}
+		if (prog_id == curr_prog_id) {
+			fprintf(stderr,
+				"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
+				ifindex, ifname);
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		} else if (!curr_prog_id) {
+			printf("couldn't find a prog id on a given iface\n");
+		} else {
+			printf("program on interface changed, not removing\n");
+		}
+	}
 	exit(EXIT_OK);
 }
 
@@ -447,6 +461,8 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	int prog_fd, map_fd, opt, err;
 	bool use_separators = true;
 	struct config cfg = { 0 };
@@ -580,6 +596,13 @@ int main(int argc, char **argv)
 		return EXIT_FAIL_XDP;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	stats_poll(interval, action, cfg_options);
 	return EXIT_OK;
 }

samples/bpf/xdp_sample_pkts_user.c

@@ -24,25 +24,49 @@ static int pmu_fds[MAX_CPUS], if_idx;
 static struct perf_event_mmap_page *headers[MAX_CPUS];
 static char *if_name;
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+static __u32 prog_id;
 
 static int do_attach(int idx, int fd, const char *name)
 {
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	int err;
 
 	err = bpf_set_link_xdp_fd(idx, fd, xdp_flags);
-	if (err < 0)
+	if (err < 0) {
 		printf("ERROR: failed to attach program to %s\n", name);
+		return err;
+	}
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
 
 	return err;
 }
 
 static int do_detach(int idx, const char *name)
 {
-	int err;
+	__u32 curr_prog_id = 0;
+	int err = 0;
 
-	err = bpf_set_link_xdp_fd(idx, -1, 0);
-	if (err < 0)
-		printf("ERROR: failed to detach program from %s\n", name);
+	err = bpf_get_link_xdp_id(idx, &curr_prog_id, 0);
+	if (err) {
+		printf("bpf_get_link_xdp_id failed\n");
+		return err;
+	}
+	if (prog_id == curr_prog_id) {
+		err = bpf_set_link_xdp_fd(idx, -1, 0);
+		if (err < 0)
+			printf("ERROR: failed to detach prog from %s\n", name);
+	} else if (!curr_prog_id) {
+		printf("couldn't find a prog id on a %s\n", name);
+	} else {
+		printf("program on interface changed, not removing\n");
+	}
 
 	return err;
 }

samples/bpf/xdp_tx_iptunnel_user.c

@@ -27,11 +27,24 @@
 static int ifindex = -1;
 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 static int rxcnt_map_fd;
+static __u32 prog_id;
 
 static void int_exit(int sig)
 {
-	if (ifindex > -1)
-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+	__u32 curr_prog_id = 0;
+
+	if (ifindex > -1) {
+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
+			printf("bpf_get_link_xdp_id failed\n");
+			exit(1);
+		}
+		if (prog_id == curr_prog_id)
+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
+		else if (!curr_prog_id)
+			printf("couldn't find a prog id on a given iface\n");
+		else
+			printf("program on interface changed, not removing\n");
+	}
 	exit(0);
 }
 
@@ -148,13 +161,15 @@ int main(int argc, char **argv)
 	int min_port = 0, max_port = 0, vip2tnl_map_fd;
 	const char *optstr = "i:a:p:s:d:m:T:P:FSNh";
 	unsigned char opt_flags[256] = {};
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	unsigned int kill_after_s = 0;
 	struct iptnl_info tnl = {};
 	struct bpf_object *obj;
 	struct vip vip = {};
 	char filename[256];
 	int opt, prog_fd;
-	int i;
+	int i, err;
 
 	tnl.family = AF_UNSPEC;
 	vip.protocol = IPPROTO_TCP;
@@ -276,6 +291,13 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (err) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return err;
+	}
+	prog_id = info.id;
+
 	poll_stats(kill_after_s);
 
 	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);

samples/bpf/xdpsock_user.c

@@ -76,6 +76,7 @@ static int opt_poll;
 static int opt_shared_packet_buffer;
 static int opt_interval = 1;
 static u32 opt_xdp_bind_flags;
+static __u32 prog_id;
 
 struct xdp_umem_uqueue {
 	u32 cached_prod;
@@ -631,9 +632,20 @@ static void *poller(void *arg)
 
 static void int_exit(int sig)
 {
+	__u32 curr_prog_id = 0;
+
 	(void)sig;
 	dump_stats();
-	bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
+	if (bpf_get_link_xdp_id(opt_ifindex, &curr_prog_id, opt_xdp_flags)) {
+		printf("bpf_get_link_xdp_id failed\n");
+		exit(EXIT_FAILURE);
+	}
+	if (prog_id == curr_prog_id)
+		bpf_set_link_xdp_fd(opt_ifindex, -1, opt_xdp_flags);
+	else if (!curr_prog_id)
+		printf("couldn't find a prog id on a given interface\n");
+	else
+		printf("program on interface changed, not removing\n");
 	exit(EXIT_SUCCESS);
 }
 
@@ -907,6 +919,8 @@ int main(int argc, char **argv)
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
 	int prog_fd, qidconf_map, xsks_map;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	struct bpf_object *obj;
 	char xdp_filename[256];
 	struct bpf_map *map;
@@ -953,6 +967,13 @@ int main(int argc, char **argv)
 		exit(EXIT_FAILURE);
 	}
 
+	ret = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
+	if (ret) {
+		printf("can't get prog info - %s\n", strerror(errno));
+		return 1;
+	}
+	prog_id = info.id;
+
 	ret = bpf_map_update_elem(qidconf_map, &key, &opt_queue, 0);
 	if (ret) {
 		fprintf(stderr, "ERROR: bpf_map_update_elem qidconf\n");