add REDIRECT

hc

2024-10-09 05e59e5fb0064c97a1c10921ecd549f2d4a58565

 kernel/samples/bpf/xdp_adjust_tail_user.c
..
..
@@ -13,23 +13,38 @@
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 #include <stdio.h>
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 #include <stdlib.h>
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 #include <string.h>
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+#include <net/if.h>
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 #include <sys/resource.h>
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 #include <arpa/inet.h>
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 #include <netinet/ether.h>
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 #include <unistd.h>
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 #include <time.h>
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-#include "bpf/bpf.h"
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-#include "bpf/libbpf.h"
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+#include <bpf/bpf.h>
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+#include <bpf/libbpf.h>
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24
 
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 #define STATS_INTERVAL_S 2U
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+#define MAX_PCKT_SIZE 600
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 static int ifindex = -1;
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-static __u32 xdp_flags;
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+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
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+static __u32 prog_id;
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31
 
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 static void int_exit(int sig)
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 {
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-	if (ifindex > -1)
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-		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
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+	__u32 curr_prog_id = 0;
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+
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+	if (ifindex > -1) {
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+		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
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+			printf("bpf_get_link_xdp_id failed\n");
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+			exit(1);
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+		}
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+		if (prog_id == curr_prog_id)
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+			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
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+		else if (!curr_prog_id)
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+			printf("couldn't find a prog id on a given iface\n");
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+		else
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+			printf("program on interface changed, not removing\n");
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+	}
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 	exit(0);
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 }
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..
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@@ -56,10 +71,12 @@
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 	printf("Start a XDP prog which send ICMP \"packet too big\" \n"
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 		"messages if ingress packet is bigger then MAX_SIZE bytes\n");
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 	printf("Usage: %s [...]\n", cmd);
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-	printf("    -i <ifindex> Interface Index\n");
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+	printf("    -i <ifname|ifindex> Interface\n");
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 	printf("    -T <stop-after-X-seconds> Default: 0 (forever)\n");
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+	printf("    -P <MAX_PCKT_SIZE> Default: %u\n", MAX_PCKT_SIZE);
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 	printf("    -S use skb-mode\n");
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 	printf("    -N enforce native mode\n");
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+	printf("    -F force loading prog\n");
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 	printf("    -h Display this help\n");
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 }
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..
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@@ -70,12 +87,16 @@
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 		.prog_type	= BPF_PROG_TYPE_XDP,
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 	};
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 	unsigned char opt_flags[256] = {};
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+	const char *optstr = "i:T:P:SNFh";
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+	struct bpf_prog_info info = {};
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+	__u32 info_len = sizeof(info);
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 	unsigned int kill_after_s = 0;
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-	const char *optstr = "i:T:SNh";
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 	int i, prog_fd, map_fd, opt;
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 	struct bpf_object *obj;
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-	struct bpf_map *map;
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+	__u32 max_pckt_size = 0;
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+	__u32 key = 0;
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 	char filename[256];
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+	int err;
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 	for (i = 0; i < strlen(optstr); i++)
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 		if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
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@@ -85,16 +106,24 @@
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106
 
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 		switch (opt) {
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 		case 'i':
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-			ifindex = atoi(optarg);
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+			ifindex = if_nametoindex(optarg);
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+			if (!ifindex)
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+				ifindex = atoi(optarg);
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 			break;
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 		case 'T':
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 			kill_after_s = atoi(optarg);
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+			break;
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+		case 'P':
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+			max_pckt_size = atoi(optarg);
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 			break;
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 		case 'S':
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 			xdp_flags |= XDP_FLAGS_SKB_MODE;
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 			break;
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 		case 'N':
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-			xdp_flags |= XDP_FLAGS_DRV_MODE;
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+			/* default, set below */
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+			break;
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+		case 'F':
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+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
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 			break;
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 		default:
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 			usage(argv[0]);
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@@ -102,6 +131,9 @@
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 		}
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 		opt_flags[opt] = 0;
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 	}
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+
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+	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
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+		xdp_flags |= XDP_FLAGS_DRV_MODE;
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 	for (i = 0; i < strlen(optstr); i++) {
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 		if (opt_flags[(unsigned int)optstr[i]]) {
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@@ -116,21 +148,31 @@
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 		return 1;
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 	}
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+	if (!ifindex) {
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+		fprintf(stderr, "Invalid ifname\n");
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+		return 1;
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+	}
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+
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 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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 	prog_load_attr.file = filename;
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 	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
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 		return 1;
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-	map = bpf_map__next(NULL, obj);
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-	if (!map) {
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-		printf("finding a map in obj file failed\n");
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-		return 1;
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+	/* static global var 'max_pcktsz' is accessible from .data section */
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+	if (max_pckt_size) {
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+		map_fd = bpf_object__find_map_fd_by_name(obj, "xdp_adju.data");
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+		if (map_fd < 0) {
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+			printf("finding a max_pcktsz map in obj file failed\n");
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+			return 1;
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+		}
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+		bpf_map_update_elem(map_fd, &key, &max_pckt_size, BPF_ANY);
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 	}
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-	map_fd = bpf_map__fd(map);
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-	if (!prog_fd) {
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-		printf("load_bpf_file: %s\n", strerror(errno));
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+	/* fetch icmpcnt map */
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+	map_fd = bpf_object__find_map_fd_by_name(obj, "icmpcnt");
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+	if (map_fd < 0) {
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+		printf("finding a icmpcnt map in obj file failed\n");
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 		return 1;
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 	}
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@@ -142,9 +184,15 @@
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 		return 1;
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 	}
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-	poll_stats(map_fd, kill_after_s);
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+	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
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+	if (err) {
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+		printf("can't get prog info - %s\n", strerror(errno));
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+		return 1;
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+	}
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+	prog_id = info.id;
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-	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
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+	poll_stats(map_fd, kill_after_s);
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+	int_exit(0);
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 	return 0;
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 }