pping: Remove usage of deprecated libbpf API

The libbpf API has deprecated a number of functions used by the pping
loader. While a couple of functions have simply been renamed,
bpf_object__find_program_by_title has been completely deprecated in
favor of bpf_object__find_program_by_name. Therefore, change so that
BPF programs are found based on the C function names rather than
section names.

Also remove defines of section names as they are no longer used, and
change the section names in pping_kern.c to use "tc" instead of
"classifier/ingress" and "classifier/egress".

Finally replace the flags json_format and json_ppviz in pping_config
with a single enum for the different output formats. This makes the
logic for which output format to use clearer compared to relying on
multiple (supposedly) mutually exclusive flags (and implicitly
assuming standard format if neither flag was set).

One potential concern with this commit is that it introduces some
"magical strings". In case the function names in pping_kern.c are
changed it will require multiple changes in pping.c.

Signed-off-by: Simon Sundberg <simon.sundberg@kau.se>

Author: simosund

pping/pping.c

@@ -44,6 +44,12 @@ static const char *__doc__ =
 #define MON_TO_REAL_UPDATE_FREQ                                                \
 	(1 * NS_PER_SECOND) // Update offset between CLOCK_MONOTONIC and CLOCK_REALTIME once per second
 
+enum PPING_OUTPUT_FORMAT {
+	PPING_OUTPUT_STANDARD,
+	PPING_OUTPUT_JSON,
+	PPING_OUTPUT_PPVIZ
+};
+
 /* 
  * BPF implementation of pping using libbpf
  * Uses TC-BPF for egress and XDP for ingress
@@ -71,8 +77,8 @@ struct pping_config {
 	struct bpf_tc_opts tc_egress_opts;
 	__u64 cleanup_interval;
 	char *object_path;
-	char *ingress_sec;
-	char *egress_sec;
+	char *ingress_prog;
+	char *egress_prog;
 	char *packet_map;
 	char *flow_map;
 	char *event_map;
@@ -81,8 +87,7 @@ struct pping_config {
 	int ingress_prog_id;
 	int egress_prog_id;
 	char ifname[IF_NAMESIZE];
-	bool json_format;
-	bool ppviz_format;
+	enum PPING_OUTPUT_FORMAT output_format;
 	bool force;
 	bool created_tc_hook;
 };
@@ -164,8 +169,6 @@ static int parse_arguments(int argc, char *argv[], struct pping_config *config)
 
 	config->ifindex = 0;
 	config->force = false;
-	config->json_format = false;
-	config->ppviz_format = false;
 
 	while ((opt = getopt_long(argc, argv, "hfi:r:c:F:I:", long_options,
 				  NULL)) != -1) {
@@ -207,20 +210,22 @@ static int parse_arguments(int argc, char *argv[], struct pping_config *config)
 				cleanup_interval_s * NS_PER_SECOND;
 			break;
 		case 'F':
-			if (strcmp(optarg, "json") == 0) {
-				config->json_format = true;
+			if (strcmp(optarg, "standard") == 0) {
+				config->output_format = PPING_OUTPUT_STANDARD;
+			} else if (strcmp(optarg, "json") == 0) {
+				config->output_format = PPING_OUTPUT_JSON;
 			} else if (strcmp(optarg, "ppviz") == 0) {
-				config->ppviz_format = true;
-			} else if (strcmp(optarg, "standard") != 0) {
+				config->output_format = PPING_OUTPUT_PPVIZ;
+			} else {
 				fprintf(stderr, "format must be \"standard\", \"json\" or \"ppviz\"\n");
 				return -EINVAL;
 			}
 			break;
 		case 'I':
 			if (strcmp(optarg, "xdp") == 0) {
-				config->ingress_sec = SEC_INGRESS_XDP;
+				config->ingress_prog = "pping_xdp_ingress";
 			} else if (strcmp(optarg, "tc") == 0) {
-				config->ingress_sec = SEC_INGRESS_TC;
+				config->ingress_prog = "pping_tc_ingress";
 			} else {
 				fprintf(stderr, "ingress-hook must be \"xdp\" or \"tc\"\n");
 				return -EINVAL;
@@ -281,17 +286,17 @@ static int init_rodata(struct bpf_object *obj, void *src, size_t size)
  * If sucessful, will return the positive program id of the attached.
  * On failure, will return a negative error code.
  */
-static int xdp_attach(struct bpf_object *obj, const char *sec, int ifindex,
-		      __u32 xdp_flags)
+static int xdp_attach(struct bpf_object *obj, const char *prog_name,
+		      int ifindex, __u32 xdp_flags)
 {
 	struct bpf_program *prog;
 	int prog_fd, err;
 	__u32 prog_id;
 
-	if (sec)
-		prog = bpf_object__find_program_by_title(obj, sec);
+	if (prog_name)
+		prog = bpf_object__find_program_by_name(obj, prog_name);
 	else
-		prog = bpf_program__next(NULL, obj);
+		prog = bpf_object__next_program(obj, NULL);
 
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0)
@@ -338,7 +343,7 @@ static int xdp_detach(int ifindex, __u32 xdp_flags, __u32 expected_prog_id)
  */
 static int tc_attach(struct bpf_object *obj, int ifindex,
 		     enum bpf_tc_attach_point attach_point,
-		     const char *sec, struct bpf_tc_opts *opts,
+		     const char *prog_name, struct bpf_tc_opts *opts,
 		     bool *new_hook)
 {
 	int err;
@@ -354,7 +359,7 @@ static int tc_attach(struct bpf_object *obj, int ifindex,
 		return err;
 
 	prog_fd = bpf_program__fd(
-		bpf_object__find_program_by_title(obj, sec));
+		bpf_object__find_program_by_name(obj, prog_name));
 	if (prog_fd < 0) {
 		err = prog_fd;
 		goto err_after_hook;
@@ -782,11 +787,12 @@ static int set_programs_to_load(struct bpf_object *obj,
 				struct pping_config *config)
 {
 	struct bpf_program *prog;
-	char *unload_sec = strcmp(SEC_INGRESS_XDP, config->ingress_sec) == 0 ?
-				   SEC_INGRESS_TC :
-					 SEC_INGRESS_XDP;
+	char *unload_prog =
+		strcmp(config->ingress_prog, "pping_xdp_ingress") != 0 ?
+			"pping_xdp_ingress" :
+			      "pping_tc_ingress";
 
-	prog = bpf_object__find_program_by_title(obj, unload_sec);
+	prog = bpf_object__find_program_by_name(obj, unload_prog);
 	if (libbpf_get_error(prog))
 		return libbpf_get_error(prog);
 
@@ -846,7 +852,7 @@ static int load_attach_bpfprogs(struct bpf_object **obj,
 	// Attach egress prog
 	config->egress_prog_id =
 		tc_attach(*obj, config->ifindex, BPF_TC_EGRESS,
-			  config->egress_sec, &config->tc_egress_opts,
+			  config->egress_prog, &config->tc_egress_opts,
 			  &config->created_tc_hook);
 	if (config->egress_prog_id < 0) {
 		fprintf(stderr,
@@ -857,21 +863,21 @@ static int load_attach_bpfprogs(struct bpf_object **obj,
 	}
 
 	// Attach ingress prog
-	if (strcmp(config->ingress_sec, SEC_INGRESS_XDP) == 0)
+	if (strcmp(config->ingress_prog, "pping_xdp_ingress") == 0)
 		config->ingress_prog_id =
-			xdp_attach(*obj, config->ingress_sec, config->ifindex,
+			xdp_attach(*obj, config->ingress_prog, config->ifindex,
 				   config->xdp_flags);
 	else
 		config->ingress_prog_id =
 			tc_attach(*obj, config->ifindex, BPF_TC_INGRESS,
-				  config->ingress_sec, &config->tc_ingress_opts,
-				  NULL);
+				  config->ingress_prog,
+				  &config->tc_ingress_opts, NULL);
 	if (config->ingress_prog_id < 0) {
 		fprintf(stderr,
 			"Failed attaching ingress BPF program on interface %s: %s\n",
 			config->ifname, get_libbpf_strerror(err));
 		err = config->ingress_prog_id;
-		if (strcmp(config->ingress_sec, SEC_INGRESS_XDP) == 0)
+		if (strcmp(config->ingress_prog, "pping_xdp_ingress") == 0)
 			print_xdp_error_hints(stderr, err);
 		goto ingress_err;
 	}
@@ -936,10 +942,6 @@ int main(int argc, char *argv[])
 	int err = 0, detach_err;
 	struct bpf_object *obj = NULL;
 	struct perf_buffer *pb = NULL;
-	struct perf_buffer_opts pb_opts = {
-		.sample_cb = print_event_standard,
-		.lost_cb = handle_missed_rtt_event,
-	};
 
 	DECLARE_LIBBPF_OPTS(bpf_tc_opts, tc_ingress_opts);
 	DECLARE_LIBBPF_OPTS(bpf_tc_opts, tc_egress_opts);
@@ -948,18 +950,17 @@ int main(int argc, char *argv[])
 		.bpf_config = { .rate_limit = 100 * NS_PER_MS },
 		.cleanup_interval = 1 * NS_PER_SECOND,
 		.object_path = "pping_kern.o",
-		.ingress_sec = SEC_INGRESS_XDP,
-		.egress_sec = SEC_EGRESS_TC,
+		.ingress_prog = "pping_xdp_ingress",
+		.egress_prog = "pping_tc_egress",
 		.packet_map = "packet_ts",
 		.flow_map = "flow_state",
 		.event_map = "events",
 		.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST,
 		.tc_ingress_opts = tc_ingress_opts,
 		.tc_egress_opts = tc_egress_opts,
+		.output_format = PPING_OUTPUT_STANDARD,
 	};
 
-	print_event_func = print_event_standard;
-
 	// Detect if running as root
 	if (geteuid() != 0) {
 		printf("This program must be run as root.\n");
@@ -982,12 +983,16 @@ int main(int argc, char *argv[])
 		return EXIT_FAILURE;
 	}
 
-	if (config.json_format) {
-		pb_opts.sample_cb = print_event_json;
+	switch (config.output_format) {
+	case PPING_OUTPUT_STANDARD:
+		print_event_func = print_event_standard;
+		break;
+	case PPING_OUTPUT_JSON:
 		print_event_func = print_event_json;
-	} else if (config.ppviz_format) {
-		pb_opts.sample_cb = print_event_ppviz;
+		break;
+	case PPING_OUTPUT_PPVIZ:
 		print_event_func = print_event_ppviz;
+		break;
 	}
 
 	err = load_attach_bpfprogs(&obj, &config);
@@ -1008,7 +1013,8 @@ int main(int argc, char *argv[])
 	// Set up perf buffer
 	pb = perf_buffer__new(bpf_object__find_map_fd_by_name(obj,
 							      config.event_map),
-			      PERF_BUFFER_PAGES, &pb_opts);
+			      PERF_BUFFER_PAGES, print_event_func,
+			      handle_missed_rtt_event, NULL, NULL);
 	err = libbpf_get_error(pb);
 	if (err) {
 		fprintf(stderr, "Failed to open perf buffer %s: %s\n",
@@ -1031,15 +1037,15 @@ int main(int argc, char *argv[])
 	}
 
 	// Cleanup
-	if (config.json_format && json_ctx) {
+	if (config.output_format == PPING_OUTPUT_JSON && json_ctx) {
 		jsonw_end_array(json_ctx);
 		jsonw_destroy(&json_ctx);
 	}
 
 	perf_buffer__free(pb);
 
 cleanup_attached_progs:
-	if (strcmp(config.ingress_sec, SEC_INGRESS_XDP) == 0)
+	if (strcmp(config.ingress_prog, "pping_xdp_ingress") == 0)
 		detach_err = xdp_detach(config.ifindex, config.xdp_flags,
 					config.ingress_prog_id);
 	else

pping/pping.h

@@ -6,10 +6,6 @@
 #include <linux/in6.h>
 #include <stdbool.h>
 
-#define SEC_INGRESS_XDP "xdp"
-#define SEC_INGRESS_TC "classifier/ingress"
-#define SEC_EGRESS_TC "classifier/egress"
-
 /* For the event_type members of rtt_event and flow_event */
 #define EVENT_TYPE_FLOW 1
 #define EVENT_TYPE_RTT 2

pping/pping_kern.c

@@ -405,7 +405,7 @@ static void pping_ingress(void *ctx, struct parsing_context *pctx)
 // Programs
 
 // Egress path using TC-BPF
-SEC(SEC_EGRESS_TC)
+SEC("tc")
 int pping_tc_egress(struct __sk_buff *skb)
 {
 	struct parsing_context pctx = {
@@ -422,7 +422,7 @@ int pping_tc_egress(struct __sk_buff *skb)
 }
 
 // Ingress path using TC-BPF
-SEC(SEC_INGRESS_TC)
+SEC("tc")
 int pping_tc_ingress(struct __sk_buff *skb)
 {
 	struct parsing_context pctx = {
@@ -439,7 +439,7 @@ int pping_tc_ingress(struct __sk_buff *skb)
 }
 
 // Ingress path using XDP
-SEC(SEC_INGRESS_XDP)
+SEC("xdp")
 int pping_xdp_ingress(struct xdp_md *ctx)
 {
 	struct parsing_context pctx = {