Date:   Fri,  8 Jun 2018 23:00:06 +0200
From:   Tushar Dave <tushar.n.dave@...cle.com>
To:     netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        davem@...emloft.net, john.fastabend@...il.com,
        jakub.kicinski@...ronome.com, kafai@...com, rdna@...com,
        quentin.monnet@...ronome.com, brakmo@...com, acme@...hat.com
Subject: [RFC PATCH 2/3] samples/bpf: add sample RDS program

When run in server mode, the sample RDS program opens PF_RDS socket,
attaches ebpf program to RDS socket which then uses bpf_skb_next_frag
helper along with bpf tail calls to inspect skb linear and non-linear
data.

To ease testing, RDS client functionality is also added so that users
can generate RDS packet.

Run server:
[root@...71 bpf]# ./rds_skb -s 192.168.3.71
running server in a loop
transport tcp
server bound to address: 192.168.3.71 port 4000
server listening on 192.168.3.71
192.168.3.71 received a packet from 192.168.3.71 of len 8192 cmsg len 0,
on port 52287
payload contains:30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f 40 41
42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f 50 51 52 53 54 55 56 57 58 59
5a 5b 5c 5d 5e 5f 60 61 62 63 64 65 66 67 68 69 6a 6b ...
server listening on 192.168.3.71

Run client:
[root@...70 bpf]# ./rds_skb -s 192.168.3.71 -c 192.168.3.70
transport tcp
client bound to address: 192.168.3.71 port 47437
client sending 8192 byte message from 192.168.3.71 to 192.168.3.70 on
port 47437

bpf program output:
[root@...71]# cat /sys/kernel/debug/tracing/trace_pipe
          <idle>-0     [000] ..s. 218923.839673: 0: 30 31 32
          <idle>-0     [000] ..s. 218923.839682: 0: 33 34 35
          <idle>-0     [000] ..s. 218923.845133: 0: be bf c0
          <idle>-0     [000] ..s. 218923.845135: 0: c1 c2 c3
          <idle>-0     [000] ..s. 218923.850581: 0: be bf c0
          <idle>-0     [000] ..s. 218923.850582: 0: c1 c2 c3
          <idle>-0     [000] ..s. 218923.850582: 0: no more skb frag

Note: changing MTU to 9000 help assure that RDS get skb with
fragments.

Signed-off-by: Tushar Dave <tushar.n.dave@...cle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@...cle.com>
Reviewed-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
---
 samples/bpf/Makefile       |   3 +
 samples/bpf/rds_skb_kern.c |  87 +++++++++++++
 samples/bpf/rds_skb_user.c | 311 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 401 insertions(+)
 create mode 100644 samples/bpf/rds_skb_kern.c
 create mode 100644 samples/bpf/rds_skb_user.c

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 62a99ab..a05c3b2 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -51,6 +51,7 @@ hostprogs-y += cpustat
 hostprogs-y += xdp_adjust_tail
 hostprogs-y += xdpsock
 hostprogs-y += xdp_fwd
+hostprogs-y += rds_skb
 
 # Libbpf dependencies
 LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a
@@ -105,6 +106,7 @@ cpustat-objs := bpf_load.o cpustat_user.o
 xdp_adjust_tail-objs := xdp_adjust_tail_user.o
 xdpsock-objs := bpf_load.o xdpsock_user.o
 xdp_fwd-objs := bpf_load.o xdp_fwd_user.o
+rds_skb-objs := bpf_load.o rds_skb_user.o
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
@@ -160,6 +162,7 @@ always += cpustat_kern.o
 always += xdp_adjust_tail_kern.o
 always += xdpsock_kern.o
 always += xdp_fwd_kern.o
+always += rds_skb_kern.o
 
 HOSTCFLAGS += -I$(objtree)/usr/include
 HOSTCFLAGS += -I$(srctree)/tools/lib/
diff --git a/samples/bpf/rds_skb_kern.c b/samples/bpf/rds_skb_kern.c
new file mode 100644
index 0000000..c8832d4
--- /dev/null
+++ b/samples/bpf/rds_skb_kern.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/filter.h>
+#include <linux/ptrace.h>
+#include <linux/version.h>
+#include <uapi/linux/bpf.h>
+#include <linux/rds.h>
+#include "bpf_helpers.h"
+
+
+#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F
+
+#define bpf_printk(fmt, ...)				\
+({							\
+	char ____fmt[] = fmt;				\
+	bpf_trace_printk(____fmt, sizeof(____fmt),	\
+			##__VA_ARGS__);			\
+})
+
+
+struct bpf_map_def SEC("maps") jmp_table = {
+	.type = BPF_MAP_TYPE_PROG_ARRAY,
+	.key_size = sizeof(u32),
+	.value_size = sizeof(u32),
+	.max_entries = 2,
+};
+
+#define FRAG 1
+
+static inline void dump_skb(struct __sk_buff *skb)
+{
+	void *data = (void *)(long) skb->data_meta;
+	void *data_end = (void *)(long) skb->data_end;
+	unsigned char *d;
+
+	if (data + 6 > data_end)
+		return;
+
+	d = (unsigned char *)data;
+	bpf_printk("%x %x %x\n", d[0], d[1], d[2]);
+	bpf_printk("%x %x %x\n", d[3], d[4], d[5]);
+	return;
+}
+
+static void populate_skb_frags(struct __sk_buff *skb)
+{
+	int ret;
+
+	ret = bpf_next_skb_frag(skb);
+	if (ret == -ENODATA) {
+		bpf_printk("no more skb frag\n");
+		return;
+	}
+
+	bpf_tail_call(skb, &jmp_table, 1);
+}
+
+/* walk skb frag */
+
+PROG(FRAG)(struct __sk_buff *skb)
+{
+	dump_skb(skb);
+	populate_skb_frags(skb);
+	return 0;
+}
+
+SEC("socket/0")
+int main_prog(struct __sk_buff *skb)
+{
+	void *data = (void *)(long) skb->data;
+	void *data_end = (void *)(long) skb->data_end;
+	int ret;
+	unsigned char *d;
+
+	if (data + 6 > data_end) {
+		bpf_printk("out\n");
+		return 0;
+	}
+
+	d = (unsigned char *)data;
+	bpf_printk("%x %x %x\n", d[0], d[1], d[2]);
+	bpf_printk("%x %x %x\n", d[3], d[4], d[5]);
+
+	populate_skb_frags(skb);
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/samples/bpf/rds_skb_user.c b/samples/bpf/rds_skb_user.c
new file mode 100644
index 0000000..9f73dc3
--- /dev/null
+++ b/samples/bpf/rds_skb_user.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <arpa/inet.h>
+#include <assert.h>
+#include "bpf_load.h"
+#include <getopt.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include <limits.h>
+#include <linux/sockios.h>
+#include <linux/rds.h>
+#include <linux/errqueue.h>
+#include <linux/bpf.h>
+#include <strings.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#define TESTPORT	4000
+#define BUFSIZE		8192
+
+static const char *trans2str(int trans)
+{
+	switch (trans) {
+	case RDS_TRANS_TCP:
+		return ("tcp");
+	case RDS_TRANS_NONE:
+		return ("none");
+	default:
+		return ("unknown");
+	}
+}
+
+static int gettransport(int sock)
+{
+	int err;
+	char val;
+	socklen_t len = sizeof(int);
+
+	err = getsockopt(sock, SOL_RDS, SO_RDS_TRANSPORT,
+			 (char *)&val, &len);
+	if (err < 0) {
+		fprintf(stderr, "%s: getsockopt %s\n",
+			__func__, strerror(errno));
+		return err;
+	}
+	return (int)val;
+}
+
+static int settransport(int sock, int transport)
+{
+	int err;
+
+	err = setsockopt(sock, SOL_RDS, SO_RDS_TRANSPORT,
+			 (char *)&transport, sizeof(transport));
+	if (err < 0) {
+		fprintf(stderr, "could not set transport %s, %s\n",
+			trans2str(transport), strerror(errno));
+	}
+	return err;
+}
+
+static void print_sock_local_info(int fd, char *str, struct sockaddr_in *ret)
+{
+	socklen_t sin_size = sizeof(struct sockaddr_in);
+	struct sockaddr_in sin;
+	int err;
+
+	err = getsockname(fd, (struct sockaddr *)&sin, &sin_size);
+	if (err < 0) {
+		fprintf(stderr, "%s getsockname %s\n",
+			__func__, strerror(errno));
+		return;
+	}
+	printf("%s address: %s port %d\n",
+		(str ? str : ""), inet_ntoa(sin.sin_addr), ntohs(sin.sin_port));
+
+	if (ret != NULL)
+		*ret = sin;
+}
+
+static void server(char *address, in_port_t port)
+{
+	struct sockaddr_in sin, din;
+	struct msghdr msg;
+	struct iovec *iov;
+	int rc, sock;
+	char *buf;
+
+	buf = calloc(BUFSIZE, sizeof(char));
+	if (!buf) {
+		fprintf(stderr, "%s: calloc %s\n", __func__, strerror(errno));
+		return;
+	}
+
+	sock = socket(PF_RDS, SOCK_SEQPACKET, 0);
+	if (sock < 0) {
+		fprintf(stderr, "%s: socket %s\n", __func__, strerror(errno));
+		goto out;
+	}
+	if (settransport(sock, RDS_TRANS_TCP) < 0)
+		goto out;
+
+	printf("transport %s\n", trans2str(gettransport(sock)));
+
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_family = AF_INET;
+	sin.sin_addr.s_addr = inet_addr(address);
+	sin.sin_port = htons(port);
+
+	rc = bind(sock, (struct sockaddr *)&sin, sizeof(sin));
+	if (rc < 0) {
+		fprintf(stderr, "%s: bind %s\n", __func__, strerror(errno));
+		goto out;
+	}
+
+	/* attach eBPF program */
+	assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd[1],
+			  sizeof(prog_fd[0])) == 0);
+
+	print_sock_local_info(sock, "server bound to", NULL);
+
+	iov = calloc(1, sizeof(struct iovec));
+	if (!iov) {
+		fprintf(stderr, "%s: calloc %s\n", __func__, strerror(errno));
+		goto out;
+	}
+
+	while (1) {
+		memset(buf, 0, BUFSIZE);
+		iov[0].iov_base = buf;
+		iov[0].iov_len = BUFSIZE;
+
+		memset(&msg, 0, sizeof(msg));
+		msg.msg_name = &din;
+		msg.msg_namelen = sizeof(din);
+		msg.msg_iov = iov;
+		msg.msg_iovlen = 1;
+
+		printf("server listening on %s\n", inet_ntoa(sin.sin_addr));
+
+		rc = recvmsg(sock, &msg, 0);
+		if (rc < 0) {
+			fprintf(stderr, "%s: recvmsg %s\n",
+				__func__, strerror(errno));
+			break;
+		}
+
+		printf("%s received a packet from %s of len %d cmsg len %d, on port %d\n",
+			inet_ntoa(sin.sin_addr),
+			inet_ntoa(din.sin_addr),
+			(uint32_t) iov[0].iov_len,
+			(uint32_t) msg.msg_controllen,
+			ntohs(din.sin_port));
+
+		{
+			int i;
+
+			printf("payload contains:");
+			for (i = 0; i < 60; i++)
+				printf("%x ", buf[i]);
+			printf("...\n");
+		}
+	}
+	free(iov);
+out:
+	free(buf);
+}
+
+static void create_message(char *buf)
+{
+	unsigned int i;
+
+	for (i = 0; i < BUFSIZE; i++) {
+		buf[i] = i + 0x30;
+	}
+}
+
+static int build_rds_packet(struct msghdr *msg, char *buf)
+{
+	struct iovec *iov;
+
+	iov = calloc(1, sizeof(struct iovec));
+	if (!iov) {
+		fprintf(stderr, "%s: calloc %s\n", __func__, strerror(errno));
+		return -1;
+	}
+
+	msg->msg_iov = iov;
+	msg->msg_iovlen = 1;
+
+	iov[0].iov_base = buf;
+	iov[0].iov_len = BUFSIZE * sizeof(char);
+
+	return 0;
+}
+
+static void client(char *localaddr, char *remoteaddr, in_port_t server_port)
+{
+	struct sockaddr_in sin, din;
+	struct msghdr msg;
+	int rc, sock;
+	char *buf;
+
+	buf = calloc(BUFSIZE, sizeof(char));
+	if (!buf) {
+		fprintf(stderr, "%s: calloc %s\n", __func__, strerror(errno));
+		return;
+	}
+
+	create_message(buf);
+
+	sock = socket(PF_RDS, SOCK_SEQPACKET, 0);
+	if (sock < 0) {
+		fprintf(stderr, "%s: socket %s\n", __func__, strerror(errno));
+		goto out;
+	}
+
+	if (settransport(sock, RDS_TRANS_TCP) < 0)
+		goto out;
+
+	printf("transport %s\n", trans2str(gettransport(sock)));
+
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_family = AF_INET;
+	sin.sin_addr.s_addr = inet_addr(localaddr);
+	sin.sin_port = 0;
+
+	rc = bind(sock, (struct sockaddr *)&sin, sizeof(sin));
+	if (rc < 0) {
+		fprintf(stderr, "%s: bind %s\n", __func__, strerror(errno));
+		goto out;
+	}
+	print_sock_local_info(sock, "client bound to",  &sin);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_name = &din;
+	msg.msg_namelen = sizeof(din);
+
+	memset(&din, 0, sizeof(din));
+	din.sin_family = AF_INET;
+	din.sin_addr.s_addr = inet_addr(remoteaddr);
+	din.sin_port = htons(server_port);
+
+	rc = build_rds_packet(&msg, buf);
+	if (rc < 0)
+		goto out;
+
+	printf("client sending %d byte message from %s to %s on port %d\n",
+		(uint32_t) msg.msg_iov->iov_len, localaddr,
+		remoteaddr, ntohs(sin.sin_port));
+
+	rc = sendmsg(sock, &msg, 0);
+	if (rc < 0)
+		fprintf(stderr, "%s: sendmsg %s\n", __func__, strerror(errno));
+
+	if (msg.msg_control)
+		free(msg.msg_control);
+	if (msg.msg_iov)
+		free(msg.msg_iov);
+out:
+	free(buf);
+
+	return;
+}
+
+static void usage(char *progname)
+{
+	fprintf(stderr, "Usage %s [-s srvaddr] [-c clientaddr]\n", progname);
+}
+
+int main(int argc, char **argv)
+{
+	in_port_t server_port = TESTPORT;
+	char *serveraddr = NULL;
+	char *clientaddr = NULL;
+	char filename[256];
+	int opt;
+
+	while ((opt = getopt(argc, argv, "s:c:")) != -1) {
+		switch (opt) {
+		case 's':
+			serveraddr = optarg;
+			break;
+		case 'c':
+			clientaddr = optarg;
+			break;
+		default:
+			usage(argv[0]);
+			return 1;
+		}
+	}
+
+	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+
+	if (load_bpf_file(filename)) {
+		fprintf(stderr, "Error: load_bpf_file %s", bpf_log_buf);
+		return 1;
+	}
+
+	if (serveraddr && !clientaddr) {
+		printf("running server in a loop\n");
+		server(serveraddr, server_port);
+	} else if (serveraddr && clientaddr) {
+		client(clientaddr, serveraddr, server_port);
+	}
+
+	return 0;
+}
-- 
1.8.3.1

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