samples/bpf: Add support for SKB_MODE to set_link_xdp_fd

Based on upstream:
 3993f2cb983b ("samples/bpf: Add support for SKB_MODE to xdp1 and xdp_tx_iptunnel")
 From: David Ahern <dsa@cumulusnetworks.com>

Adjusted to use __u32 instead of signed int, as kernel commit:
 6387d0111ca4 ("samples/bpf: fix SKB_MODE flag to be a 32-bit unsigned int")

Adjust users of set_link_xdp_fd() which now takes a flag.

The --skb-mode flag XDP_FLAGS_SKB_MODE allow enabling the network stack
generic XDP mode, even on NIC that support XDP inside the driver.  This
is practical for testing the overhead associated with invoking the normal
network stack. As described in:

 kernel/Documentation/blogposts/xdp25_eval_generic_xdp_tx.rst
 http://prototype-kernel.readthedocs.io/en/latest/blogposts/xdp25_eval_generic_xdp_tx.html

The Generic XDP for normal net_device's were introduced in
 kernel commit b5cdae3291f7 ("net: Generic XDP")

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>

kernel/samples/bpf/bpf_load.c

@@ -522,7 +522,7 @@ struct ksym *ksym_search(long key)
 	return &syms[0];
 }
 
-int set_link_xdp_fd(int ifindex, int fd)
+int set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 {
 	struct sockaddr_nl sa;
 	int sock, seq = 0, len, ret = -1;
@@ -558,15 +558,28 @@ int set_link_xdp_fd(int ifindex, int fd)
 	req.nh.nlmsg_seq = ++seq;
 	req.ifinfo.ifi_family = AF_UNSPEC;
 	req.ifinfo.ifi_index = ifindex;
+
+	/* started nested attribute for XDP */
 	nla = (struct nlattr *)(((char *)&req)
 				+ NLMSG_ALIGN(req.nh.nlmsg_len));
 	nla->nla_type = NLA_F_NESTED | 43/*IFLA_XDP*/;
+	nla->nla_len = NLA_HDRLEN;
 
-	nla_xdp = (struct nlattr *)((char *)nla + NLA_HDRLEN);
+	/* add XDP fd */
+	nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
 	nla_xdp->nla_type = 1/*IFLA_XDP_FD*/;
 	nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
 	memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));
-	nla->nla_len = NLA_HDRLEN + nla_xdp->nla_len;
+	nla->nla_len += nla_xdp->nla_len;
+
+	/* if user passed in any flags, add those too */
+	if (flags) {
+		nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
+		nla_xdp->nla_type = 3/*IFLA_XDP_FLAGS*/;
+		nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags);
+		memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags));
+		nla->nla_len += nla_xdp->nla_len;
+	}
 
 	req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
 

kernel/samples/bpf/bpf_load.h

@@ -41,5 +41,12 @@ struct ksym {
 
 int load_kallsyms(void);
 struct ksym *ksym_search(long key);
-int set_link_xdp_fd(int ifindex, int fd);
+
+#ifndef XDP_FLAGS_SKB_MODE
+#define XDP_FLAGS_SKB_MODE	(2U << 0)
+/* Avail in include/uapi/linux/if_link.h
+ *  at kernel commit b5cdae3291f7 ("net: Generic XDP")
+ */
+#endif
+int set_link_xdp_fd(int ifindex, int fd, __u32 flags);
 #endif

kernel/samples/bpf/xdp_bench01_mem_access_cost_user.c

@@ -19,6 +19,7 @@ static const char *__doc__=
 #include <time.h>
 
 #include <arpa/inet.h>
+#include <linux/if_link.h>
 
 #include "bpf_load.h"
 #include "bpf_util.h"
@@ -27,6 +28,7 @@ static const char *__doc__=
 static int ifindex = -1;
 static char ifname_buf[IF_NAMESIZE];
 static char *ifname = NULL;
+static __u32 xdp_flags = 0;
 
 /* Exit return codes */
 #define EXIT_OK                 0
@@ -40,7 +42,7 @@ static void int_exit(int sig)
 		"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
 		ifindex, ifname);
 	if (ifindex > -1)
-		set_link_xdp_fd(ifindex, -1);
+		set_link_xdp_fd(ifindex, -1, xdp_flags);
 	exit(EXIT_OK);
 }
 
@@ -51,6 +53,7 @@ static const struct option long_options[] = {
 	{"action", 	required_argument,	NULL, 'a' },
 	{"readmem", 	no_argument,		NULL, 'r' },
 	{"swapmac", 	no_argument,		NULL, 'm' },
+	{"skb-mode", 	no_argument,		NULL, 'S' },
 	{0, 0, NULL,  0 }
 };
 
@@ -296,7 +299,7 @@ int main(int argc, char **argv)
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 
 	/* Parse commands line args */
-	while ((opt = getopt_long(argc, argv, "hd:s:",
+	while ((opt = getopt_long(argc, argv, "hSd:s:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
 		case 'd':
@@ -327,6 +330,9 @@ int main(int argc, char **argv)
 		case 'm':
 			touch_mem |= SWAP_MAC;
 			break;
+		case 'S':
+			xdp_flags |= XDP_FLAGS_SKB_MODE;
+			break;
 		case 'h':
 		error:
 		default:
@@ -382,7 +388,7 @@ int main(int argc, char **argv)
 	/* Remove XDP program when program is interrupted */
 	signal(SIGINT, int_exit);
 
-	if (set_link_xdp_fd(ifindex, prog_fd[0]) < 0) {
+	if (set_link_xdp_fd(ifindex, prog_fd[0], xdp_flags) < 0) {
 		fprintf(stderr, "link set xdp fd failed\n");
 		return EXIT_FAIL_XDP;
 	}

kernel/samples/bpf/xdp_bench02_drop_pattern_user.c

@@ -24,12 +24,14 @@ static const char *__doc__=
 #include <time.h>
 
 #include <arpa/inet.h>
+#include <linux/if_link.h>
 
 #include "bpf_load.h"
 #include "bpf_util.h"
 #include "libbpf.h"
 
 static int ifindex = -1;
+static __u32 xdp_flags = 0;
 static char ifname_buf[IF_NAMESIZE];
 static char *ifname = NULL;
 
@@ -45,7 +47,7 @@ static void int_exit(int sig)
 		"Interrupted: Removing XDP program on ifindex:%d device:%s\n",
 		ifindex, ifname);
 	if (ifindex > -1)
-		set_link_xdp_fd(ifindex, -1);
+		set_link_xdp_fd(ifindex, -1, xdp_flags);
 	exit(EXIT_OK);
 }
 
@@ -56,6 +58,7 @@ static const struct option long_options[] = {
 	{"pattern1", 	required_argument,	NULL, '1' },
 	{"action", 	required_argument,	NULL, 'a' },
 	{"notouch", 	no_argument,		NULL, 'n' },
+	{"skbmode", 	no_argument,		NULL, 'S' },
 	{0, 0, NULL,  0 }
 };
 
@@ -362,7 +365,7 @@ int main(int argc, char **argv)
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 
 	/* Parse commands line args */
-	while ((opt = getopt_long(argc, argv, "hd:s:",
+	while ((opt = getopt_long(argc, argv, "hSd:s:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
 		case 'd':
@@ -393,6 +396,9 @@ int main(int argc, char **argv)
 		case 'n':
 			touch_mem = NO_TOUCH;
 			break;
+		case 'S':
+			xdp_flags |= XDP_FLAGS_SKB_MODE;
+			break;
 		case 'h':
 		error:
 		default:
@@ -443,7 +449,7 @@ int main(int argc, char **argv)
 	/* Remove XDP program when program is interrupted */
 	signal(SIGINT, int_exit);
 
-	if (set_link_xdp_fd(ifindex, prog_fd[0]) < 0) {
+	if (set_link_xdp_fd(ifindex, prog_fd[0], xdp_flags) < 0) {
 		fprintf(stderr, "link set xdp fd failed\n");
 		return EXIT_FAIL_XDP;
 	}

kernel/samples/bpf/xdp_ddos01_blacklist_user.c

@@ -33,6 +33,7 @@ static const char *__doc__=
 #include <libgen.h>  /* dirname */
 
 #include <arpa/inet.h>
+#include <linux/if_link.h>
 
 #include "bpf_load.h"
 #include "bpf_util.h"
@@ -44,13 +45,13 @@ static char ifname_buf[IF_NAMESIZE];
 static char *ifname = NULL;
 static int ifindex = -1;
 
-static void remove_xdp_program(int ifindex, const char *ifname)
+static void remove_xdp_program(int ifindex, const char *ifname, __u32 xdp_flags)
 {
 	int i;
 	fprintf(stderr, "Removing XDP program on ifindex:%d device:%s\n",
 		ifindex, ifname);
 	if (ifindex > -1)
-		set_link_xdp_fd(ifindex, -1);
+		set_link_xdp_fd(ifindex, -1, xdp_flags);
 	if (unlink(file_blacklist) < 0) {
 		printf("WARN: cannot remove map file:%s err(%d):%s\n",
 		       file_blacklist, errno, strerror(errno));
@@ -77,6 +78,7 @@ static const struct option long_options[] = {
 	{"dev",		required_argument,	NULL, 'd' },
 	{"quite",	no_argument,		NULL, 'q' },
 	{"owner",	required_argument,	NULL, 'o' },
+	{"skb-mode",	no_argument,		NULL, 'S' },
 	{0, 0, NULL,  0 }
 };
 
@@ -192,20 +194,21 @@ int main(int argc, char **argv)
 {
 	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 	bool rm_xdp_prog = false;
+	struct passwd *pwd = NULL;
+	__u32 xdp_flags = 0;
 	char filename[256];
 	int longindex = 0;
 	int fd_bpf_prog;
 	uid_t owner = -1; /* -1 result in now change of owner */
 	gid_t group = -1;
-	struct passwd *pwd = NULL;
 	int res;
 	int opt;
 	int i;
 
 	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 
 	/* Parse commands line args */
-	while ((opt = getopt_long(argc, argv, "hrqd:",
+	while ((opt = getopt_long(argc, argv, "hSrqd:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
 		case 'q':
@@ -239,6 +242,9 @@ int main(int argc, char **argv)
 				goto error;
 			}
 			break;
+		case 'S':
+			xdp_flags |= XDP_FLAGS_SKB_MODE;
+			break;
 		case 'h':
 		error:
 		default:
@@ -253,7 +259,7 @@ int main(int argc, char **argv)
 		return EXIT_FAIL_OPTION;
 	}
 	if (rm_xdp_prog) {
-		remove_xdp_program(ifindex, ifname);
+		remove_xdp_program(ifindex, ifname, xdp_flags);
 		return EXIT_OK;
 	}
 	if (verbose) {
@@ -320,7 +326,7 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
-	if (set_link_xdp_fd(ifindex, prog_fd[0]) < 0) {
+	if (set_link_xdp_fd(ifindex, prog_fd[0], xdp_flags) < 0) {
 		printf("link set xdp fd failed\n");
 		return EXIT_FAIL_XDP;
 	}

kernel/samples/bpf/xdp_ttl_user.c

@@ -27,7 +27,7 @@ static void int_exit(int sig)
 	fprintf(stderr, "Interrupted: Removing XDP program on ifindex:%d\n",
 		ifindex);
 	if (ifindex > -1)
-		set_link_xdp_fd(ifindex, -1);
+		set_link_xdp_fd(ifindex, -1, 0);
 	exit(0);
 }
 
@@ -192,7 +192,7 @@ int main(int argc, char **argv)
 	/* Remove XDP program when program is interrupted */
 	signal(SIGINT, int_exit);
 
-	if (set_link_xdp_fd(ifindex, prog_fd[0]) < 0) {
+	if (set_link_xdp_fd(ifindex, prog_fd[0], 0) < 0) {
 		printf("link set xdp fd failed\n");
 		return EXIT_FAIL_XDP;
 	}