Subject: [PATCH bpf-next 13/16] bpftool: Add support for XDP egress

From: David Ahern <[email-masked]>
Date: Mon, 20 Apr 2020 14:00:52 -0600

From: David Ahern <[email-masked]>

Add NET_ATTACH_TYPE_XDP_EGRESS and update attach_type_strings to
allow a user to specify 'xdp_egress' as the attach or detach point.

libbpf handles egress config via bpf_set_link_xdp_fd_opts, so
update do_attach_detach_xdp to use it. Specifically, the new API
requires old_fd to be set based on any currently loaded program,
so use bpf_get_link_xdp_id and bpf_get_link_xdp_egress_id to get
an fd to any existing program.

Update 'net show' command to dump egress programs.

Signed-off-by: David Ahern <[email-masked]>
---
 tools/bpf/bpftool/main.h           |  2 +-
 tools/bpf/bpftool/net.c            | 48 +++++++++++++++++++++++++++---
 tools/bpf/bpftool/netlink_dumper.c | 12 ++++++--
 tools/bpf/bpftool/prog.c           |  2 +-
 4 files changed, 55 insertions(+), 9 deletions(-)

diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 86f14ce26fd7..cbc0cc2257eb 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -230,7 +230,7 @@ void btf_dump_linfo_json(const struct btf *btf,
 struct nlattr;
 struct ifinfomsg;
 struct tcmsg;
-int do_xdp_dump(struct ifinfomsg *ifinfo, struct nlattr **tb);
+int do_xdp_dump(struct ifinfomsg *ifinfo, struct nlattr **tb, bool egress);
 int do_filter_dump(struct tcmsg *ifinfo, struct nlattr **tb, const char *kind,
 		   const char *devname, int ifindex);
 
diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index c5e3895b7c8b..d09272a53734 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -32,6 +32,7 @@ struct bpf_netdev_t {
 	int	used_len;
 	int	array_len;
 	int	filter_idx;
+	bool	egress;
 };
 
 struct tc_kind_handle {
@@ -61,6 +62,7 @@ enum net_attach_type {
 	NET_ATTACH_TYPE_XDP_GENERIC,
 	NET_ATTACH_TYPE_XDP_DRIVER,
 	NET_ATTACH_TYPE_XDP_OFFLOAD,
+	NET_ATTACH_TYPE_XDP_EGRESS,
 };
 
 static const char * const attach_type_strings[] = {
@@ -68,6 +70,7 @@ static const char * const attach_type_strings[] = {
 	[NET_ATTACH_TYPE_XDP_GENERIC]	= "xdpgeneric",
 	[NET_ATTACH_TYPE_XDP_DRIVER]	= "xdpdrv",
 	[NET_ATTACH_TYPE_XDP_OFFLOAD]	= "xdpoffload",
+	[NET_ATTACH_TYPE_XDP_EGRESS]	= "xdp_egress",
 };
 
 const size_t net_attach_type_size = ARRAY_SIZE(attach_type_strings);
@@ -111,7 +114,7 @@ static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
 			 : "");
 	netinfo->used_len++;
 
-	return do_xdp_dump(ifinfo, tb);
+	return do_xdp_dump(ifinfo, tb, netinfo->egress);
 }
 
 static int dump_class_qdisc_nlmsg(void *cookie, void *msg, struct nlattr **tb)
@@ -276,10 +279,20 @@ static int net_parse_dev(int *argc, char ***argv)
 static int do_attach_detach_xdp(int progfd, enum net_attach_type attach_type,
 				int ifindex, bool overwrite)
 {
-	__u32 flags = 0;
+	struct bpf_xdp_set_link_opts opts;
+	__u32 flags = 0, id = 0;
+	int rc;
+
+	memset(&opts, 0, sizeof(opts));
+	opts.sz = sizeof(opts);
+	opts.old_fd = -1;
 
 	if (!overwrite)
 		flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
+
+	if (attach_type == NET_ATTACH_TYPE_XDP_EGRESS)
+		opts.egress = 1;
+
 	if (attach_type == NET_ATTACH_TYPE_XDP_GENERIC)
 		flags |= XDP_FLAGS_SKB_MODE;
 	if (attach_type == NET_ATTACH_TYPE_XDP_DRIVER)
@@ -287,7 +300,25 @@ static int do_attach_detach_xdp(int progfd, enum net_attach_type attach_type,
 	if (attach_type == NET_ATTACH_TYPE_XDP_OFFLOAD)
 		flags |= XDP_FLAGS_HW_MODE;
 
-	return bpf_set_link_xdp_fd(ifindex, progfd, flags);
+	if (opts.egress)
+		rc = bpf_get_link_xdp_egress_id(ifindex, &id, flags);
+	else
+		rc = bpf_get_link_xdp_id(ifindex, &id, flags);
+
+	if (rc) {
+		p_err("Failed to get existing prog id for device");
+		return rc;
+	}
+
+	if (id)
+		opts.old_fd = bpf_prog_get_fd_by_id(id);
+
+	rc = bpf_set_link_xdp_fd_opts(ifindex, progfd, flags, &opts);
+
+	if (opts.old_fd != -1)
+		close(opts.old_fd);
+
+	return rc;
 }
 
 static int do_attach(int argc, char **argv)
@@ -411,6 +442,7 @@ static int do_show(int argc, char **argv)
 	dev_array.used_len = 0;
 	dev_array.array_len = 0;
 	dev_array.filter_idx = filter_idx;
+	dev_array.egress = 0;
 
 	if (json_output)
 		jsonw_start_array(json_wtr);
@@ -419,6 +451,14 @@ static int do_show(int argc, char **argv)
 	ret = libbpf_nl_get_link(sock, nl_pid, dump_link_nlmsg, &dev_array);
 	NET_END_ARRAY("\n");
 
+	if (!ret) {
+		dev_array.egress = true;
+		NET_START_ARRAY("xdp_egress", "%s:\n");
+		ret = libbpf_nl_get_link(sock, nl_pid, dump_link_nlmsg,
+					 &dev_array);
+		NET_END_ARRAY("\n");
+	}
+
 	if (!ret) {
 		NET_START_ARRAY("tc", "%s:\n");
 		for (i = 0; i < dev_array.used_len; i++) {
@@ -464,7 +504,7 @@ static int do_help(int argc, char **argv)
 		"       %s %s help\n"
 		"\n"
 		"       " HELP_SPEC_PROGRAM "\n"
-		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
+		"       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload | xdp_egress}\n"
 		"\n"
 		"Note: Only xdp and tc attachments are supported now.\n"
 		"      For progs attached to cgroups, use \"bpftool cgroup\"\n"
diff --git a/tools/bpf/bpftool/netlink_dumper.c b/tools/bpf/bpftool/netlink_dumper.c
index 5f65140b003b..e4a2b6f8e50b 100644
--- a/tools/bpf/bpftool/netlink_dumper.c
+++ b/tools/bpf/bpftool/netlink_dumper.c
@@ -55,6 +55,7 @@ static int do_xdp_dump_one(struct nlattr *attr, unsigned int ifindex,
 		xdp_dump_prog_id(tb, IFLA_XDP_SKB_PROG_ID, "generic", true);
 		xdp_dump_prog_id(tb, IFLA_XDP_DRV_PROG_ID, "driver", true);
 		xdp_dump_prog_id(tb, IFLA_XDP_HW_PROG_ID, "offload", true);
+		xdp_dump_prog_id(tb, IFLA_XDP_EGRESS_CORE_PROG_ID, "core", true);
 		if (json_output)
 			jsonw_end_array(json_wtr);
 	} else if (mode == XDP_ATTACHED_DRV) {
@@ -63,18 +64,23 @@ static int do_xdp_dump_one(struct nlattr *attr, unsigned int ifindex,
 		xdp_dump_prog_id(tb, IFLA_XDP_PROG_ID, "generic", false);
 	} else if (mode == XDP_ATTACHED_HW) {
 		xdp_dump_prog_id(tb, IFLA_XDP_PROG_ID, "offload", false);
+	} else if (mode == XDP_ATTACHED_EGRESS_CORE) {
+		xdp_dump_prog_id(tb, IFLA_XDP_EGRESS_CORE_PROG_ID, "core",
+				 false);
 	}
 
 	NET_END_OBJECT_FINAL;
 	return 0;
 }
 
-int do_xdp_dump(struct ifinfomsg *ifinfo, struct nlattr **tb)
+int do_xdp_dump(struct ifinfomsg *ifinfo, struct nlattr **tb, bool egress)
 {
-	if (!tb[IFLA_XDP])
+	__u16 atype = egress ? IFLA_XDP_EGRESS : IFLA_XDP;
+
+	if (!tb[atype])
 		return 0;
 
-	return do_xdp_dump_one(tb[IFLA_XDP], ifinfo->ifi_index,
+	return do_xdp_dump_one(tb[atype], ifinfo->ifi_index,
 			       libbpf_nla_getattr_str(tb[IFLA_IFNAME]));
 }
 
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index f6a5974a7b0a..64695ccdcf9d 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -2014,7 +2014,7 @@ static int do_help(int argc, char **argv)
 		"                 cgroup/post_bind6 | cgroup/connect4 | cgroup/connect6 |\n"
 		"                 cgroup/sendmsg4 | cgroup/sendmsg6 | cgroup/recvmsg4 |\n"
 		"                 cgroup/recvmsg6 | cgroup/getsockopt | cgroup/setsockopt |\n"
-		"                 struct_ops | fentry | fexit | freplace }\n"
+		"                 struct_ops | fentry | fexit | freplace | xdp_egress }\n"
 		"       ATTACH_TYPE := { msg_verdict | stream_verdict | stream_parser |\n"
 		"                        flow_dissector }\n"
 		"       METRIC := { cycles | instructions | l1d_loads | llc_misses }\n"
-- 
2.21.1 (Apple Git-122.3)