Commit 04d58f1b authored by Lorenzo Bianconi's avatar Lorenzo Bianconi Committed by Alexei Starovoitov
Browse files

libbpf: add API to get XDP/XSK supported features 



Extend bpf_xdp_query routine in order to get XDP/XSK supported features
of netdev over route netlink interface.
Extend libbpf netlink implementation in order to support netlink_generic
protocol.

Co-developed-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Co-developed-by: default avatarMarek Majtyka <alardam@gmail.com>
Signed-off-by: default avatarMarek Majtyka <alardam@gmail.com>
Signed-off-by: default avatarLorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/a72609ef4f0de7fee5376c40dbf54ad7f13bfb8d.1675245258.git.lorenzo@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 8f166931

tools/lib/bpf/libbpf.h

+2 −1
Original line number Diff line number Diff line
@@ -1048,9 +1048,10 @@ struct bpf_xdp_query_opts { 
	__u32 hw_prog_id;	/* output */

	__u32 skb_prog_id;	/* output */

	__u8 attach_mode;	/* output */

	__u64 feature_flags;	/* output */

	size_t :0;

};

#define bpf_xdp_query_opts__last_field attach_mode

#define bpf_xdp_query_opts__last_field feature_flags



LIBBPF_API int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags,

			      const struct bpf_xdp_attach_opts *opts);

tools/lib/bpf/netlink.c

+96 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/if_ether.h>

#include <linux/pkt_cls.h>

#include <linux/rtnetlink.h>

#include <linux/netdev.h>

#include <sys/socket.h>

#include <errno.h>

#include <time.h>
@@ -39,6 +40,12 @@ struct xdp_id_md { 
	int ifindex;

	__u32 flags;

	struct xdp_link_info info;

	__u64 feature_flags;

};



struct xdp_features_md {

	int ifindex;

	__u64 flags;

};



static int libbpf_netlink_open(__u32 *nl_pid, int proto)
@@ -238,6 +245,43 @@ static int libbpf_netlink_send_recv(struct libbpf_nla_req *req, 
	return ret;

}



static int parse_genl_family_id(struct nlmsghdr *nh, libbpf_dump_nlmsg_t fn,

				void *cookie)

{

	struct genlmsghdr *gnl = NLMSG_DATA(nh);

	struct nlattr *na = (struct nlattr *)((void *)gnl + GENL_HDRLEN);

	struct nlattr *tb[CTRL_ATTR_FAMILY_ID + 1];

	__u16 *id = cookie;



	libbpf_nla_parse(tb, CTRL_ATTR_FAMILY_ID, na,

			 NLMSG_PAYLOAD(nh, sizeof(*gnl)), NULL);

	if (!tb[CTRL_ATTR_FAMILY_ID])

		return NL_CONT;



	*id = libbpf_nla_getattr_u16(tb[CTRL_ATTR_FAMILY_ID]);

	return NL_DONE;

}



static int libbpf_netlink_resolve_genl_family_id(const char *name,

						 __u16 len, __u16 *id)

{

	struct libbpf_nla_req req = {

		.nh.nlmsg_len	= NLMSG_LENGTH(GENL_HDRLEN),

		.nh.nlmsg_type	= GENL_ID_CTRL,

		.nh.nlmsg_flags	= NLM_F_REQUEST,

		.gnl.cmd	= CTRL_CMD_GETFAMILY,

		.gnl.version	= 2,

	};

	int err;



	err = nlattr_add(&req, CTRL_ATTR_FAMILY_NAME, name, len);

	if (err < 0)

		return err;



	return libbpf_netlink_send_recv(&req, NETLINK_GENERIC,

					parse_genl_family_id, NULL, id);

}



static int __bpf_set_link_xdp_fd_replace(int ifindex, int fd, int old_fd,

					 __u32 flags)

{
@@ -357,6 +401,29 @@ static int get_xdp_info(void *cookie, void *msg, struct nlattr **tb) 
	return 0;

}



static int parse_xdp_features(struct nlmsghdr *nh, libbpf_dump_nlmsg_t fn,

			      void *cookie)

{

	struct genlmsghdr *gnl = NLMSG_DATA(nh);

	struct nlattr *na = (struct nlattr *)((void *)gnl + GENL_HDRLEN);

	struct nlattr *tb[NETDEV_CMD_MAX + 1];

	struct xdp_features_md *md = cookie;

	__u32 ifindex;



	libbpf_nla_parse(tb, NETDEV_CMD_MAX, na,

			 NLMSG_PAYLOAD(nh, sizeof(*gnl)), NULL);



	if (!tb[NETDEV_A_DEV_IFINDEX] || !tb[NETDEV_A_DEV_XDP_FEATURES])

		return NL_CONT;



	ifindex = libbpf_nla_getattr_u32(tb[NETDEV_A_DEV_IFINDEX]);

	if (ifindex != md->ifindex)

		return NL_CONT;



	md->flags = libbpf_nla_getattr_u64(tb[NETDEV_A_DEV_XDP_FEATURES]);

	return NL_DONE;

}



int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts)

{

	struct libbpf_nla_req req = {
@@ -366,6 +433,10 @@ int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts) 
		.ifinfo.ifi_family = AF_PACKET,

	};

	struct xdp_id_md xdp_id = {};

	struct xdp_features_md md = {

		.ifindex = ifindex,

	};

	__u16 id;

	int err;



	if (!OPTS_VALID(opts, bpf_xdp_query_opts))
@@ -393,6 +464,31 @@ int bpf_xdp_query(int ifindex, int xdp_flags, struct bpf_xdp_query_opts *opts) 
	OPTS_SET(opts, skb_prog_id, xdp_id.info.skb_prog_id);

	OPTS_SET(opts, attach_mode, xdp_id.info.attach_mode);



	if (!OPTS_HAS(opts, feature_flags))

		return 0;



	err = libbpf_netlink_resolve_genl_family_id("netdev", sizeof("netdev"), &id);

	if (err < 0)

		return libbpf_err(err);



	memset(&req, 0, sizeof(req));

	req.nh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);

	req.nh.nlmsg_flags = NLM_F_REQUEST;

	req.nh.nlmsg_type = id;

	req.gnl.cmd = NETDEV_CMD_DEV_GET;

	req.gnl.version = 2;



	err = nlattr_add(&req, NETDEV_A_DEV_IFINDEX, &ifindex, sizeof(ifindex));

	if (err < 0)

		return err;



	err = libbpf_netlink_send_recv(&req, NETLINK_GENERIC,

				       parse_xdp_features, NULL, &md);

	if (err)

		return libbpf_err(err);



	opts->feature_flags = md.flags;



	return 0;

}

tools/lib/bpf/nlattr.h

+12 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <errno.h>

#include <linux/netlink.h>

#include <linux/rtnetlink.h>

#include <linux/genetlink.h>



/* avoid multiple definition of netlink features */

#define __LINUX_NETLINK_H
@@ -58,6 +59,7 @@ struct libbpf_nla_req { 
	union {

		struct ifinfomsg ifinfo;

		struct tcmsg tc;

		struct genlmsghdr gnl;

	};

	char buf[128];

};
@@ -89,11 +91,21 @@ static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla) 
	return *(uint8_t *)libbpf_nla_data(nla);

}



static inline uint16_t libbpf_nla_getattr_u16(const struct nlattr *nla)

{

	return *(uint16_t *)libbpf_nla_data(nla);

}



static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)

{

	return *(uint32_t *)libbpf_nla_data(nla);

}



static inline uint64_t libbpf_nla_getattr_u64(const struct nlattr *nla)

{

	return *(uint64_t *)libbpf_nla_data(nla);

}



static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)

{

	return (const char *)libbpf_nla_data(nla);