Commit bd5ca3ef authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Alexei Starovoitov
Browse files

libbpf: Add function to set link XDP fd while specifying old program 



This adds a new function to set the XDP fd while specifying the FD of the
program to replace, using the newly added IFLA_XDP_EXPECTED_FD netlink
parameter. The new function uses the opts struct mechanism to be extendable
in the future.

Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158515700857.92963.7052131201257841700.stgit@toke.dk
parent 50a3e678

tools/lib/bpf/libbpf.h

+8 −0
Original line number Diff line number Diff line
@@ -444,7 +444,15 @@ struct xdp_link_info { 
	__u8 attach_mode;

};



struct bpf_xdp_set_link_opts {

	size_t sz;

	__u32 old_fd;

};

#define bpf_xdp_set_link_opts__last_field old_fd



LIBBPF_API int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);

LIBBPF_API int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,

					const struct bpf_xdp_set_link_opts *opts);

LIBBPF_API int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags);

LIBBPF_API int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,

				     size_t info_size, __u32 flags);

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -244,4 +244,5 @@ LIBBPF_0.0.8 { 
		bpf_link__pin_path;

		bpf_link__unpin;

		bpf_program__set_attach_target;

		bpf_set_link_xdp_fd_opts;

} LIBBPF_0.0.7;

tools/lib/bpf/netlink.c

+33 −1
Original line number Diff line number Diff line
@@ -132,7 +132,8 @@ done: 
	return ret;

}



int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)

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

					 __u32 flags)

{

	int sock, seq = 0, ret;

	struct nlattr *nla, *nla_xdp;
@@ -178,6 +179,14 @@ int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags) 
		nla->nla_len += nla_xdp->nla_len;

	}



	if (flags & XDP_FLAGS_REPLACE) {

		nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);

		nla_xdp->nla_type = IFLA_XDP_EXPECTED_FD;

		nla_xdp->nla_len = NLA_HDRLEN + sizeof(old_fd);

		memcpy((char *)nla_xdp + NLA_HDRLEN, &old_fd, sizeof(old_fd));

		nla->nla_len += nla_xdp->nla_len;

	}



	req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);



	if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
@@ -191,6 +200,29 @@ cleanup: 
	return ret;

}



int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,

			     const struct bpf_xdp_set_link_opts *opts)

{

	int old_fd = -1;



	if (!OPTS_VALID(opts, bpf_xdp_set_link_opts))

		return -EINVAL;



	if (OPTS_HAS(opts, old_fd)) {

		old_fd = OPTS_GET(opts, old_fd, -1);

		flags |= XDP_FLAGS_REPLACE;

	}



	return __bpf_set_link_xdp_fd_replace(ifindex, fd,

					     old_fd,

					     flags);

}



int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)

{

	return __bpf_set_link_xdp_fd_replace(ifindex, fd, 0, flags);

}



static int __dump_link_nlmsg(struct nlmsghdr *nlh,

			     libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)

{

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