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

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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: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158515700857.92963.7052131201257841700.stgit@toke.dk
This commit is contained in:
Toke Høiland-Jørgensen 2020-03-25 18:23:28 +01:00 committed by Alexei Starovoitov
parent 50a3e678b5
commit bd5ca3ef93
3 changed files with 42 additions and 1 deletions
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8
tools/lib/bpf/libbpf.h
View File

@ -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);

1
tools/lib/bpf/libbpf.map
View File

@ -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;

34
tools/lib/bpf/netlink.c
View File

@ -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)
{