On Mon, Aug 12, 2019 at 9:27 AM Y Song <ys114...@gmail.com> wrote:
>
> On Fri, Aug 9, 2019 at 6:35 AM Daniel T. Lee <danieltim...@gmail.com> wrote:
> >
> > By this commit, using `bpftool net attach`, user can attach XDP prog on
> > interface. New type of enum 'net_attach_type' has been made, as stated at
> > cover-letter, the meaning of 'attach' is, prog will be attached on
> > interface.
> >
> > With 'overwrite' option at argument, attached XDP program could be replaced.
> > Added new helper 'net_parse_dev' to parse the network device at argument.
> >
> > BPF prog will be attached through libbpf 'bpf_set_link_xdp_fd'.
> >
> > Signed-off-by: Daniel T. Lee <danieltim...@gmail.com>
> > ---
> > tools/bpf/bpftool/net.c | 136 +++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 129 insertions(+), 7 deletions(-)
> >
> > diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
> > index 67e99c56bc88..74cc346c36cd 100644
> > --- a/tools/bpf/bpftool/net.c
> > +++ b/tools/bpf/bpftool/net.c
> > @@ -55,6 +55,35 @@ struct bpf_attach_info {
> > __u32 flow_dissector_id;
> > };
> >
> > +enum net_attach_type {
> > + NET_ATTACH_TYPE_XDP,
> > + NET_ATTACH_TYPE_XDP_GENERIC,
> > + NET_ATTACH_TYPE_XDP_DRIVER,
> > + NET_ATTACH_TYPE_XDP_OFFLOAD,
> > +};
> > +
> > +static const char * const attach_type_strings[] = {
> > + [NET_ATTACH_TYPE_XDP] = "xdp",
> > + [NET_ATTACH_TYPE_XDP_GENERIC] = "xdpgeneric",
> > + [NET_ATTACH_TYPE_XDP_DRIVER] = "xdpdrv",
> > + [NET_ATTACH_TYPE_XDP_OFFLOAD] = "xdpoffload",
> > +};
> > +
> > +const size_t net_attach_type_size = ARRAY_SIZE(attach_type_strings);
> > +
> > +static enum net_attach_type parse_attach_type(const char *str)
> > +{
> > + enum net_attach_type type;
> > +
> > + for (type = 0; type < net_attach_type_size; type++) {
> > + if (attach_type_strings[type] &&
> > + is_prefix(str, attach_type_strings[type]))
> > + return type;
> > + }
> > +
> > + return net_attach_type_size;
> > +}
> > +
> > static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
> > {
> > struct bpf_netdev_t *netinfo = cookie;
> > @@ -223,6 +252,97 @@ static int query_flow_dissector(struct bpf_attach_info
> > *attach_info)
> > return 0;
> > }
> >
> > +static int net_parse_dev(int *argc, char ***argv)
> > +{
> > + int ifindex;
> > +
> > + if (is_prefix(**argv, "dev")) {
> > + NEXT_ARGP();
> > +
> > + ifindex = if_nametoindex(**argv);
> > + if (!ifindex)
> > + p_err("invalid devname %s", **argv);
> > +
> > + NEXT_ARGP();
> > + } else {
> > + p_err("expected 'dev', got: '%s'?", **argv);
> > + return -1;
> > + }
> > +
> > + return ifindex;
> > +}
> > +
> > +static int do_attach_detach_xdp(int progfd, enum net_attach_type
> > attach_type,
> > + int ifindex, bool overwrite)
> > +{
> > + __u32 flags = 0;
> > +
> > + if (!overwrite)
> > + flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
> > + if (attach_type == NET_ATTACH_TYPE_XDP_GENERIC)
> > + flags |= XDP_FLAGS_SKB_MODE;
> > + if (attach_type == NET_ATTACH_TYPE_XDP_DRIVER)
> > + flags |= XDP_FLAGS_DRV_MODE;
> > + if (attach_type == NET_ATTACH_TYPE_XDP_OFFLOAD)
> > + flags |= XDP_FLAGS_HW_MODE;
> > +
> > + return bpf_set_link_xdp_fd(ifindex, progfd, flags);
> > +}
> > +
> > +static int do_attach(int argc, char **argv)
> > +{
> > + enum net_attach_type attach_type;
> > + int progfd, ifindex, err = 0;
> > + bool overwrite = false;
> > +
> > + /* parse attach args */
> > + if (!REQ_ARGS(5))
> > + return -EINVAL;
> > +
> > + attach_type = parse_attach_type(*argv);
> > + if (attach_type == net_attach_type_size) {
> > + p_err("invalid net attach/detach type: %s", *argv);
> > + return -EINVAL;
> > + }
> > + NEXT_ARG();
> > +
> > + progfd = prog_parse_fd(&argc, &argv);
> > + if (progfd < 0)
> > + return -EINVAL;
> > +
> > + ifindex = net_parse_dev(&argc, &argv);
> > + if (ifindex < 1) {
> > + close(progfd);
> > + return -EINVAL;
> > + }
> > +
> > + if (argc) {
> > + if (is_prefix(*argv, "overwrite")) {
> > + overwrite = true;
> > + } else {
> > + p_err("expected 'overwrite', got: '%s'?", *argv);
> > + close(progfd);
> > + return -EINVAL;
> > + }
> > + }
> > +
> > + /* attach xdp prog */
> > + if (is_prefix("xdp", attach_type_strings[attach_type]))
> > + err = do_attach_detach_xdp(progfd, attach_type, ifindex,
> > + overwrite);
> > +
> > + if (err < 0) {
> > + p_err("interface %s attach failed: %s",
> > + attach_type_strings[attach_type], strerror(errno));
> > + return err;
> > + }
>
> I tried the below example,
>
> -bash-4.4$ sudo ./bpftool net attach x pinned /sys/fs/bpf/xdp_example
> dev v1
> -bash-4.4$ sudo ./bpftool net attach x pinned /sys/fs/bpf/xdp_example dev v1
> Kernel error message: XDP program already attached
> Error: interface xdp attach failed: Success
> -bash-4.4$
>
> It printed out "Success" as errno here is 0.
> The errno is encoded in variable err. Function bpf_set_link_xdp_fd()
> uses netlink interface to do setting. The syscall may be find (errno = 0)
> but the netlink msg may contain error code, which is returned with err.
>
> So the above strerror(errno) should be strerror(-err).
> libbpf API libbpf_strerror_r() accepts positive or negative err code which
> you could use as well here.
>
> With this issue fixed. You can add:
> Acked-by: Yonghong Song <y...@fb.com>
>
I didn't realize it would return 0 as 'errno'.
Thanks for letting me know.
I'll update to next patch.
Thank you for taking your time for the review.
> > +
> > + if (json_output)
> > + jsonw_null(json_wtr);
> > +
> > + return 0;
> > +}
> > +
> [...]
