[v3,2/4] tools: bpftool: add net detach command to detach XDP on interface

[Daniel T. Lee]

By this commit, using `bpftool net detach`, the attached XDP prog can
be detached. Detaching the BPF prog will be done through libbpf
'bpf_set_link_xdp_fd' with the progfd set to -1.

Signed-off-by: Daniel T. Lee <danieltim...@gmail.com>
---
 tools/bpf/bpftool/net.c | 42 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index c05a3fac5cac..7be96acb08e0 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -343,6 +343,43 @@ static int do_attach(int argc, char **argv)
        return 0;
 }
 
+static int do_detach(int argc, char **argv)
+{
+       enum net_attach_type attach_type;
+       int progfd, ifindex, err = 0;
+
+       /* parse detach args */
+       if (!REQ_ARGS(3))
+               return -EINVAL;
+
+       attach_type = parse_attach_type(*argv);
+       if (attach_type == max_net_attach_type) {
+               p_err("invalid net attach/detach type");
+               return -EINVAL;
+       }
+
+       NEXT_ARG();
+       ifindex = net_parse_dev(&argc, &argv);
+       if (ifindex < 1)
+               return -EINVAL;
+
+       /* detach xdp prog */
+       progfd = -1;
+       if (is_prefix("xdp", attach_type_strings[attach_type]))
+               err = do_attach_detach_xdp(progfd, attach_type, ifindex, NULL);
+
+       if (err < 0) {
+               p_err("interface %s detach failed",
+                     attach_type_strings[attach_type]);
+               return err;
+       }
+
+       if (json_output)
+               jsonw_null(json_wtr);
+
+       return 0;
+}
+
 static int do_show(int argc, char **argv)
 {
        struct bpf_attach_info attach_info = {};
@@ -419,6 +456,7 @@ static int do_help(int argc, char **argv)
        fprintf(stderr,
                "Usage: %s %s { show | list } [dev <devname>]\n"
                "       %s %s attach ATTACH_TYPE PROG dev <devname> [ overwrite 
]\n"
+               "       %s %s detach ATTACH_TYPE dev <devname>\n"
                "       %s %s help\n"
                "\n"
                "       " HELP_SPEC_PROGRAM "\n"
@@ -429,7 +467,8 @@ static int do_help(int argc, char **argv)
                "      to dump program attachments. For program types\n"
                "      sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
                "      consult iproute2.\n",
-               bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2]);
+               bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],
+               bin_name, argv[-2]);
 
        return 0;
 }
@@ -438,6 +477,7 @@ static const struct cmd cmds[] = {
        { "show",       do_show },
        { "list",       do_show },
        { "attach",     do_attach },
+       { "detach",     do_detach },
        { "help",       do_help },
        { 0 }
 };
-- 
2.20.1