tools: bpftool: add net attach command to attach XDP on interface

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 stat ted 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'.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index 67e99c5..33222ca 100644 (file)
--- 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(-err));
+               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 = {};
@@ -232,13 +352,9 @@ static int do_show(int argc, char **argv)
        char err_buf[256];
 
        if (argc == 2) {
-               if (strcmp(argv[0], "dev") != 0)
-                       usage();
-               filter_idx = if_nametoindex(argv[1]);
-               if (filter_idx == 0) {
-                       fprintf(stderr, "invalid dev name %s\n", argv[1]);
+               filter_idx = net_parse_dev(&argc, &argv);
+               if (filter_idx < 1)
                        return -1;
-               }
        } else if (argc != 0) {
                usage();
        }
@@ -305,13 +421,18 @@ 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 help\n"
+               "\n"
+               "       " HELP_SPEC_PROGRAM "\n"
+               "       ATTACH_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
+               "\n"
                "Note: Only xdp and tc attachments are supported now.\n"
                "      For progs attached to cgroups, use \"bpftool cgroup\"\n"
                "      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]);
 
        return 0;
 }
@@ -319,6 +440,7 @@ static int do_help(int argc, char **argv)
 static const struct cmd cmds[] = {
        { "show",       do_show },
        { "list",       do_show },
+       { "attach",     do_attach },
        { "help",       do_help },
        { 0 }
 };