libbpf: add ability to guess program type based on section name

The bpf_prog_load() function will guess program type if it's not
specified explicitly. This functionality will be used to implement
loading of different programs without asking a user to specify
the program type. In first order it will be used by bpftool.

Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 51 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 5aa45f89da93..205b7822fa0a 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1721,6 +1721,45 @@ BPF_PROG_TYPE_FNS(tracepoint, BPF_PROG_TYPE_TRACEPOINT);
 BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
 BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
 
+#define BPF_PROG_SEC(string, type) { string, sizeof(string), type }
+static const struct {
+        const char *sec;
+        size_t len;
+        enum bpf_prog_type prog_type;
+} section_names[] = {
+        BPF_PROG_SEC("socket",          BPF_PROG_TYPE_SOCKET_FILTER),
+        BPF_PROG_SEC("kprobe/",         BPF_PROG_TYPE_KPROBE),
+        BPF_PROG_SEC("kretprobe/",      BPF_PROG_TYPE_KPROBE),
+        BPF_PROG_SEC("tracepoint/",     BPF_PROG_TYPE_TRACEPOINT),
+        BPF_PROG_SEC("xdp",             BPF_PROG_TYPE_XDP),
+        BPF_PROG_SEC("perf_event",      BPF_PROG_TYPE_PERF_EVENT),
+        BPF_PROG_SEC("cgroup/skb",      BPF_PROG_TYPE_CGROUP_SKB),
+        BPF_PROG_SEC("cgroup/sock",     BPF_PROG_TYPE_CGROUP_SOCK),
+        BPF_PROG_SEC("cgroup/dev",      BPF_PROG_TYPE_CGROUP_DEVICE),
+        BPF_PROG_SEC("sockops",         BPF_PROG_TYPE_SOCK_OPS),
+        BPF_PROG_SEC("sk_skb",          BPF_PROG_TYPE_SK_SKB),
+};
+#undef BPF_PROG_SEC
+
+static enum bpf_prog_type bpf_program__guess_type(struct bpf_program *prog)
+{
+        int i;
+
+        if (!prog->section_name)
+                goto err;
+
+        for (i = 0; i < ARRAY_SIZE(section_names); i++)
+                if (strncmp(prog->section_name, section_names[i].sec,
+                            section_names[i].len) == 0)
+                        return section_names[i].prog_type;
+
+err:
+        pr_warning("failed to guess program type based on section name %s\n",
+                   prog->section_name);
+
+        return BPF_PROG_TYPE_UNSPEC;
+}
+
 int bpf_map__fd(struct bpf_map *map)
 {
         return map ? map->fd : -EINVAL;
@@ -1832,6 +1871,18 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type,
                 return -ENOENT;
         }
 
+        /*
+         * If type is not specified, try to guess it based on
+         * section name.
+         */
+        if (type == BPF_PROG_TYPE_UNSPEC) {
+                type = bpf_program__guess_type(prog);
+                if (type == BPF_PROG_TYPE_UNSPEC) {
+                        bpf_object__close(obj);
+                        return -EINVAL;
+                }
+        }
+
         bpf_program__set_type(prog, type);
         err = bpf_object__load(obj);
         if (err) {