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authorStanislav Fomichev <sdf@google.com>2018-11-21 02:11:19 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2018-11-21 23:25:33 +0100
commit47eff61777c7b2db58805f974994713c8acbe9a6 (patch)
treef9219c583de26f8bb36e6f821ad3c15218a7de0c /tools/lib
parentlibbpf: make sure bpf headers are c++ include-able (diff)
downloadlinux-47eff61777c7b2db58805f974994713c8acbe9a6.tar.xz
linux-47eff61777c7b2db58805f974994713c8acbe9a6.zip
bpf, libbpf: introduce bpf_object__probe_caps to test BPF capabilities
It currently only checks whether kernel supports map/prog names. This capability check will be used in the next two commits to skip setting prog/map names. Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c58
1 files changed, 58 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index f022ac82e882..dffdd68b5e6b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -24,6 +24,7 @@
#include <linux/kernel.h>
#include <linux/bpf.h>
#include <linux/btf.h>
+#include <linux/filter.h>
#include <linux/list.h>
#include <linux/limits.h>
#include <linux/perf_event.h>
@@ -114,6 +115,11 @@ void libbpf_set_print(libbpf_print_fn_t warn,
# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
#endif
+struct bpf_capabilities {
+ /* v4.14: kernel support for program & map names. */
+ __u32 name:1;
+};
+
/*
* bpf_prog should be a better name but it has been used in
* linux/filter.h.
@@ -160,6 +166,8 @@ struct bpf_program {
void *func_info;
__u32 func_info_rec_size;
__u32 func_info_len;
+
+ struct bpf_capabilities *caps;
};
struct bpf_map {
@@ -221,6 +229,8 @@ struct bpf_object {
void *priv;
bpf_object_clear_priv_t clear_priv;
+ struct bpf_capabilities caps;
+
char path[];
};
#define obj_elf_valid(o) ((o)->efile.elf)
@@ -342,6 +352,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
if (err)
return err;
+ prog.caps = &obj->caps;
progs = obj->programs;
nr_progs = obj->nr_programs;
@@ -1136,6 +1147,52 @@ err_free_new_name:
}
static int
+bpf_object__probe_name(struct bpf_object *obj)
+{
+ struct bpf_load_program_attr attr;
+ char *cp, errmsg[STRERR_BUFSIZE];
+ struct bpf_insn insns[] = {
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ };
+ int ret;
+
+ /* make sure basic loading works */
+
+ memset(&attr, 0, sizeof(attr));
+ attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+ attr.insns = insns;
+ attr.insns_cnt = ARRAY_SIZE(insns);
+ attr.license = "GPL";
+
+ ret = bpf_load_program_xattr(&attr, NULL, 0);
+ if (ret < 0) {
+ cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+ pr_warning("Error in %s():%s(%d). Couldn't load basic 'r0 = 0' BPF program.\n",
+ __func__, cp, errno);
+ return -errno;
+ }
+ close(ret);
+
+ /* now try the same program, but with the name */
+
+ attr.name = "test";
+ ret = bpf_load_program_xattr(&attr, NULL, 0);
+ if (ret >= 0) {
+ obj->caps.name = 1;
+ close(ret);
+ }
+
+ return 0;
+}
+
+static int
+bpf_object__probe_caps(struct bpf_object *obj)
+{
+ return bpf_object__probe_name(obj);
+}
+
+static int
bpf_object__create_maps(struct bpf_object *obj)
{
struct bpf_create_map_attr create_attr = {};
@@ -1708,6 +1765,7 @@ int bpf_object__load(struct bpf_object *obj)
obj->loaded = true;
+ CHECK_ERR(bpf_object__probe_caps(obj), err, out);
CHECK_ERR(bpf_object__create_maps(obj), err, out);
CHECK_ERR(bpf_object__relocate(obj), err, out);
CHECK_ERR(bpf_object__load_progs(obj), err, out);