libbpf: Reject static entry-point BPF programs

mainline inclusion
from mainline-5.14-rc1
commit 513f485c
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=513f485ca5163c6cba869602d076a8e2f04d1ca1

-------------------------------------------------

Detect use of static entry-point BPF programs (those with SEC() markings) and
emit error message. This is similar to
c1cccec9 ("libbpf: Reject static maps") but for BPF programs.
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210514195534.1440970-1-andrii@kernel.org
(cherry picked from commit 513f485c)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/libbpf.c

@@ -677,6 +677,11 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
 			return -LIBBPF_ERRNO__FORMAT;
 		}
 
+		if (sec_idx != obj->efile.text_shndx && GELF_ST_BIND(sym.st_info) == STB_LOCAL) {
+			pr_warn("sec '%s': program '%s' is static and not supported\n", sec_name, name);
+			return -ENOTSUP;
+		}
+
 		pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
 			 sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);