libbpf: Fail early when loading programs with unspecified type (80b2b5c3) · Commits · 戴 / test

Before this patch, a program with unspecified type (BPF_PROG_TYPE_UNSPEC) would be passed to the BPF syscall, only to have the kernel reject it with an opaque invalid argument error. This patch makes libbpf reject such programs with a nicer error message - in particular libbpf now tries to diagnose bad ELF section names at both open time and load time. Signed-off-by:

Andrei Matei <andreimatei1@gmail.com> Signed-off-by:

Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20201203043410.59699-1-andreimatei1@gmail.com

tools/lib/bpf/libbpf.c

+14 −1

Original line number	Diff line number	Diff line
		@@ -6629,6 +6629,16 @@ load_program(struct bpf_program prog, struct bpf_insn insns, int insns_cnt,
		char *log_buf = NULL;
		int btf_fd, ret;

		if (prog->type == BPF_PROG_TYPE_UNSPEC) {
		/*
		* The program type must be set. Most likely we couldn't find a proper
		* section definition at load time, and thus we didn't infer the type.
		*/
		pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n",
		prog->name, prog->sec_name);
		return -EINVAL;
		}

		if (!insns \|\| !insns_cnt)
		return -EINVAL;

		@@ -6920,9 +6930,12 @@ __bpf_object__open(const char path, const void obj_buf, size_t obj_buf_sz,

		bpf_object__for_each_program(prog, obj) {
		prog->sec_def = find_sec_def(prog->sec_name);
		if (!prog->sec_def)
		if (!prog->sec_def) {
		/* couldn't guess, but user might manually specify */
		pr_debug("prog '%s': unrecognized ELF section name '%s'\n",
		prog->name, prog->sec_name);
		continue;
		}

		if (prog->sec_def->is_sleepable)
		prog->prog_flags \|= BPF_F_SLEEPABLE;

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