Commit fd9eef1a authored by Eelco Chaudron's avatar Eelco Chaudron Committed by Daniel Borkmann
Browse files

libbpf: Fix probe code to return EPERM if encountered 



When the probe code was failing for any reason ENOTSUP was returned, even
if this was due to not having enough lock space. This patch fixes this by
returning EPERM to the user application, so it can respond and increase
the RLIMIT_MEMLOCK size.

Signed-off-by: default avatarEelco Chaudron <echaudro@redhat.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/158927424896.2342.10402475603585742943.stgit@ebuild
parent 309b81f0

tools/lib/bpf/libbpf.c

+29 −7
Original line number Diff line number Diff line
@@ -3237,7 +3237,7 @@ int bpf_map__resize(struct bpf_map *map, __u32 max_entries) 
}



static int

bpf_object__probe_name(struct bpf_object *obj)

bpf_object__probe_loading(struct bpf_object *obj)

{

	struct bpf_load_program_attr attr;

	char *cp, errmsg[STRERR_BUFSIZE];
@@ -3257,15 +3257,36 @@ bpf_object__probe_name(struct bpf_object *obj) 


	ret = bpf_load_program_xattr(&attr, NULL, 0);

	if (ret < 0) {

		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));

		pr_warn("Error in %s():%s(%d). Couldn't load basic 'r0 = 0' BPF program.\n",

			__func__, cp, errno);

		return -errno;

		ret = errno;

		cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));

		pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "

			"program. Make sure your kernel supports BPF "

			"(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is "

			"set to big enough value.\n", __func__, cp, ret);

		return -ret;

	}

	close(ret);



	/* now try the same program, but with the name */

	return 0;

}



static int

bpf_object__probe_name(struct bpf_object *obj)

{

	struct bpf_load_program_attr attr;

	struct bpf_insn insns[] = {

		BPF_MOV64_IMM(BPF_REG_0, 0),

		BPF_EXIT_INSN(),

	};

	int ret;



	/* make sure loading with name 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";

	attr.name = "test";

	ret = bpf_load_program_xattr(&attr, NULL, 0);

	if (ret >= 0) {
@@ -5636,7 +5657,8 @@ int bpf_object__load_xattr(struct bpf_object_load_attr *attr) 


	obj->loaded = true;



	err = bpf_object__probe_caps(obj);

	err = bpf_object__probe_loading(obj);

	err = err ? : bpf_object__probe_caps(obj);

	err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);

	err = err ? : bpf_object__sanitize_and_load_btf(obj);

	err = err ? : bpf_object__sanitize_maps(obj);

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