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libbpf: Fix probe code to return EPERM if encountered

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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: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/158927424896.2342.10402475603585742943.stgit@ebuild
This commit is contained in:
Eelco Chaudron 2020-05-12 11:04:40 +02:00 committed by Daniel Borkmann
parent 309b81f0fd
commit fd9eef1a13
1 changed files with 29 additions and 7 deletions
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36
tools/lib/bpf/libbpf.c
View file

@ -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);