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bpf: libbpf: retry map creation without the name

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Since commit 88cda1c9da ("bpf: libbpf: Provide basic API support
to specify BPF obj name"), libbpf unconditionally sets bpf_attr->name
for maps. Pre v4.14 kernels don't know about map names and return an
error about unexpected non-zero data. Retry sys_bpf without a map
name to cover older kernels.

v2 changes:
* check for errno == EINVAL as suggested by Daniel Borkmann

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev 2018-11-19 14:49:01 -08:00 committed by Daniel Borkmann
parent 592ee43faf
commit 23499442c3
1 changed files with 10 additions and 1 deletions
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11
tools/lib/bpf/bpf.c
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@ -69,6 +69,7 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
{
__u32 name_len = create_attr->name ? strlen(create_attr->name) : 0;
union bpf_attr attr;
int ret;
memset(&attr, '\0', sizeof(attr));
@ -86,7 +87,15 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
attr.map_ifindex = create_attr->map_ifindex;
attr.inner_map_fd = create_attr->inner_map_fd;
return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
ret = sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
if (ret < 0 && errno == EINVAL && create_attr->name) {
/* Retry the same syscall, but without the name.
* Pre v4.14 kernels don't support map names.
*/
memset(attr.map_name, 0, sizeof(attr.map_name));
return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
}
return ret;
}
int bpf_create_map_node(enum bpf_map_type map_type, const char *name,