bpf: fix wrong exposure of map_flags into fdinfo for lpm

[ upstream commit a316338cb71a3260201490e615f2f6d5c0d8fb2c ]

trie_alloc() always needs to have BPF_F_NO_PREALLOC passed in via
attr->map_flags, since it does not support preallocation yet. We
check the flag, but we never copy the flag into trie->map.map_flags,
which is later on exposed into fdinfo and used by loaders such as
iproute2. Latter uses this in bpf_map_selfcheck_pinned() to test
whether a pinned map has the same spec as the one from the BPF obj
file and if not, bails out, which is currently the case for lpm
since it exposes always 0 as flags.

Also copy over flags in array_map_alloc() and stack_map_alloc().
They always have to be 0 right now, but we should make sure to not
miss to copy them over at a later point in time when we add actual
flags for them to use.

Fixes: b95a5c4db09b ("bpf: add a longest prefix match trie map implementation")
Reported-by: Jarno Rajahalme <jarno@covalent.io>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 9a1e6ed..3be357a 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -107,6 +107,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
        array->map.key_size = attr->key_size;
        array->map.value_size = attr->value_size;
        array->map.max_entries = attr->max_entries;
+       array->map.map_flags = attr->map_flags;
        array->elem_size = elem_size;
 
        if (!percpu)

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index be85191..a2a232d 100644 (file)
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -88,6 +88,7 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
        smap->map.key_size = attr->key_size;
        smap->map.value_size = value_size;
        smap->map.max_entries = attr->max_entries;
+       smap->map.map_flags = attr->map_flags;
        smap->n_buckets = n_buckets;
        smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;