ucode-mod-bpf: add support for keyless maps

Queue and stack maps have zero-sized keys and require a NULL key
pointer; the kernel rejects any non-NULL key with EINVAL, making
these maps unusable. Accept a null key argument on maps without a
key, mapping get() to peek, set() to push and delete() with return
to pop.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/package/utils/ucode-mod-bpf/src/bpf.c b/package/utils/ucode-mod-bpf/src/bpf.c
index c34772bff5dfea4ee1c1ebc2d98e6dc3a83e2a5d..d32c7ec45eb4800261e4626cace3e29c99da5166 100644 (file)
--- a/package/utils/ucode-mod-bpf/src/bpf.c
+++ b/package/utils/ucode-mod-bpf/src/bpf.c
@@ -369,6 +369,26 @@ uc_bpf_map_arg(uc_value_t *val, const char *kind, unsigned int size,
        err_return(EINVAL, "%s size mismatch (expected: %d)", kind, size);
 }
 
+static bool
+uc_bpf_map_key_arg(struct uc_bpf_map *map, uc_value_t *a_key, uint64_t *buf,
+                  void **key)
+{
+       if (!map->key_size) {
+               if (a_key) {
+                       set_error(EINVAL, "map has no key");
+                       return false;
+               }
+
+               *key = NULL;
+
+               return true;
+       }
+
+       *key = uc_bpf_map_arg(a_key, "key", map->key_size, buf);
+
+       return *key != NULL;
+}
+
 static bool
 uc_bpf_map_is_percpu(struct uc_bpf_map *map)
 {
@@ -488,8 +508,7 @@ uc_bpf_map_get(uc_vm_t *vm, size_t nargs)
        if (!map)
                err_return(EINVAL, NULL);
 
-       key = uc_bpf_map_arg(a_key, "key", map->key_size, &key_int);
-       if (!key)
+       if (!uc_bpf_map_key_arg(map, a_key, &key_int, &key))
                return NULL;
 
        if (!uc_bpf_map_val_len(map, &val_len, &num_cpus))
@@ -518,8 +537,7 @@ uc_bpf_map_set(uc_vm_t *vm, size_t nargs)
        if (!map)
                err_return(EINVAL, NULL);
 
-       key = uc_bpf_map_arg(a_key, "key", map->key_size, &key_int);
-       if (!key)
+       if (!uc_bpf_map_key_arg(map, a_key, &key_int, &key))
                return NULL;
 
        if (!uc_bpf_map_val_len(map, &val_len, &num_cpus))
@@ -558,8 +576,7 @@ uc_bpf_map_delete(uc_vm_t *vm, size_t nargs)
        if (!map)
                err_return(EINVAL, NULL);
 
-       key = uc_bpf_map_arg(a_key, "key", map->key_size, &key_int);
-       if (!key)
+       if (!uc_bpf_map_key_arg(map, a_key, &key_int, &key))
                return NULL;
 
        if (!ucv_is_truish(a_return)) {