bpf: arraymap: move checks out of alloc function

Use the new callback to perform allocation checks for array maps.
The fd maps don't need a special allocation callback, they only
need a special check callback.

Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Quentin Monnet <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>

Author: Jakub Kicinski

kernel/bpf/arraymap.c

@@ -49,27 +49,35 @@ static int bpf_array_alloc_percpu(struct bpf_array *array)
 }
 
 /* Called from syscall */
-static struct bpf_map *array_map_alloc(union bpf_attr *attr)
+static int array_map_alloc_check(union bpf_attr *attr)
 {
 	bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
 	int numa_node = bpf_map_attr_numa_node(attr);
-	u32 elem_size, index_mask, max_entries;
-	bool unpriv = !capable(CAP_SYS_ADMIN);
-	struct bpf_array *array;
-	u64 array_size, mask64;
 
 	/* check sanity of attributes */
 	if (attr->max_entries == 0 || attr->key_size != 4 ||
 	    attr->value_size == 0 ||
 	    attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
 	    (percpu && numa_node != NUMA_NO_NODE))
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 
 	if (attr->value_size > KMALLOC_MAX_SIZE)
 		/* if value_size is bigger, the user space won't be able to
 		 * access the elements.
 		 */
-		return ERR_PTR(-E2BIG);
+		return -E2BIG;
+
+	return 0;
+}
+
+static struct bpf_map *array_map_alloc(union bpf_attr *attr)
+{
+	bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
+	int numa_node = bpf_map_attr_numa_node(attr);
+	u32 elem_size, index_mask, max_entries;
+	bool unpriv = !capable(CAP_SYS_ADMIN);
+	struct bpf_array *array;
+	u64 array_size, mask64;
 
 	elem_size = round_up(attr->value_size, 8);
 
@@ -327,6 +335,7 @@ static void array_map_free(struct bpf_map *map)
 }
 
 const struct bpf_map_ops array_map_ops = {
+	.map_alloc_check = array_map_alloc_check,
 	.map_alloc = array_map_alloc,
 	.map_free = array_map_free,
 	.map_get_next_key = array_map_get_next_key,
@@ -337,6 +346,7 @@ const struct bpf_map_ops array_map_ops = {
 };
 
 const struct bpf_map_ops percpu_array_map_ops = {
+	.map_alloc_check = array_map_alloc_check,
 	.map_alloc = array_map_alloc,
 	.map_free = array_map_free,
 	.map_get_next_key = array_map_get_next_key,
@@ -345,12 +355,12 @@ const struct bpf_map_ops percpu_array_map_ops = {
 	.map_delete_elem = array_map_delete_elem,
 };
 
-static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
+static int fd_array_map_alloc_check(union bpf_attr *attr)
 {
 	/* only file descriptors can be stored in this type of map */
 	if (attr->value_size != sizeof(u32))
-		return ERR_PTR(-EINVAL);
-	return array_map_alloc(attr);
+		return -EINVAL;
+	return array_map_alloc_check(attr);
 }
 
 static void fd_array_map_free(struct bpf_map *map)
@@ -474,7 +484,8 @@ void bpf_fd_array_map_clear(struct bpf_map *map)
 }
 
 const struct bpf_map_ops prog_array_map_ops = {
-	.map_alloc = fd_array_map_alloc,
+	.map_alloc_check = fd_array_map_alloc_check,
+	.map_alloc = array_map_alloc,
 	.map_free = fd_array_map_free,
 	.map_get_next_key = array_map_get_next_key,
 	.map_lookup_elem = fd_array_map_lookup_elem,
@@ -561,7 +572,8 @@ static void perf_event_fd_array_release(struct bpf_map *map,
 }
 
 const struct bpf_map_ops perf_event_array_map_ops = {
-	.map_alloc = fd_array_map_alloc,
+	.map_alloc_check = fd_array_map_alloc_check,
+	.map_alloc = array_map_alloc,
 	.map_free = fd_array_map_free,
 	.map_get_next_key = array_map_get_next_key,
 	.map_lookup_elem = fd_array_map_lookup_elem,
@@ -592,7 +604,8 @@ static void cgroup_fd_array_free(struct bpf_map *map)
 }
 
 const struct bpf_map_ops cgroup_array_map_ops = {
-	.map_alloc = fd_array_map_alloc,
+	.map_alloc_check = fd_array_map_alloc_check,
+	.map_alloc = array_map_alloc,
 	.map_free = cgroup_fd_array_free,
 	.map_get_next_key = array_map_get_next_key,
 	.map_lookup_elem = fd_array_map_lookup_elem,
@@ -610,7 +623,7 @@ static struct bpf_map *array_of_map_alloc(union bpf_attr *attr)
 	if (IS_ERR(inner_map_meta))
 		return inner_map_meta;
 
-	map = fd_array_map_alloc(attr);
+	map = array_map_alloc(attr);
 	if (IS_ERR(map)) {
 		bpf_map_meta_free(inner_map_meta);
 		return map;
@@ -673,6 +686,7 @@ static u32 array_of_map_gen_lookup(struct bpf_map *map,
 }
 
 const struct bpf_map_ops array_of_maps_map_ops = {
+	.map_alloc_check = fd_array_map_alloc_check,
 	.map_alloc = array_of_map_alloc,
 	.map_free = array_of_map_free,
 	.map_get_next_key = array_map_get_next_key,