[PATCH bpf-next 02/16] bpf: array: move checks out of alloc function

[Jakub Kicinski]

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 <jakub.kicin...@netronome.com>
Reviewed-by: Quentin Monnet <quentin.mon...@netronome.com>
---
 kernel/bpf/arraymap.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 7c25426d3cf5..7f9a684e4947 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -49,26 +49,34 @@ 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);
-       struct bpf_array *array;
-       u64 array_size;
-       u32 elem_size;
 
        /* 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);
+       struct bpf_array *array;
+       u64 array_size;
+       u32 elem_size;
 
        elem_size = round_up(attr->value_size, 8);
 
@@ -296,6 +304,7 @@ 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,
@@ -306,6 +315,7 @@ 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,
@@ -314,12 +324,12 @@ 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)
@@ -443,7 +453,8 @@ 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,
@@ -530,7 +541,8 @@ 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,
@@ -561,7 +573,8 @@ 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,
@@ -579,7 +592,7 @@ 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;
@@ -636,6 +649,7 @@ 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,
-- 
2.15.1