bpf: add helper for copying attrs to struct bpf_map

All map types reimplement the field-by-field copy of union bpf_attr
members into struct bpf_map.  Add a helper to perform this operation.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

include/linux/bpf.h

@@ -378,6 +378,7 @@ void bpf_map_put(struct bpf_map *map);
 int bpf_map_precharge_memlock(u32 pages);
 void *bpf_map_area_alloc(size_t size, int numa_node);
 void bpf_map_area_free(void *base);
+void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr);
 
 extern int sysctl_unprivileged_bpf_disabled;
 

kernel/bpf/cpumap.c

@@ -94,13 +94,7 @@ static struct bpf_map *cpu_map_alloc(union bpf_attr *attr)
 	if (!cmap)
 		return ERR_PTR(-ENOMEM);
 
-	/* mandatory map attributes */
-	cmap->map.map_type = attr->map_type;
-	cmap->map.key_size = attr->key_size;
-	cmap->map.value_size = attr->value_size;
-	cmap->map.max_entries = attr->max_entries;
-	cmap->map.map_flags = attr->map_flags;
-	cmap->map.numa_node = bpf_map_attr_numa_node(attr);
+	bpf_map_init_from_attr(&cmap->map, attr);
 
 	/* Pre-limit array size based on NR_CPUS, not final CPU check */
 	if (cmap->map.max_entries > NR_CPUS) {

kernel/bpf/devmap.c

@@ -93,13 +93,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
 	if (!dtab)
 		return ERR_PTR(-ENOMEM);
 
-	/* mandatory map attributes */
-	dtab->map.map_type = attr->map_type;
-	dtab->map.key_size = attr->key_size;
-	dtab->map.value_size = attr->value_size;
-	dtab->map.max_entries = attr->max_entries;
-	dtab->map.map_flags = attr->map_flags;
-	dtab->map.numa_node = bpf_map_attr_numa_node(attr);
+	bpf_map_init_from_attr(&dtab->map, attr);
 
 	/* make sure page count doesn't overflow */
 	cost = (u64) dtab->map.max_entries * sizeof(struct bpf_dtab_netdev *);

kernel/bpf/hashtab.c

@@ -304,7 +304,6 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 	 */
 	bool percpu_lru = (attr->map_flags & BPF_F_NO_COMMON_LRU);
 	bool prealloc = !(attr->map_flags & BPF_F_NO_PREALLOC);
-	int numa_node = bpf_map_attr_numa_node(attr);
 	struct bpf_htab *htab;
 	int err, i;
 	u64 cost;
@@ -313,13 +312,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 	if (!htab)
 		return ERR_PTR(-ENOMEM);
 
-	/* mandatory map attributes */
-	htab->map.map_type = attr->map_type;
-	htab->map.key_size = attr->key_size;
-	htab->map.value_size = attr->value_size;
-	htab->map.max_entries = attr->max_entries;
-	htab->map.map_flags = attr->map_flags;
-	htab->map.numa_node = numa_node;
+	bpf_map_init_from_attr(&htab->map, attr);
 
 	if (percpu_lru) {
 		/* ensure each CPU's lru list has >=1 elements.

kernel/bpf/lpm_trie.c

@@ -522,12 +522,7 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr)
 		return ERR_PTR(-ENOMEM);
 
 	/* copy mandatory map attributes */
-	trie->map.map_type = attr->map_type;
-	trie->map.key_size = attr->key_size;
-	trie->map.value_size = attr->value_size;
-	trie->map.max_entries = attr->max_entries;
-	trie->map.map_flags = attr->map_flags;
-	trie->map.numa_node = bpf_map_attr_numa_node(attr);
+	bpf_map_init_from_attr(&trie->map, attr);
 	trie->data_size = attr->key_size -
 			  offsetof(struct bpf_lpm_trie_key, data);
 	trie->max_prefixlen = trie->data_size * 8;

kernel/bpf/sockmap.c

@@ -513,13 +513,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
 	if (!stab)
 		return ERR_PTR(-ENOMEM);
 
-	/* mandatory map attributes */
-	stab->map.map_type = attr->map_type;
-	stab->map.key_size = attr->key_size;
-	stab->map.value_size = attr->value_size;
-	stab->map.max_entries = attr->max_entries;
-	stab->map.map_flags = attr->map_flags;
-	stab->map.numa_node = bpf_map_attr_numa_node(attr);
+	bpf_map_init_from_attr(&stab->map, attr);
 
 	/* make sure page count doesn't overflow */
 	cost = (u64) stab->map.max_entries * sizeof(struct sock *);

kernel/bpf/stackmap.c

@@ -88,14 +88,10 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
 	if (cost >= U32_MAX - PAGE_SIZE)
 		goto free_smap;
 
-	smap->map.map_type = attr->map_type;
-	smap->map.key_size = attr->key_size;
+	bpf_map_init_from_attr(&smap->map, attr);
 	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;
-	smap->map.numa_node = bpf_map_attr_numa_node(attr);
 
 	err = bpf_map_precharge_memlock(smap->map.pages);
 	if (err)

kernel/bpf/syscall.c

@@ -143,6 +143,16 @@ void bpf_map_area_free(void *area)
 	kvfree(area);
 }
 
+void bpf_map_init_from_attr(struct bpf_map *map, union bpf_attr *attr)
+{
+	map->map_type = attr->map_type;
+	map->key_size = attr->key_size;
+	map->value_size = attr->value_size;
+	map->max_entries = attr->max_entries;
+	map->map_flags = attr->map_flags;
+	map->numa_node = bpf_map_attr_numa_node(attr);
+}
+
 int bpf_map_precharge_memlock(u32 pages)
 {
 	struct user_struct *user = get_current_user();