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Commit c9d29f46 authored by Mauricio Vasquez B's avatar Mauricio Vasquez B Committed by Alexei Starovoitov
Browse files

bpf/syscall: allow key to be null in map functions 



This commit adds the required logic to allow key being NULL
in case the key_size of the map is 0.

A new __bpf_copy_key function helper only copies the key from
userpsace when key_size != 0, otherwise it enforces that key must be
null.

Signed-off-by: default avatarMauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 14499160

kernel/bpf/syscall.c

+15 −4
Original line number Diff line number Diff line
@@ -651,6 +651,17 @@ int __weak bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) 
	return -ENOTSUPP;

}



static void *__bpf_copy_key(void __user *ukey, u64 key_size)

{

	if (key_size)

		return memdup_user(ukey, key_size);



	if (ukey)

		return ERR_PTR(-EINVAL);



	return NULL;

}



/* last field in 'union bpf_attr' used by this command */

#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
@@ -678,7 +689,7 @@ static int map_lookup_elem(union bpf_attr *attr) 
		goto err_put;

	}



	key = memdup_user(ukey, map->key_size);

	key = __bpf_copy_key(ukey, map->key_size);

	if (IS_ERR(key)) {

		err = PTR_ERR(key);

		goto err_put;
@@ -785,7 +796,7 @@ static int map_update_elem(union bpf_attr *attr) 
		goto err_put;

	}



	key = memdup_user(ukey, map->key_size);

	key = __bpf_copy_key(ukey, map->key_size);

	if (IS_ERR(key)) {

		err = PTR_ERR(key);

		goto err_put;
@@ -888,7 +899,7 @@ static int map_delete_elem(union bpf_attr *attr) 
		goto err_put;

	}



	key = memdup_user(ukey, map->key_size);

	key = __bpf_copy_key(ukey, map->key_size);

	if (IS_ERR(key)) {

		err = PTR_ERR(key);

		goto err_put;
@@ -941,7 +952,7 @@ static int map_get_next_key(union bpf_attr *attr) 
	}



	if (ukey) {

		key = memdup_user(ukey, map->key_size);

		key = __bpf_copy_key(ukey, map->key_size);

		if (IS_ERR(key)) {

			err = PTR_ERR(key);

			goto err_put;