Commit bd513cd0 authored by Mauricio Vasquez B's avatar Mauricio Vasquez B Committed by Alexei Starovoitov
Browse files

bpf: add MAP_LOOKUP_AND_DELETE_ELEM syscall 



The previous patch implemented a bpf queue/stack maps that
provided the peek/pop/push functions.  There is not a direct
relationship between those functions and the current maps
syscalls, hence a new MAP_LOOKUP_AND_DELETE_ELEM syscall is added,
this is mapped to the pop operation in the queue/stack maps
and it is still to implement in other kind of maps.

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 f1a2e44a

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ enum bpf_cmd { 
	BPF_BTF_LOAD,

	BPF_BTF_GET_FD_BY_ID,

	BPF_TASK_FD_QUERY,

	BPF_MAP_LOOKUP_AND_DELETE_ELEM,

};



enum bpf_map_type {

kernel/bpf/syscall.c

+66 −0
Original line number Diff line number Diff line
@@ -999,6 +999,69 @@ err_put: 
	return err;

}



#define BPF_MAP_LOOKUP_AND_DELETE_ELEM_LAST_FIELD value



static int map_lookup_and_delete_elem(union bpf_attr *attr)

{

	void __user *ukey = u64_to_user_ptr(attr->key);

	void __user *uvalue = u64_to_user_ptr(attr->value);

	int ufd = attr->map_fd;

	struct bpf_map *map;

	void *key, *value, *ptr;

	u32 value_size;

	struct fd f;

	int err;



	if (CHECK_ATTR(BPF_MAP_LOOKUP_AND_DELETE_ELEM))

		return -EINVAL;



	f = fdget(ufd);

	map = __bpf_map_get(f);

	if (IS_ERR(map))

		return PTR_ERR(map);



	if (!(f.file->f_mode & FMODE_CAN_WRITE)) {

		err = -EPERM;

		goto err_put;

	}



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

	if (IS_ERR(key)) {

		err = PTR_ERR(key);

		goto err_put;

	}



	value_size = map->value_size;



	err = -ENOMEM;

	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);

	if (!value)

		goto free_key;



	if (map->map_type == BPF_MAP_TYPE_QUEUE ||

	    map->map_type == BPF_MAP_TYPE_STACK) {

		err = map->ops->map_pop_elem(map, value);

	} else {

		err = -ENOTSUPP;

	}



	if (err)

		goto free_value;



	if (copy_to_user(uvalue, value, value_size) != 0)

		goto free_value;



	err = 0;



free_value:

	kfree(value);

free_key:

	kfree(key);

err_put:

	fdput(f);

	return err;

}



static const struct bpf_prog_ops * const bpf_prog_types[] = {

#define BPF_PROG_TYPE(_id, _name) \

	[_id] = & _name ## _prog_ops,
@@ -2472,6 +2535,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz 
	case BPF_TASK_FD_QUERY:

		err = bpf_task_fd_query(&attr, uattr);

		break;

	case BPF_MAP_LOOKUP_AND_DELETE_ELEM:

		err = map_lookup_and_delete_elem(&attr);

		break;

	default:

		err = -EINVAL;

		break;

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