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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: Mauricio Vasquez B <mauricio.vasquez@polito.it>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Mauricio Vasquez B 2018-10-18 15:16:30 +02:00 committed by Alexei Starovoitov
parent f1a2e44a3a
commit bd513cd08f
2 changed files with 67 additions and 0 deletions
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1
include/uapi/linux/bpf.h
View File

@ -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 {

66
kernel/bpf/syscall.c
View File

@ -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;