'maps' is a generic storage of different types for sharing data between kernel
and userspace.
The maps are accessed from user space via BPF syscall, which has commands:
- create a map with given id, type and attributes
map_id = bpf_map_create(int map_id, map_type, struct nlattr *attr, int len)
returns positive map id or negative error
- delete map with given map id
err = bpf_map_delete(int map_id)
returns zero or negative error
- lookup key in a given map referenced by map_id
err = bpf_map_lookup_elem(int map_id, void *key, void *value)
returns zero and stores found elem into value or negative error
- create or update key/value pair in a given map
err = bpf_map_update_elem(int map_id, void *key, void *value)
returns zero or negative error
- find and delete element by key in a given map
err = bpf_map_delete_elem(int map_id, void *key)
- iterate map elements (based on input key return next_key)
err = bpf_map_get_next_key(int map_id, void *key, void *next_key)
Signed-off-by: Alexei Starovoitov <a...@plumgrid.com>
---
include/linux/bpf.h | 6 ++
include/uapi/linux/bpf.h | 25 +++++++
kernel/bpf/syscall.c | 180 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 211 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6448b9beea89..19cd394bdbcc 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -18,6 +18,12 @@ struct bpf_map_ops {
/* funcs callable from userspace (via syscall) */
struct bpf_map *(*map_alloc)(struct nlattr *attrs[BPF_MAP_ATTR_MAX +
1]);
void (*map_free)(struct bpf_map *);
+ int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
+
+ /* funcs callable from userspace and from eBPF programs */
+ void *(*map_lookup_elem)(struct bpf_map *map, void *key);
+ int (*map_update_elem)(struct bpf_map *map, void *key, void *value);
+ int (*map_delete_elem)(struct bpf_map *map, void *key);
};
struct bpf_map {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 04374e57c290..faed2ce2d25a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -315,6 +315,31 @@ enum bpf_cmd {
* returns zero or negative error
*/
BPF_MAP_DELETE,
+
+ /* lookup key in a given map referenced by map_id
+ * err = bpf_map_lookup_elem(int map_id, void *key, void *value)
+ * returns zero and stores found elem into value
+ * or negative error
+ */
+ BPF_MAP_LOOKUP_ELEM,
+
+ /* create or update key/value pair in a given map
+ * err = bpf_map_update_elem(int map_id, void *key, void *value)
+ * returns zero or negative error
+ */
+ BPF_MAP_UPDATE_ELEM,
+
+ /* find and delete elem by key in a given map
+ * err = bpf_map_delete_elem(int map_id, void *key)
+ * returns zero or negative error
+ */
+ BPF_MAP_DELETE_ELEM,
+
+ /* lookup key in a given map and return next key
+ * err = bpf_map_get_elem(int map_id, void *key, void *next_key)
+ * returns zero and stores next key or negative error
+ */
+ BPF_MAP_GET_NEXT_KEY,
};
enum bpf_map_attributes {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b9509923b16f..1a48da23a939 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -219,6 +219,174 @@ static int map_delete(int map_id)
return 0;
}
+static int map_lookup_elem(int map_id, void __user *ukey, void __user *uvalue)
+{
+ struct bpf_map *map;
+ void *key, *value;
+ int err;
+
+ if (map_id < 0)
+ return -EINVAL;
+
+ rcu_read_lock();
+ map = idr_find(&bpf_map_id_idr, map_id);
+ err = -EINVAL;
+ if (!map)
+ goto err_unlock;
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_ATOMIC);
+ if (!key)
+ goto err_unlock;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = -ESRCH;
+ value = map->ops->map_lookup_elem(map, key);
+ if (!value)
+ goto free_key;
+
+ err = -EFAULT;
+ if (copy_to_user(uvalue, value, map->value_size) != 0)
+ goto free_key;
+
+ err = 0;
+
+free_key:
+ kfree(key);
+err_unlock:
+ rcu_read_unlock();
+ return err;
+}
+
+static int map_update_elem(int map_id, void __user *ukey, void __user *uvalue)
+{
+ struct bpf_map *map;
+ void *key, *value;
+ int err;
+
+ if (map_id < 0)
+ return -EINVAL;
+
+ rcu_read_lock();
+ map = idr_find(&bpf_map_id_idr, map_id);
+ err = -EINVAL;
+ if (!map)
+ goto err_unlock;
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_ATOMIC);
+ if (!key)
+ goto err_unlock;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = -ENOMEM;
+ value = kmalloc(map->value_size, GFP_ATOMIC);
+ if (!value)
+ goto free_key;
+
+ err = -EFAULT;
+ if (copy_from_user(value, uvalue, map->value_size) != 0)
+ goto free_value;
+
+ err = map->ops->map_update_elem(map, key, value);
+
+free_value:
+ kfree(value);
+free_key:
+ kfree(key);
+err_unlock:
+ rcu_read_unlock();
+ return err;
+}
+
+static int map_delete_elem(int map_id, void __user *ukey)
+{
+ struct bpf_map *map;
+ void *key;
+ int err;
+
+ if (map_id < 0)
+ return -EINVAL;
+
+ rcu_read_lock();
+ map = idr_find(&bpf_map_id_idr, map_id);
+ err = -EINVAL;
+ if (!map)
+ goto err_unlock;
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_ATOMIC);
+ if (!key)
+ goto err_unlock;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = map->ops->map_delete_elem(map, key);
+
+free_key:
+ kfree(key);
+err_unlock:
+ rcu_read_unlock();
+ return err;
+}
+
+static int map_get_next_key(int map_id, void __user *ukey,
+ void __user *unext_key)
+{
+ struct bpf_map *map;
+ void *key, *next_key;
+ int err;
+
+ if (map_id < 0)
+ return -EINVAL;
+
+ rcu_read_lock();
+ map = idr_find(&bpf_map_id_idr, map_id);
+ err = -EINVAL;
+ if (!map)
+ goto err_unlock;
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_ATOMIC);
+ if (!key)
+ goto err_unlock;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = -ENOMEM;
+ next_key = kmalloc(map->key_size, GFP_ATOMIC);
+ if (!next_key)
+ goto free_key;
+
+ err = map->ops->map_get_next_key(map, key, next_key);
+ if (err)
+ goto free_next_key;
+
+ err = -EFAULT;
+ if (copy_to_user(unext_key, next_key, map->key_size) != 0)
+ goto free_next_key;
+
+ err = 0;
+
+free_next_key:
+ kfree(next_key);
+free_key:
+ kfree(key);
+err_unlock:
+ rcu_read_unlock();
+ return err;
+}
+
SYSCALL_DEFINE5(bpf, int, cmd, unsigned long, arg2, unsigned long, arg3,
unsigned long, arg4, unsigned long, arg5)
{
@@ -232,6 +400,18 @@ SYSCALL_DEFINE5(bpf, int, cmd, unsigned long, arg2,
unsigned long, arg3,
case BPF_MAP_DELETE:
return map_delete((int) arg2);
+ case BPF_MAP_LOOKUP_ELEM:
+ return map_lookup_elem((int) arg2, (void __user *) arg3,
+ (void __user *) arg4);
+ case BPF_MAP_UPDATE_ELEM:
+ return map_update_elem((int) arg2, (void __user *) arg3,
+ (void __user *) arg4);
+ case BPF_MAP_DELETE_ELEM:
+ return map_delete_elem((int) arg2, (void __user *) arg3);
+
+ case BPF_MAP_GET_NEXT_KEY:
+ return map_get_next_key((int) arg2, (void __user *) arg3,
+ (void __user *) arg4);
default:
return -EINVAL;
}
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
