Re: [RFC PATCH bpf-next 1/5] bpf: Add link support for sk_msg prog

[Jiri Olsa <olsajiri@gmail.com>]

On Tue, Mar 05, 2024 at 12:22:00PM -0800, Yonghong Song wrote:

SNIP

> +
> +int bpf_skmsg_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
> +{
> +	struct bpf_link_primer link_primer;
> +	struct bpf_skmsg_link *skmsg_link;
> +	enum bpf_attach_type attach_type;
> +	struct bpf_map *map;
> +	int ret;
> +
> +	if (attr->link_create.flags)
> +		return -EINVAL;
> +
> +	map = bpf_map_get_with_uref(attr->link_create.target_fd);
> +	if (IS_ERR(map))
> +		return PTR_ERR(map);
> +
> +	skmsg_link = kzalloc(sizeof(*skmsg_link), GFP_USER);
> +	if (!skmsg_link) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	attach_type = attr->link_create.attach_type;
> +	bpf_link_init(&skmsg_link->link, BPF_LINK_TYPE_SK_MSG, &bpf_skmsg_link_ops, prog);
> +	skmsg_link->map = map;
> +	skmsg_link->attach_type = attach_type;
> +
> +	ret = bpf_link_prime(&skmsg_link->link, &link_primer);
> +	if (ret) {
> +		kfree(skmsg_link);
> +		goto out;
> +	}
> +
> +	ret = sock_map_prog_update(map, prog, NULL, attach_type);
> +	if (ret) {
> +		bpf_link_cleanup(&link_primer);
> +		goto out;
> +	}
> +
> +	bpf_prog_inc(prog);

there's already prog ref taken in link_create, is this needed?
also I might be missing some skmsg logic, but I can't see thi
being released

jirka

> +
> +	return bpf_link_settle(&link_primer);
> +
> +out:
> +	bpf_map_put_with_uref(map);
> +	return ret;
> +}
> diff --git a/net/core/sock_map.c b/net/core/sock_map.c
> index 27d733c0f65e..63372bc368f1 100644
> --- a/net/core/sock_map.c
> +++ b/net/core/sock_map.c
> @@ -24,8 +24,6 @@ struct bpf_stab {
>  #define SOCK_CREATE_FLAG_MASK				\
>  	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
>  
> -static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
> -				struct bpf_prog *old, u32 which);
>  static struct sk_psock_progs *sock_map_progs(struct bpf_map *map);
>  
>  static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
> @@ -1488,8 +1486,8 @@ static int sock_map_prog_lookup(struct bpf_map *map, struct bpf_prog ***pprog,
>  	return 0;
>  }
>  
> -static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
> -				struct bpf_prog *old, u32 which)
> +int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
> +			 struct bpf_prog *old, u32 which)
>  {
>  	struct bpf_prog **pprog;
>  	int ret;
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index a241f407c234..c7d2a5fcf37a 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1129,6 +1129,7 @@ enum bpf_link_type {
>  	BPF_LINK_TYPE_TCX = 11,
>  	BPF_LINK_TYPE_UPROBE_MULTI = 12,
>  	BPF_LINK_TYPE_NETKIT = 13,
> +	BPF_LINK_TYPE_SK_MSG = 14,
>  	__MAX_BPF_LINK_TYPE,
>  };
>  
> @@ -6699,6 +6700,10 @@ struct bpf_link_info {
>  			__u32 ifindex;
>  			__u32 attach_type;
>  		} netkit;
> +		struct {
> +			__u32 map_id;
> +			__u32 attach_type;
> +		} skmsg;
>  	};
>  } __attribute__((aligned(8)));
>  
> -- 
> 2.43.0
> 
>