Re: [PATCH 32/33] sctp: add sctp_sock_get_primary_addr

[Marcelo Ricardo Leitner]

On Wed, May 13, 2020 at 08:26:47AM +0200, Christoph Hellwig wrote:
> Add a helper to directly get the SCTP_PRIMARY_ADDR sockopt from kernel
> space without going through a fake uaccess.

Same comment as on the other dlm/sctp patch.

> 
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
>  fs/dlm/lowcomms.c       | 11 +++-----
>  include/net/sctp/sctp.h |  1 +
>  net/sctp/socket.c       | 57 +++++++++++++++++++++++++----------------
>  3 files changed, 39 insertions(+), 30 deletions(-)
> 
> diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
> index 6fa45365666a8..46d2d71b62c57 100644
> --- a/fs/dlm/lowcomms.c
> +++ b/fs/dlm/lowcomms.c
> @@ -855,10 +855,9 @@ static int tcp_accept_from_sock(struct connection *con)
>  static int sctp_accept_from_sock(struct connection *con)
>  {
>  	/* Check that the new node is in the lockspace */
> -	struct sctp_prim prim;
> +	struct sctp_prim prim = { };
>  	int nodeid;
> -	int prim_len, ret;
> -	int addr_len;
> +	int addr_len, ret;
>  	struct connection *newcon;
>  	struct connection *addcon;
>  	struct socket *newsock;
> @@ -876,11 +875,7 @@ static int sctp_accept_from_sock(struct connection *con)
>  	if (ret < 0)
>  		goto accept_err;
>  
> -	memset(&prim, 0, sizeof(struct sctp_prim));
> -	prim_len = sizeof(struct sctp_prim);
> -
> -	ret = kernel_getsockopt(newsock, IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
> -				(char *)&prim, &prim_len);
> +	ret = sctp_sock_get_primary_addr(con->sock->sk, &prim);
>  	if (ret < 0) {
>  		log_print("getsockopt/sctp_primary_addr failed: %d", ret);
>  		goto accept_err;
> diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
> index b505fa082f254..c98b1d14db853 100644
> --- a/include/net/sctp/sctp.h
> +++ b/include/net/sctp/sctp.h
> @@ -618,5 +618,6 @@ static inline bool sctp_newsk_ready(const struct sock *sk)
>  int sctp_setsockopt_bindx(struct sock *sk, struct sockaddr *kaddrs,
>  		int addrs_size, int op);
>  void sctp_sock_set_nodelay(struct sock *sk, bool val);
> +int sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim);
>  
>  #endif /* __net_sctp_h__ */
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 64c395f7a86d5..39bf8090dbe1e 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -6411,6 +6411,35 @@ static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
>  	return err;
>  }
>  
> +static int __sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim)
> +{
> +	struct sctp_association *asoc;
> +
> +	asoc = sctp_id2assoc(sk, prim->ssp_assoc_id);
> +	if (!asoc)
> +		return -EINVAL;
> +	if (!asoc->peer.primary_path)
> +		return -ENOTCONN;
> +
> +	memcpy(&prim->ssp_addr, &asoc->peer.primary_path->ipaddr,
> +		asoc->peer.primary_path->af_specific->sockaddr_len);
> +
> +	sctp_get_pf_specific(sk->sk_family)->addr_to_user(sctp_sk(sk),
> +			(union sctp_addr *)&prim->ssp_addr);
> +	return 0;
> +}
> +
> +int sctp_sock_get_primary_addr(struct sock *sk, struct sctp_prim *prim)
> +{
> +	int ret;
> +
> +	lock_sock(sk);
> +	ret = __sctp_sock_get_primary_addr(sk, prim);
> +	release_sock(sk);
> +	return ret;
> +}
> +EXPORT_SYMBOL(sctp_sock_get_primary_addr);
> +
>  /* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
>   *
>   * Requests that the local SCTP stack use the enclosed peer address as
> @@ -6421,35 +6450,19 @@ static int sctp_getsockopt_primary_addr(struct sock *sk, int len,
>  					char __user *optval, int __user *optlen)
>  {
>  	struct sctp_prim prim;
> -	struct sctp_association *asoc;
> -	struct sctp_sock *sp = sctp_sk(sk);
> +	int ret;
>  
>  	if (len < sizeof(struct sctp_prim))
>  		return -EINVAL;
> -
> -	len = sizeof(struct sctp_prim);
> -
> -	if (copy_from_user(&prim, optval, len))
> +	if (copy_from_user(&prim, optval, sizeof(struct sctp_prim)))
>  		return -EFAULT;
>  
> -	asoc = sctp_id2assoc(sk, prim.ssp_assoc_id);
> -	if (!asoc)
> -		return -EINVAL;
> -
> -	if (!asoc->peer.primary_path)
> -		return -ENOTCONN;
> -
> -	memcpy(&prim.ssp_addr, &asoc->peer.primary_path->ipaddr,
> -		asoc->peer.primary_path->af_specific->sockaddr_len);
> -
> -	sctp_get_pf_specific(sk->sk_family)->addr_to_user(sp,
> -			(union sctp_addr *)&prim.ssp_addr);
> +	ret = __sctp_sock_get_primary_addr(sk, &prim);
> +	if (ret)
> +		return ret;
>  
> -	if (put_user(len, optlen))
> +	if (put_user(len, optlen) || copy_to_user(optval, &prim, len))
>  		return -EFAULT;
> -	if (copy_to_user(optval, &prim, len))
> -		return -EFAULT;
> -
>  	return 0;
>  }
>  
> -- 
> 2.26.2
>