[PATCH net v2] rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

[Jiayuan Chen]

On 5/8/26 2:42 PM, Hyunwoo Kim wrote:
> The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE
> handler in rxrpc_verify_response() copy the skb to a linear one before
> calling into the security ops only when skb_cloned() is true.  An skb
> that is not cloned but still carries paged fragments (skb->data_len != 0)
> falls through to the in-place decryption path, which binds the frag
> pages directly into the AEAD/skcipher SGL via skb_to_sgvec().
>
> Extend the gate so that any skb with non-linear data is also copied,
> ensuring the security handler always operates on a fully linear skb.
> The OOM/trace handling already in place is reused.
>
> Fixes: d0d5c0cd1e71 ("rxrpc: Use skb_unshare() rather than skb_cow_data()")
> Cc: stable at vger.kernel.org
> Signed-off-by: Hyunwoo Kim <imv4bel at gmail.com>
> ---
> Changes in v2:
> - Use skb_is_nonlinear() instead of skb->data_len
> - v1: https://lore.kernel.org/all/afKV2zGR6rrelPC7@v4bel/
> ---
>   net/rxrpc/call_event.c | 2 +-
>   net/rxrpc/conn_event.c | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
> index fdd683261226..a6ad5ff6ec5f 100644
> --- a/net/rxrpc/call_event.c
> +++ b/net/rxrpc/call_event.c
> @@ -334,7 +334,7 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
>   
>   			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
>   			    sp->hdr.securityIndex != 0 &&
> -			    skb_cloned(skb)) {
> +			    (skb_cloned(skb) || skb_is_nonlinear(skb))) {
>   				/* Unshare the packet so that it can be
>   				 * modified by in-place decryption.
>   				 */
> diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
> index a2130d25aaa9..632cbeff1f5d 100644
> --- a/net/rxrpc/conn_event.c
> +++ b/net/rxrpc/conn_event.c
> @@ -245,7 +245,7 @@ static int rxrpc_verify_response(struct rxrpc_connection *conn,
>   {
>   	int ret;
>   
> -	if (skb_cloned(skb)) {
> +	if (skb_cloned(skb) || skb_is_nonlinear(skb)) {
>   		/* Copy the packet if shared so that we can do in-place
>   		 * decryption.
>   		 */


Why not adopt the same gate as the ESP fix:


     skb_cloned(skb) || skb_has_frag_list(skb) || skb_has_shared_frag(skb)


so NIC page_pool RX keeps its zero-copy path while still catching the 
splice-loopback vector?