tls/sw: Support MSG_SPLICE_PAGES

Make TLS's sendmsg() support MSG_SPLICE_PAGES.  This causes pages to be
spliced from the source iterator if possible.

This allows ->sendpage() to be replaced by something that can handle
multiple multipage folios in a single transaction.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Boris Pismenny <borisp@nvidia.com>
cc: John Fastabend <john.fastabend@gmail.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index a2fb025..2d2bb93 100644 (file)
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -931,6 +931,35 @@ static int tls_sw_push_pending_record(struct sock *sk, int flags)
                                   &copied, flags);
 }
 
+static int tls_sw_sendmsg_splice(struct sock *sk, struct msghdr *msg,
+                                struct sk_msg *msg_pl, size_t try_to_copy,
+                                ssize_t *copied)
+{
+       struct page *page = NULL, **pages = &page;
+
+       do {
+               ssize_t part;
+               size_t off;
+
+               part = iov_iter_extract_pages(&msg->msg_iter, &pages,
+                                             try_to_copy, 1, 0, &off);
+               if (part <= 0)
+                       return part ?: -EIO;
+
+               if (WARN_ON_ONCE(!sendpage_ok(page))) {
+                       iov_iter_revert(&msg->msg_iter, part);
+                       return -EIO;
+               }
+
+               sk_msg_page_add(msg_pl, page, part, off);
+               sk_mem_charge(sk, part);
+               *copied += part;
+               try_to_copy -= part;
+       } while (try_to_copy && !sk_msg_full(msg_pl));
+
+       return 0;
+}
+
 int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 {
        long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
@@ -1020,6 +1049,17 @@ alloc_encrypted:
                        full_record = true;
                }
 
+               if (try_to_copy && (msg->msg_flags & MSG_SPLICE_PAGES)) {
+                       ret = tls_sw_sendmsg_splice(sk, msg, msg_pl,
+                                                   try_to_copy, &copied);
+                       if (ret < 0)
+                               goto send_end;
+                       tls_ctx->pending_open_record_frags = true;
+                       if (full_record || eor || sk_msg_full(msg_pl))
+                               goto copied;
+                       continue;
+               }
+
                if (!is_kvec && (full_record || eor) && !async_capable) {
                        u32 first = msg_pl->sg.end;
 
@@ -1084,6 +1124,7 @@ fallback_to_reg_send:
                 */
                tls_ctx->pending_open_record_frags = true;
                copied += try_to_copy;
+copied:
                if (full_record || eor) {
                        ret = bpf_exec_tx_verdict(msg_pl, sk, full_record,
                                                  record_type, &copied,