[PATCH net-next v6 12/14] tls/sw: Convert tls_sw_sendpage() to use MSG_SPLICE_PAGES

David Howells
2023-06-07T18:22:12Z

Convert tls_sw_sendpage() and tls_sw_sendpage_locked() to use sendmsg()
with MSG_SPLICE_PAGES rather than directly splicing in the pages itself.

[!] Note that tls_sw_sendpage_locked() appears to have the wrong locking
upstream. I think the caller will only hold the socket lock, but it
should hold tls_ctx->tx_lock too.

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>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Boris Pismenny <borisp@nvidia.com>
cc: John Fastabend <john.fastabend@gmail.com>
cc: Eric Dumazet <edumazet@google.com>
cc: "David S. Miller" <davem@davemloft.net>
cc: Paolo Abeni <pabeni@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: netdev@vger.kernel.org
cc: bpf@vger.kernel.org
---
net/tls/tls_sw.c | 173 ++++++++++-------------------------------------
1 file changed, 35 insertions(+), 138 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 2d2bb933d2a6..319f61590d2c 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -960,7 +960,8 @@ static int tls_sw_sendmsg_splice(struct sock *sk, struct msghdr *msg,
return 0;
}

-int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
+static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg,
+ size_t size)
{
long timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
struct tls_context *tls_ctx = tls_get_ctx(sk);
@@ -983,15 +984,6 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
int ret = 0;
int pending;

- if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
- MSG_CMSG_COMPAT | MSG_SPLICE_PAGES))
- return -EOPNOTSUPP;
-
- ret = mutex_lock_interruptible(&tls_ctx->tx_lock);
- if (ret)
- return ret;
- lock_sock(sk);
-
if (unlikely(msg->msg_controllen)) {
ret = tls_process_cmsg(sk, msg, &record_type);
if (ret) {
@@ -1192,10 +1184,27 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)

send_end:
ret = sk_stream_error(sk, msg->msg_flags, ret);
+ return copied > 0 ? copied : ret;
+}

+int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
+{
+ struct tls_context *tls_ctx = tls_get_ctx(sk);
+ int ret;
+
+ if (msg->msg_flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
+ MSG_CMSG_COMPAT | MSG_SPLICE_PAGES |
+ MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY))
+ return -EOPNOTSUPP;
+
+ ret = mutex_lock_interruptible(&tls_ctx->tx_lock);
+ if (ret)
+ return ret;
+ lock_sock(sk);
+ ret = tls_sw_sendmsg_locked(sk, msg, size);
release_sock(sk);
mutex_unlock(&tls_ctx->tx_lock);
- return copied > 0 ? copied : ret;
+ return ret;
}

/*
@@ -1272,151 +1281,39 @@ void tls_sw_splice_eof(struct socket *sock)
mutex_unlock(&tls_ctx->tx_lock);
}

-static int tls_sw_do_sendpage(struct sock *sk, struct page *page,
- int offset, size_t size, int flags)
-{
- long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
- struct tls_context *tls_ctx = tls_get_ctx(sk);
- struct tls_sw_context_tx *ctx = tls_sw_ctx_tx(tls_ctx);
- struct tls_prot_info *prot = &tls_ctx->prot_info;
- unsigned char record_type = TLS_RECORD_TYPE_DATA;
- struct sk_msg *msg_pl;
- struct tls_rec *rec;
- int num_async = 0;
- ssize_t copied = 0;
- bool full_record;
- int record_room;
- int ret = 0;
- bool eor;
-
- eor = !(flags & MSG_SENDPAGE_NOTLAST);
- sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
-
- /* Call the sk_stream functions to manage the sndbuf mem. */
- while (size > 0) {
- size_t copy, required_size;
-
- if (sk->sk_err) {
- ret = -sk->sk_err;
- goto sendpage_end;
- }
-
- if (ctx->open_rec)
- rec = ctx->open_rec;
- else
- rec = ctx->open_rec = tls_get_rec(sk);
- if (!rec) {
- ret = -ENOMEM;
- goto sendpage_end;
- }
-
- msg_pl = &rec->msg_plaintext;
-
- full_record = false;
- record_room = TLS_MAX_PAYLOAD_SIZE - msg_pl->sg.size;
- copy = size;
- if (copy >= record_room) {
- copy = record_room;
- full_record = true;
- }
-
- required_size = msg_pl->sg.size + copy + prot->overhead_size;
-
- if (!sk_stream_memory_free(sk))
- goto wait_for_sndbuf;
-alloc_payload:
- ret = tls_alloc_encrypted_msg(sk, required_size);
- if (ret) {
- if (ret != -ENOSPC)
- goto wait_for_memory;
-
- /* Adjust copy according to the amount that was
- * actually allocated. The difference is due
- * to max sg elements limit
- */
- copy -= required_size - msg_pl->sg.size;
- full_record = true;
- }
-
- sk_msg_page_add(msg_pl, page, copy, offset);
- sk_mem_charge(sk, copy);
-
- offset += copy;
- size -= copy;
- copied += copy;
-
- tls_ctx->pending_open_record_frags = true;
- if (full_record || eor || sk_msg_full(msg_pl)) {
- ret = bpf_exec_tx_verdict(msg_pl, sk, full_record,
- record_type, &copied, flags);
- if (ret) {
- if (ret == -EINPROGRESS)
- num_async++;
- else if (ret == -ENOMEM)
- goto wait_for_memory;
- else if (ret != -EAGAIN) {
- if (ret == -ENOSPC)
- ret = 0;
- goto sendpage_end;
- }
- }
- }
- continue;
-wait_for_sndbuf:
- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
-wait_for_memory:
- ret = sk_stream_wait_memory(sk, &timeo);
- if (ret) {
- if (ctx->open_rec)
- tls_trim_both_msgs(sk, msg_pl->sg.size);
- goto sendpage_end;
- }
-
- if (ctx->open_rec)
- goto alloc_payload;
- }
-
- if (num_async) {
- /* Transmit if any encryptions have completed */
- if (test_and_clear_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask)) {
- cancel_delayed_work(&ctx->tx_work.work);
- tls_tx_records(sk, flags);
- }
- }
-sendpage_end:
- ret = sk_stream_error(sk, flags, ret);
- return copied > 0 ? copied : ret;
-}
-
int tls_sw_sendpage_locked(struct sock *sk, struct page *page,
int offset, size_t size, int flags)
{
+ struct bio_vec bvec;
+ struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES, };
+
if (flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY |
MSG_NO_SHARED_FRAGS))
return -EOPNOTSUPP;
+ if (flags & MSG_SENDPAGE_NOTLAST)
+ msg.msg_flags |= MSG_MORE;

- return tls_sw_do_sendpage(sk, page, offset, size, flags);
+ bvec_set_page(&bvec, page, size, offset);
+ iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
+ return tls_sw_sendmsg_locked(sk, &msg, size);
}

int tls_sw_sendpage(struct sock *sk, struct page *page,
int offset, size_t size, int flags)
{
- struct tls_context *tls_ctx = tls_get_ctx(sk);
- int ret;
+ struct bio_vec bvec;
+ struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES, };

if (flags & ~(MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL |
MSG_SENDPAGE_NOTLAST | MSG_SENDPAGE_NOPOLICY))
return -EOPNOTSUPP;
+ if (flags & MSG_SENDPAGE_NOTLAST)
+ msg.msg_flags |= MSG_MORE;

- ret = mutex_lock_interruptible(&tls_ctx->tx_lock);
- if (ret)
- return ret;
- lock_sock(sk);
- ret = tls_sw_do_sendpage(sk, page, offset, size, flags);
- release_sock(sk);
- mutex_unlock(&tls_ctx->tx_lock);
- return ret;
+ bvec_set_page(&bvec, page, size, offset);
+ iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
+ return tls_sw_sendmsg(sk, &msg, size);
}

static int