[RFC PATCH v2 17/48] ip, udp: Make sendmsg(MSG_SPLICE_PAGES) copy unspliceable data
From: David Howells <dhowells@redhat.com>
Date: 2023-03-29 14:18:03
Also in:
linux-fsdevel, linux-mm, lkml
Subsystem:
networking [general], networking [ipv4/ipv6], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds
If sendmsg() with MSG_SPLICE_PAGES encounters a page that shouldn't be spliced - a slab page, for instance, or one with a zero count - make __ip_append_data() copy it. Signed-off-by: David Howells <dhowells@redhat.com> cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com> cc: "David S. Miller" <davem@davemloft.net> cc: Eric Dumazet <edumazet@google.com> cc: Jakub Kicinski <kuba@kernel.org> cc: Paolo Abeni <pabeni@redhat.com> cc: Jens Axboe <axboe@kernel.dk> cc: Matthew Wilcox <willy@infradead.org> cc: netdev@vger.kernel.org --- net/ipv4/ip_output.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 07736da70eab..e4aeaab704c8 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c@@ -1263,6 +1263,7 @@ static int __ip_append_data(struct sock *sk, struct msghdr *msg = from; struct page *page = NULL, **pages = &page; size_t off; + bool put = false; copy = iov_iter_extract_pages(&msg->msg_iter, &pages, copy, 1, 0, &off);
@@ -1271,7 +1272,25 @@ static int __ip_append_data(struct sock *sk, goto error; } + if (!sendpage_ok(page)) { + const void *p = kmap_local_page(page); + void *q; + + q = page_frag_memdup(NULL, p + off, copy, + sk->sk_allocation, ULONG_MAX); + kunmap_local(p); + if (!q) { + err = copy ?: -ENOMEM; + goto error; + } + page = virt_to_page(q); + off = offset_in_page(q); + put = true; + } + err = skb_append_pagefrags(skb, page, off, copy); + if (put) + put_page(page); if (err < 0) goto error;