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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 08/55] tcp: Make sendmsg(MSG_SPLICE_PAGES) copy unspliceable data Date: Fri, 31 Mar 2023 17:08:27 +0100 Message-Id: <20230331160914.1608208-9-dhowells@redhat.com> In-Reply-To: <20230331160914.1608208-1-dhowells@redhat.com> References: <20230331160914.1608208-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D944780026 X-Stat-Signature: pr8999gyu1bctmiengdq44ugp5nc47kh X-Rspam-User: X-HE-Tag: 1680278990-809573 X-HE-Meta: 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 3fKE27Nk We3aiGx692jaSWPt4LSN5hA1SWnFPKvdz5LCC2kLSGnoqJM7CMXNSLxFasx1Sgl4j7e8bJpWhQKYH+wS/bzJFyXLG/sWEeEU5jJEXGbEaK03sxxyx4AHl7w2slW63UqPv2XtRBqBPD9hFvFaBLeSYeDfIRVILyweWbG3q5etMPwODJXlORt8WGRJtb3e2C7qzxSmACjO1YwJNCikNzd2Y6hVs1UX0ps5E4u5qlKaOUvz8OJ22Zwy+ToJ9U6aMvHlQOWdOYBMRqKh21banarzlP7ponft9CO1gU6GFI1NmKusmJSgtGXjVF1/gragaKICrjsM1l9Ot0mQ2M3kdhT410jjTITTxT1hNV69GYwQ9DLS5zAPawbmO0uc2URo3yq0rCppySihOMRs+tUNPV6x6XKMmzwaxOIFqojUeud+yRzaStRe0U5LPadCBxhrrt5InQjFi X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 tcp_sendmsg() copy it. Signed-off-by: David Howells cc: Eric Dumazet cc: "David S. Miller" cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/ipv4/tcp.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 910b327c236e..6ef0518eb706 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1417,10 +1417,10 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) goto do_error; copy = err; } else if (zc == 2) { - /* Splice in data. */ + /* Splice in data if we can; copy if we can't. */ struct page *page = NULL, **pages = &page; size_t off = 0, part; - bool can_coalesce; + bool can_coalesce, put = false; int i = skb_shinfo(skb)->nr_frags; copy = iov_iter_extract_pages(&msg->msg_iter, &pages, @@ -1447,12 +1447,34 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) goto wait_for_space; copy = part; + 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) { + iov_iter_revert(&msg->msg_iter, copy); + err = copy ?: -ENOMEM; + goto do_error; + } + page = virt_to_page(q); + off = offset_in_page(q); + put = true; + can_coalesce = false; + } + if (can_coalesce) { skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy); } else { - get_page(page); + if (!put) + get_page(page); + put = false; skb_fill_page_desc_noacc(skb, i, page, off, copy); } + if (put) + put_page(page); page = NULL; if (!(flags & MSG_NO_SHARED_FRAGS))