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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: [RFC PATCH v2 20/48] af_unix: Make sendmsg(MSG_SPLICE_PAGES) copy unspliceable data Date: Wed, 29 Mar 2023 15:13:26 +0100 Message-Id: <20230329141354.516864-21-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9D337120030 X-Stat-Signature: hdfb1oikfp5ufj9pk16g7jf8b1ezzthk X-HE-Tag: 1680099301-977577 X-HE-Meta: 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 z71I5/Gh J2Ot+VXRf5JrA8QedfHIHyiAA6oFRJU0AwU+XNgwgYIGAqpDGkTbULQqRs9ue0UC1vCaAyBrag23tIAueiV0MhIU378jkUHCNOK8lKpzhFRn1zavtW7VGFqOI7ydsbFf/UJx1cqEfc6Md0+VFtMTeE0yYM1NbUzLPXHcSWs0ShF7DTdHzItYzRSMPZ7+eHrWoOkdXJWjiuhHPzOKJg3p2W+jUESztExQkRE5lRBD/vFDyfLtGMe7dwvmx9OOxS56uygDlXLTmPqCprAg8xaVneeliatq33MzCXUZOqCNKEo/LrPYdCdOgFR0bidXdHFHtrdbWHG70++K5rszt63RymDru+EQUx0lXf4OEh0dAR+9blbxlo8F42E5b1JRcKc31cqrhIXQMyV6PomD7sBx22BHICpJ97At4soLb64zLI42OVuHnmXqI/ewirPpvhn72pFcOaQJWOdMQmEhd5TWb1PB82AgyS/Oia8ulrXO8yXEBirY= 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 unix_extract_bvec_to_skb() copy it. Signed-off-by: David Howells cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/unix/af_unix.c | 44 +++++++++++++++++++++++++++++++++----------- 1 file changed, 33 insertions(+), 11 deletions(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 84a0d97f1aa4..b4b27a652ef0 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -2154,12 +2154,12 @@ static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other /* * Extract pages from an iterator and add them to the socket buffer. */ -static ssize_t unix_extract_bvec_to_skb(struct sk_buff *skb, - struct iov_iter *iter, ssize_t maxsize) +static ssize_t unix_extract_bvec_to_skb(struct sk_buff *skb, struct iov_iter *iter, + ssize_t maxsize, gfp_t gfp) { struct page *pages[8], **ppages = pages; unsigned int i, nr; - ssize_t ret = 0; + ssize_t spliced = 0, ret = 0; while (iter->count > 0) { size_t off, len; @@ -2171,31 +2171,52 @@ static ssize_t unix_extract_bvec_to_skb(struct sk_buff *skb, len = iov_iter_extract_pages(iter, &ppages, maxsize, nr, 0, &off); if (len <= 0) { - if (!ret) - ret = len ?: -EIO; + ret = len ?: -EIO; break; } i = 0; do { + struct page *page = pages[i++]; size_t part = min(PAGE_SIZE - off, len); + bool put = false; + + if (!sendpage_ok(page)) { + const void *p = kmap_local_page(page); + void *q; + + q = page_frag_memdup(NULL, p + off, part, gfp, + ULONG_MAX); + kunmap_local(p); + if (!q) { + iov_iter_revert(iter, len); + ret = -ENOMEM; + goto out; + } + page = virt_to_page(q); + off = offset_in_page(q); + put = true; + } - if (skb_append_pagefrags(skb, pages[i++], off, part) < 0) { - if (!ret) - ret = -EMSGSIZE; + ret = skb_append_pagefrags(skb, page, off, part); + if (put) + put_page(page); + if (ret < 0) { + iov_iter_revert(iter, len); goto out; } off = 0; - ret += part; + spliced += part; maxsize -= part; len -= part; } while (len > 0); + if (maxsize <= 0) break; } out: - return ret; + return spliced ?: ret; } static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, @@ -2272,7 +2293,8 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg, fds_sent = true; if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) { - size = unix_extract_bvec_to_skb(skb, &msg->msg_iter, size); + size = unix_extract_bvec_to_skb(skb, &msg->msg_iter, size, + sk->sk_allocation); skb->data_len += size; skb->len += size; skb->truesize += size;