[RFC PATCH v3 02/20] tcp: don't allow non-devmem originated ppiov

[David Wei <dw@davidwei.uk>]

From: Pavel Begunkov <asml.silence@gmail.com>

NOT FOR UPSTREAM

There will be more users of struct page_pool_iov, and ppiovs from one
subsystem must not be used by another. That should never happen for any
sane application, but we need to enforce it in case of bufs and/or
malicious users.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: David Wei <dw@davidwei.uk>
---
 net/ipv4/tcp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 33a8bb63fbf5..9c6b18eebb5b 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2384,6 +2384,13 @@ static int tcp_recvmsg_devmem(const struct sock *sk, const struct sk_buff *skb,
 			}
 
 			ppiov = skb_frag_page_pool_iov(frag);
+
+			/* Disallow non devmem owned buffers */
+			if (ppiov->pp->p.memory_provider != PP_MP_DMABUF_DEVMEM) {
+				err = -ENODEV;
+				goto out;
+			}
+
 			end = start + skb_frag_size(frag);
 			copy = end - offset;
 
-- 
2.39.3