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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
	Brandon Cazander <brandon.cazander@multapplied.net>,
	"David S . Miller" <davem@davemloft.net>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 483/671] net: fix bpf_xdp_adjust_head regression for generic-XDP
Date: Thu, 16 Jan 2020 12:02:01 -0500
Message-ID: <20200116170509.12787-220-sashal@kernel.org> (raw)
In-Reply-To: <20200116170509.12787-1-sashal@kernel.org>

From: Jesper Dangaard Brouer <brouer@redhat.com>

[ Upstream commit 065af355470519bd184019a93ac579f22b036045 ]

When generic-XDP was moved to a later processing step by commit
458bf2f224f0 ("net: core: support XDP generic on stacked devices.")
a regression was introduced when using bpf_xdp_adjust_head.

The issue is that after this commit the skb->network_header is now
changed prior to calling generic XDP and not after. Thus, if the header
is changed by XDP (via bpf_xdp_adjust_head), then skb->network_header
also need to be updated again.  Fix by calling skb_reset_network_header().

Fixes: 458bf2f224f0 ("net: core: support XDP generic on stacked devices.")
Reported-by: Brandon Cazander <brandon.cazander@multapplied.net>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/core/dev.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 935fe158cfaf..73ebacabfde8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4349,12 +4349,17 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb,
 
 	act = bpf_prog_run_xdp(xdp_prog, xdp);
 
+	/* check if bpf_xdp_adjust_head was used */
 	off = xdp->data - orig_data;
-	if (off > 0)
-		__skb_pull(skb, off);
-	else if (off < 0)
-		__skb_push(skb, -off);
-	skb->mac_header += off;
+	if (off) {
+		if (off > 0)
+			__skb_pull(skb, off);
+		else if (off < 0)
+			__skb_push(skb, -off);
+
+		skb->mac_header += off;
+		skb_reset_network_header(skb);
+	}
 
 	/* check if bpf_xdp_adjust_tail was used. it can only "shrink"
 	 * pckt.
-- 
2.20.1


  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200116170509.12787-1-sashal@kernel.org>
2020-01-16 16:58 ` [PATCH AUTOSEL 4.19 280/671] bpf: Add missed newline in verifier verbose log Sasha Levin
2020-01-16 16:59 ` [PATCH AUTOSEL 4.19 353/671] nfp: bpf: fix static check error through tightening shift amount adjustment Sasha Levin
2020-01-16 17:00 ` [PATCH AUTOSEL 4.19 383/671] signal/bpfilter: Fix bpfilter_kernl to use send_sig not force_sig Sasha Levin
2020-01-16 17:00 ` [PATCH AUTOSEL 4.19 390/671] net: core: support XDP generic on stacked devices Sasha Levin
2020-01-16 17:00 ` [PATCH AUTOSEL 4.19 417/671] bpf: fix the check that forwarding is enabled in bpf_ipv6_fib_lookup Sasha Levin
2020-01-16 17:01 ` [PATCH AUTOSEL 4.19 437/671] tools: bpftool: use correct argument in cgroup errors Sasha Levin
2020-01-16 17:01 ` [PATCH AUTOSEL 4.19 461/671] xdp: fix possible cq entry leak Sasha Levin
2020-01-16 17:02 ` Sasha Levin [this message]
2020-01-16 17:02 ` [PATCH AUTOSEL 4.19 494/671] tools: bpftool: fix arguments for p_err() in do_event_pipe() Sasha Levin
2020-01-16 17:02 ` [PATCH AUTOSEL 4.19 495/671] tools: bpftool: fix format strings and arguments for jsonw_printf() Sasha Levin
2020-01-16 17:02 ` [PATCH AUTOSEL 4.19 529/671] xsk: avoid store-tearing when assigning queues Sasha Levin
2020-01-16 17:02 ` [PATCH AUTOSEL 4.19 530/671] xsk: avoid store-tearing when assigning umem Sasha Levin
2020-01-16 17:03 ` [PATCH AUTOSEL 4.19 558/671] bpf: fix BTF limits Sasha Levin
2020-01-16 17:04 ` [PATCH AUTOSEL 4.19 602/671] xsk: Fix registration of Rx-only sockets Sasha Levin
2020-01-16 17:04 ` [PATCH AUTOSEL 4.19 603/671] bpf, offload: Unlock on error in bpf_offload_dev_create() Sasha Levin
2020-01-16 17:05 ` [PATCH AUTOSEL 4.19 666/671] samples/bpf: Fix broken xdp_rxq_info due to map order assumptions Sasha Levin

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