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Message-Id: <20240219134821.14009-2-justin.iurman@uliege.be>
Date: Mon, 19 Feb 2024 14:48:20 +0100
From: Justin Iurman <justin.iurman@...ege.be>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
dsahern@...nel.org,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com,
linux-kernel@...r.kernel.org,
justin.iurman@...ege.be
Subject: [PATCH 1/2] Fix write to cloned skb in ipv6_hop_ioam()
ioam6_fill_trace_data() writes inside the skb payload without ensuring
it's writeable (e.g., not cloned). This function is called both from the
input and output path. The output path (ioam6_iptunnel) already does the
check. This commit provides a fix for the input path, inside
ipv6_hop_ioam(). It also updates ip6_parse_tlv() to refresh the network
header pointer ("nh") when returning from ipv6_hop_ioam().
Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace")
Reported-by: Paolo Abeni <pabeni@...hat.com>
Signed-off-by: Justin Iurman <justin.iurman@...ege.be>
---
net/ipv6/exthdrs.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 4952ae792450..02e9ffb63af1 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -177,6 +177,8 @@ static bool ip6_parse_tlv(bool hopbyhop,
case IPV6_TLV_IOAM:
if (!ipv6_hop_ioam(skb, off))
return false;
+
+ nh = skb_network_header(skb);
break;
case IPV6_TLV_JUMBO:
if (!ipv6_hop_jumbo(skb, off))
@@ -943,6 +945,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff)
if (!skb_valid_dst(skb))
ip6_route_input(skb);
+ /* About to mangle packet header */
+ if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))
+ goto drop;
+
+ /* Trace pointer may have changed */
+ trace = (struct ioam6_trace_hdr *)(skb_network_header(skb)
+ + optoff + sizeof(*hdr));
+
ioam6_fill_trace_data(skb, ns, trace, true);
break;
default:
--
2.34.1
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