6.4-stable review patch. If anyone has any objections, please let me know.
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From: Yan Zhai yan@cloudflare.com
[ Upstream commit a171fbec88a2c730b108c7147ac5e7b2f5a02b47 ]
LWTUNNEL_XMIT_CONTINUE is implicitly assumed in ip(6)_finish_output2, such that any positive return value from a xmit hook could cause unexpected continue behavior, despite that related skb may have been freed. This could be error-prone for future xmit hook ops. One of the possible errors is to return statuses of dst_output directly.
To make the code safer, redefine LWTUNNEL_XMIT_CONTINUE value to distinguish from dst_output statuses and check the continue condition explicitly.
Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure") Suggested-by: Dan Carpenter dan.carpenter@linaro.org Signed-off-by: Yan Zhai yan@cloudflare.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Link: https://lore.kernel.org/bpf/96b939b85eda00e8df4f7c080f770970a4c5f698.1692326... Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/lwtunnel.h | 5 ++++- net/ipv4/ip_output.c | 2 +- net/ipv6/ip6_output.c | 2 +- 3 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/include/net/lwtunnel.h b/include/net/lwtunnel.h index 6f15e6fa154e6..53bd2d02a4f0d 100644 --- a/include/net/lwtunnel.h +++ b/include/net/lwtunnel.h @@ -16,9 +16,12 @@ #define LWTUNNEL_STATE_INPUT_REDIRECT BIT(1) #define LWTUNNEL_STATE_XMIT_REDIRECT BIT(2)
+/* LWTUNNEL_XMIT_CONTINUE should be distinguishable from dst_output return + * values (NET_XMIT_xxx and NETDEV_TX_xxx in linux/netdevice.h) for safety. + */ enum { LWTUNNEL_XMIT_DONE, - LWTUNNEL_XMIT_CONTINUE, + LWTUNNEL_XMIT_CONTINUE = 0x100, };
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 6f6f63cf9224f..625da48741a4f 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -216,7 +216,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s if (lwtunnel_xmit_redirect(dst->lwtstate)) { int res = lwtunnel_xmit(skb);
- if (res < 0 || res == LWTUNNEL_XMIT_DONE) + if (res != LWTUNNEL_XMIT_CONTINUE) return res; }
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 4a27fab1d09a3..50f8d2ac4e246 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -113,7 +113,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * if (lwtunnel_xmit_redirect(dst->lwtstate)) { int res = lwtunnel_xmit(skb);
- if (res < 0 || res == LWTUNNEL_XMIT_DONE) + if (res != LWTUNNEL_XMIT_CONTINUE) return res; }