2018-09-14 04:27:32

by Haishuang Yan

Subject: [PATCH v3,net-next 1/2] ip_gre: fix parsing gre header in ipgre_err

gre_parse_header stops parsing when csum_err is encountered, which means
tpi->key is undefined and ip_tunnel_lookup will return NULL improperly.

This patch introduce a NULL pointer as csum_err parameter. Even when
csum_err is encountered, it won't return error and continue parsing gre
header as expected.

Fixes: 9f57c67c379d ("gre: Remove support for sharing GRE protocol hook.")
Reported-by: Jiri Benc <[email protected]>
Signed-off-by: Haishuang Yan <[email protected]>

---
Changes since v3:
* skb_checksum_simple_validate need to be performed in csum_err case.
---
net/ipv4/gre_demux.c | 7 ++++---
net/ipv4/ip_gre.c | 9 +++------
2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index b798862..7efe740 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -86,13 +86,14 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,

options = (__be32 *)(greh + 1);
if (greh->flags & GRE_CSUM) {
- if (skb_checksum_simple_validate(skb)) {
+ if (!skb_checksum_simple_validate(skb)) {
+ skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
+ null_compute_pseudo);
+ } else if (csum_err) {
*csum_err = true;
return -EINVAL;
}

- skb_checksum_try_convert(skb, IPPROTO_GRE, 0,
- null_compute_pseudo);
options++;
}

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 8cce0e9..c3385a8 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -232,13 +232,10 @@ static void gre_err(struct sk_buff *skb, u32 info)
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
struct tnl_ptk_info tpi;
- bool csum_err = false;

- if (gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP),
- iph->ihl * 4) < 0) {
- if (!csum_err) /* ignore csum errors. */
- return;
- }
+ if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP),
+ iph->ihl * 4) < 0)
+ return;

if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
ipv4_update_pmtu(skb, dev_net(skb->dev), info,
--
1.8.3.1

2018-09-14 04:28:48

by Haishuang Yan

Subject: [PATCH v3,net-next 2/2] ip6_gre: simplify gre header parsing in ip6gre_err

Same as ip_gre, use gre_parse_header to parse gre header in gre error
handler code.

Signed-off-by: Haishuang Yan <[email protected]>
---
net/ipv6/ip6_gre.c | 26 ++++----------------------
1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index e493b04..515adbd 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -427,35 +427,17 @@ static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
u8 type, u8 code, int offset, __be32 info)
{
struct net *net = dev_net(skb->dev);
- const struct gre_base_hdr *greh;
const struct ipv6hdr *ipv6h;
- int grehlen = sizeof(*greh);
+ struct tnl_ptk_info tpi;
struct ip6_tnl *t;
- int key_off = 0;
- __be16 flags;
- __be32 key;

- if (!pskb_may_pull(skb, offset + grehlen))
- return;
- greh = (const struct gre_base_hdr *)(skb->data + offset);
- flags = greh->flags;
- if (flags & (GRE_VERSION | GRE_ROUTING))
+ if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IPV6),
+ offset) < 0)
return;
- if (flags & GRE_CSUM)
- grehlen += 4;
- if (flags & GRE_KEY) {
- key_off = grehlen + offset;
- grehlen += 4;
- }

- if (!pskb_may_pull(skb, offset + grehlen))
- return;
ipv6h = (const struct ipv6hdr *)skb->data;
- greh = (const struct gre_base_hdr *)(skb->data + offset);
- key = key_off ? *(__be32 *)(skb->data + key_off) : 0;
-
t = ip6gre_tunnel_lookup(skb->dev, &ipv6h->daddr, &ipv6h->saddr,
- key, greh->protocol);
+ tpi.key, tpi.proto);
if (!t)
return;

--
1.8.3.1

2018-09-16 22:34:54

by David Miller

Subject: Re: [PATCH v3,net-next 1/2] ip_gre: fix parsing gre header in ipgre_err

From: Haishuang Yan <[email protected]>
Date: Fri, 14 Sep 2018 12:26:47 +0800

> gre_parse_header stops parsing when csum_err is encountered, which means
> tpi->key is undefined and ip_tunnel_lookup will return NULL improperly.
>
> This patch introduce a NULL pointer as csum_err parameter. Even when
> csum_err is encountered, it won't return error and continue parsing gre
> header as expected.
>
> Fixes: 9f57c67c379d ("gre: Remove support for sharing GRE protocol hook.")
> Reported-by: Jiri Benc <[email protected]>
> Signed-off-by: Haishuang Yan <[email protected]>
>
> ---
> Changes since v3:
> * skb_checksum_simple_validate need to be performed in csum_err case.

Applied.

2018-09-16 22:36:38

by David Miller

Subject: Re: [PATCH v3,net-next 2/2] ip6_gre: simplify gre header parsing in ip6gre_err

From: Haishuang Yan <[email protected]>
Date: Fri, 14 Sep 2018 12:26:48 +0800

> Same as ip_gre, use gre_parse_header to parse gre header in gre error
> handler code.
>
> Signed-off-by: Haishuang Yan <[email protected]>

Applied.