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Message-ID: <dca049d75d60d740d0736bfecfa4616be1d2388a.1731941465.git.petrm@nvidia.com>
Date: Mon, 18 Nov 2024 17:43:11 +0100
From: Petr Machata <petrm@...dia.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
<pabeni@...hat.com>, <netdev@...r.kernel.org>
CC: Simon Horman <horms@...nel.org>, Ido Schimmel <idosch@...dia.com>, "Petr
Machata" <petrm@...dia.com>, <mlxsw@...dia.com>, Andrew Lunn
<andrew+netdev@...n.ch>, Menglong Dong <menglong8.dong@...il.com>, "Guillaume
Nault" <gnault@...hat.com>, Alexander Lobakin <aleksander.lobakin@...el.com>,
Breno Leitao <leitao@...ian.org>
Subject: [RFC PATCH net-next 05/11] vxlan: Track reserved bits explicitly as part of the configuration
In order to make it possible to configure which bits in VXLAN header should
be considered reserved, introduce afield new vxlan_config::reserved_bits.
Have it cover the whole header, except for the VNI-present bit and the bits
for VNI itself, and have individual enabled features clear more bits off
reserved_bits.
(This is expressed as first constructing a used_bits set, and then
inverting it to get the reserved_bits. The set of used_bits will be useful
on its own for validation of user-set reserved_bits in a following patch.)
The patch also moves a comment relevant to the validation from the unparsed
validation site up to the new site. Logically this patch should add the new
comment, and a later patch that removes the unparsed bits would remove the
old comment. But keeping both legs in the same patch is better from the
history spelunking point of view.
Signed-off-by: Petr Machata <petrm@...dia.com>
Reviewed-by: Ido Schimmel <idosch@...dia.com>
---
Notes:
CC: Andrew Lunn <andrew+netdev@...n.ch>
CC: Menglong Dong <menglong8.dong@...il.com>
CC: Guillaume Nault <gnault@...hat.com>
CC: Alexander Lobakin <aleksander.lobakin@...el.com>
CC: Breno Leitao <leitao@...ian.org>
drivers/net/vxlan/vxlan_core.c | 41 +++++++++++++++++++++++++---------
include/net/vxlan.h | 1 +
2 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index 95d6b438cb7a..d3d5dfab5f5b 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -1710,9 +1710,20 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
goto drop;
}
- /* For backwards compatibility, only allow reserved fields to be
- * used by VXLAN extensions if explicitly requested.
- */
+ if (vh->vx_flags & vxlan->cfg.reserved_bits.vx_flags ||
+ vh->vx_vni & vxlan->cfg.reserved_bits.vx_vni) {
+ /* If the header uses bits besides those enabled by the
+ * netdevice configuration, treat this as a malformed packet.
+ * This behavior diverges from VXLAN RFC (RFC7348) which
+ * stipulates that bits in reserved in reserved fields are to be
+ * ignored. The approach here maintains compatibility with
+ * previous stack code, and also is more robust and provides a
+ * little more security in adding extensions to VXLAN.
+ */
+ reason = SKB_DROP_REASON_VXLAN_INVALID_HDR;
+ goto drop;
+ }
+
if (vxlan->cfg.flags & VXLAN_F_GPE) {
if (!vxlan_parse_gpe_proto(vh, &protocol))
goto drop;
@@ -1763,14 +1774,6 @@ static int vxlan_rcv(struct sock *sk, struct sk_buff *skb)
*/
if (unparsed.vx_flags || unparsed.vx_vni) {
- /* If there are any unprocessed flags remaining treat
- * this as a malformed packet. This behavior diverges from
- * VXLAN RFC (RFC7348) which stipulates that bits in reserved
- * in reserved fields are to be ignored. The approach here
- * maintains compatibility with previous stack code, and also
- * is more robust and provides a little more security in
- * adding extensions to VXLAN.
- */
reason = SKB_DROP_REASON_VXLAN_INVALID_HDR;
goto drop;
}
@@ -4070,6 +4073,10 @@ static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
struct net_device *dev, struct vxlan_config *conf,
bool changelink, struct netlink_ext_ack *extack)
{
+ struct vxlanhdr used_bits = {
+ .vx_flags = VXLAN_HF_VNI,
+ .vx_vni = VXLAN_VNI_MASK,
+ };
struct vxlan_dev *vxlan = netdev_priv(dev);
int err = 0;
@@ -4296,6 +4303,8 @@ static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
extack);
if (err)
return err;
+ used_bits.vx_flags |= VXLAN_HF_RCO;
+ used_bits.vx_vni |= ~VXLAN_VNI_MASK;
}
if (data[IFLA_VXLAN_GBP]) {
@@ -4303,6 +4312,7 @@ static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
VXLAN_F_GBP, changelink, false, extack);
if (err)
return err;
+ used_bits.vx_flags |= VXLAN_GBP_USED_BITS;
}
if (data[IFLA_VXLAN_GPE]) {
@@ -4311,8 +4321,17 @@ static int vxlan_nl2conf(struct nlattr *tb[], struct nlattr *data[],
extack);
if (err)
return err;
+
+ used_bits.vx_flags |= VXLAN_GPE_USED_BITS;
}
+ /* For backwards compatibility, only allow reserved fields to be
+ * used by VXLAN extensions if explicitly requested.
+ */
+ conf->reserved_bits = (struct vxlanhdr) {
+ .vx_flags = ~used_bits.vx_flags,
+ .vx_vni = ~used_bits.vx_vni,
+ };
if (data[IFLA_VXLAN_REMCSUM_NOPARTIAL]) {
err = vxlan_nl2flag(conf, data, IFLA_VXLAN_REMCSUM_NOPARTIAL,
VXLAN_F_REMCSUM_NOPARTIAL, changelink,
diff --git a/include/net/vxlan.h b/include/net/vxlan.h
index 33ba6fc151cf..2dd23ee2bacd 100644
--- a/include/net/vxlan.h
+++ b/include/net/vxlan.h
@@ -227,6 +227,7 @@ struct vxlan_config {
unsigned int addrmax;
bool no_share;
enum ifla_vxlan_df df;
+ struct vxlanhdr reserved_bits;
};
enum {
--
2.47.0
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