[PATCH 5.4 044/155] net: ip_gre: Separate ERSPAN newlink / changelink callbacks

Greg Kroah-Hartman
2020-03-31T09:12:58Z

From: Petr Machata <petrm@mellanox.com>

[ Upstream commit e1f8f78ffe9854308b9e12a73ebe4e909074fc33 ]

ERSPAN shares most of the code path with GRE and gretap code. While that
helps keep the code compact, it is also error prone. Currently a broken
userspace can turn a gretap tunnel into a de facto ERSPAN one by passing
IFLA_GRE_ERSPAN_VER. There has been a similar issue in ip6gretap in the
past.

To prevent these problems in future, split the newlink and changelink code
paths. Split the ERSPAN code out of ipgre_netlink_parms() into a new
function erspan_netlink_parms(). Extract a piece of common logic from
ipgre_newlink() and ipgre_changelink() into ipgre_newlink_encap_setup().
Add erspan_newlink() and erspan_changelink().

Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv4/ip_gre.c | 103 ++++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 85 insertions(+), 18 deletions(-)

--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1149,6 +1149,22 @@ static int ipgre_netlink_parms(struct ne
if (data[IFLA_GRE_FWMARK])
*fwmark = nla_get_u32(data[IFLA_GRE_FWMARK]);

+ return 0;
+}
+
+static int erspan_netlink_parms(struct net_device *dev,
+ struct nlattr *data[],
+ struct nlattr *tb[],
+ struct ip_tunnel_parm *parms,
+ __u32 *fwmark)
+{
+ struct ip_tunnel *t = netdev_priv(dev);
+ int err;
+
+ err = ipgre_netlink_parms(dev, data, tb, parms, fwmark);
+ if (err)
+ return err;
+
if (data[IFLA_GRE_ERSPAN_VER]) {
t->erspan_ver = nla_get_u8(data[IFLA_GRE_ERSPAN_VER]);

@@ -1272,45 +1288,70 @@ static void ipgre_tap_setup(struct net_d
ip_tunnel_setup(dev, gre_tap_net_id);
}

-static int ipgre_newlink(struct net *src_net, struct net_device *dev,
- struct nlattr *tb[], struct nlattr *data[],
- struct netlink_ext_ack *extack)
+static int
+ipgre_newlink_encap_setup(struct net_device *dev, struct nlattr *data[])
{
- struct ip_tunnel_parm p;
struct ip_tunnel_encap ipencap;
- __u32 fwmark = 0;
- int err;

if (ipgre_netlink_encap_parms(data, &ipencap)) {
struct ip_tunnel *t = netdev_priv(dev);
- err = ip_tunnel_encap_setup(t, &ipencap);
+ int err = ip_tunnel_encap_setup(t, &ipencap);

if (err < 0)
return err;
}

+ return 0;
+}
+
+static int ipgre_newlink(struct net *src_net, struct net_device *dev,
+ struct nlattr *tb[], struct nlattr *data[],
+ struct netlink_ext_ack *extack)
+{
+ struct ip_tunnel_parm p;
+ __u32 fwmark = 0;
+ int err;
+
+ err = ipgre_newlink_encap_setup(dev, data);
+ if (err)
+ return err;
+
err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
if (err < 0)
return err;
return ip_tunnel_newlink(dev, tb, &p, fwmark);
}

+static int erspan_newlink(struct net *src_net, struct net_device *dev,
+ struct nlattr *tb[], struct nlattr *data[],
+ struct netlink_ext_ack *extack)
+{
+ struct ip_tunnel_parm p;
+ __u32 fwmark = 0;
+ int err;
+
+ err = ipgre_newlink_encap_setup(dev, data);
+ if (err)
+ return err;
+
+ err = erspan_netlink_parms(dev, data, tb, &p, &fwmark);
+ if (err)
+ return err;
+ return ip_tunnel_newlink(dev, tb, &p, fwmark);
+}
+
static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
struct ip_tunnel *t = netdev_priv(dev);
- struct ip_tunnel_encap ipencap;
__u32 fwmark = t->fwmark;
struct ip_tunnel_parm p;
int err;

- if (ipgre_netlink_encap_parms(data, &ipencap)) {
- err = ip_tunnel_encap_setup(t, &ipencap);
-
- if (err < 0)
- return err;
- }
+ err = ipgre_newlink_encap_setup(dev, data);
+ if (err)
+ return err;

err = ipgre_netlink_parms(dev, data, tb, &p, &fwmark);
if (err < 0)
@@ -1323,8 +1364,34 @@ static int ipgre_changelink(struct net_d
t->parms.i_flags = p.i_flags;
t->parms.o_flags = p.o_flags;

- if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
- ipgre_link_update(dev, !tb[IFLA_MTU]);
+ ipgre_link_update(dev, !tb[IFLA_MTU]);
+
+ return 0;
+}
+
+static int erspan_changelink(struct net_device *dev, struct nlattr *tb[],
+ struct nlattr *data[],
+ struct netlink_ext_ack *extack)
+{
+ struct ip_tunnel *t = netdev_priv(dev);
+ __u32 fwmark = t->fwmark;
+ struct ip_tunnel_parm p;
+ int err;
+
+ err = ipgre_newlink_encap_setup(dev, data);
+ if (err)
+ return err;
+
+ err = erspan_netlink_parms(dev, data, tb, &p, &fwmark);
+ if (err < 0)
+ return err;
+
+ err = ip_tunnel_changelink(dev, tb, &p, fwmark);
+ if (err < 0)
+ return err;
+
+ t->parms.i_flags = p.i_flags;
+ t->parms.o_flags = p.o_flags;

return 0;
}
@@ -1515,8 +1582,8 @@ static struct rtnl_link_ops erspan_link_
.priv_size = sizeof(struct ip_tunnel),
.setup = erspan_setup,
.validate = erspan_validate,
- .newlink = ipgre_newlink,
- .changelink = ipgre_changelink,
+ .newlink = erspan_newlink,
+ .changelink = erspan_changelink,
.dellink = ip_tunnel_dellink,
.get_size = ipgre_get_size,
.fill_info = ipgre_fill_info,