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net: ip_gre: Separate ERSPAN newlink / changelink callbacks 

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: 84e54fe0a5 ("gre: introduce native tunnel support for ERSPAN")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Petr Machata 2020-03-13 13:39:36 +02:00 committed by David S. Miller
parent 46ea929b2b
commit e1f8f78ffe
1 changed files with 85 additions and 18 deletions
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103
net/ipv4/ip_gre.c
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@ -1153,6 +1153,22 @@ static int ipgre_netlink_parms(struct net_device *dev,
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]);
@ -1276,45 +1292,70 @@ static void ipgre_tap_setup(struct net_device *dev)
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)
@ -1327,8 +1368,34 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
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;
}
@ -1519,8 +1586,8 @@ static struct rtnl_link_ops erspan_link_ops __read_mostly = {
.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,