Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier
On 2/4/18 5:11 AM, Christian Brauner wrote:
> On Sat, Feb 03, 2018 at 11:17:01AM -0800, Stephen Hemminger wrote:
>> On Sat, 3 Feb 2018 14:29:04 +0100
>> Christian Brauner wrote:
>>
>>> +static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
>>> +struct nlattr *tb[],
>>> +struct netlink_ext_ack *extack)
>>> +{
>>> + int ret = -EINVAL;
>>> + struct net *net = NULL, *unique_net = NULL;
>>> +
>>> + /* Requests without network namespace ids have been able to specify
>>> +* multiple properties referring to different network namespaces so
>>> +* don't regress them.
>>> +*/
>>> + if (!tb[IFLA_IF_NETNSID])
>>> + return 0;
>>> +
>>> + if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
>>> + return 0;
>>
>> Isn't this an error?
>
> My reasoning was that having no explicit network namespace identifying
> attributes the caller operates on the current network namespace which is
> uniquely identified.
agreed. those are not required attributes.
Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier
On Sat, Feb 03, 2018 at 07:09:55PM -0700, David Ahern wrote:
> On 2/3/18 12:17 PM, Stephen Hemminger wrote:
> > On Sat, 3 Feb 2018 14:29:04 +0100
> > Christian Brauner wrote:
> >
> >> +static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
> >> + struct nlattr *tb[],
> >> + struct netlink_ext_ack *extack)
> >> +{
> >> + int ret = -EINVAL;
> >> + struct net *net = NULL, *unique_net = NULL;
> >> +
> >> + /* Requests without network namespace ids have been able to specify
> >> + * multiple properties referring to different network namespaces so
> >> + * don't regress them.
> >> + */
> >> + if (!tb[IFLA_IF_NETNSID])
> >> + return 0;
> >> +
> >> + if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
> >> + return 0;
> >
> > Isn't this an error?
> >
> >> +
> >> + unique_net = get_net_ns_by_id(sock_net(sk),
> >> nla_get_s32(tb[IFLA_IF_NETNSID]));
> >> + if (!unique_net)
> >> + return -1;
> >
> > Other paths are returning errno, so why -1 here?
> >
>
> extack needs to be filled in too.
Yeah, it should report that an invalid network namespace identifier has
been specified.
Thanks!
Christian
Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier
On Sat, Feb 03, 2018 at 11:17:01AM -0800, Stephen Hemminger wrote:
> On Sat, 3 Feb 2018 14:29:04 +0100
> Christian Brauner wrote:
>
> > +static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
> > +struct nlattr *tb[],
> > +struct netlink_ext_ack *extack)
> > +{
> > + int ret = -EINVAL;
> > + struct net *net = NULL, *unique_net = NULL;
> > +
> > + /* Requests without network namespace ids have been able to specify
> > +* multiple properties referring to different network namespaces so
> > +* don't regress them.
> > +*/
> > + if (!tb[IFLA_IF_NETNSID])
> > + return 0;
> > +
> > + if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
> > + return 0;
>
> Isn't this an error?
My reasoning was that having no explicit network namespace identifying
attributes the caller operates on the current network namespace which is
uniquely identified.
>
> > +
> > + unique_net = get_net_ns_by_id(sock_net(sk),
> > nla_get_s32(tb[IFLA_IF_NETNSID]));
> > + if (!unique_net)
> > + return -1;
>
> Other paths are returning errno, so why -1 here?
Yes, this should be -EINVAL as well.
Thanks!
Christian
Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier
On 2/3/18 12:17 PM, Stephen Hemminger wrote:
> On Sat, 3 Feb 2018 14:29:04 +0100
> Christian Brauner wrote:
>
>> +static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
>> + struct nlattr *tb[],
>> + struct netlink_ext_ack *extack)
>> +{
>> +int ret = -EINVAL;
>> +struct net *net = NULL, *unique_net = NULL;
>> +
>> +/* Requests without network namespace ids have been able to specify
>> + * multiple properties referring to different network namespaces so
>> + * don't regress them.
>> + */
>> +if (!tb[IFLA_IF_NETNSID])
>> +return 0;
>> +
>> +if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
>> +return 0;
>
> Isn't this an error?
>
>> +
>> +unique_net = get_net_ns_by_id(sock_net(sk),
>> nla_get_s32(tb[IFLA_IF_NETNSID]));
>> +if (!unique_net)
>> +return -1;
>
> Other paths are returning errno, so why -1 here?
>
extack needs to be filled in too.
Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier
On Sat, 3 Feb 2018 14:29:04 +0100
Christian Brauner wrote:
> +static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
> + struct nlattr *tb[],
> + struct netlink_ext_ack *extack)
> +{
> + int ret = -EINVAL;
> + struct net *net = NULL, *unique_net = NULL;
> +
> + /* Requests without network namespace ids have been able to specify
> + * multiple properties referring to different network namespaces so
> + * don't regress them.
> + */
> + if (!tb[IFLA_IF_NETNSID])
> + return 0;
> +
> + if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
> + return 0;
Isn't this an error?
> +
> + unique_net = get_net_ns_by_id(sock_net(sk),
> nla_get_s32(tb[IFLA_IF_NETNSID]));
> + if (!unique_net)
> + return -1;
Other paths are returning errno, so why -1 here?
[PATCH net 1/1 v1] rtnetlink: require unique netns identifier
Since we've added support for IFLA_IF_NETNSID for RTM_{DEL,GET,SET,NEW}LINK
it is possible for userspace to send us requests with three different
properties to identify a target network namespace. This affects at least
RTM_{NEW,SET}LINK. Each of them could potentially refer to a different
network namespace which is confusing. For legacy reasons the kernel will
pick the IFLA_NET_NS_PID property first and then look for the
IFLA_NET_NS_FD property but there is no reason to extend this type of
behavior to network namespace ids. The regression potential is quite
minimal since the rtnetlink requests in question either won't allow
IFLA_IF_NETNSID requests before 4.16 is out (RTM_{NEW,SET}LINK) or don't
support IFLA_NET_NS_{PID,FD} (RTM_{DEL,GET}LINK) in the first place.
Signed-off-by: Christian Brauner
---
ChangeLog v0->v1:
* report a descriptive error to userspace via struct netlink_ext_ack
* do not fail when multiple properties specifiy the same network namespace
---
net/core/rtnetlink.c | 67
1 file changed, 67 insertions(+)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 56af8e41abfc..df2363f28574 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1951,6 +1951,57 @@ static struct net *rtnl_link_get_net_capable(const
struct sk_buff *skb,
return net;
}
+/* Verify that rtnetlink requests supporting network namespace ids
+ * do not pass additional properties referring to different network
+ * namespaces.
+ */
+static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
+struct nlattr *tb[],
+struct netlink_ext_ack *extack)
+{
+ int ret = -EINVAL;
+ struct net *net = NULL, *unique_net = NULL;
+
+ /* Requests without network namespace ids have been able to specify
+* multiple properties referring to different network namespaces so
+* don't regress them.
+*/
+ if (!tb[IFLA_IF_NETNSID])
+ return 0;
+
+ if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
+ return 0;
+
+ unique_net = get_net_ns_by_id(sock_net(sk),
nla_get_s32(tb[IFLA_IF_NETNSID]));
+ if (!unique_net)
+ return -1;
+
+ if (tb[IFLA_NET_NS_PID]) {
+ net = get_net_ns_by_pid(nla_get_u32(tb[IFLA_NET_NS_PID]));
+ if (net != unique_net)
+ goto on_error;
+ }
+
+ if (tb[IFLA_NET_NS_FD]) {
+ net = get_net_ns_by_fd(nla_get_u32(tb[IFLA_NET_NS_FD]));
+ if (net != unique_net)
+ goto on_error;
+ }
+
+ ret = 0;
+
+on_error:
+ put_net(unique_net);
+
+ if (net && !IS_ERR(net))
+ put_net(net);
+
+ if (ret != 0)
+ NL_SET_ERR_MSG(extack, "multiple network namespaces specified");
+
+ return ret;
+}
+
static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[])
{
if (dev) {
@@ -2553,6 +2604,10 @@ static int rtnl_setlink(struct sk_buff *skb, struct
nlmsghdr *nlh,
if (err < 0)
goto errout;
+ err = rtnl_ensure_unique_netns_attr(NETLINK_CB(skb).sk, tb, extack);
+ if (err < 0)
+ goto errout;
+
if (tb[IFLA_IFNAME])
nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
else
@@ -2649,6 +2704,10 @@ static int rtnl_dellink(struct sk_buff *skb, struct
nlmsghdr *nlh,
if (err < 0)
return err;
+ err = rtnl_ensure_unique_netns_attr(NETLINK_CB(skb).sk, tb, extack);
+ if (err < 0)
+ return err;
+
if (tb[IFLA_IFNAME])
nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
@@ -2802,6 +2861,10 @@ static int rtnl_newlink(struct sk_buff *skb, struct
nlmsghdr *nlh,
if (err < 0)
return err;
+ err = rtnl_ensure_unique_netns_attr(NETLINK_CB(skb).sk, tb, extack);
+ if (err < 0)
+ return err;
+
if (tb[IFLA_IFNAME])
nla_strlcpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
else
@@ -3045,6 +3108,10 @@ static int rtnl_getlink(struct sk_buff *skb, struct
nlmsghdr *nlh,
if (err < 0)
return err;
+ err = rtnl_ensure_unique_netns_attr(NETLINK_CB(skb).sk, tb, extack);
+ if (err < 0)
+ return err;
+
if (tb[IFLA_IF_NETNSID]) {
netnsid = nla_get_s32(tb[IFLA_IF_NETNSID]);
tgt_net = get_target_net(NETLINK_CB(skb).sk, netnsid);
--
2.14.1
