[Devel] [PATCH rh7] netfilter: Allow xt_owner in any user namespace

Konstantin Khorenko khorenko at virtuozzo.com
Tue Oct 17 19:16:53 MSK 2017


On 10/17/2017 12:08 PM, Stanislav Kinsburskiy wrote:
>
>
> 17.10.2017 08:53, Andrei Vagin пишет:
>> On Mon, Oct 16, 2017 at 05:50:38PM +0200, Stanislav Kinsburskiy wrote:
>>> Well, patch looks ok.
>>> But shouldn't all the ve_init_user_ns() replaced by the par->net?
>>
>> This patch does this.
>>
>
> Yes, but not everywhere.
> Say, there are owner_mt_ve0 and owner_mt6_ve0.
> Shouldn't there functions also patched?

Seems so.
It's needed for old iptables userspace support (iptables-1.3.5 CentOS 5).

Andrey, please send an incremental patch for it.
(and owner_mt_check_v0()/owner_mt6_check_v0() are to be enhanced with uid validness check as well i suppose)


commit cf3bb0a2da9940cd534d486c778f9d1d6728e26c
Author: Kirill Tkhai <ktkhai at parallels.com>
Date:   Wed Oct 8 13:41:09 2014 +0400

     ve/netfilter: Restore revision 0 "owner" match support

     Rebasing and splitting netfilters sybsystem
     (port 66-diff-ve-net-netfilter-combined).
     Part 1.

     https://jira.sw.ru/browse/PSBM-18322

     Revision 0 is still used in our VE templates (iptables-1.3.5)
     so we just can't drop this kind of support. Bring them back.

     Restore version 0 of match "owner",
     which was deleted from mainstream.

     Signed-off-by: Kirill Tkhai <ktkhai at parallels.com>


>
>>>
>>> 14.10.2017 01:20, Andrei Vagin пишет:
>>>> From: "Eric W. Biederman" <ebiederm at xmission.com>
>>>>
>>>> ML: 9847371a84b0be330f4bc4aaa98904101ee8573d
>>>> https://jira.sw.ru/browse/PSBM-69409?
>>>>
>>>> Making this work is a little tricky as it really isn't kosher to
>>>> change the xt_owner_match_info in a check function.
>>>>
>>>> Without changing xt_owner_match_info we need to know the user
>>>> namespace the uids and gids are specified in.  In the common case
>>>> net->user_ns == current_user_ns().  Verify net->user_ns ==
>>>> current_user_ns() in owner_check so we can later assume it in
>>>> owner_mt.
>>>>
>>>> In owner_check also verify that all of the uids and gids specified are
>>>> in net->user_ns and that the expected min/max relationship exists
>>>> between the uids and gids in xt_owner_match_info.
>>>>
>>>> In owner_mt get the network namespace from the outgoing socket, as this
>>>> must be the same network namespace as the netfilter rules, and use that
>>>> network namespace to find the user namespace the uids and gids in
>>>> xt_match_owner_info are encoded in.  Then convert from their encoded
>>>> from into the kernel internal format for uids and gids and perform the
>>>> owner match.
>>>>
>>>> Similar to ping_group_range, this code does not try to detect
>>>> noncontiguous UID/GID ranges.
>>>>
>>>> Signed-off-by: "Eric W. Biederman" <ebiederm at xmission.com>
>>>> Signed-off-by: Kevin Cernekee <cernekee at chromium.org>
>>>> Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
>>>> Signed-off-by: Andrei Vagin <avagin at virtuozzo.com>
>>>> ---
>>>>  net/netfilter/xt_owner.c | 41 +++++++++++++++++++++++++++++++++++------
>>>>  1 file changed, 35 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/net/netfilter/xt_owner.c b/net/netfilter/xt_owner.c
>>>> index 31dec4a..1744f78 100644
>>>> --- a/net/netfilter/xt_owner.c
>>>> +++ b/net/netfilter/xt_owner.c
>>>> @@ -80,11 +80,39 @@ owner_mt6_v0(const struct sk_buff *skb, struct xt_action_param *par)
>>>>  static int owner_check(const struct xt_mtchk_param *par)
>>>>  {
>>>>  	struct xt_owner_match_info *info = par->matchinfo;
>>>> +	struct net *net = par->net;
>>>>
>>>> -	/* For now only allow adding matches from the initial user namespace */
>>>> +	/* Only allow the common case where the userns of the writer
>>>> +	 * matches the userns of the network namespace.
>>>> +	 */
>>>>  	if ((info->match & (XT_OWNER_UID|XT_OWNER_GID)) &&
>>>> -	    !current_user_ns_initial())
>>>> +	    (current_user_ns() != net->user_ns))
>>>>  		return -EINVAL;
>>>> +
>>>> +	/* Ensure the uids are valid */
>>>> +	if (info->match & XT_OWNER_UID) {
>>>> +		kuid_t uid_min = make_kuid(net->user_ns, info->uid_min);
>>>> +		kuid_t uid_max = make_kuid(net->user_ns, info->uid_max);
>>>> +
>>>> +		if (!uid_valid(uid_min) || !uid_valid(uid_max) ||
>>>> +		    (info->uid_max < info->uid_min) ||
>>>> +		    uid_lt(uid_max, uid_min)) {
>>>> +			return -EINVAL;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	/* Ensure the gids are valid */
>>>> +	if (info->match & XT_OWNER_GID) {
>>>> +		kgid_t gid_min = make_kgid(net->user_ns, info->gid_min);
>>>> +		kgid_t gid_max = make_kgid(net->user_ns, info->gid_max);
>>>> +
>>>> +		if (!gid_valid(gid_min) || !gid_valid(gid_max) ||
>>>> +		    (info->gid_max < info->gid_min) ||
>>>> +		    gid_lt(gid_max, gid_min)) {
>>>> +			return -EINVAL;
>>>> +		}
>>>> +	}
>>>> +
>>>>  	return 0;
>>>>  }
>>>>
>>>> @@ -93,6 +121,7 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
>>>>  {
>>>>  	const struct xt_owner_match_info *info = par->matchinfo;
>>>>  	const struct file *filp;
>>>> +	struct net *net = dev_net(par->in ? par->in : par->out);
>>>>
>>>>  	if (skb->sk == NULL || skb->sk->sk_socket == NULL)
>>>>  		return (info->match ^ info->invert) == 0;
>>>> @@ -109,8 +138,8 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
>>>>  		       (XT_OWNER_UID | XT_OWNER_GID)) == 0;
>>>>
>>>>  	if (info->match & XT_OWNER_UID) {
>>>> -		kuid_t uid_min = make_kuid(ve_init_user_ns(), info->uid_min);
>>>> -		kuid_t uid_max = make_kuid(ve_init_user_ns(), info->uid_max);
>>>> +		kuid_t uid_min = make_kuid(net->user_ns, info->uid_min);
>>>> +		kuid_t uid_max = make_kuid(net->user_ns, info->uid_max);
>>>>  		if ((uid_gte(filp->f_cred->fsuid, uid_min) &&
>>>>  		     uid_lte(filp->f_cred->fsuid, uid_max)) ^
>>>>  		    !(info->invert & XT_OWNER_UID))
>>>> @@ -118,8 +147,8 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
>>>>  	}
>>>>
>>>>  	if (info->match & XT_OWNER_GID) {
>>>> -		kgid_t gid_min = make_kgid(ve_init_user_ns(), info->gid_min);
>>>> -		kgid_t gid_max = make_kgid(ve_init_user_ns(), info->gid_max);
>>>> +		kgid_t gid_min = make_kgid(net->user_ns, info->gid_min);
>>>> +		kgid_t gid_max = make_kgid(net->user_ns, info->gid_max);
>>>>  		if ((gid_gte(filp->f_cred->fsgid, gid_min) &&
>>>>  		     gid_lte(filp->f_cred->fsgid, gid_max)) ^
>>>>  		    !(info->invert & XT_OWNER_GID))
>>>>
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