Commit 2d151d39 authored by Steffen Klassert's avatar Steffen Klassert
Browse files

xfrm: Add possibility to set the default to block if we have no policy 



As the default we assume the traffic to pass, if we have no
matching IPsec policy. With this patch, we have a possibility to
change this default from allow to block. It can be configured
via netlink. Each direction (input/output/forward) can be
configured separately. With the default to block configuered,
we need allow policies for all packet flows we accept.
We do not use default policy lookup for the loopback device.

v1->v2
 - fix compiling when XFRM is disabled
 - Reported-by: default avatarkernel test robot <lkp@intel.com>

Co-developed-by: default avatarChristian Langrock <christian.langrock@secunet.com>
Signed-off-by: default avatarChristian Langrock <christian.langrock@secunet.com>
Co-developed-by: default avatarAntony Antony <antony.antony@secunet.com>
Signed-off-by: default avatarAntony Antony <antony.antony@secunet.com>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent f8fdadef

include/net/netns/xfrm.h

+7 −0
Original line number Diff line number Diff line
@@ -65,6 +65,13 @@ struct netns_xfrm { 
	u32			sysctl_aevent_rseqth;

	int			sysctl_larval_drop;

	u32			sysctl_acq_expires;



	u8			policy_default;

#define XFRM_POL_DEFAULT_IN	1

#define XFRM_POL_DEFAULT_OUT	2

#define XFRM_POL_DEFAULT_FWD	4

#define XFRM_POL_DEFAULT_MASK	7



#ifdef CONFIG_SYSCTL

	struct ctl_table_header	*sysctl_hdr;

#endif

include/net/xfrm.h

+30 −6
Original line number Diff line number Diff line
@@ -1075,6 +1075,22 @@ xfrm_state_addr_cmp(const struct xfrm_tmpl *tmpl, const struct xfrm_state *x, un 
}



#ifdef CONFIG_XFRM

static inline bool

xfrm_default_allow(struct net *net, int dir)

{

	u8 def = net->xfrm.policy_default;



	switch (dir) {

	case XFRM_POLICY_IN:

		return def & XFRM_POL_DEFAULT_IN ? false : true;

	case XFRM_POLICY_OUT:

		return def & XFRM_POL_DEFAULT_OUT ? false : true;

	case XFRM_POLICY_FWD:

		return def & XFRM_POL_DEFAULT_FWD ? false : true;

	}

	return false;

}



int __xfrm_policy_check(struct sock *, int dir, struct sk_buff *skb,

			unsigned short family);
@@ -1088,9 +1104,13 @@ static inline int __xfrm_policy_check2(struct sock *sk, int dir, 
	if (sk && sk->sk_policy[XFRM_POLICY_IN])

		return __xfrm_policy_check(sk, ndir, skb, family);



	if (xfrm_default_allow(net, dir))

		return (!net->xfrm.policy_count[dir] && !secpath_exists(skb)) ||

		       (skb_dst(skb) && (skb_dst(skb)->flags & DST_NOPOLICY)) ||

		       __xfrm_policy_check(sk, ndir, skb, family);

	else

		return (skb_dst(skb) && (skb_dst(skb)->flags & DST_NOPOLICY)) ||

		       __xfrm_policy_check(sk, ndir, skb, family);

}



static inline int xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, unsigned short family)
@@ -1142,9 +1162,13 @@ static inline int xfrm_route_forward(struct sk_buff *skb, unsigned short family) 
{

	struct net *net = dev_net(skb->dev);



	if (xfrm_default_allow(net, XFRM_POLICY_FWD))

		return !net->xfrm.policy_count[XFRM_POLICY_OUT] ||

			(skb_dst(skb)->flags & DST_NOXFRM) ||

			__xfrm_route_forward(skb, family);

	else

		return (skb_dst(skb)->flags & DST_NOXFRM) ||

			__xfrm_route_forward(skb, family);

}



static inline int xfrm4_route_forward(struct sk_buff *skb)

include/uapi/linux/xfrm.h

+10 −0
Original line number Diff line number Diff line
@@ -213,6 +213,11 @@ enum { 
	XFRM_MSG_GETSPDINFO,

#define XFRM_MSG_GETSPDINFO XFRM_MSG_GETSPDINFO



	XFRM_MSG_SETDEFAULT,

#define XFRM_MSG_SETDEFAULT XFRM_MSG_SETDEFAULT

	XFRM_MSG_GETDEFAULT,

#define XFRM_MSG_GETDEFAULT XFRM_MSG_GETDEFAULT



	XFRM_MSG_MAPPING,

#define XFRM_MSG_MAPPING XFRM_MSG_MAPPING

	__XFRM_MSG_MAX
@@ -508,6 +513,11 @@ struct xfrm_user_offload { 
#define XFRM_OFFLOAD_IPV6	1

#define XFRM_OFFLOAD_INBOUND	2



struct xfrm_userpolicy_default {

	__u8				dirmask;

	__u8				action;

};



#ifndef __KERNEL__

/* backwards compatibility for userspace */

#define XFRMGRP_ACQUIRE		1

net/xfrm/xfrm_policy.c

+16 −0
Original line number Diff line number Diff line
@@ -3165,6 +3165,11 @@ struct dst_entry *xfrm_lookup_with_ifid(struct net *net, 
	return dst;



nopol:

	if (!(dst_orig->dev->flags & IFF_LOOPBACK) &&

	    !xfrm_default_allow(net, dir)) {

		err = -EPERM;

		goto error;

	}

	if (!(flags & XFRM_LOOKUP_ICMP)) {

		dst = dst_orig;

		goto ok;
@@ -3553,6 +3558,11 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, 
	}



	if (!pol) {

		if (!xfrm_default_allow(net, dir)) {

			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOPOLS);

			return 0;

		}



		if (sp && secpath_has_nontransport(sp, 0, &xerr_idx)) {

			xfrm_secpath_reject(xerr_idx, skb, &fl);

			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOPOLS);
@@ -3607,6 +3617,12 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb, 
				tpp[ti++] = &pols[pi]->xfrm_vec[i];

		}

		xfrm_nr = ti;



		if (!xfrm_default_allow(net, dir) && !xfrm_nr) {

			XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOSTATES);

			goto reject;

		}



		if (npols > 1) {

			xfrm_tmpl_sort(stp, tpp, xfrm_nr, family);

			tpp = stp;

net/xfrm/xfrm_user.c

+52 −0
Original line number Diff line number Diff line
@@ -1961,6 +1961,54 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb, 
	return skb;

}



static int xfrm_set_default(struct sk_buff *skb, struct nlmsghdr *nlh,

			    struct nlattr **attrs)

{

	struct net *net = sock_net(skb->sk);

	struct xfrm_userpolicy_default *up = nlmsg_data(nlh);

	u8 dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK;

	u8 old_default = net->xfrm.policy_default;



	net->xfrm.policy_default = (old_default & (0xff ^ dirmask))

				    | (up->action << up->dirmask);



	rt_genid_bump_all(net);



	return 0;

}



static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh,

			    struct nlattr **attrs)

{

	struct sk_buff *r_skb;

	struct nlmsghdr *r_nlh;

	struct net *net = sock_net(skb->sk);

	struct xfrm_userpolicy_default *r_up, *up;

	int len = NLMSG_ALIGN(sizeof(struct xfrm_userpolicy_default));

	u32 portid = NETLINK_CB(skb).portid;

	u32 seq = nlh->nlmsg_seq;



	up = nlmsg_data(nlh);



	r_skb = nlmsg_new(len, GFP_ATOMIC);

	if (!r_skb)

		return -ENOMEM;



	r_nlh = nlmsg_put(r_skb, portid, seq, XFRM_MSG_GETDEFAULT, sizeof(*r_up), 0);

	if (!r_nlh) {

		kfree_skb(r_skb);

		return -EMSGSIZE;

	}



	r_up = nlmsg_data(r_nlh);



	r_up->action = ((net->xfrm.policy_default & (1 << up->dirmask)) >> up->dirmask);

	r_up->dirmask = up->dirmask;

	nlmsg_end(r_skb, r_nlh);



	return nlmsg_unicast(net->xfrm.nlsk, r_skb, portid);

}



static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,

		struct nlattr **attrs)

{
@@ -2664,6 +2712,8 @@ const int xfrm_msg_min[XFRM_NR_MSGTYPES] = { 
	[XFRM_MSG_GETSADINFO  - XFRM_MSG_BASE] = sizeof(u32),

	[XFRM_MSG_NEWSPDINFO  - XFRM_MSG_BASE] = sizeof(u32),

	[XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = sizeof(u32),

	[XFRM_MSG_SETDEFAULT  - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_default),

	[XFRM_MSG_GETDEFAULT  - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_default),

};

EXPORT_SYMBOL_GPL(xfrm_msg_min);
@@ -2743,6 +2793,8 @@ static const struct xfrm_link { 
						   .nla_pol = xfrma_spd_policy,

						   .nla_max = XFRMA_SPD_MAX },

	[XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = { .doit = xfrm_get_spdinfo   },

	[XFRM_MSG_SETDEFAULT  - XFRM_MSG_BASE] = { .doit = xfrm_set_default   },

	[XFRM_MSG_GETDEFAULT  - XFRM_MSG_BASE] = { .doit = xfrm_get_default   },

};



static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,