diff mbox series

[ipsec-next] xfrm: Add possibility to set the default to block if we have no policy

Message ID 82704b3073447fd7968587e8c570d5f12bd23310.1626426615.git.antony.antony@secunet.com
State Superseded
Headers show
Series [ipsec-next] xfrm: Add possibility to set the default to block if we have no policy | expand

Commit Message

Antony Antony July 16, 2021, 9:15 a.m. UTC 
From: Steffen Klassert <steffen.klassert@secunet.com>

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.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Co-developed-by: Christian Langrock <christian.langrock@secunet.com>
Signed-off-by: Christian Langrock <christian.langrock@secunet.com>
Co-developed-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Antony Antony <antony.antony@secunet.com>
---
 include/net/netns/xfrm.h  |  7 ++++++
 include/net/xfrm.h        | 36 ++++++++++++++++++++++-----
 include/uapi/linux/xfrm.h | 10 ++++++++
 net/xfrm/xfrm_policy.c    | 16 ++++++++++++
 net/xfrm/xfrm_user.c      | 52 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 115 insertions(+), 6 deletions(-)

Comments

kernel test robot July 18, 2021, 3:26 a.m. UTC | #1 
Hi Antony,

I love your patch! Yet something to improve:

[auto build test ERROR on ipsec-next/master]

url:    https://github.com/0day-ci/linux/commits/Antony-Antony/xfrm-Add-possibility-to-set-the-default-to-block-if-we-have-no-policy/20210718-093119
base:   https://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next.git master
config: s390-randconfig-m031-20210718 (attached as .config)
compiler: s390-linux-gcc (GCC) 10.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/5aac4e97776280ef1fbe4c3d16c28833018d0985
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Antony-Antony/xfrm-Add-possibility-to-set-the-default-to-block-if-we-have-no-policy/20210718-093119
        git checkout 5aac4e97776280ef1fbe4c3d16c28833018d0985
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross O=build_dir ARCH=s390 SHELL=/bin/bash net/core/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from net/core/sock.c:127:
   include/net/xfrm.h: In function 'xfrm_default_allow':
>> include/net/xfrm.h:1080:14: error: 'struct net' has no member named 'xfrm'

    1080 |  u8 def = net->xfrm.policy_default;
         |              ^~


vim +1080 include/net/xfrm.h

  1076	
  1077	static inline bool
  1078	xfrm_default_allow(struct net *net, int dir)
  1079	{
> 1080		u8 def = net->xfrm.policy_default;

  1081	
  1082		switch (dir) {
  1083		case XFRM_POLICY_IN:
  1084			return def & XFRM_POL_DEFAULT_IN ? false : true;
  1085		case XFRM_POLICY_OUT:
  1086			return def & XFRM_POL_DEFAULT_OUT ? false : true;
  1087		case XFRM_POLICY_FWD:
  1088			return def & XFRM_POL_DEFAULT_FWD ? false : true;
  1089		}
  1090		return false;
  1091	}
  1092	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index e946366e8ba5..88c647302977 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -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
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index cbff7c2a9724..d9b470d47af1 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1074,6 +1074,22 @@  xfrm_state_addr_cmp(const struct xfrm_tmpl *tmpl, const struct xfrm_state *x, un
 	return !0;
 }
 
+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;
+}
+
 #ifdef CONFIG_XFRM
 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);
 
-	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);
+	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);
 
-	return	!net->xfrm.policy_count[XFRM_POLICY_OUT] ||
-		(skb_dst(skb)->flags & DST_NOXFRM) ||
-		__xfrm_route_forward(skb, family);
+	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)
diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index ffc6a5391bb7..6e8095106192 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h
@@ -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
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 827d84255021..d5cb082e11fc 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -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;
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index b47d613409b7..4eafd1130c3e 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -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,