Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ ipsec-next

Steffen Klassert says:

====================
pull request (net-next): ipsec-next 2021-08-27

1) Remove an unneeded extra variable in esp4 esp_ssg_unref.
From Corey Minyard.

2) Add a configuration option to change the default behaviour
to block traffic if there is no matching policy.
Joint work with Christian Langrock and Antony Antony.

3) Fix a shift-out-of-bounce bug reported from syzbot.
From Pavel Skripkin.

Please pull or let me know if there are problems.
====================

Signed-off-by: David S. Miller <[e-mail]>

include/net/netns/xfrm.h

···
 	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

···
 }
 
 #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);
 
···
 	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)
···
 {
 	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)

include/uapi/linux/xfrm.h

···
 	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
···
 };
 #define XFRM_OFFLOAD_IPV6	1
 #define XFRM_OFFLOAD_INBOUND	2
+
+struct xfrm_userpolicy_default {
+#define XFRM_USERPOLICY_DIRMASK_MAX	(sizeof(__u8) * 8)
+	__u8				dirmask;
+	__u8				action;
+};
 
 #ifndef __KERNEL__
 /* backwards compatibility for userspace */

net/ipv4/esp4.c

···
 
 static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
 {
-	struct esp_output_extra *extra = esp_tmp_extra(tmp);
 	struct crypto_aead *aead = x->data;
 	int extralen = 0;
 	u8 *iv;
···
 	struct scatterlist *sg;
 
 	if (x->props.flags & XFRM_STATE_ESN)
-		extralen += sizeof(*extra);
+		extralen += sizeof(struct esp_output_extra);
 
-	extra = esp_tmp_extra(tmp);
 	iv = esp_tmp_iv(aead, tmp, extralen);
 	req = esp_tmp_req(aead, iv);
 

net/xfrm/xfrm_policy.c

···
 	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;
···
 	}
 
 	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);
···
 				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

···
 	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;
+	u8 old_default = net->xfrm.policy_default;
+
+	if (up->dirmask >= XFRM_USERPOLICY_DIRMASK_MAX)
+		return -EINVAL;
+
+	dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK;
+
+	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)
 {
···
 	[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);
 
···
 						   .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,