xfrm: policy: match with both mark and mask on user interfaces

BugLink: https://bugs.launchpad.net/bugs/1890796

In commit ed17b8d3 ("xfrm: fix a warning in xfrm_policy_insert_list"),
it would take 'priority' to make a policy unique, and allow duplicated
policies with different 'priority' to be added, which is not expected
by userland, as Tobias reported in strongswan.

To fix this duplicated policies issue, and also fix the issue in
commit ed17b8d3 ("xfrm: fix a warning in xfrm_policy_insert_list"),
when doing add/del/get/update on user interfaces, this patch is to change
to look up a policy with both mark and mask by doing:

  mark.v == pol->mark.v && mark.m == pol->mark.m

and leave the check:

  (mark & pol->mark.m) == pol->mark.v

for tx/rx path only.

As the userland expects an exact mark and mask match to manage policies.

v1->v2:
  - make xfrm_policy_mark_match inline and fix the changelog as
    Tobias suggested.

Fixes: 295fae56 ("xfrm: Allow user space manipulation of SPD mark")
Fixes: ed17b8d3 ("xfrm: fix a warning in xfrm_policy_insert_list")
Reported-by: Tobias Brunner <tobias@strongswan.org>
Tested-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

(backported from commit 4f47e8ab)
[smb: work around missing if_id parameter and __xfrm_policy_bysel_ctx]
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>

include/net/xfrm.h

@@ -1599,13 +1599,15 @@ int xfrm_policy_walk(struct net *net, struct xfrm_policy_walk *walk,
 		     void *);
 void xfrm_policy_walk_done(struct xfrm_policy_walk *walk, struct net *net);
 int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl);
-struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark,
+struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net,
+					  const struct xfrm_mark *mark,
 					  u8 type, int dir,
 					  struct xfrm_selector *sel,
 					  struct xfrm_sec_ctx *ctx, int delete,
 					  int *err);
-struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u8, int dir,
-				     u32 id, int delete, int *err);
+struct xfrm_policy *xfrm_policy_byid(struct net *net,
+				     const struct xfrm_mark *mark, u8,
+				     int dir, u32 id, int delete, int *err);
 int xfrm_policy_flush(struct net *net, u8 type, bool task_valid);
 void xfrm_policy_hash_rebuild(struct net *net);
 u32 xfrm_get_acqseq(void);

net/key/af_key.c

@@ -2427,7 +2427,7 @@ static int pfkey_spddelete(struct sock *sk, struct sk_buff *skb, const struct sa
 			return err;
 	}
 
-	xp = xfrm_policy_bysel_ctx(net, DUMMY_MARK, XFRM_POLICY_TYPE_MAIN,
+	xp = xfrm_policy_bysel_ctx(net, &dummy_mark, XFRM_POLICY_TYPE_MAIN,
 				   pol->sadb_x_policy_dir - 1, &sel, pol_ctx,
 				   1, &err);
 	security_xfrm_policy_free(pol_ctx);
@@ -2680,7 +2680,7 @@ static int pfkey_spdget(struct sock *sk, struct sk_buff *skb, const struct sadb_
 		return -EINVAL;
 
 	delete = (hdr->sadb_msg_type == SADB_X_SPDDELETE2);
-	xp = xfrm_policy_byid(net, DUMMY_MARK, XFRM_POLICY_TYPE_MAIN,
+	xp = xfrm_policy_byid(net, &dummy_mark, XFRM_POLICY_TYPE_MAIN,
 			      dir, pol->sadb_x_policy_id, delete, &err);
 	if (xp == NULL)
 		return -ENOENT;

net/xfrm/xfrm_policy.c

@@ -737,14 +737,10 @@ static void xfrm_policy_requeue(struct xfrm_policy *old,
 	spin_unlock_bh(&pq->hold_queue.lock);
 }
 
-static bool xfrm_policy_mark_match(struct xfrm_policy *policy,
-				   struct xfrm_policy *pol)
+static inline bool xfrm_policy_mark_match(const struct xfrm_mark *mark,
+					  struct xfrm_policy *pol)
 {
-	if (policy->mark.v == pol->mark.v &&
-	    policy->priority == pol->priority)
-		return true;
-
-	return false;
+	return mark->v == pol->mark.v && mark->m == pol->mark.m;
 }
 
 int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
@@ -762,7 +758,7 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
 	hlist_for_each_entry(pol, chain, bydst) {
 		if (pol->type == policy->type &&
 		    !selector_cmp(&pol->selector, &policy->selector) &&
-		    xfrm_policy_mark_match(policy, pol) &&
+		    xfrm_policy_mark_match(&policy->mark, pol) &&
 		    xfrm_sec_ctx_match(pol->security, policy->security) &&
 		    !WARN_ON(delpol)) {
 			if (excl) {
@@ -813,10 +809,10 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl)
 }
 EXPORT_SYMBOL(xfrm_policy_insert);
 
-struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
-					  int dir, struct xfrm_selector *sel,
-					  struct xfrm_sec_ctx *ctx, int delete,
-					  int *err)
+struct xfrm_policy *
+xfrm_policy_bysel_ctx(struct net *net, const struct xfrm_mark *mark, u8 type,
+		      int dir, struct xfrm_selector *sel,
+		      struct xfrm_sec_ctx *ctx, int delete, int *err)
 {
 	struct xfrm_policy *pol, *ret;
 	struct hlist_head *chain;
@@ -827,7 +823,7 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
 	ret = NULL;
 	hlist_for_each_entry(pol, chain, bydst) {
 		if (pol->type == type &&
-		    (mark & pol->mark.m) == pol->mark.v &&
+		    xfrm_policy_mark_match(mark, pol) &&
 		    !selector_cmp(sel, &pol->selector) &&
 		    xfrm_sec_ctx_match(ctx, pol->security)) {
 			xfrm_pol_hold(pol);
@@ -852,8 +848,9 @@ struct xfrm_policy *xfrm_policy_bysel_ctx(struct net *net, u32 mark, u8 type,
 }
 EXPORT_SYMBOL(xfrm_policy_bysel_ctx);
 
-struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u8 type,
-				     int dir, u32 id, int delete, int *err)
+struct xfrm_policy *
+xfrm_policy_byid(struct net *net, const struct xfrm_mark *mark, u8 type,
+		 int dir, u32 id, int delete, int *err)
 {
 	struct xfrm_policy *pol, *ret;
 	struct hlist_head *chain;
@@ -868,7 +865,7 @@ struct xfrm_policy *xfrm_policy_byid(struct net *net, u32 mark, u8 type,
 	ret = NULL;
 	hlist_for_each_entry(pol, chain, byidx) {
 		if (pol->type == type && pol->index == id &&
-		    (mark & pol->mark.m) == pol->mark.v) {
+		    xfrm_policy_mark_match(mark, pol)) {
 			xfrm_pol_hold(pol);
 			if (delete) {
 				*err = security_xfrm_policy_delete(

net/xfrm/xfrm_user.c

@@ -1776,7 +1776,6 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 	struct km_event c;
 	int delete;
 	struct xfrm_mark m;
-	u32 mark = xfrm_mark_get(attrs, &m);
 
 	p = nlmsg_data(nlh);
 	delete = nlh->nlmsg_type == XFRM_MSG_DELPOLICY;
@@ -1789,8 +1788,11 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		return err;
 
+	xfrm_mark_get(attrs, &m);
+
 	if (p->index)
-		xp = xfrm_policy_byid(net, mark, type, p->dir, p->index, delete, &err);
+		xp = xfrm_policy_byid(net, &m, type, p->dir, p->index,
+				      delete, &err);
 	else {
 		struct nlattr *rt = attrs[XFRMA_SEC_CTX];
 		struct xfrm_sec_ctx *ctx;
@@ -1807,7 +1809,7 @@ static int xfrm_get_policy(struct sk_buff *skb, struct nlmsghdr *nlh,
 			if (err)
 				return err;
 		}
-		xp = xfrm_policy_bysel_ctx(net, mark, type, p->dir, &p->sel,
+		xp = xfrm_policy_bysel_ctx(net, &m, type, p->dir, &p->sel,
 					   ctx, delete, &err);
 		security_xfrm_policy_free(ctx);
 	}
@@ -2070,7 +2072,6 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 	u8 type = XFRM_POLICY_TYPE_MAIN;
 	int err = -ENOENT;
 	struct xfrm_mark m;
-	u32 mark = xfrm_mark_get(attrs, &m);
 
 	err = copy_from_user_policy_type(&type, attrs);
 	if (err)
@@ -2080,8 +2081,11 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		return err;
 
+	xfrm_mark_get(attrs, &m);
+
 	if (p->index)
-		xp = xfrm_policy_byid(net, mark, type, p->dir, p->index, 0, &err);
+		xp = xfrm_policy_byid(net, &m, type, p->dir, p->index, 0,
+				      &err);
 	else {
 		struct nlattr *rt = attrs[XFRMA_SEC_CTX];
 		struct xfrm_sec_ctx *ctx;
@@ -2098,7 +2102,7 @@ static int xfrm_add_pol_expire(struct sk_buff *skb, struct nlmsghdr *nlh,
 			if (err)
 				return err;
 		}
-		xp = xfrm_policy_bysel_ctx(net, mark, type, p->dir,
+		xp = xfrm_policy_bysel_ctx(net, &m, type, p->dir,
 					   &p->sel, ctx, 0, &err);
 		security_xfrm_policy_free(ctx);
 	}