Patch "xfrm: Reject optional tunnel/BEET mode templates in outbound policies" has been added to the 6.3-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    xfrm: Reject optional tunnel/BEET mode templates in outbound policies

to the 6.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xfrm-reject-optional-tunnel-beet-mode-templates-in-o.patch
and it can be found in the queue-6.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 49081db475ee0511d01931eb6c8fa37e3ff78f7a
Author: Tobias Brunner <tobias@xxxxxxxxxxxxxx>
Date:   Tue May 9 10:59:58 2023 +0200

    xfrm: Reject optional tunnel/BEET mode templates in outbound policies
    
    [ Upstream commit 3d776e31c841ba2f69895d2255a49320bec7cea6 ]
    
    xfrm_state_find() uses `encap_family` of the current template with
    the passed local and remote addresses to find a matching state.
    If an optional tunnel or BEET mode template is skipped in a mixed-family
    scenario, there could be a mismatch causing an out-of-bounds read as
    the addresses were not replaced to match the family of the next template.
    
    While there are theoretical use cases for optional templates in outbound
    policies, the only practical one is to skip IPComp states in inbound
    policies if uncompressed packets are received that are handled by an
    implicitly created IPIP state instead.
    
    Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
    Signed-off-by: Tobias Brunner <tobias@xxxxxxxxxxxxxx>
    Acked-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index af8fbcbfbe691..6794b9dea27aa 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1768,7 +1768,7 @@ static void copy_templates(struct xfrm_policy *xp, struct xfrm_user_tmpl *ut,
 }
 
 static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family,
-			 struct netlink_ext_ack *extack)
+			 int dir, struct netlink_ext_ack *extack)
 {
 	u16 prev_family;
 	int i;
@@ -1794,6 +1794,10 @@ static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family,
 		switch (ut[i].mode) {
 		case XFRM_MODE_TUNNEL:
 		case XFRM_MODE_BEET:
+			if (ut[i].optional && dir == XFRM_POLICY_OUT) {
+				NL_SET_ERR_MSG(extack, "Mode in optional template not allowed in outbound policy");
+				return -EINVAL;
+			}
 			break;
 		default:
 			if (ut[i].family != prev_family) {
@@ -1831,7 +1835,7 @@ static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family,
 }
 
 static int copy_from_user_tmpl(struct xfrm_policy *pol, struct nlattr **attrs,
-			       struct netlink_ext_ack *extack)
+			       int dir, struct netlink_ext_ack *extack)
 {
 	struct nlattr *rt = attrs[XFRMA_TMPL];
 
@@ -1842,7 +1846,7 @@ static int copy_from_user_tmpl(struct xfrm_policy *pol, struct nlattr **attrs,
 		int nr = nla_len(rt) / sizeof(*utmpl);
 		int err;
 
-		err = validate_tmpl(nr, utmpl, pol->family, extack);
+		err = validate_tmpl(nr, utmpl, pol->family, dir, extack);
 		if (err)
 			return err;
 
@@ -1919,7 +1923,7 @@ static struct xfrm_policy *xfrm_policy_construct(struct net *net,
 	if (err)
 		goto error;
 
-	if (!(err = copy_from_user_tmpl(xp, attrs, extack)))
+	if (!(err = copy_from_user_tmpl(xp, attrs, p->dir, extack)))
 		err = copy_from_user_sec_ctx(xp, attrs);
 	if (err)
 		goto error;
@@ -3498,7 +3502,7 @@ static struct xfrm_policy *xfrm_compile_policy(struct sock *sk, int opt,
 		return NULL;
 
 	nr = ((len - sizeof(*p)) / sizeof(*ut));
-	if (validate_tmpl(nr, ut, p->sel.family, NULL))
+	if (validate_tmpl(nr, ut, p->sel.family, p->dir, NULL))
 		return NULL;
 
 	if (p->dir > XFRM_POLICY_OUT)