android-mainline/ANDROID-Temporarily-disable-XFRM_USER_COMPAT-filtering.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Alistair Delva <adelva@google.com>
Date: Thu, 5 Nov 2020 08:49:49 -0800
Subject: ANDROID: Temporarily disable XFRM_USER_COMPAT filtering

Before 5.10-rc1, the upstream kernel blocked any compat calls into XFRM
code with EOPNOTSUPP, however Android kernels had been patching this
check out and made userspace match the 64-bit kernel netlink format
instead.

When the new XFRM_USER_COMPAT feature landed, it added a similar check
in two places which returns EOPNOTSUPP only if the XFRM_USER_COMPAT
feature is disabled, however that is currently always the case for
Android kernels and we do not want to filter these callers.

While we work to remove the userspace compatibility mess, disable the
filtering of compat calls when XFRM_USER_COMPAT is disabled. If the
XFRM_USER_COMPAT feature is enabled, nothing changes.

[CPNOTE: 20/07/21] Lee: Pinged the author via the bug

Bug: 163141236
Bug: 172541864
Signed-off-by: Alistair Delva <adelva@google.com>
Change-Id: Ifbea109070650dfcb4f93a3cc692c18a8d11ab44
---
 net/xfrm/xfrm_state.c | 27 +++++++++++++++------------
 net/xfrm/xfrm_user.c  | 29 ++++++++++++++++-------------
 2 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2412,19 +2412,22 @@ int xfrm_user_policy(struct sock *sk, int optname, sockptr_t optval, int optlen)
 	if (IS_ERR(data))
 		return PTR_ERR(data);
 
-	if (in_compat_syscall()) {
-		struct xfrm_translator *xtr = xfrm_get_translator();
-
-		if (!xtr) {
-			kfree(data);
-			return -EOPNOTSUPP;
-		}
+	/* Use the 64-bit / untranslated format on Android, even for compat */
+	if (!IS_ENABLED(CONFIG_ANDROID) || IS_ENABLED(CONFIG_XFRM_USER_COMPAT)) {
+		if (in_compat_syscall()) {
+			struct xfrm_translator *xtr = xfrm_get_translator();
+
+			if (!xtr) {
+				kfree(data);
+				return -EOPNOTSUPP;
+			}
 
-		err = xtr->xlate_user_policy_sockptr(&data, optlen);
-		xfrm_put_translator(xtr);
-		if (err) {
-			kfree(data);
-			return err;
+			err = xtr->xlate_user_policy_sockptr(&data, optlen);
+			xfrm_put_translator(xtr);
+			if (err) {
+				kfree(data);
+				return err;
+			}
 		}
 	}
 
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2865,19 +2865,22 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (!netlink_net_capable(skb, CAP_NET_ADMIN))
 		return -EPERM;
 
-	if (in_compat_syscall()) {
-		struct xfrm_translator *xtr = xfrm_get_translator();
-
-		if (!xtr)
-			return -EOPNOTSUPP;
-
-		nlh64 = xtr->rcv_msg_compat(nlh, link->nla_max,
-					    link->nla_pol, extack);
-		xfrm_put_translator(xtr);
-		if (IS_ERR(nlh64))
-			return PTR_ERR(nlh64);
-		if (nlh64)
-			nlh = nlh64;
+	/* Use the 64-bit / untranslated format on Android, even for compat */
+	if (!IS_ENABLED(CONFIG_ANDROID) || IS_ENABLED(CONFIG_XFRM_USER_COMPAT)) {
+		if (in_compat_syscall()) {
+			struct xfrm_translator *xtr = xfrm_get_translator();
+
+			if (!xtr)
+				return -EOPNOTSUPP;
+
+			nlh64 = xtr->rcv_msg_compat(nlh, link->nla_max,
+						    link->nla_pol, extack);
+			xfrm_put_translator(xtr);
+			if (IS_ERR(nlh64))
+				return PTR_ERR(nlh64);
+			if (nlh64)
+				nlh = nlh64;
+		}
 	}
 
 	if ((type == (XFRM_MSG_GETSA - XFRM_MSG_BASE) ||