Revert "ANDROID: eliminate 'CONFIG_GKI_NET_XFRM_HACKS'"

This partially reverts commit 1cf1608b4a.

(https://android-review.googlesource.com/c/kernel/common/+/3216798
 on android-mainline from before 6.12 branch)

We still need this to support XFRM on 32-bit userspace on aarch64,
the Android way to do this involves not doing compat translation.

Bug: 163141236
Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I18db5f1b75b09b254b751bb5eb2843815b88899e

init/Kconfig.gki

@@ -261,6 +261,11 @@ config GKI_TASK_STRUCT_VENDOR_SIZE_MAX
 	  task_struct dynamically when the GKI_DYNAMIC_TASK_STRUCT_SIZE
 	  option is enabled.
 
+config GKI_NET_XFRM_HACKS
+	bool "XFRM changes required by Android"
+	help
+	  Android Networking tests fail without this.
+
 # Atrocities needed for
 # a) building GKI modules in separate tree, or
 # b) building drivers that are not modularizable
@@ -270,6 +275,7 @@ config GKI_TASK_STRUCT_VENDOR_SIZE_MAX
 #
 config GKI_HACKS_TO_FIX
 	bool "GKI Dummy config options"
+	select GKI_NET_XFRM_HACKS
 	select GKI_HIDDEN_CRYPTO_CONFIGS
 	select GKI_HIDDEN_DRM_CONFIGS
 	select GKI_HIDDEN_MCP251XFD_CONFIGS

net/xfrm/xfrm_state.c

@@ -2685,7 +2685,8 @@ 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()) {
+	/* Use the 64-bit / untranslated format on Android, even for compat */
+	if (!IS_ENABLED(CONFIG_GKI_NET_XFRM_HACKS) && in_compat_syscall()) {
 		struct xfrm_translator *xtr = xfrm_get_translator();
 
 		if (!xtr) {

net/xfrm/xfrm_user.c

@@ -3268,7 +3268,8 @@ 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()) {
+	/* Use the 64-bit / untranslated format on Android, even for compat */
+	if (!IS_ENABLED(CONFIG_GKI_NET_XFRM_HACKS) && in_compat_syscall()) {
 		struct xfrm_translator *xtr = xfrm_get_translator();
 
 		if (!xtr)