Re-add Non-GKI Support

Revert "[1.0] Drop Non-GKI Support (tiann#1483)"
This reverts commit 898e9d4.

Revert "Drop some legacy codes (tiann#1981)"

This reverts commit fd09ccf.

kernel/Makefile

@@ -29,6 +29,14 @@ $(warning "KSU_GIT_VERSION not defined! It is better to make KernelSU a git subm
 ccflags-y += -DKSU_VERSION=16
 endif
 
+ifeq ($(shell grep -q " current_sid(void)" $(srctree)/security/selinux/include/objsec.h; echo $$?),0)
+ccflags-y += -DKSU_COMPAT_HAS_CURRENT_SID
+endif
+
+ifeq ($(shell grep -q "struct selinux_state " $(srctree)/security/selinux/include/security.h; echo $$?),0)
+ccflags-y += -DKSU_COMPAT_HAS_SELINUX_STATE
+endif
+
 ifndef KSU_EXPECTED_SIZE
 KSU_EXPECTED_SIZE := 0x033b
 endif
@@ -48,6 +56,13 @@ $(info -- KernelSU Manager signature hash: $(KSU_EXPECTED_HASH))
 ccflags-y += -DEXPECTED_SIZE=$(KSU_EXPECTED_SIZE)
 ccflags-y += -DEXPECTED_HASH=\"$(KSU_EXPECTED_HASH)\"
 
+ifeq ($(shell grep -q "int path_umount" $(srctree)/fs/namespace.c; echo $$?),0)
+ccflags-y += -DKSU_UMOUNT
+else
+$(info -- Did you know you can backport path_umount to fs/namespace.c from 5.9?)
+$(info -- Read: https://kernelsu.org/guide/how-to-integrate-for-non-gki.html#how-to-backport-path-umount)
+endif
+
 ccflags-y += -Wno-implicit-function-declaration -Wno-strict-prototypes -Wno-int-conversion -Wno-gcc-compat
 ccflags-y += -Wno-declaration-after-statement -Wno-unused-function
 

kernel/allowlist.c

@@ -7,7 +7,9 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/version.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 14, 0)
 #include <linux/compiler_types.h>
+#endif
 
 #include "ksu.h"
 #include "klog.h" // IWYU pragma: keep

kernel/arch.h

@@ -18,11 +18,19 @@
 #define __PT_SP_REG sp
 #define __PT_IP_REG pc
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 16, 0)
 #define PRCTL_SYMBOL "__arm64_sys_prctl"
 #define SYS_READ_SYMBOL "__arm64_sys_read"
 #define SYS_NEWFSTATAT_SYMBOL "__arm64_sys_newfstatat"
 #define SYS_FACCESSAT_SYMBOL "__arm64_sys_faccessat"
 #define SYS_EXECVE_SYMBOL "__arm64_sys_execve"
+#else
+#define PRCTL_SYMBOL "sys_prctl"
+#define SYS_READ_SYMBOL "sys_read"
+#define SYS_NEWFSTATAT_SYMBOL "sys_newfstatat"
+#define SYS_FACCESSAT_SYMBOL "sys_faccessat"
+#define SYS_EXECVE_SYMBOL "sys_execve"
+#endif
 
 #elif defined(__x86_64__)
 
@@ -39,11 +47,19 @@
 #define __PT_RC_REG ax
 #define __PT_SP_REG sp
 #define __PT_IP_REG ip
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 16, 0)
 #define PRCTL_SYMBOL "__x64_sys_prctl"
 #define SYS_READ_SYMBOL "__x64_sys_read"
 #define SYS_NEWFSTATAT_SYMBOL "__x64_sys_newfstatat"
 #define SYS_FACCESSAT_SYMBOL "__x64_sys_faccessat"
 #define SYS_EXECVE_SYMBOL "__x64_sys_execve"
+#else
+#define PRCTL_SYMBOL "sys_prctl"
+#define SYS_READ_SYMBOL "sys_read"
+#define SYS_NEWFSTATAT_SYMBOL "sys_newfstatat"
+#define SYS_FACCESSAT_SYMBOL "sys_faccessat"
+#define SYS_EXECVE_SYMBOL "sys_execve"
+#endif
 
 #else
 #error "Unsupported arch"
@@ -67,6 +83,10 @@
 #define PT_REGS_SP(x) (__PT_REGS_CAST(x)->__PT_SP_REG)
 #define PT_REGS_IP(x) (__PT_REGS_CAST(x)->__PT_IP_REG)
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 16, 0)
 #define PT_REAL_REGS(regs) ((struct pt_regs *)PT_REGS_PARM1(regs))
+#else
+#define PT_REAL_REGS(regs) ((regs))
+#endif
 
 #endif

kernel/core_hook.c

@@ -98,7 +98,11 @@ static void setup_groups(struct root_profile *profile, struct cred *cred)
 			put_group_info(group_info);
 			return;
 		}
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 9, 0)
 		group_info->gid[i] = kgid;
+#else
+		GROUP_AT(group_info, i) = kgid;
+#endif
 	}
 
 	groups_sort(group_info);
@@ -445,12 +449,14 @@ static bool should_umount(struct path *path)
 	return false;
 }
 
-static void ksu_umount_mnt(struct path *path, int flags)
+static int ksu_umount_mnt(struct path *path, int flags)
 {
-	int err = path_umount(path, flags);
-	if (err) {
-		pr_info("umount %s failed: %d\n", path->dentry->d_iname, err);
-	}
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0) || defined(KSU_UMOUNT)
+	return path_umount(path, flags);
+#else
+	// TODO: umount for non GKI kernel
+	return -ENOSYS;
+#endif
 }
 
 static void try_umount(const char *mnt, bool check_mnt, int flags)
@@ -471,7 +477,10 @@ static void try_umount(const char *mnt, bool check_mnt, int flags)
 		return;
 	}
 
-	ksu_umount_mnt(&path, flags);
+	err = ksu_umount_mnt(&path, flags);
+	if (err) {
+		pr_warn("umount %s failed: %d\n", mnt, err);
+	}
 }
 
 int ksu_handle_setuid(struct cred *new, const struct cred *old)
@@ -548,8 +557,14 @@ static int handler_pre(struct kprobe *p, struct pt_regs *regs)
 	int option = (int)PT_REGS_PARM1(real_regs);
 	unsigned long arg2 = (unsigned long)PT_REGS_PARM2(real_regs);
 	unsigned long arg3 = (unsigned long)PT_REGS_PARM3(real_regs);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 16, 0)
 	// PRCTL_SYMBOL is the arch-specificed one, which receive raw pt_regs from syscall
 	unsigned long arg4 = (unsigned long)PT_REGS_SYSCALL_PARM4(real_regs);
+#else
+	// PRCTL_SYMBOL is the common one, called by C convention in do_syscall_64
+	// https://elixir.bootlin.com/linux/v4.15.18/source/arch/x86/entry/common.c#L287
+	unsigned long arg4 = (unsigned long)PT_REGS_CCALL_PARM4(real_regs);
+#endif
 	unsigned long arg5 = (unsigned long)PT_REGS_PARM5(real_regs);
 
 	return ksu_handle_prctl(option, arg2, arg3, arg4, arg5);
@@ -609,7 +624,23 @@ static int ksu_task_prctl(int option, unsigned long arg2, unsigned long arg3,
 	ksu_handle_prctl(option, arg2, arg3, arg4, arg5);
 	return -ENOSYS;
 }
-
+// kernel 4.4 and 4.9
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || defined(CONFIG_IS_HW_HISI)
+static int ksu_key_permission(key_ref_t key_ref, const struct cred *cred,
+			      unsigned perm)
+{
+	if (init_session_keyring != NULL) {
+		return 0;
+	}
+	if (strcmp(current->comm, "init")) {
+		// we are only interested in `init` process
+		return 0;
+	}
+	init_session_keyring = cred->session_keyring;
+	pr_info("kernel_compat: got init_session_keyring\n");
+	return 0;
+}
+#endif
 static int ksu_inode_rename(struct inode *old_inode, struct dentry *old_dentry,
 			    struct inode *new_inode, struct dentry *new_dentry)
 {
@@ -627,11 +658,19 @@ static struct security_hook_list ksu_hooks[] = {
 	LSM_HOOK_INIT(task_prctl, ksu_task_prctl),
 	LSM_HOOK_INIT(inode_rename, ksu_inode_rename),
 	LSM_HOOK_INIT(task_fix_setuid, ksu_task_fix_setuid),
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || defined(CONFIG_IS_HW_HISI)
+	LSM_HOOK_INIT(key_permission, ksu_key_permission)
+#endif
 };
 
 void __init ksu_lsm_hook_init(void)
 {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 11, 0)
 	security_add_hooks(ksu_hooks, ARRAY_SIZE(ksu_hooks), "ksu");
+#else
+	// https://elixir.bootlin.com/linux/v4.10.17/source/include/linux/lsm_hooks.h#L1892
+	security_add_hooks(ksu_hooks, ARRAY_SIZE(ksu_hooks));
+#endif
 }
 
 #else

kernel/kernel_compat.c

@@ -1,10 +1,39 @@
 #include <linux/version.h>
 #include <linux/fs.h>
 #include <linux/nsproxy.h>
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 10, 0)
 #include <linux/sched/task.h>
+#else
+#include <linux/sched.h>
+#endif
 #include <linux/uaccess.h>
 #include "klog.h" // IWYU pragma: keep
-#include "kernel_compat.h"
+#include "kernel_compat.h" // Add check Huawei Device
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || defined(CONFIG_IS_HW_HISI)
+#include <linux/key.h>
+#include <linux/errno.h>
+#include <linux/cred.h>
+struct key *init_session_keyring = NULL;
+
+static inline int install_session_keyring(struct key *keyring)
+{
+	struct cred *new;
+	int ret;
+
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+
+	ret = install_session_keyring_to_cred(new, keyring);
+	if (ret < 0) {
+		abort_creds(new);
+		return ret;
+	}
+
+	return commit_creds(new);
+}
+#endif
 
 extern struct task_struct init_task;
 
@@ -50,6 +79,13 @@ void ksu_android_ns_fs_check()
 
 struct file *ksu_filp_open_compat(const char *filename, int flags, umode_t mode)
 {
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || defined(CONFIG_IS_HW_HISI)
+	if (init_session_keyring != NULL && !current_cred()->session_keyring &&
+	    (current->flags & PF_WQ_WORKER)) {
+		pr_info("installing init session keyring for older kernel\n");
+		install_session_keyring(init_session_keyring);
+	}
+#endif
 	// switch mnt_ns even if current is not wq_worker, to ensure what we open is the correct file in android mnt_ns, rather than user created mnt_ns
 	struct ksu_ns_fs_saved saved;
 	if (android_context_saved_enabled) {
@@ -72,17 +108,69 @@ struct file *ksu_filp_open_compat(const char *filename, int flags, umode_t mode)
 ssize_t ksu_kernel_read_compat(struct file *p, void *buf, size_t count,
 			       loff_t *pos)
 {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 14, 0)
 	return kernel_read(p, buf, count, pos);
+#else
+	loff_t offset = pos ? *pos : 0;
+	ssize_t result = kernel_read(p, offset, (char *)buf, count);
+	if (pos && result > 0) {
+		*pos = offset + result;
+	}
+	return result;
+#endif
 }
 
 ssize_t ksu_kernel_write_compat(struct file *p, const void *buf, size_t count,
 				loff_t *pos)
 {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 14, 0)
 	return kernel_write(p, buf, count, pos);
+#else
+	loff_t offset = pos ? *pos : 0;
+	ssize_t result = kernel_write(p, buf, count, offset);
+	if (pos && result > 0) {
+		*pos = offset + result;
+	}
+	return result;
+#endif
 }
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)
 long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 				   long count)
 {
 	return strncpy_from_user_nofault(dst, unsafe_addr, count);
 }
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 3, 0)
+long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
+				   long count)
+{
+	return strncpy_from_unsafe_user(dst, unsafe_addr, count);
+}
+#else
+// Copied from: https://elixir.bootlin.com/linux/v4.9.337/source/mm/maccess.c#L201
+long ksu_strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
+				   long count)
+{
+	mm_segment_t old_fs = get_fs();
+	long ret;
+
+	if (unlikely(count <= 0))
+		return 0;
+
+	set_fs(USER_DS);
+	pagefault_disable();
+	ret = strncpy_from_user(dst, unsafe_addr, count);
+	pagefault_enable();
+	set_fs(old_fs);
+
+	if (ret >= count) {
+		ret = count;
+		dst[ret - 1] = '\0';
+	} else if (ret > 0) {
+		ret++;
+	}
+
+	return ret;
+}
+#endif

kernel/kernel_compat.h

@@ -24,6 +24,10 @@ extern long ksu_strncpy_from_user_nofault(char *dst,
 					  const void __user *unsafe_addr,
 					  long count);
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 10, 0) || defined(CONFIG_IS_HW_HISI)
+extern struct key *init_session_keyring;
+#endif
+
 extern void ksu_android_ns_fs_check();
 extern struct file *ksu_filp_open_compat(const char *filename, int flags,
 					 umode_t mode);

kernel/ksu.c

@@ -94,4 +94,7 @@ module_exit(kernelsu_exit);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("weishu");
 MODULE_DESCRIPTION("Android KernelSU");
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 0, 0)
 MODULE_IMPORT_NS(VFS_internal_I_am_really_a_filesystem_and_am_NOT_a_driver);
+#endif