#include <linux/compiler.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/task_work.h>
#include <linux/thread_info.h>
#include <linux/seccomp.h>
#include <linux/bpf.h>
#include <linux/capability.h>
#include <linux/cred.h>
#include <linux/dcache.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/init_task.h>
#include <linux/kallsyms.h>
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/mm.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/nsproxy.h>
#include <linux/path.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <linux/security.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/uidgid.h>
#include <linux/version.h>
#include <linux/binfmts.h>
#include <linux/tty.h>

#ifdef CONFIG_KSU_SUSFS
#include <linux/susfs.h>
#endif // #ifdef CONFIG_KSU_SUSFS

#ifndef KSU_HAS_PATH_UMOUNT
#include <linux/syscalls.h> // sys_umount (<4.17) & ksys_umount (4.17+)
#endif

#ifdef MODULE
#include <linux/list.h>
#include <linux/irqflags.h>
#include <linux/mm_types.h>
#include <linux/rcupdate.h>
#include <linux/vmalloc.h>
#endif

#include "allowlist.h"
#include "setuid_hook.h"
#include "feature.h"
#include "klog.h" // IWYU pragma: keep
#include "ksu.h"
#include "manager.h"
#include "selinux/selinux.h"
#include "seccomp_cache.h"
#include "supercalls.h"
#ifndef CONFIG_KSU_SUSFS
#include "syscall_hook_manager.h"
#endif
#include "kernel_umount.h"
#include "app_profile.h"

#include "sulog.h"

#ifdef CONFIG_KSU_SUSFS
static inline bool is_some_system_uid(uid_t uid)
{
    uid %= 100000;
    return (uid >= 1000 && uid < 10000);
}

static inline bool is_zygote_isolated_service_uid(uid_t uid)
{
    uid %= 100000;
    return (uid >= 90000 && uid < 100000);
}

static inline bool is_zygote_normal_app_uid(uid_t uid)
{
    uid %= 100000;
    return (uid >= 10000 && uid < 19999);
}

bool susfs_is_umount_for_zygote_system_process_enabled = false;

extern bool susfs_is_umount_for_zygote_iso_service_enabled;
extern u32 susfs_zygote_sid;
#ifdef CONFIG_KSU_SUSFS_SUS_PATH
extern void susfs_run_sus_path_loop(uid_t uid);
#endif // #ifdef CONFIG_KSU_SUSFS_SUS_PATH
#ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
extern void susfs_reorder_mnt_id(void);
#endif // #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
#ifdef CONFIG_KSU_SUSFS_TRY_UMOUNT
extern void susfs_try_umount_all(void);
#endif
#endif // #ifdef CONFIG_KSU_SUSFS

static bool ksu_enhanced_security_enabled = false;

static int enhanced_security_feature_get(u64 *value)
{
    *value = ksu_enhanced_security_enabled ? 1 : 0;
    return 0;
}

static int enhanced_security_feature_set(u64 value)
{
    bool enable = value != 0;
    ksu_enhanced_security_enabled = enable;
    pr_info("enhanced_security: set to %d\n", enable);
    return 0;
}

static const struct ksu_feature_handler enhanced_security_handler = {
    .feature_id = KSU_FEATURE_ENHANCED_SECURITY,
    .name = "enhanced_security",
    .get_handler = enhanced_security_feature_get,
    .set_handler = enhanced_security_feature_set,
};

static inline bool is_allow_su(void)
{
    if (is_manager()) {
        // we are manager, allow!
        return true;
    }
    return ksu_is_allow_uid_for_current(current_uid().val);
}

#ifndef CONFIG_KSU_SUSFS
int ksu_handle_setresuid(uid_t ruid, uid_t euid, uid_t suid)
{
    uid_t new_uid = ruid;
	uid_t old_uid = current_uid().val;
    
    pr_info("handle_setresuid from %d to %d\n", old_uid, new_uid);

    // if old process is root, ignore it.
    if (old_uid != 0 && ksu_enhanced_security_enabled) {
        // disallow any non-ksu domain escalation from non-root to root!
        // euid is what we care about here as it controls permission
        if (unlikely(euid == 0)) {
            if (!is_ksu_domain()) {
                pr_warn("find suspicious EoP: %d %s, from %d to %d\n", 
                    current->pid, current->comm, old_uid, new_uid);
                force_sig(SIGKILL);
                return 0;
            }
        }
        // disallow appuid decrease to any other uid if it is not allowed to su
        if (is_appuid(old_uid)) {
            if (euid < current_euid().val && !ksu_is_allow_uid_for_current(old_uid)) {
                pr_warn("find suspicious EoP: %d %s, from %d to %d\n", 
                    current->pid, current->comm, old_uid, new_uid);
                force_sig(SIGKILL);
                return 0;
            }
        }
        return 0;
    }

    // if on private space, see if its possibly the manager
    if (new_uid > PER_USER_RANGE && new_uid % PER_USER_RANGE == ksu_get_manager_uid()) {
         ksu_set_manager_uid(new_uid);
    }

#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
    if (ksu_get_manager_uid() == new_uid) {
        pr_info("install fd for manager: %d\n", new_uid);
        ksu_install_fd();
        spin_lock_irq(&current->sighand->siglock);
        ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot);
        ksu_set_task_tracepoint_flag(current);
        spin_unlock_irq(&current->sighand->siglock);
        return 0;
    }

    if (ksu_is_allow_uid_for_current(new_uid)) {
        if (current->seccomp.mode == SECCOMP_MODE_FILTER &&
            current->seccomp.filter) {
            spin_lock_irq(&current->sighand->siglock);
            ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot);
            spin_unlock_irq(&current->sighand->siglock);
        }
        ksu_set_task_tracepoint_flag(current);
    } else {
        ksu_clear_task_tracepoint_flag_if_needed(current);
    }
#else
    if (ksu_is_allow_uid_for_current(new_uid)) {
		spin_lock_irq(&current->sighand->siglock);
		disable_seccomp();
		spin_unlock_irq(&current->sighand->siglock);

		if (ksu_get_manager_uid() == new_uid) {
			pr_info("install fd for ksu manager(uid=%d)\n",
				new_uid);
			ksu_install_fd();
		}

		return 0;
	}
#endif

    // Handle kernel umount
    ksu_handle_umount(old_uid, new_uid);

    return 0;
}
#else
extern bool ksu_kernel_umount_enabled;
extern bool ksu_module_mounted;
int ksu_handle_setresuid(uid_t ruid, uid_t euid, uid_t suid){
    // we rely on the fact that zygote always call setresuid(3) with same uids
    uid_t new_uid = ruid;
    uid_t old_uid = current_uid().val;

    // if old process is root, ignore it.
    if (old_uid != 0 && ksu_enhanced_security_enabled) {
        // disallow any non-ksu domain escalation from non-root to root!
        // euid is what we care about here as it controls permission
        if (unlikely(euid == 0)) {
            if (!is_ksu_domain()) {
                pr_warn("find suspicious EoP: %d %s, from %d to %d\n", 
                    current->pid, current->comm, old_uid, new_uid);
                force_sig(SIGKILL);
                return 0;
            }
        }
        // disallow appuid decrease to any other uid if it is not allowed to su
        if (is_appuid(old_uid)) {
            if (euid < current_euid().val && !ksu_is_allow_uid_for_current(old_uid)) {
                pr_warn("find suspicious EoP: %d %s, from %d to %d\n", 
                    current->pid, current->comm, old_uid, new_uid);
                force_sig(SIGKILL);
                return 0;
            }
        }
        return 0;
    }

    // We only interest in process spwaned by zygote
    if (!susfs_is_sid_equal(current_cred()->security, susfs_zygote_sid)) {
        return 0;
    }

#if __SULOG_GATE
    ksu_sulog_report_syscall(new_uid, NULL, "setuid", NULL);
#endif

    // Check if spawned process is isolated service first, and force to do umount if so  
    if (is_zygote_isolated_service_uid(new_uid) && susfs_is_umount_for_zygote_iso_service_enabled) {
        goto do_umount;
    }

    // - Since ksu maanger app uid is excluded in allow_list_arr, so ksu_uid_should_umount(manager_uid)
    //   will always return true, that's why we need to explicitly check if new_uid belongs to
    //   ksu manager
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
    if (ksu_get_manager_uid() == new_uid % 100000) {
        pr_info("install fd for manager: %d\n", new_uid);
        ksu_install_fd();
        spin_lock_irq(&current->sighand->siglock);
        ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot);
        spin_unlock_irq(&current->sighand->siglock);
        return 0;
    }
#else
    if (ksu_is_allow_uid_for_current(new_uid)) {
		spin_lock_irq(&current->sighand->siglock);
		disable_seccomp();
		spin_unlock_irq(&current->sighand->siglock);

		if (ksu_get_manager_uid() == new_uid) {
			pr_info("install fd for ksu manager(uid=%d)\n",
				new_uid);
			ksu_install_fd();
		}

		return 0;
	}
#endif

    // Check if spawned process is normal user app and needs to be umounted
    if (likely(is_zygote_normal_app_uid(new_uid) && ksu_uid_should_umount(new_uid))) {
        goto do_umount;
    }

    // Lastly, Check if spawned process is some system process and needs to be umounted
    if (unlikely(is_some_system_uid(new_uid) && susfs_is_umount_for_zygote_system_process_enabled)) {
        goto do_umount;
    }
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
    if (ksu_is_allow_uid_for_current(new_uid)) {
        if (current->seccomp.mode == SECCOMP_MODE_FILTER &&
            current->seccomp.filter) {
            spin_lock_irq(&current->sighand->siglock);
            ksu_seccomp_allow_cache(current->seccomp.filter, __NR_reboot);
            spin_unlock_irq(&current->sighand->siglock);
        }
    }
#endif

    return 0;

do_umount:
    if (!ksu_kernel_umount_enabled || !ksu_module_mounted) {
        goto skip_try_umount;
        
    }
#ifdef CONFIG_KSU_SUSFS_TRY_UMOUNT
    pr_info("susfs: running susfs_try_umount_all() for uid: %u\n", new_uid);
    susfs_try_umount_all();
#endif // #ifdef CONFIG_KSU_SUSFS_TRY_UMOUNT

skip_try_umount:

    get_task_struct(current);

#ifdef CONFIG_KSU_SUSFS_SUS_MOUNT
    // We can reorder the mnt_id now after all sus mounts are umounted
    susfs_reorder_mnt_id();
#endif // #ifdef CONFIG_KSU_SUSFS_SUS_MOUNT

    susfs_set_current_proc_umounted();

    put_task_struct(current);

#ifdef CONFIG_KSU_SUSFS_SUS_PATH
    susfs_run_sus_path_loop(new_uid);
#endif // #ifdef CONFIG_KSU_SUSFS_SUS_PATH
    return 0;
}
#endif // #ifndef CONFIG_KSU_SUSFS

void ksu_setuid_hook_init(void)
{
    ksu_kernel_umount_init();
    if (ksu_register_feature_handler(&enhanced_security_handler)) {
        pr_err("Failed to register enhanced security feature handler\n");
    }
}

void ksu_setuid_hook_exit(void)
{
    pr_info("ksu_core_exit\n");
    ksu_kernel_umount_exit();
    ksu_unregister_feature_handler(KSU_FEATURE_ENHANCED_SECURITY);
}