learning about modules

3 files changed, 81 insertions, 8 deletions

diff --git a/src/initramfs-init.sh b/src/initramfs-init.sh
index 2144100..7ce8606 100644
--- a/src/initramfs-init.sh
+++ b/src/initramfs-init.sh
@@ -1,5 +1,9 @@
 #!/bin/sh
 
+# mount the proc file system
+mkdir /proc
+mount -t proc proc /proc
+
 insmod /usr/bin/keylogger.ko
 dmesg
 
diff --git a/src/module/module.c b/src/module/module.c
index 43edb8c..b3b92af 100644
--- a/src/module/module.c
+++ b/src/module/module.c
@@ -2,19 +2,86 @@
 #include <linux/module.h>
 #include <linux/printk.h>
 
-static int __init init(void)
+#include <linux/proc_fs.h>
+
+// #define NAME "keylogger"
+#define NAME "_test_module"
+
+ssize_t proc_read(struct file *file, char __user *user, size_t size, loff_t *off);
+ssize_t proc_write(struct file *file, const char __user *user, size_t size, loff_t *off);
+
+static struct proc_dir_entry *proc = NULL;
+static const struct proc_ops proc_fops = {
+    .proc_read  = proc_read,
+    .proc_write = proc_write,
+};
+
+static char *msg_buf = NULL;
+
+#define COPY_TO_USER(_msg, _len)                       \
+    if(copy_to_user(user, _msg, _len)) return -EFAULT; \
+    *off += _len;                                      \
+    user += _len;
+
+ssize_t proc_read(struct file *file, char __user *user, size_t size, loff_t *off)
 {
-    pr_info("Hello World!\n");
+    printk("FILE READ KEK\n");
+
+    if (*off > 0) return 0; // we have already written
+
+    if(msg_buf == NULL) {
+        COPY_TO_USER("You have no previous messages\n", 30);
+        return 30;
+    }
+
+    size_t len = strlen(msg_buf);
+    if(size < (len + 24)) return 0;
+
+    COPY_TO_USER("Your last message was: ", 23);
+    COPY_TO_USER(msg_buf, len);
+    COPY_TO_USER("\n", 1);
+
+    return len + 24;
+}
+
+ssize_t proc_write(struct file *file, const char __user *user, size_t size, loff_t *off)
+{
+    printk("FIEL WRITE KEK\n");
+
+    kfree(msg_buf);
+    if((msg_buf = kmalloc(size + 1, GFP_KERNEL)) == NULL) {
+       return -ENOMEM;
+    }
+
+    if(copy_from_user(msg_buf, user, size)) {
+        return -EFAULT;
+    }
+
+    msg_buf[size] = '\0';
+    if(msg_buf[size-1] == '\n') msg_buf[size-1] = '\0';
+
+    return size;
+}
+
+static int __init init_keylogger(void)
+{
+    printk("Init Kek\n");
+
+    if((proc = proc_create(NAME, 0666, NULL, &proc_fops)) == NULL)
+        return -ENOMEM;
     return 0;
 }
 
-static void __exit exit(void)
+static void __exit exit_keylogger(void)
 {
-    pr_info("Goodbye World!\n");
+    printk("Exit Kek\n");
+
+    proc_remove(proc);
+    kfree(msg_buf);
 }
 
-module_init(init);
-module_exit(exit);
+module_init(init_keylogger);
+module_exit(exit_keylogger);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Kartofen");
diff --git a/vm.sh b/vm.sh
index f77642f..69b9bb5 100755
--- a/vm.sh
+++ b/vm.sh
@@ -2,7 +2,7 @@
 
 function run
 {
-    qemu-system-x86_64 \
+    st qemu-system-x86_64 \
 		-kernel "$BIND/$KERNEL_NAME" \
 		-initrd "$BIND/$INITFS_NAME" \
 		-append "console=ttyS0" -nographic
@@ -12,12 +12,15 @@ function initramfs
 {
     IMG="$(pwd)/$1"
     DIR="${IMG%.*}"
+
     mkdir -p $DIR
 
     # get busybox things
     install -D $(which busybox) $DIR/bin/busybox
     ln -sf busybox $DIR/bin/sh
     ln -sf busybox $DIR/bin/dmesg
+    ln -sf busybox $DIR/bin/mount
+    # ln -sf busybox $DIR/bin/bash
 
     # copy the compiled binaries
     mkdir -p $DIR/usr/bin
@@ -29,7 +32,6 @@ function initramfs
 
     # make image and delete folder
     (cd $DIR; find . | cpio -H newc -o | gzip > $IMG)
-
     rm -rf $DIR
 }