init

ass07/Makefile

@@ -0,0 +1,18 @@
+obj-m += main.o
+
+all:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
+
+test:	all
+	rmmod -f main || true
+	insmod main.ko
+	cat /sys/kernel/debug/fortytwo/foo
+	echo "bozo" > /sys/kernel/debug/fortytwo/foo
+	cat /sys/kernel/debug/fortytwo/foo
+	cat /sys/kernel/debug/fortytwo/id
+	echo -n cchauvet > /sys/kernel/debug/fortytwo/id
+	echo bozo > /sys/kernel/debug/fortytwo/id || true
+	cat /sys/kernel/debug/fortytwo/jiffies

ass07/main.c

@@ -0,0 +1,143 @@
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/rwlock_types.h>
+
+#define STUDENT_LOGIN "cchauvet"
+
+MODULE_LICENSE("GPL");
+
+struct dentry *subdir;
+
+struct dentry *id_file;
+struct dentry *jiffies_file;
+struct dentry *foo_file;
+
+static ssize_t id_read(struct file *, char *, size_t, loff_t *);
+static ssize_t id_write(struct file *, const char *, size_t, loff_t *);
+
+const struct file_operations id_file_fops = {
+	.owner = THIS_MODULE,
+	.write = id_write,
+	.read = id_read,
+};
+
+static ssize_t foo_read(struct file *, char *, size_t, loff_t *);
+static ssize_t foo_write(struct file *, const char *, size_t, loff_t *);
+
+const struct file_operations foo_file_fops = {
+	.owner = THIS_MODULE,
+	.write = foo_write,
+	.read = foo_read,
+};
+
+char foo_data[PAGE_SIZE];
+size_t foo_data_len = 0;
+DEFINE_MUTEX(foo_data_mutex);
+
+static int __init module_start(void)
+{
+	subdir = debugfs_create_dir("fortytwo", NULL);
+	if (!subdir)
+		goto create_fail;
+	
+	id_file = debugfs_create_file("id", 0666, subdir, NULL, &id_file_fops);
+	if (!id_file)
+		goto create_fail;
+	
+	debugfs_create_size_t("jiffies", 0444, subdir, (size_t *) &jiffies);
+
+	foo_file = debugfs_create_file("foo",0644, subdir, NULL, &foo_file_fops);
+	if (!foo_file)
+		goto create_fail;
+
+
+	printk(KERN_INFO "Hello world !\n");
+	return 0;
+
+create_fail:
+	debugfs_remove_recursive(subdir);
+
+	return -ENOENT;
+}
+
+static void __exit module_end(void)
+{
+	debugfs_remove_recursive(subdir);
+
+	printk(KERN_INFO "Cleaning up module.\n");
+}
+
+static ssize_t id_read(struct file *f, char *buf, size_t len, loff_t *f_pos)
+{
+	char data[] = STUDENT_LOGIN;
+	size_t data_len = strlen(data);
+
+	if(*f_pos > 0)
+		return 0;
+
+	if (copy_to_user(buf, data, data_len))
+		return -EFAULT;
+
+	*f_pos += data_len;
+	return data_len;
+}
+
+static ssize_t id_write(struct file *f, const char *buf, size_t len, loff_t *offset)
+{
+	char data[10];
+	size_t len_red = 10 > len ? len : 10;
+
+	if (copy_from_user(data, buf, len_red))
+		return -EFAULT;
+	
+	if (strcmp(data, STUDENT_LOGIN))
+		return -EINVAL;
+
+	return len_red;
+}
+
+static ssize_t foo_read(struct file *f, char __user *buf, size_t len, loff_t *offset)
+{
+	size_t len_red;
+
+	mutex_lock(&foo_data_mutex);
+
+	if (!buf)
+		return -EINVAL;
+
+	if (*offset > foo_data_len)
+		return 0;
+	
+	if (len + *offset >= foo_data_len)
+                len_red = foo_data_len - *offset;
+        else
+                len_red = len;
+	
+	if (copy_to_user(buf, foo_data + *offset, len_red))
+		return -EFAULT;
+	
+	mutex_unlock(&foo_data_mutex);
+	
+	*offset += len_red;
+	return len_red;
+}
+
+static ssize_t foo_write(struct file *, const char __user *buf, size_t len, loff_t *offset)
+{
+	if (len > PAGE_SIZE)
+		return -EINVAL;
+
+	mutex_lock(&foo_data_mutex);
+	if (copy_from_user(foo_data, buf, len))
+		return -EFAULT;
+	foo_data_len = len;
+	mutex_unlock(&foo_data_mutex);
+	*offset = len;
+	return len;
+}
+
+module_init(module_start);
+module_exit(module_end);

ass07/proof

@@ -0,0 +1,15 @@
+make -C /lib/modules/6.10.0-rc1-00027-g4a4be1ad3a6e/build M=/root/lp/ass07 modules
+make[1]: Entering directory '/usr/src/linux'
+make[1]: Leaving directory '/usr/src/linux'
+rmmod -f main || true
+insmod main.ko
+cat /sys/kernel/debug/fortytwo/foo
+echo "bozo" > /sys/kernel/debug/fortytwo/foo
+cat /sys/kernel/debug/fortytwo/foo
+bozo
+cat /sys/kernel/debug/fortytwo/id
+cchauvetecho -n cchauvet > /sys/kernel/debug/fortytwo/id
+echo bozo > /sys/kernel/debug/fortytwo/id || true
+/bin/sh: line 1: echo: write error: Invalid argument
+cat /sys/kernel/debug/fortytwo/jiffies
+4294891809