drivers/misc/tima_debug_log.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/types.h>

extern int tima_debug_modify_kernel(const char *val, struct kernel_param *kp);

#define	DEBUG_LOG_SIZE	(1<<20)
#define TIMA_DEBUG_LOGGING_START	(0xB8000000)
#define TIMA_SECURE_LOGGING_START (TIMA_DEBUG_LOGGING_START + DEBUG_LOG_SIZE)
#define	DEBUG_LOG_MAGIC	(0xaabbccdd)
#define	DEBUG_LOG_ENTRY_SIZE	128

typedef struct debug_log_entry_s {
	uint32_t	timestamp;          /* timestamp at which log entry was made*/
	uint32_t	logger_id;          /* id is 1 for tima, 2 for lkmauth app  */
#define	DEBUG_LOG_MSG_SIZE	(DEBUG_LOG_ENTRY_SIZE - sizeof(uint32_t) - sizeof(uint32_t))
	char	log_msg[DEBUG_LOG_MSG_SIZE];      /* buffer for the entry                 */
} __attribute__ ((packed)) debug_log_entry_t;

typedef struct debug_log_header_s {
	uint32_t	magic;              /* magic number                         */
	uint32_t	log_start_addr;     /* address at which log starts          */
	uint32_t	log_write_addr;     /* address at which next entry is written*/
	uint32_t	num_log_entries;    /* number of log entries                */
	char	padding[DEBUG_LOG_ENTRY_SIZE - 4 * sizeof(uint32_t)];
} __attribute__ ((packed)) debug_log_header_t;

#define DRIVER_DESC   "A kernel module to read tima debug log"

unsigned long *tima_log_addr;
unsigned long *tima_debug_log_addr;
unsigned long *tima_secure_log_addr;

/* leave the following definithion of module param call here for the compatibility with other models */
module_param_call(force_modify, tima_debug_modify_kernel, NULL, NULL, 0644);

ssize_t	tima_read(struct file *filep, char __user *buf, size_t size, loff_t *offset)
{
	/* First check is to get rid of integer overflow exploits */
	if(size > DEBUG_LOG_SIZE || (*offset) + size > DEBUG_LOG_SIZE) {
		pr_err("Extra read\n");
		return -EINVAL;
	}
	if( !strcmp(filep->f_path.dentry->d_iname, "tima_debug_log"))
		tima_log_addr = tima_debug_log_addr;
	else if( !strcmp(filep->f_path.dentry->d_iname, "tima_secure_log"))
		tima_log_addr = tima_secure_log_addr;
	else {
		pr_err("NO tima*log\n");
		return -1;
	}
	if(copy_to_user(buf, (const char *)tima_log_addr + (*offset), size)) {
		pr_err("Copy to user failed\n");
		return -1;
	} else {
		*offset += size;
		return size;
	}
}

static const struct file_operations tima_proc_fops = {
	.read		= tima_read,
};

/**
 *      tima_debug_log_read_init -  Initialization function for TIMA
 *
 *      It creates and initializes tima proc entry with initialized read handler
 */
static int __init tima_debug_log_read_init(void)
{
	if(proc_create("tima_debug_log", 0644, NULL, &tima_proc_fops) == NULL) {
		pr_err("tima_debug_log_read_init: Error creating proc entry\n");
		goto error_return;
	}
	if(proc_create("tima_secure_log", 0644, NULL, &tima_proc_fops) == NULL) {
		pr_err("tima_secure_log_read_init: Error creating proc entry\n");
		goto remove_debug_entry;
	}
	pr_info("%s: Registering /proc/tima_debug_log Interface\n", __func__);

	tima_debug_log_addr = (unsigned long *)phys_to_virt(TIMA_DEBUG_LOGGING_START);
	tima_secure_log_addr = (unsigned long *)phys_to_virt(TIMA_SECURE_LOGGING_START);

	return 0;

remove_debug_entry:
	remove_proc_entry("tima_debug_log", NULL);
error_return:
	return -1;
}

/**
 *      tima_debug_log_read_exit -  Cleanup Code for TIMA
 *
 *      It removes /proc/tima proc entry and does the required cleanup operations
 */
static void __exit tima_debug_log_read_exit(void)
{
	remove_proc_entry("tima_debug_log", NULL);
	remove_proc_entry("tima_secure_log", NULL);

	pr_info("Deregistering /proc/tima_debug_log Interface\n");
}

module_init(tima_debug_log_read_init);
module_exit(tima_debug_log_read_exit);

MODULE_DESCRIPTION(DRIVER_DESC);