laffun.c

/*
    LAF - Linux Application Firewall  (for linux Intel 32 and 64bits and ARM 32 bits)
	laffun (user space LAF common functions)

    Copyright 2015-2016 by @sha0coder and @capi_x 

    Licensed under GNU General Public License 3.0 or later.
    Some rights reserved. See COPYING, AUTHORS.

    @license GPL-3.0 <http://www.gnu.org/licenses/gpl-3.0.txt>
*/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/sysctl.h>
#include <linux/netlink.h>

#include "laf.h"
#include "laffun.h"

int open_netlink(void)
{
	int sock;
	struct sockaddr_nl addr;
	int group = NETLINK_LAF_GRP;

	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_LAF_USR);
	if (sock < 0) {
		fprintf(stderr, "error: can't open socket.\n");
		return -1;
	}

	memset((void *) &addr, 0, sizeof(addr));
	addr.nl_family = AF_NETLINK;
	addr.nl_pid = getpid();

	if (bind(sock, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
		printf("bind < 0.\n");
		return -1;
	}

	if (setsockopt(sock, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group)) < 0) {
		fprintf(stderr, "error: can't open netlink.\n");
		close(sock);
	   	return -1;
   	}

	return sock;
}

void send_event(int sock, char *buffer)
{
	struct sockaddr_nl nladdr;
	struct msghdr msg;
	struct iovec iov;
	struct nlmsghdr *nlh = NULL;
	int buflen = NLMSG_SPACE(strlen(buffer) + 1);

	memset(&msg,    0, sizeof(msg));
	memset(&nlh,    0, sizeof(nlh));
	memset(&nladdr, 0, sizeof(nladdr));
	memset(&nladdr, 0, sizeof(nladdr));

	nladdr.nl_family = AF_NETLINK;
	nladdr.nl_pid    = 0;	/* 0 = send to Linux kernel */
	nladdr.nl_groups = 0;	/* 0 = unicast */

	nlh = (struct nlmsghdr *)malloc(buflen);

	nlh->nlmsg_len = NLMSG_SPACE(buflen);
	nlh->nlmsg_pid = getpid();
	nlh->nlmsg_flags = 0;

	strcpy(NLMSG_DATA(nlh), buffer);

	iov.iov_base = (void *)nlh;
	iov.iov_len  = nlh->nlmsg_len;
	msg.msg_name = (void *) &(nladdr);
	msg.msg_namelen = sizeof(nladdr);
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;

	if (DEBUG)
		printf("sending...\n");

	sendmsg(sock, &msg, 0);

	return;
}

void read_event(int sock, int wait)
{
	struct sockaddr_nl nladdr;
	struct msghdr msg;
	struct iovec iov;
	char buffer[MAX_WL_NUMB];
	int  ret;

	iov.iov_base = (void *) buffer;
	iov.iov_len  = sizeof(buffer);
	msg.msg_name = (void *) &(nladdr);
	msg.msg_namelen = sizeof(nladdr);
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;

	if (DEBUG)
		printf("listening...\n");

	ret = recvmsg(sock, &msg, wait);
	if (ret < 0)
		fprintf(stderr, "error: can't recv data.\n");
	else
		printf("%s\n", (char *) NLMSG_DATA((struct nlmsghdr *) &buffer));
}

void read_event_buf(int sock, int wait, char *buf_in, size_t buf_in_len)
{
	struct sockaddr_nl nladdr;
	struct msghdr msg;
	struct iovec iov;
	char buffer[MAX_WL_NUMB];
	int  ret;

	iov.iov_base = (void *) buffer;
	iov.iov_len  = sizeof(buffer);
	msg.msg_name = (void *) &(nladdr);
	msg.msg_namelen = sizeof(nladdr);
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;

	if (DEBUG)
		printf("listening...\n");

	ret = recvmsg(sock, &msg, wait);
	if (ret < 0)
		fprintf(stderr, "error: can't recv data.\n");
	else
		strncpy(buf_in,NLMSG_DATA((struct nlmsghdr *) &buffer),buf_in_len - 1);
}

int read_config (char *path, char *whitelist_exact, char *whitelist_similar) {
	FILE   *fp;
	char   *line = NULL;
	size_t  len = 0;
	ssize_t read;
	char    flag_exact   = 0;
	char    flag_similar = 0;
	int     wl_size_e    = 0;
	int     wl_size_s    = 0;

	fp = fopen(path, "r");
	if (fp == NULL) {
		fprintf(stderr, "error: can't read the file %s\n", path);
		return -1;
	}

	while ((read = getline(&line, &len, fp)) != -1) {
		if (line[0] == ' ' || line[0] == ';' || line[0] == '\n')
			continue;

		if (line[0] == '[') {
			line[read - 2] = '\0';
			line++;

			if (strcmp(line,"whitelist_exact") == 0) {
				flag_exact   = 1;
				flag_similar = 0;
			}

			if (strcmp(line,"whitelist_similar") == 0) {
				flag_exact   = 0;
				flag_similar = 1;
			}

			continue;
		}

		line[read - 1] = '/';

		if (wl_size_e + read >= MAX_WL_NUMB - 1 || wl_size_e + read >= MAX_WL_NUMB - 1) {
			fprintf(stderr, "error: the section in the config file is more than %i bytes.\n", MAX_WL_NUMB);
			fclose(fp);
			return -1;
		}

		if (flag_exact) {
			wl_size_e += read;
			strcat(whitelist_exact,line);
		}

		if (flag_similar) {
			wl_size_s += read;
			strcat(whitelist_similar,line);
		}
	}

	fclose(fp);

	return 0;
}

int laf_set_sysctl(int status) {
	FILE *sys_enable_fp;
	sys_enable_fp = fopen("/proc/sys/kernel/laf/enabled", "w");

	if (sys_enable_fp) {
		fprintf(sys_enable_fp, "%i\n%c", status, '\0');
		fclose (sys_enable_fp);
	} else
		return -1;

	return 0;
}


int laf_add_whitelist(int wl_type, char *path, char *cmd) {
	FILE   *fp_r, *fp_w;
	char   *line = NULL;
	char   *buffer;
	size_t  len = 0;
	ssize_t read;
	char    flag_search = 0;
	int		f_size = 0;
	int		f_seek = 0;
	int		cmd_len = 0, i = 0, ret = 0;

	if (wl_type > 1)
		return -1;

	fp_r = fopen(path, "r+");
	if (fp_r == NULL) {
		fprintf(stderr, "error: can't read the file %s\n", path);
		return -1;
	}

	cmd_len = strlen(cmd);

	while ((read = getline(&line, &len, fp_r)) != -1) {

		if (cmd_len == (read -1) && (strncmp(line,cmd,read -1) == 0)) {
			fclose(fp_r);
			return 1;
		}

		if ((strcmp(line,"[whitelist_exact]\n")   == 0 && wl_type == 0) || 
			(strcmp(line,"[whitelist_similar]\n") == 0 && wl_type == 1)) {
			f_seek = ftell(fp_r);
		}

	}

	fseek(fp_r, 0, SEEK_END);
	f_size = ftell(fp_r);
	fseek(fp_r, 0, SEEK_SET);

	buffer = malloc((f_size + 1) * sizeof(char));
	ret = fread(buffer, f_size, 1, fp_r);

	fclose(fp_r);

	fp_w = fopen(path, "w+");
	for (i=0; i < f_seek; i++)
		fputc(buffer[i],fp_w);

	fprintf(fp_w,"%s\n",cmd);

	for (i=f_seek; i < f_size; i++)
		fputc(buffer[i],fp_w);

	fclose(fp_w);

	free(buffer);

	return 0;
}