privparent.c

#include "privparent.h"
#include "privsock.h"
#include "tunable.h"
#include "common.h"

static void privop_pasv_get_data_sock(session_t *sess);
static void privop_pasv_active(session_t *sess);
static void privop_pasv_listen(session_t *sess);
static void privop_pasv_accept(session_t *sess);

int capset(cap_user_header_t hdrp, const cap_user_data_t datap){
	return syscall(__NR_capset,hdrp,datap);
}

void get_privilege(){
		//改变权限
	struct passwd *pw = getpwnam("nobody");
	if(pw == NULL) return;
	if(setegid(pw->pw_gid) < 0) ERR_EXIT("setegid");
	if(seteuid(pw->pw_uid) < 0) ERR_EXIT("seteuid");
	//add capability
	struct __user_cap_header_struct cap_header;
	struct __user_cap_data_struct cap_data;
	memset(&cap_header, 0 ,sizeof(cap_header));
	memset(&cap_data, 0, sizeof(cap_data));
	
	cap_header.version = _LINUX_CAPABILITY_VERSION_1; //x64
	cap_header.pid = 0;

	__u32 cap_mask = 0;
	cap_mask |= (1 << CAP_NET_BIND_SERVICE);
	cap_data.effective = cap_data.permitted = cap_mask;
	cap_data.inheritable = 0;
	//end_add
	capset(&cap_header, &cap_data);
}

void handle_parent(session_t *sess){
	get_privilege();
	while(1){
		char cmd = priv_sock_get_cmd(sess->parent_fd);
		//解析内部命令

		//处理内部命令
		switch(cmd){
		case PRIV_SOCK_GET_DATA_SOCK:
			privop_pasv_get_data_sock(sess);
			break;
		case PRIV_SOCK_PASV_ACTIVE:
			privop_pasv_active(sess);
			break;
		case PRIV_SOCK_PASV_LISTEN:
			privop_pasv_listen(sess);
			break;
		case PRIV_SOCK_PASV_ACCEPT:
			privop_pasv_accept(sess);
			break;

		}
	}
}

void privop_pasv_get_data_sock(session_t *sess){
	unsigned short port = (unsigned short)priv_sock_get_int(sess->parent_fd);
	char ip[16] = {0};
	priv_sock_recv_buf(sess->parent_fd, ip, sizeof(ip));
	struct sockaddr_in addr;
	memset(&addr, 0, sizeof(addr));
	addr.sin_family = AF_INET;
	addr.sin_port = htons(port);
	inet_aton(ip, &addr.sin_addr);

	int fd = tcp_client(20);
	if(fd == -1){
		priv_sock_send_cmd(sess->parent_fd, PRIV_SOCK_RESULT_BAD);
		return;
	}
	//connect
	if(connect_timeout(fd, &addr, tunable_connect_timeout) < 0){
		priv_sock_send_cmd(sess->parent_fd, PRIV_SOCK_RESULT_BAD);
		close(fd);
		return;
	}
	printf("=====Transfer Success====\n");
	
	priv_sock_send_cmd(sess->parent_fd, PRIV_SOCK_RESULT_OK);
	priv_sock_send_fd(sess->parent_fd, fd);
	close(fd);
}
void privop_pasv_active(session_t *sess){
	int active = 0;
	if(sess->pasv_listen_fd != -1) active = 1;
	priv_sock_send_int(sess->parent_fd, active);
}
void privop_pasv_listen(session_t *sess){
	char ip[16] = {0};
	getlocalip(ip);

	int fd = tcp_server(ip, 0);
	struct sockaddr_in addr;
	socklen_t addrlen = sizeof(struct sockaddr);
	if(getsockname(fd, (struct sockaddr*)&addr, &addrlen) < 0)
		ERR_EXIT("getsockname");
	unsigned short port = ntohs(addr.sin_port);
	priv_sock_send_int(sess->parent_fd, (int)port);
	sess->pasv_listen_fd = fd;
}
void privop_pasv_accept(session_t *sess){
	int conn = accept_timeout(sess->pasv_listen_fd, NULL, tunable_accept_timeout);
	close(sess->pasv_listen_fd);
	sess->pasv_listen_fd = -1;
	if(conn < 0){
		priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_BAD);
		return;
	}
	priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_OK);
	priv_sock_send_fd(sess->parent_fd, conn);
	close(conn);
}