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privparent.c
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privparent.c
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#include "privparent.h"
#include "privsock.h"
#include "common.h"
#include "sysutil.h"
#include "tunable.h"
static void privop_post_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 minimize_privilege() {
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");
}
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;
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;
capset(&cap_header, &cap_data);
}
void handle_parent(session_t *sess) {
minimize_privilege();
char cmd;
while (1) {
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_post_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;
}
}
}
static void privop_post_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);
addr.sin_addr.s_addr = inet_addr(ip);
int fd = tcp_client(20);
if (fd == -1) {
priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_BAD);
return;
}
if (connect_timeout(fd, &addr, tunable_connect_timeout) < 0) {
priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_BAD);
} else {
priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_OK);
priv_sock_send_fd(sess->parent_fd, fd);
}
close(fd);
}
static void privop_pasv_active(session_t *sess) {
int active;
if (sess->pasv_listen_fd != -1) {
active = 1;
} else {
active = 0;
}
priv_sock_send_int(sess->parent_fd, active);
}
static void privop_pasv_listen(session_t *sess) {
char ip[16] = {0};
getlocalip(ip);
sess->pasv_listen_fd = tcp_server(ip, 0);
struct sockaddr_in addr;
socklen_t addrlen = sizeof(addr);
if (getsockname(sess->pasv_listen_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);
}
static void privop_pasv_accept(session_t *sess) {
int fd = accept_timeout(sess->pasv_listen_fd, NULL, tunable_accept_timeout);
close(sess->pasv_listen_fd);
sess->pasv_listen_fd = -1;
if (fd == -1) {
priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_BAD);
} else {
priv_sock_send_result(sess->parent_fd, PRIV_SOCK_RESULT_OK);
priv_sock_send_fd(sess->parent_fd, fd);
close(fd);
}
}