void *chg_uid_gid(void *arg)
{
cap_t newcaps;
cap_t mycaps;
int ret;
test_msg("Aux thread runs as UID: %d; GID: %d\n", getuid(), getgid());
newcaps = cap_from_text("cap_setgid,cap_setuid=+eip");
if (!newcaps) {
pr_perror("Failed to get capability struct\n");
exit(1);
}
ret = cap_set_proc(newcaps);
if (ret) {
pr_perror("Failed to set capabilities for the process\n");
exit(1);
}
mycaps = cap_get_proc();
if (!mycaps) {
pr_perror("Failed to get child thread capabilities\n");
exit_group(2);
}
test_msg("Child capabilities: %s\n", cap_to_text(mycaps, NULL));
test_msg("Changing UID/GID in child thread to %d:%d\n", uid, gid);
ret = syscall(SYS_setresgid, gid, gid, gid);
if (ret >= 0) {
syscall(SYS_setresuid, uid, uid, uid);
} else if (ret < 0) {
pr_perror("Failed to change UID/GID\n");
exit_group(2);
}
gid = getgid();
uid = getuid();
test_msg("Now aux thread runs as UID: %d; GID: %d\n", uid, gid);
test_msg("Child thread is waiting for main thread's signal\n");
task_waiter_complete(&t, 1);
pthread_mutex_lock(&mutex);
while (!done) {
pthread_cond_wait(&cond, &mutex);
}
pthread_mutex_unlock(&mutex);
test_msg("Child thread returns\n");
return NULL;
}
void process_igmp(struct map *group_table, uint32_t src_ip, const uint8_t *buffer, int len)
{
if( checksum(buffer, len) != 0)
return;
if(len == IGMP_HEADER_LEN){ //igmp v1, v2`
const struct igmphdr *igmp = (const struct igmphdr *) buffer;
uint32_t groupid = igmp->groupid;
switch( igmp->type ){
case QUERY_REPORT:
/*controller cannot receive query report packet*/
break;
case V1_MEMBERSHIP_REPORT:
/*same as V2_MEMBERSHIP_REPORT...*/
case V2_MEMBERSHIP_REPORT:
enter_group(group_table, groupid, src_ip);
break;
case V2_LEAVE_GROUP:
exit_group(group_table, groupid, src_ip);
break;
default:
/*error*/
break;
}
}else if(len >= IGMP_V3_REPORT_HEADER_LEN){ //igmp v3
const struct igmpv3_report *igmpv3_pkt = (const struct igmpv3_report *) buffer;
/*only deal with membership report*/
if(igmpv3_pkt->type != V3_MEMBERSHIP_REPORT)
return;
uint16_t ngrecord = ntohs(igmpv3_pkt->ngrecord);
const uint8_t *grecord = (const uint8_t *) igmpv3_pkt->grec;
int i;
/*deal with each record*/
for(i = 0; i < ngrecord; i++){
uint8_t grec_type = *grecord++;
uint8_t grec_auxdlen = *grecord++; //一般为0，不为0,则要跳过末尾的grec_auxdlen个字节
uint16_t grec_nsrc = ntohs(*((const uint16_t *)grecord));
grecord += sizeof(uint16_t);
uint32_t grec_mcaddr = ntohl(*((const uint32_t *)grecord));
grecord += sizeof(uint32_t);
switch( grec_type ){
case V3_MODE_IS_INCLUDE: //接收来自源，如果源为空则， 为退出报告，否则加入组
if( grec_nsrc == 0){ //INCLUDE{}, 表示退出报告
exit_group(group_table, grec_mcaddr, src_ip);
}else{ //不为0，表示对源进行控制，现在不对源进行控制，只进行插入
enter_group(group_table, grec_mcaddr, src_ip);
}
break;
case V3_MODE_IS_EXCLUDE:
if( grec_nsrc == 0){ //EXCLUDE{}, 表示组加入报告
enter_group(group_table, grec_mcaddr, src_ip);
}else{ //不为0，表示对源进行控制，现在不对源进行控制，只进行插入
enter_group(group_table, grec_mcaddr, src_ip);
}
break;
case V3_CHANGE_TO_INCLUDE: //源地址不为空，则当做插入，否则当做退出操作
if( grec_nsrc == 0){
exit_group(group_table, grec_mcaddr, src_ip);
}else{
enter_group(group_table, grec_mcaddr, src_ip);
}
break;
case V3_CHANGE_TO_EXCLUDE: //暂时当做插入处理
enter_group(group_table, grec_mcaddr, src_ip);
break;
case V3_ALLOW_NEW_SOURCE: //不处理
break;
case V3_BLOCK_OLD_SOURCE: //不处理
break;
default:
/*error*/
break;
}
grecord += sizeof(uint32_t) * grec_nsrc + grec_auxdlen; //step to next record
}
}else{
/*error, drop */
return;
}
return;
}
int
exit(void)
{
exit_group();
}
