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sysmonforlinux.c
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/*
SysmonForLinux
Copyright (c) Microsoft Corporation
All rights reserved.
MIT License
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ""Software""), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
//====================================================================
//
// SysmonForLinux.c
//
// Implements the main function and event handler for Sysmon For
// Linux.
//
//====================================================================
#include <libxml/parser.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <sys/types.h>
#include <linux/stat.h>
#include <fcntl.h>
#include <string.h>
#include <time.h>
#include <math.h>
#include <syslog.h>
#include <signal.h>
#include <semaphore.h>
#include <dirent.h>
#include <sys/mman.h>
#include <asm/unistd.h>
#include <dlfcn.h>
#include <libsysinternalsEBPF.h>
#include <sysinternalsEBPFshared.h>
#include "stdafx.h"
#include "rules.h"
#include "xml.h"
#include "linuxHelpers.h"
#include "sysmon_defs.h"
#include "linuxVersion.h"
#include "eula.h"
#include "networkTracker.h"
#include "installer.h"
#define EVENT_BUFFER_SIZE (49 * 1024)
#define STARTUP_SEM_NAME "/sysmon-startup"
unsigned long totalEvents = 0;
unsigned long badEvents = 0;
unsigned int numLostNotifications = 0;
unsigned long numLostEvents = 0;
PTCHAR configFile = NULL;
sem_t *startupSem = NULL;
struct NetworkTracker *NetworkState;
int eventIdFd = 0;
uint64_t *eventIdAddr = MAP_FAILED;
double g_bootSecSinceEpoch = 0;
BOOLEAN g_DebugMode = FALSE;
BOOLEAN g_DebugModeVerbose = FALSE;
CRITICAL_SECTION g_DebugModePrintCriticalSection;
typedef TCHAR _bstr_t;
bool CreateNetworkEvent( DWORD processId, DWORD threadId, EVENT_TYPE_NETWORK type, bool isTcp,
LARGE_INTEGER timestamp, ULONGLONG duration, DWORD length,
bool srcIsIpV4, const BYTE * srcAddr, WORD srcPort,
bool dstIsIpV4, const BYTE * dstAddr, WORD dstPort,
const void * const stackEntries[], DWORD stackCnt,
const _bstr_t *details );
//--------------------------------------------------------------------
//
// const EBPF Config
//
//--------------------------------------------------------------------
const char *defPaths[] =
{"./", "./sysmonEBPF", "/opt/sysmon/", "/opt/sysmon/sysmonEBPF"};
const ebpfSyscallTPprog TPenterProgs[] =
{ {EBPF_GENERIC_SYSCALL, "sysmon/generic/enterN"}
};
const ebpfSyscallTPprog TPexitProgs[] =
{ {__NR_execve, "sysmon/ProcCreate/exit"},
{__NR_execveat, "sysmon/ProcCreate/exit"},
{__NR_creat, "sysmon/FileCreate/exit"},
{__NR_open, "sysmon/FileOpen/exit"},
{__NR_openat, "sysmon/FileOpen/exit"},
{__NR_unlink, "sysmon/FileDelete/exit"},
{__NR_unlinkat, "sysmon/FileDeleteAt/exit"},
{__NR_unlinkat, "sysmon/FileDeleteAtCwd/exit"},
{__NR_accept, "sysmon/TCPaccept/exit"},
{__NR_accept4, "sysmon/TCPaccept/exit"},
{__NR_ptrace, "sysmon/ProcAccessed/exit"},
{__NR_recvfrom, "sysmon/UDPrecv/exit"},
{__NR_recvmsg, "sysmon/UDPrecv/exit"},
{__NR_recvmmsg, "sysmon/UDPrecv/exit"},
{__NR_read, "sysmon/UDPrecv/exit"},
{__NR_close, "sysmon/CloseFD/exit"}
};
const ebpfSyscallRTPprog RTPenterProgs[] =
{
{"sysmon/generic/rawEnter", EBPF_GENERIC_SYSCALL}
};
const ebpfSyscallRTPprog RTPexitProgs[] =
{
{"sysmon/ProcCreate/rawExit", __NR_execve},
{"sysmon/ProcCreate/rawExit", __NR_execveat},
{"sysmon/FileCreate/rawExit", __NR_creat},
{"sysmon/FileOpen/rawExit", __NR_open},
{"sysmon/FileOpen/rawExit", __NR_openat},
{"sysmon/FileOpen/rawExit", __NR_RAWACCESS},
{"sysmon/FileOpen/rawExit", __NR_CREATE},
{"sysmon/FileDelete/rawExit", __NR_unlink},
{"sysmon/FileDeleteAt/rawExit", __NR_unlinkat},
{"sysmon/FileDeleteAtCwd/rawExit", __NR_unlinkat},
{"sysmon/TCPaccept/rawExit", __NR_accept},
{"sysmon/TCPaccept/rawExit", __NR_accept4},
{"sysmon/TCPaccept/rawExit", __NR_NETWORK},
{"sysmon/ProcAccessed/rawExit", __NR_ptrace},
{"sysmon/UDPrecv/rawExit", __NR_recvfrom},
{"sysmon/UDPrecv/rawExit", __NR_recvmsg},
{"sysmon/UDPrecv/rawExit", __NR_recvmmsg},
{"sysmon/UDPrecv/rawExit", __NR_read},
{"sysmon/CloseFD/rawExit", __NR_close}
};
const ebpfTracepointProg otherTPprogs4_15[] =
{
{"sched", "sched_process_exit", "sysmon/sched_process_exit", __NR_PROCTERM},
{"tcp", "tcp_set_state", "sysmon/tcp_set_state", __NR_NETWORK},
{"skb", "consume_skb", "sysmon/consume_skb", __NR_NETWORK}
};
const ebpfTracepointProg otherTPprogs4_16[] =
{
{"sched", "sched_process_exit", "sysmon/sched_process_exit", __NR_PROCTERM},
{"sock", "inet_sock_set_state", "sysmon/inet_sock_set_state", __NR_NETWORK},
{"skb", "consume_skb", "sysmon/consume_skb", __NR_NETWORK}
};
const ebpfTelemetryMapObject mapObjects[] =
{
{"UDPrecvAge", 0, NULL, NULL},
{"UDPsendAge", 0, NULL, NULL}
};
// this holds the FDs for the above maps
int mapFds[sizeof(mapObjects) / sizeof(*mapObjects)];
//--------------------------------------------------------------------
//
// syslogHelper
//
// In production, this is a wrapper for syslog().
// In testing, the test harness will provide an implementation such
// that messages destined for syslog() are intercepted instead.
//
//--------------------------------------------------------------------
VOID syslogHelper( int priority, const char* fmt, const char *msg )
{
if (fmt == NULL || msg == NULL) {
fprintf(stderr, "syslogHelper invalid params\n");
return;
}
syslog( priority, fmt, msg );
}
//--------------------------------------------------------------------
//
// telemetryReady
//
// Callback from loader library to indicate that it has started up.
//
//--------------------------------------------------------------------
void telemetryReady()
{
if( OPT_SET( ConfigDefault ) ) {
SendConfigEvent( "Defaults", NULL );
} else if( configFile ) {
SendConfigEvent( configFile, NULL );
} else {
SendConfigEvent( GetCommandLine(), NULL );
}
SendStateEvent("Started", STRFILEVER);
sem_post(startupSem);
}
//--------------------------------------------------------------------
//
// isSimilarTime
//
// Compares a LARGE_INTEGER time (in 100ns increments from epoch)
// against a statx_timestamp (tv_sec and tv_nsec since epoch)
//
//--------------------------------------------------------------------
bool isSimilarTime(CONST PLARGE_INTEGER cur, CONST my_statx_timestamp *test)
{
if (cur == NULL || test == NULL) {
fprintf(stderr, "isSimilarTime invalid params\n");
return false;
}
LARGE_INTEGER testLargeTime;
LinuxFileTimeToLargeInteger(&testLargeTime, test);
if (llabs(cur->QuadPart - testLargeTime.QuadPart) < (10 * 1000 * 100)) // 100ms
return true;
return false;
}
//--------------------------------------------------------------------
//
// processFileOpen
//
// Handles file open events
//
//--------------------------------------------------------------------
void processFileOpen(CONST PSYSMON_EVENT_HEADER eventHdr)
{
if (eventHdr == NULL) {
fprintf(stderr, "processFileOpen invalid params\n");
return;
}
char newData[65536];
PSYSMON_EVENT_HEADER newEventHdr = (PSYSMON_EVENT_HEADER)newData;
newEventHdr->m_FieldFiltered = 0;
newEventHdr->m_PreFiltered = 0;
newEventHdr->m_SequenceNumber = 0;
newEventHdr->m_SessionId = 0;
PSYSMON_LINUX_FILE_OPEN event = (PSYSMON_LINUX_FILE_OPEN)&(eventHdr->m_EventBody);
if (event->m_Flags & O_CREAT &&
(event->m_Mode & S_IFMT) == S_IFREG // regular file create
) {
// file create event
newEventHdr->m_EventType = FileCreate;
PSYSMON_FILE_CREATE newEvent = &newEventHdr->m_EventBody.m_FileCreateEvent;
newEvent->m_ProcessId = event->m_ProcessId;
newEvent->m_EventTime.QuadPart = event->m_EventTime.QuadPart;
newEvent->m_CreateTime.QuadPart = event->m_EventTime.QuadPart;
newEvent->m_hashType = 0;
newEvent->m_filehash[0] = 0x00;
memset(newEvent->m_Extensions, 0, sizeof(newEvent->m_Extensions));
const char *ptr = (char *)(event + 1);
char *newPtr = (char *)(newEvent + 1);
memcpy(newPtr, ptr, event->m_Extensions[LINUX_FO_Sid]);
newEvent->m_Extensions[FC_Sid] = event->m_Extensions[LINUX_FO_Sid];
ptr += event->m_Extensions[LINUX_FO_Sid];
newPtr += event->m_Extensions[LINUX_FO_Sid];
strcpy(newPtr, ptr);
newEvent->m_Extensions[FC_ImagePath] = event->m_Extensions[LINUX_FO_ImagePath];
ptr += event->m_Extensions[LINUX_FO_ImagePath];
newPtr += event->m_Extensions[LINUX_FO_ImagePath];
strcpy(newPtr, ptr);
newEvent->m_Extensions[FC_FileName] = event->m_Extensions[LINUX_FO_PathName];
newPtr += event->m_Extensions[LINUX_FO_PathName];
newEventHdr->m_EventSize = (uint32_t)((void *)newPtr - (void *)newEventHdr);
DispatchEvent(newEventHdr);
} else if ((event->m_Mode & S_IFMT) == S_IFBLK) { // block device
newEventHdr->m_EventType = RawAccessRead;
PSYSMON_RAWACCESS_READ newEvent = &newEventHdr->m_EventBody.m_RawAccessRead;
newEvent->m_EventSystemTime.QuadPart = event->m_EventTime.QuadPart;
newEvent->m_ProcessId = event->m_ProcessId;
memset(newEvent->m_Extensions, 0, sizeof(newEvent->m_Extensions));
const char *ptr = (char *)(event + 1);
char *newPtr = (char *)(newEvent + 1);
memcpy(newPtr, ptr, event->m_Extensions[LINUX_FO_Sid]);
newEvent->m_Extensions[RR_Sid] = event->m_Extensions[LINUX_FO_Sid];
ptr += event->m_Extensions[LINUX_FO_Sid];
newPtr += event->m_Extensions[LINUX_FO_Sid];
ptr += event->m_Extensions[LINUX_FO_ImagePath];
strncpy(newEvent->m_Device, ptr, sizeof(newEvent->m_Device));
newEvent->m_Device[sizeof(newEvent->m_Device)-1] = 0;
newEventHdr->m_EventSize = (uint32_t)((void *)newPtr - (void *)newEventHdr);
DispatchEvent(newEventHdr);
}
}
//--------------------------------------------------------------------
//
// processNetworkEvent
//
// Handles file open events
//
//--------------------------------------------------------------------
void processNetworkEvent(CONST PSYSMON_EVENT_HEADER eventHdr)
{
if (eventHdr == NULL) {
fprintf(stderr, "processNetworkEvent invalid params\n");
return;
}
EVENT_TYPE_NETWORK type;
pid_t pid = 0;
BYTE sourceAddr[16];
unsigned short sourcePort;
BYTE destAddr[16];
unsigned short destPort;
bool IPv4 = true;
PSYSMON_LINUX_NETWORK_EVENT event = (PSYSMON_LINUX_NETWORK_EVENT) &eventHdr->m_EventBody;
if (event->m_IsTCP) {
if (event->m_OldState == TCP_SYN_RECV && event->m_NewState == TCP_ESTABLISHED) {
NetworkTrackerSeenFullAccept(NetworkState, event->m_AddrIsIPv4, event->m_DstAddr, event->m_DstPort,
event->m_SrcAddr, event->m_SrcPort, event->m_EventTime.QuadPart);
} else if (event->m_OldState == TCP_LISTEN && event->m_NewState == TCP_ESTABLISHED) {
if (NetworkTrackerSeenAccept(NetworkState, event->m_AddrIsIPv4, event->m_SrcAddr, event->m_SrcPort,
destAddr, &destPort)) {
pid = event->m_ProcessId;
}
} else if (event->m_OldState == TCP_SYN_RECV && event->m_NewState == TCP_CLOSE) {
NetworkTrackerCloseAccept(NetworkState, event->m_AddrIsIPv4, event->m_DstAddr, event->m_DstPort,
event->m_SrcAddr, event->m_SrcPort);
} else {
pid = NetworkTrackerSeenConnect(NetworkState, eventHdr);
memcpy(destAddr, event->m_DstAddr, 16);
destPort = event->m_DstPort;
}
if (pid != 0) {
switch (event->m_OldState) {
case TCP_SYN_SENT:
type = EVENT_TYPE_NETWORK_CONNECT;
break;
case TCP_ESTABLISHED:
type = EVENT_TYPE_NETWORK_ACCEPT;
break;
default:
type = EVENT_TYPE_NETWORK_UNKNOWN;
}
CreateNetworkEvent( pid, 0, type, true, event->m_EventTime,
0, 0,
event->m_AddrIsIPv4, event->m_SrcAddr, event->m_SrcPort,
event->m_AddrIsIPv4, destAddr, destPort,
NULL, 0, NULL );
}
} else {
int fd = (int)(long)event->m_SockId;
if (fd == 0) {
// send
type = EVENT_TYPE_NETWORK_CONNECT;
if (NetworkTrackerSeenUdpSend(NetworkState, event->m_AddrIsIPv4, event->m_SrcAddr, event->m_SrcPort,
event->m_DstAddr, event->m_DstPort, event->m_ProcessId)) {
CreateNetworkEvent( event->m_ProcessId, 0, type, false, event->m_EventTime,
0, 0,
event->m_AddrIsIPv4, event->m_SrcAddr, event->m_SrcPort,
event->m_AddrIsIPv4, event->m_DstAddr, event->m_DstPort,
NULL, 0, NULL );
}
} else {
// recv
type = EVENT_TYPE_NETWORK_ACCEPT;
if (NetworkTrackerSeenUdpRecv(NetworkState, &IPv4, destAddr, &destPort, sourceAddr, &sourcePort,
event->m_ProcessId, fd)) {
CreateNetworkEvent( event->m_ProcessId, 0, type, false, event->m_EventTime,
0, 0,
IPv4, sourceAddr, sourcePort,
IPv4, destAddr, destPort,
NULL, 0, NULL );
}
}
}
}
//--------------------------------------------------------------------
//
// getPidFromTid
//
// Gets the process ID for a thread ID
//
//--------------------------------------------------------------------
pid_t getPidFromTid(pid_t tid)
{
DIR *d, *d2;
struct dirent *dir, *dir2;
struct stat stStat;
char pidfilepath[PATH_MAX];
char taskfilepath[PATH_MAX];
pid_t pid;
snprintf(pidfilepath, sizeof(pidfilepath), "/proc/%d", tid);
//
// if /proc/TID exists, then the PID == TID
//
if (stat(pidfilepath, &stStat) == 0) {
return tid;
}
d = opendir("/proc");
if (d) {
while ((dir = readdir(d)) != NULL) {
if (!StrIsNum(dir->d_name))
continue;
pid = atoi(dir->d_name);
snprintf(taskfilepath, sizeof(taskfilepath), "/proc/%d/task", pid);
d2 = opendir(taskfilepath);
if (d2) {
while ((dir2 = readdir(d2)) != NULL) {
if (!StrIsNum(dir2->d_name))
continue;
if (atoi(dir2->d_name) == tid) {
closedir(d2);
closedir(d);
return pid;
}
}
closedir(d2);
}
}
closedir(d);
}
return -1;
}
//--------------------------------------------------------------------
//
// processProcessAccess
//
// Handles process access events
//
//--------------------------------------------------------------------
void processProcessAccess(CONST PSYSMON_EVENT_HEADER eventHdr)
{
if (eventHdr == NULL) {
fprintf(stderr, "processProcessAccess invalid params\n");
return;
}
char newData[65536];
pid_t pid;
char exePath[PATH_MAX];
ssize_t linkSize = 0;
const char *ptr = NULL;
char *newPtr = NULL;
PSYSMON_PROCESS_ACCESS event = &eventHdr->m_EventBody.m_ProcessAccessEvent;
PSYSMON_EVENT_HEADER newEventHdr = (PSYSMON_EVENT_HEADER)newData;
PSYSMON_PROCESS_ACCESS newEvent = NULL;
struct stat st;
char pathFile[32];
pid = getPidFromTid(event->m_TargetPid);
//
// if we cannot identify the PID from the target TID, just dispatch as is
//
if (pid < 0) {
DispatchEvent(eventHdr);
return;
}
//
// attempt to fill-in the target TID's image path, from the discovered PID;
// we cannot edit the existing event so we make a copy to modify.
// Extensions are variable length and follow the event body, so use the
// largest buffer possible temporarily.
//
memcpy(newData, eventHdr, eventHdr->m_EventSize);
newEvent = &newEventHdr->m_EventBody.m_ProcessAccessEvent;
ptr = (char *)(event + 1);
newPtr = (char *)(newEvent + 1);
//
// move pointer beyond existing client image path
//
ptr += event->m_Extensions[PA_ClientImage];
newPtr += newEvent->m_Extensions[PA_ClientImage];
//
// retrive path pointed to by process' exe link
//
snprintf(exePath, sizeof(exePath), "/proc/%d/exe", pid);
linkSize = readlink(exePath, newPtr, PATH_MAX);
//
// check for success
//
if (linkSize >= 0) {
//
// null-terminate path and store length in extensions array
//
newPtr[linkSize] = 0x00;
newEvent->m_Extensions[PA_TargetImage] = linkSize + 1;
newPtr += newEvent->m_Extensions[PA_TargetImage];
}
//
// copy in SidSource
//
*(uint64_t *)newPtr = *(uint64_t *)ptr & 0xFFFFFFFF;
newEvent->m_Extensions[PA_SidSource] = sizeof(uint64_t);
newPtr += newEvent->m_Extensions[PA_SidSource];
//
// retrieve SidTarget
//
snprintf(pathFile, 32, "/proc/%d", pid);
if (stat(pathFile, &st) == 0) {
*(uint64_t *)newPtr = st.st_uid;
newEvent->m_Extensions[PA_SidTarget] = sizeof(uint64_t);
newPtr += sizeof(uint64_t);
}
//
// calculate new event size and dispath
//
newEventHdr->m_EventSize = (uint32_t)((void *)newPtr - (void *)newEventHdr);
DispatchEvent(newEventHdr);
}
//--------------------------------------------------------------------
//
// handleEvent
//
// Receives the eBPF telemetry and sends it to DispatchEvent().
//
//--------------------------------------------------------------------
static void handleEvent(void *ctx, int cpu, void *data, uint32_t size)
{
if (size < 16 || data == NULL) {
printf("BAD EVENT: size=%d\n", size);
badEvents++;
return;
}
PSYSMON_EVENT_HEADER eventHdr = (PSYSMON_EVENT_HEADER)data;
totalEvents++;
switch ((DWORD)eventHdr->m_EventType) {
case LinuxFileOpen:
processFileOpen(eventHdr);
break;
case LinuxNetworkEvent:
processNetworkEvent(eventHdr);
break;
case ProcessAccess:
processProcessAccess(eventHdr);
break;
case ProcessTerminate:
{
PSYSMON_PROCESS_TERMINATE event = (PSYSMON_PROCESS_TERMINATE)&eventHdr->m_EventBody.m_ProcessTerminateEvent;
NetworkTrackerUdpProgramTermination(NetworkState, event->m_ProcessId);
DispatchEvent(eventHdr);
break;
}
default:
DispatchEvent(eventHdr);
}
}
//--------------------------------------------------------------------
//
// handleLostEvents
//
// If the userland cannot keep up with the perf ring buffer, then
// this callback will be called to indicate that events were lost.
//
//--------------------------------------------------------------------
void handleLostEvents(void *ctx, int cpu, uint64_t lostCnt)
{
fprintf(stdout, "Lost %lu events on CPU #%d!\n", lostCnt, cpu);
numLostNotifications++;
numLostEvents += lostCnt;
}
//--------------------------------------------------------------------
//
// intHandler
//
// Called on CTRL-C. Tidies up and prints out some stats.
//
//--------------------------------------------------------------------
void intHandler(int code)
{
printf("\nStopping....\n");
telemetryCloseAll();
SendStateEvent("Stopped", STRFILEVER);
if (eventIdAddr != NULL && eventIdAddr != MAP_FAILED) {
munmap(eventIdAddr, sizeof(uint64_t));
}
if (eventIdFd > 0) {
close(eventIdFd);
}
printf("Total events: %ld, bad events: %ld, ratio = %f\n", totalEvents, badEvents, (double)badEvents / totalEvents);
printf("Lost events: %ld, in %d notifications\n", numLostEvents, numLostNotifications);
exit(0);
}
//--------------------------------------------------------------------
//
// PrintBanner
//
// Print program banner.
//
//--------------------------------------------------------------------
void
PrintBanner(
const int* argc,
const char *argv[]
)
{
printf("\n");
printf("Sysmon v%s - Monitors system events\n", STRFILEVER);
printf("%s\n", VER_COMPANY);
printf("%s\n", VER_COPYRIGHT);
printf("\n");
}
//--------------------------------------------------------------------
//
// CheckRootPrivs
//
// Check if we are running as root and exit if not.
// In the future we might vary this to check for the privileges
// required to run eBPF instead.
//
//--------------------------------------------------------------------
void
CheckRootPrivs()
{
if (geteuid() != 0) {
printf("You need to run Sysmon as root.\n\n");
exit(ERROR_ELEVATION_REQUIRED);
}
}
//--------------------------------------------------------------------
//
// AcceptEula
//
// Record acceptance of the EULA by creating the file
// /opt/sysmon/eula_accepted
//
//--------------------------------------------------------------------
void
AcceptEula()
{
struct stat dir;
FILE* fp = NULL;
if (stat(SYSMON_INSTALL_DIR, &dir)) {
mkdir(SYSMON_INSTALL_DIR, S_IRWXU);
}
fp = fopen(SYSMON_EULA_FILE, "w");
if (fp != NULL) {
fclose(fp);
}
}
//--------------------------------------------------------------------
//
// EulaAccepted
//
// Check if the EULA has already been accepted by checking for the
// existance of the file /opt/sysmon/eula_accepted
//
//--------------------------------------------------------------------
BOOL
EulaAccepted()
{
struct stat eula_stat;
if (stat(SYSMON_EULA_FILE, &eula_stat) == 0) {
return TRUE;
} else {
return FALSE;
}
}
//--------------------------------------------------------------------
//
// ShowEula
//
// Display the EULA text.
//
//--------------------------------------------------------------------
void
ShowEula()
{
printf("%s\n\n", RawEulaText);
printf("This is the first run of this program. You must accept EULA to run Sysmon.\n");
printf("Use -accepteula to accept EULA.\n\n");
}
//--------------------------------------------------------------------
//
// WriteRulesBlob
//
// Write the rules to a binary file in the install dir for later
// display.
// Note, size==0 (and therefore data possibly == NULL) is valid,
// resulting in an empty file.
//
//--------------------------------------------------------------------
bool WriteRulesBlob(PVOID data, ULONG size)
{
int fd;
size_t written = 0;
ssize_t writeRet = 0;
unlink(SYSMON_RULES_FILE);
fd = creat(SYSMON_RULES_FILE, S_IRUSR | S_IWUSR);
if (fd < 0)
return false;
while (written < size) {
writeRet = write(fd, data + written, size - written);
if (writeRet < 0) {
close(fd);
unlink(SYSMON_RULES_FILE);
return false;
}
written += writeRet;
}
close(fd);
return true;
}
//--------------------------------------------------------------------
//
// SetSyscallActive
//
// Sets the appropriate syscall for the given event ID
//
//--------------------------------------------------------------------
void SetSyscallActive(bool *s, ULONG eventId)
{
switch(eventId) {
case SYSMONEVENT_CREATE_PROCESS_EVENT_value:
s[__NR_execve] = true;
s[__NR_execveat] = true;
break;
case SYSMONEVENT_NETWORK_CONNECT_EVENT_value:
s[__NR_accept] = true;
s[__NR_accept4] = true;
s[__NR_recvfrom] = true;
s[__NR_recvmsg] = true;
s[__NR_recvmmsg] = true;
s[__NR_read] = true;
s[__NR_NETWORK] = true;
break;
case SYSMONEVENT_PROCESS_TERMINATE_EVENT_value:
s[__NR_PROCTERM] = true;
break;
case SYSMONEVENT_RAWACCESS_READ_EVENT_value:
s[__NR_open] = true;
s[__NR_openat] = true;
s[__NR_RAWACCESS] = true;
break;
case SYSMONEVENT_FILE_CREATE_EVENT_value:
s[__NR_open] = true;
s[__NR_openat] = true;
s[__NR_creat] = true;
s[__NR_CREATE] = true;
break;
case SYSMONEVENT_FILE_DELETE_EVENT_value:
s[__NR_unlink] = true;
s[__NR_unlinkat] = true;
break;
case SYSMONEVENT_ACCESS_PROCESS_EVENT_value:
s[__NR_ptrace] = true;
break;
default:
break;
}
}
//--------------------------------------------------------------------
//
// SetActiveSyscalls
//
// Analyse the rules and enable appropriate syscalls
//
//--------------------------------------------------------------------
void SetActiveSyscalls(bool *s)
{
if (s == NULL) {
fprintf(stderr, "SetActiveSyscalls invalid params\n");
return;
}
RULE_CONTEXT ruleContext;
RULE_REG_EXT ruleRegExt;
PRULE_EVENT ruleEvent = NULL;
ULONG index = 0;
memset( &ruleContext, 0, sizeof( ruleContext ) );
memset( &ruleRegExt, 0, sizeof( ruleRegExt ) );
//
// Set the default rules as active
//
for( index = 0; index < AllEventsCount; index++ ) {
if( AllEvents[index]->RuleName == NULL )
continue;
if( AllEvents[index]->Default == Rule_include ) {
SetSyscallActive( s, AllEvents[index]->EventId );
}
}
//
// Get the rules
//
if( !InitializeRuleContext( &ruleContext ) )
{
//
// No rules
//
return;
}
if( GetRuleRegExtInformation( &ruleContext, &ruleRegExt ) &&
ruleRegExt.header.RuleCount > 0 )
{
//
// Set the rules active
//
for( ruleEvent = NextRuleEvent( &ruleContext, NULL );
ruleEvent != NULL;
ruleEvent = NextRuleEvent( &ruleContext, ruleEvent ) ) {
SetSyscallActive( s, ruleEvent->EventId );
}
}
ReleaseRuleContext( &ruleContext );
}
//--------------------------------------------------------------------
//
// setConfigFromStoredArgv
//
// Retrieve the command line from the install directory and use it to
// configure Sysmon
//
//--------------------------------------------------------------------
bool setConfigFromStoredArgv(
PTCHAR *configFile,
bool *activeSyscalls
)
{
if( configFile == NULL || activeSyscalls == NULL ) {
fprintf( stderr, "setConfigFromStoredArgv invalid params\n" );
return false;
}
int argc = 0;
static char **argv = NULL;
PVOID rules = NULL;
ULONG rulesSize = 0;
TCHAR configHash[256] = { 0 };
SIZE_T z;
PTCHAR parsedConfigFile = NULL;
//
// argv persists as its pointers are assigned to the config by
// ParseCommandLine; so if it is already allocated, free the previous one.
//
if( argv != NULL ) {
free( argv );
}
//
// Read argc and argv from sysmon install directory
// note: this mallocs argv
//
if( !readArgv( &argc, &argv, configFile ) ) {
fprintf( stderr, "Could not read argv and argc\n" );
exit( 1 );
}
//
// Unset previous command line arguments
//
for( z = 0; z < ConfigOptionTypeCount; z++ ) {
ConfigOptionType[z].Option->IsSet = false;
ConfigOptionType[z].Option->Value = NULL;
ConfigOptionType[z].Option->Size = 0;
}
//
// Parse the command line using the data from manifest.xml
//
if( !ParseCommandLine( argc, argv, &rules, &rulesSize,
&parsedConfigFile, configHash, _countof( configHash ) ) ) {
fprintf( stderr, "Could not parse new rules\n" );
free( argv );
//
// argv is static to preserve used memory
//
argv = NULL;
return false;
}
//
// Initialize and load any user-specified max field sizes
//
if( !LoadVariableFieldSizes( OPT_VALUE( FieldSizes ) ) ) {
fprintf( stderr, "Could not load variable field sizes\n" );
free( argv );
//
// argv is static to preserve used memory
//
argv = NULL;
return false;
}
//
// Store any user-specified max field sizes
//
if( !writeFieldSizes( OPT_VALUE( FieldSizes ) ) ) {
fprintf( stderr, "Could not write max field sizes\n" );
free( argv );
//
// argv is static to preserve used memory
//
argv = NULL;
return false;
}
//
// Write rules blob to file
//
WriteRulesBlob( rules, rulesSize );
//
// Set active rules
//
SetActiveSyscalls( activeSyscalls );
return true;
}
//--------------------------------------------------------------------
//
// configChange
//
// Called when config has changed.
//
//--------------------------------------------------------------------
void configChange()
{
bool activeSyscalls[SYSCALL_ARRAY_SIZE];
memset( activeSyscalls, 0, sizeof( activeSyscalls ) );
//
// Load the command line from the stored argv
//
if ( !setConfigFromStoredArgv( &configFile, activeSyscalls ) )
return;
//
// Update the EBPF programs
//
telemetryUpdateSyscalls( activeSyscalls );
//
// Send config change event
//
SendConfigEvent( configFile, NULL );