path: root/src/OS/os.c-cygwin

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Cygwin-specific code. December 2002. Updated Jan 2015.
   This is prefixed to the src/os.c file.

   This code was supplied by Pierre A. Humblet <Pierre.Humblet@ieee.org>
*/

/* We need a special mkdir that
   allows names starting with // */
#undef mkdir
int cygwin_mkdir( const char *path, mode_t mode )
{
  const char * p = path;
  if (*p == '/') while(*(p+1) == '/') p++;
  return mkdir(p, mode);
}

#ifndef COMPILE_UTILITY /* Utilities don't need special code */

#ifdef INCLUDE_PAM
#include "../pam/pam.c"
#endif
#include <alloca.h>

unsigned int cygwin_WinVersion;

/* Conflict between Windows definitions and others */
#ifdef NOERROR
#undef NOERROR
#endif
#ifdef DELETE
#undef DELETE
#endif

#include <windows.h>
#include <ntstatus.h>
#include <lmcons.h>

#define EqualLuid(Luid1, Luid2) \
  ((Luid1.LowPart == Luid2.LowPart) && (Luid1.HighPart == Luid2.HighPart))
#include <sys/cygwin.h>

/* Special static variables */
static BOOL cygwin_debug = FALSE;
static int fakesetugid = 1; /* when not privileged, setugid = noop */

#undef setuid
int cygwin_setuid(uid_t uid )
{
  int res = 0;
  if (fakesetugid == 0) { 
    res = setuid(uid);
    if (cygwin_debug)
      fprintf(stderr, "setuid %u %u %d pid: %d\n",
              uid, getuid(),res, getpid());
  }
  return res;
}

#undef setgid
int cygwin_setgid(gid_t gid )
{
  int res = 0;
  if (fakesetugid == 0) { 
    res = setgid(gid);
    if (cygwin_debug)
      fprintf(stderr, "setgid %u %u %d pid: %d\n",
              gid, getgid(), res, getpid());
  }
  return res;
}

/* Background processes run at lower priority */
static void cygwin_setpriority()
{
  if (!SetPriorityClass(GetCurrentProcess(), BELOW_NORMAL_PRIORITY_CLASS))
    SetPriorityClass(GetCurrentProcess(), IDLE_PRIORITY_CLASS);
  return;
}


/* GetVersion()
   MSB: 1 for 95/98/ME; Next 7: build number, except for 95/98/ME
   Next byte: 0
   Next byte: minor version of OS
   Low  byte: major version of OS (3 or 4 for for NT, 5 for 2000 and XP) */
//#define VERSION_IS_58M(x) (x & 0x80000000) /* 95, 98, Me   */
//#define VERSION_IS_NT(x)  ((x & 0XFF) < 5) /* NT 4 or 3.51 */

/*
  Routine to find if process or thread is privileged
*/

enum {
  CREATE_BIT = 1,
};

static DWORD get_privileges ()
{
  char buffer[1024];
  DWORD i, length;
  HANDLE hToken = NULL;
  PTOKEN_PRIVILEGES privs;
  LUID cluid, rluid;
  DWORD ret = 0;

  privs = (PTOKEN_PRIVILEGES) buffer;

  if (OpenProcessToken (GetCurrentProcess(), TOKEN_QUERY, &hToken)
      && LookupPrivilegeValue (NULL, SE_CREATE_TOKEN_NAME, &cluid)
      && LookupPrivilegeValue(NULL, SE_RESTORE_NAME, &rluid)
      && (GetTokenInformation( hToken, TokenPrivileges,
                               privs, sizeof (buffer), &length)
          || (GetLastError () == ERROR_INSUFFICIENT_BUFFER
              && (privs = (PTOKEN_PRIVILEGES) alloca (length))
              && GetTokenInformation(hToken, TokenPrivileges,
                                     privs, length, &length)))) {
    for (i = 0; i < privs->PrivilegeCount; i++) {
      if (EqualLuid(privs->Privileges[i].Luid, cluid))
        ret |= CREATE_BIT;
      if (ret == (CREATE_BIT))
        break;
    }
  }
  else
    fprintf(stderr, "has_create_token_privilege %u\n", GetLastError());

  if (hToken)
    CloseHandle(hToken);

  return ret;
}

/* 
  We use cygwin_premain to fake a few things 
	and to provide some debug info 
*/
void cygwin_premain2(int argc, char ** argv, struct per_process * ptr)
{
  int i, res, is_daemon = 0, is_spoolwritable, is_privileged, is_eximuser;
  uid_t myuid, systemuid;
  gid_t mygid, adminsgid;
  struct passwd * pwp = NULL;
  struct stat buf;
  char *cygenv;
  SID(1, SystemSid, SECURITY_LOCAL_SYSTEM_RID);
  SID(2, AdminsSid, SECURITY_BUILTIN_DOMAIN_RID, DOMAIN_ALIAS_RID_ADMINS);
  DWORD priv_flags;

  myuid = getuid();
  mygid = getgid();
  cygwin_WinVersion = GetVersion();
  if ((cygenv = getenv("CYGWIN")) == NULL) cygenv = "";
  /* Produce some debugging on stderr,
     cannot yet use exim's debug functions.
     Exim does not use -c and ignores -n.
     Set lower priority for daemons */
  for (i = 1; i < argc; i++) {
    if (argv[i][0] == '-') {
      if (argv[i][1] == 'c') {
        ssize_t size;
        wchar_t *win32_path;
        argv[i][1] = 'n';  /* Replace -c by -n */
        cygwin_debug = TRUE;
        fprintf(stderr, "CYGWIN = \"%s\".\n", cygenv);
        if (((size = cygwin_conv_path(CCP_POSIX_TO_WIN_W,"/", win32_path, 0)) > 0)
 	 && ((win32_path = malloc(size)) != NULL)
         && (cygwin_conv_path(CCP_POSIX_TO_WIN_W,"/", win32_path, size) == 0)) {
	        fprintf(stderr, " Root / mapped to %ls.\n", win32_path);
		free(win32_path);
	}
      }
      else if (argv[i][1] == 'b' && argv[i][2] == 'd') {
        is_daemon = 1;
        cygwin_setpriority();
    }
  }
  }

  /* Nt/2000/XP
     We initially set the exim uid & gid to those of the "exim user",
       or to the root uid (SYSTEM) and exim gid (ADMINS),
     If privileged, we setuid to those.
     We always set the configure uid to the system uid.
     We always set the root uid to the real uid
       to allow exim imposed restrictions (bypassable by recompiling)
       and to avoid exec that cause loss of privilege
     If not privileged and unable to chown,
       we set the exim uid to our uid.
     If unprivileged and /var/spool/exim is writable and not running as listening daemon, 
       we fake all subsequent setuid. */

  /* Get the system and admins uid from their sids */
  if ((systemuid = cygwin_internal(CW_GET_UID_FROM_SID, & SystemSid)) == -1) {
	fprintf(stderr, "Cannot map System sid. Aborting\n");
	exit(1);
  }
  if ((adminsgid = cygwin_internal(CW_GET_GID_FROM_SID, & AdminsSid)) == -1) {
	fprintf(stderr, "Cannot map Admins sid. Aborting\n");
	exit(1);
  }

  priv_flags = get_privileges ();
  is_privileged = !!(priv_flags & CREATE_BIT);

  /* Call getpwnam for account exim after getting the local exim name */
  char exim_username[DNLEN + UNLEN + 2];
  if (cygwin_internal(CW_CYGNAME_FROM_WINNAME, "exim", exim_username, sizeof exim_username) != 0)
     pwp = getpwnam (exim_username);

  /* If cannot setuid to exim or and is not the daemon (which is assumed to be
     able to chown or to be the exim user) set the exim ugid to our ugid to avoid
     chown failures after creating files and to be able to setuid to exim in 
     exim.c ( "privilege not needed" ). */
  if ((is_privileged == 0) && (!is_daemon)) {
    exim_uid = myuid;
    exim_gid = mygid;
  }
  else if (pwp != NULL) {
    exim_uid = pwp->pw_uid;  /* Set it according to passwd */
    exim_gid = pwp->pw_gid;
    is_eximuser = 1;
  }
  else {
    exim_uid = systemuid;
    exim_gid = adminsgid;
    is_eximuser = 0;
  }

  res = stat("/var/spool/exim", &buf);
  /* Check if writable (and can be stat) */
  is_spoolwritable = ((res == 0) && ((buf.st_mode & S_IWOTH) != 0));

  fakesetugid = (is_privileged == 0) && (is_daemon == 0) && (is_spoolwritable == 1);

  if (is_privileged) {             /* Can setuid */
     if (cygwin_setgid(exim_gid) /* Setuid to exim */
         || cygwin_setuid(exim_uid)) {
	   fprintf(stderr, "Unable to setuid/gid to exim. priv_flags: %x\n", priv_flags);
      	   exit(0);          /* Problem... Perhaps not in 544 */
     }
  }

  /* Set the configuration file uid and gid to the system uid and admins gid. */
  config_uid = systemuid;
  config_gid = adminsgid;

  /* Pretend we are root to avoid useless exec
     and avoid exim set limitations.
     We are limited by file access rights */
  root_uid = getuid ();

  if (cygwin_debug) {
    fprintf(stderr, "Starting uid %u, gid %u, priv_flags %x, is_privileged %d, is_daemon %d, is_spoolwritable %d.\n",
            myuid, mygid, priv_flags, is_privileged, is_daemon, is_spoolwritable);
    fprintf(stderr, "root_uid %u, exim_uid %u, exim_gid %u, config_uid %u, config_gid %u, is_eximuser %d.\n",
            root_uid, exim_uid, exim_gid, config_uid, config_gid, is_eximuser);
  }
  return;
}

#ifndef OS_LOAD_AVERAGE /* Can be set on command line */
#define OS_LOAD_AVERAGE /* src/os.c need not provide it */

/*****************************************************************
 Functions for average load measurements

 Uses NtQuerySystemInformation.
 This requires definitions that are not part of
 standard include files.

 This is discouraged starting with WinXP.

*************************************************************/
/* Structure to compute the load average efficiently */
typedef struct {
  DWORD Lock;
  unsigned long long Time100ns;   /* Last measurement time */
  unsigned long long IdleCount;   /* Latest cumulative idle time */
  unsigned long long LastCounter; /* Last measurement counter */
  unsigned long long PerfFreq;    /* Perf counter frequency */
  int LastLoad;                   /* Last reported load, or -1 */
} cygwin_perf_t;

static struct {
   HANDLE handle;
   pid_t pid;
   cygwin_perf_t *perf;
} cygwin_load = {NULL, 0, NULL};

#include <ntdef.h>

typedef enum _SYSTEM_INFORMATION_CLASS
{
  SystemBasicInformation = 0,
  SystemPerformanceInformation = 2,
  SystemTimeOfDayInformation = 3,
  SystemProcessesAndThreadsInformation = 5,
  SystemProcessorTimes = 8,
  SystemPagefileInformation = 18,
  /* There are a lot more of these... */
} SYSTEM_INFORMATION_CLASS;

typedef struct _SYSTEM_BASIC_INFORMATION
{
  ULONG Unknown;
  ULONG MaximumIncrement;
  ULONG PhysicalPageSize;
  ULONG NumberOfPhysicalPages;
  ULONG LowestPhysicalPage;
  ULONG HighestPhysicalPage;
  ULONG AllocationGranularity;
  ULONG LowestUserAddress;
  ULONG HighestUserAddress;
  ULONG ActiveProcessors;
  UCHAR NumberProcessors;
} SYSTEM_BASIC_INFORMATION, *PSYSTEM_BASIC_INFORMATION;

typedef struct __attribute__ ((aligned (8))) _SYSTEM_PROCESSOR_TIMES
{
  LARGE_INTEGER IdleTime;
  LARGE_INTEGER KernelTime;
  LARGE_INTEGER UserTime;
  LARGE_INTEGER DpcTime;
  LARGE_INTEGER InterruptTime;
  ULONG InterruptCount;
} SYSTEM_PROCESSOR_TIMES, *PSYSTEM_PROCESSOR_TIMES;

typedef NTSTATUS NTAPI (*NtQuerySystemInformation_t) (SYSTEM_INFORMATION_CLASS, PVOID, ULONG, PULONG);
typedef ULONG NTAPI (*RtlNtStatusToDosError_t) (NTSTATUS);

static NtQuerySystemInformation_t NtQuerySystemInformation;
static RtlNtStatusToDosError_t RtlNtStatusToDosError;

/*****************************************************************
 *
 LoadNtdll()
 Load special functions from the NTDLL
 Return TRUE if success.

 *****************************************************************/

static BOOL LoadNtdll()
{
  HINSTANCE hinstLib;

  if ((hinstLib = LoadLibrary("NTDLL.DLL"))
      && (NtQuerySystemInformation =
          (NtQuerySystemInformation_t) GetProcAddress(hinstLib,
                                                        "NtQuerySystemInformation"))
      && (RtlNtStatusToDosError =
          (RtlNtStatusToDosError_t) GetProcAddress(hinstLib,
                                                     "RtlNtStatusToDosError")))
    return TRUE;

  DEBUG(D_load)
    debug_printf("perf: load: %u (Windows)\n", GetLastError());
  return FALSE;
}
/*****************************************************************
 *
 ReadStat()
 Measures current Time100ns and IdleCount
 Return TRUE if success.

 *****************************************************************/

static BOOL ReadStat(unsigned long long int *Time100nsPtr,
                     unsigned long long int *IdleCountPtr)
{
  NTSTATUS ret;
  SYSTEM_BASIC_INFORMATION sbi;
  PSYSTEM_PROCESSOR_TIMES spt;

  *Time100nsPtr = *IdleCountPtr = 0;

  if ((ret = NtQuerySystemInformation(SystemBasicInformation,
                                      (PVOID) &sbi, sizeof sbi, NULL))
      != STATUS_SUCCESS) {
    DEBUG(D_load)
      debug_printf("Perf: NtQuerySystemInformation: %u (Windows)\n",
                   RtlNtStatusToDosError(ret));
  }
  else if (!(spt = (PSYSTEM_PROCESSOR_TIMES) alloca(sizeof(spt[0]) * sbi.NumberProcessors))) {
    DEBUG(D_load)
      debug_printf("Perf: alloca: errno %d (%s)\n", errno, strerror(errno));
  }
  else if ((ret = NtQuerySystemInformation(SystemProcessorTimes, (PVOID) spt,
                                           sizeof spt[0] * sbi.NumberProcessors, NULL))
           != STATUS_SUCCESS) {
    DEBUG(D_load)
      debug_printf("Perf: NtQuerySystemInformation: %u (Windows)\n",
                   RtlNtStatusToDosError(ret));
  }
  else {
    int i;
    for (i = 0; i < sbi.NumberProcessors; i++) {
      *Time100nsPtr += spt[i].KernelTime.QuadPart;;
      *Time100nsPtr += spt[i].UserTime.QuadPart;
      *IdleCountPtr += spt[i].IdleTime.QuadPart;
    }
    return TRUE;
  }
  return FALSE;
}

/*****************************************************************
 *
 InitLoadAvg()
 Initialize the cygwin_load.perf structure.
 and set cygwin_load.perf->Flag to TRUE if successful.
 This is called the first time os_getloadavg is called
 *****************************************************************/
static void InitLoadAvg(cygwin_perf_t *this)
{
  BOOL success = TRUE;

  /* Get perf frequency and counter */
  QueryPerformanceFrequency((LARGE_INTEGER *)& this->PerfFreq);
  QueryPerformanceCounter((LARGE_INTEGER *)& this->LastCounter);

  /* Get initial values for Time100ns and IdleCount */
  success = success
            && ReadStat( & this->Time100ns,
                         & this->IdleCount);
  /* If success, set the Load to 0, else to -1 */
  if (success) this->LastLoad = 0;
  else {
    log_write(0, LOG_MAIN, "Cannot obtain Load Average");
    this->LastLoad = -1;
  }
}


/*****************************************************************
 *
 os_getloadavg()

 Return -1 if not available;
 Return the previous value if less than AVERAGING sec old.
 else return the processor load on a [0 - 1000] scale.

 The first time we are called we initialize the counts
 and return 0 or -1.
 The initial load cannot be measured as we use the processor 100%
*****************************************************************/
static SECURITY_ATTRIBUTES sa = {sizeof (SECURITY_ATTRIBUTES), NULL, TRUE};
#define AVERAGING 10

int os_getloadavg()
{
  unsigned long long Time100ns, IdleCount, CurrCounter;
  int value;
  pid_t newpid;

  /* New process.
     Reload the dlls and the file mapping */
  if ((newpid = getpid()) != cygwin_load.pid) {
    BOOL new;
    cygwin_load.pid = newpid;

    if (!LoadNtdll()) {
      log_write(0, LOG_MAIN, "Cannot obtain Load Average");
      cygwin_load.perf = NULL;
      return -1;
    }

    if ((new = !cygwin_load.handle)) {
      cygwin_load.handle = CreateFileMapping (INVALID_HANDLE_VALUE, &sa, PAGE_READWRITE,
                                              0, sizeof(cygwin_perf_t), NULL);
      DEBUG(D_load)
        debug_printf("Perf: CreateFileMapping: handle %p\n", (void *) cygwin_load.handle);
    }
    cygwin_load.perf = (cygwin_perf_t *) MapViewOfFile (cygwin_load.handle,
                                                        FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0);
    DEBUG(D_load)
      debug_printf("Perf: MapViewOfFile: addr %p\n", (void *) cygwin_load.perf);
    if (new && cygwin_load.perf)
      InitLoadAvg(cygwin_load.perf);
  }

  /* Check if initialized OK */
  if (!cygwin_load.perf || cygwin_load.perf->LastLoad < 0)
    return -1;

  /* If we cannot get the lock, we return 0.
     This is to prevent any lock-up possibility.
     Finding a lock busy is unlikely, and giving up only
     results in an immediate delivery .*/

  if (InterlockedCompareExchange(&cygwin_load.perf->Lock, 1, 0)) {
    DEBUG(D_load)
      debug_printf("Perf: Lock busy\n");
    return 0;
  }

    /* Get the current time (PerfCounter) */
    QueryPerformanceCounter((LARGE_INTEGER *)& CurrCounter);
    /* Calls closer than AVERAGING sec apart use the previous value */
  if (CurrCounter - cygwin_load.perf->LastCounter >
      AVERAGING * cygwin_load.perf->PerfFreq) {
      /* Get Time100ns and IdleCount */
      if (ReadStat( & Time100ns, & IdleCount)) { /* Success */
        /* Return processor load on 1000 scale */
      value = 1000 - ((1000 * (IdleCount - cygwin_load.perf->IdleCount)) /
                      (Time100ns - cygwin_load.perf->Time100ns));
      cygwin_load.perf->Time100ns = Time100ns;
      cygwin_load.perf->IdleCount = IdleCount;
      cygwin_load.perf->LastCounter = CurrCounter;
      cygwin_load.perf->LastLoad = value;
      DEBUG(D_load)
        debug_printf("Perf: New load average %d\n", value);
      }
      else { /* Something bad happened.
                Refuse to measure the load anymore
                but don't bother releasing the buffer */
        log_write(0, LOG_MAIN, "Cannot obtain Load Average");
      cygwin_load.perf->LastLoad = -1;
    }
  }
  else
  DEBUG(D_load)
      debug_printf("Perf: Old load average %d\n", cygwin_load.perf->LastLoad);
  cygwin_load.perf->Lock = 0;
  return cygwin_load.perf->LastLoad;
}
#endif /* OS_LOAD_AVERAGE */
#endif /* COMPILE_UTILITY */