/*

  Copyright (c) 1996  Scott Field

  Module Name:

    nt.c

  Abstract:

    This module implements WinNT security descriptor operations for the
    Win32 Info-ZIP project.  Operation such as setting file security,
    using/querying local and remote privileges, and queuing of operations
    is performed here.  The contents of this module are only relevant
    when the code is running on Windows NT, and the target volume supports
    persistent Acl storage.

    User privileges that allow accessing certain privileged aspects of the
    security descriptor (such as the Sacl) are only used if the user specified
    to do so.

  Author:

    Scott Field (sfield@microsoft.com)

  Last revised:  18 Jan 97

 */

#define WIN32_LEAN_AND_MEAN
#define UNZIP_INTERNAL
#include "unzip.h"
#include <windows.h>
#ifdef __RSXNT__
#  include "win32/rsxntwin.h"
#endif
#include "win32/nt.h"


#ifdef NTSD_EAS         /* This file is only needed for NTSD handling */

/* Borland C++ does not define FILE_SHARE_DELETE. Others also? */
#ifndef FILE_SHARE_DELETE
#  define FILE_SHARE_DELETE 0x00000004
#endif


/* private prototypes */

static BOOL Initialize(VOID);
#if 0   /* currently unused */
static BOOL Shutdown(VOID);
#endif
static BOOL DeferSet(char *resource, PVOLUMECAPS VolumeCaps, uch *buffer);
static VOID GetRemotePrivilegesSet(CHAR *FileName, PDWORD dwRemotePrivileges);
static VOID InitLocalPrivileges(VOID);


BOOL bInitialized = FALSE;  /* module level stuff initialized? */
HANDLE hInitMutex = NULL;   /* prevent multiple initialization */

BOOL g_bRestorePrivilege = FALSE;   /* for local set file security override */
BOOL g_bSaclPrivilege = FALSE;      /* for local set sacl operations, only when
                                       restore privilege not present */

/* our single cached volume capabilities structure that describes the last
   volume root we encountered.  A single entry like this works well in the
   zip/unzip scenario for a number of reasons:
   1. typically one extraction path during unzip.
   2. typically process one volume at a time during zip, and then move
      on to the next.
   3. no cleanup code required and no memory leaks.
   4. simple code.

   This approach should be reworked to a linked list approach if we expect to
   be called by many threads which are processing a variety of input/output
   volumes, since lock contention and stale data may become a bottleneck. */

VOLUMECAPS g_VolumeCaps;
CRITICAL_SECTION VolumeCapsLock;


/* our deferred set structure linked list element, used for making a copy
   of input data which is used at a later time to process the original input
   at a time when it makes more sense. eg, applying security to newly created
   directories, after all files have been placed in such directories. */

CRITICAL_SECTION SetDeferLock;

typedef struct _DEFERRED_SET {
    struct _DEFERRED_SET *Next;
    uch *buffer;                /* must point to DWORD aligned block */
    PVOLUMECAPS VolumeCaps;
    char *resource;
} DEFERRED_SET, *PDEFERRED_SET, *LPDEFERRED_SET;

PDEFERRED_SET pSetHead = NULL;
PDEFERRED_SET pSetTail;

static BOOL Initialize(VOID)
{
    HANDLE hMutex;
    HANDLE hOldMutex;

    if(bInitialized) return TRUE;

    hMutex = CreateMutex(NULL, TRUE, NULL);
    if(hMutex == NULL) return FALSE;

    hOldMutex = (HANDLE)InterlockedExchange((LPLONG)&hInitMutex, (LONG)hMutex);

    if(hOldMutex != NULL) {
        /* somebody setup the mutex already */
        InterlockedExchange((LPLONG)&hInitMutex, (LONG)hOldMutex);

        CloseHandle(hMutex); /* close new, un-needed mutex */

        /* wait for initialization to complete and return status */
        WaitForSingleObject(hOldMutex, INFINITE);
        ReleaseMutex(hOldMutex);

        return bInitialized;
    }

    /* initialize module level resources */

    InitializeCriticalSection( &SetDeferLock );

    InitializeCriticalSection( &VolumeCapsLock );
    memset(&g_VolumeCaps, 0, sizeof(VOLUMECAPS));

    InitLocalPrivileges();

    bInitialized = TRUE;

    ReleaseMutex(hMutex); /* release correct mutex */

    return TRUE;
}

#if 0   /* currently not used ! */
static BOOL Shutdown(VOID)
{
    /* really need to free critical sections, disable enabled privilges, etc,
       but doing so brings up possibility of race conditions if those resources
       are about to be used.  The easiest way to handle this is let these
       resources be freed when the process terminates... */

    return TRUE;
}
#endif /* never */


static BOOL DeferSet(char *resource, PVOLUMECAPS VolumeCaps, uch *buffer)
{
    PDEFERRED_SET psd;
    DWORD cbDeferSet;
    DWORD cbResource;
    DWORD cbBuffer;

    if(!bInitialized) if(!Initialize()) return FALSE;

    cbResource = lstrlenA(resource) + 1;
    cbBuffer = GetSecurityDescriptorLength((PSECURITY_DESCRIPTOR)buffer);
    cbDeferSet = sizeof(DEFERRED_SET) + cbBuffer + sizeof(VOLUMECAPS) +
      cbResource;

    psd = (PDEFERRED_SET)HeapAlloc(GetProcessHeap(), 0, cbDeferSet);
    if(psd == NULL) return FALSE;

    psd->Next = NULL;
    psd->buffer = (uch *)(psd+1);
    psd->VolumeCaps = (PVOLUMECAPS)((char *)psd->buffer + cbBuffer);
    psd->resource = (char *)((char *)psd->VolumeCaps + sizeof(VOLUMECAPS));

    memcpy(psd->buffer, buffer, cbBuffer);
    memcpy(psd->VolumeCaps, VolumeCaps, sizeof(VOLUMECAPS));
    psd->VolumeCaps->bProcessDefer = TRUE;
    memcpy(psd->resource, resource, cbResource);

    /* take defer lock */
    EnterCriticalSection( &SetDeferLock );

    /* add element at tail of list */

    if(pSetHead == NULL) {
        pSetHead = psd;
    } else {
        pSetTail->Next = psd;
    }

    pSetTail = psd;

    /* release defer lock */
    LeaveCriticalSection( &SetDeferLock );

    return TRUE;
}

BOOL ProcessDefer(PDWORD dwDirectoryCount, PDWORD dwBytesProcessed,
                  PDWORD dwDirectoryFail, PDWORD dwBytesFail)
{
    PDEFERRED_SET This;
    PDEFERRED_SET Next;

    *dwDirectoryCount = 0;
    *dwBytesProcessed = 0;

    *dwDirectoryFail = 0;
    *dwBytesFail = 0;

    if(!bInitialized) return TRUE; /* nothing to do */

    EnterCriticalSection( &SetDeferLock );

    This = pSetHead;

    while(This) {

        if(SecuritySet(This->resource, This->VolumeCaps, This->buffer)) {
            (*dwDirectoryCount)++;
            *dwBytesProcessed +=
              GetSecurityDescriptorLength((PSECURITY_DESCRIPTOR)This->buffer);
        } else {
            (*dwDirectoryFail)++;
            *dwBytesFail +=
              GetSecurityDescriptorLength((PSECURITY_DESCRIPTOR)This->buffer);
        }

        Next = This->Next;
        HeapFree(GetProcessHeap(), 0, This);
        This = Next;
    }

    pSetHead = NULL;

    LeaveCriticalSection( &SetDeferLock );

    return TRUE;
}

BOOL ValidateSecurity(uch *securitydata)
{
    PSECURITY_DESCRIPTOR sd = (PSECURITY_DESCRIPTOR)securitydata;
    PACL pAcl;
    PSID pSid;
    BOOL bAclPresent;
    BOOL bDefaulted;

    if(!IsWinNT()) return TRUE; /* don't do anything if not on WinNT */

    if(!IsValidSecurityDescriptor(sd)) return FALSE;

    /* verify Dacl integrity */

    if(!GetSecurityDescriptorDacl(sd, &bAclPresent, &pAcl, &bDefaulted))
        return FALSE;

    if(bAclPresent) {
        if(!IsValidAcl(pAcl)) return FALSE;
    }

    /* verify Sacl integrity */

    if(!GetSecurityDescriptorSacl(sd, &bAclPresent, &pAcl, &bDefaulted))
        return FALSE;

    if(bAclPresent) {
        if(!IsValidAcl(pAcl)) return FALSE;
    }

    /* verify owner integrity */

    if(!GetSecurityDescriptorOwner(sd, &pSid, &bDefaulted))
        return FALSE;

    if(pSid != NULL) {
        if(!IsValidSid(pSid)) return FALSE;
    }

    /* verify group integrity */

    if(!GetSecurityDescriptorGroup(sd, &pSid, &bDefaulted))
        return FALSE;

    if(pSid != NULL) {
        if(!IsValidSid(pSid)) return FALSE;
    }

    return TRUE;
}

static VOID GetRemotePrivilegesSet(char *FileName, PDWORD dwRemotePrivileges)
{
    HANDLE hFile;

    *dwRemotePrivileges = 0;

    /* see if we have the SeRestorePrivilege */

    hFile = CreateFileA(
        FileName,
        ACCESS_SYSTEM_SECURITY | WRITE_DAC | WRITE_OWNER | READ_CONTROL,
        FILE_SHARE_READ | FILE_SHARE_DELETE, /* no sd updating allowed here */
        NULL,
        OPEN_EXISTING,
        FILE_FLAG_BACKUP_SEMANTICS,
        NULL
        );

    if(hFile != INVALID_HANDLE_VALUE) {
        /* no remote way to determine SeRestorePrivilege -- just try a
           read/write to simulate it */
        SECURITY_INFORMATION si = DACL_SECURITY_INFORMATION |
          SACL_SECURITY_INFORMATION | OWNER_SECURITY_INFORMATION |
          GROUP_SECURITY_INFORMATION;
        PSECURITY_DESCRIPTOR sd;
        DWORD cbBuf = 0;

        GetKernelObjectSecurity(hFile, si, NULL, cbBuf, &cbBuf);

        if(ERROR_INSUFFICIENT_BUFFER == GetLastError()) {
            if((sd = HeapAlloc(GetProcessHeap(), 0, cbBuf)) != NULL) {
                if(GetKernelObjectSecurity(hFile, si, sd, cbBuf, &cbBuf)) {
                    if(SetKernelObjectSecurity(hFile, si, sd))
                        *dwRemotePrivileges |= OVERRIDE_RESTORE;
                }
                HeapFree(GetProcessHeap(), 0, sd);
            }
        }

        CloseHandle(hFile);
    } else {

        /* see if we have the SeSecurityPrivilege */
        /* note we don't need this if we have SeRestorePrivilege */

        hFile = CreateFileA(
            FileName,
            ACCESS_SYSTEM_SECURITY,
            FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, /* max */
            NULL,
            OPEN_EXISTING,
            0,
            NULL
            );

        if(hFile != INVALID_HANDLE_VALUE) {
            CloseHandle(hFile);
            *dwRemotePrivileges |= OVERRIDE_SACL;
        }
    }
}


BOOL GetVolumeCaps(
    char *rootpath,         /* filepath, or NULL */
    char *name,             /* filename associated with rootpath */
    PVOLUMECAPS VolumeCaps  /* result structure describing capabilities */
    )
{
    char TempRootPath[MAX_PATH + 1];
    DWORD cchTempRootPath = 0;
    BOOL bSuccess = TRUE;   /* assume success until told otherwise */

    if(!bInitialized) if(!Initialize()) return FALSE;

    /* process the input path to produce a consistent path suitable for
       compare operations and also suitable for certain picky Win32 API
       that don't like forward slashes */

    if(rootpath != NULL && rootpath[0] != '\0') {
        DWORD i;

        cchTempRootPath = lstrlen(rootpath);
        if(cchTempRootPath > MAX_PATH) return FALSE;

        /* copy input, converting forward slashes to back slashes as we go */

        for(i = 0 ; i <= cchTempRootPath ; i++) {
            if(rootpath[i] == '/') TempRootPath[i] = '\\';
            else TempRootPath[i] = rootpath[i];
        }

        /* check for UNC and Null terminate or append trailing \ as
           appropriate */

        /* possible valid UNCs we are passed follow:
           \\machine\foo\bar (path is \\machine\foo\)
           \\machine\foo     (path is \\machine\foo\)
           \\machine\foo\
           \\.\c$\     (FIXFIX: Win32API doesn't like this - GetComputerName())
           LATERLATER: handling mounted DFS drives in the future will require
                       slightly different logic which isn't available today.
                       This is required because directories can point at
                       different servers which have differing capabilities.
         */

        if(TempRootPath[0] == '\\' && TempRootPath[1] == '\\') {
            DWORD slash = 0;

            for(i = 2 ; i < cchTempRootPath ; i++) {
                if(TempRootPath[i] == '\\') {
                    slash++;

                    if(slash == 2) {
                        i++;
                        TempRootPath[i] = '\0';
                        cchTempRootPath = i;
                        break;
                    }
                }
            }

            /* if there was only one slash found, just tack another onto the
               end */

            if(slash == 1 && TempRootPath[cchTempRootPath] != '\\') {
                TempRootPath[cchTempRootPath] = TempRootPath[0]; /* '\' */
                TempRootPath[cchTempRootPath+1] = '\0';
                cchTempRootPath++;
            }

        } else {

            if(TempRootPath[1] == ':') {

                /* drive letter specified, truncate to root */
                TempRootPath[2] = '\\';
                TempRootPath[3] = '\0';
                cchTempRootPath = 3;
            } else {

                /* must be file on current drive */
                TempRootPath[0] = '\0';
                cchTempRootPath = 0;
            }

        }

    } /* if path != NULL */

    /* grab lock protecting cached entry */
    EnterCriticalSection( &VolumeCapsLock );

    if(!g_VolumeCaps.bValid ||
       lstrcmpi(g_VolumeCaps.RootPath, TempRootPath) != 0)
    {

        /* no match found, build up new entry */

        DWORD dwFileSystemFlags;
        DWORD dwRemotePrivileges = 0;
        BOOL bRemote = FALSE;

        /* release lock during expensive operations */
        LeaveCriticalSection( &VolumeCapsLock );

        bSuccess = GetVolumeInformation(
            (TempRootPath[0] == '\0') ? NULL : TempRootPath,
            NULL, 0,
            NULL, NULL,
            &dwFileSystemFlags,
            NULL, 0);


        /* only if target volume supports Acls, and we were told to use
           privileges do we need to go out and test for the remote case */

        if(bSuccess && (dwFileSystemFlags & FS_PERSISTENT_ACLS) &&
           VolumeCaps->bUsePrivileges)
        {
            if(GetDriveType( (TempRootPath[0] == '\0') ? NULL : TempRootPath )
               == DRIVE_REMOTE)
            {
                bRemote = TRUE;

                /* make a determination about our remote capabilities */

                GetRemotePrivilegesSet(name, &dwRemotePrivileges);
            }
        }

        /* always take the lock again, since we release it below */
        EnterCriticalSection( &VolumeCapsLock );

        /* replace the existing data if successful */
        if(bSuccess) {

            lstrcpynA(g_VolumeCaps.RootPath, TempRootPath, cchTempRootPath+1);
            g_VolumeCaps.bProcessDefer = FALSE;
            g_VolumeCaps.dwFileSystemFlags = dwFileSystemFlags;
            g_VolumeCaps.bRemote = bRemote;
            g_VolumeCaps.dwRemotePrivileges = dwRemotePrivileges;
            g_VolumeCaps.bValid = TRUE;
        }
    }

    if(bSuccess) {
        /* copy input elements */
        g_VolumeCaps.bUsePrivileges = VolumeCaps->bUsePrivileges;
        g_VolumeCaps.dwFileAttributes = VolumeCaps->dwFileAttributes;

        /* give caller results */
        memcpy(VolumeCaps, &g_VolumeCaps, sizeof(VOLUMECAPS));
    } else {
        g_VolumeCaps.bValid = FALSE;
    }

    LeaveCriticalSection( &VolumeCapsLock ); /* release lock */

    return bSuccess;
}


BOOL SecuritySet(char *resource, PVOLUMECAPS VolumeCaps, uch *securitydata)
{
    HANDLE hFile;
    DWORD dwDesiredAccess = 0;
    DWORD dwFlags = 0;
    PSECURITY_DESCRIPTOR sd = (PSECURITY_DESCRIPTOR)securitydata;
    SECURITY_DESCRIPTOR_CONTROL sdc;
    SECURITY_INFORMATION RequestedInfo = 0;
    DWORD dwRev;
    BOOL bRestorePrivilege = FALSE;
    BOOL bSaclPrivilege = FALSE;
    BOOL bSuccess;

    if(!bInitialized) if(!Initialize()) return FALSE;

    /* defer directory processing */

    if(VolumeCaps->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
        if(!VolumeCaps->bProcessDefer) {
            return DeferSet(resource, VolumeCaps, securitydata);
        } else {
            /* opening a directory requires FILE_FLAG_BACKUP_SEMANTICS */
            dwFlags |= FILE_FLAG_BACKUP_SEMANTICS;
        }
    }

    /* evaluate the input security desriptor and act accordingly */

    if(!IsValidSecurityDescriptor(sd))
        return FALSE;

    if(!GetSecurityDescriptorControl(sd, &sdc, &dwRev))
        return FALSE;

    /* setup privilege usage based on if told we can use privileges, and if so,
       what privileges we have */

    if(VolumeCaps->bUsePrivileges) {
        if(VolumeCaps->bRemote) {
            /* use remotely determined privileges */
            if(VolumeCaps->dwRemotePrivileges & OVERRIDE_RESTORE)
                bRestorePrivilege = TRUE;

            if(VolumeCaps->dwRemotePrivileges & OVERRIDE_SACL)
                bSaclPrivilege = TRUE;

        } else {
            /* use local privileges */
            bRestorePrivilege = g_bRestorePrivilege;
            bSaclPrivilege = g_bSaclPrivilege;
        }
    }


    /* if a Dacl is present write Dacl out */
    /* if we have SeRestorePrivilege, write owner and group info out */

    if(sdc & SE_DACL_PRESENT) {
        dwDesiredAccess |= WRITE_DAC;
        RequestedInfo |= DACL_SECURITY_INFORMATION;

        if(bRestorePrivilege) {
            dwDesiredAccess |= WRITE_OWNER;
            RequestedInfo |= (OWNER_SECURITY_INFORMATION |
              GROUP_SECURITY_INFORMATION);
        }
    }

    /* if a Sacl is present and we have either SeRestorePrivilege or
       SeSystemSecurityPrivilege try to write Sacl out */

    if((sdc & SE_SACL_PRESENT) && (bRestorePrivilege || bSaclPrivilege)) {
        dwDesiredAccess |= ACCESS_SYSTEM_SECURITY;
        RequestedInfo |= SACL_SECURITY_INFORMATION;
    }

    if(RequestedInfo == 0)  /* nothing to do */
        return FALSE;

    if(bRestorePrivilege)
        dwFlags |= FILE_FLAG_BACKUP_SEMANTICS;

    hFile = CreateFileA(
        resource,
        dwDesiredAccess,
        FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,/* max sharing */
        NULL,
        OPEN_EXISTING,
        dwFlags,
        NULL
        );

    if(hFile == INVALID_HANDLE_VALUE)
        return FALSE;

    bSuccess = SetKernelObjectSecurity(hFile, RequestedInfo, sd);

    CloseHandle(hFile);

    return bSuccess;
}

static VOID InitLocalPrivileges(VOID)
{
    HANDLE hToken;
    TOKEN_PRIVILEGES tp;

    /* try to enable some interesting privileges that give us the ability
       to get some security information that we normally cannot.

       note that enabling privileges is only relevant on the local machine;
       when accessing files that are on a remote machine, any privileges
       that are present on the remote machine get enabled by default. */

    if(!OpenProcessToken(GetCurrentProcess(),
        TOKEN_QUERY | TOKEN_ADJUST_PRIVILEGES, &hToken))
        return;

    tp.PrivilegeCount = 1;
    tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;

    if(LookupPrivilegeValue(NULL, SE_RESTORE_NAME, &tp.Privileges[0].Luid)) {

        /* try to enable SeRestorePrivilege; if this succeeds, we can write
           all aspects of the security descriptor */

        if(AdjustTokenPrivileges(hToken, FALSE, &tp, 0, NULL, NULL) &&
           GetLastError() == ERROR_SUCCESS) g_bRestorePrivilege = TRUE;

    }

    /* try to enable SeSystemSecurityPrivilege, if SeRestorePrivilege not
       present; if this succeeds, we can write the Sacl */

    if(!g_bRestorePrivilege &&
        LookupPrivilegeValue(NULL, SE_SECURITY_NAME, &tp.Privileges[0].Luid)) {

        if(AdjustTokenPrivileges(hToken, FALSE, &tp, 0, NULL, NULL) &&
           GetLastError() == ERROR_SUCCESS) g_bSaclPrivilege = TRUE;
    }

    CloseHandle(hToken);
}
#endif /* NTSD_EAS */
