windows-nt/Source/XPSP1/NT/shell/osshell/progman/secdesc.c

/****************************** Module Header ******************************\
* Module Name: secdesc.c
*
* Copyright (c) 1991, Microsoft Corporation
*
* Routines that support creation and deletion of security descriptors
*
* History:
* 02-06-92 Davidc       Created.
\***************************************************************************/

#include "sec.h"

//
// Private prototypes
//

PVOID
CreateAccessAllowedAce(
    PSID  Sid,
    ACCESS_MASK AccessMask,
    UCHAR AceFlags,
    UCHAR InheritFlags
    );

VOID
DestroyAce(
    PVOID   Ace
    );



/***************************************************************************\
* CreateSecurityDescriptor
*
* Creates a security descriptor containing an ACL containing the specified ACEs
*
* A SD created with this routine should be destroyed using
* DeleteSecurityDescriptor
*
* Returns a pointer to the security descriptor or NULL on failure.
*
* 02-06-92 Davidc       Created.
\***************************************************************************/

PSECURITY_DESCRIPTOR
CreateSecurityDescriptor(
    PMYACE  MyAce,
    ACEINDEX AceCount
    )
{
    NTSTATUS Status;
    ACEINDEX AceIndex;
    PACCESS_ALLOWED_ACE *Ace;
    PACL    Acl = NULL;
    PSECURITY_DESCRIPTOR SecurityDescriptor = NULL;
    DWORD   LengthAces;
    DWORD   LengthAcl;
    DWORD   LengthSd;

    //
    // Allocate space for the ACE pointer array
    //

    Ace = (PACCESS_ALLOWED_ACE *)Alloc(sizeof(PACCESS_ALLOWED_ACE) * AceCount);
    if (Ace == NULL) {
        DbgOnlyPrint("progman failed to allocated ACE array\n\r");
        return(NULL);
    }

    //
    // Create the ACEs and calculate total ACE size
    //

    LengthAces = 0;
    for (AceIndex=0; AceIndex < AceCount; AceIndex ++) {
        Ace[AceIndex] = CreateAccessAllowedAce(MyAce[AceIndex].Sid,
                                               MyAce[AceIndex].AccessMask,
                                               0,
                                               MyAce[AceIndex].InheritFlags);
        if (Ace[AceIndex] == NULL) {
            DbgOnlyPrint("progman : Failed to allocate ace\n\r");
        } else {
            LengthAces += Ace[AceIndex]->Header.AceSize;
        }
    }

    //
    // Calculate ACL and SD sizes
    //

    LengthAcl = sizeof(ACL) + LengthAces;
    LengthSd  = SECURITY_DESCRIPTOR_MIN_LENGTH;

    //
    // Create the ACL
    //

    Acl = Alloc(LengthAcl);

    if (Acl != NULL) {

        Status = RtlCreateAcl(Acl, LengthAcl, ACL_REVISION);

        if (NT_SUCCESS(Status))
        {
            //
            // Add the ACES to the ACL and destroy the ACEs
            //

            for (AceIndex = 0; AceIndex < AceCount; AceIndex ++) {

                if (Ace[AceIndex] != NULL) {

                    Status = RtlAddAce(Acl, ACL_REVISION, 0, Ace[AceIndex],
                                       Ace[AceIndex]->Header.AceSize);

                    if (!NT_SUCCESS(Status)) {
                        DbgOnlyPrint("progman : AddAce failed, status = 0x%lx\n\r", Status);
                    }

                    DestroyAce(Ace[AceIndex]);
                }
            }
        }
        else
        {
            Free(Acl);
            Acl = NULL;
        }

    } else {
        DbgOnlyPrint("progman : Failed to allocate ACL\n\r");
    }

    //
    // Free the ACE pointer array
    //
    Free(Ace);

    //
    // Create the security descriptor
    //

    SecurityDescriptor = Alloc(LengthSd);

    if (SecurityDescriptor != NULL) {

        Status = RtlCreateSecurityDescriptor(SecurityDescriptor, SECURITY_DESCRIPTOR_REVISION);
        ASSERT(NT_SUCCESS(Status));

        //
        // Set the DACL on the security descriptor
        //
        Status = RtlSetDaclSecurityDescriptor(SecurityDescriptor, TRUE, Acl, FALSE);
        if (!NT_SUCCESS(Status)) {
            DbgOnlyPrint("progman : SetDACLSD failed, status = 0x%lx\n\r", Status);
        }
    } else {
        DbgOnlyPrint("progman : Failed to allocate security descriptor\n\r");
    }

    //
    // Return with our spoils
    //
    return(SecurityDescriptor);
}


/***************************************************************************\
* DeleteSecurityDescriptor
*
* Deletes a security descriptor created using CreateSecurityDescriptor
*
* Returns TRUE on success, FALSE on failure
*
* 02-06-92 Davidc       Created.
\***************************************************************************/

BOOL
DeleteSecurityDescriptor(
    PSECURITY_DESCRIPTOR SecurityDescriptor
    )
{
    NTSTATUS Status;
    PACL    Acl;
    BOOLEAN Present;
    BOOLEAN Defaulted;

    ASSERT(SecurityDescriptor != NULL);

    //
    // Get the ACL
    //
    Status = RtlGetDaclSecurityDescriptor(SecurityDescriptor,
                                          &Present, &Acl, &Defaulted);
    if (NT_SUCCESS(Status)) {

        //
        // Destroy the ACL
        //
        if (Present && (Acl != NULL)) {
            Free(Acl);
        }
    } else {
        DbgOnlyPrint("progman : Failed to get DACL from security descriptor being destroyed, Status = 0x%lx\n\r", Status);
    }

    //
    // Destroy the Security Descriptor
    //
    Free(SecurityDescriptor);

    return(TRUE);
}


/***************************************************************************\
* CreateAccessAllowedAce
*
* Allocates memory for an ACCESS_ALLOWED_ACE and fills it in.
* The memory should be freed by calling DestroyACE.
*
* Returns pointer to ACE on success, NULL on failure
*
* History:
* 12-05-91 Davidc       Created
\***************************************************************************/
PVOID
CreateAccessAllowedAce(
    PSID  Sid,
    ACCESS_MASK AccessMask,
    UCHAR AceFlags,
    UCHAR InheritFlags
    )
{
    DWORD   LengthSid = RtlLengthSid(Sid);
    DWORD   LengthACE = sizeof(ACE_HEADER) + sizeof(ACCESS_MASK) + LengthSid;
    PACCESS_ALLOWED_ACE Ace;

    Ace = (PACCESS_ALLOWED_ACE)Alloc(LengthACE);
    if (Ace == NULL) {
        DbgOnlyPrint("progman : CreateAccessAllowedAce : Failed to allocate ace\n\r");
        return NULL;
    }

    Ace->Header.AceType = ACCESS_ALLOWED_ACE_TYPE;
    Ace->Header.AceSize = (USHORT)LengthACE;
    Ace->Header.AceFlags = AceFlags | InheritFlags;
    Ace->Mask = AccessMask;
    RtlCopySid(LengthSid, (PSID)(&(Ace->SidStart)), Sid );

    return(Ace);
}


/***************************************************************************\
* DestroyAce
*
* Frees the memory allocate for an ACE
*
* History:
* 12-05-91 Davidc       Created
\***************************************************************************/
VOID
DestroyAce(
    PVOID   Ace
    )
{
    Free(Ace);
}