policy.c

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                  PPPP    OOO   L      IIIII   CCCC  Y   Y                   %
%                  P   P  O   O  L        I    C       Y Y                    %
%                  PPPP   O   O  L        I    C        Y                     %
%                  P      O   O  L        I    C        Y                     %
%                  P       OOO   LLLLL  IIIII   CCCC    Y                     %
%                                                                             %
%                                                                             %
%                         MagickCore Policy Methods                           %
%                                                                             %
%                              Software Design                                %
%                                   Cristy                                    %
%                                 July 1992                                   %
%                                                                             %
%                                                                             %
%  Copyright @ 1999 ImageMagick Studio LLC, a non-profit organization         %
%  dedicated to making software imaging solutions freely available.           %
%                                                                             %
%  You may not use this file except in compliance with the License.  You may  %
%  obtain a copy of the License at                                            %
%                                                                             %
%    https://imagemagick.org/license/                                         %
%                                                                             %
%  Unless required by applicable law or agreed to in writing, software        %
%  distributed under the License is distributed on an "AS IS" BASIS,          %
%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
%  See the License for the specific language governing permissions and        %
%  limitations under the License.                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
*/
␌
/*
  Include declarations.
*/
#include "MagickCore/studio.h"
#include "MagickCore/cache-private.h"
#include "MagickCore/client.h"
#include "MagickCore/configure.h"
#include "MagickCore/configure-private.h"
#include "MagickCore/exception.h"
#include "MagickCore/exception-private.h"
#include "MagickCore/linked-list-private.h"
#include "MagickCore/magick-private.h"
#include "MagickCore/memory_.h"
#include "MagickCore/memory-private.h"
#include "MagickCore/monitor.h"
#include "MagickCore/monitor-private.h"
#include "MagickCore/option.h"
#include "MagickCore/policy.h"
#include "MagickCore/policy-private.h"
#include "MagickCore/resource_.h"
#include "MagickCore/resource-private.h"
#include "MagickCore/semaphore.h"
#include "MagickCore/stream-private.h"
#include "MagickCore/string_.h"
#include "MagickCore/string-private.h"
#include "MagickCore/token.h"
#include "MagickCore/timer-private.h"
#include "MagickCore/utility.h"
#include "MagickCore/utility-private.h"
#include "MagickCore/xml-tree.h"
#include "MagickCore/xml-tree-private.h"
#if defined(MAGICKCORE_XML_DELEGATE)
#  include <libxml/parser.h>
#  include <libxml/tree.h>
#endif
␌
/*
  Define declarations.
*/
#define PolicyFilename  "policy.xml"
␌
/*
  Typedef declarations.
*/
struct _PolicyInfo
{
  char
    *path;
 
  PolicyDomain
    domain;
 
  PolicyRights
    rights;
 
  char
    *name,
    *pattern,
    *value;
 
  MagickBooleanType
    exempt,
    stealth,
    debug;
 
  SemaphoreInfo
    *semaphore;
 
  size_t
    signature;
};
 
typedef struct _PolicyMapInfo
{
  const PolicyDomain
    domain;
 
  const PolicyRights
    rights;
 
  const char
    *name,
    *pattern,
    *value;
} PolicyMapInfo;
␌
/*
  Static declarations.
*/
static const PolicyMapInfo
  PolicyMap[] =
  {
    { UndefinedPolicyDomain, UndefinedPolicyRights, (const char *) NULL,
      (const char *) NULL, (const char *) NULL }
  };
 
static LinkedListInfo
  *policy_cache = (LinkedListInfo *) NULL;
 
static SemaphoreInfo
  *policy_semaphore = (SemaphoreInfo *) NULL;
␌
/*
  Forward declarations.
*/
static MagickBooleanType
  IsPolicyCacheInstantiated(ExceptionInfo *),
  LoadPolicyCache(LinkedListInfo *,const char *,const char *,const size_t,
    ExceptionInfo *);
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%  A c q u i r e P o l i c y C a c h e                                        %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  AcquirePolicyCache() caches one or more policy configurations which provides
%  a mapping between policy attributes and a policy name.
%
%  The format of the AcquirePolicyCache method is:
%
%      LinkedListInfo *AcquirePolicyCache(const char *filename,
%        ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o filename: the policy configuration file name.
%
%    o exception: return any errors or warnings in this structure.
%
*/
static LinkedListInfo *AcquirePolicyCache(const char *filename,
  ExceptionInfo *exception)
{
  LinkedListInfo
    *cache;
 
  MagickBooleanType
    status;
 
  ssize_t
    i;
 
  /*
    Load external policy map.
  */
  cache=NewLinkedList(0);
  status=MagickTrue;
#if MAGICKCORE_ZERO_CONFIGURATION_SUPPORT
  magick_unreferenced(filename);
  status=LoadPolicyCache(cache,ZeroConfigurationPolicy,"[zero-configuration]",0,
    exception);
  if (status == MagickFalse)
    CatchException(exception);
#else
  {
    const StringInfo
      *option;
 
    LinkedListInfo
      *options;
 
    options=GetConfigureOptions(filename,exception);
    option=(const StringInfo *) GetNextValueInLinkedList(options);
    while (option != (const StringInfo *) NULL)
    {
      status=LoadPolicyCache(cache,(const char *) GetStringInfoDatum(option),
        GetStringInfoPath(option),0,exception);
      if (status == MagickFalse)
        CatchException(exception);
      option=(const StringInfo *) GetNextValueInLinkedList(options);
    }
    options=DestroyConfigureOptions(options);
  }
#endif
  /*
    Load built-in policy map.
  */
  for (i=0; i < (ssize_t) (sizeof(PolicyMap)/sizeof(*PolicyMap)); i++)
  {
    const PolicyMapInfo
      *p;
 
    PolicyInfo
      *policy_info;
 
    p=PolicyMap+i;
    policy_info=(PolicyInfo *) AcquireMagickMemory(sizeof(*policy_info));
    if (policy_info == (PolicyInfo *) NULL)
      {
        (void) ThrowMagickException(exception,GetMagickModule(),
          ResourceLimitError,"MemoryAllocationFailed","`%s'",
          p->name == (char *) NULL ? "" : p->name);
        CatchException(exception);
        continue;
      }
    (void) memset(policy_info,0,sizeof(*policy_info));
    policy_info->path=(char *) "[built-in]";
    policy_info->domain=p->domain;
    policy_info->rights=p->rights;
    policy_info->name=(char *) p->name;
    policy_info->pattern=(char *) p->pattern;
    policy_info->value=(char *) p->value;
    policy_info->exempt=MagickTrue;
    policy_info->signature=MagickCoreSignature;
    status=AppendValueToLinkedList(cache,policy_info);
    if (status == MagickFalse)
      {
        (void) ThrowMagickException(exception,GetMagickModule(),
          ResourceLimitError,"MemoryAllocationFailed","`%s'",
          p->name == (char *) NULL ? "" : p->name);
        CatchException(exception);
      }
  }
  return(cache);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   G e t P o l i c y I n f o                                                 %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetPolicyInfo() searches the policy list for the specified name and if found
%  returns attributes for that policy.
%
%  The format of the GetPolicyInfo method is:
%
%      PolicyInfo *GetPolicyInfo(const char *name,ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o name: the policy name.
%
%    o exception: return any errors or warnings in this structure.
%
*/
static PolicyInfo *GetPolicyInfo(const char *name,ExceptionInfo *exception)
{
  char
    policyname[MagickPathExtent],
    *q;
 
  ElementInfo
    *p;
 
  PolicyDomain
    domain;
 
  PolicyInfo
    *policy;
 
  assert(exception != (ExceptionInfo *) NULL);
  if (IsPolicyCacheInstantiated(exception) == MagickFalse)
    return((PolicyInfo *) NULL);
  /*
    Strip names of whitespace.
  */
  *policyname='\0';
  if (name != (const char *) NULL)
    (void) CopyMagickString(policyname,name,MagickPathExtent);
  for (q=policyname; *q != '\0'; q++)
  {
    if (isspace((int) ((unsigned char) *q)) == 0)
      continue;
    (void) CopyMagickString(q,q+1,MagickPathExtent);
    q--;
  }
  /*
    Strip domain from policy name (e.g. resource:map).
  */
  domain=UndefinedPolicyDomain;
  for (q=policyname; *q != '\0'; q++)
  {
    if (*q != ':')
      continue;
    *q='\0';
    domain=(PolicyDomain) ParseCommandOption(MagickPolicyDomainOptions,
      MagickTrue,policyname);
    (void) CopyMagickString(policyname,q+1,MagickPathExtent);
    break;
  }
  /*
    Search for policy tag.
  */
  policy=(PolicyInfo *) NULL;
  LockSemaphoreInfo(policy_semaphore);
  ResetLinkedListIterator(policy_cache);
  p=GetHeadElementInLinkedList(policy_cache);
  if ((name == (const char *) NULL) || (LocaleCompare(name,"*") == 0))
    {
      UnlockSemaphoreInfo(policy_semaphore);
      if (p != (ElementInfo *) NULL)
        policy=(PolicyInfo *) p->value;
      return(policy);
    }
  while (p != (ElementInfo *) NULL)
  {
    policy=(PolicyInfo *) p->value;
    if ((domain == UndefinedPolicyDomain) || (policy->domain == domain))
      if (LocaleCompare(policyname,policy->name) == 0)
        break;
    p=p->next;
  }
  if (p == (ElementInfo *) NULL)
    policy=(PolicyInfo *) NULL;
  else
    (void) SetHeadElementInLinkedList(policy_cache,p);
  UnlockSemaphoreInfo(policy_semaphore);
  return(policy);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   G e t P o l i c y I n f o L i s t                                         %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetPolicyInfoList() returns any policies that match the specified pattern.
%
%  The format of the GetPolicyInfoList function is:
%
%      const PolicyInfo **GetPolicyInfoList(const char *pattern,
%        size_t *number_policies,ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o pattern: Specifies a pointer to a text string containing a pattern.
%
%    o number_policies:  returns the number of policies in the list.
%
%    o exception: return any errors or warnings in this structure.
%
*/
MagickExport const PolicyInfo **GetPolicyInfoList(const char *pattern,
  size_t *number_policies,ExceptionInfo *exception)
{
  const PolicyInfo
    **policies;
 
  ElementInfo
    *p;
 
  ssize_t
    i;
 
  assert(pattern != (char *) NULL);
  assert(number_policies != (size_t *) NULL);
  if (IsEventLogging() != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",pattern);
  *number_policies=0;
  if (IsPolicyCacheInstantiated(exception) == MagickFalse)
    return((const PolicyInfo **) NULL);
  policies=(const PolicyInfo **) AcquireQuantumMemory((size_t)
    GetNumberOfElementsInLinkedList(policy_cache)+1UL,sizeof(*policies));
  if (policies == (const PolicyInfo **) NULL)
    return((const PolicyInfo **) NULL);
  LockSemaphoreInfo(policy_semaphore);
  p=GetHeadElementInLinkedList(policy_cache);
  for (i=0; p != (ElementInfo *) NULL; )
  {
    const PolicyInfo
      *policy;
 
    policy=(const PolicyInfo *) p->value;
    if ((policy->stealth == MagickFalse) &&
        (GlobExpression(policy->name,pattern,MagickFalse) != MagickFalse))
      policies[i++]=policy;
    p=p->next;
  }
  UnlockSemaphoreInfo(policy_semaphore);
  if (i == 0)
    policies=(const PolicyInfo **) RelinquishMagickMemory((void*) policies);
  else
    policies[i]=(PolicyInfo *) NULL;
  *number_policies=(size_t) i;
  return(policies);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   G e t P o l i c y L i s t                                                 %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetPolicyList() returns any policies that match the specified pattern.
%
%  The format of the GetPolicyList function is:
%
%      char **GetPolicyList(const char *pattern,size_t *number_policies,
%        ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o pattern: a pointer to a text string containing a pattern.
%
%    o number_policies:  returns the number of policies in the list.
%
%    o exception: return any errors or warnings in this structure.
%
*/
 
static char *AcquirePolicyString(const char *source,const size_t pad)
{
  char
    *destination;
 
  size_t
    length;
 
  length=0;
  if (source != (char *) NULL)
    length+=strlen(source);
  destination=(char *) NULL;
  /* AcquireMagickMemory needs to be used here to avoid an omp deadlock */
  if (~length >= pad)
    destination=(char *) AcquireMagickMemory((length+pad)*sizeof(*destination));
  if (destination == (char *) NULL)
    ThrowFatalException(ResourceLimitFatalError,"UnableToAcquireString");
  if (source != (char *) NULL)
    (void) memcpy(destination,source,length*sizeof(*destination));
  destination[length]='\0';
  return(destination);
}
 
MagickExport char **GetPolicyList(const char *pattern,size_t *number_policies,
  ExceptionInfo *exception)
{
  char
    **policies;
 
  const ElementInfo
    *p;
 
  ssize_t
    i;
 
  assert(pattern != (char *) NULL);
  assert(number_policies != (size_t *) NULL);
  if (IsEventLogging() != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",pattern);
  *number_policies=0;
  if (IsPolicyCacheInstantiated(exception) == MagickFalse)
    return((char **) NULL);
  policies=(char **) AcquireQuantumMemory((size_t)
    GetNumberOfElementsInLinkedList(policy_cache)+1UL,sizeof(*policies));
  if (policies == (char **) NULL)
    return((char **) NULL);
  LockSemaphoreInfo(policy_semaphore);
  p=GetHeadElementInLinkedList(policy_cache);
  for (i=0; p != (ElementInfo *) NULL; )
  {
    const PolicyInfo
      *policy;
 
    policy=(const PolicyInfo *) p->value;
    if ((policy->stealth == MagickFalse) &&
        (GlobExpression(policy->name,pattern,MagickFalse) != MagickFalse))
      policies[i++]=AcquirePolicyString(policy->name,1);
    p=p->next;
  }
  UnlockSemaphoreInfo(policy_semaphore);
  if (i == 0)
    policies=(char **) RelinquishMagickMemory(policies);
  else
    policies[i]=(char *) NULL;
  *number_policies=(size_t) i;
  return(policies);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   G e t P o l i c y V a l u e                                               %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetPolicyValue() returns the value associated with the named policy.
%
%  The format of the GetPolicyValue method is:
%
%      char *GetPolicyValue(const char *name)
%
%  A description of each parameter follows:
%
%    o name:  The name of the policy.
%
*/
MagickExport char *GetPolicyValue(const char *name)
{
  const char
    *value;
 
  const PolicyInfo
    *policy_info;
 
  ExceptionInfo
    *exception;
 
  assert(name != (const char *) NULL);
  if (IsEventLogging() != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",name);
  exception=AcquireExceptionInfo();
  policy_info=GetPolicyInfo(name,exception);
  exception=DestroyExceptionInfo(exception);
  if (policy_info == (PolicyInfo *) NULL)
    return((char *) NULL);
  value=policy_info->value;
  if ((value == (const char *) NULL) || (*value == '\0'))
    return((char *) NULL);
  return(AcquirePolicyString(value,1));
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   I s P a t h A u t h o r i z e d                                           %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  IsPathAuthorized() determines if the specified path is authorized based on
%  the current policy settings.
%
%  The format of the IsPathAuthorized method is:
%
%      MagickBooleanType IsPathAuthorized(const PolicyRights rights, 
%        const char *path)
%
%  A description of each parameter follows.
%
%    o rights: The policy rights to check.
%
%    o path: The path to check.
%
*/
static inline MagickBooleanType IsPathContainsSymlink(const char *path)
{
  char
    partial[MagickPathExtent];
 
  const char
    *p;
 
  ssize_t
    offset = 0;
 
  if (path == (const char *) NULL)
    return(MagickFalse);
  *partial='\0';
  p=path;
  if (*p == *DirectorySeparator)
    {
      /*
        Path starts with a directory separator, include it.
      */
      if ((offset+1) >= (ssize_t) sizeof(partial))
        return(MagickFalse);
      partial[offset++]=(*p++);
      partial[offset]='\0';
    }
  while (*p != '\0')
  {
    char
      component[MagickPathExtent];
 
    ssize_t
      i = 0;
 
    /*
      Copy next component into a temporary buffer.
    */
    while ((*p != '\0') && (*p != *DirectorySeparator) &&
           ((i+1) < (ssize_t) sizeof(component)))
      component[i++]=(*p++);
    component[i]='\0';
    if (i == 0)
      {
        /*
          skip repeated separators.
        */
        if (*p == *DirectorySeparator)
          p++;
        continue;
      }
    if ((offset > 0) && (partial[offset-1] != *DirectorySeparator))
      {
        /*
          Append separator if needed.
        */
        if ((offset+1) >= (ssize_t) sizeof(partial))
          return MagickFalse;
        partial[offset++]=(*DirectorySeparator);
        partial[offset]='\0';
      }
    /*
      Append component.
    */
    if ((offset+i) >= (ssize_t) sizeof(partial))
      return(MagickFalse);
    (void) memcpy(partial+offset,component,i);
    offset+=i;
    partial[offset]='\0';
    if (*p != '\0')
      {
        /*
          Check whether this prefix is a symlink.
        */
        if (is_symlink_utf8(partial) != MagickFalse)
          return(MagickTrue);
      }
    /*
      Skip separator.
    */
    if (*p == *DirectorySeparator)
      p++;
  }
  return(MagickFalse);
}
 
MagickExport MagickBooleanType IsPathAuthorized(const PolicyRights rights,
  const char *path)
{
  MagickBooleanType symlink_follow_allowed = IsRightsAuthorizedByName(
    SystemPolicyDomain,"symlink",rights,"follow");
  MagickBooleanType status =
    ((IsRightsAuthorized(PathPolicyDomain,rights,path) != MagickFalse) &&
    ((symlink_follow_allowed != MagickFalse) ||
     (is_symlink_utf8(path) == MagickFalse))) ? MagickTrue : MagickFalse;
  if ((status != MagickFalse) && (symlink_follow_allowed == MagickFalse))
    {
      if ((is_symlink_utf8(path) != MagickFalse) ||
          (IsPathContainsSymlink(path) != MagickFalse))
        status=MagickFalse;
    }
  if (status != MagickFalse)
    status=IsFileResourceIdentityValid(path);
  return(status);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   I s P o l i c y C a c h e I n s t a n t i a t e d                         %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  IsPolicyCacheInstantiated() determines if the policy list is instantiated.
%  If not, it instantiates the list and returns it.
%
%  The format of the IsPolicyInstantiated method is:
%
%      MagickBooleanType IsPolicyCacheInstantiated(ExceptionInfo *exception)
%
%  A description of each parameter follows.
%
%    o exception: return any errors or warnings in this structure.
%
*/
static MagickBooleanType IsPolicyCacheInstantiated(ExceptionInfo *exception)
{
  if (policy_cache == (LinkedListInfo *) NULL)
    {
      (void) GetMaxMemoryRequest();  /* avoid OMP deadlock */
      if (policy_semaphore == (SemaphoreInfo *) NULL)
        ActivateSemaphoreInfo(&policy_semaphore);
      LockSemaphoreInfo(policy_semaphore);
      if (policy_cache == (LinkedListInfo *) NULL)
        policy_cache=AcquirePolicyCache(PolicyFilename,exception);
      UnlockSemaphoreInfo(policy_semaphore);
    }
  return(policy_cache != (LinkedListInfo *) NULL ? MagickTrue : MagickFalse);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   I s R i g h t s A u t h o r i z e d                                       %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  IsRightsAuthorized() returns MagickTrue if the policy authorizes the
%  requested rights for the specified domain.
%
%  Policy evaluation uses a “last match wins” model.  Be careful when adding
%  new rules: any later policy can override earlier denies or allows. Place
%  broad deny rules first, followed by specific exceptions, and review
%  ordering to avoid accidental authorization.
%
%  The format of the IsRightsAuthorized method is:
%
%      MagickBooleanType IsRightsAuthorized(const PolicyDomain domain,
%        const PolicyRights rights,const char *pattern)
%
%  A description of each parameter follows:
%
%    o domain: the policy domain.
%
%    o rights: the policy rights.
%
%    o pattern: the pattern.
%
*/
 
MagickExport MagickBooleanType IsRightsAuthorizedByName(
  const PolicyDomain domain,const char *name,const PolicyRights rights,
  const char *pattern)
{
  char
    *canonical_directory = (char *) NULL,
    *canonical_path = (char *) NULL,
    *canonical_candidate = (char *) NULL,
    directory[MagickPathExtent],
    filename[MagickPathExtent];
 
  ElementInfo
    *p;
 
  ExceptionInfo
    *exception;
 
  MagickBooleanType
    canonical_matched_any = MagickFalse,
    matched_any = MagickFalse,
    paths_provisioned = MagickFalse,
    status;
 
  PolicyRights
    canonical_allowed_accumulator = AllPolicyRights,
    effective_rights = AllPolicyRights;
 
  /*
    Load policies.
  */
  if ((GetLogEventMask() & PolicyEvent) != 0)
    (void) LogMagickEvent(PolicyEvent,GetMagickModule(),
      "Domain: %s; name: %s; rights=%s; pattern=\"%s\"; ...",
      CommandOptionToMnemonic(MagickPolicyDomainOptions,domain),
      name == (const char *) NULL ? "undefined" : name,
      CommandOptionToMnemonic(MagickPolicyRightsOptions,rights),
      pattern == (const char *) NULL ? "undefined" : pattern);
  exception=AcquireExceptionInfo();
  status=IsPolicyCacheInstantiated(exception);
  exception=DestroyExceptionInfo(exception);
  if (status == MagickFalse)
    {
      if ((GetLogEventMask() & PolicyEvent) != 0)
        (void) LogMagickEvent(PolicyEvent,GetMagickModule(),
          "  authorized: true (no security policies found)");
      return(MagickTrue);
    }
  /*
    Evaluate policies in order; last match wins, however, canonical denies are
    enforced after evaluation.
  */
  LockSemaphoreInfo(policy_semaphore);
  ResetLinkedListIterator(policy_cache);
  p=GetHeadElementInLinkedList(policy_cache);
  for ( ; p != (ElementInfo *) NULL; p=p->next)
  {
    const PolicyInfo
      *policy = (PolicyInfo *) p->value;
 
    MagickBooleanType
      match = MagickFalse,
      matched_canonical = MagickFalse;
 
    if (policy->domain != domain)
      continue;
    if ((name != (char *) NULL) && (LocaleCompare(name,policy->name) != 0))
      continue;
    match=GlobExpression(pattern,policy->pattern,MagickFalse);
    if (policy->domain == PathPolicyDomain)
      {
        if (paths_provisioned == MagickFalse)
          {
            /*
              Generate directory, basename, and canonical path.
            */
            paths_provisioned=MagickTrue;
            GetPathComponent(pattern,HeadPath,directory);
            GetPathComponent(pattern,TailPath,filename);
            canonical_directory=realpath_utf8(directory);
            if ((canonical_directory != (char *) NULL) && (*filename != '\0'))
              {
                size_t
                  length;
 
                length=strlen(canonical_directory)+strlen(filename)+2;
                canonical_candidate=(char *) AcquireCriticalMemory(length*
                  sizeof(*canonical_candidate));
                if (canonical_candidate != (char *) NULL)
                  (void) FormatLocaleString(canonical_candidate,length,"%s%s%s",
                    canonical_directory,DirectorySeparator,filename);
              }
            canonical_path=realpath_utf8(pattern);
          }
        /*
          Match against directory, basename, and canonical path.
        */
        if ((canonical_directory != (char *) NULL) && (match == MagickFalse))
          match=GlobExpression(canonical_directory,policy->pattern,MagickFalse);
        if ((canonical_candidate != (char *) NULL) && (match == MagickFalse))
          match=GlobExpression(canonical_candidate,policy->pattern,MagickFalse);
        if ((canonical_path != (char *) NULL) && (match == MagickFalse))
          match=GlobExpression(canonical_path,policy->pattern,MagickFalse);
        if ((canonical_path != (char *) NULL) &&
            (GlobExpression(canonical_path,policy->pattern,MagickFalse) != MagickFalse))
          matched_canonical=MagickTrue;
        else
          if ((canonical_candidate != (char *) NULL) &&
              (GlobExpression(canonical_candidate,policy->pattern,MagickFalse) != MagickFalse))
            matched_canonical=MagickTrue;
          else
           if ((canonical_directory != (char *) NULL) &&
               (GlobExpression(canonical_directory,policy->pattern,MagickFalse) != MagickFalse))
             matched_canonical=MagickTrue;
      }
    if (match == MagickFalse)
      continue;
    matched_any=MagickTrue;
    effective_rights=policy->rights;
    if (matched_canonical != MagickFalse)
      {
        /*
          If this match was against a canonical form, accumulate allowed rights.
        */
        canonical_matched_any=MagickTrue;
        canonical_allowed_accumulator&=policy->rights;
      }
  }
  UnlockSemaphoreInfo(policy_semaphore);
  if (canonical_directory != (char *) NULL)
    canonical_directory=DestroyString(canonical_directory);
  if (canonical_candidate != (char *) NULL)
    canonical_candidate=DestroyString(canonical_candidate);
  if (canonical_path != (char *) NULL)
    canonical_path=DestroyString(canonical_path);
  /*
    Is rights authorized?
  */
  status=MagickTrue;
  if (matched_any != MagickFalse)
    {
      if (((rights & ReadPolicyRights) != 0) &&
          ((effective_rights & ReadPolicyRights) == 0))
        status=MagickFalse;
      if (((rights & WritePolicyRights) != 0) &&
          ((effective_rights & WritePolicyRights) == 0))
        status=MagickFalse;
      if (((rights & ExecutePolicyRights) != 0) &&
          ((effective_rights & ExecutePolicyRights) == 0))
        status=MagickFalse;
    }
  /*
    Enforce sticky canonical denies.
  */
  if (canonical_matched_any != MagickFalse)
    {
      PolicyRights canonical_denied_mask = (AllPolicyRights &
        ~canonical_allowed_accumulator);
      if ((canonical_denied_mask & rights) != 0)
        status=MagickFalse;
    }
  if ((GetLogEventMask() & PolicyEvent) != 0)
    (void) LogMagickEvent(PolicyEvent,GetMagickModule(),
      "  authorized: %s",status == MagickFalse ? "false" : "true");
  return(status);
}
 
MagickExport MagickBooleanType IsRightsAuthorized(const PolicyDomain domain,
  const PolicyRights rights,const char *pattern)
{
  return(IsRightsAuthorizedByName(domain,(const char *) NULL,rights,pattern));
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%  L i s t P o l i c y I n f o                                                %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  ListPolicyInfo() lists policies to the specified file.
%
%  The format of the ListPolicyInfo method is:
%
%      MagickBooleanType ListPolicyInfo(FILE *file,ExceptionInfo *exception)
%
%  A description of each parameter follows.
%
%    o file:  List policy names to this file handle.
%
%    o exception: return any errors or warnings in this structure.
%
*/
MagickExport MagickBooleanType ListPolicyInfo(FILE *file,
  ExceptionInfo *exception)
{
  const char
    *path,
    *domain;
 
  const PolicyInfo
    **policy_info;
 
  ssize_t
    i;
 
  size_t
    number_policies;
 
  /*
    List name and attributes of each policy in the list.
  */
  if (file == (const FILE *) NULL)
    file=stdout;
  policy_info=GetPolicyInfoList("*",&number_policies,exception);
  if (policy_info == (const PolicyInfo **) NULL)
    return(MagickFalse);
  path=(const char *) NULL;
  for (i=0; i < (ssize_t) number_policies; i++)
  {
    if (policy_info[i]->stealth != MagickFalse)
      continue;
    if (((path == (const char *) NULL) ||
         (LocaleCompare(path,policy_info[i]->path) != 0)) &&
         (policy_info[i]->path != (char *) NULL))
      (void) FormatLocaleFile(file,"\nPath: %s\n",policy_info[i]->path);
    path=policy_info[i]->path;
    domain=CommandOptionToMnemonic(MagickPolicyDomainOptions,
      policy_info[i]->domain);
    (void) FormatLocaleFile(file,"  Policy: %s\n",domain);
    if ((policy_info[i]->domain == CachePolicyDomain) ||
        (policy_info[i]->domain == ResourcePolicyDomain) ||
        (policy_info[i]->domain == SystemPolicyDomain))
      {
        if (policy_info[i]->name != (char *) NULL)
          (void) FormatLocaleFile(file,"    name: %s\n",policy_info[i]->name);
        if (policy_info[i]->value != (char *) NULL)
          (void) FormatLocaleFile(file,"    value: %s\n",policy_info[i]->value);
      }
    else
      {
        (void) FormatLocaleFile(file,"    rights: ");
        if (policy_info[i]->rights == NoPolicyRights)
          (void) FormatLocaleFile(file,"None ");
        if ((policy_info[i]->rights & ReadPolicyRights) != 0)
          (void) FormatLocaleFile(file,"Read ");
        if ((policy_info[i]->rights & WritePolicyRights) != 0)
          (void) FormatLocaleFile(file,"Write ");
        if ((policy_info[i]->rights & ExecutePolicyRights) != 0)
          (void) FormatLocaleFile(file,"Execute ");
        (void) FormatLocaleFile(file,"\n");
        if (policy_info[i]->pattern != (char *) NULL)
          (void) FormatLocaleFile(file,"    pattern: %s\n",
            policy_info[i]->pattern);
      }
  }
  policy_info=(const PolicyInfo **) RelinquishMagickMemory((void *)
    policy_info);
  (void) fflush(file);
  return(MagickTrue);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   L o a d P o l i c y C a c h e                                             %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  LoadPolicyCache() loads the policy configurations which provides a mapping
%  between policy attributes and a policy domain.
%
%  The format of the LoadPolicyCache method is:
%
%      MagickBooleanType LoadPolicyCache(LinkedListInfo *cache,const char *xml,
%        const char *filename,const size_t depth,ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o xml:  The policy list in XML format.
%
%    o filename:  The policy list filename.
%
%    o depth: depth of <include /> statements.
%
%    o exception: return any errors or warnings in this structure.
%
*/
static MagickBooleanType LoadPolicyCache(LinkedListInfo *cache,
  const char *policy,const char *filename,const size_t depth,
  ExceptionInfo *exception)
{
  char
    keyword[MagickPathExtent],
    *token;
 
  const char
    *q;
 
  MagickStatusType
    status;
 
  PolicyInfo
    *policy_info;
 
  size_t
    extent;
 
  /*
    Load the policy map file.
  */
  (void) LogMagickEvent(ConfigureEvent,GetMagickModule(),
    "Loading policy file \"%s\" ...",filename);
  if (policy == (char *) NULL)
    return(MagickFalse);
  status=MagickTrue;
  policy_info=(PolicyInfo *) NULL;
  token=AcquirePolicyString(policy,MagickPathExtent);
  extent=strlen(token)+MagickPathExtent;
  for (q=policy; *q != '\0'; )
  {
    /*
      Interpret XML.
    */
    (void) GetNextToken(q,&q,extent,token);
    if (*token == '\0')
      break;
    (void) CopyMagickString(keyword,token,MagickPathExtent);
    if (LocaleNCompare(keyword,"<!DOCTYPE",9) == 0)
      {
        /*
          Docdomain element.
        */
        while ((LocaleNCompare(q,"]>",2) != 0) && (*q != '\0'))
          (void) GetNextToken(q,&q,extent,token);
        continue;
      }
    if (LocaleNCompare(keyword,"<!--",4) == 0)
      {
        /*
          Comment element.
        */
        while ((LocaleNCompare(q,"->",2) != 0) && (*q != '\0'))
          (void) GetNextToken(q,&q,extent,token);
        continue;
      }
    if (LocaleCompare(keyword,"<include") == 0)
      {
        /*
          Include element.
        */
        while (((*token != '/') && (*(token+1) != '>')) && (*q != '\0'))
        {
          (void) CopyMagickString(keyword,token,MagickPathExtent);
          (void) GetNextToken(q,&q,extent,token);
          if (*token != '=')
            continue;
          (void) GetNextToken(q,&q,extent,token);
          if (LocaleCompare(keyword,"file") == 0)
            {
              if (depth > MagickMaxRecursionDepth)
                (void) ThrowMagickException(exception,GetMagickModule(),
                  ConfigureError,"IncludeElementNestedTooDeeply","`%s'",token);
              else
                {
                  char
                    path[MagickPathExtent],
                    *file_xml;
 
                  GetPathComponent(filename,HeadPath,path);
                  if (*path != '\0')
                    (void) ConcatenateMagickString(path,DirectorySeparator,
                      MagickPathExtent);
                  if (*token == *DirectorySeparator)
                    (void) CopyMagickString(path,token,MagickPathExtent);
                  else
                    (void) ConcatenateMagickString(path,token,MagickPathExtent);
                  file_xml=FileToXML(path,~0UL);
                  if (file_xml != (char *) NULL)
                    {
                      status&=(MagickStatusType) LoadPolicyCache(cache,file_xml,
                        path,depth+1,exception);
                      file_xml=DestroyString(file_xml);
                    }
                }
            }
        }
        continue;
      }
    if (LocaleCompare(keyword,"<policy") == 0)
      {
        /*
          Policy element.
        */
        policy_info=(PolicyInfo *) AcquireCriticalMemory(sizeof(*policy_info));
        (void) memset(policy_info,0,sizeof(*policy_info));
        policy_info->path=AcquirePolicyString(filename,1);
        policy_info->exempt=MagickFalse;
        policy_info->signature=MagickCoreSignature;
        continue;
      }
    if (policy_info == (PolicyInfo *) NULL)
      continue;
    if ((LocaleCompare(keyword,"/>") == 0) ||
        (LocaleCompare(keyword,"</policy>") == 0))
      {
        status=AppendValueToLinkedList(cache,policy_info);
        if (status == MagickFalse)
          (void) ThrowMagickException(exception,GetMagickModule(),
            ResourceLimitError,"MemoryAllocationFailed","`%s'",
            policy_info->name);
        policy_info=(PolicyInfo *) NULL;
        continue;
      }
    (void) GetNextToken(q,(const char **) NULL,extent,token);
    if (*token != '=')
      continue;
    (void) GetNextToken(q,&q,extent,token);
    (void) GetNextToken(q,&q,extent,token);
    switch (*keyword)
    {
      case 'D':
      case 'd':
      {
        if (LocaleCompare((char *) keyword,"domain") == 0)
          {
            policy_info->domain=(PolicyDomain) ParseCommandOption(
              MagickPolicyDomainOptions,MagickTrue,token);
            break;
          }
        break;
      }
      case 'N':
      case 'n':
      {
        if (LocaleCompare((char *) keyword,"name") == 0)
          {
            policy_info->name=AcquirePolicyString(token,1);
            break;
          }
        break;
      }
      case 'P':
      case 'p':
      {
        if (LocaleCompare((char *) keyword,"pattern") == 0)
          {
            policy_info->pattern=AcquirePolicyString(token,1);
            break;
          }
        break;
      }
      case 'R':
      case 'r':
      {
        if (LocaleCompare((char *) keyword,"rights") == 0)
          {
            policy_info->rights=(PolicyRights) ParseCommandOption(
              MagickPolicyRightsOptions,MagickTrue,token);
            break;
          }
        break;
      }
      case 'S':
      case 's':
      {
        if (LocaleCompare((char *) keyword,"stealth") == 0)
          {
            policy_info->stealth=IsStringTrue(token);
            break;
          }
        break;
      }
      case 'V':
      case 'v':
      {
        if (LocaleCompare((char *) keyword,"value") == 0)
          {
            policy_info->value=AcquirePolicyString(token,1);
            break;
          }
        break;
      }
      default:
        break;
    }
  }
  token=(char *) RelinquishMagickMemory(token);
  return(status != 0 ? MagickTrue : MagickFalse);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   P o l i c y C o m p o n e n t G e n e s i s                               %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  PolicyComponentGenesis() instantiates the policy component.
%
%  The format of the PolicyComponentGenesis method is:
%
%      MagickBooleanType PolicyComponentGenesis(void)
%
*/
MagickPrivate MagickBooleanType PolicyComponentGenesis(void)
{
  if (policy_semaphore == (SemaphoreInfo *) NULL)
    policy_semaphore=AcquireSemaphoreInfo();
  return(MagickTrue);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   P o l i c y C o m p o n e n t T e r m i n u s                             %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  PolicyComponentTerminus() destroys the policy component.
%
%  The format of the PolicyComponentTerminus method is:
%
%      PolicyComponentTerminus(void)
%
*/
 
static void *DestroyPolicyElement(void *policy_info)
{
  PolicyInfo
    *p;
 
  p=(PolicyInfo *) policy_info;
  if (p->exempt == MagickFalse)
    {
      if (p->value != (char *) NULL)
        p->value=DestroyString(p->value);
      if (p->pattern != (char *) NULL)
        p->pattern=DestroyString(p->pattern);
      if (p->name != (char *) NULL)
        p->name=DestroyString(p->name);
      if (p->path != (char *) NULL)
        p->path=DestroyString(p->path);
    }
  p=(PolicyInfo *) RelinquishMagickMemory(p);
  return((void *) NULL);
}
 
MagickPrivate void PolicyComponentTerminus(void)
{
  if (policy_semaphore == (SemaphoreInfo *) NULL)
    ActivateSemaphoreInfo(&policy_semaphore);
  LockSemaphoreInfo(policy_semaphore);
  if (policy_cache != (LinkedListInfo *) NULL)
    policy_cache=DestroyLinkedList(policy_cache,DestroyPolicyElement);
  UnlockSemaphoreInfo(policy_semaphore);
  RelinquishSemaphoreInfo(&policy_semaphore);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%  S e t M a g i c k S e c u r i t y P o l i c y                              %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  SetMagickSecurityPolicy() sets or restricts the ImageMagick security policy.
%  It returns MagickFalse if the policy the policy does not parse.
%
%  The format of the SetMagickSecurityPolicy method is:
%
%      MagickBooleanType SetMagickSecurityPolicy(const char *policy,
%        ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o policy: the security policy in the XML format.
%
%    o exception: return any errors or warnings in this structure.
%
*/
 
static MagickBooleanType ValidateSecurityPolicy(const char *policy,
  const char *url,ExceptionInfo *exception)
{
#if defined(MAGICKCORE_XML_DELEGATE)
  xmlDocPtr
    document;
 
  /*
    Parse security policy.
  */
  document=xmlReadMemory(policy,(int) strlen(policy),url,NULL,
    XML_PARSE_NOERROR | XML_PARSE_NOWARNING);
  if (document == (xmlDocPtr) NULL)
    {
      (void) ThrowMagickException(exception,GetMagickModule(),ConfigureError,
        "PolicyValidationException","'%s'",url);
      return(MagickFalse);
    }
  xmlFreeDoc(document);
#else
  (void) policy;
  (void) url;
  (void) exception;
#endif
  return(MagickTrue);
}
 
MagickExport MagickBooleanType SetMagickSecurityPolicy(const char *policy,
  ExceptionInfo *exception)
{
  MagickBooleanType
    status;
 
  LinkedListInfo
    *user_policies;
 
  PolicyInfo
    *p;
 
  /*
    Load user policies.
  */
  assert(exception != (ExceptionInfo *) NULL);
  if (policy == (const char *) NULL)
    return(MagickFalse);
  if (ValidateSecurityPolicy(policy,PolicyFilename,exception) == MagickFalse)
    return(MagickFalse);
  status=LoadPolicyCache(policy_cache,policy,"[user-policy]",0,exception);
  if (status == MagickFalse)
    return(status);
  /*
    Synchronize user policies.
  */
  user_policies=NewLinkedList(0);
  status=LoadPolicyCache(user_policies,policy,"[user-policy]",0,exception);
  if (status == MagickFalse)
    {
      user_policies=DestroyLinkedList(user_policies,DestroyPolicyElement);
      return(MagickFalse);
    }
  ResetLinkedListIterator(user_policies);
  p=(PolicyInfo *) GetNextValueInLinkedList(user_policies);
  while (p != (PolicyInfo *) NULL)
  {
    if ((p->name != (char *) NULL) && (p->value != (char *) NULL))
      (void) SetMagickSecurityPolicyValue(p->domain,p->name,p->value,exception);
    p=(PolicyInfo *) GetNextValueInLinkedList(user_policies);
  }
  user_policies=DestroyLinkedList(user_policies,DestroyPolicyElement);
  return(status);
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%  S e t M a g i c k S e c u r i t y P o l i c y V a l u e                    %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  SetMagickSecurityPolicyValue() sets a value associated with an ImageMagick
%  security policy.  For most policies, the value must be less than any value
%  set by the security policy configuration file (i.e. policy.xml).  It returns
%  MagickFalse if the policy cannot be modified or if the policy does not parse.
%
%  The format of the SetMagickSecurityPolicyValue method is:
%
%      MagickBooleanType SetMagickSecurityPolicyValue(
%        const PolicyDomain domain,const char *name,const char *value,
%        ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o domain: the domain of the policy (e.g. system, resource).
%
%    o name: the name of the policy.
%
%    o value: the value to set the policy to.
%
%    o exception: return any errors or warnings in this structure.
%
*/
MagickExport MagickBooleanType SetMagickSecurityPolicyValue(
  const PolicyDomain domain,const char *name,const char *value,
  ExceptionInfo *exception)
{
  magick_unreferenced(exception);
  assert(exception != (ExceptionInfo *) NULL);
  if ((name == (const char *) NULL) || (value == (const char *) NULL))
    return(MagickFalse);
  switch (domain)
  {
    case CachePolicyDomain:
    {
      if (LocaleCompare(name,"memory-map") == 0)
        {
          if (LocaleCompare(value,"anonymous") != 0)
            return(MagickFalse);
          ResetCacheAnonymousMemory();
          ResetStreamAnonymousMemory();
          return(MagickTrue);
        }
      break;
    }
    case ResourcePolicyDomain:
    {
      ssize_t
        type;
 
      type=ParseCommandOption(MagickResourceOptions,MagickFalse,name);
      if (type >= 0)
        {
          MagickSizeType
            limit;
 
          limit=MagickResourceInfinity;
          if (LocaleCompare("unlimited",value) != 0)
            limit=StringToMagickSizeType(value,100.0);
          if ((ResourceType) type == TimeResource)
            limit=(MagickSizeType) ParseMagickTimeToLive(value);
          return(SetMagickResourceLimit((ResourceType) type,limit));
        }
      break;
    }
    case SystemPolicyDomain:
    {
      if (LocaleCompare(name,"max-memory-request") == 0)
        {
          MagickSizeType
            limit;
 
          limit=MagickResourceInfinity;
          if (LocaleCompare("unlimited",value) != 0)
            limit=StringToMagickSizeType(value,100.0);
          SetMaxMemoryRequest(limit);
          return(MagickTrue);
        }
      if (LocaleCompare(name,"max-profile-size") == 0)
        {
          MagickSizeType
            limit;
 
          limit=MagickResourceInfinity;
          if (LocaleCompare("unlimited",value) != 0)
            limit=StringToMagickSizeType(value,100.0);
          SetMaxProfileSize(limit);
          return(MagickTrue);
        }
      if (LocaleCompare(name,"memory-map") == 0)
        {
          if (LocaleCompare(value,"anonymous") != 0)
            return(MagickFalse);
          ResetVirtualAnonymousMemory();
          return(MagickTrue);
        }
      if (LocaleCompare(name,"precision") == 0)
        {
          int
            limit;
 
          limit=StringToInteger(value);
          SetMagickPrecision(limit);
          return(MagickTrue);
        }
      break;
    }
    case CoderPolicyDomain:
    case DelegatePolicyDomain:
    case FilterPolicyDomain:
    case ModulePolicyDomain:
    case PathPolicyDomain:
    default:
      break;
  }
  return(MagickFalse);
}