extensions/permissions/nsContentBlocker.cpp
author Ehsan Akhgari <ehsan@mozilla.com>
Wed, 12 Dec 2012 00:05:49 -0500
changeset 115629 553a3bcf1fe771c09cdfd1640e8059c312622b4a
parent 113853 0f76932d28c58881dd87455b031b71e90770c7b1
child 149563 f2c7e4e24beaff00360dad9b26d12b46743af47b
permissions -rw-r--r--
Backed out 7 changesets (bug 769288) because of leaks Backed out changeset b2fb475b6e4e (bug 769288) Backed out changeset 912331d0c2fd (bug 769288) Backed out changeset 6d8d78bd56a9 (bug 769288) Backed out changeset e75cd1e1fca3 (bug 769288) Backed out changeset e10c24f10bd2 (bug 769288) Backed out changeset 7b0fdedb4fa9 (bug 769288) Backed out changeset 42b468942a84 (bug 769288)

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsContentBlocker.h"
#include "nsIContent.h"
#include "nsIURI.h"
#include "nsIServiceManager.h"
#include "nsIDocShellTreeItem.h"
#include "nsIPrefService.h"
#include "nsIPrefBranch.h"
#include "nsIDocShell.h"
#include "nsString.h"
#include "nsContentPolicyUtils.h"
#include "nsIObjectLoadingContent.h"

// Possible behavior pref values
// Those map to the nsIPermissionManager values where possible
#define BEHAVIOR_ACCEPT nsIPermissionManager::ALLOW_ACTION
#define BEHAVIOR_REJECT nsIPermissionManager::DENY_ACTION
#define BEHAVIOR_NOFOREIGN 3

// From nsIContentPolicy
static const char *kTypeString[] = {"other",
                                    "script",
                                    "image",
                                    "stylesheet",
                                    "object",
                                    "document",
                                    "subdocument",
                                    "refresh",
                                    "xbl",
                                    "ping",
                                    "xmlhttprequest",
                                    "objectsubrequest",
                                    "dtd",
                                    "font",
                                    "media",
                                    "websocket"
                                    "csp_report"};

#define NUMBER_OF_TYPES NS_ARRAY_LENGTH(kTypeString)
uint8_t nsContentBlocker::mBehaviorPref[NUMBER_OF_TYPES];

NS_IMPL_ISUPPORTS3(nsContentBlocker, 
                   nsIContentPolicy,
                   nsIObserver,
                   nsSupportsWeakReference)

nsContentBlocker::nsContentBlocker()
{
  memset(mBehaviorPref, BEHAVIOR_ACCEPT, NUMBER_OF_TYPES);
}

nsresult
nsContentBlocker::Init()
{
  nsresult rv;
  mPermissionManager = do_GetService(NS_PERMISSIONMANAGER_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIPrefService> prefService = do_GetService(NS_PREFSERVICE_CONTRACTID, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIPrefBranch> prefBranch;
  rv = prefService->GetBranch("permissions.default.", getter_AddRefs(prefBranch));
  NS_ENSURE_SUCCESS(rv, rv);

  // Migrate old image blocker pref
  nsCOMPtr<nsIPrefBranch> oldPrefBranch;
  oldPrefBranch = do_QueryInterface(prefService);
  int32_t oldPref;
  rv = oldPrefBranch->GetIntPref("network.image.imageBehavior", &oldPref);
  if (NS_SUCCEEDED(rv) && oldPref) {
    int32_t newPref;
    switch (oldPref) {
      default:
        newPref = BEHAVIOR_ACCEPT;
        break;
      case 1:
        newPref = BEHAVIOR_NOFOREIGN;
        break;
      case 2:
        newPref = BEHAVIOR_REJECT;
        break;
    }
    prefBranch->SetIntPref("image", newPref);
    oldPrefBranch->ClearUserPref("network.image.imageBehavior");
  }


  // The branch is not a copy of the prefservice, but a new object, because
  // it is a non-default branch. Adding obeservers to it will only work if
  // we make sure that the object doesn't die. So, keep a reference to it.
  mPrefBranchInternal = do_QueryInterface(prefBranch, &rv);
  NS_ENSURE_SUCCESS(rv, rv);

  rv = mPrefBranchInternal->AddObserver("", this, true);
  PrefChanged(prefBranch, nullptr);

  return rv;
}

#undef  LIMIT
#define LIMIT(x, low, high, default) ((x) >= (low) && (x) <= (high) ? (x) : (default))

void
nsContentBlocker::PrefChanged(nsIPrefBranch *aPrefBranch,
                              const char    *aPref)
{
  int32_t val;

#define PREF_CHANGED(_P) (!aPref || !strcmp(aPref, _P))

  for(uint32_t i = 0; i < NUMBER_OF_TYPES; ++i) {
    if (PREF_CHANGED(kTypeString[i]) &&
        NS_SUCCEEDED(aPrefBranch->GetIntPref(kTypeString[i], &val)))
      mBehaviorPref[i] = LIMIT(val, 1, 3, 1);
  }

}

// nsIContentPolicy Implementation
NS_IMETHODIMP 
nsContentBlocker::ShouldLoad(uint32_t          aContentType,
                             nsIURI           *aContentLocation,
                             nsIURI           *aRequestingLocation,
                             nsISupports      *aRequestingContext,
                             const nsACString &aMimeGuess,
                             nsISupports      *aExtra,
                             nsIPrincipal     *aRequestPrincipal,
                             int16_t          *aDecision)
{
  *aDecision = nsIContentPolicy::ACCEPT;
  nsresult rv;

  // Ony support NUMBER_OF_TYPES content types. that all there is at the
  // moment, but you never know...
  if (aContentType > NUMBER_OF_TYPES)
    return NS_OK;
  
  // we can't do anything without this
  if (!aContentLocation)
    return NS_OK;

  // The final type of an object tag may mutate before it reaches
  // shouldProcess, so we cannot make any sane blocking decisions here
  if (aContentType == nsIContentPolicy::TYPE_OBJECT)
    return NS_OK;
  
  // we only want to check http, https, ftp
  // for chrome:// and resources and others, no need to check.
  nsAutoCString scheme;
  aContentLocation->GetScheme(scheme);
  if (!scheme.LowerCaseEqualsLiteral("ftp") &&
      !scheme.LowerCaseEqualsLiteral("http") &&
      !scheme.LowerCaseEqualsLiteral("https"))
    return NS_OK;

  bool shouldLoad, fromPrefs;
  rv = TestPermission(aContentLocation, aRequestingLocation, aContentType,
                      &shouldLoad, &fromPrefs);
  NS_ENSURE_SUCCESS(rv, rv);
  if (!shouldLoad) {
    if (fromPrefs) {
      *aDecision = nsIContentPolicy::REJECT_TYPE;
    } else {
      *aDecision = nsIContentPolicy::REJECT_SERVER;
    }
  }

  return NS_OK;
}

NS_IMETHODIMP
nsContentBlocker::ShouldProcess(uint32_t          aContentType,
                                nsIURI           *aContentLocation,
                                nsIURI           *aRequestingLocation,
                                nsISupports      *aRequestingContext,
                                const nsACString &aMimeGuess,
                                nsISupports      *aExtra,
                                nsIPrincipal     *aRequestPrincipal,
                                int16_t          *aDecision)
{
  // For loads where aRequestingContext is chrome, we should just
  // accept.  Those are most likely toplevel loads in windows, and
  // chrome generally knows what it's doing anyway.
  nsCOMPtr<nsIDocShellTreeItem> item =
    do_QueryInterface(NS_CP_GetDocShellFromContext(aRequestingContext));

  if (item) {
    int32_t type;
    item->GetItemType(&type);
    if (type == nsIDocShellTreeItem::typeChrome) {
      *aDecision = nsIContentPolicy::ACCEPT;
      return NS_OK;
    }
  }

  // For objects, we only check policy in shouldProcess, as the final type isn't
  // determined until the channel is open -- We don't want to block images in
  // object tags because plugins are disallowed.
  // NOTE that this bypasses the aContentLocation checks in ShouldLoad - this is
  // intentional, as aContentLocation may be null for plugins that load by type
  // (e.g. java)
  if (aContentType == nsIContentPolicy::TYPE_OBJECT) {
    *aDecision = nsIContentPolicy::ACCEPT;

    bool shouldLoad, fromPrefs;
    nsresult rv = TestPermission(aContentLocation, aRequestingLocation,
                                 aContentType, &shouldLoad, &fromPrefs);
    NS_ENSURE_SUCCESS(rv, rv);
    if (!shouldLoad) {
      if (fromPrefs) {
        *aDecision = nsIContentPolicy::REJECT_TYPE;
      } else {
        *aDecision = nsIContentPolicy::REJECT_SERVER;
      }
    }
    return NS_OK;
  }
  
  // This isn't a load from chrome or an object tag - Just do a ShouldLoad()
  // check -- we want the same answer here
  return ShouldLoad(aContentType, aContentLocation, aRequestingLocation,
                    aRequestingContext, aMimeGuess, aExtra, aRequestPrincipal,
                    aDecision);
}

nsresult
nsContentBlocker::TestPermission(nsIURI *aCurrentURI,
                                 nsIURI *aFirstURI,
                                 int32_t aContentType,
                                 bool *aPermission,
                                 bool *aFromPrefs)
{
  *aFromPrefs = false;
  // This default will also get used if there is an unknown value in the
  // permission list, or if the permission manager returns unknown values.
  *aPermission = true;

  // check the permission list first; if we find an entry, it overrides
  // default prefs.
  // Don't forget the aContentType ranges from 1..8, while the
  // array is indexed 0..7
  uint32_t permission;
  nsresult rv = mPermissionManager->TestPermission(aCurrentURI, 
                                                   kTypeString[aContentType - 1],
                                                   &permission);
  NS_ENSURE_SUCCESS(rv, rv);

  // If there is nothing on the list, use the default.
  if (!permission) {
    permission = mBehaviorPref[aContentType - 1];
    *aFromPrefs = true;
  }

  // Use the fact that the nsIPermissionManager values map to 
  // the BEHAVIOR_* values above.
  switch (permission) {
  case BEHAVIOR_ACCEPT:
    *aPermission = true;
    break;
  case BEHAVIOR_REJECT:
    *aPermission = false;
    break;

  case BEHAVIOR_NOFOREIGN:
    // Third party checking

    // Need a requesting uri for third party checks to work.
    if (!aFirstURI)
      return NS_OK;

    bool trustedSource = false;
    rv = aFirstURI->SchemeIs("chrome", &trustedSource);
    NS_ENSURE_SUCCESS(rv,rv);
    if (!trustedSource) {
      rv = aFirstURI->SchemeIs("resource", &trustedSource);
      NS_ENSURE_SUCCESS(rv,rv);
    }
    if (trustedSource)
      return NS_OK;

    // compare tails of names checking to see if they have a common domain
    // we do this by comparing the tails of both names where each tail 
    // includes at least one dot
    
    // A more generic method somewhere would be nice

    nsAutoCString currentHost;
    rv = aCurrentURI->GetAsciiHost(currentHost);
    NS_ENSURE_SUCCESS(rv, rv);

    // Search for two dots, starting at the end.
    // If there are no two dots found, ++dot will turn to zero,
    // that will return the entire string.
    int32_t dot = currentHost.RFindChar('.');
    dot = currentHost.RFindChar('.', dot-1);
    ++dot;

    // Get the domain, ie the last part of the host (www.domain.com -> domain.com)
    // This will break on co.uk
    const nsCSubstring &tail =
      Substring(currentHost, dot, currentHost.Length() - dot);

    nsAutoCString firstHost;
    rv = aFirstURI->GetAsciiHost(firstHost);
    NS_ENSURE_SUCCESS(rv, rv);

    // If the tail is longer then the whole firstHost, it will never match
    if (firstHost.Length() < tail.Length()) {
      *aPermission = false;
      return NS_OK;
    }
    
    // Get the last part of the firstUri with the same length as |tail|
    const nsCSubstring &firstTail = 
      Substring(firstHost, firstHost.Length() - tail.Length(), tail.Length());

    // Check that both tails are the same, and that just before the tail in
    // |firstUri| there is a dot. That means both url are in the same domain
    if ((firstHost.Length() > tail.Length() && 
         firstHost.CharAt(firstHost.Length() - tail.Length() - 1) != '.') || 
        !tail.Equals(firstTail)) {
      *aPermission = false;
    }
    break;
  }
  
  return NS_OK;
}

NS_IMETHODIMP
nsContentBlocker::Observe(nsISupports     *aSubject,
                          const char      *aTopic,
                          const PRUnichar *aData)
{
  NS_ASSERTION(!strcmp(NS_PREFBRANCH_PREFCHANGE_TOPIC_ID, aTopic),
               "unexpected topic - we only deal with pref changes!");

  if (mPrefBranchInternal)
    PrefChanged(mPrefBranchInternal, NS_LossyConvertUTF16toASCII(aData).get());
  return NS_OK;
}