narayana/conversations-classic
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prevent receiving (as share with target) file URIs

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as Element (Matrix client) demonstrated again file URIs are unnecessarily dangerous. On Android 7+ there is no good reason to process them anymore
This commit is contained in:
Daniel Gultsch 2024-03-01 14:39:54 +01:00
parent 2ac4efa259
commit 86b733e159
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GPG key ID: F43D18AD2A0982C2
2 changed files with 24 additions and 18 deletions
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38
src/main/java/eu/siacs/conversations/persistance/FileBackend.java
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@ -370,29 +370,35 @@ public class FileBackend {
}
}
public static boolean weOwnFile(final Uri uri) {
if (uri == null || !ContentResolver.SCHEME_FILE.equals(uri.getScheme())) {
return false;
} else {
return weOwnFileLollipop(uri);
public static boolean dangerousFile(final Uri uri) {
if (uri == null || Strings.isNullOrEmpty(uri.getScheme())) {
return true;
}
if (ContentResolver.SCHEME_FILE.equals(uri.getScheme())) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
// On Android 7 (and apps that target 7) it is now longer possible to share files
// with a file scheme. By now you should probably not be running apps that target
// anything less than 7 any more
return true;
} else {
return isFileOwnedByProcess(uri);
}
}
return false;
}
private static boolean weOwnFileLollipop(final Uri uri) {
private static boolean isFileOwnedByProcess(final Uri uri) {
final String path = uri.getPath();
if (path == null) {
return false;
return true;
}
try {
File file = new File(path);
FileDescriptor fd =
ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY)
.getFileDescriptor();
StructStat st = Os.fstat(fd);
try (final var pfd =
ParcelFileDescriptor.open(new File(path), ParcelFileDescriptor.MODE_READ_ONLY)) {
final FileDescriptor fd = pfd.getFileDescriptor();
final StructStat st = Os.fstat(fd);
return st.st_uid == android.os.Process.myUid();
} catch (FileNotFoundException e) {
return false;
} catch (Exception e) {
} catch (final Exception e) {
// when in doubt. better safe than sorry
return true;
}
}

4
src/main/java/eu/siacs/conversations/ui/ConversationFragment.java
View file

@ -2619,10 +2619,10 @@ public class ConversationFragment extends XmppFragment
final Iterator<Uri> iterator = uris.iterator();
while (iterator.hasNext()) {
final Uri uri = iterator.next();
if (FileBackend.weOwnFile(uri)) {
if (FileBackend.dangerousFile(uri)) {
iterator.remove();
Toast.makeText(
getActivity(),
requireActivity(),
R.string.security_violation_not_attaching_file,
Toast.LENGTH_SHORT)
.show();