-------- Original Message --------
> hello
> I am working on adding a simple encryption to file contents in ext4 driver
> (for learning purposes) I added simple XOR encryption to aio_read and
> aio_write functions and it worked until I faced this problem:
>
> when I open a file in encrypted filesystem using VIM text editor and when I
> try to save it it gives me this error:
>
>>> pointer block id wrong
>>> can not find line 1
>
> and it just corrupts the entire file!
>
> this is my aio_write function:
>
> aio_write_enc(struct kiocb *iocb, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos)
> {
> size_t i;
> ssize_t ret;
> char *data=vmalloc(sizeof(char)*iov->iov_len);
> copy_from_user(data,iov->iov_base,iov->iov_len);
>
> for(i=0;i<iov->iov_len;i++)
> {
> data[i]^=5;
> }
> struct iovec iov_enc= { .iov_base = iov->iov_base, .iov_len =
> iov->iov_len };
>
> copy_to_user(iov_enc.iov_base,data,iov->iov_len);
> ret=ext4_file_write(iocb,&iov_enc,nr_segs,pos);
> vfree(data);
> return ret;
> }
>
> this just changes the data and then calls original function.
>
> is there anything wrong with this function? can anyone help me?
>
>
>
Hi Amir,
I'm not quite sure about what's wrong with your function, but here are
two suggestions I got from the list when I did similar things:
1. wrapfs
2. ecryptfs
I think you should check these two stackable filesystems if you haven't.
Hope this can help a little bit!
Freeman
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