On Sun, Jan 25, 2015 at 12:42 PM, Alexander Holler <holler@xxxxxxxxxxxxx> wrote: > Now, after I ended up into flaming a lot (sorry again, but this topic made > me angry for so long and I had to spent too much time to get rid of unwanted > content and answering other peoples question in regard to that topic), I > should offer something more useful. > > So I've written down in some short words, how I think it could be done: > > First offer a syscall named sunlink() (or whatever name) which fails if it > can't overwrite or securely trim the contents of a file before deleting it. > > That could be done like this: > > (1) If it's a SSD or MMC without offering "Secure Trim" fail. > (2) If it's a plain FLASH or conventional harddisk where writing a block > means that block will be overwritten or if it's a SSD or MMC with "Secure > Trim) go on with > (3) Identify the blocks which contain the file contents (should be doable by > using the same mechanisms used to read and write a file) > (4) Mark the file as deleted > (5) Overwrite or securely trim blocks which can be deleted completely > (6) Build new blocks for blocks which can only partly deleted because they > contain information still used by the FS or other files > (7) Instruct the FS to us the new blocks instead of the old ones > (8) Overwrite or securely trim the old blocks which previously contained > partly information of other stuff. > > Afterwards use that new syscall in shred. > > Of course, this is just a totally simplified instruction in regard to how > complicated filesystems have become, but I think there isn't any black magic > involved in offering the user a simple way to really delete files. Or add support for the "s" chattr to major filesystems. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
