Modify FS Root in an Unrevertable Way

• Overwrite functions. Bypass Method: Mentioned earlier.
• Make a local function performing all the changes and overwrite the global one to call the local one. Bypass Method: Append "../" to the start of the file name string.
• Load it into executed programs as an environment variable. Bypass Method: Overwrite and then run shell.

path = string.find(newroot,fs.combine(newroot,path)) and fs.combine(newroot,path) or newroot

Creator, on 16 June 2015 - 09:32 PM said:

Well, do this:

path = string.find(newroot,fs.combine(newroot,path)) and fs.combine(newroot,path) or newroot

That way you'll be sure they aint bypassing anything.

-- example of fs.open
local oldOpen = fs.open
local combine = fs.combine
newroot = "this/is/a/file/path/to/the/new/root"

fs.open = function(path,...)
  -- you would likely want checks here to make sure path is a string.
  path = combine(newroot,path)
  local s,e = path:find(newroot)
  path = e and e<=#newroot and path or combine(newroot,path)
  return oldOpen(path,...)
end

local oldOpen = fs.open
local combine = fs.combine
local lType = type
local err = error
newroot = "this/is/a/file/path/to/the/new/root"

fs.open = function(path,...)
  if lType(path) == "string" then
	path = combine("/",path) --# gets rid of all the ".."'s
	path = combine(newroot,path)
	return oldOpen(path,...)
  else
	err("Expected String, String")
  end
end

Creator, on 16 June 2015 - 09:55 PM said:

path could be "../i/am/at/the/real/root" – these ".." make it go up a dir.

CrazyPyroEagle, on 16 June 2015 - 11:28 PM said:

I mentioned that solution in the first post and said that it could be bypassed using ".."

Maybe I could remove all preceding ".." components or error if they're there…

MKlegoman357, on 16 June 2015 - 11:56 PM said:

Like valithor already mentioned, fs.combine deals with "..", a single fs.combine( rootPath, userGivenPath ) is enough.

fs.combine("this/is/the/new/root","../../../../hi")

CrazyPyroEagle, on 17 June 2015 - 01:02 PM said:

Wow thank you for the great solution, I'll try it in a minute…

Edit: Shouldn't I also overwrite _G.fs[func] to prevent bypassing?

local newpath = fs.combine(root, fs.combine("/", path))

fs.combine("", ",,/path") --> ",,/path" # for some reason the forums doesn't let me use dots, so pretend that commas are dots..

local oldOpen = fs.open
local combine = fs.combine
local lType = type
local err = error
newroot = "this/is/a/file/path/to/the/new/root"

fs.open = function(path,...)
  if lType(path) == "string" then
		path = combine("/",path):gsub("%.%./?","") --# gets rid of all the ".."'s
		path = combine(newroot,path)
		return oldOpen(path,...)
  else
		err("Expected String, String")
  end
end