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util/human/io.lua @ 12180:53e0ae770917
util.xml: Do not allow doctypes, comments or processing instructions
Yes. This is as bad as it sounds. CVE pending.
In Prosody itself, this only affects mod_websocket, which uses util.xml
to parse the <open/> frame, thus allowing unauthenticated remote DoS
using Billion Laughs. However, third-party modules using util.xml may
also be affected by this.
This commit installs handlers which disallow the use of doctype
declarations and processing instructions without any escape hatch. It,
by default, also introduces such a handler for comments, however, there
is a way to enable comments nontheless.
This is because util.xml is used to parse human-facing data, where
comments are generally a desirable feature, and also because comments
are generally harmless.
author | Jonas Schäfer <jonas@wielicki.name> |
---|---|
date | Mon, 10 Jan 2022 18:23:54 +0100 |
parent | 11897:e84ea5b58b29 |
child | 12573:0f4feaf9ca64 |
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local array = require "util.array"; local utf8 = rawget(_G, "utf8") or require"util.encodings".utf8; local len = utf8.len or function(s) local _, count = s:gsub("[%z\001-\127\194-\253][\128-\191]*", ""); return count; end; local function getchar(n) local stty_ret = os.execute("stty raw -echo 2>/dev/null"); local ok, char; if stty_ret == true or stty_ret == 0 then ok, char = pcall(io.read, n or 1); os.execute("stty sane"); else ok, char = pcall(io.read, "*l"); if ok then char = char:sub(1, n or 1); end end if ok then return char; end end local function getline() local ok, line = pcall(io.read, "*l"); if ok then return line; end end local function getpass() local stty_ret, _, status_code = os.execute("stty -echo 2>/dev/null"); if status_code then -- COMPAT w/ Lua 5.1 stty_ret = status_code; end if stty_ret ~= 0 then io.write("\027[08m"); -- ANSI 'hidden' text attribute end local ok, pass = pcall(io.read, "*l"); if stty_ret == 0 then os.execute("stty sane"); else io.write("\027[00m"); end io.write("\n"); if ok then return pass; end end local function show_yesno(prompt) io.write(prompt, " "); local choice = getchar():lower(); io.write("\n"); if not choice:match("%a") then choice = prompt:match("%[.-(%U).-%]$"); if not choice then return nil; end end return (choice == "y"); end local function read_password() local password; while true do io.write("Enter new password: "); password = getpass(); if not password then print("No password - cancelled"); return; end io.write("Retype new password: "); if getpass() ~= password then if not show_yesno [=[Passwords did not match, try again? [Y/n]]=] then return; end else break; end end return password; end local function show_prompt(prompt) io.write(prompt, " "); local line = getline(); line = line and line:gsub("\n$",""); return (line and #line > 0) and line or nil; end local function printf(fmt, ...) print(fmt:format(...)); end local function padright(s, width) return s..string.rep(" ", width-len(s)); end local function padleft(s, width) return string.rep(" ", width-len(s))..s; end local pat = "[%z\001-\127\194-\253][\128-\191]*"; local function utf8_cut(s, pos) return s:match("^"..pat:rep(pos)) or s; end if utf8.len and utf8.offset then function utf8_cut(s, pos) return s:sub(1, utf8.offset(s, pos+1)-1); end end local function ellipsis(s, width) if len(s) <= width then return s; end if width == 1 then return "…"; end return utf8_cut(s, width - 1) .. "…"; end local function new_table(col_specs, max_width) max_width = max_width or tonumber(os.getenv("COLUMNS")) or 80; local separator = " | "; local widths = {}; local total_width = max_width - #separator * (#col_specs-1); local free_width = total_width; -- Calculate width of fixed-size columns for i = 1, #col_specs do local width = col_specs[i].width or "0"; if not(type(width) == "string" and width:sub(-1) == "%") then local title = col_specs[i].title; width = math.max(tonumber(width), title and (#title+1) or 0); widths[i] = width; free_width = free_width - width; if i > 1 then free_width = free_width - #separator; end end end -- Calculate width of %-based columns for i = 1, #col_specs do if not widths[i] then local pc_width = tonumber((col_specs[i].width:gsub("%%$", ""))); widths[i] = math.floor(free_width*(pc_width/100)); end end return function (row) local titles; if not row then titles, row = true, array.pluck(col_specs, "title", ""); end local output = {}; for i, column in ipairs(col_specs) do local width = widths[i]; local v = row[not titles and column.key or i]; if not titles and column.mapper then v = column.mapper(v, row); end if v == nil then v = column.default or ""; else v = tostring(v); end if len(v) < width then if column.align == "right" then v = padleft(v, width); else v = padright(v, width); end elseif len(v) > width then v = ellipsis(v, width); end table.insert(output, v); end return table.concat(output, separator); end; end return { getchar = getchar; getline = getline; getpass = getpass; show_yesno = show_yesno; read_password = read_password; show_prompt = show_prompt; printf = printf; padleft = padleft; padright = padright; ellipsis = ellipsis; table = new_table; };