/
alias_processor.rb
1229 lines (1036 loc) · 28.6 KB
/
alias_processor.rb
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require 'brakeman/util'
require 'ruby_parser/bm_sexp_processor'
require 'brakeman/processors/lib/processor_helper'
require 'brakeman/processors/lib/safe_call_helper'
require 'brakeman/processors/lib/call_conversion_helper'
#Returns an s-expression with aliases replaced with their value.
#This does not preserve semantics (due to side effects, etc.), but it makes
#processing easier when searching for various things.
class Brakeman::AliasProcessor < Brakeman::SexpProcessor
include Brakeman::ProcessorHelper
include Brakeman::SafeCallHelper
include Brakeman::Util
include Brakeman::CallConversionHelper
attr_reader :result, :tracker
#Returns a new AliasProcessor with an empty environment.
#
#The recommended usage is:
#
# AliasProcessor.new.process_safely src
def initialize tracker = nil, file_name = nil
super()
@env = SexpProcessor::Environment.new
@inside_if = false
@ignore_ifs = nil
@exp_context = []
@current_module = nil
@tracker = tracker #set in subclass as necessary
@helper_method_cache = {}
@helper_method_info = Hash.new({})
@or_depth_limit = (tracker && tracker.options[:branch_limit]) || 5 #arbitrary default
@meth_env = nil
@file_name = file_name
set_env_defaults
end
#This method processes the given Sexp, but copies it first so
#the original argument will not be modified.
#
#_set_env_ should be an instance of SexpProcessor::Environment. If provided,
#it will be used as the starting environment.
#
#This method returns a new Sexp with variables replaced with their values,
#where possible.
def process_safely src, set_env = nil, file_name = nil
@file_name = file_name
@env = set_env || SexpProcessor::Environment.new
@result = src.deep_clone
process @result
@result
end
#Process a Sexp. If the Sexp has a value associated with it in the
#environment, that value will be returned.
def process_default exp
@exp_context.push exp
begin
exp.map! do |e|
if sexp? e and not e.empty?
process e
else
e
end
end
rescue => err
@tracker.error err if @tracker
end
result = replace(exp)
@exp_context.pop
result
end
def replace exp, int = 0
return exp if int > 3
if replacement = env[exp] and not duplicate? replacement
replace(replacement.deep_clone(exp.line), int + 1)
elsif tracker and replacement = tracker.constant_lookup(exp) and not duplicate? replacement
replace(replacement.deep_clone(exp.line), int + 1)
else
exp
end
end
def process_bracket_call exp
r = replace(exp)
if r != exp
return r
end
exp.arglist = process_default(exp.arglist)
r = replace(exp)
if r != exp
return r
end
t = process(exp.target.deep_clone)
# sometimes t[blah] has a match in the env
# but we don't want to actually set the target
# in case the target is big...which is what this
# whole method is trying to avoid
if t != exp.target
e = exp.deep_clone
e.target = t
r = replace(e)
if r != e
return r
end
else
t = nil
end
if hash? t
if v = process_hash_access(t, exp.first_arg)
v.deep_clone(exp.line)
else
case t.node_type
when :params
exp.target = PARAMS_SEXP.deep_clone(exp.target.line)
when :session
exp.target = SESSION_SEXP.deep_clone(exp.target.line)
when :cookies
exp.target = COOKIES_SEXP.deep_clone(exp.target.line)
end
exp
end
elsif array? t
if v = process_array_access(t, exp.args)
v.deep_clone(exp.line)
else
exp
end
elsif t
exp.target = t
exp
else
if exp.target # `self` target is reported as `nil` https://github.com/seattlerb/ruby_parser/issues/250
exp.target = process_default exp.target
end
exp
end
end
ARRAY_CONST = s(:const, :Array)
HASH_CONST = s(:const, :Hash)
RAILS_TEST = s(:call, s(:call, s(:const, :Rails), :env), :test?)
#Process a method call.
def process_call exp
return exp if process_call_defn? exp
target_var = exp.target
target_var &&= target_var.deep_clone
if exp.node_type == :safe_call
exp.node_type = :call
end
if exp.method == :[]
return process_bracket_call exp
else
exp = process_default exp
end
#In case it is replaced with something else
unless call? exp
return exp
end
target = exp.target
method = exp.method
first_arg = exp.first_arg
if method == :send or method == :try
collapse_send_call exp, first_arg
end
if node_type? target, :or and [:+, :-, :*, :/].include? method
res = process_or_simple_operation(exp)
return res if res
elsif target == ARRAY_CONST and method == :new
return Sexp.new(:array, *exp.args)
elsif target == HASH_CONST and method == :new and first_arg.nil? and !node_type?(@exp_context.last, :iter)
return Sexp.new(:hash)
elsif exp == RAILS_TEST
return Sexp.new(:false)
end
#See if it is possible to simplify some basic cases
#of addition/concatenation.
case method
when :+
if array? target and array? first_arg
exp = join_arrays(target, first_arg, exp)
elsif string? first_arg
exp = join_strings(target, first_arg, exp)
elsif number? first_arg
exp = math_op(:+, target, first_arg, exp)
end
when :-, :*, :/
exp = math_op(method, target, first_arg, exp)
when :[]
if array? target
exp = process_array_access(target, exp.args, exp)
elsif hash? target
exp = process_hash_access(target, first_arg, exp)
end
when :merge!, :update
if hash? target and hash? first_arg
target = process_hash_merge! target, first_arg
env[target_var] = target
return target
end
when :merge
if hash? target and hash? first_arg
return process_hash_merge(target, first_arg)
end
when :<<
if string? target and string? first_arg
target.value << first_arg.value
env[target_var] = target
return target
elsif string? target and string_interp? first_arg
exp = Sexp.new(:dstr, target.value + first_arg[1]).concat(first_arg[2..-1])
env[target_var] = exp
elsif string? first_arg and string_interp? target
if string? target.last
target.last.value << first_arg.value
elsif target.last.is_a? String
target.last << first_arg.value
else
target << first_arg
end
env[target_var] = target
return first_arg
elsif array? target
target << first_arg
env[target_var] = target
return target
else
target = find_push_target(target_var)
env[target] = exp unless target.nil? # Happens in TemplateAliasProcessor
end
when :first
if array? target and first_arg.nil? and sexp? target[1]
exp = target[1]
end
when :freeze
unless target.nil?
exp = target
end
when :join
if array? target and target.length > 2 and (string? first_arg or first_arg.nil?)
exp = process_array_join(target, first_arg)
end
end
exp
end
# Painful conversion of Array#join into string interpolation
def process_array_join array, join_str
result = s()
join_value = if string? join_str
join_str.value
else
nil
end
array[1..-2].each do |e|
result << join_item(e, join_value)
end
result << join_item(array.last, nil)
# Combine the strings at the beginning because that's what RubyParser does
combined_first = ""
result.each do |e|
if string? e
combined_first << e.value
elsif e.is_a? String
combined_first << e
else
break
end
end
# Remove the strings at the beginning
result.reject! do |e|
if e.is_a? String or string? e
true
else
break
end
end
result.unshift combined_first
# Have to fix up strings that follow interpolation
result.reduce(s(:dstr)) do |memo, e|
if string? e and node_type? memo.last, :evstr
e.value = "#{join_value}#{e.value}"
elsif join_value and node_type? memo.last, :evstr and node_type? e, :evstr
memo << s(:str, join_value)
end
memo << e
end
end
def join_item item, join_value
if item.is_a? String
"#{item}#{join_value}"
elsif string? item or symbol? item or number? item
s(:str, "#{item.value}#{join_value}")
else
s(:evstr, item)
end
end
def process_iter exp
@exp_context.push exp
exp[1] = process exp.block_call
if array_detect_all_literals? exp[1]
return safe_literal(exp.line)
end
@exp_context.pop
env.scope do
call = exp.block_call
block_args = exp.block_args
if call? call and [:each, :map].include? call.method and all_literals? call.target and block_args.length == 2 and block_args.last.is_a? Symbol
# Iterating over an array of all literal values
local = Sexp.new(:lvar, block_args.last)
env.current[local] = safe_literal(exp.line)
else
block_args.each do |e|
#Force block arg(s) to be local
if node_type? e, :lasgn
env.current[Sexp.new(:lvar, e.lhs)] = Sexp.new(:lvar, e.lhs)
elsif node_type? e, :kwarg
env.current[Sexp.new(:lvar, e[1])] = e[2]
elsif node_type? e, :masgn, :shadow
e[1..-1].each do |var|
local = Sexp.new(:lvar, var)
env.current[local] = local
end
elsif e.is_a? Symbol
local = Sexp.new(:lvar, e)
env.current[local] = local
else
raise "Unexpected value in block args: #{e.inspect}"
end
end
end
block = exp.block
if block? block
process_all! block
else
exp[3] = process block
end
end
exp
end
#Process a new scope.
def process_scope exp
env.scope do
process exp.block
end
exp
end
#Start new scope for block.
def process_block exp
env.scope do
process_default exp
end
end
#Process a method definition.
def process_defn exp
meth_env do
exp.body = process_all! exp.body
end
exp
end
def meth_env
begin
env.scope do
set_env_defaults
@meth_env = env.current
yield
end
ensure
@meth_env = nil
end
end
#Process a method definition on self.
def process_defs exp
env.scope do
set_env_defaults
exp.body = process_all! exp.body
end
exp
end
# Handles x = y = z = 1
def get_rhs exp
if node_type? exp, :lasgn, :iasgn, :gasgn, :attrasgn, :safe_attrasgn, :cvdecl, :cdecl
get_rhs(exp.rhs)
else
exp
end
end
#Local assignment
# x = 1
def process_lasgn exp
self_assign = self_assign?(exp.lhs, exp.rhs)
exp.rhs = process exp.rhs if sexp? exp.rhs
return exp if exp.rhs.nil?
local = Sexp.new(:lvar, exp.lhs).line(exp.line || -2)
if self_assign
# Skip branching
env[local] = get_rhs(exp)
else
set_value local, get_rhs(exp)
end
exp
end
#Instance variable assignment
# @x = 1
def process_iasgn exp
self_assign = self_assign?(exp.lhs, exp.rhs)
exp.rhs = process exp.rhs
ivar = Sexp.new(:ivar, exp.lhs).line(exp.line)
if self_assign
if env[ivar].nil? and @meth_env
@meth_env[ivar] = get_rhs(exp)
else
env[ivar] = get_rhs(exp)
end
else
set_value ivar, get_rhs(exp)
end
exp
end
#Global assignment
# $x = 1
def process_gasgn exp
match = Sexp.new(:gvar, exp.lhs)
exp.rhs = process(exp.rhs)
value = get_rhs(exp)
if value
value.line = exp.line
set_value match, value
end
exp
end
#Class variable assignment
# @@x = 1
def process_cvdecl exp
match = Sexp.new(:cvar, exp.lhs)
exp.rhs = process(exp.rhs)
value = get_rhs(exp)
set_value match, value
exp
end
#'Attribute' assignment
# x.y = 1
#or
# x[:y] = 1
def process_attrasgn exp
tar_variable = exp.target
target = process(exp.target)
method = exp.method
index_arg = exp.first_arg
value_arg = exp.second_arg
if method == :[]=
index = exp.first_arg = process(index_arg)
value = exp.second_arg = process(value_arg)
match = Sexp.new(:call, target, :[], index)
set_value match, value
if hash? target
env[tar_variable] = hash_insert target.deep_clone, index, value
end
unless node_type? target, :hash
exp.target = target
end
elsif method.to_s[-1,1] == "="
exp.first_arg = process(index_arg)
value = get_rhs(exp)
#This is what we'll replace with the value
match = Sexp.new(:call, target, method.to_s[0..-2].to_sym)
set_value match, value
exp.target = target
else
raise "Unrecognized assignment: #{exp}"
end
exp
end
# Multiple/parallel assignment:
#
# x, y = z, w
def process_masgn exp
exp[2] = process exp[2] if sexp? exp[2]
if node_type? exp[2], :to_ary and array? exp[2][1]
exp[2] = exp[2][1]
end
unless array? exp[1] and array? exp[2] and exp[1].length == exp[2].length
return process_default(exp)
end
vars = exp[1].dup
vals = exp[2].dup
vars.shift
vals.shift
# Call each assignment as if it is normal
vars.each_with_index do |var, i|
val = vals[i]
if val
# This happens with nested destructuring like
# x, (a, b) = blah
if node_type? var, :masgn
# Need to add value to masgn exp
m = var.dup
m[2] = s(:to_ary, val)
process_masgn m
else
assign = var.dup
assign.rhs = val
process assign
end
end
end
exp
end
#Merge values into hash when processing
#
# h.merge! :something => "value"
def process_hash_merge! hash, args
hash = hash.deep_clone
hash_iterate args do |key, replacement|
hash_insert hash, key, replacement
match = Sexp.new(:call, hash, :[], key)
env[match] = replacement
end
hash
end
#Return a new hash Sexp with the given values merged into it.
#
#+args+ should be a hash Sexp as well.
def process_hash_merge hash, args
hash = hash.deep_clone
hash_iterate args do |key, replacement|
hash_insert hash, key, replacement
end
hash
end
#Assignments like this
# x[:y] ||= 1
def process_op_asgn1 exp
target_var = exp[1]
target_var &&= target_var.deep_clone
target = exp[1] = process(exp[1])
index = exp[2][1] = process(exp[2][1])
value = exp[4] = process(exp[4])
match = Sexp.new(:call, target, :[], index)
if exp[3] == :"||"
unless env[match]
if request_value? target
env[match] = match.combine(value)
else
env[match] = value
end
end
else
new_value = process s(:call, s(:call, target_var, :[], index), exp[3], value)
env[match] = new_value
end
exp
end
#Assignments like this
# x.y ||= 1
def process_op_asgn2 exp
return process_default(exp) if exp[3] != :"||"
target = exp[1] = process(exp[1])
value = exp[4] = process(exp[4])
method = exp[2]
match = Sexp.new(:call, target, method.to_s[0..-2].to_sym)
unless env[match]
env[match] = value
end
exp
end
#This is the right hand side value of a multiple assignment,
#like `x = y, z`
def process_svalue exp
exp.value
end
#Constant assignments like
# BIG_CONSTANT = 234810983
def process_cdecl exp
if sexp? exp.rhs
exp.rhs = process exp.rhs
end
if @tracker
@tracker.add_constant exp.lhs,
exp.rhs,
:file => current_file_name,
:module => @current_module,
:class => @current_class,
:method => @current_method
end
if exp.lhs.is_a? Symbol
match = Sexp.new(:const, exp.lhs)
else
match = exp.lhs
end
env[match] = get_rhs(exp)
exp
end
# Check if exp is a call to Array#include? on an array literal
# that contains all literal values. For example:
#
# [1, 2, "a"].include? x
#
def array_include_all_literals? exp
call? exp and
exp.method == :include? and
all_literals? exp.target
end
def array_detect_all_literals? exp
call? exp and
[:detect, :find].include? exp.method and
exp.first_arg.nil? and
all_literals? exp.target
end
#Sets @inside_if = true
def process_if exp
if @ignore_ifs.nil?
@ignore_ifs = @tracker && @tracker.options[:ignore_ifs]
end
condition = exp.condition = process exp.condition
#Check if a branch is obviously going to be taken
if true? condition
no_branch = true
exps = [exp.then_clause, nil]
elsif false? condition
no_branch = true
exps = [nil, exp.else_clause]
else
no_branch = false
exps = [exp.then_clause, exp.else_clause]
end
if @ignore_ifs or no_branch
exps.each_with_index do |branch, i|
exp[2 + i] = process_if_branch branch
end
else
was_inside = @inside_if
@inside_if = true
branch_scopes = []
exps.each_with_index do |branch, i|
scope do
@branch_env = env.current
branch_index = 2 + i # s(:if, condition, then_branch, else_branch)
if i == 0 and array_include_all_literals? condition
# If the condition is ["a", "b"].include? x
# set x to "a" inside the true branch
var = condition.first_arg
previous_value = env.current[var]
env.current[var] = safe_literal(var.line)
exp[branch_index] = process_if_branch branch
env.current[var] = previous_value
elsif i == 1 and array_include_all_literals? condition and early_return? branch
var = condition.first_arg
env.current[var] = safe_literal(var.line)
exp[branch_index] = process_if_branch branch
else
exp[branch_index] = process_if_branch branch
end
branch_scopes << env.current
@branch_env = nil
end
end
@inside_if = was_inside
branch_scopes.each do |s|
merge_if_branch s
end
end
exp
end
def early_return? exp
return true if node_type? exp, :return
return true if call? exp and [:fail, :raise].include? exp.method
if node_type? exp, :block, :rlist
node_type? exp.last, :return or
(call? exp and [:fail, :raise].include? exp.method)
else
false
end
end
def simple_when? exp
node_type? exp[1], :array and
not node_type? exp[1][1], :splat, :array and
(exp[1].length == 2 or
exp[1].all? { |e| e.is_a? Symbol or node_type? e, :lit, :str })
end
def process_case exp
if @ignore_ifs.nil?
@ignore_ifs = @tracker && @tracker.options[:ignore_ifs]
end
if @ignore_ifs
process_default exp
return exp
end
branch_scopes = []
was_inside = @inside_if
@inside_if = true
exp[1] = process exp[1] if exp[1]
case_value = if node_type? exp[1], :lvar, :ivar, :call
exp[1].deep_clone
end
exp.each_sexp do |e|
if node_type? e, :when
scope do
@branch_env = env.current
# set value of case var if possible
if case_value and simple_when? e
@branch_env[case_value] = e[1][1]
end
# when blocks aren't blocks, they are lists of expressions
process_default e
branch_scopes << env.current
@branch_env = nil
end
end
end
# else clause
if sexp? exp.last
scope do
@branch_env = env.current
process_default exp[-1]
branch_scopes << env.current
@branch_env = nil
end
end
@inside_if = was_inside
branch_scopes.each do |s|
merge_if_branch s
end
exp
end
def process_if_branch exp
if sexp? exp
if block? exp
process_default exp
else
process exp
end
end
end
def merge_if_branch branch_env
branch_env.each do |k, v|
next if v.nil?
current_val = env[k]
if current_val
unless same_value?(current_val, v)
if too_deep? current_val
# Give up branching, start over with latest value
env[k] = v
else
env[k] = current_val.combine(v, k.line)
end
end
else
env[k] = v
end
end
end
def too_deep? exp
@or_depth_limit >= 0 and
node_type? exp, :or and
exp.or_depth and
exp.or_depth >= @or_depth_limit
end
# Change x.send(:y, 1) to x.y(1)
def collapse_send_call exp, first_arg
# Handle try(&:id)
if node_type? first_arg, :block_pass
first_arg = first_arg[1]
end
return unless symbol? first_arg or string? first_arg
exp.method = first_arg.value.to_sym
args = exp.args
exp.pop # remove last arg
if args.length > 1
exp.arglist = args[1..-1]
end
end
#Returns a new SexpProcessor::Environment containing only instance variables.
#This is useful, for example, when processing views.
def only_ivars include_request_vars = false, lenv = nil
lenv ||= env
res = SexpProcessor::Environment.new
if include_request_vars
lenv.all.each do |k, v|
#TODO Why would this have nil values?
if (k.node_type == :ivar or request_value? k) and not v.nil?
res[k] = v.dup
end
end
else
lenv.all.each do |k, v|
#TODO Why would this have nil values?
if k.node_type == :ivar and not v.nil?
res[k] = v.dup
end
end
end
res
end
def only_request_vars
res = SexpProcessor::Environment.new
env.all.each do |k, v|
if request_value? k and not v.nil?
res[k] = v.dup
end
end
res
end
def get_call_value call
method_name = call.method
#Look for helper methods and see if we can get a return value
if found_method = find_method(method_name, @current_class)
helper = found_method[:method]
if sexp? helper
value = process_helper_method helper, call.args
value.line(call.line)
return value
else
raise "Unexpected value for method: #{found_method}"
end
else
call
end
end
def process_helper_method method_exp, args
method_name = method_exp.method_name
Brakeman.debug "Processing method #{method_name}"
info = @helper_method_info[method_name]
#If method uses instance variables, then include those and request
#variables (params, etc) in the method environment. Otherwise,
#only include request variables.
if info[:uses_ivars]
meth_env = only_ivars(:include_request_vars)
else
meth_env = only_request_vars
end
#Add arguments to method environment
assign_args method_exp, args, meth_env
#Find return values if method does not depend on environment/args
values = @helper_method_cache[method_name]
unless values
#Serialize environment for cache key
meth_values = meth_env.instance_variable_get(:@env).to_a
meth_values.sort!
meth_values = meth_values.to_s
digest = Digest::SHA1.new.update(meth_values << method_name.to_s).to_s.to_sym
values = @helper_method_cache[digest]
end
if values
#Use values from cache
values[:ivar_values].each do |var, val|
env[var] = val
end