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sodium.cr
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Sodium::SecureBuffer is now a Crypto::Secret

master
Didactic Drunk 2021-06-14 17:02:37 -07:00
parent cd0ce1ccdb
commit fca40d7764
4 changed files with 56 additions and 151 deletions
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4
shard.yml
View File

@ -10,6 +10,10 @@ targets:
main: examples/blake2b_hash.cr
pwhash_selector:
main: examples/pwhash_selector.cr
dependencies:
crypto-secret:
github: didactic-drunk/crypto-secret.cr
branch: main
libraries:
libsodium: ">= 1.0.18"
license: MIT

43
spec/sodium/secure_buffer_spec.cr
View File

@ -7,8 +7,10 @@ end
describe Sodium::SecureBuffer do
it "allocates empty" do
buf = Sodium::SecureBuffer.new 5
buf.to_slice.each do |b|
b.should eq 0xdb_u8
buf.readonly do |slice|
slice.each do |b|
b.should eq 0xdb_u8
end
end
buf.noaccess
@ -17,18 +19,22 @@ describe Sodium::SecureBuffer do
end
it "allocates random" do
buf = Sodium::SecureBuffer.random 5
buf.to_slice.bytesize.should eq 5
buf.wipe
buf1 = Sodium::SecureBuffer.random 5
buf2 = Sodium::SecureBuffer.random 5
(buf1 == buf2).should be_false
buf1.wipe
end
it "copies and erases" do
bytes = Bytes.new(5) { 1_u8 }
buf = Sodium::SecureBuffer.new bytes, erase: true
buf.to_slice.bytesize.should eq 5
buf.to_slice.each do |b|
b.should eq 1_u8
buf.readonly do |slice|
slice.bytesize.should eq 5
slice.each do |b|
b.should eq 1_u8
end
end
bytes.to_slice.each do |b|
@ -37,16 +43,21 @@ describe Sodium::SecureBuffer do
end
it "dups without crashing" do
buf = Sodium::SecureBuffer.new 5
buf.readwrite
buf1 = Sodium::SecureBuffer.new 5
buf1.noaccess
buf2 = buf.dup
buf2.@state.should eq Sodium::SecureBuffer::State::Readwrite
buf2 = buf1.dup
buf2.@state.should eq Sodium::SecureBuffer::State::Noaccess
buf[0] = 1_u8
buf.to_slice.hexstring.should_not eq buf2.to_slice.hexstring
buf2[0] = 1_u8
buf.to_slice.hexstring.should eq buf2.to_slice.hexstring
buf1.readwrite do |slice|
slice[0] = 1_u8
end
buf1.hexstring.should_not eq buf2.hexstring
buf2.readwrite do |slice|
slice[0] = 1_u8
end
buf1.hexstring.should eq buf2.hexstring
end
it "transitions correctly" do

8
src/sodium/kdf.cr
View File

@ -79,9 +79,11 @@ module Sodium
end
subkey = SecureBuffer.new subkey_size
@sbuf.readonly do
if (ret = LibSodium.crypto_kdf_derive_from_key(subkey, subkey.bytesize, subkey_id, context, self.to_slice)) != 0
raise Sodium::Error.new("crypto_kdf_derive_from_key returned #{ret} (subkey size is probably out of range)")
subkey.readwrite do |sub_slice|
@sbuf.readonly do
if (ret = LibSodium.crypto_kdf_derive_from_key(sub_slice, sub_slice.bytesize, subkey_id, context, self.to_slice)) != 0
raise Sodium::Error.new("crypto_kdf_derive_from_key returned #{ret} (subkey size is probably out of range)")
end
end
end

152
src/sodium/secure_buffer.cr
View File

@ -1,5 +1,6 @@
require "./lib_sodium"
require "./wipe"
require "crypto-secret/stateful"
module Sodium
# Allocate guarded memory using [sodium_malloc](https://libsodium.gitbook.io/doc/memory_management)
@ -7,44 +8,17 @@ module Sodium
# #initialize returns readonly or readwrite for thread safety
# When state changes are required (such as using #noaccess) and the buffer is accessed from multiple threads wrap each #readonly/#readwrite block in a lock.
class SecureBuffer
class Error < Sodium::Error
class KeyWiped < Error
end
include Crypto::Secret::Stateful
class InvalidStateTransition < Error
end
# @state = State::Readwrite
# Check RLIMIT_MEMLOCK if you receive this
class OutOfMemory < Error
end
end
enum State
Cloning
Wiped
Noaccess
Readonly
Readwrite
end
@state = State::Readwrite
getter bytesize
delegate :+, :[], :[]=, :hexstring, to: to_slice
getter bytesize : Int32
def initialize(@bytesize : Int32)
@ptr = LibSodium.sodium_malloc @bytesize
raise Error::OutOfMemory.new if @ptr.null?
end
# Returns a **readonly** random SecureBuffer.
def self.random(size)
buf = new(size)
Random::Secure.random_bytes buf.to_slice
buf.readonly
end
# Copies bytes to a **readonly** SecureBuffer.
# Optionally erases bytes after copying if erase is set
# Returns a **readonly** SecureBuffer.
@ -61,30 +35,16 @@ module Sodium
initialize sbuf.bytesize
# Maybe not thread safe
sbuf.readonly do
sbuf.to_slice.copy_to self.to_slice
sbuf.readonly do |s1|
self.to_slice do |s2|
s1.copy_to s2.to_slice
end
end
@state = State::Cloning
set_state sbuf.@state
end
# WARNING: Not thread safe
def wipe
return if @state == State::Wiped
readwrite
Sodium.memzero self.to_slice
@state = State::Wiped
noaccess!
end
# WARNING: Not thread safe
def wipe
yield
ensure
wipe
end
# :nodoc:
def finalize
LibSodium.sodium_free @ptr
@ -103,6 +63,11 @@ module Sodium
Slice(UInt8).new @ptr, @bytesize
end
def to_slice(& : Bytes -> Nil)
yield Bytes.new @ptr, @bytesize
end
# :nodoc:
def to_unsafe
@ptr
end
@ -112,98 +77,21 @@ module Sodium
self.class.new self
end
# Temporarily make buffer readonly within the block returning to the prior state on exit.
# WARNING: Not thread safe unless this object is readonly or readwrite
def readonly
with_state State::Readonly do
yield
end
end
# Temporarily make buffer readwrite within the block returning to the prior state on exit.
# WARNING: Not thread safe unless this object is **readwrite**
def readwrite
with_state State::Readwrite do
yield
end
end
# Makes a region allocated using sodium_malloc() or sodium_allocarray() inaccessible. It cannot be read or written, but the data are preserved.
# WARNING: Not thread safe
def noaccess
raise Error::KeyWiped.new if @state == State::Wiped
noaccess!
@state = State::Noaccess
self
end
# Also used by #wipe
private def noaccess!
if LibSodium.sodium_mprotect_noaccess(@ptr) != 0
raise "sodium_mprotect_noaccess"
end
self
end
# Marks a region allocated using sodium_malloc() or sodium_allocarray() as read-only.
# WARNING: Not thread safe
def readonly
raise Error::KeyWiped.new if @state == State::Wiped
if LibSodium.sodium_mprotect_readonly(@ptr) != 0
raise "sodium_mprotect_readonly"
end
@state = State::Readonly
self
end
# Marks a region allocated using sodium_malloc() or sodium_allocarray() as readable and writable, after having been protected using sodium_mprotect_readonly() or sodium_mprotect_noaccess().
# WARNING: Not thread safe
def readwrite
raise Error::KeyWiped.new if @state == State::Wiped
protected def readwrite_impl : Nil
if LibSodium.sodium_mprotect_readwrite(@ptr) != 0
raise "sodium_mprotect_readwrite"
end
@state = State::Readwrite
self
end
# Timing safe memory compare.
def ==(other : self)
Sodium.memcmp self.to_slice, other.to_slice
end
# Timing safe memory compare.
def ==(other : Bytes)
Sodium.memcmp self.to_slice, other
end
# WARNING: Not thread safe
private def set_state(new_state : State)
return if @state == new_state
case new_state
when State::Readwrite; readwrite
when State::Readonly ; readonly
when State::Noaccess ; noaccess
when State::Wiped ; raise Error::InvalidStateTransition.new
else
raise "unknown state #{new_state}"
protected def readonly_impl : Nil
if LibSodium.sodium_mprotect_readonly(@ptr) != 0
raise "sodium_mprotect_readonly"
end
end
# WARNING: Only thread safe when current state >= requested state
private def with_state(new_state : State)
old_state = @state
# Only change when new_state needs more access than @state.
if old_state >= new_state
yield
else
begin
set_state new_state
yield
ensure
set_state old_state
end
protected def noaccess_impl : Nil
if LibSodium.sodium_mprotect_noaccess(@ptr) != 0
raise "sodium_mprotect_noaccess"
end
end
end