nim-wiki/Security.asciidoc

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== Security
:toc: right
NOTE: The page is Work In Progress
This page documents security aspects of Nim and best practices.
Security features in the language:
* No pointer arithmetic
* http://nim-lang.org/docs/manual.html#taint-mode[Taint mode]
* The http://nim-lang.org/docs/manual.html#effect-system[Effect system] can be used for security
* Nim attempts to generate C code that does not rely on unsecure function/patterns (e.g. unchecked strcpy)
* The language encourage using immutable and const values
* Type conversions are memory-safe
* Low-level memory access allows mlock (TODO: add example) and memory wipe (TODO: add example)
* http://nim-lang.org/docs/manual.html#types-memory-regions[Memory regions] TODO
=== Compiling with GCC on Linux
Nim attempts to generate C code that does not rely on unsecure function/patterns.
As such, some of the options listed below might be less useful than when building pure-C applications.
All the following options enabled together:
[source,bash]
----
--passC:"-fPIE -Wformat -Wformat-security -D_FORTIFY_SOURCE=2 -O1 -fstack-protector-all" --passL:"-fPIE -pie -z relro -z now"
----
==== Stack protector
Terminate execution when the stack is being overwritten
[source,bash]
----
nim c --passC:"-fstack-protector-all"
----
==== Protect againt fixed-size buffer overflow
[source,bash]
----
nim c --passC:"-D_FORTIFY_SOURCE=2 -O1"
----
==== Warn on unsecure prinf usage
[source,bash]
----
nim c --passC:"-Wformat -Wformat-security"
----
==== Position independent executable
Enable ASLR
[source,bash]
----
nim c --passC:"-fPIE" --passL:"-fPIE -pie"
----
==== Full RELRO
Resolve dynamic symbols at startup and flag the GOT as read-only.
[source,bash]
----
nim c --passL:"-z relro -z now"
----
=== Resources
https://wiki.debian.org/Hardening