62f2a1c2be
The rationale for this is to have a place to enable hardening features that are either too invasive or that may be speculative/yet proven to be worthwhile for general-purpose kernels.
55 lines
1.5 KiB
Nix
55 lines
1.5 KiB
Nix
# Based on recommendations from:
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# http://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project#Recommended_settings
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# https://wiki.gentoo.org/wiki/Hardened/Hardened_Kernel_Project
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#
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# The base kernel is assumed to be at least 4.9 or whatever the toplevel
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# linux_hardened package expression uses.
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#
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# Dangerous features that can be permanently (for the boot session) disabled at
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# boot via sysctl or kernel cmdline are left enabled here, for improved
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# flexibility.
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{ stdenv }:
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with stdenv.lib;
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''
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GCC_PLUGINS y # Enable gcc plugin options
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DEBUG_KERNEL y
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DEBUG_RODATA y # Make kernel text & rodata read-only
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DEBUG_WX y # A one-time check for W+X mappings at boot; doesn't do anything beyond printing a warning
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# Additional validation of commonly targetted structures
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DEBUG_CREDENTIALS y
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DEBUG_NOTIFIERS y
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DEBUG_LIST y
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HARDENED_USERCOPY y # Bounds check usercopy
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# Wipe on free with page_poison=1
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PAGE_POISONING y
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PAGE_POISONING_NO_SANITY y
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PAGE_POISONING_ZERO y
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# Stricter /dev/mem
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STRICT_DEVMEM y
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IO_STRICT_DEVMEM y
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# Disable various dangerous settings
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ACPI_CUSTOM_METHOD n # Allows writing directly to physical memory
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PROC_KCORE n # Exposes kernel text image layout
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INET_DIAG n # Has been used for heap based attacks in the past
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${optionalString (stdenv.system == "x86_64-linux") ''
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DEFAULT_MMAP_MIN_ADDR 65536 # Prevent allocation of first 64K of memory
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# Reduce attack surface by disabling various emulations
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IA32_EMULATION n
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X86_X32 n
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VMAP_STACK y # Catch kernel stack overflows
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''}
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''
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