InferenciumThis documentation contains instructions to use GrapheneOS hardened_malloc memory allocator as the system’s default memory allocator. These instructions apply to both musl and glibc C libraries on Unix-based and Unix-like systems. hardened_malloc can also be used per-application and/or per-user, in which case root permissions are not required; this documentation focuses on system-wide usage of hardened_malloc, assumes root privileges, and assumes the compiled library will be located in a path readable by all users of the system.
For the complete hardened_malloc documentation, visit its official documentation.
Add vm.max_map_count = 1048576 to /etc/sysctl.conf
to accommodate hardened_malloc’s large amount of guard pages.
$ git clone https://github.com/GrapheneOS/hardened_malloc.git
$ cd hardened_malloc/
$ make <arguments>
CONFIG_N_ARENA=n can be adjusted to increase parallel
performance at the expense of memory usage, or decrease memory usage at the
expense of parallel performance, where n is an integer. Higher values
prefer parallel performance, lower values prefer lower memory usage. The number
of arenas has no impact on the security properties of hardened_malloc.
For extra security, CONFIG_SEAL_METADATA=true can be used in
order to control whether Memory Protection Keys are used to disable access to
all writable allocator state outside of the memory allocator code. It’s
currently disabled by default due to a significant performance cost for this use
case on current generation hardware. Whether or not this feature is enabled, the
metadata is all contained within an isolated memory region with high entropy
random guard regions around it.
For low-memory systems, VARIANT=light can be used to compile the
light variant of hardened_malloc, which sacrifices some security for much less
memory usage.
For all compile-time options, see the configuration section of hardened_malloc’s extensive official documentation.
# cp out/libhardened_malloc.so <target path>
musl-based systems: Add export LD_PRELOAD="<hardened_malloc path>"
to /etc/environment
glibc-based systems: Add <hardened_malloc path> to /etc/ld.so.preload