This patch-set introduces the possibility of protecting memory that has been allocated dynamically. The memory is managed in pools: when a memory pool is protected, all the memory that is currently part of it, will become R/O. A R/O pool can be expanded (adding more protectable memory). It can also be destroyed, to recover its memory, but it cannot be turned back into normal R/W mode. This is intentional. This feature is meant for data that either doesn't need further modifications after initialization, or it will change very seldom. The data might need to be released, for example as part of module unloading. The pool, therefore, can be destroyed. For those cases where the data is never completely stable, however it can stay unmodified for very long periods, there is a possibility of allocating it from a "rare write" pool, which allows modification to its data, through an helper function. I did not want to overcomplicate the first version of rare write, but it might be needed to add disabling/enabling of preemption, however I would appreciate comments in general about the implementation through transient remapping. An example is provided, showing how to protect one of hte internal states of SELinux. Changes since v22: [http://www.openwall.com/lists/kernel-hardening/2018/04/13/3] - refactored some helper functions in a separate local header - expanded the documentation - introduction of rare write support - example with SELinux "initialized" field Igor Stoppa (9): struct page: add field for vm_struct vmalloc: rename llist field in vmap_area Protectable Memory Documentation for Pmalloc Pmalloc selftest lkdtm: crash on overwriting protected pmalloc var Pmalloc Rare Write: modify selected pools Preliminary self test for pmalloc rare write Protect SELinux initialized state with pmalloc Documentation/core-api/index.rst | 1 + Documentation/core-api/pmalloc.rst | 189 ++++++++++++++++++++++++++ drivers/misc/lkdtm/core.c | 3 + drivers/misc/lkdtm/lkdtm.h | 1 + drivers/misc/lkdtm/perms.c | 25 ++++ include/linux/mm_types.h | 1 + include/linux/pmalloc.h | 170 ++++++++++++++++++++++++ include/linux/test_pmalloc.h | 24 ++++ include/linux/vmalloc.h | 6 +- init/main.c | 2 + mm/Kconfig | 16 +++ mm/Makefile | 2 + mm/pmalloc.c | 258 ++++++++++++++++++++++++++++++++++++ mm/pmalloc_helpers.h | 210 +++++++++++++++++++++++++++++ mm/test_pmalloc.c | 213 +++++++++++++++++++++++++++++ mm/usercopy.c | 9 ++ mm/vmalloc.c | 10 +- security/selinux/hooks.c | 12 +- security/selinux/include/security.h | 2 +- security/selinux/ss/services.c | 51 ++++--- 20 files changed, 1174 insertions(+), 31 deletions(-) create mode 100644 Documentation/core-api/pmalloc.rst create mode 100644 include/linux/pmalloc.h create mode 100644 include/linux/test_pmalloc.h create mode 100644 mm/pmalloc.c create mode 100644 mm/pmalloc_helpers.h create mode 100644 mm/test_pmalloc.c -- 2.14.1
