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 R/W mode. This is intentional. This feature is meant for data that doesn't need further modifications after initialization. However the data might need to be released, for example as part of module unloading. The pool, therefore, can be destroyed. An example is provided, in the form of self-testing. Since it was advised to give an example of protecting real kernel data [1], a well known vulnerability has been used to demo an effective use of pmalloc. [1] http://www.openwall.com/lists/kernel-hardening/2018/03/29/7 However it turned out to be almost an how-to for attacking the kernel, so it was sent first to security@xxxxxxxxxx, for obtaining clearance about the publication. Changes since v21: [http://www.openwall.com/lists/kernel-hardening/2018/03/27/23] * fixed type mismatch error in use of max(), detected by gcc 7.3 * converted internal types into size_t * fixed leak of vmalloc memory in the self-test code Igor Stoppa (6): 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 Igor Stoppa (6): 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 Documentation/core-api/index.rst | 1 + Documentation/core-api/pmalloc.rst | 107 +++++++++++++++ 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 | 166 +++++++++++++++++++++++ include/linux/test_pmalloc.h | 24 ++++ include/linux/vmalloc.h | 5 +- init/main.c | 2 + mm/Kconfig | 16 +++ mm/Makefile | 2 + mm/pmalloc.c | 265 +++++++++++++++++++++++++++++++++++++ mm/test_pmalloc.c | 137 +++++++++++++++++++ mm/usercopy.c | 33 +++++ mm/vmalloc.c | 10 +- 16 files changed, 793 insertions(+), 5 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/test_pmalloc.c -- 2.14.1
