From 23b0be480f341db26ce0dee7d3f6e67f8e0e166f Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Tue, 13 Jun 2017 17:18:03 -0400 Subject: cgroup: Make Kconfig prompt of debug cgroup more accurate The Kconfig prompt and description of the debug cgroup controller more accurate by saying that it is for debug purpose only and its interfaces are unstable. Signed-off-by: Waiman Long Signed-off-by: Tejun Heo --- init/Kconfig | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index 1d3475fc9496..5f9d13929ae0 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1205,11 +1205,14 @@ config CGROUP_BPF inet sockets. config CGROUP_DEBUG - bool "Example controller" + bool "Debug controller" default n + depends on DEBUG_KERNEL help This option enables a simple controller that exports - debugging information about the cgroups framework. + debugging information about the cgroups framework. This + controller is for control cgroup debugging only. Its + interfaces are not stable. Say N. -- cgit v1.2.3 From 7660a6fddcbae344de8583aa4092071312f110c3 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 6 Jul 2017 15:36:40 -0700 Subject: mm: allow slab_nomerge to be set at build time Some hardened environments want to build kernels with slab_nomerge already set (so that they do not depend on remembering to set the kernel command line option). This is desired to reduce the risk of kernel heap overflows being able to overwrite objects from merged caches and changes the requirements for cache layout control, increasing the difficulty of these attacks. By keeping caches unmerged, these kinds of exploits can usually only damage objects in the same cache (though the risk to metadata exploitation is unchanged). Link: http://lkml.kernel.org/r/20170620230911.GA25238@beast Signed-off-by: Kees Cook Cc: Daniel Micay Cc: David Windsor Cc: Eric Biggers Cc: Christoph Lameter Cc: Jonathan Corbet Cc: Daniel Micay Cc: David Windsor Cc: Eric Biggers Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: "Rafael J. Wysocki" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Mauro Carvalho Chehab Cc: "Paul E. McKenney" Cc: Arnd Bergmann Cc: Andy Lutomirski Cc: Nicolas Pitre Cc: Tejun Heo Cc: Daniel Mack Cc: Sebastian Andrzej Siewior Cc: Sergey Senozhatsky Cc: Helge Deller Cc: Rik van Riel Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- init/Kconfig | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index b0fcbb2c6f56..8514b25db21c 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1548,6 +1548,20 @@ config SLOB endchoice +config SLAB_MERGE_DEFAULT + bool "Allow slab caches to be merged" + default y + help + For reduced kernel memory fragmentation, slab caches can be + merged when they share the same size and other characteristics. + This carries a risk of kernel heap overflows being able to + overwrite objects from merged caches (and more easily control + cache layout), which makes such heap attacks easier to exploit + by attackers. By keeping caches unmerged, these kinds of exploits + can usually only damage objects in the same cache. To disable + merging at runtime, "slab_nomerge" can be passed on the kernel + command line. + config SLAB_FREELIST_RANDOM default n depends on SLAB || SLUB -- cgit v1.2.3 From ee7998c50c2697737c6530431709f77c852bf0d6 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 12 Jul 2017 14:34:04 -0700 Subject: random: do not ignore early device randomness The add_device_randomness() function would ignore incoming bytes if the crng wasn't ready. This additionally makes sure to make an early enough call to add_latent_entropy() to influence the initial stack canary, which is especially important on non-x86 systems where it stays the same through the life of the boot. Link: http://lkml.kernel.org/r/20170626233038.GA48751@beast Signed-off-by: Kees Cook Cc: "Theodore Ts'o" Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Ingo Molnar Cc: Jessica Yu Cc: Steven Rostedt (VMware) Cc: Viresh Kumar Cc: Tejun Heo Cc: Prarit Bhargava Cc: Lokesh Vutla Cc: Nicholas Piggin Cc: AKASHI Takahiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- init/main.c | 1 + 1 file changed, 1 insertion(+) (limited to 'init') diff --git a/init/main.c b/init/main.c index df58a416dd1d..052481fbe363 100644 --- a/init/main.c +++ b/init/main.c @@ -518,6 +518,7 @@ asmlinkage __visible void __init start_kernel(void) /* * Set up the initial canary ASAP: */ + add_latent_entropy(); boot_init_stack_canary(); cgroup_init_early(); -- cgit v1.2.3