By feeding more random bits into mmap allocation, the effectiveness of KASLR will be improved, making attacks trying to bypass address randomisation more difficult.
Changed sysctl values are:
vm.mmap_rnd_bits = 32 (default: 28) vm.mmap_rnd_compat_bits = 16 (default: 8)
This patch backports the same change made in IPFire 2.x into IPFire 3.x .
Signed-off-by: Peter Müller peter.mueller@ipfire.org --- setup/setup.nm | 2 +- setup/sysctl/kernel-hardening.conf | 3 +++ 2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/setup/setup.nm b/setup/setup.nm index be0ca4ba0..09d94e23d 100644 --- a/setup/setup.nm +++ b/setup/setup.nm @@ -5,7 +5,7 @@
name = setup version = 3.0 -release = 13 +release = 14 arch = noarch
groups = Base Build System/Base diff --git a/setup/sysctl/kernel-hardening.conf b/setup/sysctl/kernel-hardening.conf index 9bb6e9f45..33e096c7c 100644 --- a/setup/sysctl/kernel-hardening.conf +++ b/setup/sysctl/kernel-hardening.conf @@ -4,3 +4,6 @@ kernel.kptr_restrict = 2 # Avoid kernel memory address exposures via dmesg. kernel.dmesg_restrict = 1
+# Improve KASLR effectiveness for mmap. +vm.mmap_rnd_bits = 32 +vm.mmap_rnd_compat_bits = 16
-
Peter Müller