[PATCH v3 1/4] mm: mmap: Add new /proc tunable for mmap_base ASLR.
From: Daniel Cashman <hidden>
Date: 2015-11-19 00:14:20
Also in:
linux-mm, lkml
On 11/18/2015 03:20 PM, Daniel Cashman wrote:
============================================================== +mmap_rnd_bits: + +This value can be used to select the number of bits to use to +determine the random offset to the base address of vma regions +resulting from mmap allocations on architectures which support +tuning address space randomization. This value will be bounded +by the architecture's minimum and maximum supported values. + +This value can be changed after boot using the +/proc/sys/kernel/mmap_rnd_bits tunable + +============================================================== + +mmap_rnd_compat_bits: + +This value can be used to select the number of bits to use to +determine the random offset to the base address of vma regions +resulting from mmap allocations for applications run in +compatibility mode on architectures which support tuning address +space randomization. This value will be bounded by the +architecture's minimum and maximum supported values. + +This value can be changed after boot using the +/proc/sys/kernel/mmap_rnd_compat_bits tunable + +==============================================================
As Kees pointed out in my erroneously sent (missing v3 prefix) patch-set: the /proc/sys/kernel/ entries were not changed to reflect the move to /proc/sys/vm/.
quoted hunk ↗ jump to hunk
diff --git a/include/linux/mm.h b/include/linux/mm.h index 00bad77..7d39828 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h@@ -51,6 +51,17 @@ extern int sysctl_legacy_va_layout; #define sysctl_legacy_va_layout 0 #endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS +extern int mmap_rnd_bits_min; +extern int mmap_rnd_bits_max; +extern int mmap_rnd_bits; +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS +extern int mmap_rnd_compat_bits_min; +extern int mmap_rnd_compat_bits_max; +extern int mmap_rnd_compat_bits; +#endif + #include <asm/page.h> #include <asm/pgtable.h> #include <asm/processor.h>diff --git a/kernel/sysctl.c b/kernel/sysctl.c index dc6858d..40e5de6 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c@@ -1568,6 +1568,28 @@ static struct ctl_table vm_table[] = { .mode = 0644, .proc_handler = proc_doulongvec_minmax, }, +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS + { + .procname = "mmap_rnd_bits", + .data = &mmap_rnd_bits, + .maxlen = sizeof(mmap_rnd_bits), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &mmap_rnd_bits_min, + .extra2 = &mmap_rnd_bits_max, + }, +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS + { + .procname = "mmap_rnd_compat_bits", + .data = &mmap_rnd_compat_bits, + .maxlen = sizeof(mmap_rnd_compat_bits), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &mmap_rnd_compat_bits_min, + .extra2 = &mmap_rnd_compat_bits_max, + }, +#endif { } };diff --git a/mm/mmap.c b/mm/mmap.c index 2ce04a6..aa49841 100644 --- a/mm/mmap.c +++ b/mm/mmap.c@@ -58,6 +58,18 @@ #define arch_rebalance_pgtables(addr, len) (addr) #endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS +int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; +int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; +int mmap_rnd_bits = CONFIG_ARCH_MMAP_RND_BITS; +#endif +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS +int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; +int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; +int mmap_rnd_compat_bits = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; +#endif +
Again from Kees in my erroneously sent (missing v3 prefix) patch-set: the min/max should be const.