diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig | 19 | ||||
| -rw-r--r-- | mm/mmap.c | 3 | ||||
| -rw-r--r-- | mm/nommu.c | 3 | ||||
| -rw-r--r-- | mm/shmem.c | 2 |
4 files changed, 26 insertions, 1 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index c2b57d81e153..71830ba7b986 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -226,6 +226,25 @@ config HAVE_MLOCKED_PAGE_BIT config MMU_NOTIFIER bool +config DEFAULT_MMAP_MIN_ADDR + int "Low address space to protect from user allocation" + default 4096 + help + This is the portion of low virtual memory which should be protected + from userspace allocation. Keeping a user from writing to low pages + can help reduce the impact of kernel NULL pointer bugs. + + For most ia64, ppc64 and x86 users with lots of address space + a value of 65536 is reasonable and should cause no problems. + On arm and other archs it should not be higher than 32768. + Programs which use vm86 functionality would either need additional + permissions from either the LSM or the capabilities module or have + this protection disabled. + + This value can be changed after boot using the + /proc/sys/vm/mmap_min_addr tunable. + + config NOMMU_INITIAL_TRIM_EXCESS int "Turn on mmap() excess space trimming before booting" depends on !MMU diff --git a/mm/mmap.c b/mm/mmap.c index 6b7b1a95944b..2b43fa1aa3c8 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -87,6 +87,9 @@ int sysctl_overcommit_ratio = 50; /* default is 50% */ int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; struct percpu_counter vm_committed_as; +/* amount of vm to protect from userspace access */ +unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; + /* * Check that a process has enough memory to allocate a new virtual * mapping. 0 means there is enough memory for the allocation to diff --git a/mm/nommu.c b/mm/nommu.c index b571ef707428..2fd2ad5da98e 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -69,6 +69,9 @@ int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; int heap_stack_gap = 0; +/* amount of vm to protect from userspace access */ +unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; + atomic_long_t mmap_pages_allocated; EXPORT_SYMBOL(mem_map); diff --git a/mm/shmem.c b/mm/shmem.c index b25f95ce3db7..0132fbd45a23 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2659,6 +2659,7 @@ struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) if (error) goto close_file; #endif + ima_counts_get(file); return file; close_file: @@ -2684,7 +2685,6 @@ int shmem_zero_setup(struct vm_area_struct *vma) if (IS_ERR(file)) return PTR_ERR(file); - ima_shm_check(file); if (vma->vm_file) fput(vma->vm_file); vma->vm_file = file; |