[PATCH v6 01/14] mm, fs: Move randomize_stack_top from fs to mm
From: Alexandre Ghiti <alex@ghiti.fr>
Date: 2019-08-08 06:19:19
Also in:
linux-fsdevel, linux-mips, linux-mm, linux-riscv, lkml
Subsystem:
exec & binfmt api, elf, filesystems (vfs and infrastructure), memory management, memory management - core, the rest · Maintainers:
Kees Cook, Alexander Viro, Christian Brauner, Andrew Morton, David Hildenbrand, Linus Torvalds
This preparatory commit moves this function so that further introduction of generic topdown mmap layout is contained only in mm/util.c. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Acked-by: Kees Cook <redacted> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> --- fs/binfmt_elf.c | 20 -------------------- include/linux/mm.h | 2 ++ mm/util.c | 22 ++++++++++++++++++++++ 3 files changed, 24 insertions(+), 20 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index d4e11b2e04f6..cec3b4146440 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c@@ -670,26 +670,6 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, * libraries. There is no binary dependent code anywhere else. */ -#ifndef STACK_RND_MASK -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */ -#endif - -static unsigned long randomize_stack_top(unsigned long stack_top) -{ - unsigned long random_variable = 0; - - if (current->flags & PF_RANDOMIZE) { - random_variable = get_random_long(); - random_variable &= STACK_RND_MASK; - random_variable <<= PAGE_SHIFT; - } -#ifdef CONFIG_STACK_GROWSUP - return PAGE_ALIGN(stack_top) + random_variable; -#else - return PAGE_ALIGN(stack_top) - random_variable; -#endif -} - static int load_elf_binary(struct linux_binprm *bprm) { struct file *interpreter = NULL; /* to shut gcc up */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0334ca97c584..ae0e5d241eb8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -2351,6 +2351,8 @@ extern int install_special_mapping(struct mm_struct *mm, unsigned long addr, unsigned long len, unsigned long flags, struct page **pages); +unsigned long randomize_stack_top(unsigned long stack_top); + extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); extern unsigned long mmap_region(struct file *file, unsigned long addr,
diff --git a/mm/util.c b/mm/util.c
index e6351a80f248..15a4fb0f5473 100644
--- a/mm/util.c
+++ b/mm/util.c@@ -16,6 +16,8 @@ #include <linux/hugetlb.h> #include <linux/vmalloc.h> #include <linux/userfaultfd_k.h> +#include <linux/elf.h> +#include <linux/random.h> #include <linux/uaccess.h>
@@ -293,6 +295,26 @@ int vma_is_stack_for_current(struct vm_area_struct *vma) return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); } +#ifndef STACK_RND_MASK +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */ +#endif + +unsigned long randomize_stack_top(unsigned long stack_top) +{ + unsigned long random_variable = 0; + + if (current->flags & PF_RANDOMIZE) { + random_variable = get_random_long(); + random_variable &= STACK_RND_MASK; + random_variable <<= PAGE_SHIFT; + } +#ifdef CONFIG_STACK_GROWSUP + return PAGE_ALIGN(stack_top) + random_variable; +#else + return PAGE_ALIGN(stack_top) - random_variable; +#endif +} + #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) {
--
2.20.1
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