From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id 005356B0030 for ; Thu, 22 Mar 2018 12:36:55 -0400 (EDT) Received: by mail-lf0-f69.google.com with SMTP id g13-v6so3002979lfl.15 for ; Thu, 22 Mar 2018 09:36:54 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id f95-v6sor1846449lfi.105.2018.03.22.09.36.53 for (Google Transport Security); Thu, 22 Mar 2018 09:36:53 -0700 (PDT) From: Ilya Smith Subject: [RFC PATCH v2 1/2] Randomization of address chosen by mmap. Date: Thu, 22 Mar 2018 19:36:37 +0300 Message-Id: <1521736598-12812-2-git-send-email-blackzert@gmail.com> In-Reply-To: <1521736598-12812-1-git-send-email-blackzert@gmail.com> References: <1521736598-12812-1-git-send-email-blackzert@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@synopsys.com, linux@armlinux.org.uk, tony.luck@intel.com, fenghua.yu@intel.com, jhogan@kernel.org, ralf@linux-mips.org, jejb@parisc-linux.org, deller@gmx.de, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, nyc@holomorphy.com, viro@zeniv.linux.org.uk, arnd@arndb.de, blackzert@gmail.com, gregkh@linuxfoundation.org, deepa.kernel@gmail.com, mhocko@suse.com, hughd@google.com, kstewart@linuxfoundation.org, pombredanne@nexb.com, akpm@linux-foundation.org, steve.capper@arm.com, punit.agrawal@arm.com, paul.burton@mips.com, aneesh.kumar@linux.vnet.ibm.com, npiggin@gmail.com, keescook@chromium.org, bhsharma@redhat.com, riel@redhat.com, nitin.m.gupta@oracle.com, kirill.shutemov@linux.intel.com, dan.j.williams@intel.com, jack@suse.cz, ross.zwisler@linux.intel.com, jglisse@redhat.com, willy@infradead.org, aarcange@redhat.com, oleg@redhat.com, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org Signed-off-by: Ilya Smith --- include/linux/mm.h | 16 ++++-- mm/mmap.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 175 insertions(+), 5 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index ad06d42..c716257 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -25,6 +25,7 @@ #include #include #include +#include struct mempolicy; struct anon_vma; @@ -2253,6 +2254,13 @@ struct vm_unmapped_area_info { unsigned long align_offset; }; +#ifndef CONFIG_MMU +#define randomize_va_space 0 +#else +extern int randomize_va_space; +#endif + +extern unsigned long unmapped_area_random(struct vm_unmapped_area_info *info); extern unsigned long unmapped_area(struct vm_unmapped_area_info *info); extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info); @@ -2268,6 +2276,9 @@ extern unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info); static inline unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) { + /* How about 32 bit process?? */ + if ((current->flags & PF_RANDOMIZE) && randomize_va_space > 3) + return unmapped_area_random(info); if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) return unmapped_area_topdown(info); else @@ -2529,11 +2540,6 @@ int drop_caches_sysctl_handler(struct ctl_table *, int, void drop_slab(void); void drop_slab_node(int nid); -#ifndef CONFIG_MMU -#define randomize_va_space 0 -#else -extern int randomize_va_space; -#endif const char * arch_vma_name(struct vm_area_struct *vma); void print_vma_addr(char *prefix, unsigned long rip); diff --git a/mm/mmap.c b/mm/mmap.c index 9efdc021..ba9cebb 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -45,6 +45,7 @@ #include #include #include +#include #include #include @@ -1780,6 +1781,169 @@ unsigned long mmap_region(struct file *file, unsigned long addr, return error; } +unsigned long unmapped_area_random(struct vm_unmapped_area_info *info) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma = NULL; + struct vm_area_struct *visited_vma = NULL; + unsigned long entropy[2]; + unsigned long length, low_limit, high_limit, gap_start, gap_end; + unsigned long addr = 0; + + /* get entropy with prng */ + prandom_bytes(&entropy, sizeof(entropy)); + /* small hack to prevent EPERM result */ + info->low_limit = max(info->low_limit, mmap_min_addr); + + /* Adjust search length to account for worst case alignment overhead */ + length = info->length + info->align_mask; + if (length < info->length) + return -ENOMEM; + + /* + * Adjust search limits by the desired length. + * See implementation comment at top of unmapped_area(). + */ + gap_end = info->high_limit; + if (gap_end < length) + return -ENOMEM; + high_limit = gap_end - length; + + low_limit = info->low_limit + info->align_mask; + if (low_limit >= high_limit) + return -ENOMEM; + + /* Choose random addr in limit range */ + addr = entropy[0] % ((high_limit - low_limit) >> PAGE_SHIFT); + addr = low_limit + (addr << PAGE_SHIFT); + addr += (info->align_offset - addr) & info->align_mask; + + /* Check if rbtree root looks promising */ + if (RB_EMPTY_ROOT(&mm->mm_rb)) + return -ENOMEM; + + vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); + if (vma->rb_subtree_gap < length) + return -ENOMEM; + /* use randomly chosen address to find closest suitable gap */ + while (true) { + gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; + gap_end = vm_start_gap(vma); + if (gap_end < low_limit) + break; + if (addr < vm_start_gap(vma)) { + /* random said check left */ + if (vma->vm_rb.rb_left) { + struct vm_area_struct *left = + rb_entry(vma->vm_rb.rb_left, + struct vm_area_struct, vm_rb); + if (addr <= vm_start_gap(left) && + left->rb_subtree_gap >= length) { + vma = left; + continue; + } + } + } else if (addr >= vm_end_gap(vma)) { + /* random said check right */ + if (vma->vm_rb.rb_right) { + struct vm_area_struct *right = + rb_entry(vma->vm_rb.rb_right, + struct vm_area_struct, vm_rb); + /* it want go to the right */ + if (right->rb_subtree_gap >= length) { + vma = right; + continue; + } + } + } + if (gap_start < low_limit) { + if (gap_end <= low_limit) + break; + gap_start = low_limit; + } else if (gap_end > info->high_limit) { + if (gap_start >= info->high_limit) + break; + gap_end = info->high_limit; + } + if (gap_end > gap_start && + gap_end - gap_start >= length) + goto found; + visited_vma = vma; + break; + } + /* not found */ + while (true) { + gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; + + if (gap_start <= high_limit && vma->vm_rb.rb_right) { + struct vm_area_struct *right = + rb_entry(vma->vm_rb.rb_right, + struct vm_area_struct, vm_rb); + if (right->rb_subtree_gap >= length && + right != visited_vma) { + vma = right; + continue; + } + } + +check_current: + /* Check if current node has a suitable gap */ + gap_end = vm_start_gap(vma); + if (gap_end <= low_limit) + goto go_back; + + if (gap_start < low_limit) + gap_start = low_limit; + + if (gap_start <= high_limit && + gap_end > gap_start && gap_end - gap_start >= length) + goto found; + + /* Visit left subtree if it looks promising */ + if (vma->vm_rb.rb_left) { + struct vm_area_struct *left = + rb_entry(vma->vm_rb.rb_left, + struct vm_area_struct, vm_rb); + if (left->rb_subtree_gap >= length && + vm_end_gap(left) > low_limit && + left != visited_vma) { + vma = left; + continue; + } + } +go_back: + /* Go back up the rbtree to find next candidate node */ + while (true) { + struct rb_node *prev = &vma->vm_rb; + + if (!rb_parent(prev)) + return -ENOMEM; + visited_vma = vma; + vma = rb_entry(rb_parent(prev), + struct vm_area_struct, vm_rb); + if (prev == vma->vm_rb.rb_right) { + gap_start = vma->vm_prev ? + vm_end_gap(vma->vm_prev) : low_limit; + goto check_current; + } + } + } +found: + /* We found a suitable gap. Clip it with the original high_limit. */ + if (gap_end > info->high_limit) + gap_end = info->high_limit; + gap_end -= info->length; + gap_end -= (gap_end - info->align_offset) & info->align_mask; + /* only one suitable page */ + if (gap_end == gap_start) + return gap_start; + addr = entropy[1] % (min((gap_end - gap_start) >> PAGE_SHIFT, + 0x10000UL)); + addr = gap_end - (addr << PAGE_SHIFT); + addr += (info->align_offset - addr) & info->align_mask; + return addr; +} + unsigned long unmapped_area(struct vm_unmapped_area_info *info) { /* -- 2.7.4