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[217.70.183.195]) by mx.google.com with ESMTPS id k24si31378163ejz.188.2019.08.07.23.32.19 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 07 Aug 2019 23:32:19 -0700 (PDT) Received-SPF: neutral (google.com: 217.70.183.195 is neither permitted nor denied by best guess record for domain of alex@ghiti.fr) client-ip=217.70.183.195; Authentication-Results: mx.google.com; spf=neutral (google.com: 217.70.183.195 is neither permitted nor denied by best guess record for domain of alex@ghiti.fr) smtp.mailfrom=alex@ghiti.fr X-Originating-IP: 79.86.19.127 Received: from alex.numericable.fr (127.19.86.79.rev.sfr.net [79.86.19.127]) (Authenticated sender: alex@ghiti.fr) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id B4C8060004; Thu, 8 Aug 2019 06:32:14 +0000 (UTC) From: Alexandre Ghiti To: Andrew Morton Cc: Paul Walmsley , Luis Chamberlain , Christoph Hellwig , Russell King , Catalin Marinas , Will Deacon , Ralf Baechle , Paul Burton , James Hogan , Palmer Dabbelt , Albert Ou , Alexander Viro , Kees Cook , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Alexandre Ghiti Subject: [PATCH v6 13/14] mips: Use generic mmap top-down layout and brk randomization Date: Thu, 8 Aug 2019 02:17:55 -0400 Message-Id: <20190808061756.19712-14-alex@ghiti.fr> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190808061756.19712-1-alex@ghiti.fr> References: <20190808061756.19712-1-alex@ghiti.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: mips uses a top-down layout by default that exactly fits the generic functions, so get rid of arch specific code and use the generic version by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE, use the generic version of arch_randomize_brk since it also fits. Note that this commit also removes the possibility for mips to have elf randomization and no MMU: without MMU, the security added by randomization is worth nothing. Signed-off-by: Alexandre Ghiti Acked-by: Paul Burton Reviewed-by: Kees Cook Reviewed-by: Luis Chamberlain --- arch/mips/Kconfig | 2 +- arch/mips/include/asm/processor.h | 5 -- arch/mips/mm/mmap.c | 96 ------------------------------- 3 files changed, 1 insertion(+), 102 deletions(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index d50fafd7bf3a..4e85d7d2cf1a 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -5,7 +5,6 @@ config MIPS select ARCH_32BIT_OFF_T if !64BIT select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT select ARCH_CLOCKSOURCE_DATA - select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_SUPPORTS_UPROBES @@ -13,6 +12,7 @@ config MIPS select ARCH_USE_CMPXCHG_LOCKREF if 64BIT select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU select ARCH_WANT_IPC_PARSE_VERSION select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index aca909bd7841..fba18d4a9190 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -29,11 +29,6 @@ extern unsigned int vced_count, vcei_count; -/* - * MIPS does have an arch_pick_mmap_layout() - */ -#define HAVE_ARCH_PICK_MMAP_LAYOUT 1 - #ifdef CONFIG_32BIT #ifdef CONFIG_KVM_GUEST /* User space process size is limited to 1GB in KVM Guest Mode */ diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index d5106c26ac6a..00fe90c6db3e 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -16,49 +16,10 @@ #include #include #include -#include -#include unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ EXPORT_SYMBOL(shm_align_mask); -/* gap between mmap and stack */ -#define MIN_GAP (128*1024*1024UL) -#define MAX_GAP ((STACK_TOP)/6*5) -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) - -static int mmap_is_legacy(struct rlimit *rlim_stack) -{ - if (current->personality & ADDR_COMPAT_LAYOUT) - return 1; - - if (rlim_stack->rlim_cur == RLIM_INFINITY) - return 1; - - return sysctl_legacy_va_layout; -} - -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) -{ - unsigned long gap = rlim_stack->rlim_cur; - unsigned long pad = stack_guard_gap; - - /* Account for stack randomization if necessary */ - if (current->flags & PF_RANDOMIZE) - pad += (STACK_RND_MASK << PAGE_SHIFT); - - /* Values close to RLIM_INFINITY can overflow. */ - if (gap + pad > gap) - gap += pad; - - if (gap < MIN_GAP) - gap = MIN_GAP; - else if (gap > MAX_GAP) - gap = MAX_GAP; - - return PAGE_ALIGN(STACK_TOP - gap - rnd); -} - #define COLOUR_ALIGN(addr, pgoff) \ ((((addr) + shm_align_mask) & ~shm_align_mask) + \ (((pgoff) << PAGE_SHIFT) & shm_align_mask)) @@ -156,63 +117,6 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, addr0, len, pgoff, flags, DOWN); } -unsigned long arch_mmap_rnd(void) -{ - unsigned long rnd; - -#ifdef CONFIG_COMPAT - if (TASK_IS_32BIT_ADDR) - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); - else -#endif /* CONFIG_COMPAT */ - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); - - return rnd << PAGE_SHIFT; -} - -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) -{ - unsigned long random_factor = 0UL; - - if (current->flags & PF_RANDOMIZE) - random_factor = arch_mmap_rnd(); - - if (mmap_is_legacy(rlim_stack)) { - mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; - mm->get_unmapped_area = arch_get_unmapped_area; - } else { - mm->mmap_base = mmap_base(random_factor, rlim_stack); - mm->get_unmapped_area = arch_get_unmapped_area_topdown; - } -} - -static inline unsigned long brk_rnd(void) -{ - unsigned long rnd = get_random_long(); - - rnd = rnd << PAGE_SHIFT; - /* 32MB for 32bit, 1GB for 64bit */ - if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task()) - rnd = rnd & (SZ_32M - 1); - else - rnd = rnd & (SZ_1G - 1); - - return rnd; -} - -unsigned long arch_randomize_brk(struct mm_struct *mm) -{ - unsigned long base = mm->brk; - unsigned long ret; - - ret = PAGE_ALIGN(base + brk_rnd()); - - if (ret < mm->brk) - return mm->brk; - - return ret; -} - bool __virt_addr_valid(const volatile void *kaddr) { unsigned long vaddr = (unsigned long)kaddr; -- 2.20.1