Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753663AbbKMI2L (ORCPT ); Fri, 13 Nov 2015 03:28:11 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:54316 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750760AbbKMI2J (ORCPT ); Fri, 13 Nov 2015 03:28:09 -0500 Message-ID: <56459EED.4030109@huawei.com> Date: Fri, 13 Nov 2015 16:27:25 +0800 From: Xishi Qiu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Laura Abbott CC: Catalin Marinas , Will Deacon , Ard Biesheuvel , "Zhong Jiang" , , , Kees Cook , "Mark Rutland" Subject: Re: [PATCHv2 2/2] arm64: Allow changing of attributes outside of modules References: <1447207057-11323-1-git-send-email-labbott@fedoraproject.org> <1447207057-11323-3-git-send-email-labbott@fedoraproject.org> In-Reply-To: <1447207057-11323-3-git-send-email-labbott@fedoraproject.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.25.179] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A0B0202.56459F09.020B,ss=1,re=0.000,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2011-05-27 18:58:46 X-Mirapoint-Loop-Id: 28a438a553cdd4a5b281b113530c59a5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8738 Lines: 307 On 2015/11/11 9:57, Laura Abbott wrote: > Currently, the set_memory_* functions that are implemented for arm64 > are restricted to module addresses only. This was mostly done > because arm64 maps normal zone memory with larger page sizes to > improve TLB performance. This has the side effect though of making it > difficult to adjust attributes at the PAGE_SIZE granularity. There are > an increasing number of use cases related to security where it is > necessary to change the attributes of kernel memory. Add functionality > to the page attribute changing code under a Kconfig to let systems > designers decide if they want to make the trade off of security for TLB > pressure. > > Signed-off-by: Laura Abbott > --- > v2: Re-worked to account for the full range of addresses. Will also just > update the section blocks instead of splitting if the addresses are aligned > properly. > --- > arch/arm64/Kconfig | 12 ++++ > arch/arm64/mm/mm.h | 3 + > arch/arm64/mm/mmu.c | 2 +- > arch/arm64/mm/pageattr.c | 174 +++++++++++++++++++++++++++++++++++++++++------ > 4 files changed, 170 insertions(+), 21 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 851fe11..46725e8 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -521,6 +521,18 @@ config ARCH_HAS_CACHE_LINE_SIZE > > source "mm/Kconfig" > > +config DEBUG_CHANGE_PAGEATTR > + bool "Allow all kernel memory to have attributes changed" > + default y > + help > + If this option is selected, APIs that change page attributes > + (RW <-> RO, X <-> NX) will be valid for all memory mapped in > + the kernel space. The trade off is that there may be increased > + TLB pressure from finer grained page mapping. Turn on this option > + if security is more important than performance > + > + If in doubt, say Y > + > config SECCOMP > bool "Enable seccomp to safely compute untrusted bytecode" > ---help--- > diff --git a/arch/arm64/mm/mm.h b/arch/arm64/mm/mm.h > index ef47d99..7b0dcc4 100644 > --- a/arch/arm64/mm/mm.h > +++ b/arch/arm64/mm/mm.h > @@ -1,3 +1,6 @@ > extern void __init bootmem_init(void); > > void fixup_init(void); > + > +void split_pud(pud_t *old_pud, pmd_t *pmd); > +void split_pmd(pmd_t *pmd, pte_t *pte); > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 496c3fd..9353e3c 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -73,7 +73,7 @@ static void __init *early_alloc(unsigned long sz) > /* > * remap a PMD into pages > */ > -static void split_pmd(pmd_t *pmd, pte_t *pte) > +void split_pmd(pmd_t *pmd, pte_t *pte) > { > unsigned long pfn = pmd_pfn(*pmd); > unsigned long addr = pfn << PAGE_SHIFT; > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index 3571c73..4a95fed 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -15,25 +15,162 @@ > #include > #include > > +#include > #include > #include > > -struct page_change_data { > - pgprot_t set_mask; > - pgprot_t clear_mask; > -}; > +#include "mm.h" > > -static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr, > - void *data) > +static int update_pte_range(struct mm_struct *mm, pmd_t *pmd, > + unsigned long addr, unsigned long end, > + pgprot_t clear, pgprot_t set) > { > - struct page_change_data *cdata = data; > - pte_t pte = *ptep; > + pte_t *pte; > + int err = 0; > + > + if (pmd_sect(*pmd)) { > + if (!IS_ENABLED(CONFIG_DEBUG_CHANGE_PAGEATTR)) { > + err = -EINVAL; > + goto out; > + } > + pte = pte_alloc_one_kernel(&init_mm, addr); > + if (!pte) { > + err = -ENOMEM; > + goto out; > + } > + split_pmd(pmd, pte); > + __pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE); > + } > + > + > + pte = pte_offset_kernel(pmd, addr); > + if (pte_none(*pte)) { > + err = -EFAULT; > + goto out; > + } > + > + do { > + pte_t p = *pte; > + > + p = clear_pte_bit(p, clear); > + p = set_pte_bit(p, set); > + set_pte(pte, p); > + > + } while (pte++, addr += PAGE_SIZE, addr != end); > + > +out: > + return err; > +} > + > + > +static int update_pmd_range(struct mm_struct *mm, pud_t *pud, > + unsigned long addr, unsigned long end, > + pgprot_t clear, pgprot_t set) > +{ > + pmd_t *pmd; > + unsigned long next; > + int err = 0; > + > + if (pud_sect(*pud)) { > + if (!IS_ENABLED(CONFIG_DEBUG_CHANGE_PAGEATTR)) { > + err = -EINVAL; > + goto out; > + } > + pmd = pmd_alloc_one(&init_mm, addr); > + if (!pmd) { > + err = -ENOMEM; > + goto out; > + } > + split_pud(pud, pmd); > + pud_populate(&init_mm, pud, pmd); > + } > + > > - pte = clear_pte_bit(pte, cdata->clear_mask); > - pte = set_pte_bit(pte, cdata->set_mask); > + pmd = pmd_offset(pud, addr); > + if (pmd_none(*pmd)) { > + err = -EFAULT; > + goto out; > + } > + > + do { > + next = pmd_addr_end(addr, end); > + if (((addr | end) & ~SECTION_MASK) == 0) { Hi Laura, Why not like this? if (pmd_sect(*pmd) && ((addr | nest) & ~SECTION_MASK) == 0) { > + unsigned long paddr = pmd_pfn(*pmd) << PAGE_SHIFT; > + pgprot_t prot = __pgprot((pmd_val(*pmd) ^ paddr)); > + > + pgprot_val(prot) &= ~pgprot_val(clear); > + pgprot_val(prot) |= pgprot_val(set); > + set_pmd(pmd, __pmd(paddr | pgprot_val(prot))); > + } else { > + err = update_pte_range(mm, pmd, addr, next, clear, set); > + } > + if (err) > + break; > + } while (pmd++, addr = next, addr != end); > +out: > + return err; > +} > + > + > +static int update_pud_range(struct mm_struct *mm, pgd_t *pgd, > + unsigned long addr, unsigned long end, > + pgprot_t clear, pgprot_t set) > +{ > + pud_t *pud; > + unsigned long next; > + int err = 0; > + > + pud = pud_offset(pgd, addr); > + if (pud_none(*pud)) { > + err = -EFAULT; > + goto out; > + } > > - set_pte(ptep, pte); > - return 0; > + do { > + next = pud_addr_end(addr, end); > + if (pud_sect(*pud) && ((addr | next) & ~PUD_MASK) == 0) { > + unsigned long paddr = pud_pfn(*pud) << PAGE_SHIFT; > + pgprot_t prot = __pgprot(pud_val(*pud) ^ paddr); > + > + pgprot_val(prot) &= ~pgprot_val(clear); > + pgprot_val(prot) |= pgprot_val(set); > + set_pud(pud, __pud(paddr | pgprot_val(prot))); > + } else { > + err = update_pmd_range(mm, pud, addr, next, clear, set); > + } > + if (err) > + break; > + } while (pud++, addr = next, addr != end); > + > +out: > + return err; > +} > + > +static int update_page_range(unsigned long addr, > + unsigned long end, pgprot_t clear, > + pgprot_t set) > +{ > + pgd_t *pgd; > + unsigned long next; > + int err; > + struct mm_struct *mm = &init_mm; > + > + BUG_ON(addr >= end); > + pgd = pgd_offset(mm, addr); > + if (pgd_none(*pgd)) { > + err = -EFAULT; > + goto out; > + } > + > + do { > + next = pgd_addr_end(addr, end); > + err = update_pud_range(mm, pgd, addr, next, clear, set); > + if (err) > + break; > + } while (pgd++, addr = next, addr != end); > + > +out: > + return err; > } > > static int change_memory_common(unsigned long addr, int numpages, > @@ -43,7 +180,6 @@ static int change_memory_common(unsigned long addr, int numpages, > unsigned long size = PAGE_SIZE*numpages; > unsigned long end = start + size; > int ret; > - struct page_change_data data; > > if (!PAGE_ALIGNED(addr)) { > start &= PAGE_MASK; > @@ -51,17 +187,15 @@ static int change_memory_common(unsigned long addr, int numpages, > WARN_ON_ONCE(1); > } > > - if (start < MODULES_VADDR || start >= MODULES_END) > + if (start < PAGE_OFFSET && !is_vmalloc_addr((void *)start) && > + (start < MODULES_VADDR || start >= MODULES_END)) How about abstracting "start < MODULES_VADDR || start >= MODULES_END" to a new function? e.g. is_module_addr(), however it is a little confusion with is_module_address(). > return -EINVAL; > > - if (end < MODULES_VADDR || end >= MODULES_END) > + if (end < PAGE_OFFSET && !is_vmalloc_addr((void *)end) && > + (end < MODULES_VADDR || end >= MODULES_END)) > return -EINVAL; > It will not filter this case, start in module range and end in vmalloc range, right? start and end should be both in one range. Thanks, Xishi Qiu > - data.set_mask = set_mask; > - data.clear_mask = clear_mask; > - > - ret = apply_to_page_range(&init_mm, start, size, change_page_range, > - &data); > + ret = update_page_range(addr, end, clear_mask, set_mask); > > flush_tlb_kernel_range(start, end); > return ret; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/