Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932411AbbKMCnb (ORCPT ); Thu, 12 Nov 2015 21:43:31 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:62578 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754220AbbKMCna (ORCPT ); Thu, 12 Nov 2015 21:43:30 -0500 Message-ID: <56454CD8.8080608@huawei.com> Date: Fri, 13 Nov 2015 10:37:12 +0800 From: zhong jiang User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Laura Abbott CC: Catalin Marinas , Will Deacon , Ard Biesheuvel , , , Kees Cook , Xishi Qiu , "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> <56447E42.7050002@huawei.com> In-Reply-To: <56447E42.7050002@huawei.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.29.68] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090205.56454CE7.0007,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: cb40b39eb4f36bd7bc3c10d78a1f8882 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9290 Lines: 313 On 2015/11/12 19:55, zhong jiang wrote: > 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; >> + } >> + > > we try to preserve the section area, but the addr | end does not ensure that > physical memory is alignment. In addtion, if numpages cross section area, and > addr points to the physical memory is alignment to the section. In this case, > we should consider to retain the section. > >> + do { >> + next = pmd_addr_end(addr, end); >> + if (((addr | end) & ~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)) >> 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; >> >> - 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/ > > . > Hi Laura In change_memory_common, why the address is so restricted ? Thanks zhongjiang -- 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/