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Wed, 07 Oct 2020 00:39:42 -0700 (PDT) Received: from localhost ([2a02:168:96c5:1:55ed:514f:6ad7:5bcc]) by smtp.gmail.com with ESMTPSA id r3sm1639024wrm.51.2020.10.07.00.39.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 00:39:41 -0700 (PDT) From: Jann Horn To: "David S. Miller" , sparclinux@vger.kernel.org, Andrew Morton , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Khalid Aziz , Christoph Hellwig , Anthony Yznaga , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org Subject: [PATCH 1/2] mm/mprotect: Call arch_validate_prot under mmap_lock and with length Date: Wed, 7 Oct 2020 09:39:31 +0200 Message-Id: <20201007073932.865218-1-jannh@google.com> X-Mailer: git-send-email 2.28.0.806.g8561365e88-goog MIME-Version: 1.0 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: arch_validate_prot() is a hook that can validate whether a given set of protection flags is valid in an mprotect() operation. It is given the set of protection flags and the address being modified. However, the address being modified can currently not actually be used in a meaningful way because: 1. Only the address is given, but not the length, and the operation can span multiple VMAs. Therefore, the callee can't actually tell which virtual address range, or which VMAs, are being targeted. 2. The mmap_lock is not held, meaning that if the callee were to check the VMA at @addr, that VMA would be unrelated to the one the operation is performed on. Currently, custom arch_validate_prot() handlers are defined by arm64, powerpc and sparc. arm64 and powerpc don't care about the address range, they just check the flags against CPU support masks. sparc's arch_validate_prot() attempts to look at the VMA, but doesn't take the mmap_lock. Change the function signature to also take a length, and move the arch_validate_prot() call in mm/mprotect.c down into the locked region. Cc: stable@vger.kernel.org Fixes: 9035cf9a97e4 ("mm: Add address parameter to arch_validate_prot()") Suggested-by: Khalid Aziz Suggested-by: Christoph Hellwig Signed-off-by: Jann Horn Reviewed-by: Khalid Aziz --- arch/arm64/include/asm/mman.h | 4 ++-- arch/powerpc/include/asm/mman.h | 3 ++- arch/powerpc/kernel/syscalls.c | 2 +- arch/sparc/include/asm/mman.h | 6 ++++-- include/linux/mman.h | 3 ++- mm/mprotect.c | 6 ++++-- 6 files changed, 15 insertions(+), 9 deletions(-) base-commit: c85fb28b6f999db9928b841f63f1beeb3074eeca diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h index 081ec8de9ea6..0876a87986dc 100644 --- a/arch/arm64/include/asm/mman.h +++ b/arch/arm64/include/asm/mman.h @@ -23,7 +23,7 @@ static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags) #define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags) static inline bool arch_validate_prot(unsigned long prot, - unsigned long addr __always_unused) + unsigned long addr __always_unused, unsigned long len __always_unused) { unsigned long supported = PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM; @@ -32,6 +32,6 @@ static inline bool arch_validate_prot(unsigned long prot, return (prot & ~supported) == 0; } -#define arch_validate_prot(prot, addr) arch_validate_prot(prot, addr) +#define arch_validate_prot(prot, addr, len) arch_validate_prot(prot, addr, len) #endif /* ! __ASM_MMAN_H__ */ diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h index 7cb6d18f5cd6..65dd9b594985 100644 --- a/arch/powerpc/include/asm/mman.h +++ b/arch/powerpc/include/asm/mman.h @@ -36,7 +36,8 @@ static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags) } #define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags) -static inline bool arch_validate_prot(unsigned long prot, unsigned long addr) +static inline bool arch_validate_prot(unsigned long prot, unsigned long addr, + unsigned long len) { if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_SAO)) return false; diff --git a/arch/powerpc/kernel/syscalls.c b/arch/powerpc/kernel/syscalls.c index 078608ec2e92..b1fabb97d138 100644 --- a/arch/powerpc/kernel/syscalls.c +++ b/arch/powerpc/kernel/syscalls.c @@ -43,7 +43,7 @@ static inline long do_mmap2(unsigned long addr, size_t len, { long ret = -EINVAL; - if (!arch_validate_prot(prot, addr)) + if (!arch_validate_prot(prot, addr, len)) goto out; if (shift) { diff --git a/arch/sparc/include/asm/mman.h b/arch/sparc/include/asm/mman.h index f94532f25db1..e85222c76585 100644 --- a/arch/sparc/include/asm/mman.h +++ b/arch/sparc/include/asm/mman.h @@ -52,9 +52,11 @@ static inline pgprot_t sparc_vm_get_page_prot(unsigned long vm_flags) return (vm_flags & VM_SPARC_ADI) ? __pgprot(_PAGE_MCD_4V) : __pgprot(0); } -#define arch_validate_prot(prot, addr) sparc_validate_prot(prot, addr) -static inline int sparc_validate_prot(unsigned long prot, unsigned long addr) +#define arch_validate_prot(prot, addr, len) sparc_validate_prot(prot, addr, len) +static inline int sparc_validate_prot(unsigned long prot, unsigned long addr, + unsigned long len) { + mmap_assert_write_locked(current->mm); if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_ADI)) return 0; if (prot & PROT_ADI) { diff --git a/include/linux/mman.h b/include/linux/mman.h index 6f34c33075f9..5b4d554d3189 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -96,7 +96,8 @@ static inline void vm_unacct_memory(long pages) * * Returns true if the prot flags are valid */ -static inline bool arch_validate_prot(unsigned long prot, unsigned long addr) +static inline bool arch_validate_prot(unsigned long prot, unsigned long addr, + unsigned long len) { return (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM)) == 0; } diff --git a/mm/mprotect.c b/mm/mprotect.c index ce8b8a5eacbb..e2d6b51acbf8 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -533,14 +533,16 @@ static int do_mprotect_pkey(unsigned long start, size_t len, end = start + len; if (end <= start) return -ENOMEM; - if (!arch_validate_prot(prot, start)) - return -EINVAL; reqprot = prot; if (mmap_write_lock_killable(current->mm)) return -EINTR; + error = -EINVAL; + if (!arch_validate_prot(prot, start, len)) + goto out; + /* * If userspace did not allocate the pkey, do not let * them use it here. From patchwork Wed Oct 7 07:39:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jann Horn X-Patchwork-Id: 11819877 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DD5B66CA for ; Wed, 7 Oct 2020 07:39:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8CF3F20B1F for ; Wed, 7 Oct 2020 07:39:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="Sws+UqMd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8CF3F20B1F Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7197B900004; 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Wed, 07 Oct 2020 00:39:43 -0700 (PDT) Received: from localhost ([2a02:168:96c5:1:55ed:514f:6ad7:5bcc]) by smtp.gmail.com with ESMTPSA id p9sm1475809wmm.4.2020.10.07.00.39.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 00:39:43 -0700 (PDT) From: Jann Horn To: "David S. Miller" , sparclinux@vger.kernel.org, Andrew Morton , linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Khalid Aziz , Christoph Hellwig , Anthony Yznaga , Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , linuxppc-dev@lists.ozlabs.org Subject: [PATCH 2/2] sparc: Check VMA range in sparc_validate_prot() Date: Wed, 7 Oct 2020 09:39:32 +0200 Message-Id: <20201007073932.865218-2-jannh@google.com> X-Mailer: git-send-email 2.28.0.806.g8561365e88-goog In-Reply-To: <20201007073932.865218-1-jannh@google.com> References: <20201007073932.865218-1-jannh@google.com> MIME-Version: 1.0 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: sparc_validate_prot() is called from do_mprotect_pkey() as arch_validate_prot(); it tries to ensure that an mprotect() call can't enable ADI on incompatible VMAs. The current implementation only checks that the VMA at the start address matches the rules for ADI mappings; instead, check all VMAs that will be affected by mprotect(). (This hook is called before mprotect() makes sure that the specified range is actually covered by VMAs, and mprotect() returns specific error codes when that's not the case. In order for mprotect() to still generate the same error codes for mprotect(, , ...|PROT_ADI), we need to *accept* cases where the range is not fully covered by VMAs.) Cc: stable@vger.kernel.org Fixes: 74a04967482f ("sparc64: Add support for ADI (Application Data Integrity)") Signed-off-by: Jann Horn Reviewed-by: Khalid Aziz --- compile-tested only, I don't have a Sparc ADI setup - might be nice if some Sparc person could test this? arch/sparc/include/asm/mman.h | 50 +++++++++++++++++++++-------------- 1 file changed, 30 insertions(+), 20 deletions(-) diff --git a/arch/sparc/include/asm/mman.h b/arch/sparc/include/asm/mman.h index e85222c76585..6dced75567c3 100644 --- a/arch/sparc/include/asm/mman.h +++ b/arch/sparc/include/asm/mman.h @@ -60,31 +60,41 @@ static inline int sparc_validate_prot(unsigned long prot, unsigned long addr, if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_ADI)) return 0; if (prot & PROT_ADI) { + struct vm_area_struct *vma, *next; + if (!adi_capable()) return 0; - if (addr) { - struct vm_area_struct *vma; + vma = find_vma(current->mm, addr); + /* if @addr is unmapped, let mprotect() deal with it */ + if (!vma || vma->vm_start > addr) + return 1; + while (1) { + /* ADI can not be enabled on PFN + * mapped pages + */ + if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) + return 0; - vma = find_vma(current->mm, addr); - if (vma) { - /* ADI can not be enabled on PFN - * mapped pages - */ - if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) - return 0; + /* Mergeable pages can become unmergeable + * if ADI is enabled on them even if they + * have identical data on them. This can be + * because ADI enabled pages with identical + * data may still not have identical ADI + * tags on them. Disallow ADI on mergeable + * pages. + */ + if (vma->vm_flags & VM_MERGEABLE) + return 0; - /* Mergeable pages can become unmergeable - * if ADI is enabled on them even if they - * have identical data on them. This can be - * because ADI enabled pages with identical - * data may still not have identical ADI - * tags on them. Disallow ADI on mergeable - * pages. - */ - if (vma->vm_flags & VM_MERGEABLE) - return 0; - } + /* reached the end of the range without errors? */ + if (addr+len <= vma->vm_end) + return 1; + next = vma->vm_next; + /* if a VMA hole follows, let mprotect() deal with it */ + if (!next || next->vm_start != vma->vm_end) + return 1; + vma = next; } } return 1;