From: Khalid Aziz <khalid.aziz@oracle.com>
To: Jann Horn <jannh@google.com>,
"David S. Miller" <davem@davemloft.net>,
sparclinux@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
Anthony Yznaga <anthony.yznaga@oracle.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/2] sparc: Check VMA range in sparc_validate_prot()
Date: Wed, 7 Oct 2020 14:15:28 -0600 [thread overview]
Message-ID: <230d612d-75e8-34e0-00d6-b0f7274e692c@oracle.com> (raw)
In-Reply-To: <20201007073932.865218-2-jannh@google.com>
On 10/7/20 1:39 AM, Jann Horn wrote:
> 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(<unmapped_ptr>, <len>, ...|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 <jannh@google.com>
> ---
> 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(-)
Looks good to me.
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
>
> 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;
>
next prev parent reply other threads:[~2020-10-07 20:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-07 7:39 [PATCH 1/2] mm/mprotect: Call arch_validate_prot under mmap_lock and with length Jann Horn
2020-10-07 7:39 ` [PATCH 2/2] sparc: Check VMA range in sparc_validate_prot() Jann Horn
2020-10-07 12:36 ` Christoph Hellwig
2020-10-07 20:15 ` Khalid Aziz [this message]
2020-10-07 12:35 ` [PATCH 1/2] mm/mprotect: Call arch_validate_prot under mmap_lock and with length Christoph Hellwig
2020-10-07 14:42 ` Jann Horn
2020-10-08 6:21 ` Christoph Hellwig
2020-10-08 10:34 ` Michael Ellerman
2020-10-08 11:03 ` Catalin Marinas
2020-10-07 20:14 ` Khalid Aziz
2020-10-10 11:09 ` Catalin Marinas
2020-10-12 17:03 ` Khalid Aziz
2020-10-12 17:22 ` Catalin Marinas
2020-10-12 19:14 ` Khalid Aziz
2020-10-13 9:16 ` Catalin Marinas
2020-10-14 21:21 ` Khalid Aziz
2020-10-14 22:29 ` Jann Horn
2020-10-15 9:05 ` Catalin Marinas
2020-10-15 14:53 ` Khalid Aziz
2020-10-08 10:12 ` Catalin Marinas
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