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From: Andrew Morton <akpm@linux-foundation.org>
To: Daniel Cashman <dcashman@android.com>
Cc: linux-kernel@vger.kernel.org, linux@arm.linux.org.uk,
	keescook@chromium.org, mingo@kernel.org,
	linux-arm-kernel@lists.infradead.org, corbet@lwn.net,
	dzickus@redhat.com, ebiederm@xmission.com, xypron.glpk@gmx.de,
	jpoimboe@redhat.com, kirill.shutemov@linux.intel.com,
	n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, mgorman@suse.de,
	tglx@linutronix.de, rientjes@google.com, linux-mm@kvack.org,
	linux-doc@vger.kernel.org, salyzyn@android.com, jeffv@google.com,
	nnk@google.com, catalin.marinas@arm.com, will.deacon@arm.com,
	hpa@zytor.com, x86@kernel.org, hecmargi@upv.es, bp@suse.de,
	dcashman@google.com
Subject: Re: [PATCH v4 1/4] mm: mmap: Add new /proc tunable for mmap_base ASLR.
Date: Mon, 30 Nov 2015 15:54:12 -0800	[thread overview]
Message-ID: <20151130155412.b1a087f4f6f4d4180ab4472d@linux-foundation.org> (raw)
In-Reply-To: <1448578785-17656-2-git-send-email-dcashman@android.com>

On Thu, 26 Nov 2015 14:59:42 -0800 Daniel Cashman <dcashman@android.com> wrote:

> ASLR  only uses as few as 8 bits to generate the random offset for the
> mmap base address on 32 bit architectures. This value was chosen to
> prevent a poorly chosen value from dividing the address space in such
> a way as to prevent large allocations. This may not be an issue on all
> platforms. Allow the specification of a minimum number of bits so that
> platforms desiring greater ASLR protection may determine where to place
> the trade-off.
> 
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1568,6 +1568,28 @@ static struct ctl_table vm_table[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_doulongvec_minmax,
>  	},
> +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
> +	{
> +		.procname	= "mmap_rnd_bits",
> +		.data		= &mmap_rnd_bits,
> +		.maxlen		= sizeof(mmap_rnd_bits),
> +		.mode		= 0600,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= (void *) &mmap_rnd_bits_min,
> +		.extra2		= (void *) &mmap_rnd_bits_max,

hm, why the typecasts?  They're unneeded and are omitted everywhere(?)
else in kernel/sysctl.c.



WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: Daniel Cashman <dcashman@android.com>
Cc: linux-kernel@vger.kernel.org, linux@arm.linux.org.uk,
	keescook@chromium.org, mingo@kernel.org,
	linux-arm-kernel@lists.infradead.org, corbet@lwn.net,
	dzickus@redhat.com, ebiederm@xmission.com, xypron.glpk@gmx.de,
	jpoimboe@redhat.com, kirill.shutemov@linux.intel.com,
	n-horiguchi@ah.jp.nec.com, aarcange@redhat.com, mgorman@suse.de,
	tglx@linutronix.de, rientjes@google.com, linux-mm@kvack.org,
	linux-doc@vger.kernel.org, salyzyn@android.com, jeffv@google.com,
	nnk@google.com, catalin.marinas@arm.com, will.deacon@arm.com,
	hpa@zytor.com, x86@kernel.org, hecmargi@upv.es, bp@suse.de,
	dcashman@google.com
Subject: Re: [PATCH v4 1/4] mm: mmap: Add new /proc tunable for mmap_base ASLR.
Date: Mon, 30 Nov 2015 15:54:12 -0800	[thread overview]
Message-ID: <20151130155412.b1a087f4f6f4d4180ab4472d@linux-foundation.org> (raw)
In-Reply-To: <1448578785-17656-2-git-send-email-dcashman@android.com>

On Thu, 26 Nov 2015 14:59:42 -0800 Daniel Cashman <dcashman@android.com> wrote:

> ASLR  only uses as few as 8 bits to generate the random offset for the
> mmap base address on 32 bit architectures. This value was chosen to
> prevent a poorly chosen value from dividing the address space in such
> a way as to prevent large allocations. This may not be an issue on all
> platforms. Allow the specification of a minimum number of bits so that
> platforms desiring greater ASLR protection may determine where to place
> the trade-off.
> 
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1568,6 +1568,28 @@ static struct ctl_table vm_table[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_doulongvec_minmax,
>  	},
> +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
> +	{
> +		.procname	= "mmap_rnd_bits",
> +		.data		= &mmap_rnd_bits,
> +		.maxlen		= sizeof(mmap_rnd_bits),
> +		.mode		= 0600,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= (void *) &mmap_rnd_bits_min,
> +		.extra2		= (void *) &mmap_rnd_bits_max,

hm, why the typecasts?  They're unneeded and are omitted everywhere(?)
else in kernel/sysctl.c.


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WARNING: multiple messages have this Message-ID (diff)
From: akpm@linux-foundation.org (Andrew Morton)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 1/4] mm: mmap: Add new /proc tunable for mmap_base ASLR.
Date: Mon, 30 Nov 2015 15:54:12 -0800	[thread overview]
Message-ID: <20151130155412.b1a087f4f6f4d4180ab4472d@linux-foundation.org> (raw)
In-Reply-To: <1448578785-17656-2-git-send-email-dcashman@android.com>

On Thu, 26 Nov 2015 14:59:42 -0800 Daniel Cashman <dcashman@android.com> wrote:

> ASLR  only uses as few as 8 bits to generate the random offset for the
> mmap base address on 32 bit architectures. This value was chosen to
> prevent a poorly chosen value from dividing the address space in such
> a way as to prevent large allocations. This may not be an issue on all
> platforms. Allow the specification of a minimum number of bits so that
> platforms desiring greater ASLR protection may determine where to place
> the trade-off.
> 
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1568,6 +1568,28 @@ static struct ctl_table vm_table[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_doulongvec_minmax,
>  	},
> +#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
> +	{
> +		.procname	= "mmap_rnd_bits",
> +		.data		= &mmap_rnd_bits,
> +		.maxlen		= sizeof(mmap_rnd_bits),
> +		.mode		= 0600,
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= (void *) &mmap_rnd_bits_min,
> +		.extra2		= (void *) &mmap_rnd_bits_max,

hm, why the typecasts?  They're unneeded and are omitted everywhere(?)
else in kernel/sysctl.c.

  parent reply	other threads:[~2015-11-30 23:54 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-26 22:59 [PATCH v4 0/4] Allow customizable random offset to mmap_base address Daniel Cashman
2015-11-26 22:59 ` Daniel Cashman
2015-11-26 22:59 ` Daniel Cashman
2015-11-26 22:59 ` [PATCH v4 1/4] mm: mmap: Add new /proc tunable for mmap_base ASLR Daniel Cashman
2015-11-26 22:59   ` Daniel Cashman
2015-11-26 22:59   ` Daniel Cashman
2015-11-26 22:59   ` [PATCH v4 2/4] arm: mm: support ARCH_MMAP_RND_BITS Daniel Cashman
2015-11-26 22:59     ` Daniel Cashman
2015-11-26 22:59     ` Daniel Cashman
2015-11-26 22:59     ` [PATCH v4 3/4] arm64: " Daniel Cashman
2015-11-26 22:59       ` Daniel Cashman
2015-11-26 22:59       ` Daniel Cashman
2015-11-26 22:59       ` [PATCH v4 4/4] x86: " Daniel Cashman
2015-11-26 22:59         ` Daniel Cashman
2015-11-26 22:59         ` Daniel Cashman
2015-12-01  0:03         ` Kees Cook
2015-12-01  0:03           ` Kees Cook
2015-12-01  0:03           ` Kees Cook
2015-12-01 18:19           ` Daniel Cashman
2015-12-01 18:19             ` Daniel Cashman
2015-12-01 18:19             ` Daniel Cashman
2015-11-30 23:54   ` Andrew Morton [this message]
2015-11-30 23:54     ` [PATCH v4 1/4] mm: mmap: Add new /proc tunable for mmap_base ASLR Andrew Morton
2015-11-30 23:54     ` Andrew Morton
2015-12-01  0:01     ` Andrew Morton
2015-12-01  0:01       ` Andrew Morton
2015-12-01  0:01       ` Andrew Morton
2015-12-01  0:04       ` Kees Cook
2015-12-01  0:04         ` Kees Cook
2015-12-01  0:04         ` Kees Cook
2015-12-01  0:18         ` Andrew Morton
2015-12-01  0:18           ` Andrew Morton
2015-12-01  0:18           ` Andrew Morton
2015-12-01  0:47           ` Daniel Cashman
2015-12-01  0:47             ` Daniel Cashman
2015-12-01  0:47             ` Daniel Cashman
2015-12-01  0:55           ` Eric W. Biederman
2015-12-01  0:55             ` Eric W. Biederman
2015-12-01  0:55             ` Eric W. Biederman
2015-12-01 22:09             ` Andrew Morton
2015-12-01 22:09               ` Andrew Morton
2015-12-01 22:09               ` Andrew Morton
2015-12-01  1:00           ` Kees Cook
2015-12-01  1:00             ` Kees Cook
2015-12-01  1:00             ` Kees Cook
2015-12-01  0:05   ` Kees Cook
2015-12-01  0:05     ` Kees Cook
2015-12-01  0:05     ` Kees Cook
2015-11-26 23:24 ` [PATCH v4 0/4] Allow customizable random offset to mmap_base address Daniel Cashman
2015-11-26 23:24   ` Daniel Cashman
2015-11-26 23:24   ` Daniel Cashman

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