From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [Query] ARM64 kaslr support - randomness, seeding and kdump
Date: Wed, 18 Apr 2018 12:52:26 +0100 [thread overview]
Message-ID: <20180418115225.7hvhsua25rhfqvjs@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <CACi5LpNKbSejFecV+G8X53t4VDwsTvJywWLgLVw9qsD7u6REvg@mail.gmail.com>
On Sun, Apr 15, 2018 at 01:44:16AM +0530, Bhupesh Sharma wrote:
> 4. Accordingly, I wanted to get opinions on whether arm64 timer count is a good
> entropy source on platforms which indeed support EFI_RNG_PROTOCOL?
On its own, the timer is not a good entropy source.
If we have the EFI_RNG_PROTOCOL, we can use that directly.
> And whether we should be looking to extend 'arch_get_random_*' or
> 'random_get_entropy' for arm64, to provide seed/entropy using APIs
> like 'efi_random_get_seed'?
The EFI RNG protocol is only available during boot services, so we can't
call this during the usual operation of the kernel. The seed the stub
generates into the RNG table is already thrown into the entropy pool by
efi_config_parse_tables(). Look for LINUX_EFI_RANDOM_SEED_TABLE_GUID.
So any attemps to acquire a random number via the usual APIs will in
part be affects by this entropy, and nothing needs to be done to
arch_get_random_* to use this entropy.
Thanks,
Mark.
WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Bhupesh Sharma <bhsharma@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>,
Bhupesh SHARMA <bhupesh.linux@gmail.com>,
kexec@lists.infradead.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [Query] ARM64 kaslr support - randomness, seeding and kdump
Date: Wed, 18 Apr 2018 12:52:26 +0100 [thread overview]
Message-ID: <20180418115225.7hvhsua25rhfqvjs@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <CACi5LpNKbSejFecV+G8X53t4VDwsTvJywWLgLVw9qsD7u6REvg@mail.gmail.com>
On Sun, Apr 15, 2018 at 01:44:16AM +0530, Bhupesh Sharma wrote:
> 4. Accordingly, I wanted to get opinions on whether arm64 timer count is a good
> entropy source on platforms which indeed support EFI_RNG_PROTOCOL?
On its own, the timer is not a good entropy source.
If we have the EFI_RNG_PROTOCOL, we can use that directly.
> And whether we should be looking to extend 'arch_get_random_*' or
> 'random_get_entropy' for arm64, to provide seed/entropy using APIs
> like 'efi_random_get_seed'?
The EFI RNG protocol is only available during boot services, so we can't
call this during the usual operation of the kernel. The seed the stub
generates into the RNG table is already thrown into the entropy pool by
efi_config_parse_tables(). Look for LINUX_EFI_RANDOM_SEED_TABLE_GUID.
So any attemps to acquire a random number via the usual APIs will in
part be affects by this entropy, and nothing needs to be done to
arch_get_random_* to use this entropy.
Thanks,
Mark.
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next prev parent reply other threads:[~2018-04-18 11:52 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-12 20:14 [Query] ARM64 kaslr support - randomness, seeding and kdump Bhupesh Sharma
2018-03-12 20:14 ` Bhupesh Sharma
2018-03-12 20:58 ` Ard Biesheuvel
2018-03-12 20:58 ` Ard Biesheuvel
2018-03-13 1:54 ` Dave Young
2018-03-13 1:54 ` Dave Young
2018-03-13 10:22 ` AKASHI Takahiro
2018-03-13 10:22 ` AKASHI Takahiro
2018-03-13 10:47 ` Mark Rutland
2018-03-13 10:47 ` Mark Rutland
2018-03-13 11:07 ` AKASHI Takahiro
2018-03-13 11:07 ` AKASHI Takahiro
2018-03-13 11:20 ` Mark Rutland
2018-03-13 11:20 ` Mark Rutland
2018-03-13 19:48 ` Bhupesh Sharma
2018-03-13 19:48 ` Bhupesh Sharma
2018-03-14 2:10 ` AKASHI Takahiro
2018-03-14 2:10 ` AKASHI Takahiro
2018-03-14 5:03 ` Bhupesh Sharma
2018-03-14 5:03 ` Bhupesh Sharma
2018-03-14 6:40 ` AKASHI Takahiro
2018-03-14 6:40 ` AKASHI Takahiro
2018-03-14 18:24 ` Mark Rutland
2018-03-14 18:24 ` Mark Rutland
2018-03-16 9:35 ` Bhupesh Sharma
2018-03-16 9:35 ` Bhupesh Sharma
2018-04-06 2:09 ` AKASHI Takahiro
2018-04-06 2:09 ` AKASHI Takahiro
2018-04-09 4:01 ` Bhupesh Sharma
2018-04-09 4:01 ` Bhupesh Sharma
2018-04-09 4:31 ` AKASHI Takahiro
2018-04-09 4:31 ` AKASHI Takahiro
2018-04-09 9:28 ` Ard Biesheuvel
2018-04-09 9:28 ` Ard Biesheuvel
2018-04-09 9:39 ` Baoquan He
2018-04-09 9:39 ` Baoquan He
2018-04-09 18:28 ` Bhupesh Sharma
2018-04-09 18:28 ` Bhupesh Sharma
2018-04-10 0:47 ` AKASHI Takahiro
2018-04-10 0:47 ` AKASHI Takahiro
2018-04-14 20:14 ` Bhupesh Sharma
2018-04-14 20:14 ` Bhupesh Sharma
2018-04-18 11:52 ` Mark Rutland [this message]
2018-04-18 11:52 ` Mark Rutland
2018-04-23 20:34 ` Bhupesh Sharma
2018-04-23 20:34 ` Bhupesh Sharma
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