From: Kees Cook <keescook@chromium.org>
To: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Mukesh Ojha <mojha@codeaurora.org>,
Grzegorz Halat <ghalat@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Guenter Roeck <groeck@chromium.org>,
Will Deacon <will@kernel.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Rob Herring <robh@kernel.org>,
Daniel Thompson <daniel.thompson@linaro.org>,
Anders Roxell <anders.roxell@linaro.org>,
Yury Norov <ynorov@marvell.com>, Marc Zyngier <maz@kernel.org>,
Russell King <linux@armlinux.org.uk>,
Aaro Koskinen <aaro.koskinen@nokia.com>,
Ingo Molnar <mingo@redhat.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Waiman Long <longman@redhat.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Wei Li <liwei391@huawei.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Len Brown <len.brown@intel.com>, Arnd Bergmann <arnd@arndb.de>,
Rik van Riel <riel@surriel.com>,
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Shaokun Zhang <zhangshaokun@hisilicon.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Borislav Petkov <bp@alien8.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
"Theodore Y . Ts'o" <tytso@mit.edu>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
lkml <linux-kernel@vger.kernel.org>,
Armijn Hemel <armijn@tjaldur.nl>, Jiri Kosina <jkosina@suse.cz>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH v9 2/3] fdt: add support for rng-seed
Date: Thu, 29 Aug 2019 09:22:28 -0700 [thread overview]
Message-ID: <201908290921.1F0FCC9E5@keescook> (raw)
In-Reply-To: <CAJMQK-iDoPxbFUH3JUeJ7SehCptZOnjKZiUoFd1PqLjDdGHujA@mail.gmail.com>
On Thu, Aug 29, 2019 at 06:03:57PM +0800, Hsin-Yi Wang wrote:
> On Thu, Aug 29, 2019 at 1:36 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > Can this please be a boot param (with the default controlled by the
> > CONFIG)? See how CONFIG_RANDOM_TRUST_CPU is wired up...
> >
> > -Kees
> >
>
> Currently rng-seed read and added in setup_arch() -->
> setup_machine_fdt().. -> early_init_dt_scan_chosen(), which is earlier
> than parse_early_param() that initializes early_param.
>
> If we want to set it as a boot param, add_bootloader_randomness() can
> only be called after parse_early_param(). The seed can't be directly
> added to pool after it's read in. We need to store into global
> variable and load it later.
> If this seems okay then I'll add a patch for this. Thanks
This seems like a good idea to me.
>
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1096,13 +1096,15 @@ static const char *config_cmdline = CONFIG_CMDLINE;
>
> +const void* rng_seed;
> +int rng_seed_len;
These should be __initdata, yes?
> +
> int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
> int depth,
> void *data)
> {
> int l = 0;
> const char *p = NULL;
> char *cmdline = data;
> - const void *rng_seed;
>
> pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
>
> @@ -1137,10 +1139,8 @@ int __init early_init_dt_scan_chosen(unsigned
> long node, const char *uname,
>
> pr_debug("Command line is: %s\n", (char*)data);
>
> - rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
> - if (rng_seed && l > 0) {
> - add_bootloader_randomness(rng_seed, l); //
> Originally it's added to entropy pool here
> -
> + rng_seed = of_get_flat_dt_prop(node, "rng-seed", &rng_seed_len);
> + if (rng_seed && rng_seed_len > 0) {
> /* try to clear seed so it won't be found. */
>
> diff --git a/include/linux/random.h b/include/linux/random.h
> index 831a002a1882..946840bba7c1 100644
> --- a/include/linux/random.h
> +++ b/include/linux/random.h
> @@ -31,6 +31,15 @@ static inline void add_latent_entropy(void)
> static inline void add_latent_entropy(void) {}
> #endif
>
> +extern const void* rng_seed;
> +extern int rng_seed_len;
> +
> +static inline void add_bootloader_entropy(void)
> +{
> + if (rng_seed && rng_seed_len > 0)
> + add_bootloader_randomness(rng_seed, rng_seed_len);
> +}
And this should be __init
> +
> extern void add_input_randomness(unsigned int type, unsigned int code,
> unsigned int value) __latent_entropy;
> extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy;
> diff --git a/init/main.c b/init/main.c
> index 71847af32e4e..f74a8c7b34af 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -645,6 +645,7 @@ asmlinkage __visible void __init start_kernel(void)
> * - adding command line entropy
> */
> rand_initialize();
> + add_bootloader_entropy();
> add_latent_entropy();
> add_device_randomness(command_line, strlen(command_line));
> boot_init_stack_canary();
But yeah, looks reasonable to me.
--
Kees Cook
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next prev parent reply other threads:[~2019-08-29 16:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 7:15 [PATCH v9 0/3] add support for rng-seed Hsin-Yi Wang
2019-08-22 7:15 ` [PATCH v9 1/3] arm64: map FDT as RW for early_init_dt_scan() Hsin-Yi Wang
2019-08-22 7:15 ` [PATCH v9 2/3] fdt: add support for rng-seed Hsin-Yi Wang
2019-08-22 16:03 ` Theodore Y. Ts'o
2019-08-22 17:39 ` Stephen Boyd
2019-08-24 19:04 ` Kees Cook
2019-08-29 10:03 ` Hsin-Yi Wang
2019-08-29 15:45 ` Theodore Y. Ts'o
2019-08-29 16:25 ` Kees Cook
2019-08-29 16:22 ` Kees Cook [this message]
2019-08-22 7:15 ` [PATCH v9 3/3] arm64: kexec_file: add rng-seed support Hsin-Yi Wang
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