[PATCH 1/2] hwrng: dev-random: always use /dev/urandom

[PATCH 1/2] hwrng: dev-random: always use /dev/urandom

[Ahmad Fatoum]

/dev/random can block long after boot time. It seems there's a consensus
that /dev/urandom is safe to use except for very early boot, which isn't
when barebox sandbox is usually run. To make the HWRNG more useful,
always use /dev/urandom.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/sandbox/board/dev-random.c                | 7 +------
 arch/sandbox/mach-sandbox/include/mach/linux.h | 1 -
 drivers/hw_random/Kconfig                      | 6 +++---
 3 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/sandbox/board/dev-random.c b/arch/sandbox/board/dev-random.c
index f65e5ef6e5ed..60295e9fced2 100644
--- a/arch/sandbox/board/dev-random.c
+++ b/arch/sandbox/board/dev-random.c
@@ -4,10 +4,6 @@
 devrandom_t *devrandom_init(void) {
 	devrandom_t *fds = xzalloc(sizeof(*fds));
 
-	fds->randomfd = linux_open("/dev/random", false);
-	if (fds->randomfd < 0)
-		return ERR_PTR(-EPERM);
-
 	fds->urandomfd = linux_open("/dev/urandom", false);
 	if (fds->urandomfd < 0)
 		return ERR_PTR(-EPERM);
@@ -17,8 +13,7 @@ devrandom_t *devrandom_init(void) {
 
 int devrandom_read(devrandom_t *devrandom, void *buf, size_t len, int wait)
 {
-	if (wait)
-		return linux_read(devrandom->randomfd, buf, len);
+	(void)wait; /* /dev/urandom won't block */
 
 	return linux_read(devrandom->urandomfd, buf, len);
 }
diff --git a/arch/sandbox/mach-sandbox/include/mach/linux.h b/arch/sandbox/mach-sandbox/include/mach/linux.h
index 1e64d41c6a5e..9759a376ecb3 100644
--- a/arch/sandbox/mach-sandbox/include/mach/linux.h
+++ b/arch/sandbox/mach-sandbox/include/mach/linux.h
@@ -52,7 +52,6 @@ int barebox_libftdi1_update(struct ft2232_bitbang *ftbb);
 void barebox_libftdi1_close(void);
 
 typedef struct {
-	int randomfd;
 	int urandomfd;
 } devrandom_t;
 devrandom_t *devrandom_init(void);
diff --git a/drivers/hw_random/Kconfig b/drivers/hw_random/Kconfig
index c57928204d30..242a7ef27828 100644
--- a/drivers/hw_random/Kconfig
+++ b/drivers/hw_random/Kconfig
@@ -15,11 +15,11 @@ config HWRNG_MXC_RNGC
 	  Generator hardware found on some Freescale i.MX processors.
 
 config HWRNG_DEV_RANDOM
-	tristate "Linux /dev/random and /dev/urandom RNG"
+	tristate "Linux /dev/urandom RNG"
 	depends on SANDBOX
 	default y
 	help
-	  This driver allows use of the host provided /dev/random
-	  and /dev/urandom as barebox HWRNGs.
+	  This driver allows use of the host provided /dev/urandom
+	  as barebox HWRNGs.
 
 endif
-- 
2.23.0


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[PATCH 2/2] commands: passwd: suggest sandbox for offline password generation

[Ahmad Fatoum]

Users might want to generate the password while the target is offline.
We don't provide a dedicated host tool for that, but barebox sandbox can
be used. Document this possibility.

While at it, remove a misplaced single quite and slash in the help text.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 commands/Kconfig | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/commands/Kconfig b/commands/Kconfig
index 0189b4715bb9..a6db52ae54b7 100644
--- a/commands/Kconfig
+++ b/commands/Kconfig
@@ -1389,8 +1389,10 @@ config CMD_PASSWD
 	help
 	  Set password
 
-	  'Interactively asks for a password. The digest of this password will be
-	  stored in /env/etc//passwd. This is then used by the 'login' command.
+	  Interactively asks for a password. The digest of this password will be
+	  stored in /env/etc/passwd. This is then used by the 'login' command.
+
+	  Passwords can be generated on the host machine using barebox sandbox.
 
 	  Entering an empty string will disable the password function.
 
-- 
2.23.0


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Re: [PATCH 1/2] hwrng: dev-random: always use /dev/urandom

[Sascha Hauer]

On Mon, Oct 21, 2019 at 02:20:46PM +0200, Ahmad Fatoum wrote:
> /dev/random can block long after boot time. It seems there's a consensus
> that /dev/urandom is safe to use except for very early boot, which isn't
> when barebox sandbox is usually run. To make the HWRNG more useful,
> always use /dev/urandom.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  arch/sandbox/board/dev-random.c                | 7 +------
>  arch/sandbox/mach-sandbox/include/mach/linux.h | 1 -
>  drivers/hw_random/Kconfig                      | 6 +++---
>  3 files changed, 4 insertions(+), 10 deletions(-)

Applied, thanks

Sascha

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