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[PATCH v2 1/8] device-tree: add re-randomization helper function

Jason A. Donenfeld posted 8 patches 3 years, 4 months ago
Maintainers: "Cédric Le Goater" <clg@kaod.org>, Peter Maydell <peter.maydell@linaro.org>, Andrew Jeffery <andrew@aj.id.au>, Joel Stanley <joel@jms.id.au>, Richard Henderson <richard.henderson@linaro.org>, Helge Deller <deller@gmx.de>, Sergio Lopez <slp@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Eduardo Habkost <eduardo@habkost.net>, Paul Burton <paulburton@kernel.org>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, "Philippe Mathieu-Daudé" <f4bug@amsat.org>, Stafford Horne <shorne@gmail.com>, BALATON Zoltan <balaton@eik.bme.hu>, Daniel Henrique Barboza <danielhb413@gmail.com>, David Gibson <david@gibson.dropbear.id.au>, Greg Kurz <groug@kaod.org>, Palmer Dabbelt <palmer@dabbelt.com>, Alistair Francis <alistair.francis@wdc.com>, Bin Meng <bin.meng@windriver.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, David Hildenbrand <david@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>, Yanan Wang <wangyanan55@huawei.com>, Juan Quintela <quintela@redhat.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>
There is a newer version of this series
[PATCH v2 1/8] device-tree: add re-randomization helper function
Posted by Jason A. Donenfeld 3 years, 4 months ago 
When the system reboots, the rng-seed that the FDT has should be
re-randomized, so that the new boot gets a new seed. Several
architectures require this functionality, so export a function for
injecting a new seed into the given FDT.

Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 include/sysemu/device_tree.h |  9 +++++++++
 softmmu/device_tree.c        | 21 +++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index ef060a9759..d552f324b6 100644
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -196,6 +196,15 @@ int qemu_fdt_setprop_sized_cells_from_array(void *fdt,
                                                 qdt_tmp);                 \
     })
 
+
+/**
+ * qemu_fdt_randomize_seeds:
+ * @fdt: device tree blob
+ *
+ * Re-randomize all "rng-seed" properties with new seeds.
+ */
+void qemu_fdt_randomize_seeds(void *fdt);
+
 #define FDT_PCI_RANGE_RELOCATABLE          0x80000000
 #define FDT_PCI_RANGE_PREFETCHABLE         0x40000000
 #define FDT_PCI_RANGE_ALIASED              0x20000000
diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
index 6ca3fad285..d986c7b7b3 100644
--- a/softmmu/device_tree.c
+++ b/softmmu/device_tree.c
@@ -22,6 +22,7 @@
 #include "qemu/option.h"
 #include "qemu/bswap.h"
 #include "qemu/cutils.h"
+#include "qemu/guest-random.h"
 #include "sysemu/device_tree.h"
 #include "hw/loader.h"
 #include "hw/boards.h"
@@ -643,3 +644,23 @@ out:
     g_free(propcells);
     return ret;
 }
+
+void qemu_fdt_randomize_seeds(void *fdt)
+{
+    int noffset, poffset, len;
+    const char *name;
+    uint8_t *data;
+
+    for (noffset = fdt_next_node(fdt, 0, NULL);
+         noffset >= 0;
+         noffset = fdt_next_node(fdt, noffset, NULL)) {
+        for (poffset = fdt_first_property_offset(fdt, noffset);
+             poffset >= 0;
+             poffset = fdt_next_property_offset(fdt, poffset)) {
+            data = (uint8_t *)fdt_getprop_by_offset(fdt, poffset, &name, &len);
+            if (!data || strcmp(name, "rng-seed"))
+                continue;
+            qemu_guest_getrandom_nofail(data, len);
+        }
+    }
+}
-- 
2.37.3
Re: [PATCH v2 1/8] device-tree: add re-randomization helper function
Posted by Alistair Francis 3 years, 4 months ago 
On Wed, Oct 12, 2022 at 6:57 AM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> When the system reboots, the rng-seed that the FDT has should be
> re-randomized, so that the new boot gets a new seed. Several
> architectures require this functionality, so export a function for
> injecting a new seed into the given FDT.
>
> Cc: Alistair Francis <alistair.francis@wdc.com>
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  include/sysemu/device_tree.h |  9 +++++++++
>  softmmu/device_tree.c        | 21 +++++++++++++++++++++
>  2 files changed, 30 insertions(+)
>
> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
> index ef060a9759..d552f324b6 100644
> --- a/include/sysemu/device_tree.h
> +++ b/include/sysemu/device_tree.h
> @@ -196,6 +196,15 @@ int qemu_fdt_setprop_sized_cells_from_array(void *fdt,
>                                                  qdt_tmp);                 \
>      })
>
> +
> +/**
> + * qemu_fdt_randomize_seeds:
> + * @fdt: device tree blob
> + *
> + * Re-randomize all "rng-seed" properties with new seeds.
> + */
> +void qemu_fdt_randomize_seeds(void *fdt);
> +
>  #define FDT_PCI_RANGE_RELOCATABLE          0x80000000
>  #define FDT_PCI_RANGE_PREFETCHABLE         0x40000000
>  #define FDT_PCI_RANGE_ALIASED              0x20000000
> diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
> index 6ca3fad285..d986c7b7b3 100644
> --- a/softmmu/device_tree.c
> +++ b/softmmu/device_tree.c
> @@ -22,6 +22,7 @@
>  #include "qemu/option.h"
>  #include "qemu/bswap.h"
>  #include "qemu/cutils.h"
> +#include "qemu/guest-random.h"
>  #include "sysemu/device_tree.h"
>  #include "hw/loader.h"
>  #include "hw/boards.h"
> @@ -643,3 +644,23 @@ out:
>      g_free(propcells);
>      return ret;
>  }
> +
> +void qemu_fdt_randomize_seeds(void *fdt)
> +{
> +    int noffset, poffset, len;
> +    const char *name;
> +    uint8_t *data;
> +
> +    for (noffset = fdt_next_node(fdt, 0, NULL);
> +         noffset >= 0;
> +         noffset = fdt_next_node(fdt, noffset, NULL)) {
> +        for (poffset = fdt_first_property_offset(fdt, noffset);
> +             poffset >= 0;
> +             poffset = fdt_next_property_offset(fdt, poffset)) {
> +            data = (uint8_t *)fdt_getprop_by_offset(fdt, poffset, &name, &len);
> +            if (!data || strcmp(name, "rng-seed"))
> +                continue;
> +            qemu_guest_getrandom_nofail(data, len);
> +        }
> +    }
> +}
> --
> 2.37.3
>
>

Patchew 2.1-devel-b67e4c2

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