This patchset creates the DT property /chosen/kaslr-seed which is used by the OS for Address Space Layout Randomization. If the machine is secure, a similar property is created under /secure-chosen.
Changes since v1: - Move creation of /secure-chosen to create_fdt() - Use qemu_guest_getrandom() instead of qcrypto_random_bytes() - Create kaslr-seed for the non-secure OS too
Jerome Forissier (2): hw/arm/virt: dt: move creation of /secure-chosen to create_fdt() hw/arm/virt: dt: add kaslr-seed property
hw/arm/virt.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)
The /secure-chosen node is currently used only by create_uart(), but this will change. Therefore move the creation of this node to create_fdt().
Signed-off-by: Jerome Forissier jerome@forissier.org --- hw/arm/virt.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c index 7dc96abf72c..c3073b7cf19 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -234,6 +234,10 @@ static void create_fdt(VirtMachineState *vms) /* /chosen must exist for load_dtb to fill in necessary properties later */ qemu_fdt_add_subnode(fdt, "/chosen");
+ if (vms->secure) { + qemu_fdt_add_subnode(fdt, "/secure-chosen"); + } + /* Clock node, for the benefit of the UART. The kernel device tree * binding documentation claims the PL011 node clock properties are * optional but in practice if you omit them the kernel refuses to @@ -761,7 +765,6 @@ static void create_uart(const VirtMachineState *vms, int uart, qemu_fdt_setprop_string(vms->fdt, nodename, "status", "disabled"); qemu_fdt_setprop_string(vms->fdt, nodename, "secure-status", "okay");
- qemu_fdt_add_subnode(vms->fdt, "/secure-chosen"); qemu_fdt_setprop_string(vms->fdt, "/secure-chosen", "stdout-path", nodename); }
Generate random seeds to be used by the non-secure and/or secure OSes for ASLR. The seeds are 64-bit random values exported via the DT properties /chosen/kaslr-seed [1] and /secure-chosen/kaslr-seed, the latter being used by OP-TEE [2].
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... [2] https://github.com/OP-TEE/optee_os/commit/ef262691fe0e
Signed-off-by: Jerome Forissier jerome@forissier.org --- hw/arm/virt.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c index c3073b7cf19..1b6f3971bf7 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -77,6 +77,7 @@ #include "hw/acpi/generic_event_device.h" #include "hw/virtio/virtio-iommu.h" #include "hw/char/pl011.h" +#include "qemu/guest-random.h"
#define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \ static void virt_##major##_##minor##_class_init(ObjectClass *oc, \ @@ -213,6 +214,18 @@ static bool cpu_type_valid(const char *cpu) return false; }
+static void create_kaslr_seed(VirtMachineState *vms, const char *node) +{ + Error *err = NULL; + uint64_t seed; + + if (qemu_guest_getrandom(&seed, sizeof(seed), &err)) { + error_free(err); + return; + } + qemu_fdt_setprop_u64(vms->fdt, node, "kaslr-seed", seed); +} + static void create_fdt(VirtMachineState *vms) { MachineState *ms = MACHINE(vms); @@ -233,9 +246,11 @@ static void create_fdt(VirtMachineState *vms)
/* /chosen must exist for load_dtb to fill in necessary properties later */ qemu_fdt_add_subnode(fdt, "/chosen"); + create_kaslr_seed(vms, "/chosen");
if (vms->secure) { qemu_fdt_add_subnode(fdt, "/secure-chosen"); + create_kaslr_seed(vms, "/secure-chosen"); }
/* Clock node, for the benefit of the UART. The kernel device tree
On Mon, 20 Apr 2020 at 13:20, Jerome Forissier jerome@forissier.org wrote:
This patchset creates the DT property /chosen/kaslr-seed which is used by the OS for Address Space Layout Randomization. If the machine is secure, a similar property is created under /secure-chosen.
Changes since v1:
- Move creation of /secure-chosen to create_fdt()
- Use qemu_guest_getrandom() instead of qcrypto_random_bytes()
- Create kaslr-seed for the non-secure OS too
Jerome Forissier (2): hw/arm/virt: dt: move creation of /secure-chosen to create_fdt() hw/arm/virt: dt: add kaslr-seed property
Applied to target-arm.next, thanks.
-- PMM
op-tee@lists.trustedfirmware.org
-
Jerome Forissier -
Peter Maydell