| Message ID | 20221025004327.568476-3-Jason@zx2c4.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | rerandomize RNG seeds on reboot and handle record&replay | expand |
On Tue, Oct 25, 2022 at 10:51 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 e7c5441f56..ca5339beae 100644 > --- a/include/sysemu/device_tree.h > +++ b/include/sysemu/device_tree.h > @@ -197,6 +197,15 @@ 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 ce74f3d48d..30aa3aea9f 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" > @@ -680,3 +681,23 @@ void hmp_dumpdtb(Monitor *mon, const QDict *qdict) > > info_report("dtb dumped to %s", filename); > } > + > +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); > + } > + } > +} > -- > 2.38.1 > >
On 25/10/22 02:43, Jason A. Donenfeld 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> > --- > include/sysemu/device_tree.h | 9 +++++++++ > softmmu/device_tree.c | 21 +++++++++++++++++++++ > 2 files changed, 30 insertions(+) > +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); Is this non-const cast is safe? > + if (!data || strcmp(name, "rng-seed")) > + continue; > + qemu_guest_getrandom_nofail(data, len); Shouldn't we read to the stack and fill with fdt_setprop_inplace()? > + } > + } > +}
On Tue, Oct 25, 2022 at 3:30 PM Philippe Mathieu-Daudé <philmd@linaro.org> wrote: > > On 25/10/22 02:43, Jason A. Donenfeld 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> > > --- > > include/sysemu/device_tree.h | 9 +++++++++ > > softmmu/device_tree.c | 21 +++++++++++++++++++++ > > 2 files changed, 30 insertions(+) > > > +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); > > Is this non-const cast is safe? This is how the libfdt/fdt_rw.c helpers of libfdt do it, so I think so. Jason
diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h index e7c5441f56..ca5339beae 100644 --- a/include/sysemu/device_tree.h +++ b/include/sysemu/device_tree.h @@ -197,6 +197,15 @@ 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 ce74f3d48d..30aa3aea9f 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" @@ -680,3 +681,23 @@ void hmp_dumpdtb(Monitor *mon, const QDict *qdict) info_report("dtb dumped to %s", filename); } + +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); + } + } +}
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(+)