| Message ID | 20190513003819.356-1-hsinyi@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/2] fdt: add support for rng-seed | expand |
On Mon, May 13, 2019 at 08:38:18AM +0800, Hsin-Yi Wang wrote: > Introducing a chosen node, rng-seed, which is an entropy that can be > passed to kernel called very early to increase initial device > randomness. Bootloader should provide this entropy and the value is > read from /chosen/rng-seed in DT. > > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> > --- > change log: > v1->v2: > * call function in early_init_dt_scan_chosen > * will add doc to devicetree-org/dt-schema on github if this is accepted > --- > Documentation/devicetree/bindings/chosen.txt | 14 ++++++++++++++ > drivers/of/fdt.c | 11 +++++++++++ > 2 files changed, 25 insertions(+) > > diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt > index 45e79172a646..fef5c82672dc 100644 > --- a/Documentation/devicetree/bindings/chosen.txt > +++ b/Documentation/devicetree/bindings/chosen.txt > @@ -28,6 +28,20 @@ mode) when EFI_RNG_PROTOCOL is supported, it will be overwritten by > the Linux EFI stub (which will populate the property itself, using > EFI_RNG_PROTOCOL). > > +rng-seed > +----------- > + > +This property served as an entropy to add device randomness. It is parsed > +as a byte array, e.g. > + > +/ { > + chosen { > + rng-seed = <0x31 0x95 0x1b 0x3c 0xc9 0xfa 0xb3 ...>; > + }; > +}; > + > +This random value should be provided by bootloader. > + > stdout-path > ----------- > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index de893c9616a1..96ea5eba9dd5 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -24,6 +24,7 @@ > #include <linux/debugfs.h> > #include <linux/serial_core.h> > #include <linux/sysfs.h> > +#include <linux/random.h> > > #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ > #include <asm/page.h> > @@ -1079,6 +1080,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, > { > int l; > const char *p; > + const void *rng_seed; > > pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname); > > @@ -1113,6 +1115,15 @@ 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) > + return 1; > + > + /* try to clear seed so it won't be found. */ > + fdt_nop_property(initial_boot_params, node, "rng-seed"); > + > + add_device_randomness(rng_seed, l); Please fix the indentation. > + > /* break now */ > return 1; > } > -- > 2.20.1 >
On Sun, May 12, 2019 at 7:39 PM Hsin-Yi Wang <hsinyi@chromium.org> wrote: > > Introducing a chosen node, rng-seed, which is an entropy that can be > passed to kernel called very early to increase initial device > randomness. Bootloader should provide this entropy and the value is > read from /chosen/rng-seed in DT. > > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> > --- > change log: > v1->v2: > * call function in early_init_dt_scan_chosen > * will add doc to devicetree-org/dt-schema on github if this is accepted > --- > Documentation/devicetree/bindings/chosen.txt | 14 ++++++++++++++ > drivers/of/fdt.c | 11 +++++++++++ > 2 files changed, 25 insertions(+) > > diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt > index 45e79172a646..fef5c82672dc 100644 > --- a/Documentation/devicetree/bindings/chosen.txt > +++ b/Documentation/devicetree/bindings/chosen.txt > @@ -28,6 +28,20 @@ mode) when EFI_RNG_PROTOCOL is supported, it will be overwritten by > the Linux EFI stub (which will populate the property itself, using > EFI_RNG_PROTOCOL). > > +rng-seed > +----------- > + > +This property served as an entropy to add device randomness. It is parsed > +as a byte array, e.g. > + > +/ { > + chosen { > + rng-seed = <0x31 0x95 0x1b 0x3c 0xc9 0xfa 0xb3 ...>; > + }; > +}; > + > +This random value should be provided by bootloader. > + > stdout-path > ----------- > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index de893c9616a1..96ea5eba9dd5 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -24,6 +24,7 @@ > #include <linux/debugfs.h> > #include <linux/serial_core.h> > #include <linux/sysfs.h> > +#include <linux/random.h> > > #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ > #include <asm/page.h> > @@ -1079,6 +1080,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, > { > int l; > const char *p; > + const void *rng_seed; > > pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname); > > @@ -1113,6 +1115,15 @@ 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) > + return 1; This only works if this hunk stays at the end of the function. I'd invert the if and move the next 2 functions under it. > + > + /* try to clear seed so it won't be found. */ > + fdt_nop_property(initial_boot_params, node, "rng-seed"); I'd just delete the property. Also, what about kexec? Don't you need to add a new seed? > + > + add_device_randomness(rng_seed, l); > + > /* break now */ > return 1; > } > -- > 2.20.1 >
On Mon, May 13, 2019 at 9:14 PM Rob Herring <robh+dt@kernel.org> wrote: > > + fdt_nop_property(initial_boot_params, node, "rng-seed"); > > I'd just delete the property. > > Also, what about kexec? Don't you need to add a new seed? > Will update in v3. Thanks.
diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt index 45e79172a646..fef5c82672dc 100644 --- a/Documentation/devicetree/bindings/chosen.txt +++ b/Documentation/devicetree/bindings/chosen.txt @@ -28,6 +28,20 @@ mode) when EFI_RNG_PROTOCOL is supported, it will be overwritten by the Linux EFI stub (which will populate the property itself, using EFI_RNG_PROTOCOL). +rng-seed +----------- + +This property served as an entropy to add device randomness. It is parsed +as a byte array, e.g. + +/ { + chosen { + rng-seed = <0x31 0x95 0x1b 0x3c 0xc9 0xfa 0xb3 ...>; + }; +}; + +This random value should be provided by bootloader. + stdout-path ----------- diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index de893c9616a1..96ea5eba9dd5 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -24,6 +24,7 @@ #include <linux/debugfs.h> #include <linux/serial_core.h> #include <linux/sysfs.h> +#include <linux/random.h> #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ #include <asm/page.h> @@ -1079,6 +1080,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, { int l; const char *p; + const void *rng_seed; pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname); @@ -1113,6 +1115,15 @@ 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) + return 1; + + /* try to clear seed so it won't be found. */ + fdt_nop_property(initial_boot_params, node, "rng-seed"); + + add_device_randomness(rng_seed, l); + /* break now */ return 1; }
Introducing a chosen node, rng-seed, which is an entropy that can be passed to kernel called very early to increase initial device randomness. Bootloader should provide this entropy and the value is read from /chosen/rng-seed in DT. Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org> --- change log: v1->v2: * call function in early_init_dt_scan_chosen * will add doc to devicetree-org/dt-schema on github if this is accepted --- Documentation/devicetree/bindings/chosen.txt | 14 ++++++++++++++ drivers/of/fdt.c | 11 +++++++++++ 2 files changed, 25 insertions(+)