Messages in this thread Patch in this message | | | From | Hsin-Yi Wang <> | Date | Thu, 29 Aug 2019 18:03:57 +0800 | Subject | Re: [PATCH v9 2/3] fdt: add support for rng-seed |
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On Thu, Aug 29, 2019 at 1:36 AM Kees Cook <keescook@chromium.org> wrote: > > Can this please be a boot param (with the default controlled by the > CONFIG)? See how CONFIG_RANDOM_TRUST_CPU is wired up... > > -Kees >
Currently rng-seed read and added in setup_arch() --> setup_machine_fdt().. -> early_init_dt_scan_chosen(), which is earlier than parse_early_param() that initializes early_param.
If we want to set it as a boot param, add_bootloader_randomness() can only be called after parse_early_param(). The seed can't be directly added to pool after it's read in. We need to store into global variable and load it later. If this seems okay then I'll add a patch for this. Thanks
--- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -1096,13 +1096,15 @@ static const char *config_cmdline = CONFIG_CMDLINE;
+const void* rng_seed; +int rng_seed_len; + int __init early_init_dt_scan_chosen(unsigned long node, const char *uname, int depth, void *data) { int l = 0; const char *p = NULL; char *cmdline = data; - const void *rng_seed;
pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
@@ -1137,10 +1139,8 @@ 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) { - add_bootloader_randomness(rng_seed, l); // Originally it's added to entropy pool here - + rng_seed = of_get_flat_dt_prop(node, "rng-seed", &rng_seed_len); + if (rng_seed && rng_seed_len > 0) { /* try to clear seed so it won't be found. */
diff --git a/include/linux/random.h b/include/linux/random.h index 831a002a1882..946840bba7c1 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -31,6 +31,15 @@ static inline void add_latent_entropy(void) static inline void add_latent_entropy(void) {} #endif
+extern const void* rng_seed; +extern int rng_seed_len; + +static inline void add_bootloader_entropy(void) +{ + if (rng_seed && rng_seed_len > 0) + add_bootloader_randomness(rng_seed, rng_seed_len); +} + extern void add_input_randomness(unsigned int type, unsigned int code, unsigned int value) __latent_entropy; extern void add_interrupt_randomness(int irq, int irq_flags) __latent_entropy; diff --git a/init/main.c b/init/main.c index 71847af32e4e..f74a8c7b34af 100644 --- a/init/main.c +++ b/init/main.c @@ -645,6 +645,7 @@ asmlinkage __visible void __init start_kernel(void) * - adding command line entropy */ rand_initialize(); + add_bootloader_entropy(); add_latent_entropy(); add_device_randomness(command_line, strlen(command_line)); boot_init_stack_canary();
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