diff options
| -rw-r--r-- | drivers/char/Kconfig | 9 | ||||
| -rw-r--r-- | drivers/char/random.c | 14 | ||||
| -rw-r--r-- | drivers/of/fdt.c | 14 | ||||
| -rw-r--r-- | include/linux/random.h | 1 |
4 files changed, 36 insertions, 2 deletions
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig index 3e866885a405..2794f4b3f62d 100644 --- a/drivers/char/Kconfig +++ b/drivers/char/Kconfig @@ -573,3 +573,12 @@ config RANDOM_TRUST_CPU has not installed a hidden back door to compromise the CPU's random number generation facilities. This can also be configured at boot with "random.trust_cpu=on/off". + +config RANDOM_TRUST_BOOTLOADER + bool "Trust the bootloader to initialize Linux's CRNG" + help + Some bootloaders can provide entropy to increase the kernel's initial + device randomness. Say Y here to assume the entropy provided by the + booloader is trustworthy so it will be added to the kernel's entropy + pool. Otherwise, say N here so it will be regarded as device input that + only mixes the entropy pool.
\ No newline at end of file diff --git a/drivers/char/random.c b/drivers/char/random.c index 5d5ea4ce1442..566922df4b7b 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -2445,3 +2445,17 @@ void add_hwgenerator_randomness(const char *buffer, size_t count, credit_entropy_bits(poolp, entropy); } EXPORT_SYMBOL_GPL(add_hwgenerator_randomness); + +/* Handle random seed passed by bootloader. + * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise + * it would be regarded as device data. + * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER. + */ +void add_bootloader_randomness(const void *buf, unsigned int size) +{ + if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER)) + add_hwgenerator_randomness(buf, size, size * 8); + else + add_device_randomness(buf, size); +} +EXPORT_SYMBOL_GPL(add_bootloader_randomness);
\ No newline at end of file diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index 9cdf14b9aaab..7d97ab6d0e31 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> @@ -1044,6 +1045,7 @@ 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); @@ -1078,6 +1080,14 @@ 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); + + /* try to clear seed so it won't be found. */ + fdt_nop_property(initial_boot_params, node, "rng-seed"); + } + /* break now */ return 1; } @@ -1166,8 +1176,6 @@ bool __init early_init_dt_verify(void *params) /* Setup flat device-tree pointer */ initial_boot_params = params; - of_fdt_crc32 = crc32_be(~0, initial_boot_params, - fdt_totalsize(initial_boot_params)); return true; } @@ -1197,6 +1205,8 @@ bool __init early_init_dt_scan(void *params) return false; early_init_dt_scan_nodes(); + of_fdt_crc32 = crc32_be(~0, initial_boot_params, + fdt_totalsize(initial_boot_params)); return true; } diff --git a/include/linux/random.h b/include/linux/random.h index 1f7dced2bba6..f189c927fdea 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -19,6 +19,7 @@ struct random_ready_callback { }; extern void add_device_randomness(const void *, unsigned int); +extern void add_bootloader_randomness(const void *, unsigned int); #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) static inline void add_latent_entropy(void) |