mips: allow firmware to pass RNG seed to kernel
PATCH 1/1 mips: allow firmware to pass RNG seed to kernel
Nearly all other firmware environments have some way of passing a RNG seed to initialize the RNG: DTB's rng-seed, EFI's RNG protocol, m68k's bootinfo block, x86's setup_data, and so forth. This adds something similar for MIPS, which will allow various firmware environments, bootloaders, and hypervisors to pass an RNG seed to initialize the kernel's RNG.
--- arch/mips/kernel/setup.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
arch/mips/kernel/setup.c +21 -0
@@ -42,6 +42,7 @@#include <asm/setup.h> #include <asm/smp-ops.h> #include <asm/prom.h> +#include <asm/fw/fw.h> #ifdef CONFIG_MIPS_ELF_APPENDED_DTB char __section(".appended_dtb") __appended_dtb[0x100000];
@@ -756,6 +757,24 @@ static void __init prefill_possible_map(void)static inline void prefill_possible_map (void ) {}#endif +static void __init setup_rng_seed (void ) +{ +char *rng_seed_hex =fw_getenv ("rngseed" ); +u8 rng_seed[512 ]; +size_t len; + +if (!rng_seed_hex) +return ; + + len =min (sizeof (rng_seed),strlen (rng_seed_hex) /2 ); +if (hex2bin (rng_seed, rng_seed_hex, len)) +return ; + +add_bootloader_randomness (rng_seed, len); +memzero_explicit (rng_seed, len); +memzero_explicit (rng_seed_hex, len *2 ); +} +void __init setup_arch (char **cmdline_p) {cpu_probe ();
@@ -786,6 +805,8 @@ void __init setup_arch(char **cmdline_p)paging_init ();memblock_dump_all (); + +setup_rng_seed (); }unsigned long kernelsp[NR_CPUS ];
Signature · 1 line
2.37.3
Quoted 11 lines · Jason A. Donenfeld
Nearly all other firmware environments have some way of passing a RNG seed to initialize the RNG: DTB's rng-seed, EFI's RNG protocol, m68k's bootinfo block, x86's
setup_data, and so forth. This adds something similar for MIPS, which will allow various firmware environments, bootloaders, and hypervisors to pass an RNG seed to initialize the kernel's RNG.Signed-off-by Jason A. Donenfeld <[email protected]>--- arch/mips/kernel/setup.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)
applied to mips-next.
Thomas.
Signature · 2 lines
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]
Hi Jason,
Quoted 28 lines · Jason A. Donenfeld
Nearly all other firmware environments have some way of passing a RNG seed to initialize the RNG: DTB's rng-seed, EFI's RNG protocol, m68k's bootinfo block, x86's
setup_data, and so forth. This adds something similar for MIPS, which will allow various firmware environments, bootloaders, and hypervisors to pass an RNG seed to initialize the kernel's RNG.Signed-off-by Jason A. Donenfeld <[email protected]>--- arch/mips/kernel/setup.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+)arch/mips/kernel/setup.c +1
-0@@ -42,6 +42,7 @@#include <asm/setup.h> #include <asm/smp-ops.h> #include <asm/prom.h> +#include <asm/fw/fw.h> #ifdef CONFIG_MIPS_ELF_APPENDED_DTB char __section(".appended_dtb") __appended_dtb[0x100000];@@ -756,6 +757,24 @@ static void __init prefill_possible_map(void)static inline void prefill_possible_map (void ) {}#endif
arch/mips/kernel/setup.c static void __init prefill_possible_map(void) · line 768
Quoted 10 lines
arch/mips/kernel/setup.c +9
-0+static void __init setup_rng_seed (void ) +{ +char *rng_seed_hex =fw_getenv ("rngseed" ); +u8 rng_seed[512 ]; +size_t len; + +if (!rng_seed_hex) +return ; +
Assuming rngseed="x", ...
arch/mips/kernel/setup.c static void __init prefill_possible_map(void) · line 769
Quoted 1 line
arch/mips/kernel/setup.c +1
-0+ len =min (sizeof (rng_seed),strlen (rng_seed_hex) /2 );
... len = 0 ...
arch/mips/kernel/setup.c static void __init prefill_possible_map(void) · line 771
Quoted 2 lines
arch/mips/kernel/setup.c +2
-0+if (hex2bin (rng_seed, rng_seed_hex, len)) +return ;
hex2bin(..., len=0) = 0
arch/mips/kernel/setup.c static void __init prefill_possible_map(void) · line 773
Quoted 2 lines
arch/mips/kernel/setup.c +2
-0+ +add_bootloader_randomness (rng_seed, len);
So we call char/random code with len=0. Is it safe? Maybe simply safer to check len before calling hex2bin?
Quoted 19 lines
arch/mips/kernel/setup.c +6
-1+memzero_explicit (rng_seed, len); +memzero_explicit (rng_seed_hex, len *2 ); +} +void __init setup_arch (char **cmdline_p) {cpu_probe ();@@ -786,6 +805,8 @@ void __init setup_arch(char **cmdline_p)paging_init ();memblock_dump_all (); + +setup_rng_seed (); }unsigned long kernelsp[NR_CPUS ]; --2.37.3
Hi Philippe,
Quoted 4 lines · Philippe Mathieu-Daudé
Quoted 1 line
+
add_bootloader_randomness(rng_seed, len);So we call char/random code with len=0. Is it safe? Maybe simply safer to check len before calling hex2bin?
add_bootloader_randomness() is safe for all input sizes, and is written to be callable with len=0 and have no effect. So this function should be good as-is; there's no need to special case an unlikely instance that's already handled by add_bootloader_randomness().
Jason
Quoted 5 lines · Jason A. Donenfeld
Hi Philippe,
Quoted 2 lines · Philippe Mathieu-Daudé
Quoted 1 line
+
add_bootloader_randomness(rng_seed, len);
Quoted 7 lines
Quoted 2 lines
So we call char/random code with len=0. Is it safe? Maybe simply safer to check len before calling hex2bin?
add_bootloader_randomness()is safe for all input sizes, and is written to be callable with len=0 and have no effect. So this function should be good as-is; there's no need to special case an unlikely instance that's already handled byadd_bootloader_randomness().
OK, thanks for the clarification.
Phil.