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| author | Kees Cook <keescook@chromium.org> | 2019-04-19 23:27:05 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2019-04-19 23:27:05 -0400 |
| commit | d55535232c3dbde9a523a9d10d68670f5fe5dec3 (patch) | |
| tree | 43265cdcfde71ed2fdbd562c17f034c28aab15bc /init | |
| parent | eb9d1bf079bb438d1a066d72337092935fc770f6 (diff) | |
| download | lwn-d55535232c3dbde9a523a9d10d68670f5fe5dec3.tar.gz lwn-d55535232c3dbde9a523a9d10d68670f5fe5dec3.zip | |
random: move rand_initialize() earlier
Right now rand_initialize() is run as an early_initcall(), but it only
depends on timekeeping_init() (for mixing ktime_get_real() into the
pools). However, the call to boot_init_stack_canary() for stack canary
initialization runs earlier, which triggers a warning at boot:
random: get_random_bytes called from start_kernel+0x357/0x548 with crng_init=0
Instead, this moves rand_initialize() to after timekeeping_init(), and moves
canary initialization here as well.
Note that this warning may still remain for machines that do not have
UEFI RNG support (which initializes the RNG pools during setup_arch()),
or for x86 machines without RDRAND (or booting without "random.trust=on"
or CONFIG_RANDOM_TRUST_CPU=y).
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'init')
| -rw-r--r-- | init/main.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/init/main.c b/init/main.c index 598e278b46f7..55243bc0a067 100644 --- a/init/main.c +++ b/init/main.c @@ -564,13 +564,6 @@ asmlinkage __visible void __init start_kernel(void) page_address_init(); pr_notice("%s", linux_banner); setup_arch(&command_line); - /* - * Set up the the initial canary and entropy after arch - * and after adding latent and command line entropy. - */ - add_latent_entropy(); - add_device_randomness(command_line, strlen(command_line)); - boot_init_stack_canary(); mm_init_cpumask(&init_mm); setup_command_line(command_line); setup_nr_cpu_ids(); @@ -655,6 +648,20 @@ asmlinkage __visible void __init start_kernel(void) hrtimers_init(); softirq_init(); timekeeping_init(); + + /* + * For best initial stack canary entropy, prepare it after: + * - setup_arch() for any UEFI RNG entropy and boot cmdline access + * - timekeeping_init() for ktime entropy used in rand_initialize() + * - rand_initialize() to get any arch-specific entropy like RDRAND + * - add_latent_entropy() to get any latent entropy + * - adding command line entropy + */ + rand_initialize(); + add_latent_entropy(); + add_device_randomness(command_line, strlen(command_line)); + boot_init_stack_canary(); + time_init(); printk_safe_init(); perf_event_init(); |