• Willy Tarreau's avatar
    random32: update the net random state on interrupt and activity · f227e3ec
    Willy Tarreau authored
    This modifies the first 32 bits out of the 128 bits of a random CPU's
    net_rand_state on interrupt or CPU activity to complicate remote
    observations that could lead to guessing the network RNG's internal
    state.
    
    Note that depending on some network devices' interrupt rate moderation
    or binding, this re-seeding might happen on every packet or even almost
    never.
    
    In addition, with NOHZ some CPUs might not even get timer interrupts,
    leaving their local state rarely updated, while they are running
    networked processes making use of the random state.  For this reason, we
    also perform this update in update_process_times() in order to at least
    update the state when there is user or system activity, since it's the
    only case we care about.
    Reported-by: default avatarAmit Klein <aksecurity@gmail.com>
    Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Cc: Eric Dumazet <edumazet@google.com>
    Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarWilly Tarreau <w@1wt.eu>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    f227e3ec
random.h 5.79 KB