Messages in this thread | | | Date | Tue, 27 Sep 2022 07:21:26 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] sethostname: dump new hostname into RNG |
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On Tue, Sep 27, 2022 at 11:40:39AM +0200, Jason A. Donenfeld wrote: > On some small machines with little entropy, a quasi-unique hostname is > sometimes a relevant factor. I've seen, for example, 8 character > alpha-numeric serial numbers. In addition, the time at which the hostname > is set is usually a decent measurement of how long early boot took. So, > call add_device_randomness() on new hostnames, which feeds its arguments > to the RNG in addition to a fresh cycle counter. > > Low cost hooks like this never hurt and can only ever help, and since > this costs basically nothing for an operation that is never a fast path, > this is an overall easy win.
Seems reasonable!
Reviewed-by: Kees Cook <keescook@chromium.org>
> > Cc: Kees Cook <keescook@chromium.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Dominik Brodowski <linux@dominikbrodowski.net> > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> > --- > kernel/sys.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/sys.c b/kernel/sys.c > index b911fa6d81ab..7b7f973ea585 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -1366,6 +1366,7 @@ SYSCALL_DEFINE2(sethostname, char __user *, name, int, len) > if (!copy_from_user(tmp, name, len)) { > struct new_utsname *u; > > + add_device_randomness(tmp, len); > down_write(&uts_sem); > u = utsname(); > memcpy(u->nodename, tmp, len); > -- > 2.37.3 >
-- Kees Cook
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