From 37608ba315a2b1b548aa5b1064e5559e029cb016 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 27 Sep 2022 11:35:16 +0200 Subject: utsname: contribute changes to RNG 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. Cc: Andrew Morton Cc: Dominik Brodowski Reviewed-by: Kees Cook Signed-off-by: Jason A. Donenfeld --- kernel/sys.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/sys.c') diff --git a/kernel/sys.c b/kernel/sys.c index b911fa6d81ab..35339bd5fc9f 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -1366,6 +1367,7 @@ 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); @@ -1419,6 +1421,7 @@ SYSCALL_DEFINE2(setdomainname, 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->domainname, tmp, len); -- cgit