diff options
| author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-09-27 11:35:16 +0200 |
|---|---|---|
| committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-09-29 21:37:27 +0200 |
| commit | 37608ba315a2b1b548aa5b1064e5559e029cb016 (patch) | |
| tree | 8b4b2cd0188f9753c1b35eb0bd1c185bb913237a /kernel/sys.c | |
| parent | random: use init_utsname() instead of utsname() (diff) | |
| download | linux-37608ba315a2b1b548aa5b1064e5559e029cb016.tar.xz linux-37608ba315a2b1b548aa5b1064e5559e029cb016.zip | |
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 <akpm@linux-foundation.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'kernel/sys.c')
| -rw-r--r-- | kernel/sys.c | 3 |
1 files changed, 3 insertions, 0 deletions
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 <linux/times.h> #include <linux/posix-timers.h> #include <linux/security.h> +#include <linux/random.h> #include <linux/suspend.h> #include <linux/tty.h> #include <linux/signal.h> @@ -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); |