3946a55291
This commit:
1) seed /dev/urandom with the saved seeds as early as possible
(see /lib/preinit/81_urandom_seed)
2) save a seed at /etc/urandom.seed if it doesn't exists
3) save a new seed each boot at "system.@system[0].urandom_seed"
(see /etc/init.d/urandom_seed)
We use getrandom() so we are sure /dev/urandom pool is initialized
Seed size is 512 bytes (ie /proc/sys/kernel/random/poolsize / 8)
it's the same size as in ubuntu 14.04 and all systemd systems
Seeding /dev/urandom doesn't change entropy estimation, so we still have
"random: ubus urandom read with 4 bits of entropy available"
messages in the logs, but we can now ignore them if
after "urandom-seed: Seeding with ..." message
Saving a new seed on each boot is disabled by default to avoid too much
writes without user consent
v2: log preinit messages to /dev/kmsg
v3: use non generic function name for logging, as /lib/preinit/ files
are all sourced together in /etc/preinit
v4: after a lot of discussion on the ML, use a uci config param
v5: config param is now the path of the seed
Signed-off-by: Etienne CHAMPETIER <champetier.etienne@gmail.com>
Acked-by: Jo-Philipp Wich <jo@mein.io>
24 lines
703 B
Bash
24 lines
703 B
Bash
#!/bin/sh
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log_urandom_seed() {
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echo "urandom-seed: $1" > /dev/kmsg
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}
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_do_urandom_seed() {
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[ -f "$1" ] || { log_urandom_seed "Seed file not found ($1)"; return; }
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[ -O "$1" -a -G "$1" -a ! -x "$1" ] || { log_urandom_seed "Wrong owner / permissions for $1"; return; }
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log_urandom_seed "Seeding with $1"
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cat "$1" > /dev/urandom
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}
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do_urandom_seed() {
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[ -c /dev/urandom ] || { log_urandom_seed "Something is wrong with /dev/urandom"; return; }
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_do_urandom_seed "/etc/urandom.seed"
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SEED="$(uci -q get system.@system[0].urandom_seed)"
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[ "${SEED:0:1}" == "/" -a "$SEED" != "/etc/urandom.seed" ] && _do_urandom_seed "$SEED"
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}
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boot_hook_add preinit_main do_urandom_seed
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