ubusd_id: use GRND_INSECURE to avoid blocking boot on getrandom()#24
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Commit 4ca0b14 ("ubusd_id: use getrandom(2) unconditionally on Linux") switched ID allocation from non-blocking /dev/urandom reads to getrandom(buf, len, 0). With flags == 0, getrandom() blocks until the kernel CRNG is fully seeded. ubusd's first ID allocation runs inside procd's "ubus" stage, and procd does not advance past that stage until ubusd is up. urngd, which seeds the entropy pool quickly, is only started by procd after the "ubus" stage. On boards whose CRNG seeds slowly (e.g. Rockchip RK3328: NanoPi R2S / R2S Plus / R4S, Orange Pi R1 Plus LTS) nothing seeds the pool while ubusd waits, so boot stalls for minutes until slow timer/interrupt entropy fills it. ubus IDs only need to be hard to guess, not cryptographically strong, and were sourced from non-blocking /dev/urandom for years. Use GRND_INSECURE, which returns bytes immediately without waiting for the CRNG, restoring the previous early-boot behaviour while keeping the benefits of getrandom() (no file descriptor, works before /dev/urandom exists). Define GRND_INSECURE for libc headers predating Linux 5.6. Fixes: openwrt#21 Assisted-by: Claude:claude-opus-4-8 Link: openwrt#24 Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
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Commit 4ca0b14 ("ubusd_id: use getrandom(2) unconditionally on Linux") switched ID allocation from non-blocking /dev/urandom reads to getrandom(buf, len, 0). With flags == 0, getrandom() blocks until the kernel CRNG is fully seeded.
ubusd's first ID allocation runs inside procd's "ubus" stage, and procd does not advance past that stage until ubusd is up. urngd, which seeds the entropy pool quickly, is only started by procd after the "ubus" stage. On boards whose CRNG seeds slowly (e.g. Rockchip RK3328: NanoPi R2S / R2S Plus / R4S, Orange Pi R1 Plus LTS) nothing seeds the pool while ubusd waits, so boot stalls for minutes until slow timer/interrupt entropy fills it.
ubus IDs only need to be hard to guess, not cryptographically strong, and were sourced from non-blocking /dev/urandom for years. Use GRND_INSECURE, which returns bytes immediately without waiting for the CRNG, restoring the previous early-boot behaviour while keeping the benefits of getrandom() (no file descriptor, works before /dev/urandom exists). Define GRND_INSECURE for libc headers predating Linux 5.6.
Fixes: #21
Assisted-by: Claude:claude-opus-4-8