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f5b98461cb
Now that our crng uses chacha20, we can rely on its speedy characteristics for replacing MD5, while simultaneously achieving a higher security guarantee. Before the idea was to use these functions if you wanted random integers that aren't stupidly insecure but aren't necessarily secure either, a vague gray zone, that hopefully was "good enough" for its users. With chacha20, we can strengthen this claim, since either we're using an rdrand-like instruction, or we're using the same crng as /dev/urandom. And it's faster than what was before. We could have chosen to replace this with a SipHash-derived function, which might be slightly faster, but at the cost of having yet another RNG construction in the kernel. By moving to chacha20, we have a single RNG to analyze and verify, and we also already get good performance improvements on all platforms. Implementation-wise, rather than use a generic buffer for both get_random_int/long and memcpy based on the size needs, we use a specific buffer for 32-bit reads and for 64-bit reads. This way, we're guaranteed to always have aligned accesses on all platforms. While slightly more verbose in C, the assembly this generates is a lot simpler than otherwise. Finally, on 32-bit platforms where longs and ints are the same size, we simply alias get_random_int to get_random_long. Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Suggested-by: Theodore Ts'o <tytso@mit.edu> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> Cc: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
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| .. | ||
| agp | ||
| hw_random | ||
| ipmi | ||
| mwave | ||
| pcmcia | ||
| tpm | ||
| xilinx_hwicap | ||
| xillybus | ||
| apm-emulation.c | ||
| applicom.c | ||
| applicom.h | ||
| bfin-otp.c | ||
| bsr.c | ||
| ds1302.c | ||
| ds1620.c | ||
| dsp56k.c | ||
| dtlk.c | ||
| efirtc.c | ||
| generic_nvram.c | ||
| hangcheck-timer.c | ||
| hpet.c | ||
| Kconfig | ||
| lp.c | ||
| Makefile | ||
| mbcs.c | ||
| mbcs.h | ||
| mem.c | ||
| misc.c | ||
| mmtimer.c | ||
| mspec.c | ||
| nsc_gpio.c | ||
| nvram.c | ||
| nwbutton.c | ||
| nwbutton.h | ||
| nwflash.c | ||
| pc8736x_gpio.c | ||
| powernv-op-panel.c | ||
| ppdev.c | ||
| ps3flash.c | ||
| random.c | ||
| raw.c | ||
| rtc.c | ||
| scx200_gpio.c | ||
| snsc_event.c | ||
| snsc.c | ||
| snsc.h | ||
| sonypi.c | ||
| tb0219.c | ||
| tile-srom.c | ||
| tlclk.c | ||
| toshiba.c | ||
| ttyprintk.c | ||
| uv_mmtimer.c | ||
| virtio_console.c | ||