random: add GRND_INSECURE to return best-effort non-cryptographic bytes
Signed-off-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/d5473b56cf1fa900ca4bd2b3fc1e5b8874399919.1577088521.git.luto@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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@ -2194,7 +2194,14 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
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{
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int ret;
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if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
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if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE))
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return -EINVAL;
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/*
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* Requesting insecure and blocking randomness at the same time makes
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* no sense.
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*/
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if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM))
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return -EINVAL;
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if (count > INT_MAX)
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@ -2203,7 +2210,7 @@ SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
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if (flags & GRND_RANDOM)
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return _random_read(flags & GRND_NONBLOCK, buf, count);
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if (!crng_ready()) {
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if (!(flags & GRND_INSECURE) && !crng_ready()) {
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if (flags & GRND_NONBLOCK)
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return -EAGAIN;
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ret = wait_for_random_bytes();
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@ -49,8 +49,10 @@ struct rand_pool_info {
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*
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* GRND_NONBLOCK Don't block and return EAGAIN instead
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* GRND_RANDOM Use the /dev/random pool instead of /dev/urandom
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* GRND_INSECURE Return non-cryptographic random bytes
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*/
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#define GRND_NONBLOCK 0x0001
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#define GRND_RANDOM 0x0002
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#define GRND_INSECURE 0x0004
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#endif /* _UAPI_LINUX_RANDOM_H */
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