3a2c0ba5ad
current_rng holds one reference, and we bump it every time we want to do a read from it. This means we only hold the rng_mutex to grab or drop a reference, so accessing /sys/devices/virtual/misc/hw_random/rng_current doesn't block on read of /dev/hwrng. Using a kref is overkill (we're always under the rng_mutex), but a standard pattern. This also solves the problem that the hwrng_fillfn thread was accessing current_rng without a lock, which could change (eg. to NULL) underneath it. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Amos Kong <akong@redhat.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
/*
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Hardware Random Number Generator
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Please read Documentation/hw_random.txt for details on use.
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----------------------------------------------------------
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This software may be used and distributed according to the terms
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of the GNU General Public License, incorporated herein by reference.
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*/
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#ifndef LINUX_HWRANDOM_H_
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#define LINUX_HWRANDOM_H_
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/kref.h>
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/**
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* struct hwrng - Hardware Random Number Generator driver
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* @name: Unique RNG name.
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* @init: Initialization callback (can be NULL).
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* @cleanup: Cleanup callback (can be NULL).
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* @data_present: Callback to determine if data is available
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* on the RNG. If NULL, it is assumed that
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* there is always data available. *OBSOLETE*
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* @data_read: Read data from the RNG device.
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* Returns the number of lower random bytes in "data".
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* Must not be NULL. *OBSOLETE*
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* @read: New API. drivers can fill up to max bytes of data
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* into the buffer. The buffer is aligned for any type.
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* @priv: Private data, for use by the RNG driver.
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* @quality: Estimation of true entropy in RNG's bitstream
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* (per mill).
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*/
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struct hwrng {
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const char *name;
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int (*init)(struct hwrng *rng);
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void (*cleanup)(struct hwrng *rng);
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int (*data_present)(struct hwrng *rng, int wait);
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int (*data_read)(struct hwrng *rng, u32 *data);
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int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
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unsigned long priv;
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unsigned short quality;
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/* internal. */
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struct list_head list;
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struct kref ref;
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};
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/** Register a new Hardware Random Number Generator driver. */
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extern int hwrng_register(struct hwrng *rng);
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/** Unregister a Hardware Random Number Generator driver. */
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extern void hwrng_unregister(struct hwrng *rng);
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/** Feed random bits into the pool. */
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extern void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy);
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#endif /* LINUX_HWRANDOM_H_ */
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