8e8f250422
We switched from thread-local storage to a mutex-pool in 82639e6f53
because, for highly-threaded processes, the memory used by all the
states could be quite large. I had judged that a mutex-pool should be
fine, but had underestimated the PRNG requirements of some of our jobs.
This change makes rand.c support using either thread-locals or a
mutex-pool. Thread-locals are used if fork-unsafe buffering is enabled.
While not strictly related to fork-safety, we already have the
fork-unsafe control, and it's already set by jobs that care a lot about
PRNG performance, so fits quite nicely here.
Change-Id: Iaf1e0171c70d4c8dbe1e42283ea13df5b613cb2d
Reviewed-on: https://boringssl-review.googlesource.com/c/31564
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
130 lines
4.7 KiB
C
130 lines
4.7 KiB
C
/* Copyright (c) 2014, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#ifndef OPENSSL_HEADER_RAND_H
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#define OPENSSL_HEADER_RAND_H
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#include <openssl/base.h>
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#if defined(__cplusplus)
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extern "C" {
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#endif
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// Random number generation.
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// RAND_bytes writes |len| bytes of random data to |buf| and returns one.
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OPENSSL_EXPORT int RAND_bytes(uint8_t *buf, size_t len);
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// RAND_cleanup frees any resources used by the RNG. This is not safe if other
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// threads might still be calling |RAND_bytes|.
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OPENSSL_EXPORT void RAND_cleanup(void);
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// Obscure functions.
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#if !defined(OPENSSL_WINDOWS)
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// RAND_set_urandom_fd causes the module to use a copy of |fd| for system
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// randomness rather opening /dev/urandom internally. The caller retains
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// ownership of |fd| and is at liberty to close it at any time. This is useful
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// if, due to a sandbox, /dev/urandom isn't available. If used, it must be
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// called before the first call to |RAND_bytes|, and it is mutually exclusive
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// with |RAND_enable_fork_unsafe_buffering|.
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//
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// |RAND_set_urandom_fd| does not buffer any entropy, so it is safe to call
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// |fork| at any time after calling |RAND_set_urandom_fd|.
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OPENSSL_EXPORT void RAND_set_urandom_fd(int fd);
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// RAND_enable_fork_unsafe_buffering enables efficient buffered reading of
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// /dev/urandom. It adds an overhead of a few KB of memory per thread. It must
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// be called before the first call to |RAND_bytes| and it is mutually exclusive
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// with calls to |RAND_set_urandom_fd|.
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//
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// If |fd| is non-negative then a copy of |fd| will be used rather than opening
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// /dev/urandom internally. Like |RAND_set_urandom_fd|, the caller retains
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// ownership of |fd|. If |fd| is negative then /dev/urandom will be opened and
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// any error from open(2) crashes the address space.
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//
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// Setting this also enables thread-local PRNG state, which can reduce lock
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// contention in highly-threaded applications although at the cost of yet more
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// memory.
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//
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// It has an unusual name because the buffer is unsafe across calls to |fork|.
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// Hence, this function should never be called by libraries.
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OPENSSL_EXPORT void RAND_enable_fork_unsafe_buffering(int fd);
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#endif
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#if defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE)
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// RAND_reset_for_fuzzing resets the fuzzer-only deterministic RNG. This
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// function is only defined in the fuzzer-only build configuration.
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OPENSSL_EXPORT void RAND_reset_for_fuzzing(void);
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#endif
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// Deprecated functions
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// RAND_pseudo_bytes is a wrapper around |RAND_bytes|.
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OPENSSL_EXPORT int RAND_pseudo_bytes(uint8_t *buf, size_t len);
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// RAND_seed reads a single byte of random data to ensure that any file
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// descriptors etc are opened.
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OPENSSL_EXPORT void RAND_seed(const void *buf, int num);
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// RAND_load_file returns a nonnegative number.
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OPENSSL_EXPORT int RAND_load_file(const char *path, long num);
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// RAND_file_name returns NULL.
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OPENSSL_EXPORT const char *RAND_file_name(char *buf, size_t num);
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// RAND_add does nothing.
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OPENSSL_EXPORT void RAND_add(const void *buf, int num, double entropy);
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// RAND_egd returns 255.
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OPENSSL_EXPORT int RAND_egd(const char *);
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// RAND_poll returns one.
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OPENSSL_EXPORT int RAND_poll(void);
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// RAND_status returns one.
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OPENSSL_EXPORT int RAND_status(void);
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// rand_meth_st is typedefed to |RAND_METHOD| in base.h. It isn't used; it
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// exists only to be the return type of |RAND_SSLeay|. It's
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// external so that variables of this type can be initialized.
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struct rand_meth_st {
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void (*seed) (const void *buf, int num);
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int (*bytes) (uint8_t *buf, size_t num);
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void (*cleanup) (void);
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void (*add) (const void *buf, int num, double entropy);
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int (*pseudorand) (uint8_t *buf, size_t num);
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int (*status) (void);
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};
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// RAND_SSLeay returns a pointer to a dummy |RAND_METHOD|.
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OPENSSL_EXPORT RAND_METHOD *RAND_SSLeay(void);
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// RAND_get_rand_method returns |RAND_SSLeay()|.
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OPENSSL_EXPORT const RAND_METHOD *RAND_get_rand_method(void);
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// RAND_set_rand_method does nothing.
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OPENSSL_EXPORT void RAND_set_rand_method(const RAND_METHOD *);
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#if defined(__cplusplus)
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} // extern C
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#endif
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#endif // OPENSSL_HEADER_RAND_H
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