--- /dev/null
+/* Copyright (c) 2014, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/rand.h>
+
+#include <assert.h>
+#include <limits.h>
+#include <string.h>
+
+#if defined(BORINGSSL_FIPS)
+#include <unistd.h>
+#endif
+
+#include <openssl/chacha.h>
+#include <openssl/cpu.h>
+#include <openssl/mem.h>
+
+#include "internal.h"
+#include "../../internal.h"
+#include "../delocate.h"
+
+
+// It's assumed that the operating system always has an unfailing source of
+// entropy which is accessed via |CRYPTO_sysrand|. (If the operating system
+// entropy source fails, it's up to |CRYPTO_sysrand| to abort the process—we
+// don't try to handle it.)
+//
+// In addition, the hardware may provide a low-latency RNG. Intel's rdrand
+// instruction is the canonical example of this. When a hardware RNG is
+// available we don't need to worry about an RNG failure arising from fork()ing
+// the process or moving a VM, so we can keep thread-local RNG state and use it
+// as an additional-data input to CTR-DRBG.
+//
+// (We assume that the OS entropy is safe from fork()ing and VM duplication.
+// This might be a bit of a leap of faith, esp on Windows, but there's nothing
+// that we can do about it.)
+
+// kReseedInterval is the number of generate calls made to CTR-DRBG before
+// reseeding.
+static const unsigned kReseedInterval = 4096;
+
+// CRNGT_BLOCK_SIZE is the number of bytes in a “block” for the purposes of the
+// continuous random number generator test in FIPS 140-2, section 4.9.2.
+#define CRNGT_BLOCK_SIZE 16
+
+// rand_thread_state contains the per-thread state for the RNG.
+struct rand_thread_state {
+ CTR_DRBG_STATE drbg;
+ // calls is the number of generate calls made on |drbg| since it was last
+ // (re)seeded. This is bound by |kReseedInterval|.
+ unsigned calls;
+ // last_block_valid is non-zero iff |last_block| contains data from
+ // |CRYPTO_sysrand|.
+ int last_block_valid;
+
+#if defined(BORINGSSL_FIPS)
+ // last_block contains the previous block from |CRYPTO_sysrand|.
+ uint8_t last_block[CRNGT_BLOCK_SIZE];
+ // next and prev form a NULL-terminated, double-linked list of all states in
+ // a process.
+ struct rand_thread_state *next, *prev;
+#endif
+};
+
+#if defined(BORINGSSL_FIPS)
+// thread_states_list is the head of a linked-list of all |rand_thread_state|
+// objects in the process, one per thread. This is needed because FIPS requires
+// that they be zeroed on process exit, but thread-local destructors aren't
+// called when the whole process is exiting.
+DEFINE_BSS_GET(struct rand_thread_state *, thread_states_list);
+DEFINE_STATIC_MUTEX(thread_states_list_lock);
+
+static void rand_thread_state_clear_all(void) __attribute__((destructor));
+static void rand_thread_state_clear_all(void) {
+ CRYPTO_STATIC_MUTEX_lock_write(thread_states_list_lock_bss_get());
+ for (struct rand_thread_state *cur = *thread_states_list_bss_get();
+ cur != NULL; cur = cur->next) {
+ CTR_DRBG_clear(&cur->drbg);
+ }
+ // |thread_states_list_lock is deliberately left locked so that any threads
+ // that are still running will hang if they try to call |RAND_bytes|.
+}
+#endif
+
+// rand_thread_state_free frees a |rand_thread_state|. This is called when a
+// thread exits.
+static void rand_thread_state_free(void *state_in) {
+ struct rand_thread_state *state = state_in;
+
+ if (state_in == NULL) {
+ return;
+ }
+
+#if defined(BORINGSSL_FIPS)
+ CRYPTO_STATIC_MUTEX_lock_write(thread_states_list_lock_bss_get());
+
+ if (state->prev != NULL) {
+ state->prev->next = state->next;
+ } else {
+ *thread_states_list_bss_get() = state->next;
+ }
+
+ if (state->next != NULL) {
+ state->next->prev = state->prev;
+ }
+
+ CRYPTO_STATIC_MUTEX_unlock_write(thread_states_list_lock_bss_get());
+
+ CTR_DRBG_clear(&state->drbg);
+#endif
+
+ OPENSSL_free(state);
+}
+
+#if defined(OPENSSL_X86_64) && !defined(OPENSSL_NO_ASM) && \
+ !defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE)
+
+// These functions are defined in asm/rdrand-x86_64.pl
+extern int CRYPTO_rdrand(uint8_t out[8]);
+extern int CRYPTO_rdrand_multiple8_buf(uint8_t *buf, size_t len);
+
+static int have_rdrand(void) {
+ return (OPENSSL_ia32cap_get()[1] & (1u << 30)) != 0;
+}
+
+static int hwrand(uint8_t *buf, const size_t len) {
+ if (!have_rdrand()) {
+ return 0;
+ }
+
+ const size_t len_multiple8 = len & ~7;
+ if (!CRYPTO_rdrand_multiple8_buf(buf, len_multiple8)) {
+ return 0;
+ }
+ const size_t remainder = len - len_multiple8;
+
+ if (remainder != 0) {
+ assert(remainder < 8);
+
+ uint8_t rand_buf[8];
+ if (!CRYPTO_rdrand(rand_buf)) {
+ return 0;
+ }
+ OPENSSL_memcpy(buf + len_multiple8, rand_buf, remainder);
+ }
+
+#if defined(BORINGSSL_FIPS_BREAK_CRNG)
+ // This breaks the "continuous random number generator test" defined in FIPS
+ // 140-2, section 4.9.2, and implemented in rand_get_seed().
+ OPENSSL_memset(buf, 0, len);
+#endif
+
+ return 1;
+}
+
+#else
+
+static int hwrand(uint8_t *buf, size_t len) {
+ return 0;
+}
+
+#endif
+
+#if defined(BORINGSSL_FIPS)
+
+static void rand_get_seed(struct rand_thread_state *state,
+ uint8_t seed[CTR_DRBG_ENTROPY_LEN]) {
+ if (!state->last_block_valid) {
+ if (!hwrand(state->last_block, sizeof(state->last_block))) {
+ CRYPTO_sysrand(state->last_block, sizeof(state->last_block));
+ }
+ state->last_block_valid = 1;
+ }
+
+ // We overread from /dev/urandom or RDRAND by a factor of 10 and XOR to
+ // whiten.
+#define FIPS_OVERREAD 10
+ uint8_t entropy[CTR_DRBG_ENTROPY_LEN * FIPS_OVERREAD];
+
+ if (!hwrand(entropy, sizeof(entropy))) {
+ CRYPTO_sysrand(entropy, sizeof(entropy));
+ }
+
+ // See FIPS 140-2, section 4.9.2. This is the “continuous random number
+ // generator test” which causes the program to randomly abort. Hopefully the
+ // rate of failure is small enough not to be a problem in practice.
+ if (CRYPTO_memcmp(state->last_block, entropy, CRNGT_BLOCK_SIZE) == 0) {
+ printf("CRNGT failed.\n");
+ BORINGSSL_FIPS_abort();
+ }
+
+ for (size_t i = CRNGT_BLOCK_SIZE; i < sizeof(entropy);
+ i += CRNGT_BLOCK_SIZE) {
+ if (CRYPTO_memcmp(entropy + i - CRNGT_BLOCK_SIZE, entropy + i,
+ CRNGT_BLOCK_SIZE) == 0) {
+ printf("CRNGT failed.\n");
+ BORINGSSL_FIPS_abort();
+ }
+ }
+ OPENSSL_memcpy(state->last_block,
+ entropy + sizeof(entropy) - CRNGT_BLOCK_SIZE,
+ CRNGT_BLOCK_SIZE);
+
+ OPENSSL_memcpy(seed, entropy, CTR_DRBG_ENTROPY_LEN);
+
+ for (size_t i = 1; i < FIPS_OVERREAD; i++) {
+ for (size_t j = 0; j < CTR_DRBG_ENTROPY_LEN; j++) {
+ seed[j] ^= entropy[CTR_DRBG_ENTROPY_LEN * i + j];
+ }
+ }
+}
+
+#else
+
+static void rand_get_seed(struct rand_thread_state *state,
+ uint8_t seed[CTR_DRBG_ENTROPY_LEN]) {
+ // If not in FIPS mode, we don't overread from the system entropy source and
+ // we don't depend only on the hardware RDRAND.
+ CRYPTO_sysrand(seed, CTR_DRBG_ENTROPY_LEN);
+}
+
+#endif
+
+void RAND_bytes_with_additional_data(uint8_t *out, size_t out_len,
+ const uint8_t user_additional_data[32]) {
+ if (out_len == 0) {
+ return;
+ }
+
+ // Additional data is mixed into every CTR-DRBG call to protect, as best we
+ // can, against forks & VM clones. We do not over-read this information and
+ // don't reseed with it so, from the point of view of FIPS, this doesn't
+ // provide “prediction resistance”. But, in practice, it does.
+ uint8_t additional_data[32];
+ if (!hwrand(additional_data, sizeof(additional_data))) {
+ // Without a hardware RNG to save us from address-space duplication, the OS
+ // entropy is used. This can be expensive (one read per |RAND_bytes| call)
+ // and so can be disabled by applications that we have ensured don't fork
+ // and aren't at risk of VM cloning.
+ if (!rand_fork_unsafe_buffering_enabled()) {
+ CRYPTO_sysrand(additional_data, sizeof(additional_data));
+ } else {
+ OPENSSL_memset(additional_data, 0, sizeof(additional_data));
+ }
+ }
+
+ for (size_t i = 0; i < sizeof(additional_data); i++) {
+ additional_data[i] ^= user_additional_data[i];
+ }
+
+ struct rand_thread_state stack_state;
+ struct rand_thread_state *state =
+ CRYPTO_get_thread_local(OPENSSL_THREAD_LOCAL_RAND);
+
+ if (state == NULL) {
+ state = OPENSSL_malloc(sizeof(struct rand_thread_state));
+ if (state == NULL ||
+ !CRYPTO_set_thread_local(OPENSSL_THREAD_LOCAL_RAND, state,
+ rand_thread_state_free)) {
+ // If the system is out of memory, use an ephemeral state on the
+ // stack.
+ state = &stack_state;
+ }
+
+ state->last_block_valid = 0;
+ uint8_t seed[CTR_DRBG_ENTROPY_LEN];
+ rand_get_seed(state, seed);
+ if (!CTR_DRBG_init(&state->drbg, seed, NULL, 0)) {
+ abort();
+ }
+ state->calls = 0;
+
+#if defined(BORINGSSL_FIPS)
+ if (state != &stack_state) {
+ CRYPTO_STATIC_MUTEX_lock_write(thread_states_list_lock_bss_get());
+ struct rand_thread_state **states_list = thread_states_list_bss_get();
+ state->next = *states_list;
+ if (state->next != NULL) {
+ state->next->prev = state;
+ }
+ state->prev = NULL;
+ *states_list = state;
+ CRYPTO_STATIC_MUTEX_unlock_write(thread_states_list_lock_bss_get());
+ }
+#endif
+ }
+
+ if (state->calls >= kReseedInterval) {
+ uint8_t seed[CTR_DRBG_ENTROPY_LEN];
+ rand_get_seed(state, seed);
+#if defined(BORINGSSL_FIPS)
+ // Take a read lock around accesses to |state->drbg|. This is needed to
+ // avoid returning bad entropy if we race with
+ // |rand_thread_state_clear_all|.
+ //
+ // This lock must be taken after any calls to |CRYPTO_sysrand| to avoid a
+ // bug on ppc64le. glibc may implement pthread locks by wrapping user code
+ // in a hardware transaction, but, on some older versions of glibc and the
+ // kernel, syscalls made with |syscall| did not abort the transaction.
+ CRYPTO_STATIC_MUTEX_lock_read(thread_states_list_lock_bss_get());
+#endif
+ if (!CTR_DRBG_reseed(&state->drbg, seed, NULL, 0)) {
+ abort();
+ }
+ state->calls = 0;
+ } else {
+#if defined(BORINGSSL_FIPS)
+ CRYPTO_STATIC_MUTEX_lock_read(thread_states_list_lock_bss_get());
+#endif
+ }
+
+ int first_call = 1;
+ while (out_len > 0) {
+ size_t todo = out_len;
+ if (todo > CTR_DRBG_MAX_GENERATE_LENGTH) {
+ todo = CTR_DRBG_MAX_GENERATE_LENGTH;
+ }
+
+ if (!CTR_DRBG_generate(&state->drbg, out, todo, additional_data,
+ first_call ? sizeof(additional_data) : 0)) {
+ abort();
+ }
+
+ out += todo;
+ out_len -= todo;
+ state->calls++;
+ first_call = 0;
+ }
+
+ if (state == &stack_state) {
+ CTR_DRBG_clear(&state->drbg);
+ }
+
+#if defined(BORINGSSL_FIPS)
+ CRYPTO_STATIC_MUTEX_unlock_read(thread_states_list_lock_bss_get());
+#endif
+}
+
+int RAND_bytes(uint8_t *out, size_t out_len) {
+ static const uint8_t kZeroAdditionalData[32] = {0};
+ RAND_bytes_with_additional_data(out, out_len, kZeroAdditionalData);
+ return 1;
+}
+
+int RAND_pseudo_bytes(uint8_t *buf, size_t len) {
+ return RAND_bytes(buf, len);
+}
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