WIP - entropy
diff --git a/src/arch/arm/include/bits/entropy.h b/src/arch/arm/include/bits/entropy.h
deleted file mode 100644
index 75fdc90..0000000
--- a/src/arch/arm/include/bits/entropy.h
+++ /dev/null
@@ -1,12 +0,0 @@
-#ifndef _BITS_ENTROPY_H
-#define _BITS_ENTROPY_H
-
-/** @file
- *
- * ARM-specific entropy API implementations
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#endif /* _BITS_ENTROPY_H */
diff --git a/src/arch/loong64/include/bits/entropy.h b/src/arch/loong64/include/bits/entropy.h
deleted file mode 100644
index 8d37269..0000000
--- a/src/arch/loong64/include/bits/entropy.h
+++ /dev/null
@@ -1,12 +0,0 @@
-#ifndef _BITS_ENTROPY_H
-#define _BITS_ENTROPY_H
-
-/** @file
- *
- * LoongArch64-specific entropy API implementations
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#endif /* _BITS_ENTROPY_H */
diff --git a/src/arch/x86/core/rdrand.c b/src/arch/x86/core/rdrand.c
index 29605ab..850ab1f 100644
--- a/src/arch/x86/core/rdrand.c
+++ b/src/arch/x86/core/rdrand.c
@@ -32,12 +32,15 @@
#include <errno.h>
#include <ipxe/cpuid.h>
#include <ipxe/entropy.h>
+#include <ipxe/drbg.h>
+
+struct entropy_source rdrand_entropy __entropy_source ( ENTROPY_PREFERRED );
/** Number of times to retry RDRAND instruction */
#define RDRAND_RETRY_COUNT 16
/** Colour for debug messages */
-#define colour CPUID_FEATURES_INTEL_ECX_RDRAND
+#define colour &rdrand_entropy
/**
* Enable entropy gathering
@@ -54,19 +57,18 @@
return -ENOTSUP;
}
+ /* Data returned by RDRAND is theoretically full entropy, up
+ * to a security strength of 128 bits, so assume that each
+ * sample contains exactly 8 bits of entropy.
+ */
+ if ( DRBG_SECURITY_STRENGTH > 128 )
+ return -ENOTSUP;
+ entropy_init ( &rdrand_entropy, MIN_ENTROPY ( 8.0 ) );
+
return 0;
}
/**
- * Disable entropy gathering
- *
- */
-static void rdrand_entropy_disable ( void ) {
-
- /* Nothing to do */
-}
-
-/**
* Get noise sample
*
* @ret noise Noise sample
@@ -93,7 +95,9 @@
return 0;
}
-PROVIDE_ENTROPY_INLINE ( rdrand, min_entropy_per_sample );
-PROVIDE_ENTROPY ( rdrand, entropy_enable, rdrand_entropy_enable );
-PROVIDE_ENTROPY ( rdrand, entropy_disable, rdrand_entropy_disable );
-PROVIDE_ENTROPY ( rdrand, get_noise, rdrand_get_noise );
+/** Hardware random number generator entropy source */
+struct entropy_source rdrand_entropy __entropy_source ( ENTROPY_PREFERRED ) = {
+ .name = "rdrand",
+ .enable = rdrand_entropy_enable,
+ .get_noise = rdrand_get_noise,
+};
diff --git a/src/arch/x86/include/bits/entropy.h b/src/arch/x86/include/bits/entropy.h
deleted file mode 100644
index 7accea3..0000000
--- a/src/arch/x86/include/bits/entropy.h
+++ /dev/null
@@ -1,15 +0,0 @@
-#ifndef _BITS_ENTROPY_H
-#define _BITS_ENTROPY_H
-
-/** @file
- *
- * x86-specific entropy API implementations
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#include <ipxe/rtc_entropy.h>
-#include <ipxe/rdrand.h>
-
-#endif /* _BITS_ENTROPY_H */
diff --git a/src/arch/x86/include/ipxe/rdrand.h b/src/arch/x86/include/ipxe/rdrand.h
deleted file mode 100644
index c9c170f..0000000
--- a/src/arch/x86/include/ipxe/rdrand.h
+++ /dev/null
@@ -1,37 +0,0 @@
-#ifndef _IPXE_RDRAND_H
-#define _IPXE_RDRAND_H
-
-/** @file
- *
- * Hardware random number generator
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#include <stdint.h>
-#include <ipxe/drbg.h>
-
-#ifdef ENTROPY_RDRAND
-#define ENTROPY_PREFIX_rdrand
-#else
-#define ENTROPY_PREFIX_rdrand __rdrand_
-#endif
-
-/**
- * min-entropy per sample
- *
- * @ret min_entropy min-entropy of each sample
- */
-static inline __always_inline min_entropy_t
-ENTROPY_INLINE ( rdrand, min_entropy_per_sample ) ( void ) {
-
- /* Data returned by RDRAND is theoretically full entropy, up
- * to a security strength of 128 bits.
- */
- if ( DRBG_SECURITY_STRENGTH > 128 )
- return 0;
- return MIN_ENTROPY ( 8 * sizeof ( noise_sample_t ) );
-}
-
-#endif /* _IPXE_RDRAND_H */
diff --git a/src/arch/x86/include/ipxe/rtc_entropy.h b/src/arch/x86/include/ipxe/rtc_entropy.h
deleted file mode 100644
index 581abcd..0000000
--- a/src/arch/x86/include/ipxe/rtc_entropy.h
+++ /dev/null
@@ -1,62 +0,0 @@
-#ifndef _IPXE_RTC_ENTROPY_H
-#define _IPXE_RTC_ENTROPY_H
-
-/** @file
- *
- * RTC-based entropy source
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#include <stdint.h>
-
-#ifdef ENTROPY_RTC
-#define ENTROPY_PREFIX_rtc
-#else
-#define ENTROPY_PREFIX_rtc __rtc_
-#endif
-
-/**
- * min-entropy per sample
- *
- * @ret min_entropy min-entropy of each sample
- */
-static inline __always_inline min_entropy_t
-ENTROPY_INLINE ( rtc, min_entropy_per_sample ) ( void ) {
-
- /* The min-entropy has been measured on several platforms
- * using the entropy_sample test code. Modelling the samples
- * as independent, and using a confidence level of 99.99%, the
- * measurements were as follows:
- *
- * qemu-kvm : 7.38 bits
- * VMware : 7.46 bits
- * Physical hardware : 2.67 bits
- *
- * We choose the lowest of these (2.67 bits) and apply a 50%
- * safety margin to allow for some potential non-independence
- * of samples.
- */
- return MIN_ENTROPY ( 1.3 );
-}
-
-extern uint8_t rtc_sample ( void );
-
-/**
- * Get noise sample
- *
- * @ret noise Noise sample
- * @ret rc Return status code
- */
-static inline __always_inline int
-ENTROPY_INLINE ( rtc, get_noise ) ( noise_sample_t *noise ) {
-
- /* Get sample */
- *noise = rtc_sample();
-
- /* Always successful */
- return 0;
-}
-
-#endif /* _IPXE_RTC_ENTROPY_H */
diff --git a/src/arch/x86/interface/pcbios/rtc_entropy.c b/src/arch/x86/interface/pcbios/rtc_entropy.c
index c400d8a..8f47ff6 100644
--- a/src/arch/x86/interface/pcbios/rtc_entropy.c
+++ b/src/arch/x86/interface/pcbios/rtc_entropy.c
@@ -39,6 +39,8 @@
#include <ipxe/cpuid.h>
#include <ipxe/entropy.h>
+struct entropy_source rtc_entropy __entropy_source ( ENTROPY_NORMAL );
+
/** Maximum time to wait for an RTC interrupt, in milliseconds */
#define RTC_MAX_WAIT_MS 100
@@ -203,6 +205,21 @@
if ( ( rc = rtc_entropy_check() ) != 0 )
goto err_check;
+ /* The min-entropy has been measured on several platforms
+ * using the entropy_sample test code. Modelling the samples
+ * as independent, and using a confidence level of 99.99%, the
+ * measurements were as follows:
+ *
+ * qemu-kvm : 7.38 bits
+ * VMware : 7.46 bits
+ * Physical hardware : 2.67 bits
+ *
+ * We choose the lowest of these (2.67 bits) and apply a 50%
+ * safety margin to allow for some potential non-independence
+ * of samples.
+ */
+ entropy_init ( &rtc_entropy, MIN_ENTROPY ( 1.3 ) );
+
return 0;
err_check:
@@ -226,11 +243,12 @@
}
/**
- * Measure a single RTC tick
+ * Get noise sample
*
- * @ret delta Length of RTC tick (in TSC units)
+ * @ret noise Noise sample
+ * @ret rc Return status code
*/
-uint8_t rtc_sample ( void ) {
+static int rtc_get_noise ( noise_sample_t *noise ) {
uint32_t before;
uint32_t after;
uint32_t temp;
@@ -265,10 +283,14 @@
: "=a" ( after ), "=d" ( before ), "=Q" ( temp )
: "2" ( 0 ) );
- return ( after - before );
+ *noise = ( after - before );
+ return 0;
}
-PROVIDE_ENTROPY_INLINE ( rtc, min_entropy_per_sample );
-PROVIDE_ENTROPY ( rtc, entropy_enable, rtc_entropy_enable );
-PROVIDE_ENTROPY ( rtc, entropy_disable, rtc_entropy_disable );
-PROVIDE_ENTROPY_INLINE ( rtc, get_noise );
+/** RTC entropy source */
+struct entropy_source rtc_entropy __entropy_source ( ENTROPY_NORMAL ) = {
+ .name = "rtc",
+ .enable = rtc_entropy_enable,
+ .disable = rtc_entropy_disable,
+ .get_noise = rtc_get_noise,
+};
diff --git a/src/crypto/entropy.c b/src/crypto/entropy.c
index ced6fd9..6490c8e 100644
--- a/src/crypto/entropy.c
+++ b/src/crypto/entropy.c
@@ -50,46 +50,61 @@
#define EINFO_EPIPE_ADAPTIVE_PROPORTION_TEST \
__einfo_uniqify ( EINFO_EPIPE, 0x02, "Adaptive proportion test failed" )
+/** Current entropy source */
+static struct entropy_source *entropy_source;
+
/**
- * Calculate cutoff value for the repetition count test
+ * Enable entropy gathering
*
- * @ret cutoff Cutoff value
- *
- * This is the cutoff value for the Repetition Count Test defined in
- * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.2.
+ * @ret rc Return status code
*/
-static inline __attribute__ (( always_inline )) unsigned int
-repetition_count_cutoff ( void ) {
- double max_repetitions;
- unsigned int cutoff;
+int entropy_enable ( void ) {
+ int rc;
- /* The cutoff formula for the repetition test is:
- *
- * C = ( 1 + ( -log2(W) / H_min ) )
- *
- * where W is set at 2^(-30) (in ANS X9.82 Part 2 (October
- * 2011 Draft) Section 8.5.2.1.3.1).
- */
- max_repetitions = ( 1 + ( MIN_ENTROPY ( 30 ) /
- min_entropy_per_sample() ) );
+ /* Enable selected source, if applicable */
+ if ( entropy_source ) {
- /* Round up to a whole number of repetitions. We don't have
- * the ceil() function available, so do the rounding by hand.
- */
- cutoff = max_repetitions;
- if ( cutoff < max_repetitions )
- cutoff++;
- linker_assert ( ( cutoff >= max_repetitions ), rounding_error );
+ /* Enable entropy source */
+ if ( ( rc = entropy_source->enable() ) != 0 ) {
+ DBGC ( &entropy_source, "ENTROPY could not enable "
+ "source %s: %s\n", entropy_source->name,
+ strerror ( rc ) );
+ return rc;
+ }
- /* Floating-point operations are not allowed in iPXE since we
- * never set up a suitable environment. Abort the build
- * unless the calculated number of repetitions is a
- * compile-time constant.
- */
- linker_assert ( __builtin_constant_p ( cutoff ),
- repetition_count_cutoff_not_constant );
+ /* Sanity checks */
+ assert ( entropy_source->min_entropy_per_sample > 0 );
+ assert ( entropy_source->repetition_count_cutoff > 0 );
+ assert ( entropy_source->adaptive_proportion_cutoff > 0 );
+ assert ( entropy_source->startup_test_count > 0 );
- return cutoff;
+ return 0;
+ }
+
+ /* Find the first working source */
+ rc = -ENOENT;
+ for_each_table_entry ( entropy_source, ENTROPY_SOURCES ) {
+ if ( ( rc = entropy_enable() ) == 0 ) {
+ DBGC ( &entropy_source, "ENTROPY using source %s\n",
+ entropy_source->name );
+ break;
+ }
+ }
+ return rc;
+}
+
+/**
+ * Disable entropy gathering
+ *
+ */
+void entropy_disable ( void ) {
+
+ /* Sanity check */
+ assert ( entropy_source != NULL );
+
+ /* Disable entropy gathering, if applicable */
+ if ( entropy_source->disable )
+ entropy_source->disable();
}
/**
@@ -104,6 +119,8 @@
static int repetition_count_test ( noise_sample_t sample ) {
static noise_sample_t most_recent_sample;
static unsigned int repetition_count = 0;
+ unsigned int repetition_count_cutoff =
+ entropy_source->repetition_count_cutoff;
/* A = the most recently seen sample value
* B = the number of times that value A has been seen in a row
@@ -124,7 +141,7 @@
/* i. If B >= C, then an error condition is raised
* due to a failure of the test
*/
- if ( repetition_count >= repetition_count_cutoff() )
+ if ( repetition_count >= repetition_count_cutoff )
return -EPIPE_REPETITION_COUNT_TEST;
} else {
@@ -142,117 +159,6 @@
}
/**
- * Window size for the adaptive proportion test
- *
- * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.3.1.1 allows
- * five possible window sizes: 16, 64, 256, 4096 and 65536.
- *
- * We expect to generate relatively few (<256) entropy samples during
- * a typical iPXE run; the use of a large window size would mean that
- * the test would never complete a single cycle. We use a window size
- * of 64, which is the smallest window size that permits values of
- * H_min down to one bit per sample.
- */
-#define ADAPTIVE_PROPORTION_WINDOW_SIZE 64
-
-/**
- * Combine adaptive proportion test window size and min-entropy
- *
- * @v n N (window size)
- * @v h H (min-entropy)
- * @ret n_h (N,H) combined value
- */
-#define APC_N_H( n, h ) ( ( (n) << 8 ) | (h) )
-
-/**
- * Define a row of the adaptive proportion cutoff table
- *
- * @v h H (min-entropy)
- * @v c16 Cutoff for N=16
- * @v c64 Cutoff for N=64
- * @v c256 Cutoff for N=256
- * @v c4096 Cutoff for N=4096
- * @v c65536 Cutoff for N=65536
- */
-#define APC_TABLE_ROW( h, c16, c64, c256, c4096, c65536) \
- case APC_N_H ( 16, h ) : return c16; \
- case APC_N_H ( 64, h ) : return c64; \
- case APC_N_H ( 256, h ) : return c256; \
- case APC_N_H ( 4096, h ) : return c4096; \
- case APC_N_H ( 65536, h ) : return c65536;
-
-/** Value used to represent "N/A" in adaptive proportion cutoff table */
-#define APC_NA 0
-
-/**
- * Look up value in adaptive proportion test cutoff table
- *
- * @v n N (window size)
- * @v h H (min-entropy)
- * @ret cutoff Cutoff
- *
- * This is the table of cutoff values defined in ANS X9.82 Part 2
- * (October 2011 Draft) Section 8.5.2.1.3.1.2.
- */
-static inline __attribute__ (( always_inline )) unsigned int
-adaptive_proportion_cutoff_lookup ( unsigned int n, unsigned int h ) {
- switch ( APC_N_H ( n, h ) ) {
- APC_TABLE_ROW ( 1, APC_NA, 51, 168, 2240, 33537 );
- APC_TABLE_ROW ( 2, APC_NA, 35, 100, 1193, 17053 );
- APC_TABLE_ROW ( 3, 10, 24, 61, 643, 8705 );
- APC_TABLE_ROW ( 4, 8, 16, 38, 354, 4473 );
- APC_TABLE_ROW ( 5, 6, 12, 25, 200, 2321 );
- APC_TABLE_ROW ( 6, 5, 9, 17, 117, 1220 );
- APC_TABLE_ROW ( 7, 4, 7, 15, 71, 653 );
- APC_TABLE_ROW ( 8, 4, 5, 9, 45, 358 );
- APC_TABLE_ROW ( 9, 3, 4, 7, 30, 202 );
- APC_TABLE_ROW ( 10, 3, 4, 5, 21, 118 );
- APC_TABLE_ROW ( 11, 2, 3, 4, 15, 71 );
- APC_TABLE_ROW ( 12, 2, 3, 4, 11, 45 );
- APC_TABLE_ROW ( 13, 2, 2, 3, 9, 30 );
- APC_TABLE_ROW ( 14, 2, 2, 3, 7, 21 );
- APC_TABLE_ROW ( 15, 1, 2, 2, 6, 15 );
- APC_TABLE_ROW ( 16, 1, 2, 2, 5, 11 );
- APC_TABLE_ROW ( 17, 1, 1, 2, 4, 9 );
- APC_TABLE_ROW ( 18, 1, 1, 2, 4, 7 );
- APC_TABLE_ROW ( 19, 1, 1, 1, 3, 6 );
- APC_TABLE_ROW ( 20, 1, 1, 1, 3, 5 );
- default:
- return APC_NA;
- }
-}
-
-/**
- * Calculate cutoff value for the adaptive proportion test
- *
- * @ret cutoff Cutoff value
- *
- * This is the cutoff value for the Adaptive Proportion Test defined
- * in ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.3.1.2.
- */
-static inline __attribute__ (( always_inline )) unsigned int
-adaptive_proportion_cutoff ( void ) {
- unsigned int h;
- unsigned int n;
- unsigned int cutoff;
-
- /* Look up cutoff value in cutoff table */
- n = ADAPTIVE_PROPORTION_WINDOW_SIZE;
- h = ( min_entropy_per_sample() / MIN_ENTROPY_SCALE );
- cutoff = adaptive_proportion_cutoff_lookup ( n, h );
-
- /* Fail unless cutoff value is a build-time constant */
- linker_assert ( __builtin_constant_p ( cutoff ),
- adaptive_proportion_cutoff_not_constant );
-
- /* Fail if cutoff value is N/A */
- linker_assert ( ( cutoff != APC_NA ),
- adaptive_proportion_cutoff_not_applicable );
-
- return cutoff;
-}
-
-/**
* Perform adaptive proportion test
*
* @v sample Noise sample
@@ -265,6 +171,8 @@
static noise_sample_t current_counted_sample;
static unsigned int sample_count = ADAPTIVE_PROPORTION_WINDOW_SIZE;
static unsigned int repetition_count;
+ unsigned int adaptive_proportion_cutoff =
+ entropy_source->adaptive_proportion_cutoff;
/* A = the sample value currently being counted
* B = the number of samples examined in this run of the test so far
@@ -312,7 +220,7 @@
* condition, because the test has
* detected a failure
*/
- if ( repetition_count > adaptive_proportion_cutoff() )
+ if ( repetition_count > adaptive_proportion_cutoff )
return -EPIPE_ADAPTIVE_PROPORTION_TEST;
}
@@ -322,6 +230,23 @@
}
/**
+ * Get noise sample
+ *
+ * @ret noise Noise sample
+ * @ret rc Return status code
+ *
+ * This is the GetNoise function defined in ANS X9.82 Part 2
+ * (October 2011 Draft) Section 6.5.2.
+ */
+int get_noise ( noise_sample_t *noise ) {
+
+ /* Sanity check */
+ assert ( entropy_source != NULL );
+
+ return entropy_source->get_noise ( noise );
+}
+
+/**
* Get entropy sample
*
* @ret entropy Entropy sample
@@ -334,6 +259,9 @@
static int rc = 0;
noise_sample_t noise;
+ /* Sanity check */
+ assert ( entropy_source != NULL );
+
/* Any failure is permanent */
if ( rc != 0 )
return rc;
@@ -358,31 +286,6 @@
}
/**
- * Calculate number of samples required for startup tests
- *
- * @ret num_samples Number of samples required
- *
- * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.5 requires
- * that at least one full cycle of the continuous tests must be
- * performed at start-up.
- */
-static inline __attribute__ (( always_inline )) unsigned int
-startup_test_count ( void ) {
- unsigned int num_samples;
-
- /* At least max(N,C) samples shall be generated by the noise
- * source for start-up testing.
- */
- num_samples = repetition_count_cutoff();
- if ( num_samples < adaptive_proportion_cutoff() )
- num_samples = adaptive_proportion_cutoff();
- linker_assert ( __builtin_constant_p ( num_samples ),
- startup_test_count_not_constant );
-
- return num_samples;
-}
-
-/**
* Create next nonce value
*
* @ret nonce Nonce
@@ -402,7 +305,7 @@
/**
* Obtain entropy input temporary buffer
*
- * @v num_samples Number of entropy samples
+ * @v min_entropy Min-entropy required
* @v tmp Temporary buffer
* @v tmp_len Length of temporary buffer
* @ret rc Return status code
@@ -412,11 +315,8 @@
* and condensing each entropy source output after each GetEntropy
* call) as defined in ANS X9.82 Part 4 (April 2011 Draft) Section
* 13.3.4.2.
- *
- * To minimise code size, the number of samples required is calculated
- * at compilation time.
*/
-int get_entropy_input_tmp ( unsigned int num_samples, uint8_t *tmp,
+int get_entropy_input_tmp ( min_entropy_t min_entropy, uint8_t *tmp,
size_t tmp_len ) {
static unsigned int startup_tested = 0;
struct {
@@ -424,6 +324,7 @@
entropy_sample_t sample;
} __attribute__ (( packed )) data;;
uint8_t df_buf[tmp_len];
+ min_entropy_t entropy_total;
unsigned int i;
int rc;
@@ -432,22 +333,20 @@
return rc;
/* Perform mandatory startup tests, if not yet performed */
- for ( ; startup_tested < startup_test_count() ; startup_tested++ ) {
+ for ( ; startup_tested < entropy_source->startup_test_count ;
+ startup_tested++ ) {
if ( ( rc = get_entropy ( &data.sample ) ) != 0 )
goto err_get_entropy;
}
- /* 3. entropy_total = 0
- *
- * (Nothing to do; the number of entropy samples required has
- * already been precalculated.)
- */
+ /* 3. entropy_total = 0 */
+ entropy_total = MIN_ENTROPY ( 0 );
/* 4. tmp = a fixed n-bit value, such as 0^n */
memset ( tmp, 0, tmp_len );
/* 5. While ( entropy_total < min_entropy ) */
- while ( num_samples-- ) {
+ while ( entropy_total < min_entropy ) {
/* 5.1. ( status, entropy_bitstring, assessed_entropy )
* = GetEntropy()
* 5.2. If status indicates an error, return ( status, Null )
@@ -466,11 +365,8 @@
for ( i = 0 ; i < tmp_len ; i++ )
tmp[i] ^= df_buf[i];
- /* 5.5. entropy_total = entropy_total + assessed_entropy
- *
- * (Nothing to do; the number of entropy samples
- * required has already been precalculated.)
- */
+ /* 5.5. entropy_total = entropy_total + assessed_entropy */
+ entropy_total += entropy_source->min_entropy_per_sample;
}
/* Disable entropy gathering */
diff --git a/src/crypto/null_entropy.c b/src/crypto/null_entropy.c
deleted file mode 100644
index d1e1a6f..0000000
--- a/src/crypto/null_entropy.c
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
- *
- * You can also choose to distribute this program under the terms of
- * the Unmodified Binary Distribution Licence (as given in the file
- * COPYING.UBDL), provided that you have satisfied its requirements.
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-/** @file
- *
- * Nonexistent entropy source
- *
- *
- * This source provides no entropy and must NOT be used in a
- * security-sensitive environment.
- */
-
-#include <ipxe/entropy.h>
-
-PROVIDE_ENTROPY_INLINE ( null, min_entropy_per_sample );
-PROVIDE_ENTROPY_INLINE ( null, entropy_enable );
-PROVIDE_ENTROPY_INLINE ( null, entropy_disable );
-PROVIDE_ENTROPY_INLINE ( null, get_noise );
diff --git a/src/include/ipxe/efi/efi_entropy.h b/src/include/ipxe/efi/efi_entropy.h
deleted file mode 100644
index 5b16fd7..0000000
--- a/src/include/ipxe/efi/efi_entropy.h
+++ /dev/null
@@ -1,35 +0,0 @@
-#ifndef _IPXE_EFI_ENTROPY_H
-#define _IPXE_EFI_ENTROPY_H
-
-/** @file
- *
- * EFI entropy source
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#include <stdint.h>
-
-#ifdef ENTROPY_EFI
-#define ENTROPY_PREFIX_efi
-#else
-#define ENTROPY_PREFIX_efi __efi_
-#endif
-
-/**
- * min-entropy per sample
- *
- * @ret min_entropy min-entropy of each sample
- */
-static inline __always_inline min_entropy_t
-ENTROPY_INLINE ( efi, min_entropy_per_sample ) ( void ) {
-
- /* We use essentially the same mechanism as for the BIOS
- * RTC-based entropy source, and so assume the same
- * min-entropy per sample.
- */
- return MIN_ENTROPY ( 1.3 );
-}
-
-#endif /* _IPXE_EFI_ENTROPY_H */
diff --git a/src/include/ipxe/entropy.h b/src/include/ipxe/entropy.h
index d2e3ce5..b2343ac 100644
--- a/src/include/ipxe/entropy.h
+++ b/src/include/ipxe/entropy.h
@@ -12,40 +12,11 @@
#include <stdint.h>
#include <string.h>
#include <assert.h>
-#include <ipxe/api.h>
#include <ipxe/hash_df.h>
#include <ipxe/sha256.h>
+#include <ipxe/tables.h>
#include <config/entropy.h>
-/**
- * Calculate static inline entropy API function name
- *
- * @v _prefix Subsystem prefix
- * @v _api_func API function
- * @ret _subsys_func Subsystem API function
- */
-#define ENTROPY_INLINE( _subsys, _api_func ) \
- SINGLE_API_INLINE ( ENTROPY_PREFIX_ ## _subsys, _api_func )
-
-/**
- * Provide a entropy API implementation
- *
- * @v _prefix Subsystem prefix
- * @v _api_func API function
- * @v _func Implementing function
- */
-#define PROVIDE_ENTROPY( _subsys, _api_func, _func ) \
- PROVIDE_SINGLE_API ( ENTROPY_PREFIX_ ## _subsys, _api_func, _func )
-
-/**
- * Provide a static inline entropy API implementation
- *
- * @v _prefix Subsystem prefix
- * @v _api_func API function
- */
-#define PROVIDE_ENTROPY_INLINE( _subsys, _api_func ) \
- PROVIDE_SINGLE_API_INLINE ( ENTROPY_PREFIX_ ## _subsys, _api_func )
-
/** A noise sample */
typedef uint8_t noise_sample_t;
@@ -71,56 +42,93 @@
#define MIN_ENTROPY( bits ) \
( ( min_entropy_t ) ( (bits) * MIN_ENTROPY_SCALE ) )
-/* Include all architecture-independent entropy API headers */
-#include <ipxe/null_entropy.h>
-#include <ipxe/efi/efi_entropy.h>
-#include <ipxe/linux/linux_entropy.h>
+/** An entropy source */
+struct entropy_source {
+ /** Name */
+ const char *name;
+ /**
+ * min-entropy per sample
+ *
+ * min-entropy is defined in ANS X9.82 Part 1-2006 Section 8.3 and in
+ * NIST SP 800-90 Appendix C.3 as
+ *
+ * H_min = -log2 ( p_max )
+ *
+ * where p_max is the probability of the most likely sample value.
+ *
+ * Filled in by entropy_init().
+ */
+ min_entropy_t min_entropy_per_sample;
+ /**
+ * Repetition count test cutoff value
+ *
+ * This is the cutoff value for the Repetition Count Test
+ * defined in ANS X9.82 Part 2 (October 2011 Draft) Section
+ * 8.5.2.1.2.
+ *
+ * Filled in by entropy_init().
+ */
+ unsigned int repetition_count_cutoff;
+ /**
+ * Adaptive proportion test cutoff value
+ *
+ * This is the cutoff value for the Adaptive Proportion Test
+ * defined in ANS X9.82 Part 2 (October 2011 Draft) Section
+ * 8.5.2.1.3.1.2.
+ *
+ * Filled in by entropy_init().
+ */
+ unsigned int adaptive_proportion_cutoff;
+ /**
+ * Startup test count
+ *
+ * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.5
+ * requires that at least one full cycle of the continuous
+ * tests must be performed at start-up.
+ */
+ unsigned int startup_test_count;
+ /**
+ * Enable entropy gathering
+ *
+ * @ret rc Return status code
+ */
+ int ( * enable ) ( void );
+ /**
+ * Disable entropy gathering
+ *
+ */
+ void ( * disable ) ( void );
+ /**
+ * Get noise sample
+ *
+ * @ret noise Noise sample
+ * @ret rc Return status code
+ *
+ * This is the GetNoise function defined in ANS X9.82 Part 2
+ * (October 2011 Draft) Section 6.5.2.
+ */
+ int ( * get_noise ) ( noise_sample_t *noise );
+};
-/* Include all architecture-dependent entropy API headers */
-#include <bits/entropy.h>
+/** Entropy source table */
+#define ENTROPY_SOURCES __table ( struct entropy_source, "entropy_sources" )
-/**
- * Enable entropy gathering
+/** Declare an entropy source */
+#define __entropy_source( order ) __table_entry ( ENTROPY_SOURCES, order )
+
+/** @defgroup entropy_source_order Entropy source order
*
- * @ret rc Return status code
+ * @{
*/
-int entropy_enable ( void );
-/**
- * Disable entropy gathering
- *
- */
-void entropy_disable ( void );
+#define ENTROPY_PREFERRED 01 /**< Preferred entropy source */
+#define ENTROPY_NORMAL 02 /**< Normal entropy source */
+#define ENTROPY_FALLBACK 03 /**< Fallback entropy source */
-/**
- * min-entropy per sample
- *
- * @ret min_entropy min-entropy of each sample
- *
- * min-entropy is defined in ANS X9.82 Part 1-2006 Section 8.3 and in
- * NIST SP 800-90 Appendix C.3 as
- *
- * H_min = -log2 ( p_max )
- *
- * where p_max is the probability of the most likely sample value.
- *
- * This must be a compile-time constant.
- */
-min_entropy_t min_entropy_per_sample ( void );
+/** @} */
-/**
- * Get noise sample
- *
- * @ret noise Noise sample
- * @ret rc Return status code
- *
- * This is the GetNoise function defined in ANS X9.82 Part 2
- * (October 2011 Draft) Section 6.5.2.
- */
-int get_noise ( noise_sample_t *noise );
-
-extern int get_entropy_input_tmp ( unsigned int num_samples,
- uint8_t *tmp, size_t tmp_len );
+extern int get_entropy_input_tmp ( min_entropy_t min_entropy, uint8_t *tmp,
+ size_t tmp_len );
/** Use SHA-256 as the underlying hash algorithm for Hash_df
*
@@ -145,8 +153,9 @@
* each entropy source output after each GetEntropy call) as defined
* in ANS X9.82 Part 4 (April 2011 Draft) Section 13.3.4.2.
*
- * To minimise code size, the number of samples required is calculated
- * at compilation time.
+ * This function is inlined to avoid unnecessarily linking in
+ * hash_df(), since the length inputs are always compile-time
+ * constants.
*/
static inline __attribute__ (( always_inline )) int
get_entropy_input ( unsigned int min_entropy_bits, void *data, size_t min_len,
@@ -154,41 +163,16 @@
size_t tmp_len = ( ( ( min_entropy_bits * 2 ) + 7 ) / 8 );
uint8_t tmp_buf[ tmp_len ];
uint8_t *tmp = ( ( tmp_len > max_len ) ? tmp_buf : data );
- double min_samples;
- unsigned int num_samples;
unsigned int n;
int rc;
- /* Sanity checks */
- linker_assert ( ( min_entropy_per_sample() <=
- MIN_ENTROPY ( 8 * sizeof ( noise_sample_t ) ) ),
- min_entropy_per_sample_is_impossibly_high );
+ /* Sanity check */
linker_assert ( ( min_entropy_bits <= ( 8 * max_len ) ),
entropy_buffer_too_small );
/* Round up minimum entropy to an integral number of bytes */
min_entropy_bits = ( ( min_entropy_bits + 7 ) & ~7 );
- /* Calculate number of samples required to contain sufficient entropy */
- min_samples = ( MIN_ENTROPY ( min_entropy_bits ) /
- min_entropy_per_sample() );
-
- /* Round up to a whole number of samples. We don't have the
- * ceil() function available, so do the rounding by hand.
- */
- num_samples = min_samples;
- if ( num_samples < min_samples )
- num_samples++;
- linker_assert ( ( num_samples >= min_samples ), rounding_error );
-
- /* Floating-point operations are not allowed in iPXE since we
- * never set up a suitable environment. Abort the build
- * unless the calculated number of samples is a compile-time
- * constant.
- */
- linker_assert ( __builtin_constant_p ( num_samples ),
- num_samples_not_constant );
-
/* (Unnumbered). The output length of the hash function shall
* meet or exceed the security strength indicated by the
* min_entropy parameter.
@@ -218,8 +202,10 @@
linker_assert ( __builtin_constant_p ( tmp_len ),
tmp_len_not_constant );
linker_assert ( ( n == ( 8 * tmp_len ) ), tmp_len_mismatch );
- if ( ( rc = get_entropy_input_tmp ( num_samples, tmp, tmp_len ) ) != 0 )
+ if ( ( rc = get_entropy_input_tmp ( MIN_ENTROPY ( min_entropy_bits ),
+ tmp, tmp_len ) ) != 0 ) {
return rc;
+ }
/* 6. If ( n < min_length ), then tmp = tmp || 0^(min_length-n)
* 7. If ( n > max_length ), then tmp = df ( tmp, max_length )
@@ -242,4 +228,229 @@
}
}
+/**
+ * Calculate cutoff value for the repetition count test
+ *
+ * @v min_entropy_per_sample Min-entropy per sample
+ * @ret cutoff Cutoff value
+ *
+ * This is the cutoff value for the Repetition Count Test defined in
+ * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.2.
+ */
+static inline __attribute__ (( always_inline )) unsigned int
+entropy_repetition_count_cutoff ( min_entropy_t min_entropy_per_sample ) {
+ double max_repetitions;
+ unsigned int cutoff;
+
+ /* The cutoff formula for the repetition test is:
+ *
+ * C = ( 1 + ( -log2(W) / H_min ) )
+ *
+ * where W is set at 2^(-30) (in ANS X9.82 Part 2 (October
+ * 2011 Draft) Section 8.5.2.1.3.1).
+ */
+ max_repetitions = ( 1 + ( MIN_ENTROPY ( 30 ) /
+ min_entropy_per_sample ) );
+
+ /* Round up to a whole number of repetitions. We don't have
+ * the ceil() function available, so do the rounding by hand.
+ */
+ cutoff = max_repetitions;
+ if ( cutoff < max_repetitions )
+ cutoff++;
+ linker_assert ( ( cutoff >= max_repetitions ), rounding_error );
+
+ /* Floating-point operations are not allowed in iPXE since we
+ * never set up a suitable environment. Abort the build
+ * unless the calculated number of repetitions is a
+ * compile-time constant.
+ */
+ linker_assert ( __builtin_constant_p ( cutoff ),
+ repetition_count_cutoff_not_constant );
+
+ return cutoff;
+}
+
+/**
+ * Window size for the adaptive proportion test
+ *
+ * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.3.1.1 allows
+ * five possible window sizes: 16, 64, 256, 4096 and 65536.
+ *
+ * We expect to generate relatively few (<256) entropy samples during
+ * a typical iPXE run; the use of a large window size would mean that
+ * the test would never complete a single cycle. We use a window size
+ * of 64, which is the smallest window size that permits values of
+ * H_min down to one bit per sample.
+ */
+#define ADAPTIVE_PROPORTION_WINDOW_SIZE 64
+
+/**
+ * Combine adaptive proportion test window size and min-entropy
+ *
+ * @v n N (window size)
+ * @v h H (min-entropy)
+ * @ret n_h (N,H) combined value
+ */
+#define APC_N_H( n, h ) ( ( (n) << 8 ) | (h) )
+
+/**
+ * Define a row of the adaptive proportion cutoff table
+ *
+ * @v h H (min-entropy)
+ * @v c16 Cutoff for N=16
+ * @v c64 Cutoff for N=64
+ * @v c256 Cutoff for N=256
+ * @v c4096 Cutoff for N=4096
+ * @v c65536 Cutoff for N=65536
+ */
+#define APC_TABLE_ROW( h, c16, c64, c256, c4096, c65536) \
+ case APC_N_H ( 16, h ) : return c16; \
+ case APC_N_H ( 64, h ) : return c64; \
+ case APC_N_H ( 256, h ) : return c256; \
+ case APC_N_H ( 4096, h ) : return c4096; \
+ case APC_N_H ( 65536, h ) : return c65536;
+
+/** Value used to represent "N/A" in adaptive proportion cutoff table */
+#define APC_NA 0
+
+/**
+ * Look up value in adaptive proportion test cutoff table
+ *
+ * @v n N (window size)
+ * @v h H (min-entropy)
+ * @ret cutoff Cutoff
+ *
+ * This is the table of cutoff values defined in ANS X9.82 Part 2
+ * (October 2011 Draft) Section 8.5.2.1.3.1.2.
+ */
+static inline __attribute__ (( always_inline )) unsigned int
+entropy_adaptive_proportion_cutoff_lookup ( unsigned int n, unsigned int h ) {
+ switch ( APC_N_H ( n, h ) ) {
+ APC_TABLE_ROW ( 1, APC_NA, 51, 168, 2240, 33537 );
+ APC_TABLE_ROW ( 2, APC_NA, 35, 100, 1193, 17053 );
+ APC_TABLE_ROW ( 3, 10, 24, 61, 643, 8705 );
+ APC_TABLE_ROW ( 4, 8, 16, 38, 354, 4473 );
+ APC_TABLE_ROW ( 5, 6, 12, 25, 200, 2321 );
+ APC_TABLE_ROW ( 6, 5, 9, 17, 117, 1220 );
+ APC_TABLE_ROW ( 7, 4, 7, 15, 71, 653 );
+ APC_TABLE_ROW ( 8, 4, 5, 9, 45, 358 );
+ APC_TABLE_ROW ( 9, 3, 4, 7, 30, 202 );
+ APC_TABLE_ROW ( 10, 3, 4, 5, 21, 118 );
+ APC_TABLE_ROW ( 11, 2, 3, 4, 15, 71 );
+ APC_TABLE_ROW ( 12, 2, 3, 4, 11, 45 );
+ APC_TABLE_ROW ( 13, 2, 2, 3, 9, 30 );
+ APC_TABLE_ROW ( 14, 2, 2, 3, 7, 21 );
+ APC_TABLE_ROW ( 15, 1, 2, 2, 6, 15 );
+ APC_TABLE_ROW ( 16, 1, 2, 2, 5, 11 );
+ APC_TABLE_ROW ( 17, 1, 1, 2, 4, 9 );
+ APC_TABLE_ROW ( 18, 1, 1, 2, 4, 7 );
+ APC_TABLE_ROW ( 19, 1, 1, 1, 3, 6 );
+ APC_TABLE_ROW ( 20, 1, 1, 1, 3, 5 );
+ default:
+ return APC_NA;
+ }
+}
+
+/**
+ * Calculate cutoff value for the adaptive proportion test
+ *
+ * @v min_entropy_per_sample Min-entropy per sample
+ * @ret cutoff Cutoff value
+ *
+ * This is the cutoff value for the Adaptive Proportion Test defined
+ * in ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.3.1.2.
+ */
+static inline __attribute__ (( always_inline )) unsigned int
+entropy_adaptive_proportion_cutoff ( min_entropy_t min_entropy_per_sample ) {
+ unsigned int h;
+ unsigned int n;
+ unsigned int cutoff;
+
+ /* Look up cutoff value in cutoff table */
+ n = ADAPTIVE_PROPORTION_WINDOW_SIZE;
+ h = ( min_entropy_per_sample / MIN_ENTROPY_SCALE );
+ cutoff = entropy_adaptive_proportion_cutoff_lookup ( n, h );
+
+ /* Fail unless cutoff value is a compile-time constant */
+ linker_assert ( __builtin_constant_p ( cutoff ),
+ adaptive_proportion_cutoff_not_constant );
+
+ /* Fail if cutoff value is N/A */
+ linker_assert ( ( cutoff != APC_NA ),
+ adaptive_proportion_cutoff_not_applicable );
+
+ return cutoff;
+}
+
+/**
+ * Calculate number of samples required for startup tests
+ *
+ * @v repetition_count_cutoff Repetition count test cutoff value
+ * @v adaptive_proportion_cutoff Adaptive proportion test cutoff value
+ * @ret num_samples Number of samples required
+ *
+ * ANS X9.82 Part 2 (October 2011 Draft) Section 8.5.2.1.5 requires
+ * that at least one full cycle of the continuous tests must be
+ * performed at start-up.
+ */
+static inline __attribute__ (( always_inline )) unsigned int
+entropy_startup_test_count ( unsigned int repetition_count_cutoff,
+ unsigned int adaptive_proportion_cutoff ) {
+ unsigned int num_samples;
+
+ /* At least max(N,C) samples shall be generated by the noise
+ * source for start-up testing.
+ */
+ num_samples = repetition_count_cutoff;
+ if ( num_samples < adaptive_proportion_cutoff )
+ num_samples = adaptive_proportion_cutoff;
+ linker_assert ( __builtin_constant_p ( num_samples ),
+ startup_test_count_not_constant );
+
+ return num_samples;
+}
+
+/**
+ * Initialise entropy source
+ *
+ * @v source Entropy source
+ * @v min_entropy_per_sample Min-entropy per sample
+ *
+ * The cutoff value calculations for the repetition count test and the
+ * adaptive proportion test are provided as static inline functions
+ * since the results will always be compile-time constants.
+ */
+static inline __attribute__ (( always_inline )) void
+entropy_init ( struct entropy_source *source,
+ min_entropy_t min_entropy_per_sample ) {
+ unsigned int repetition_count_cutoff;
+ unsigned int adaptive_proportion_cutoff;
+ unsigned int startup_test_count;
+
+ /* Sanity check */
+ linker_assert ( ( min_entropy_per_sample <=
+ MIN_ENTROPY ( 8 * sizeof ( noise_sample_t ) ) ),
+ min_entropy_per_sample_is_impossibly_high );
+
+ /* Calculate test cutoff values */
+ repetition_count_cutoff =
+ entropy_repetition_count_cutoff ( min_entropy_per_sample );
+ adaptive_proportion_cutoff =
+ entropy_adaptive_proportion_cutoff ( min_entropy_per_sample );
+ startup_test_count =
+ entropy_startup_test_count ( repetition_count_cutoff,
+ adaptive_proportion_cutoff );
+
+ /* Record min-entropy per sample and test cutoff values */
+ source->min_entropy_per_sample = min_entropy_per_sample;
+ source->repetition_count_cutoff = repetition_count_cutoff;
+ source->adaptive_proportion_cutoff = adaptive_proportion_cutoff;
+ source->startup_test_count = startup_test_count;
+}
+
+extern int entropy_enable ( void );
+extern void entropy_disable ( void );
+extern int get_noise ( noise_sample_t *noise );
+
#endif /* _IPXE_ENTROPY_H */
diff --git a/src/include/ipxe/linux/linux_entropy.h b/src/include/ipxe/linux/linux_entropy.h
deleted file mode 100644
index ea8c1f1..0000000
--- a/src/include/ipxe/linux/linux_entropy.h
+++ /dev/null
@@ -1,34 +0,0 @@
-#ifndef _IPXE_LINUX_ENTROPY_H
-#define _IPXE_LINUX_ENTROPY_H
-
-/** @file
- *
- * /dev/random-based entropy source
- *
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#ifdef ENTROPY_LINUX
-#define ENTROPY_PREFIX_linux
-#else
-#define ENTROPY_PREFIX_linux __linux_
-#endif
-
-/**
- * min-entropy per sample
- *
- * @ret min_entropy min-entropy of each sample
- */
-static inline __always_inline min_entropy_t
-ENTROPY_INLINE ( linux, min_entropy_per_sample ) ( void ) {
-
- /* linux_get_noise() reads a single byte from /dev/random,
- * which is supposed to block until a sufficient amount of
- * entropy is available. We therefore assume that each sample
- * contains exactly 8 bits of entropy.
- */
- return MIN_ENTROPY ( 8.0 );
-}
-
-#endif /* _IPXE_LINUX_ENTROPY_H */
diff --git a/src/include/ipxe/null_entropy.h b/src/include/ipxe/null_entropy.h
deleted file mode 100644
index 5a6bb62..0000000
--- a/src/include/ipxe/null_entropy.h
+++ /dev/null
@@ -1,52 +0,0 @@
-#ifndef _IPXE_NULL_ENTROPY_H
-#define _IPXE_NULL_ENTROPY_H
-
-/** @file
- *
- * Nonexistent entropy source
- *
- * This source provides no entropy and must NOT be used in a
- * security-sensitive environment.
- */
-
-FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
-#include <stdint.h>
-
-#ifdef ENTROPY_NULL
-#define ENTROPY_PREFIX_null
-#else
-#define ENTROPY_PREFIX_null __null_
-#endif
-
-static inline __always_inline int
-ENTROPY_INLINE ( null, entropy_enable ) ( void ) {
- /* Do nothing */
- return 0;
-}
-
-static inline __always_inline void
-ENTROPY_INLINE ( null, entropy_disable ) ( void ) {
- /* Do nothing */
-}
-
-static inline __always_inline min_entropy_t
-ENTROPY_INLINE ( null, min_entropy_per_sample ) ( void ) {
- /* Actual amount of min-entropy is zero. To avoid
- * division-by-zero errors and to allow compilation of
- * entropy-consuming code, pretend to have 1 bit of entropy in
- * each sample.
- */
- return MIN_ENTROPY ( 1.0 );
-}
-
-static inline __always_inline int
-ENTROPY_INLINE ( null, get_noise ) ( noise_sample_t *noise ) {
-
- /* All sample values are constant */
- *noise = 0x01;
-
- return 0;
-}
-
-#endif /* _IPXE_NULL_ENTROPY_H */
diff --git a/src/interface/efi/efi_entropy.c b/src/interface/efi/efi_entropy.c
index 1e8ddfb..e5c3935 100644
--- a/src/interface/efi/efi_entropy.c
+++ b/src/interface/efi/efi_entropy.c
@@ -36,6 +36,8 @@
*
*/
+struct entropy_source efi_entropy __entropy_source ( ENTROPY_NORMAL );
+
/** Random number generator protocol */
static EFI_RNG_PROTOCOL *efirng;
EFI_REQUEST_PROTOCOL ( EFI_RNG_PROTOCOL, &efirng );
@@ -91,6 +93,12 @@
return rc;
}
+ /* We use essentially the same mechanism as for the BIOS
+ * RTC-based entropy source, and so assume the same
+ * min-entropy per sample.
+ */
+ entropy_init ( &efi_entropy, MIN_ENTROPY ( 1.3 ) );
+
return 0;
}
@@ -235,7 +243,10 @@
return 0;
}
-PROVIDE_ENTROPY_INLINE ( efi, min_entropy_per_sample );
-PROVIDE_ENTROPY ( efi, entropy_enable, efi_entropy_enable );
-PROVIDE_ENTROPY ( efi, entropy_disable, efi_entropy_disable );
-PROVIDE_ENTROPY ( efi, get_noise, efi_get_noise );
+/** EFI entropy source */
+struct entropy_source efi_entropy __entropy_source ( ENTROPY_NORMAL ) = {
+ .name = "efi",
+ .enable = efi_entropy_enable,
+ .disable = efi_entropy_disable,
+ .get_noise = efi_get_noise,
+};
diff --git a/src/interface/linux/linux_entropy.c b/src/interface/linux/linux_entropy.c
index 257e993..f249697 100644
--- a/src/interface/linux/linux_entropy.c
+++ b/src/interface/linux/linux_entropy.c
@@ -34,6 +34,8 @@
#include <ipxe/linux_api.h>
#include <ipxe/entropy.h>
+struct entropy_source linux_entropy __entropy_source ( ENTROPY_NORMAL );
+
/** Entropy source filename */
static const char entropy_filename[] = "/dev/random";
@@ -55,6 +57,13 @@
return entropy_fd;
}
+ /* linux_get_noise() reads a single byte from /dev/random,
+ * which is supposed to block until a sufficient amount of
+ * entropy is available. We therefore assume that each sample
+ * contains exactly 8 bits of entropy.
+ */
+ entropy_init ( &linux_entropy, MIN_ENTROPY ( 8.0 ) );
+
return 0;
}
@@ -95,7 +104,10 @@
return 0;
}
-PROVIDE_ENTROPY_INLINE ( linux, min_entropy_per_sample );
-PROVIDE_ENTROPY ( linux, entropy_enable, linux_entropy_enable );
-PROVIDE_ENTROPY ( linux, entropy_disable, linux_entropy_disable );
-PROVIDE_ENTROPY ( linux, get_noise, linux_get_noise );
+/** Linux entropy source */
+struct entropy_source linux_entropy __entropy_source ( ENTROPY_NORMAL ) = {
+ .name = "linux",
+ .enable = linux_entropy_enable,
+ .disable = linux_entropy_disable,
+ .get_noise = linux_get_noise,
+};
