diff options
| -rw-r--r-- | crypto/Makefile | 1 | ||||
| -rw-r--r-- | crypto/jitterentropy.c | 30 |
2 files changed, 26 insertions, 5 deletions
diff --git a/crypto/Makefile b/crypto/Makefile index 83b3c4496ec7..c84203572477 100644 --- a/crypto/Makefile +++ b/crypto/Makefile @@ -97,7 +97,6 @@ obj-$(CONFIG_CRYPTO_842) += 842.o obj-$(CONFIG_CRYPTO_RNG2) += rng.o obj-$(CONFIG_CRYPTO_ANSI_CPRNG) += ansi_cprng.o obj-$(CONFIG_CRYPTO_DRBG) += drbg.o -CFLAGS_jitterentropy.o = -O0 obj-$(CONFIG_CRYPTO_JITTERENTROPY) += jitterentropy.o obj-$(CONFIG_CRYPTO_TEST) += tcrypt.o obj-$(CONFIG_CRYPTO_GHASH) += ghash-generic.o diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c index a60147e4bb3f..d3c30452edee 100644 --- a/crypto/jitterentropy.c +++ b/crypto/jitterentropy.c @@ -57,10 +57,6 @@ #include <linux/crypto.h> #include <crypto/internal/rng.h> -#ifdef __OPTIMIZE__ - #error "The CPU Jitter random number generator must not be compiled with optimizations. See documentation. Use the compiler switch -O0 for compiling jitterentropy.c." -#endif - /* The entropy pool */ struct rand_data { /* all data values that are vital to maintain the security @@ -188,6 +184,20 @@ static __u64 jent_loop_shuffle(struct rand_data *ec, * Noise sources ***************************************************************************/ +/* + * The disabling of the optimizations is performed as documented and assessed + * thoroughly in http://www.chronox.de/jent.html. However, instead of disabling + * the optimization of the entire C file, only the main functions the jitter is + * measured for are not optimized. These functions include the noise sources as + * well as the main functions triggering the noise sources. As the time + * measurement is done from one invocation of the jitter noise source to the + * next, even the execution jitter of the code invoking the noise sources + * contribute to the overall randomness as well. The behavior of the RNG and the + * statistical characteristics when only the mentioned functions are not + * optimized is almost equal to the a completely non-optimized RNG compilation + * as tested with the test tools provided at the initially mentioned web site. + */ + /** * CPU Jitter noise source -- this is the noise source based on the CPU * execution time jitter @@ -222,6 +232,8 @@ static __u64 jent_loop_shuffle(struct rand_data *ec, * * @return Number of loops the folding operation is performed */ +#pragma GCC push_options +#pragma GCC optimize ("-O0") static __u64 jent_fold_time(struct rand_data *ec, __u64 time, __u64 *folded, __u64 loop_cnt) { @@ -251,6 +263,7 @@ static __u64 jent_fold_time(struct rand_data *ec, __u64 time, *folded = new; return fold_loop_cnt; } +#pragma GCC pop_options /** * Memory Access noise source -- this is a noise source based on variations in @@ -279,6 +292,8 @@ static __u64 jent_fold_time(struct rand_data *ec, __u64 time, * * @return Number of memory access operations */ +#pragma GCC push_options +#pragma GCC optimize ("-O0") static unsigned int jent_memaccess(struct rand_data *ec, __u64 loop_cnt) { unsigned char *tmpval = NULL; @@ -318,6 +333,7 @@ static unsigned int jent_memaccess(struct rand_data *ec, __u64 loop_cnt) } return i; } +#pragma GCC pop_options /*************************************************************************** * Start of entropy processing logic @@ -366,6 +382,8 @@ static void jent_stuck(struct rand_data *ec, __u64 current_delta) * * @return One random bit */ +#pragma GCC push_options +#pragma GCC optimize ("-O0") static __u64 jent_measure_jitter(struct rand_data *ec) { __u64 time = 0; @@ -395,6 +413,7 @@ static __u64 jent_measure_jitter(struct rand_data *ec) return data; } +#pragma GCC pop_options /** * Von Neuman unbias as explained in RFC 4086 section 4.2. As shown in the @@ -495,6 +514,8 @@ static void jent_stir_pool(struct rand_data *entropy_collector) * Input: * @ec Reference to entropy collector */ +#pragma GCC push_options +#pragma GCC optimize ("-O0") static void jent_gen_entropy(struct rand_data *ec) { unsigned int k = 0; @@ -556,6 +577,7 @@ static void jent_gen_entropy(struct rand_data *ec) if (ec->stir) jent_stir_pool(ec); } +#pragma GCC pop_options /** * The continuous test required by FIPS 140-2 -- the function automatically |