Messages in this thread Patch in this message | | | Date | Thu, 24 Mar 2005 14:30:23 +1000 | From | David McCullough <> | Subject | [PATCH] API for true Random Number Generators to add entropy (2.4.29) |
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Hi all,
Here is a small patch for 2.4.29 that adds a routine:
add_true_randomness(__u32 *buf, int nwords);
so that true random number generator device drivers can add a entropy to the system. Drivers that use this can be found in the latest release of ocf-linux, an asynchronous crypto implementation for linux based on the *BSD Cryptographic Framework.
http://ocf-linux.sourceforge.net/
Adding this can dramatically improve the performance of /dev/random on small embedded systems which do not generate much entropy.
Cheers, Davidm
Signed-off-by: David McCullough <davidm@snapgear.com>
Index: linux-2.4.29/include/linux/random.h =================================================================== RCS file: /cvs/sw/linux-2.4.29/include/linux/random.h,v retrieving revision 1.1.1.1 retrieving revision 1.3 diff -u -r1.1.1.1 -r1.3 --- linux-2.4.29/include/linux/random.h 9 Jul 2001 00:39:16 -0000 1.1.1.1 +++ linux-2.4.29/include/linux/random.h 18 Mar 2005 04:33:35 -0000 1.3 @@ -52,6 +52,7 @@ extern void add_mouse_randomness(__u32 mouse_data); extern void add_interrupt_randomness(int irq); extern void add_blkdev_randomness(int major); +extern void add_true_randomness(__u32 *buf, int nwords); extern void get_random_bytes(void *buf, int nbytes); void generate_random_uuid(unsigned char uuid_out[16]); Index: linux-2.4.29/drivers/char/random.c =================================================================== RCS file: /cvs/sw/linux-2.4.29/drivers/char/random.c,v retrieving revision 1.1.1.9 retrieving revision 1.11 diff -u -r1.1.1.9 -r1.11 --- linux-2.4.29/drivers/char/random.c 4 Feb 2005 00:28:36 -0000 1.1.1.9 +++ linux-2.4.29/drivers/char/random.c 18 Mar 2005 04:33:35 -0000 1.11 @@ -842,6 +837,39 @@ add_timer_randomness(blkdev_timer_state[major], 0x200+major); } +/* + * provide a mechanism for HW RNG's to add entropy that is of + * very good quality. + */ +void add_true_randomness(__u32 *buf, int nwords) +{ + struct entropy_store *r; + int wakeup_check = 0; + + + if (!random_state || !sec_random_state) + return; + + /* + * if we have too much entropy, put some in the secondary pool + */ + r = random_state; + if (r->entropy_count >= r->poolinfo.POOLBITS) + r = sec_random_state; + else + wakeup_check = (r->entropy_count < random_read_wakeup_thresh); + + add_entropy_words(r, buf, nwords); + credit_entropy_store(r, nwords * 32); + + /* + * wakeup if we added enough entropy to cross the threshold + */ + if (wakeup_check && r->entropy_count >= random_read_wakeup_thresh) + wake_up_interruptible(&random_read_wait); +} +EXPORT_SYMBOL(add_true_randomness); + /****************************************************************** * * Hash function definition -- David McCullough, davidm@snapgear.com Ph:+61 7 34352815 http://www.SnapGear.com Custom Embedded Solutions + Security Fx:+61 7 38913630 http://www.uCdot.org - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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