Add support for the hardware random number generator on the Hifn 7811
and 795x. This was present in the driver before, but disabled due to problems with the actual randomness of generated numbers on the ubiquitious 7900-series parts. The code here is far, far more conservative than anyone else's driver for this RNG is -- but I believe that conservatism is called for, because the 79xx RNG design is missing a number of pieces from Hifn's "reference" 6500 RNG, and thus the numbers it generates must be treated with some care. Support for the 7811 RNG (which is a full-fledged 6500 type generator) is pretty much the same here as in other variants of this driver, except that it uses Hifn's "worst case" estimate of actual entropy per output bit, so it will accumulate bits much more slowly. The 7811 support is untested.
This commit is contained in:
tls
parent
15cb9441e1
commit
eb5ea4a10b
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@ -1,4 +1,4 @@
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/* $NetBSD: hifn7751.c,v 1.24 2005/10/15 04:31:20 tls Exp $ */
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/* $NetBSD: hifn7751.c,v 1.25 2005/10/15 08:58:15 tls Exp $ */
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/* $FreeBSD: hifn7751.c,v 1.5.2.7 2003/10/08 23:52:00 sam Exp $ */
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/* $OpenBSD: hifn7751.c,v 1.140 2003/08/01 17:55:54 deraadt Exp $ */
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@ -48,7 +48,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: hifn7751.c,v 1.24 2005/10/15 04:31:20 tls Exp $");
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__KERNEL_RCSID(0, "$NetBSD: hifn7751.c,v 1.25 2005/10/15 08:58:15 tls Exp $");
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#include "rnd.h"
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#include "opencrypto.h"
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@ -88,7 +88,6 @@ __KERNEL_RCSID(0, "$NetBSD: hifn7751.c,v 1.24 2005/10/15 04:31:20 tls Exp $");
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#undef HIFN_DEBUG
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#ifdef __NetBSD__
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#define HIFN_NO_RNG /* until statistically tested */
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#define M_DUP_PKTHDR M_COPY_PKTHDR /* XXX */
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#endif
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@ -149,9 +148,7 @@ static int hifn_dmamap_load_src(struct hifn_softc *,
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static int hifn_dmamap_load_dst(struct hifn_softc *,
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struct hifn_command *);
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static int hifn_init_pubrng(struct hifn_softc *);
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#ifndef HIFN_NO_RNG
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static static void hifn_rng(void *);
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#endif
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static void hifn_rng(void *);
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static void hifn_tick(void *);
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static void hifn_abort(struct hifn_softc *);
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static void hifn_alloc_slot(struct hifn_softc *, int *, int *, int *,
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@ -512,20 +509,41 @@ hifn_init_pubrng(struct hifn_softc *sc)
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READ_REG_1(sc, HIFN_1_RNG_CONFIG) |
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HIFN_RNGCFG_ENA);
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/*
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* The Hifn RNG documentation states that at their
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* recommended "conservative" RNG config values,
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* the RNG must warm up for 0.4s before providing
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* data that meet their worst-case estimate of 0.06
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* bits of random data per output register bit.
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*/
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DELAY(4000);
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#ifdef __NetBSD__
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/*
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* XXX Careful! The use of RND_FLAG_NO_ESTIMATE
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* XXX here is unobvious: we later feed raw bits
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* XXX into the "entropy pool" with rnd_add_data,
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* XXX explicitly supplying an entropy estimate.
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* XXX In this context, NO_ESTIMATE serves only
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* XXX to prevent rnd_add_data from trying to
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* XXX use the *time at which we added the data*
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* XXX as entropy, which is not a good idea since
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* XXX we add data periodically from a callout.
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*/
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rnd_attach_source(&sc->sc_rnd_source, sc->sc_dv.dv_xname,
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RND_TYPE_RNG, RND_FLAG_NO_ESTIMATE);
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#endif
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sc->sc_rngfirst = 1;
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if (hz >= 100)
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sc->sc_rnghz = hz / 100;
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else
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sc->sc_rnghz = 1;
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#ifndef HIFN_NO_RNG
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#ifdef __OpenBSD__
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timeout_set(&sc->sc_rngto, hifn_rng, sc);
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timeout_add(&sc->sc_rngto, sc->sc_rnghz);
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#else /* !__OpenBSD__ */
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callout_init(&sc->sc_rngto);
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callout_reset(&sc->sc_rngto, sc->sc_rnghz, hifn_rng, sc);
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#endif /* !__OpenBSD__ */
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#endif /* HIFN_NO_RNG */
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}
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/* Enable public key engine, if available */
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@ -535,20 +553,26 @@ hifn_init_pubrng(struct hifn_softc *sc)
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WRITE_REG_1(sc, HIFN_1_DMA_IER, sc->sc_dmaier);
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}
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/* Call directly into the RNG once to prime the pool. */
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hifn_rng(sc); /* Sets callout/timeout at end */
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return (0);
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}
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#ifndef HIFN_NO_RNG
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static void
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hifn_rng(void *vsc)
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{
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#ifndef __NetBSD__
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struct hifn_softc *sc = vsc;
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u_int32_t num1, sts, num2;
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#ifdef __NetBSD__
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u_int32_t num[HIFN_RNG_BITSPER * RND_ENTROPY_THRESHOLD];
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#else
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u_int32_t num[2];
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#endif
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u_int32_t sts;
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int i;
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if (sc->sc_flags & HIFN_IS_7811) {
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for (i = 0; i < 5; i++) {
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for (i = 0; i < 5; i++) { /* XXX why 5? */
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sts = READ_REG_1(sc, HIFN_1_7811_RNGSTS);
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if (sts & HIFN_7811_RNGSTS_UFL) {
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printf("%s: RNG underflow: disabling\n",
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@ -562,22 +586,85 @@ hifn_rng(void *vsc)
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* There are at least two words in the RNG FIFO
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* at this point.
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*/
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num1 = READ_REG_1(sc, HIFN_1_7811_RNGDAT);
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num2 = READ_REG_1(sc, HIFN_1_7811_RNGDAT);
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num[0] = READ_REG_1(sc, HIFN_1_7811_RNGDAT);
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num[1] = READ_REG_1(sc, HIFN_1_7811_RNGDAT);
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if (sc->sc_rngfirst)
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sc->sc_rngfirst = 0;
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else {
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add_true_randomness(num1);
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add_true_randomness(num2);
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}
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#ifdef __NetBSD__
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rnd_add_data(&sc->sc_rnd_source, num,
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2 * sizeof(num[0]),
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(2 * sizeof(num[0]) * NBBY) /
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HIFN_RNG_BITSPER);
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#else
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/*
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* XXX This is a really bad idea.
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* XXX Hifn estimate as little as 0.06
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* XXX actual bits of entropy per output
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* XXX register bit. How can we tell the
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* XXX kernel RNG subsystem we're handing
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* XXX it 64 "true" random bits, for any
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* XXX sane value of "true"?
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* XXX
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* XXX The right thing to do here, if we
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* XXX cannot supply an estimate ourselves,
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* XXX would be to hash the bits locally.
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*/
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add_true_randomness(num[0]);
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add_true_randomness(num[1]);
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#endif
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}
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} else {
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num1 = READ_REG_1(sc, HIFN_1_RNG_DATA);
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#ifdef __NetBSD__
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/* First time through, try to help fill the pool. */
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int nwords = sc->sc_rngfirst ?
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sizeof(num) / sizeof(num[0]) : 4;
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#else
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int nwords = 2;
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#endif
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/*
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* We must be *extremely* careful here. The Hifn
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* 795x differ from the published 6500 RNG design
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* in more ways than the obvious lack of the output
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* FIFO and LFSR control registers. In fact, there
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* is only one LFSR, instead of the 6500's two, and
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* it's 32 bits, not 31.
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*
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* Further, a block diagram obtained from Hifn shows
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* a very curious latching of this register: the LFSR
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* rotates at a frequency of RNG_Clk / 8, but the
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* RNG_Data register is latched at a frequency of
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* RNG_Clk, which means that it is possible for
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* consecutive reads of the RNG_Data register to read
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* identical state from the LFSR. The simplest
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* workaround seems to be to read eight samples from
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* the register for each one that we use. Since each
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* read must require at least one PCI cycle, and
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* RNG_Clk is at least PCI_Clk, this is safe.
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*/
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if (sc->sc_rngfirst)
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if (sc->sc_rngfirst) {
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sc->sc_rngfirst = 0;
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else
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add_true_randomness(num1);
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}
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for(i = 0 ; i < nwords * 8; i++)
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{
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volatile u_int32_t regtmp;
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regtmp = READ_REG_1(sc, HIFN_1_RNG_DATA);
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num[i / 8] = regtmp;
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}
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#ifdef __NetBSD__
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rnd_add_data(&sc->sc_rnd_source, num,
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nwords * sizeof(num[0]),
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(nwords * sizeof(num[0]) * NBBY) /
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HIFN_RNG_BITSPER);
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#else
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/* XXX a bad idea; see 7811 block above */
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add_true_randomness(num[0]);
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#endif
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}
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#ifdef __OpenBSD__
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#else
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callout_reset(&sc->sc_rngto, sc->sc_rnghz, hifn_rng, sc);
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#endif
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#endif /*!__NetBSD__*/
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}
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#endif
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static void
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hifn_puc_wait(struct hifn_softc *sc)
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@ -1,4 +1,4 @@
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/* $NetBSD: hifn7751var.h,v 1.5 2005/02/27 00:27:32 perry Exp $ */
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/* $NetBSD: hifn7751var.h,v 1.6 2005/10/15 08:58:15 tls Exp $ */
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/* $OpenBSD: hifn7751var.h,v 1.18 2000/06/02 22:36:45 deraadt Exp $ */
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/*
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#define HIFN_IS_7956 0x10 /* Hifn 7956/7955 don't have SDRAM */
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#define HIFN_NO_BURSTWRITE 0x20
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#define HIFN_HAS_LEDS 0x40
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#define HIFN_RNG_BITSPER 17 /* From Hifn 6500 paper: 0.06 bits
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of entropy per RNG register bit
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worst-case */
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struct callout sc_rngto; /* rng timeout */
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struct callout sc_tickto; /* led-clear timeout */
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rndsource_element_t sc_rnd_source;
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int sc_rngfirst;
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int sc_rnghz;
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int sc_c_busy; /* command ring busy */
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