| Message ID | ZUi5KMUaNkp0c1Ds@gondor.apana.org.au (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | crypto: jitterentropy - Hide esoteric Kconfig options under FIPS and EXPERT | expand |
Am Montag, 6. November 2023, 11:00:08 CET schrieb Herbert Xu: Hi Herbert, > On Thu, Nov 02, 2023 at 08:32:36PM -1000, Linus Torvalds wrote: > > I think that would help the situation, but I assume the sizing for the > > jitter buffer is at least partly due to trying to account for cache > > sizing or similar issues? > > > > Which really means that I assume any static compile-time answer to > > that question is always wrong - whether you are an expert or not. > > Unless you are just building the thing for one particular machine. > > > > So I do think the problem is deeper than "this is a question only for > > experts". I definitely don't think you should ask a regular user (or > > even a distro kernel package manager). I suspect it's likely that the > > question is just wrong in general - because any particular one buffer > > size for any number of machines simply cannot be the right answer. > > > > I realize that the commit says "*allow* for configuration of memory > > size", but I really question the whole approach. > > Yes I think these are all valid points. I just noticed that I > forgot to cc the author so let's see if Stephan has anything to > add. I concur that these questions are more for experts. > > > But yes - hiding these questions from any reasonable normal user is at > > least a good first step. > > OK here's the patch: > > ---8<--- > As JITTERENTROPY is selected by default if you enable the CRYPTO > API, any Kconfig options added there will show up for every single > user. Hide the esoteric options under EXPERT as well as FIPS so > that only distro makers will see them. > > Reported-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> > > diff --git a/crypto/Kconfig b/crypto/Kconfig > index bbf51d55724e..70661f58ee41 100644 > --- a/crypto/Kconfig > +++ b/crypto/Kconfig > @@ -1297,10 +1297,12 @@ config CRYPTO_JITTERENTROPY > > See https://www.chronox.de/jent.html > > +if CRYPTO_JITTERENTROPY > +if CRYPTO_FIPS && EXPERT > + > choice > prompt "CPU Jitter RNG Memory Size" > default CRYPTO_JITTERENTROPY_MEMSIZE_2 > - depends on CRYPTO_JITTERENTROPY > help > The Jitter RNG measures the execution time of memory accesses. > Multiple consecutive memory accesses are performed. If the memory > @@ -1344,7 +1346,6 @@ config CRYPTO_JITTERENTROPY_OSR > int "CPU Jitter RNG Oversampling Rate" > range 1 15 > default 1 > - depends on CRYPTO_JITTERENTROPY > help > The Jitter RNG allows the specification of an oversampling rate (OSR). > The Jitter RNG operation requires a fixed amount of timing > @@ -1359,7 +1360,6 @@ config CRYPTO_JITTERENTROPY_OSR > > config CRYPTO_JITTERENTROPY_TESTINTERFACE > bool "CPU Jitter RNG Test Interface" > - depends on CRYPTO_JITTERENTROPY > help > The test interface allows a privileged process to capture > the raw unconditioned high resolution time stamp noise that > @@ -1377,6 +1377,28 @@ config CRYPTO_JITTERENTROPY_TESTINTERFACE > > If unsure, select N. > > +endif # if CRYPTO_FIPS && EXPERT > + > +if !(CRYPTO_FIPS && EXPERT) > + > +config CRYPTO_JITTERENTROPY_MEMORY_BLOCKS > + int > + default 64 > + > +config CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE > + int > + default 32 > + > +config CRYPTO_JITTERENTROPY_OSR > + int > + default 1 > + > +config CRYPTO_JITTERENTROPY_TESTINTERFACE > + bool > + > +endif # if !(CRYPTO_FIPS && EXPERT) > +endif # if CRYPTO_JITTERENTROPY > + > config CRYPTO_KDF800108_CTR > tristate > select CRYPTO_HMAC Reviewed-by: Stephan Mueller <smueller@chronox.de> Ciao Stephan
Hi Herbert, Yamada-san, On Mon, Nov 6, 2023 at 11:00 AM Herbert Xu <herbert@gondor.apana.org.au> wrote: > On Thu, Nov 02, 2023 at 08:32:36PM -1000, Linus Torvalds wrote: > > I think that would help the situation, but I assume the sizing for the > > jitter buffer is at least partly due to trying to account for cache > > sizing or similar issues? > > > > Which really means that I assume any static compile-time answer to > > that question is always wrong - whether you are an expert or not. > > Unless you are just building the thing for one particular machine. > > > > So I do think the problem is deeper than "this is a question only for > > experts". I definitely don't think you should ask a regular user (or > > even a distro kernel package manager). I suspect it's likely that the > > question is just wrong in general - because any particular one buffer > > size for any number of machines simply cannot be the right answer. > > > > I realize that the commit says "*allow* for configuration of memory > > size", but I really question the whole approach. > > Yes I think these are all valid points. I just noticed that I > forgot to cc the author so let's see if Stephan has anything to > add. > > > But yes - hiding these questions from any reasonable normal user is at > > least a good first step. > > OK here's the patch: > > ---8<--- > As JITTERENTROPY is selected by default if you enable the CRYPTO > API, any Kconfig options added there will show up for every single > user. Hide the esoteric options under EXPERT as well as FIPS so > that only distro makers will see them. > > Reported-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Thanks for your patch, which is now commit e7ed6473c2c8c4e4 ("crypto: jitterentropy - Hide esoteric Kconfig options under FIPS and EXPERT"). > --- a/crypto/Kconfig > +++ b/crypto/Kconfig > @@ -1297,10 +1297,12 @@ config CRYPTO_JITTERENTROPY > > See https://www.chronox.de/jent.html > > +if CRYPTO_JITTERENTROPY > +if CRYPTO_FIPS && EXPERT > + > choice > prompt "CPU Jitter RNG Memory Size" > default CRYPTO_JITTERENTROPY_MEMSIZE_2 > - depends on CRYPTO_JITTERENTROPY > help > The Jitter RNG measures the execution time of memory accesses. > Multiple consecutive memory accesses are performed. If the memory > @@ -1344,7 +1346,6 @@ config CRYPTO_JITTERENTROPY_OSR > int "CPU Jitter RNG Oversampling Rate" > range 1 15 > default 1 > - depends on CRYPTO_JITTERENTROPY > help > The Jitter RNG allows the specification of an oversampling rate (OSR). > The Jitter RNG operation requires a fixed amount of timing > @@ -1359,7 +1360,6 @@ config CRYPTO_JITTERENTROPY_OSR > > config CRYPTO_JITTERENTROPY_TESTINTERFACE > bool "CPU Jitter RNG Test Interface" > - depends on CRYPTO_JITTERENTROPY > help > The test interface allows a privileged process to capture > the raw unconditioned high resolution time stamp noise that > @@ -1377,6 +1377,28 @@ config CRYPTO_JITTERENTROPY_TESTINTERFACE > > If unsure, select N. > > +endif # if CRYPTO_FIPS && EXPERT > + > +if !(CRYPTO_FIPS && EXPERT) > + > +config CRYPTO_JITTERENTROPY_MEMORY_BLOCKS > + int > + default 64 > + > +config CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE > + int > + default 32 > + > +config CRYPTO_JITTERENTROPY_OSR > + int > + default 1 > + > +config CRYPTO_JITTERENTROPY_TESTINTERFACE > + bool This duplicates the symbols in the CRYPTO_FIPS && EXPERT section above, which is fragile. For the int and bool symbols, this can be handled without duplication using: config CRYPTO_JITTERENTROPY_OSR - int "CPU Jitter RNG Oversampling Rate" + int "CPU Jitter RNG Oversampling Rate" if CRYPTO_FIPS && EXPERT config CRYPTO_JITTERENTROPY_TESTINTERFACE - bool "CPU Jitter RNG Test Interface" + bool "CPU Jitter RNG Test Interface" if CRYPTO_FIPS && EXPERT Unfortunately the following does not work for the choice statement, although kconfig does not report an error: choice - prompt "CPU Jitter RNG Memory Size" + prompt "CPU Jitter RNG Memory Size" if CRYPTO_FIPS && EXPERT default CRYPTO_JITTERENTROPY_MEMSIZE_2 Unlike for other symbol types, which just become silent if !(CRYPTO_FIPS && EXPERT), the choice is skipped completely if !(CRYPTO_FIPS && EXPERT), and CRYPTO_JITTERENTROPY_MEMSIZE_2 is not set. Yamada-san: Do you know why choice behaves differently? Is this easy to fix? Thanks! > + > +endif # if !(CRYPTO_FIPS && EXPERT) > +endif # if CRYPTO_JITTERENTROPY > + > config CRYPTO_KDF800108_CTR > tristate > select CRYPTO_HMAC Gr{oetje,eeting}s, Geert
diff --git a/crypto/Kconfig b/crypto/Kconfig index bbf51d55724e..70661f58ee41 100644 --- a/crypto/Kconfig +++ b/crypto/Kconfig @@ -1297,10 +1297,12 @@ config CRYPTO_JITTERENTROPY See https://www.chronox.de/jent.html +if CRYPTO_JITTERENTROPY +if CRYPTO_FIPS && EXPERT + choice prompt "CPU Jitter RNG Memory Size" default CRYPTO_JITTERENTROPY_MEMSIZE_2 - depends on CRYPTO_JITTERENTROPY help The Jitter RNG measures the execution time of memory accesses. Multiple consecutive memory accesses are performed. If the memory @@ -1344,7 +1346,6 @@ config CRYPTO_JITTERENTROPY_OSR int "CPU Jitter RNG Oversampling Rate" range 1 15 default 1 - depends on CRYPTO_JITTERENTROPY help The Jitter RNG allows the specification of an oversampling rate (OSR). The Jitter RNG operation requires a fixed amount of timing @@ -1359,7 +1360,6 @@ config CRYPTO_JITTERENTROPY_OSR config CRYPTO_JITTERENTROPY_TESTINTERFACE bool "CPU Jitter RNG Test Interface" - depends on CRYPTO_JITTERENTROPY help The test interface allows a privileged process to capture the raw unconditioned high resolution time stamp noise that @@ -1377,6 +1377,28 @@ config CRYPTO_JITTERENTROPY_TESTINTERFACE If unsure, select N. +endif # if CRYPTO_FIPS && EXPERT + +if !(CRYPTO_FIPS && EXPERT) + +config CRYPTO_JITTERENTROPY_MEMORY_BLOCKS + int + default 64 + +config CRYPTO_JITTERENTROPY_MEMORY_BLOCKSIZE + int + default 32 + +config CRYPTO_JITTERENTROPY_OSR + int + default 1 + +config CRYPTO_JITTERENTROPY_TESTINTERFACE + bool + +endif # if !(CRYPTO_FIPS && EXPERT) +endif # if CRYPTO_JITTERENTROPY + config CRYPTO_KDF800108_CTR tristate select CRYPTO_HMAC