Re: [PATCH 1/3] sha512: make it work, undo percpu message schedule
On Sat, Jan 14, 2012 at 09:27:37PM +0300, Alexey Dobriyan wrote: > commit f9e2bca6c22d75a289a349f869701214d63b5060 > aka "crypto: sha512 - Move message schedule W[80] to static percpu area" > created global message schedule area. > > If sha512_update will ever be entered twice, hash will be silently > calculated incorrectly. > > Probably the easiest way to notice incorrect hashes being calculated is > to run 2 ping floods over AH with hmac(sha512): > > #!/usr/sbin/setkey -f > flush; > spdflush; > add IP1 IP2 ah 25 -A hmac-sha512 > 0x0025; > add IP2 IP1 ah 52 -A hmac-sha512 > 0x0052; > spdadd IP1 IP2 any -P out ipsec ah/transport//require; > spdadd IP2 IP1 any -P in ipsec ah/transport//require; > > XfrmInStateProtoError will start ticking with -EBADMSG being returned > from ah_input(). This never happens with, say, hmac(sha1). > > With patch applied (on BOTH sides), XfrmInStateProtoError does not tick > with multiple bidirectional ping flood streams like it doesn't tick > with SHA-1. > > After this patch sha512_transform() will start using ~750 bytes of stack on > x86_64. > This is OK for simple loads, for something more heavy, stack reduction will > be done > separatedly. > > Signed-off-by: Alexey Dobriyan > Cc: sta...@vger.kernel.org OK, I've applied patches 1-2 to crypto and patch 3 to cryptodev. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/3] sha512: make it work, undo percpu message schedule
Le samedi 14 janvier 2012 à 13:52 -0800, Linus Torvalds a écrit : > On Sat, Jan 14, 2012 at 1:46 PM, Eric Dumazet wrote: > > > > This is too risky, and we provided an alternate patch, not just for fun. > > Did you see the second patch? > I saw it and felt it was not a stable material. And Herbert sent an alternate patch, then I sent a V3 patch. > The one that got rid of the *stupid* 80-entry array? > Maybe, I didnt wrote this code, and I am very glad this code can be smarter and all. -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/3] sha512: make it work, undo percpu message schedule
On Sat, Jan 14, 2012 at 1:46 PM, Eric Dumazet wrote: > > This is too risky, and we provided an alternate patch, not just for fun. Did you see the second patch? The one that got rid of the *stupid* 80-entry array? I don't know why so many sha implementations do that idiotic full array, when the circular one is much better. In fact, the 16-entry circular array allows machines with lots of registers to keep all the state in registers and the C implementation can often be as good as hand-tuned assembly. At least that's true for sha1, I'm not sure you can do the same with sha512. But that actually *requires* that the 16-entry array be done on the stack as an automatic array. Anything else, and the compiler won't be able to do it. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/3] sha512: make it work, undo percpu message schedule
Le samedi 14 janvier 2012 à 21:27 +0300, Alexey Dobriyan a écrit :
> commit f9e2bca6c22d75a289a349f869701214d63b5060
> aka "crypto: sha512 - Move message schedule W[80] to static percpu area"
> created global message schedule area.
> Signed-off-by: Alexey Dobriyan
> Cc: sta...@vger.kernel.org
> ---
>
> crypto/sha512_generic.c |6 +-
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> --- a/crypto/sha512_generic.c
> +++ b/crypto/sha512_generic.c
> @@ -21,8 +21,6 @@
> #include
> #include
>
> -static DEFINE_PER_CPU(u64[80], msg_schedule);
> -
> static inline u64 Ch(u64 x, u64 y, u64 z)
> {
> return z ^ (x & (y ^ z));
> @@ -89,7 +87,7 @@ sha512_transform(u64 *state, const u8 *input)
> u64 a, b, c, d, e, f, g, h, t1, t2;
>
> int i;
> - u64 *W = get_cpu_var(msg_schedule);
> + u64 W[80];
>
> /* load the input */
> for (i = 0; i < 16; i++)
> @@ -128,8 +126,6 @@ sha512_transform(u64 *state, const u8 *input)
>
> /* erase our data */
> a = b = c = d = e = f = g = h = t1 = t2 = 0;
> - memset(W, 0, sizeof(__get_cpu_var(msg_schedule)));
> - put_cpu_var(msg_schedule);
> }
>
> static int
Is it just me or are you ignoring what crypto maintainer and others
thought of your patch ?
You are re-introducing a 640 bytes stack array, how comes it can be
really safe ?
This is too risky, and we provided an alternate patch, not just for fun.
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