於 二，2013-08-27 於 13:30 +0200，Pavel Machek 提到： > On Tue 2013-08-27 18:22:17, joeyli wrote: > > 於 日，2013-08-25 於 18:43 +0200，Pavel Machek 提到： > > > On Thu 2013-08-22 19:01:56, Lee, Chun-Yi wrote: > > > > This patch introduced SNAPSHOT_SIG_HASH config for user to select which > > > > hash algorithm will be used during signature generation of snapshot. > > > > > > > > v2: > > > > Add define check of oCONFIG_SNAPSHOT_VERIFICATION in snapshot.c before > > > > declare pkey_hash(). > > > > > > > > Reviewed-by: Jiri Kosina <jkos...@suse.cz> > > > > Signed-off-by: Lee, Chun-Yi <j...@suse.com> > > > > --- > > > > kernel/power/Kconfig | 46 > > > > ++++++++++++++++++++++++++++++++++++++++++++++ > > > > kernel/power/snapshot.c | 27 ++++++++++++++++++++++----- > > > > 2 files changed, 68 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig > > > > index b592d88..79b34fa 100644 > > > > --- a/kernel/power/Kconfig > > > > +++ b/kernel/power/Kconfig > > > > @@ -78,6 +78,52 @@ config SNAPSHOT_VERIFICATION > > > > dependent on UEFI environment. EFI bootloader should generate > > > > the > > > > key-pair. > > > > > > > > +choice > > > > + prompt "Which hash algorithm should snapshot be signed with?" > > > > + depends on SNAPSHOT_VERIFICATION > > > > + help > > > > + This determines which sort of hashing algorithm will be used > > > > during > > > > + signature generation of snapshot. This algorithm _must_ be > > > > built into > > > > + the kernel directly so that signature verification can take > > > > place. > > > > + It is not possible to load a signed snapshot containing the > > > > algorithm > > > > + to check the signature on that module. > > > > > > Like if 1000 ifdefs you already added to the code are not enough, you > > > make some new ones? > > > Pavel > > > > > > > This SNAPSHOT_SIG_HASH kernel config is to select which SHA algorithms > > used for generate digest of snapshot. The configuration will captured by > > a const char* in code: > > > > +static const char *snapshot_hash = CONFIG_SNAPSHOT_SIG_HASH; > > + > > +static int pkey_hash(void) > > > > So, there doesn't have any ifdef block derived from this new config. > > I'd say select one hash function, and use it. There's no need to make > it configurable. > Pavel
There have better performance when SHA algorithm output shorter hash result. On the other hand, longer hash result provide better security. And, on 64-bits system, the SHA512 has better performance then SHA256. Due to user have different use case and different hardware, why not give them this option to make decision? Thanks a lot! Joey LEe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
