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Message-ID: <20190115024243.GA9199@dhcp-128-65.nay.redhat.com> Date: Tue, 15 Jan 2019 10:42:43 +0800 From: Dave Young <dyoung@...hat.com> To: Mimi Zohar <zohar@...ux.ibm.com> Cc: Kairui Song <kasong@...hat.com>, linux-kernel@...r.kernel.org, dhowells@...hat.com, dwmw2@...radead.org, jwboyer@...oraproject.org, keyrings@...r.kernel.org, jmorris@...ei.org, serge@...lyn.com, bauerman@...ux.ibm.com, ebiggers@...gle.com, nayna@...ux.ibm.com, linux-integrity@...r.kernel.org, kexec@...ts.infradead.org Subject: Re: [RFC PATCH 2/2] kexec, KEYS: Make use of platform keyring for signature verify On 01/14/19 at 11:10am, Mimi Zohar wrote: > On Sun, 2019-01-13 at 09:39 +0800, Dave Young wrote: > > Hi, > > > > On 01/11/19 at 11:13am, Mimi Zohar wrote: > > > On Fri, 2019-01-11 at 21:43 +0800, Dave Young wrote: > > > [snip] > > > > > > > Personally I would like to see platform key separated from integrity. > > > > But for the kexec_file part I think it is good at least it works with > > > > this fix. > > > > > > > > Acked-by: Dave Young <dyoung@...hat.com> > > > > > > The original "platform" keyring patches that Nayna posted multiple > > > times were in the certs directory, but nobody commented/responded. So > > > she reworked the patches, moving them to the integrity directory and > > > posted them (cc'ing the kexec mailing list). It's a bit late to be > > > asking to move it, isn't it? > > > > Hmm, apologize for being late, I did not get chance to have a look the > > old series. Since we have the needs now, it should be still fine > > > > Maybe Kairui can check Nayna's old series, see if he can do something > > again? > > Whether the platform keyring is defined in certs/ or in integrity/ the > keyring id needs to be accessible to the other, without making the > keyring id global. Moving where the platform keyring is defined is > not the problem. Agreed, but just feel kexec depends on IMA sounds not good. > > Commit a210fd32a46b ("kexec: add call to LSM hook in original > kexec_load syscall") introduced a new LSM hook. Assuming > CONFIG_KEXEC_VERIFY_SIG is enabled, with commit b5ca117365d9 ("ima: > prevent kexec_load syscall based on runtime secureboot flag") we can > now block the kexec_load syscall. Without being able to block the > kexec_load syscall, verifying the kexec image signature via the > kexec_file_load syscall is kind of pointless. > > Unless you're planning on writing an LSM to prevent the kexec_load > syscall, I assume you'll want to enable integrity anyway. User can disable kexec_load in kernel config, and only allow kexec_file_load. But yes, this can be improved separately in case no IMA enabled. For the time being we can leave with it and fix like this series do. > > Mimi > Thanks Dave
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