Messages in this thread |  | | Date | Wed, 3 Feb 2021 09:16:10 -0800 | From | Ben Widawsky <> | Subject | Re: [PATCH 13/14] cxl/mem: Add limited Get Log command (0401h) |
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On 21-02-02 15:57:03, Dan Williams wrote: > On Tue, Feb 2, 2021 at 3:51 PM Ben Widawsky <ben.widawsky@intel.com> wrote: > > > > On 21-02-01 13:28:48, Konrad Rzeszutek Wilk wrote: > > > On Fri, Jan 29, 2021 at 04:24:37PM -0800, Ben Widawsky wrote: > > > > The Get Log command returns the actual log entries that are advertised > > > > via the Get Supported Logs command (0400h). CXL device logs are selected > > > > by UUID which is part of the CXL spec. Because the driver tries to > > > > sanitize what is sent to hardware, there becomes a need to restrict the > > > > types of logs which can be accessed by userspace. For example, the > > > > vendor specific log might only be consumable by proprietary, or offline > > > > applications, and therefore a good candidate for userspace. > > > > > > > > The current driver infrastructure does allow basic validation for all > > > > commands, but doesn't inspect any of the payload data. Along with Get > > > > Log support comes new infrastructure to add a hook for payload > > > > validation. This infrastructure is used to filter out the CEL UUID, > > > > which the userspace driver doesn't have business knowing, and taints on > > > > invalid UUIDs being sent to hardware. > > > > > > Perhaps a better option is to reject invalid UUIDs? > > > > > > And if you really really want to use invalid UUIDs then: > > > > > > 1) Make that code wrapped in CONFIG_CXL_DEBUG_THIS_IS_GOING_TO..? > > > > > > 2) Wrap it with lockdown code so that you can't do this at all > > > when in LOCKDOWN_INTEGRITY or such? > > > > > > > The commit message needs update btw as CEL is allowed in the latest rev of the > > patches. > > > > We could potentially combine this with the now added (in a branch) CONFIG_RAW > > config option. Indeed I think that makes sense. Dan, thoughts? > > Yeah, unknown UUIDs blocking is the same risk as raw commands as a > vendor can trigger any behavior they want. A "CONFIG_RAW depends on > !CONFIG_INTEGRITY" policy sounds reasonable as well.
What about LOCKDOWN_NONE though? I think we need something runtime for this.
Can we summarize the CONFIG options here?
CXL_MEM_INSECURE_DEBUG // no change CXL_MEM_RAW_COMMANDS // if !security_locked_down(LOCKDOWN_NONE)
bool cxl_unsafe() { #ifndef CXL_MEM_RAW_COMMANDS return false; #else return !security_locked_down(LOCKDOWN_NONE); #endif }
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Did I get that right?
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