Hi, I do not think the list of erased symbols must be secret. After all we use a special value to do most of the erasing. Thus hinting at what was erased. The intention of this item is certainly not to unduly confuse service. this work shall increase the customers confidence that no sensitive data may leak through a dump - clearly at the cost with very low probability some problems may no longer be analyzed. - But that's all you can do if sensitive data is really needed to analyze a problem. Mit freundlichen Gr??en/Best Regards/Cordialement Reinhard Dr. Reinhard B?ndgen RAS & Crypto Architect for Linux on System z Virtualization and Systems Management Mail:buendgen at de.ibm.com Phone: ++49-(0)7031-16-1130 Fax: ++49-(0)7031-16-3456 IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter Gesch?ftsf?hrung: Dirk Wittkopp Sitz der Gesellschaft: B?blingen Registergericht: Amtsgericht Stuttgart, HRB 243294 From: "Ken'ichi Ohmichi" <oomichi@xxxxxxxxxxxxxxxxx> To: Mahesh Jagannath Salgaonkar <mahesh at linux.vnet.ibm.com> Cc: Dave Anderson <anderson at redhat.com>, V Srivatsa <vsrivatsa at in.ibm.com>, kexec at lists.infradead.org, Ananth N Mavinakayanahalli <ananth at in.ibm.com>, Reinhard Buendgen/Germany/IBM at IBMDE Date: 14.03.2011 08:08 Subject: Re: [PATCH v1 0/6] makedumpfile: makedumpfile enhancement to filter out kernel data from vmcore Hi Mahesh, On Mon, 14 Mar 2011 11:48:19 +0530 Mahesh Jagannath Salgaonkar <mahesh at linux.vnet.ibm.com> wrote: > > > > > > ----- Original Message ----- > >> Hi All, > >> > >> Please find the makedumpfile enhancement patchset that introduces a data > >> filtering feature which enables makedumpfile to filter out desired kernel > >> symbol data and it's members from the specified VMCORE file. The data to be > >> filtered out is poisoned with character 'X' (58 in Hex). > >> > >> This feature will be very useful for the customers who wants to erase the > >> customer sensitive data like security keys and other confidential data, in > >> DUMPFILE before sending it to support team for analysis. > >> > >> This feature introduces a filter config file where, using filter commands, > >> user can specify desired kernel data symbols and it's members that need to be > >> filtered out while creating o/p DUMPFILE. The Syntax for filter commands are > >> provided in the filter.conf(8) man page. > >> > >> The first 4 patches prepares the base work for filtering framework. The last 2 > >> patches implements the generic filtering framework to erase desired kernel > >> data. > >> > >> I have tested these patches on x86_64 and s390x architecture against RHEL6 GA > >> kernel. The feature supports filtering data from ELF as well as kdump-compressed > >> formatted dump. > >> > >> Please review the patchset and let me know your comments. > >> > >> Thanks, > >> -Mahesh. > > > > Hi Mahesh, > > > > Is there any notation in the filtered ELF kdump or compressed kdump file > > that filtering has been done? Given that there may be potential ramifications > > in crash utility behavior (or outright failure?), the crash utility should > > display a warning message early on during invocation. > > Hmm... I did not think about it. I am thinking of following approach: > > - Set a bit in dump_level (DL_FILTER_KERNEL_DATA => 0x800) that will > denote that filtering has been done. > - For compressed kdump file we anyway have dump_level available in kdump > sub header > - For ELF kdump, currently we do not have any way to convey dump_level > info to crash utility (Ken'chi, correct me if I am wrong). How about > introducing an additional ELF note (NT_DUMP_LEVEL) that will include > dump_level info. On your above approach, a member of support team for analysis cannot know what symbols are erased. And he/she will not believe the received dumpfile from a customer site. I have one question, do you think it is better not to inform support team of the erased symbols ? Is also the list of the erased symbols secret ? Thanks Ken'ichi Ohmichi -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.infradead.org/pipermail/kexec/attachments/20110314/1c4d8a88/attachment-0001.html>
