Trying to kexec with the sysctl enabled correctly gives "kexec_load failed: Operation not permitted". Re-enabling it does not work, as expected. With the sysctl untouched kexec works just fine.
** Tags removed: verification-needed-saucy ** Tags added: verification-done-saucy -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1259570 Title: kexec should get a disabling sysctl Status in “linux” package in Ubuntu: Fix Released Status in “linux-lts-saucy” package in Ubuntu: Invalid Status in “linux” source package in Precise: Won't Fix Status in “linux-lts-saucy” source package in Precise: Fix Committed Status in “linux” source package in Quantal: Won't Fix Status in “linux-lts-saucy” source package in Quantal: Invalid Status in “linux” source package in Raring: Invalid Status in “linux-lts-saucy” source package in Raring: Invalid Status in “linux” source package in Saucy: Fix Committed Status in “linux-lts-saucy” source package in Saucy: Invalid Status in “linux” source package in Trusty: Fix Released Status in “linux-lts-saucy” source package in Trusty: Invalid Bug description: To enable kexec makes sense for a generic distro kernel. But if your users have root in their virtual machines, and you want to make it hard for them to run code in ring 0, you commonly disable further module loading and you also want to disable kexec[1]. Kees Cook wrote up a patch[2] that we'd like to see applied to the Ubuntu kernel to avoid recompilation of the distro kernel. I'm marking this as a security issue on the ground that it's quite surprising that setting kernel.modules_disabled=1 as a hardening feature can be subverted by using kexec. [1] http://mjg59.dreamwidth.org/28746.html [2] https://lkml.org/lkml/2013/12/9/765 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1259570/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
