On Fri, Oct 27, 2017 at 03:32:26PM -0400, Mimi Zohar wrote: > On Thu, 2017-10-26 at 10:17 -0400, Mimi Zohar wrote: > > On Thu, 2017-10-26 at 15:42 +0800, joeyli wrote: > > > Hi Mimi, > > > > > > Thank you for reviewing. > > > > > > On Mon, Oct 23, 2017 at 11:54:43AM -0400, Mimi Zohar wrote: > > > > On Thu, 2017-10-19 at 15:51 +0100, David Howells wrote: > > > > > From: Chun-Yi Lee <joeyli.kernel@xxxxxxxxx> > > > > > > > > > > When KEXEC_VERIFY_SIG is not enabled, kernel should not loads image > > > > > through kexec_file systemcall if securelevel has been set. > > > > > > > > The patch title and description needs to be updated to refer to > > > > lockdown, not securelevel. > > > > > > > > As previously mentioned the last time these patches were posted, this > > > > leaves out testing to see if the integrity subsystem is enabled. > > > > > > > > Commit 503ceaef8e2e "ima: define a set of appraisal rules requiring > > > > file signatures" was upstreamed. An additional patch could force > > > > these rules to be added to the custom policy, if lockdown is enabled. > > > > This and other patches in this series could then check to see if > > > > is_ima_appraise_enabled() is true. > > > > > > > > Mimi > > > > > > > > > > I have updated the patch title and description, and I also added > > > is_ima_appraise_enabled() as the following. Is it good to you? > > > > Yes, that works. Thanks! Remember is_ima_appraise_enabled() is > > dependent on the "ima: require secure_boot rules in lockdown mode" > > patch - http://kernsec.org/pipermail/linux-security-module-archive/201 > > 7-October/003910.html. > > > > The IMA "secure_boot" policy can be specified on the boot command line > > as ima_policy="secure_boot". It requires kernel modules, firmware, > > kexec kernel image and the IMA custom policy to be signed. In > > lockdown mode, these rules are enabled by default and added to the > > custom policy. > > > > > On the other hand, I am not good on IMA. I have traced the code path > > > in kimage_file_prepare_segments(). Looks that the READING_KEXEC_IMAGE > > > doesn't show in selinux_kernel_read_file(). Where is the exact code > > > in IMA for checking the signature when loading crash kernel file? > > > > kernel_read_file_from_fd() calls the security_kernel_read_file() and > > security_kernel_post_read_file() hooks, which call ima_read_file() and > > ima_post_read_file() respectively. > > Hm, with "lockdown" enabled on the boot command line, I'm now able to > do the kexec load, but not the unload. :/ After the kexec load with I have tried on Qemu with OVMF, I can load and unload second kernel by kexec tool (on openSUSE is in kexec-tools RPM): # kexec -u -s I add -s for using kexec-load-file, and I signed kernel by pesign. > the "--reuse-cmdline" option, the system reboots, but isn't in > "lockdown" mode. > Either enabling secure boot in EFI firmware or using _lockdown_ kernel parameter, the second kernel can be locked down on my OVMF VM. I used following commands: # kexec -s -l /boot/vmlinuz-4.14.0-rc2-default+ --append="$(cat /proc/cmdline)" --initrd=/boot/initrd-4.14.0-rc2-default+ # umount -a; mount -o remount,ro / # kexec -e The kernel source is from David's linux-fs git with lockdown-20171026 tag. The kernel is also signed by pesign. Regards Joey Lee -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
