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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id a3sm7377415pfo.49.2019.06.22.16.53.20 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 22 Jun 2019 16:53:20 -0700 (PDT) Date: Sat, 22 Jun 2019 16:53:19 -0700 From: Kees Cook To: Matthew Garrett Cc: jmorris@namei.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Dave Young , David Howells , Matthew Garrett , kexec@lists.infradead.org Subject: Re: [PATCH V34 07/29] Copy secure_boot flag in boot params across kexec reboot Message-ID: <201906221653.DDCB3C898@keescook> References: <20190622000358.19895-1-matthewgarrett@google.com> <20190622000358.19895-8-matthewgarrett@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190622000358.19895-8-matthewgarrett@google.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Fri, Jun 21, 2019 at 05:03:36PM -0700, Matthew Garrett wrote: > From: Dave Young > > Kexec reboot in case secure boot being enabled does not keep the secure > boot mode in new kernel, so later one can load unsigned kernel via legacy > kexec_load. In this state, the system is missing the protections provided > by secure boot. > > Adding a patch to fix this by retain the secure_boot flag in original > kernel. > > secure_boot flag in boot_params is set in EFI stub, but kexec bypasses the > stub. Fixing this issue by copying secure_boot flag across kexec reboot. > > Signed-off-by: Dave Young Reviewed-by: Kees Cook -Kees > Signed-off-by: David Howells > Signed-off-by: Matthew Garrett > cc: kexec@lists.infradead.org > --- > arch/x86/kernel/kexec-bzimage64.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c > index 22f60dd26460..4243359ac509 100644 > --- a/arch/x86/kernel/kexec-bzimage64.c > +++ b/arch/x86/kernel/kexec-bzimage64.c > @@ -182,6 +182,7 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr, > if (efi_enabled(EFI_OLD_MEMMAP)) > return 0; > > + params->secure_boot = boot_params.secure_boot; > ei->efi_loader_signature = current_ei->efi_loader_signature; > ei->efi_systab = current_ei->efi_systab; > ei->efi_systab_hi = current_ei->efi_systab_hi; > -- > 2.22.0.410.gd8fdbe21b5-goog > -- Kees Cook