From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from cavan.codon.org.uk ([2a00:1098:0:80:1000:c:0:1]) by casper.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TQgbx-00039s-MZ for kexec@lists.infradead.org; Tue, 23 Oct 2012 15:41:47 +0000 Date: Tue, 23 Oct 2012 16:41:24 +0100 From: Matthew Garrett Subject: Re: [RFC] Kdump with UEFI secure boot (Re: [PATCH v2] kdump: pass acpi_rsdp= to 2nd kernel for efi booting) Message-ID: <20121023154123.GA30730@srcf.ucam.org> References: <20121018191107.GC18147@redhat.com> <1350588121.30243.7.camel@rhapsody> <20121018193831.GD18147@redhat.com> <874nlrv2ni.fsf@xmission.com> <20121019020630.GA27052@redhat.com> <877gqnnnf0.fsf@xmission.com> <20121019143112.GB27052@redhat.com> <871ugqb4gj.fsf@xmission.com> <20121023131854.GA16496@redhat.com> <20121023145920.GD16496@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20121023145920.GD16496@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Vivek Goyal Cc: kexec@lists.infradead.org, horms@verge.net.au, "Eric W. Biederman" , "H. Peter Anvin" , Dave Young , Khalid Aziz On Tue, Oct 23, 2012 at 10:59:20AM -0400, Vivek Goyal wrote: > But what about creation of a new program which can call kexec_load() > and execute an unsigned kernel. Doesn't look like that will be > prevented using IMA. Right. Trusting userspace would require a new system call that passes in a signature of the userspace binary, and the kernel would then have to verify the ELF object in memory in order to ensure that it matches the signature. Verifying that the copy on the filesystem is unmodified isn't adequate - an attacker could simply have paused the process and injected code. Realistically, the only solution here is for the kernel to verify that the kernel it's about to boot is signed and for it not to take any untrusted executable code from userspace. -- Matthew Garrett | mjg59@srcf.ucam.org _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec