Huh, I've never seen that before... thanks, I'm gonna give it a try and report back!
On Tue, May 10, 2022 at 4:44 PM Dimitri John Ledkov < dimitri.led...@canonical.com> wrote: > On Tue, 10 May 2022 at 15:07, Łukasz Piątkowski <pion...@gmail.com> wrote: > > > > What I'm trying to do is to sign a mainline kernel built by ubuntu ( > https://kernel.ubuntu.com/~kernel-ppa/mainline/) with my private key, > that is already enrolled to MOK, and boot it with Secure Boot. > > > > > the MOK key as generated by Ubuntu/Debian tooling, creates a signing > certificate that self-limits itself to only support Kernel Module signing. > > > > OK, that explains why the key in `/var/lib/shim-signed/mok` doesn't > work. Still, I have created my own key as well (listed below for > inspection, it has code signing extension), enrolled that key in MOK and > signed the ubuntu mainline kernel (the kernel I'm trying to boot) with it. > The result is exactly the same. I was using exactly the same procedure a > few ubuntu editions back and it was definitely working. From what I learned > so far, this might be related to the BootHole bug ( > https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10713) that was > fixed some time ago. > > > > My generated key is: > > > > root@T495:~/mok# openssl x509 -in MOK.pem -text -noout > > Certificate: > > Data: > > Version: 3 (0x2) > > Serial Number: > > 42:61:86:b2:29:3d:ca:eb:98:87:ae:3d:74:95:c7:f2:63:8f:8a:3b > > Signature Algorithm: sha256WithRSAEncryption > > Issuer: C = PL, ST = Poznan, L = Poznan, O = none, CN = Secure > Boot Signing, emailAddress = exam...@example.com > > Validity > > Not Before: Feb 18 19:28:16 2020 GMT > > Not After : Jan 25 19:28:16 2120 GMT > > Subject: C = PL, ST = Poznan, L = Poznan, O = none, CN = Secure > Boot Signing, emailAddress = exam...@example.com > > Subject Public Key Info: > > Public Key Algorithm: rsaEncryption > > Public-Key: (2048 bit) > > Modulus: [cut] > > Exponent: 65537 (0x10001) > > X509v3 extensions: > > X509v3 Subject Key Identifier: > > > EC:57:4E:BD:DC:1A:CF:B4:55:16:4A:CE:CB:E4:9E:44:5C:C4:63:F6 > > X509v3 Authority Key Identifier: > > > EC:57:4E:BD:DC:1A:CF:B4:55:16:4A:CE:CB:E4:9E:44:5C:C4:63:F6 > > X509v3 Basic Constraints: critical > > CA:FALSE > > X509v3 Extended Key Usage: > > Code Signing, 1.3.6.1.4.1.311.10.3.6, > 1.3.6.1.4.1.2312.16.1.2 > > This is bad... certs that have 1.3.6.1.4.1.2312.16.1.2 cannot be used > to sign kernels. > > Your cert must _not_ have 1.3.6.1.4.1.2312.16.1.2 EKU set on it. > > You cannot use the same certificate to sign both kernel and modules. > > > Netscape Comment: > > OpenSSL Generated Certificate > > Signature Algorithm: sha256WithRSAEncryption > > Signature Value: [cut] > > > > On Tue, May 10, 2022 at 3:26 PM Dimitri John Ledkov < > dimitri.led...@canonical.com> wrote: > >> > >> the MOK key as generated by Ubuntu/Debian tooling, creates a signing > >> certificate that self-limits itself to only support Kernel Module > >> signing. > >> Signatures made by such certificate, are not trusted by shim for the > >> purpose of code signing of bootloaders (i.e. grub) or kernels (i.e. > >> linux). > >> I also responded this on stackoverflow. > >> > >> The automatically generated MOK key is only usable to sign kernel > >> modules, i.e. self-built DKMS modules. > >> > >> -- > >> okurrr, > >> > >> Dimitri > >> > >> On Tue, 10 May 2022 at 11:33, Łukasz Piątkowski <pion...@gmail.com> > wrote: > >> > > >> > Hi everyone - I'm new here! > >> > > >> > Sorry for going with my problem directly to the grub-devel maling > list, but I'm pretty sure my problem is GRUB related. Still, I've spent > some hours trying to find a solution on the Internet and I failed :( So, > here it comes - if anyone has time to explain my problem to a layman, it > would be awesome. Even better, if you can maybe answer here on > stackoverflow, where it can be easier to find, I believe ( > https://unix.stackexchange.com/questions/701612/cant-load-self-signed-kernel-with-secure-boot-on-bad-shim-signature > ). > >> > > >> > I'm running ubuntu with Secure Boot on. Everything works fine when I > use a kernel that comes packaged from cannonical. Still, I have issues > running a self-signed kernel (this is actually an externally built kernel, > that I have verified and want to use for my own machine). I'm pretty sure > my signature with MOK key is OK (verification below), but still when I try > to boot the kernel from grub, after selecting the correct entry, I get an > error that reads "Loading ... error: bad shim signature." I'm wrapping my > head around it and can't find a solution. Why, even though both kernels are > signed with MOK keys, one of them works and the other doesn't? > >> > > >> > Here's info about kernel signatures: > >> > > >> > root@T495:~# sbsign --key /var/lib/shim-signed/mok/MOK.priv --cert > /var/lib/shim-signed/mok/MOK.pem /boot/vmlinuz > >> > Image was already signed; adding additional signature > >> > > >> > root@T495:~# sbverify --list /boot/vmlinuz > >> > signature 1 > >> > image signature issuers: > >> > - /C=PL/ST=Poznan/L=Poznan/O=none/CN=Secure Boot > Signing/emailAddress=exam...@example.com > >> > image signature certificates: > >> > - subject: /C=PL/ST=yes/L=yes/O=none/CN=Secure Boot > Signing/emailAddress=exam...@example.com > >> > issuer: /C=PL/ST=yes/L=yes/O=none/CN=Secure Boot > Signing/emailAddress=exam...@example.com > >> > signature 2 > >> > image signature issuers: > >> > - /CN=ubuntu Secure Boot Module Signature key > >> > image signature certificates: > >> > - subject: /CN=ubuntu Secure Boot Module Signature key > >> > issuer: /CN=ubuntu Secure Boot Module Signature key > >> > > >> > > >> > And here about MOK keys: > >> > > >> > root@T495:~# openssl x509 -in /var/lib/shim-signed/mok/MOK.pem > -fingerprint -noout > >> > SHA1 > Fingerprint=81:A2:93:CB:06:6F:52:BA:D9:E2:39:68:9D:FA:E2:2B:0C:95:3C:F7 > >> > root@T495:~# mokutil --list-enrolled | grep "81:a2:93" > >> > SHA1 Fingerprint: > 81:a2:93:cb:06:6f:52:ba:d9:e2:39:68:9d:fa:e2:2b:0c:95:3c:f7 > >> > > >> > If there are any docs that help understand that, I'm happy to be > redirected there :) > >> > > >> > piontec > >> > _______________________________________________ > >> > Grub-devel mailing list > >> > Grub-devel@gnu.org > >> > https://lists.gnu.org/mailman/listinfo/grub-devel > >> > >> _______________________________________________ > >> Grub-devel mailing list > >> Grub-devel@gnu.org > >> https://lists.gnu.org/mailman/listinfo/grub-devel > > > > _______________________________________________ > > Grub-devel mailing list > > Grub-devel@gnu.org > > https://lists.gnu.org/mailman/listinfo/grub-devel > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel >
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