b261a30c90
This is used to package up the grub bootloader into a firmware volume where it can be executed as a shell like the UEFI Shell. Grub itself is built as a minimal entity into a Fv and then added as a boot option. By default the UEFI shell isn't built but for debugging purposes it can be enabled and will then be presented as a boot option (This should never be allowed for secure boot in an external data centre but may be useful for local debugging). Finally all other boot options except grub and possibly the shell are stripped and the boot timeout forced to 0 so the system will not enter a setup menu and will only boot to grub. This is done by copying the Library/PlatformBootManagerLib into Library/PlatformBootManagerLibGrub and then customizing it. Boot failure is fatal to try to prevent secret theft. Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3077 Signed-off-by: James Bottomley <jejb@linux.ibm.com> Message-Id: <20201130202819.3910-4-jejb@linux.ibm.com> Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com> [lersek@redhat.com: replace local variable initialization with assignment] Reviewed-by: Laszlo Ersek <lersek@redhat.com> [lersek@redhat.com: squash 'OvmfPkg: add "gGrubFileGuid=Grub" to GuidCheck.IgnoreDuplicates', reviewed stand-alone by Phil (msgid <e6eae551-8563-ccfb-5547-7a97da6d46e5@redhat.com>) and Ard (msgid <10aeda37-def6-d9a4-6e02-4c66c1492f57@arm.com>)]
47 lines
1.1 KiB
INI
47 lines
1.1 KiB
INI
## @file
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# Execute a script to recover the SEV supplied secret and use it to
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# decrypt a luks volume. For security, the kernel must be on an encrypted
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# volume so reboot if none are found.
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#
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# Copyright (C) 2020 James Bottomley, IBM Corporation.
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#
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# SPDX-License-Identifier: BSD-2-Clause-Patent
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#
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##
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echo "Entering grub config"
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sevsecret
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if [ $? -ne 0 ]; then
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echo "Failed to locate anything in the SEV secret area, prompting for password"
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cryptomount -a
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else
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cryptomount -s
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if [ $? -ne 0 ]; then
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echo "Failed to mount root securely, retrying with password prompt"
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cryptomount -a
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fi
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fi
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set root=
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for f in (crypto*); do
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if [ -e $f/boot/grub/grub.cfg ]; then
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set root=$f
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set prefix=($root)/boot/grub
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break;
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fi
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done
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if [ x$root = x ]; then
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echo "Failed to find any grub configuration on the encrypted volume"
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sleep 5
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reboot
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fi
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# rest of modules to get boot to work
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set modules="
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boot
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loadenv
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"
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for f in $modules; do
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insmod $f
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done
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echo "Transferring to ${prefix}/grub.cfg"
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source $prefix/grub.cfg
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