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authorLeah Rowe <leah@libreboot.org>2024-06-22 22:57:39 +0100
committerLeah Rowe <leah@libreboot.org>2024-06-22 22:57:39 +0100
commite67cd17164fd1934cd908b1f281867fac1cd73ae (patch)
treeb8f4a1677062c0a4cac3de45e12f5d28449da32c /script
parent71137b12b497e6935c81bf5fc73a0c17246fafd2 (diff)
roms: only support SeaBIOS/SeaGRUB on x86
Never, ever build images where GRUB is the primary payload. These options have been removed from target.cfg handling: * seabios_withgrub * grub_withseabios The "payload_grub" variable now does the same thing as the old "seabios_withgrub" variable, if set. The "grubonly" configuration is retained, and enabled by default when SeaGRUB is enabled (non-grubonly also available). Due to lbmk issue #216, it is no longer Libreboot policy to make GRUB the primary payload on any board. GRUB's sheer size and complexity, plus the large number of memory corruption issues similar to it that *have* been fixed over the years, tells me that GRUB is a liability when it is the primary payload. SeaBIOS is a much safer payload to run as primary, on x86, due to its smaller size and much more conservative development; it is simply far less likely to break. If GRUB breaks in the future, the user's machine is not bricked. This is because SeaBIOS is the default payload. Since I no longer wish to ever provide GRUB as a primary payload, supporting it in lbmk adds needless bloat that will later probably break anyway due to lack of testing, so let's just assume SeaGRUB in all cases where the user wants to use a GRUB payload. You can mitigate potential security issues with SeaBIOS by disabling option ROM execution, which can be done at runtime by inserting integers into CBFS. The SeaBIOS documentation says how to do this. Libreboot's GRUB hardening guide still says how to add a bootorder file in CBFS, making SeaBIOS only load GRUB from CBFS, and nothing else. This, combined with the disablement of option ROM execution (if using Intel graphics), pretty much provides the same security benefits as GRUB-as-primary, for example when setting a GRUB password and GPG checks, with encrypted /boot as in the hardening guide. Signed-off-by: Leah Rowe <leah@libreboot.org>
Diffstat (limited to 'script')
-rwxr-xr-xscript/roms87
1 files changed, 30 insertions, 57 deletions
diff --git a/script/roms b/script/roms
index 213f1b1f..92f79db4 100755
--- a/script/roms
+++ b/script/roms
@@ -22,10 +22,9 @@ stm32dir="$stm32src/boards"
# Disable all payloads by default.
# target.cfg files have to specifically enable [a] payload(s)
-pv="payload_uboot payload_grub_withseabios payload_seabios payload_memtest t"
-pv="$pv payload_seabios_withgrub payload_grub"
+pv="payload_uboot payload_seabios payload_memtest t payload_grub"
v="romdir cbrom initmode displaymode cbcfg targetdir tree release ubootelf"
-v="$v grub_timeout board grub_scan_disk uboot_config grubtree grubelf tmpmv"
+v="$v board grub_scan_disk uboot_config grubtree grubelf tmpmv"
eval `setvars "n" $pv`
eval `setvars "" $v boards targets serdir ser`
@@ -97,30 +96,24 @@ configure_target()
# Override the above defaults using target.cfg
eval `setcfg "$targetdir/target.cfg"`
+ [ -z "$tree" ] && $err "$board: tree not defined"
+ [ "$xbmk_release" = "y" ] && [ "$release" = "n" ] && return 1
+ [ "$board" = "$tree" ] && return 1
+
+ [ -n "$uboot_config" ] || uboot_config="default"
+ [ "$payload_uboot" = "y" ] || payload_seabios="y"
+ [ "$payload_grub" = "y" ] && payload_seabios="y"
+ [ "$payload_seabios" = "y" ] && [ -n "$payload_uboot" = "y" ] && \
+ $err "$board: U-Boot and SeaBIOS/GRUB are both enabled."
+
[ -z "$grub_scan_disk" ] && grub_scan_disk="nvme ahci ata"
[ -n "$grubtree" ] || grubtree="default"
grubelf="elf/grub/$grubtree/payload/grub.elf"
- [ -z "$tree" ] && $err "$board: tree not defined"
-
- [ "$payload_memtest" != "y" ] && payload_memtest="n"
+ [ "$payload_memtest" = "y" ] || payload_memtest="n"
[ "$(uname -m)" = "x86_64" ] || payload_memtest="n"
-
- [ "$payload_grub_withseabios" = "y" ] && eval `setvars "y" \
- payload_grub payload_seabios payload_seabios_withgrub`
- [ "$payload_seabios_withgrub" = "y" ] && payload_seabios="y"
-
- # The reverse logic must not be applied. If SeaBIOS-with-GRUB works,
- # that doesn't mean GRUB-with-SeaBIOS will, e.g. VGA ROM execution
- [ "$payload_grub" != "y" ] && [ "$payload_seabios" != "y" ] && \
- [ "$payload_uboot" != "y" ] && $err "'$board' defines no payload"
-
- [ "$payload_uboot" = "y" ] || payload_uboot="n"
- [ -n "$uboot_config" ] || uboot_config="default"
-
- [ "$xbmk_release" = "y" ] && [ "$release" = "n" ] && return 1
- [ "$board" = "$tree" ] && return 1; return 0
+ [ "$payload_uboot" = "y" ] && payload_memtest="n"; return 0
}
build_payloads()
@@ -134,11 +127,7 @@ build_payloads()
[ -f "$cbfstool" ] || x_ ./update trees -b coreboot utils $tree
[ "$payload_memtest" = "y" ] && x_ ./update trees -b memtest86plus
[ "$payload_seabios" = "y" ] && x_ ./update trees -b seabios
-
- if [ "$payload_grub" = "y" ] || [ "$payload_seabios_withgrub" = "y" ]
- then
- [ -f "$grubelf" ] || x_ ./update trees -b grub $grubtree
- fi
+ [ "$payload_grub" = "y" ] && x_ ./update trees -b grub $grubtree
[ "$payload_uboot" = "y" ] || return 0
x_ ./update trees -b u-boot $board
@@ -181,19 +170,18 @@ build_roms()
[ "$payload_memtest" != "y" ] || cbfs "$cbrom" \
"elf/memtest86plus/memtest.bin" img/memtest
[ "$payload_seabios" = "y" ] && build_seabios_roms
- [ "$payload_grub" != "y" ] || build_grub_roms "$cbrom" "grub"
[ "$payload_uboot" = "y" ] && x_ cp "$_cbrom" "$cbrom" && \
build_uboot_roms; return 0
}
build_seabios_roms()
{
- if [ "$payload_seabios_withgrub" = "y" ]; then
+ if [ "$payload_grub" = "y" ]; then # SeaBIOS with GRUB
t="$(mktemp -t coreboot_rom.XXXXXXXXXX)"
x_ cp "$cbrom" "$t"
- build_grub_roms "$t" "seabios_withgrub"
- else
- t="$(mkSeabiosRom "$cbrom" "fallback/payload")" || \
+ build_seagrub_roms "$t" "seabios_withgrub"
+ else # SeaBIOS only
+ t="$(mkSeabiosRom "$cbrom")" || \
$err "build_seabios_roms: cannot build tmprom"
newrom="$romdir/seabios_${board}_${initmode}_$displaymode"
[ "$initmode" = "normal" ] && newrom="$romdir/seabios" \
@@ -203,40 +191,25 @@ build_seabios_roms()
x_ rm -f "$t"
}
-# Make separate ROM images with GRUB payload
-build_grub_roms()
+build_seagrub_roms()
{
- tmprom="$1"
- payload1="$2" # allow values: grub, seabios, seabios_withgrub
-
- grub_cbfs="fallback/payload"
- if [ "$payload1" = "grub" ] && [ "$payload_grub_withseabios" = "y" ]
- then
- tmpmv="$(mkSeabiosRom "$tmprom" "seabios.elf")" || \
- $err "build_grub_roms 1 $board: can't build tmprom"
- elif [ "$payload1" != "grub" ] && [ "$payload_seabios_withgrub" = "y" ]
- then
- grub_cbfs="img/grub2"
- tmpmv="$(mkSeabiosRom "$tmprom" fallback/payload)" || \
- $err "build_grub_roms 2 $board: can't build tmprom"
- fi
- [ -n "$tmpmv" ] && [ -f "$tmpmv" ] && x_ mv "$tmpmv" "$tmprom"
+ tmpmv="$(mkSeabiosRom "$1")" || $err "$board: !mk grub tmprom"
+ x_ mv "$tmpmv" "$1"
# we only need insert grub.elf once, for each coreboot config:
- cbfs "$tmprom" "$grubelf" "$grub_cbfs"
+ cbfs "$1" "$grubelf" "img/grub2"
printf "set grub_scan_disk=\"%s\"\n" "$grub_scan_disk" \
> "$tmpdir/tmpcfg" || $err "set grub_scan_disk, $grub_scan_disk"
- cbfs "$tmprom" "$tmpdir/tmpcfg" scan.cfg raw
+ cbfs "$1" "$tmpdir/tmpcfg" scan.cfg raw
- newrom="$romdir/${payload1}_${board}_${initmode}_$displaymode.rom"
- [ "$initmode" = "normal" ] && newrom="$romdir/${payload1}_" \
+ newrom="$romdir/seabios_withgrub_${board}_${initmode}_$displaymode.rom"
+ [ "$initmode" = "normal" ] && newrom="$romdir/seabios_withgrub_" \
&& newrom="$newrom${board}_$initmode.rom"
- cprom cp "$tmprom" "$newrom"
+ cprom cp "$1" "$newrom"
- [ "$payload1" = "grub" ] && return 0
- cbfs "$tmprom" "$grubdata/bootorder" bootorder raw
- cprom cp "$tmprom" "${newrom%.rom}_grubfirst.rom"
+ cbfs "$1" "$grubdata/bootorder" bootorder raw # SeaGRUB
+ cprom cp "$1" "${newrom%.rom}_grubfirst.rom"
}
# make a rom in /tmp/ and then print the path of that ROM
@@ -245,7 +218,7 @@ mkSeabiosRom() {
_seabioself="elf/seabios/default/$initmode/bios.bin.elf"
x_ cp "$1" "$tmprom"
- cbfs "$tmprom" "$_seabioself" "$2"
+ cbfs "$tmprom" "$_seabioself" "fallback/payload"
x_ "$cbfstool" "$tmprom" add-int -i 3000 -n etc/ps2-keyboard-spinup
z="2"; [ "$initmode" = "vgarom" ] && z="0"