mirror of
https://github.com/linuxboot/heads.git
synced 2024-12-20 21:43:11 +00:00
105 lines
4.1 KiB
Bash
Executable File
105 lines
4.1 KiB
Bash
Executable File
#!/bin/bash
|
|
|
|
# If blob jail is enabled, copy initrd and inject firmware.
|
|
# Prints new initrd path (in memory) if firmware was injected.
|
|
#
|
|
# This does not alter the initrd on disk:
|
|
# * Signatures are not invalidated
|
|
# * If the injection fails for any reason, we just proceed with the original
|
|
# initrd (lacking firmware, but still booting).
|
|
# * If, somehow, this injection malfunctions (without failing outright) and
|
|
# prevents a boot, the user can work around it just by disabling blob jail.
|
|
# We do not risk ruining the real initrd.
|
|
#
|
|
# The injection has some requirements on the initrd that are all true for
|
|
# Debian:
|
|
# * initrd must be a gzipped cpio (Linux supports other compression methods)
|
|
# * /init must be a shell script (so we can inject a command to copy firmware)
|
|
# * There must be an 'exec run-init ... ${rootmnt} ...' line that moves the
|
|
# real root to / and invokes init
|
|
#
|
|
# If the injection can't be performed, boot will continue with no firmware.
|
|
|
|
set -e -o pipefail
|
|
|
|
. /tmp/config
|
|
. /etc/functions
|
|
|
|
if [ "$(load_config_value CONFIG_USE_BLOB_JAIL)" != "y" ]; then
|
|
# Blob jail not active, nothing to do
|
|
exit 0
|
|
fi
|
|
|
|
ORIG_INITRD="$1"
|
|
|
|
# Extract the init script from the initrd
|
|
INITRD_ROOT="/tmp/inject_firmware_initrd_root"
|
|
rm -rf "$INITRD_ROOT" || true
|
|
mkdir "$INITRD_ROOT"
|
|
# Unpack just 'init' from the original initrd
|
|
unpack_initramfs.sh "$ORIG_INITRD" "$INITRD_ROOT" init
|
|
|
|
# Copy the firmware into the initrd
|
|
for f in $(cbfs -l | grep firmware); do
|
|
mkdir -p "$INITRD_ROOT/$(dirname "$f")"
|
|
cbfs -r "$f" > "$INITRD_ROOT/$f"
|
|
if [[ "$f" == *.lzma ]]; then
|
|
lzma -d "$INITRD_ROOT/$f"
|
|
fi
|
|
done
|
|
|
|
# awk will happily pass through a binary file, so look for the match we want
|
|
# before modifying init to ensure it's a shell script and not an ELF, etc.
|
|
if ! grep -E -q '^exec run-init .*\$\{rootmnt\}' "$INITRD_ROOT/init"; then
|
|
warn "Can't apply firmware blob jail, unknown init script"
|
|
exit 0
|
|
fi
|
|
|
|
# In general, firmware files must be available _both_ during the initrd _and_
|
|
# once root is moved to /. Firmware loading may happen in either phase (e.g.
|
|
# i915 GUC firmware is usually loaded in the initrd because i915 is used there,
|
|
# but Wi-Fi/BT modules typically are not in the initrd, they're loaded later).
|
|
#
|
|
# We want to place the firmware after boot in /run, since this is a tmpfs mount
|
|
# - it works even if the root filesystem is read-only and does not persist
|
|
# anything. But we cannot place it there for the initrd, since the initrd also
|
|
# mounts a tmpfs on /run. We can only specify one custom firmware path, but we
|
|
# can change it at runtime.
|
|
#
|
|
# So during the initrd, the firmware is in /firmware, and we provide that path
|
|
# on the kernel command line. Just before invoking the real init (after root is
|
|
# mounted), we copy it to /run/firmware and also change the firmware path.
|
|
#
|
|
# Debian's init script ends with an "exec run-init ..." (followed by a few lines
|
|
# to print a message in case it fails). At that point, root is mounted, and
|
|
# run-init will move it to / and then exec init. We can insert the firmware
|
|
# actions just before that, so we don't have to know anything about how root was
|
|
# mounted.
|
|
#
|
|
# The root path is in ${rootmnt}, which should appear in the run-init command.
|
|
# If it doesn't, then we don't understand the init script.
|
|
AWK_INSERT_CP='
|
|
BEGIN{inserted=0}
|
|
/^exec run-init .*\$\{rootmnt\}/ && inserted==0 {
|
|
print "cp -r /firmware ${rootmnt}/run/firmware"
|
|
print "echo -n /run/firmware >${rootmnt}/sys/module/firmware_class/parameters/path"
|
|
inserted=1
|
|
}
|
|
{print $0}'
|
|
|
|
awk -e "$AWK_INSERT_CP" "$INITRD_ROOT/init" >"$INITRD_ROOT/init_fw"
|
|
mv "$INITRD_ROOT/init_fw" "$INITRD_ROOT/init"
|
|
chmod a+x "$INITRD_ROOT/init"
|
|
|
|
# Pad the original initrd to 512 byte blocks. Uncompressed cpio contents must
|
|
# be 4-byte aligned, and anecdotally gzip frames might not be padded by dracut.
|
|
# Linux ignores zeros between archive segments, so any extra padding is not
|
|
# harmful.
|
|
FW_INITRD="/tmp/inject_firmware_initrd.cpio.gz"
|
|
dd if="$ORIG_INITRD" of="$FW_INITRD" bs=512 conv=sync status=none
|
|
# Pack up the new contents and append to the initrd. Don't spend time
|
|
# compressing this.
|
|
(cd "$INITRD_ROOT"; find . | cpio -o -H newc) >>"$FW_INITRD"
|
|
# Use this initrd
|
|
echo "$FW_INITRD"
|