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72 lines
2.3 KiB
Bash
Executable File
72 lines
2.3 KiB
Bash
Executable File
#!/bin/bash
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# Retrieve the sealed file and counter from the NVRAM, unseal it and compute the hotp
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. /etc/functions
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HOTP_SECRET="/tmp/secret/hotp.key"
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HOTP_COUNTER="/boot/kexec_hotp_counter"
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mount_boot_or_die() {
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TRACE_FUNC
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# Mount local disk if it is not already mounted
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if ! grep -q /boot /proc/mounts; then
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mount -o ro /boot ||
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die "Unable to mount /boot"
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fi
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}
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TRACE_FUNC
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# Store counter in file instead of TPM for now, as it conflicts with Heads
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# config TPM counter as TPM 1.2 can only increment one counter between reboots
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# get current value of HOTP counter in TPM, create if absent
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mount_boot_or_die
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#check_tpm_counter $HOTP_COUNTER hotp \
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#|| die "Unable to find/create TPM counter"
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#counter="$TPM_COUNTER"
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#
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#counter_value=$(read_tpm_counter $counter | cut -f2 -d ' ' | awk 'gsub("^000e","")')
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#
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counter_value=$(cat $HOTP_COUNTER)
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if [ "$counter_value" == "" ]; then
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die "Unable to read HOTP counter"
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fi
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#counter_value=$(printf "%d" 0x${counter_value})
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if [ "$CONFIG_TPM" = "y" ]; then
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DEBUG "Unsealing HOTP secret reuses TOTP sealed secret..."
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tpmr unseal 4d47 0,1,2,3,4,7 312 "$HOTP_SECRET" || die "Unable to unseal HOTP secret"
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else
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# without a TPM, generate a secret based on the SHA-256 of the ROM
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secret_from_rom_hash >"$HOTP_SECRET" || die "Reading ROM failed"
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fi
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# Truncate the secret if it is longer than the maximum HOTP secret
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truncate_max_bytes 20 "$HOTP_SECRET"
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if ! hotp $counter_value <"$HOTP_SECRET"; then
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shred -n 10 -z -u "$HOTP_SECRET" 2>/dev/null
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die 'Unable to compute HOTP hash?'
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fi
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shred -n 10 -z -u "$HOTP_SECRET" 2>/dev/null
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#Incrementing counter under $HOTP_COUNTER
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#
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# If for whatever reason, this counter is 5 counts different then on HOTP USB Security dongle, HOTP unseal fails.
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#Note: HOTP_COUNTER="/boot/kexec_hotp_counter" is not detached signed under kexec.sig since it changes
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#
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# TODO: figure out a better alternative then a counter that can be modified on disk
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# As of now, this counter isincreased only in the validated presence of the HOTP dongle being connected per callers
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mount -o remount,rw /boot
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DEBUG "Incrementing HOTP counter under $HOTP_COUNTER"
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counter_value=$(expr $counter_value + 1)
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echo $counter_value >$HOTP_COUNTER ||
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die "Unable to create hotp counter file"
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mount -o remount,ro /boot
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exit 0
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