mirror of
https://github.com/speed47/spectre-meltdown-checker.git
synced 2026-04-09 18:23:20 +02:00
split script in multiple files, reassembled through build.sh
This commit is contained in:
Stéphane Lesimple
152
src/libs/300_kernel_extract.sh
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152
src/libs/300_kernel_extract.sh
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# vim: set ts=4 sw=4 sts=4 et:
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# The 3 below functions are taken from the extract-linux script, available here:
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# https://github.com/torvalds/linux/blob/master/scripts/extract-vmlinux
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# The functions have been modified for better integration to this script
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# The original header of the file has been retained below
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# ----------------------------------------------------------------------
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# extract-vmlinux - Extract uncompressed vmlinux from a kernel image
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#
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# Inspired from extract-ikconfig
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# (c) 2009,2010 Dick Streefland <dick@streefland.net>
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#
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# (c) 2011 Corentin Chary <corentin.chary@gmail.com>
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#
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# Licensed under the GNU General Public License, version 2 (GPLv2).
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# ----------------------------------------------------------------------
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g_kernel=''
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g_kernel_err=''
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# Validate whether a file looks like a valid uncompressed Linux kernel image
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# Args: $1=file_path
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# Sets: g_kernel, g_kernel_err
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check_kernel() {
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local ret file mode readelf_warnings readelf_sections kernel_size
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file="$1"
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mode="${2:-normal}"
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# checking the return code of readelf -h is not enough, we could get
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# a damaged ELF file and validate it, check for stderr warnings too
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# the warning "readelf: Warning: [16]: Link field (0) should index a symtab section./" can appear on valid kernels, ignore it
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readelf_warnings=$("${opt_arch_prefix}readelf" -S "$file" 2>&1 >/dev/null | grep -v 'should index a symtab section' | tr "\n" "/")
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ret=$?
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readelf_sections=$("${opt_arch_prefix}readelf" -S "$file" 2>/dev/null | grep -c -e data -e text -e init)
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kernel_size=$(stat -c %s "$file" 2>/dev/null || stat -f %z "$file" 2>/dev/null || echo 10000)
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pr_debug "check_kernel: ret=$? size=$kernel_size sections=$readelf_sections warnings=$readelf_warnings"
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if [ "$mode" = desperate ]; then
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if "${opt_arch_prefix}strings" "$file" | grep -Eq '^Linux version '; then
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pr_debug "check_kernel (desperate): ... matched!"
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if [ "$readelf_sections" = 0 ] && grep -qF -e armv6 -e armv7 "$file"; then
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pr_debug "check_kernel (desperate): raw arm binary found, adjusting objdump options"
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g_objdump_options="-D -b binary -marm"
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else
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g_objdump_options="-d"
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fi
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return 0
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else
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pr_debug "check_kernel (desperate): ... invalid"
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fi
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else
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if [ $ret -eq 0 ] && [ -z "$readelf_warnings" ] && [ "$readelf_sections" -gt 0 ]; then
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if [ "$kernel_size" -ge 100000 ]; then
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pr_debug "check_kernel: ... file is valid"
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g_objdump_options="-d"
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return 0
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else
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pr_debug "check_kernel: ... file seems valid but is too small, ignoring"
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fi
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else
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pr_debug "check_kernel: ... file is invalid"
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fi
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fi
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return 1
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}
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# Attempt to find and decompress a kernel image using a given compression format
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# Args: $1=magic_search $2=magic_match $3=format_name $4=decompress_cmd $5=decompress_args $6=input_file $7=output_file
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try_decompress() {
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local pos ret
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# The obscure use of the "tr" filter is to work around older versions of
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# "grep" that report the byte offset of the line instead of the pattern.
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# Try to find the header ($1) and decompress from here
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pr_debug "try_decompress: looking for $3 magic in $6"
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for pos in $(tr "$1\n$2" "\n$2=" <"$6" | grep -abo "^$2"); do
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pr_debug "try_decompress: magic for $3 found at offset $pos"
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if ! command -v "$3" >/dev/null 2>&1; then
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if [ "$8" = 1 ]; then
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# pass1: if the tool is not installed, just bail out silently
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# and hope that the next decompression tool will be, and that
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# it'll happen to be the proper one for this kernel
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pr_debug "try_decompress: the '$3' tool is not installed (pass 1), try the next algo"
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else
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# pass2: if the tool is not installed, populate g_kernel_err this time
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g_kernel_err="missing '$3' tool, please install it, usually it's in the '$5' package"
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pr_debug "try_decompress: $g_kernel_err"
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fi
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return 1
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fi
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pos=${pos%%:*}
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# shellcheck disable=SC2086
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tail -c+$pos "$6" 2>/dev/null | $3 $4 >"$g_kerneltmp" 2>/dev/null
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ret=$?
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if [ ! -s "$g_kerneltmp" ]; then
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# don't rely on $ret, sometimes it's != 0 but worked
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# (e.g. gunzip ret=2 just means there was trailing garbage)
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pr_debug "try_decompress: decompression with $3 failed (err=$ret)"
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elif check_kernel "$g_kerneltmp" "$7"; then
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g_kernel="$g_kerneltmp"
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pr_debug "try_decompress: decompressed with $3 successfully!"
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return 0
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elif [ "$3" != "cat" ]; then
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pr_debug "try_decompress: decompression with $3 worked but result is not a kernel, trying with an offset"
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[ -z "$g_kerneltmp2" ] && g_kerneltmp2=$(mktemp -t smc-kernel-XXXXXX)
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cat "$g_kerneltmp" >"$g_kerneltmp2"
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try_decompress '\177ELF' xxy 'cat' '' cat "$g_kerneltmp2" && return 0
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else
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pr_debug "try_decompress: decompression with $3 worked but result is not a kernel"
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fi
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done
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return 1
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}
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# Extract an uncompressed vmlinux from a possibly compressed kernel image
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# Args: $1=kernel_image_path
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# Sets: g_kerneltmp
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extract_kernel() {
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local pass mode
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[ -n "${1:-}" ] || return 1
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# Prepare temp files:
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g_kerneltmp="$(mktemp -t smc-kernel-XXXXXX)"
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# Initial attempt for uncompressed images or objects:
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if check_kernel "$1"; then
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pr_debug "extract_kernel: found kernel is valid, no decompression needed"
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cat "$1" >"$g_kerneltmp"
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g_kernel=$g_kerneltmp
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return 0
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fi
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# That didn't work, so retry after decompression.
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for pass in 1 2; do
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for mode in normal desperate; do
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pr_debug "extract_kernel: pass $pass $mode mode"
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try_decompress '\037\213\010' xy gunzip '' gunzip "$1" "$mode" "$pass" && return 0
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try_decompress '\002\041\114\030' xyy 'lz4' '-d -l' liblz4-tool "$1" "$mode" "$pass" && return 0
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try_decompress '\3757zXZ\000' abcde unxz '' xz-utils "$1" "$mode" "$pass" && return 0
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try_decompress 'BZh' xy bunzip2 '' bzip2 "$1" "$mode" "$pass" && return 0
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try_decompress '\135\0\0\0' xxx unlzma '' xz-utils "$1" "$mode" "$pass" && return 0
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try_decompress '\211\114\132' xy 'lzop' '-d' lzop "$1" "$mode" "$pass" && return 0
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try_decompress '\177ELF' xxy 'cat' '' cat "$1" "$mode" "$pass" && return 0
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try_decompress '(\265/\375' xxy unzstd '' zstd "$1" "$mode" "$pass" && return 0
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done
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done
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# g_kernel_err might already have been populated by try_decompress() if we're missing one of the tools
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if [ -z "$g_kernel_err" ]; then
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g_kernel_err="kernel compression format is unknown or image is invalid"
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fi
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pr_verbose "Couldn't extract the kernel image ($g_kernel_err), accuracy might be reduced"
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return 1
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}
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# end of extract-vmlinux functions
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