fix: prevent tar symlink traversal in archive extraction
Archives passed to git:from-archive and certs:add were extracted without symlink or path validation, allowing a crafted archive to write arbitrary files anywhere writable by the dokku user via symlink traversal. Extraction now pre-scans entries for absolute paths, parent traversal, and unsafe symlinks, applies the GNU tar `--no-unsafe-links` flag when available, and validates symlinks after extraction.
This commit is contained in:
Jose Diaz-Gonzalez
@@ -44,7 +44,7 @@ cmd-certs-set() {
|
||||
local CERTS_SET_TMP_WORK_DIR=$(mktemp -d "/tmp/dokku-${DOKKU_PID}-${FUNCNAME[0]}.XXXXXX")
|
||||
pushd "$CERTS_SET_TMP_WORK_DIR" &>/dev/null
|
||||
trap "popd &>/dev/null || true; rm -rf '$CERTS_SET_TMP_WORK_DIR' >/dev/null" RETURN
|
||||
tar xvf - <&0
|
||||
fn-archive-extract-tar-stdin "$CERTS_SET_TMP_WORK_DIR" "certs:add"
|
||||
|
||||
local CRT_FILE_SEARCH=$(find . -not -path '*/\.*' -type f | grep ".crt$")
|
||||
local CRT_FILE_COUNT=$(printf "%s" "$CRT_FILE_SEARCH" | grep -c '^')
|
||||
|
||||
196
plugins/common/archive-functions
Executable file
196
plugins/common/archive-functions
Executable file
@@ -0,0 +1,196 @@
|
||||
#!/usr/bin/env bash
|
||||
set -eo pipefail
|
||||
[[ $DOKKU_TRACE ]] && set -x
|
||||
|
||||
DOKKU_ARCHIVE_MAX_SIZE="${DOKKU_ARCHIVE_MAX_SIZE:-1073741824}"
|
||||
DOKKU_ARCHIVE_MAX_FILES="${DOKKU_ARCHIVE_MAX_FILES:-10000}"
|
||||
|
||||
fn-archive-log-security-event() {
|
||||
declare desc="logs an archive security event for auditing"
|
||||
declare EVENT="$1" ARCHIVE_TYPE="$2" SOURCE="$3" DETAILS="$4"
|
||||
local TIMESTAMP="$(date -u +"%Y-%m-%dT%H:%M:%SZ")"
|
||||
local USERNAME="${SUDO_USER:-${USER:-unknown}}"
|
||||
echo "[archive-security] timestamp=${TIMESTAMP} user=${USERNAME} event=${EVENT} archive_type=${ARCHIVE_TYPE} source=${SOURCE} details=${DETAILS}" 1>&2
|
||||
}
|
||||
|
||||
fn-archive-tar-flag() {
|
||||
declare desc="returns the appropriate decompression flag for tar based on archive type"
|
||||
declare ARCHIVE_TYPE="$1"
|
||||
case "$ARCHIVE_TYPE" in
|
||||
tar) echo "" ;;
|
||||
tar.gz) echo "-z" ;;
|
||||
*) return 1 ;;
|
||||
esac
|
||||
}
|
||||
|
||||
fn-archive-check-bomb-protection() {
|
||||
declare desc="validates archive against bomb protection limits"
|
||||
declare ARCHIVE_PATH="$1" ARCHIVE_TYPE="$2"
|
||||
local ARCHIVE_SIZE
|
||||
ARCHIVE_SIZE="$(stat -c %s "$ARCHIVE_PATH" 2>/dev/null || stat -f %z "$ARCHIVE_PATH" 2>/dev/null || echo 0)"
|
||||
|
||||
if [[ "$ARCHIVE_SIZE" -gt "$DOKKU_ARCHIVE_MAX_SIZE" ]]; then
|
||||
fn-archive-log-security-event "rejected_archive_too_large" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "size=${ARCHIVE_SIZE} max=${DOKKU_ARCHIVE_MAX_SIZE}"
|
||||
dokku_log_fail "Archive exceeds maximum allowed size of ${DOKKU_ARCHIVE_MAX_SIZE} bytes"
|
||||
fi
|
||||
|
||||
local TAR_FLAG
|
||||
TAR_FLAG="$(fn-archive-tar-flag "$ARCHIVE_TYPE")" || return 0
|
||||
|
||||
local FILE_COUNT
|
||||
if [[ -n "$TAR_FLAG" ]]; then
|
||||
FILE_COUNT="$(tar "$TAR_FLAG" -tf "$ARCHIVE_PATH" 2>/dev/null | wc -l)"
|
||||
else
|
||||
FILE_COUNT="$(tar -tf "$ARCHIVE_PATH" 2>/dev/null | wc -l)"
|
||||
fi
|
||||
|
||||
if [[ "$FILE_COUNT" -gt "$DOKKU_ARCHIVE_MAX_FILES" ]]; then
|
||||
fn-archive-log-security-event "rejected_archive_too_many_files" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "count=${FILE_COUNT} max=${DOKKU_ARCHIVE_MAX_FILES}"
|
||||
dokku_log_fail "Archive contains ${FILE_COUNT} entries which exceeds the maximum of ${DOKKU_ARCHIVE_MAX_FILES}"
|
||||
fi
|
||||
}
|
||||
|
||||
fn-archive-validate-tar-entries() {
|
||||
declare desc="pre-scans a tar archive for dangerous path entries"
|
||||
declare ARCHIVE_PATH="$1" ARCHIVE_TYPE="$2"
|
||||
local TAR_FLAG NAMES VERBOSE
|
||||
TAR_FLAG="$(fn-archive-tar-flag "$ARCHIVE_TYPE")" || dokku_log_fail "Unsupported archive type for validation: ${ARCHIVE_TYPE}"
|
||||
|
||||
if [[ -n "$TAR_FLAG" ]]; then
|
||||
NAMES="$(tar "$TAR_FLAG" -tf "$ARCHIVE_PATH" 2>/dev/null)"
|
||||
VERBOSE="$(tar "$TAR_FLAG" -tvf "$ARCHIVE_PATH" 2>/dev/null)"
|
||||
else
|
||||
NAMES="$(tar -tf "$ARCHIVE_PATH" 2>/dev/null)"
|
||||
VERBOSE="$(tar -tvf "$ARCHIVE_PATH" 2>/dev/null)"
|
||||
fi
|
||||
|
||||
if echo "$NAMES" | grep -qE '^/'; then
|
||||
fn-archive-log-security-event "rejected_absolute_path" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "absolute path detected"
|
||||
dokku_log_fail "Archive contains entries with absolute paths"
|
||||
fi
|
||||
|
||||
if echo "$NAMES" | grep -qE '(^|/)\.\.(/|$)'; then
|
||||
fn-archive-log-security-event "rejected_path_traversal" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "parent directory traversal detected"
|
||||
dokku_log_fail "Archive contains entries with parent directory traversal"
|
||||
fi
|
||||
|
||||
while IFS= read -r entry; do
|
||||
[[ -z "$entry" ]] && continue
|
||||
[[ "${entry:0:1}" != "l" ]] && continue
|
||||
local target="${entry##*-> }"
|
||||
case "$target" in
|
||||
/*)
|
||||
fn-archive-log-security-event "rejected_unsafe_symlink" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "absolute symlink target=${target}"
|
||||
dokku_log_fail "Archive contains symlinks with absolute targets"
|
||||
;;
|
||||
*..*)
|
||||
fn-archive-log-security-event "rejected_unsafe_symlink" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "traversal symlink target=${target}"
|
||||
dokku_log_fail "Archive contains symlinks pointing outside extraction directory"
|
||||
;;
|
||||
esac
|
||||
done <<<"$VERBOSE"
|
||||
}
|
||||
|
||||
fn-archive-validate-extracted-symlinks() {
|
||||
declare desc="validates that no symlinks in the extraction directory point outside it"
|
||||
declare EXTRACTION_DIR="$1"
|
||||
local CANONICAL_DIR
|
||||
CANONICAL_DIR="$(readlink -f "$EXTRACTION_DIR")"
|
||||
|
||||
local SYMLINKS
|
||||
SYMLINKS="$(find "$EXTRACTION_DIR" -type l 2>/dev/null || true)"
|
||||
[[ -z "$SYMLINKS" ]] && return 0
|
||||
|
||||
while IFS= read -r link; do
|
||||
[[ -z "$link" ]] && continue
|
||||
local target
|
||||
target="$(readlink -f "$link" 2>/dev/null || echo "")"
|
||||
if [[ -z "$target" ]] || [[ "$target" != "$CANONICAL_DIR"* ]]; then
|
||||
fn-archive-log-security-event "rejected_extracted_symlink" "post_extraction" "$link" "target=${target} dir=${CANONICAL_DIR}"
|
||||
dokku_log_fail "Archive contains symlinks pointing outside extraction directory"
|
||||
fi
|
||||
done <<<"$SYMLINKS"
|
||||
}
|
||||
|
||||
fn-archive-tar-supports-no-unsafe-links() {
|
||||
declare desc="returns 0 if the tar binary supports --no-unsafe-links"
|
||||
if tar --help 2>&1 | grep -q -- "--no-unsafe-links"; then
|
||||
return 0
|
||||
fi
|
||||
return 1
|
||||
}
|
||||
|
||||
fn-archive-extract-tar() {
|
||||
declare desc="safely extracts a tar archive with symlink protection"
|
||||
declare ARCHIVE_PATH="$1" DEST_DIR="$2" ARCHIVE_TYPE="$3" STRIP_COMPONENTS="${4:-0}"
|
||||
local TAR_FLAG
|
||||
TAR_FLAG="$(fn-archive-tar-flag "$ARCHIVE_TYPE")" || dokku_log_fail "Unsupported archive type for extraction: ${ARCHIVE_TYPE}"
|
||||
|
||||
fn-archive-check-bomb-protection "$ARCHIVE_PATH" "$ARCHIVE_TYPE"
|
||||
fn-archive-validate-tar-entries "$ARCHIVE_PATH" "$ARCHIVE_TYPE"
|
||||
|
||||
fn-archive-log-security-event "extraction_started" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "dest=${DEST_DIR}"
|
||||
|
||||
local TAR_ARGS=()
|
||||
if fn-archive-tar-supports-no-unsafe-links; then
|
||||
TAR_ARGS+=("--no-unsafe-links")
|
||||
fi
|
||||
if [[ "$STRIP_COMPONENTS" -gt 0 ]]; then
|
||||
TAR_ARGS+=("--strip-components=$STRIP_COMPONENTS")
|
||||
fi
|
||||
|
||||
if [[ -n "$TAR_FLAG" ]] && [[ "${#TAR_ARGS[@]}" -gt 0 ]]; then
|
||||
tar -x "$TAR_FLAG" -C "$DEST_DIR" -f "$ARCHIVE_PATH" "${TAR_ARGS[@]}"
|
||||
elif [[ -n "$TAR_FLAG" ]]; then
|
||||
tar -x "$TAR_FLAG" -C "$DEST_DIR" -f "$ARCHIVE_PATH"
|
||||
elif [[ "${#TAR_ARGS[@]}" -gt 0 ]]; then
|
||||
tar -x -C "$DEST_DIR" -f "$ARCHIVE_PATH" "${TAR_ARGS[@]}"
|
||||
else
|
||||
tar -x -C "$DEST_DIR" -f "$ARCHIVE_PATH"
|
||||
fi
|
||||
|
||||
fn-archive-validate-extracted-symlinks "$DEST_DIR"
|
||||
fn-archive-log-security-event "extraction_completed" "$ARCHIVE_TYPE" "$ARCHIVE_PATH" "dest=${DEST_DIR}"
|
||||
}
|
||||
|
||||
fn-archive-extract-tar-stdin() {
|
||||
declare desc="safely extracts a tar archive from stdin into the current directory"
|
||||
declare DEST_DIR="$1" SOURCE_LABEL="${2:-stdin}"
|
||||
|
||||
local STDIN_TMP
|
||||
STDIN_TMP="$(mktemp "/tmp/dokku-${DOKKU_PID}-archive.XXXXXX")"
|
||||
trap "rm -f '$STDIN_TMP' >/dev/null 2>&1 || true" RETURN
|
||||
|
||||
cat <&0 >"$STDIN_TMP"
|
||||
fn-archive-extract-tar "$STDIN_TMP" "$DEST_DIR" "tar" 0
|
||||
rm -f "$STDIN_TMP" >/dev/null 2>&1 || true
|
||||
}
|
||||
|
||||
fn-archive-extract-zip() {
|
||||
declare desc="safely extracts a zip archive with post-extraction symlink validation"
|
||||
declare ARCHIVE_PATH="$1" DEST_DIR="$2"
|
||||
|
||||
local ARCHIVE_SIZE
|
||||
ARCHIVE_SIZE="$(stat -c %s "$ARCHIVE_PATH" 2>/dev/null || stat -f %z "$ARCHIVE_PATH" 2>/dev/null || echo 0)"
|
||||
if [[ "$ARCHIVE_SIZE" -gt "$DOKKU_ARCHIVE_MAX_SIZE" ]]; then
|
||||
fn-archive-log-security-event "rejected_archive_too_large" "zip" "$ARCHIVE_PATH" "size=${ARCHIVE_SIZE} max=${DOKKU_ARCHIVE_MAX_SIZE}"
|
||||
dokku_log_fail "Archive exceeds maximum allowed size of ${DOKKU_ARCHIVE_MAX_SIZE} bytes"
|
||||
fi
|
||||
|
||||
local FILE_COUNT
|
||||
FILE_COUNT="$(unzip -l "$ARCHIVE_PATH" 2>/dev/null | tail -n 1 | awk '{print $2}')"
|
||||
if [[ -n "$FILE_COUNT" ]] && [[ "$FILE_COUNT" -gt "$DOKKU_ARCHIVE_MAX_FILES" ]]; then
|
||||
fn-archive-log-security-event "rejected_archive_too_many_files" "zip" "$ARCHIVE_PATH" "count=${FILE_COUNT} max=${DOKKU_ARCHIVE_MAX_FILES}"
|
||||
dokku_log_fail "Archive contains ${FILE_COUNT} entries which exceeds the maximum of ${DOKKU_ARCHIVE_MAX_FILES}"
|
||||
fi
|
||||
|
||||
if unzip -l "$ARCHIVE_PATH" 2>/dev/null | awk 'NR>3 {print $NF}' | grep -qE '(^/|(^|/)\.\.(/|$))'; then
|
||||
fn-archive-log-security-event "rejected_unsafe_zip_path" "zip" "$ARCHIVE_PATH" "absolute or traversal path detected"
|
||||
dokku_log_fail "Archive contains entries with unsafe paths"
|
||||
fi
|
||||
|
||||
fn-archive-log-security-event "extraction_started" "zip" "$ARCHIVE_PATH" "dest=${DEST_DIR}"
|
||||
unzip -d "$DEST_DIR" "$ARCHIVE_PATH"
|
||||
fn-archive-validate-extracted-symlinks "$DEST_DIR"
|
||||
fn-archive-log-security-event "extraction_completed" "zip" "$ARCHIVE_PATH" "dest=${DEST_DIR}"
|
||||
}
|
||||
@@ -2,6 +2,10 @@
|
||||
set -eo pipefail
|
||||
[[ $DOKKU_TRACE ]] && set -x
|
||||
|
||||
if [[ -f "${PLUGIN_CORE_AVAILABLE_PATH:-/var/lib/dokku/core-plugins/available}/common/archive-functions" ]]; then
|
||||
source "${PLUGIN_CORE_AVAILABLE_PATH:-/var/lib/dokku/core-plugins/available}/common/archive-functions"
|
||||
fi
|
||||
|
||||
has_tty() {
|
||||
declare desc="return 0 if we have a tty"
|
||||
if [[ "$DOKKU_FORCE_TTY" == "true" ]]; then
|
||||
|
||||
@@ -26,13 +26,13 @@ trigger-git-git-from-archive() {
|
||||
local COMMON_PREFIX=$(tar -tf "$TMP_WORK_DIR_2/src.tar" | sed -e 'N;s/^\(.*\).*\n\1.*$/\1\n\1/;D')
|
||||
local BOGUS_PARTS=$(echo "$COMMON_PREFIX " | awk 'BEGIN{FS="/"} {print NF-1}')
|
||||
dokku_log_verbose "Striping $BOGUS_PARTS worth of directories from tarball"
|
||||
tar -x -C "$TMP_WORK_DIR_3" -f "$TMP_WORK_DIR_2/src.tar" --strip-components="$BOGUS_PARTS"
|
||||
fn-archive-extract-tar "$TMP_WORK_DIR_2/src.tar" "$TMP_WORK_DIR_3" "tar" "$BOGUS_PARTS"
|
||||
elif [[ "$ARCHIVE_TYPE" == "tar.gz" ]]; then
|
||||
dokku_log_verbose "Extracting gzipped tarball"
|
||||
tar -x -C "$TMP_WORK_DIR_3" -f "$TMP_WORK_DIR_2/src.tar.gz" -z
|
||||
fn-archive-extract-tar "$TMP_WORK_DIR_2/src.tar.gz" "$TMP_WORK_DIR_3" "tar.gz" 0
|
||||
elif [[ "$ARCHIVE_TYPE" == "zip" ]]; then
|
||||
dokku_log_verbose "Extracting zipball"
|
||||
unzip -d "$TMP_WORK_DIR_3" "$TMP_WORK_DIR_2/src.zip"
|
||||
fn-archive-extract-zip "$TMP_WORK_DIR_2/src.zip" "$TMP_WORK_DIR_3"
|
||||
fi
|
||||
|
||||
chmod -R u+r "$TMP_WORK_DIR_3"
|
||||
|
||||
Reference in New Issue
Block a user