First attempt.

1 files changed, 281 insertions, 0 deletions

diff --git a/letsencrypt b/letsencrypt
new file mode 100755
index 0000000..50406f7
--- /dev/null
+++ b/letsencrypt
@@ -0,0 +1,281 @@
+#!/bin/bash
+
+# Dependencies nc(1), openssl(1), socat(1)
+
+set -ue
+set -o pipefail
+PATH=/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+NAME=$(basename $0)
+
+WWW_USER=www-data
+WWW_GROUP=www-data
+ACME_WEBSERVER=acme-webserver
+ACME_CLIENT=acme-slave
+
+declare COMMAND ACCOUNTKEY
+declare -l GENKEY
+declare RUNAS QUIET= DEBUG=
+
+declare SRVCERT= CHAIN= CSR SRVKEY
+declare -l HASH=
+declare SUBJECT=/
+declare SAN=
+# https://security.stackexchange.com/questions/24106/which-key-usages-are-required-by-each-key-exchange-method
+declare KEYUSAGE='digitalSignature, keyEncipherment, keyCertSign'
+declare -a NOTIFY=()
+
+usage() {
+    local msg="${1:-}"
+    if [ "$msg" ]; then
+        echo "$NAME: $msg" >&2
+        echo "Try '$NAME --help' for more information." >&2
+        exit 1
+    fi
+    cat <<- EOF
+		Usage: $NAME [OPTIONS] new-reg ACCOUNTKEY [EMAIL ..]
+		  or: $NAME [OPTIONS] new-cert ACCOUNTKEY --output=CERT {--csr=CSR | CSR Options }
+		  or: $NAME [OPTIONS] revoke-cert ACCOUNTKEY CERT [CERT ..]
+
+		ACCOUNTKEY is the private key file of the user's account.  Generic options are:
+		    --genkey[=ALGO[:BITS]]  For 'new-*' commands, generate key pairs (with mode 0600) if they don't
+		                            exist already. (Default: "RSA".)  RSA is the only algorithm curently supported.
+		    --runas=USERNAME        Username to run the ACME client as. (This user doesn't need access to
+		                            any private key material.)
+		    --help, -?              Display this help text and exit
+		    --quiet, -q             Be quiet
+		    --debug                 Turn on debug mode
+
+		$NAME new-reg ACCOUNTKEY [EMAIL ..]
+		  Register a new ACCOUNTKEY; an optional list of EMAIL addresses can be supplied as contact information.
+
+		$NAME new-cert ACCOUNTKEY --output=CERT --csr=FILE
+		$NAME new-cert ACCOUNTKEY --output=CERT --key=FILE [--hash=ALGO] [--subject=STRING] [--san=STRING] [--keyusage=STRING]
+		  Request a new Certificate Issuance.  The Certificate Signing Request can be supplied directly, or
+		  generated from the server key.
+
+		    --csr=FILE        Certificate Signing Request to send (alternatively, use --key to generate it)
+		    --key=FILE        Server private key (use --genkey to generate it)
+		    --hash=DGST       Message digest to sign the CSR with (in PEM format)
+		    --subject=STRING  Subject name, formatted as "/type0=value0/type1=value1/type2=..." (default: "/")
+		    --san=STRING      Comma-separated list of Subject Alternative Names formatted as "type:value"
+		    --keyusage=STRING Comma-separated list of Key Usages, see x509v3_config(5ssl)
+		                      (default: "digitalSignature,keyEncipherment,keyCertSign")
+		    --chain           Store not only the server certificate in the file specified with --output, but
+		                      also the CA's
+		    --output=FILE     Where to store the issued (signed) X.509 certificate
+		    --notify=COMMAND  Command to run upon success.  (This option can be repeated.)
+
+		$NAME revoke-cert {ACCOUNTKEY|SVRKEY} FILE [FILE ..]
+		  Request that the given certificate(s) FILE(s) be revoked.  The first argument can be either the account
+		  key file or the server's private key.
+	EOF
+    exit 0
+}
+
+# Generate a key pair with mode 0600
+genkey() {
+    local key="$1" genkey= bits=
+    case "$GENKEY" in
+        rsa) genkey=genrsa;;
+        rsa:*) genkey=genrsa; bits=${GENKEY#*:};;
+        *) echo "Error: invalid key type ${GENKEY%%:*}" >&2; exit 1;;
+    esac
+    install --mode=0600 /dev/null "$key" # atomic creation with mode 0600
+    openssl "$genkey" $bits >"$key"
+}
+
+
+# Parse options
+declare -a ARGV=()
+while [ $# -gt 0 ]; do
+    case "$1" in
+        --genkey) GENKEY=RSA;;
+        --genkey=*) GENKEY="${1#*=}";;
+        --runas=*) RUNAS="${1#*=}";;
+        --help|-\?) usage;;
+        --quiet|-q) QUIET=1;;
+        --debug) DEBUG=1;;
+
+        --output=*) SRVCERT="${1#*=}";;
+        --chain) CHAIN=1;;
+        --csr=*) CSR="${1#*=}";;
+        --key=*) SRVKEY="${1#*=}";;
+        --hash=*) HASH="${1#*=}";;
+        --subject=*) SUBJECT="${1#*=}";;
+        --san=*) SAN="${1#*=}";;
+        --keyusage=*) KEYUSAGE="${1#*=}";;
+        --notify=*) NOTIFY+=( "${1#*=}" );;
+
+        --) shift; ARGV+=( "$@" ); break ;;
+        -*) usage "unknown option '${1%%=*}'";;
+        *) if [ ${ACCOUNTKEY+x} ]; then
+               ARGV+=( "$1" )
+           else
+               [ ${COMMAND+x} ] && ACCOUNTKEY="$1" || COMMAND="$1"
+           fi
+    esac
+    shift
+done
+
+[ "${COMMAND:-}" ] || usage "missing command"
+[ "$COMMAND" = 'new-reg' -o "$COMMAND" = 'new-cert' -o "$COMMAND" = 'revoke-cert' ] ||
+    usage "invalid command $COMMAND"
+[ ${#ARGV[@]} -eq 0 -o "$COMMAND" = 'new-reg' -o "$COMMAND" = 'revoke-cert' ] ||
+    usage "invalid argument ${ARGV[0]}"
+
+[ "${ACCOUNTKEY:-}" ] || usage "missing account key"
+if ! [ -f "$ACCOUNTKEY" -a -s "$ACCOUNTKEY" ]; then
+    if [ "$COMMAND" = 'new-reg' -a "${GENKEY+x}" ]; then
+        genkey "$ACCOUNTKEY"
+    else
+        echo "Error: keyfile '$ACCOUNTKEY' does not exist." >&2
+        [[ ! "$COMMAND" =~ ^new- ]] || echo "Use 'new-reg --genkey' to generate and register an RSA key with mode 0600." >&2
+        exit 1
+    fi
+fi
+
+
+declare -a TMPFILES=()
+declare CHALLENGE_DIR IPTABLES_SAVE
+cleanup() {
+    set +e
+    [ ! ${IPTABLES_SAVE+x} ] || iptables-restore -c <"$IPTABLES_SAVE"
+    pkill -TERM -P $$
+    [ ${#TMPFILES[@]} -eq 0 ] || rm  -${DEBUG:+v}f "${TMPFILES[@]}"
+    [ ! ${CHALLENGE_DIR+x} ] || rm -${DEBUG:+v}rf "$CHALLENGE_DIR"
+}
+trap cleanup EXIT SIGINT
+
+
+# Extract the public part of the user key
+accountpub=$(mktemp --tmpdir XXXXXX.pub)
+TMPFILES+=( "$accountpub" )
+openssl pkey -pubout <"$ACCOUNTKEY" >"$accountpub"
+chmod 0644 "$accountpub"
+
+
+if [ "$COMMAND" = 'revoke-cert' ]; then
+    if [ ${#ARGV[@]} -eq 0 ]; then
+        echo "Error: Nothing to revoke" >&2
+        exit 1
+    fi
+elif [ "$COMMAND" = 'new-cert' ]; then
+    if [ ! "${SRVCERT:-}" ]; then
+        echo "Error: Missing --output" >&2
+        exit 1
+    fi
+
+    # Generate a Certificate Signing Request if need be
+    if [ ${CSR+x} ]; then
+        if [ -z "$CSR" -o ! -s "$CSR" ]; then
+            echo "Error: Missing Certificate Signing Request $CSR.  (One of --csr or --key must be set.)" >&2
+            exit 1
+        fi
+    else
+        CSR=$(mktemp --tmpdir XXXXXX.csr)
+        config=$(mktemp --tmpdir XXXXXX.cnf)
+        TMPFILES+=( "$CSR" "$config" )
+        chmod 0644 "$CSR"
+
+        if [ "$HASH" ]; then
+            case "$HASH" in
+                md5|rmd160|sha1|sha224|sha256|sha384|sha512) HASH="-$HASH";;
+                *) echo "Invalid digest algorithm: $HASH" >&2; exit 1;;
+            esac
+        fi
+        if [ ! "${SRVKEY:-}" ] || [ ! -s "$SRVKEY" ]; then
+            if [ "${SRVKEY:-}" -a "${GENKEY+x}" ]; then
+                genkey "$SRVKEY"
+            else
+                echo "Error: Missing private server key.  Use new-cert --genkey --key=... to generate" >&2
+                exit 1
+            fi
+        fi
+
+        [ ! "$DEBUG" ] || echo 'Generating Certificate Signing Request...' >&2
+        cat >"$config" <<- EOF
+			[ req ]
+			distinguished_name = req_distinguished_name
+			req_extensions     = v3_req
+
+			[ req_distinguished_name ]
+
+			[ v3_req ]
+			${SAN:+subjectAltName= $SAN}
+			# XXX Golang errors on extensions marked critical
+			# https://github.com/letsencrypt/boulder/issues/565
+			#basicConstraints     = critical, CA:FALSE
+			#keyUsage             = critical${KEYUSAGE:+, $KEYUSAGE}
+			basicConstraints     = CA:FALSE
+			keyUsage             = $KEYUSAGE
+			subjectKeyIdentifier = hash
+		EOF
+        openssl req -new -batch -key "$SRVKEY" $HASH -subj "$SUBJECT" -config "$config" -reqexts v3_req >"$CSR"
+    fi
+    [ ! "$DEBUG" ] || openssl req -noout -text <"$CSR"
+
+    CHALLENGE_DIR=$(mktemp --tmpdir -d acme-challenge.XXXXXX)
+    x509=$(mktemp --tmpdir XXXXXX.pem)
+    TMPFILES+=( "$x509" )
+
+    [ ! "${RUNAS:-}" ] || chown "$RUNAS" "$CHALLENGE_DIR" "$x509"
+    chgrp "$WWW_GROUP" "$CHALLENGE_DIR"
+    chmod 0750 "$CHALLENGE_DIR"
+
+    # Make sure a webserver is configured to server ACME challenges
+    if nc -z 127.0.0.1 80; then
+        [ ! "$DEBUG" ] || echo "Using existing webserver" >&2
+        ln -${DEBUG:+v}Ts "$CHALLENGE_DIR" /var/www/acme-challenge
+        TMPFILES+=( "/var/www/acme-challenge" )
+    else
+        temp=$(mktemp --tmpdir)
+        TMPFILES+=( "$temp" )
+        iptables-save -c >"$temp"
+        IPTABLES_SAVE="$temp"
+        iptables -I INPUT  -p tcp -m tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
+        iptables -I OUTPUT -p tcp -m tcp --sport 80 -m state --state     ESTABLISHED -j ACCEPT
+        (
+            [ ! "$DEBUG" ] || echo "Starting ACME webserver in $CHALLENGE_DIR" >&2
+            cd "$CHALLENGE_DIR" || exit 1
+            exec socat \
+                TCP-LISTEN:80,setgid="$WWW_GROUP",setuid="$WWW_USER",reuseaddr,fork,max-children=5 \
+                EXEC:"$ACME_WEBSERVER"
+        )&
+    fi
+
+    ARGV=( "$CSR" "$CHALLENGE_DIR" "$x509" )
+fi
+
+
+pipe=$(mktemp --tmpdir -u XXXXXX.fifo)
+mkfifo -m0600 "$pipe"
+TMPFILES+=( "$pipe" )
+
+# Wait for signing requests from the ACME slave
+acme_client() {
+    if [ "${RUNAS:-}" ]; then
+         sudo -u "$RUNAS" ${DEBUG:+DEBUG="$DEBUG"} -- $ACME_CLIENT "$@"
+    else
+        [ ${RUNAS+x} ] || echo "WARNING: Use --runas=USER to specify a user to drop permissions to." >&2
+        DEBUG="$DEBUG" $ACME_CLIENT "$@"
+    fi
+}
+
+acme_client "$COMMAND" "$accountpub" ${ARGV[0]+"${ARGV[@]}"} <"$pipe" |
+while read data; do
+    echo -n "$data" | openssl dgst -sha256 -sign "$ACCOUNTKEY" -hex | sed 's/.*=\s*//'
+done >"$pipe"
+
+if [ "$COMMAND" = 'new-cert' ]; then
+    # TODO
+    # Verify: dump and compare public keys
+    # Valid cert, signed by the right CA
+
+    # Copy "$x509" to "$SRVCERT", possibly chained
+    # https://crt.sh/?q=cse-fresti.cse.chalmers.se&iCAID=7395
+    cp "$x509" "$SRVCERT"
+
+    for (( i=0; i<${#NOTIFY[@]}; i++ )); do
+        ${NOTIFY[$i]}
+    done
+fi