bugfix: do not guess known IBANs

[confetti] / cgilite / session.sh

diff --git a/cgilite/session.sh b/cgilite/session.sh
index 93cc2f4e93f88c46f3d4dfea29b79ef402b8cf09..c3a44e80b335cc21ef36f23b7761065b883724b2 100755 (executable)
--- a/cgilite/session.sh
+++ b/cgilite/session.sh
@@ -1,11 +1,47 @@
 #!/bin/sh
 
+# Copyright 2018 - 2022 Paul Hänsch
+# 
+# Permission to use, copy, modify, and/or distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+# 
+# THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+# SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+# IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
 [ -n "$include_session" ] && return 0
 include_session="$0"
 
-_DATE="$(date +%s)"
+export _DATE="$(date +%s)"
 SESSION_TIMEOUT="${SESSION_TIMEOUT:-7200}"
 
+if ! which uuencode >/dev/null; then
+  uuencode() { busybox uuencode "$@"; }
+fi
+if ! which sha256sum >/dev/null; then
+  sha256sum() { busybox sha256sum "$@"; }
+fi
+
+if which openssl >/dev/null; then
+  session_mac(){ { [ $# -gt 0 ] && printf %s "$*" || cat; } | openssl dgst -sha1 -hmac "$(server_key)" -binary |slopecode; }
+else
+  # Gonzo MAC if openssl is unavailable
+  session_mac(){
+    { server_key | dd status=none bs=256 count=1 skip=1
+      { server_key | dd status=none bs=256 count=1
+        [ $# -gt 0 ] && printf %s "$*" || cat
+      } \
+      | sha256sum -;
+    } \
+    | sha256sum | cut -d\  -f1
+  }
+fi
+
 server_key(){
   IDFILE="${IDFILE:-${_DATA:-.}/serverkey}"
   if [ "$(stat -c %s "$IDFILE")" -ne 512 ] || ! cat "$IDFILE"; then
@@ -18,23 +54,13 @@ slopecode(){
   # 6-Bit Code that retains sort order of input data, while beeing safe to use
   # in ascii transmissions, unix file names, HTTP URLs, and HTML attributes
 
-  uuencode -m - | sed '
+  { [ $# -gt 0 ] && printf %s "$*" || cat; } \
+  | uuencode -m - | sed '
     1d;$d; 
     y;ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/;0123456789:=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz;
   '
 }
 
-session_mac(){
-  local info
-  [ $# -eq 0 ] && info="$(cat)" || info="$*"
-
-  if which openssl >/dev/null; then
-    printf %s "$info" |openssl dgst -sha1 -hmac "$(server_key)" -binary |slopecode
-  else
-    { printf %s "$info"; server_key; } |sha256sum |cut -d\  -f1
-  fi
-}
-
 randomid(){
   dd bs=12 count=1 if=/dev/urandom 2>&- \
   | slopecode
@@ -53,16 +79,17 @@ timeid(){
   } | slopecode
 }
 
-checkid(){ grep -m 1 -xE '[0-9a-zA-Z:=]{16}'; }
-
 transid(){
   # transaction ID to modify a given file
   local file="$1"
   session_mac "$(stat -c %F%i%n%N%s%Y "$file" 2>&-)" "$SESSION_ID"
 }
 
+checkid(){ { [ $# -gt 0 ] && printf %s "$*" || cat; } | grep -m 1 -xE '[0-9a-zA-Z:=]{16}'; }
+
 update_session(){
   local session sid time sig checksig
+  unset SESSION_KEY SESSION_ID
 
   read -r sid time sig <<-END
        $(POST session_key || COOKIE session)
@@ -70,19 +97,56 @@ update_session(){
   
   checksig="$(session_mac "$sid" "$time")"
   
-  if ! [ "$checksig" = "$sig" \
-    -a "$time" -ge "$_DATE" \
-    -a "$(printf %s "$sid" |checkid)" ] 2>&-
+  if [ "$checksig" = "$sig" \
+       -a "$time" -ge "$_DATE" \
+       -a "$(checkid "$sid")" ] 2>&-
   then
-    debug "Setting up new session"
-    sid="$(randomid)"
+    time=$(( $_DATE + $SESSION_TIMEOUT ))
+    sig="$(session_mac "$sid" "$time")"
+
+    SESSION_KEY="${sid} ${time} ${sig}"
+    SESSION_ID="${sid}"
+    return 0
+  else
+    return 1
   fi
 
+}
+
+new_session(){
+  local sid time sig
+
+  debug "Setting up new session"
+  sid="$(randomid)"
   time=$(( $_DATE + $SESSION_TIMEOUT ))
   sig="$(session_mac "$sid" "$time")"
-  printf %s\\n "${sid} ${time} ${sig}"
+
+  SESSION_KEY="${sid} ${time} ${sig}"
+  SESSION_ID="${sid}"
+}
+
+SESSION_BIND() {
+  # Set tamper-proof authenticated cookie
+  local key="$1" value="$2"
+  SET_COOKIE session "$key"="${value} $(session_mac "$value" "$SESSION_ID")" Path="/${_BASE#/}" SameSite=Strict HttpOnly
+}
+
+SESSION_VAR() {
+  # read authenticated cookie
+  # fail if value has been tampered with
+  local key="$1" value sig
+  value="$(COOKIE "$key")"
+  sig="${value##* }" value="${value% *}"
+  if [ "$sig" = "$(session_mac "$value" "$SESSION_ID")" ]; then
+    printf %s\\n "$value"
+  else
+    return 1
+  fi
+}
+
+SESSION_COOKIE() {
+  [ "$1" = new ] && new_session
+  SET_COOKIE 0 session="$SESSION_KEY" Path="/${_BASE#/}" SameSite=Strict HttpOnly
 }
 
-SESSION_KEY="$(update_session)"
-SET_COOKIE 0 session="$SESSION_KEY" Path=/ SameSite=Strict HttpOnly
-SESSION_ID="${SESSION_KEY%% *}"
+update_session || new_session