t[cleanup] Introduce _whoami ; clean ; pass all tests with or without sudo - tomb - the crypto undertaker
HTML git clone git://parazyd.org/tomb.git
DIR Log
DIR Files
DIR Refs
DIR README
DIR LICENSE
---
DIR commit cd1ceac92e0a3ec32922f676b9c2ab245235cf1d
DIR parent b0538983000b6c6f23fee119a0b900a4a7a7746c
HTML Author: hellekin <hellekin@cepheide.org>
Date: Thu, 23 Oct 2014 22:48:05 -0300
t[cleanup] Introduce _whoami ; clean ; pass all tests with or without sudo
Diffstat:
M tomb | 320 ++++++++++++++++++++-----------
1 file changed, 210 insertions(+), 110 deletions(-)
---
DIR diff --git a/tomb b/tomb
t@@ -37,9 +37,15 @@
# {{{ Global variables
-VERSION=1.6
-DATE="Sept/2014"
-TOMBEXEC=$0
+typeset -r VERSION="1.7"
+typeset -r DATE="Oct/2014"
+typeset -r TOMBEXEC=$0
+
+# Tomb is using some global variables set by the shell:
+# TMPPREFIX, UID, GID, PATH, TTY, USERNAME
+# You can grep 'global variable' to see where they are used.
+
+# Keep a reference of the original command line arguments
typeset -a OLDARGS
for arg in ${argv}; do OLDARGS+=($arg); done
t@@ -49,7 +55,7 @@ DD=(dd)
WIPE=(rm -f)
MKFS=(mkfs.ext3 -q -F -j -L)
-# Flag optional commands if available
+# Flag optional commands if available (see _ensure_dependencies())
typeset -i 2 KDF=1
typeset -i 2 STEGHIDE=1
typeset -i 2 RESIZER=1
t@@ -57,20 +63,18 @@ typeset -i 2 SWISH=1
typeset -i 2 QRENCODE=1
# Default mount options
-MOUNTOPTS="rw,noatime,nodev"
-
-# prefix for temporary files
-TMPPREFIX="/dev/shm/$RANDOM.$RANDOM."
+typeset MOUNTOPTS="rw,noatime,nodev"
# Makes glob matching case insensitive
unsetopt CASE_MATCH
-typeset -AH OPTS # Command line options (see main())
+typeset -AH OPTS # Command line options (see main())
-# Command context
-typeset -H _UID # Running user identifier
-typeset -H _GID # Running user group identifier
-typeset -H _TTY # Connected input terminal
+# Command context (see _whoami())
+typeset -H _USER # Running username
+typeset -Hi _UID # Running user identifier
+typeset -Hi _GID # Running user group identifier
+typeset -H _TTY # Connected input terminal
# Tomb context (see _plot())
typeset -H TOMBPATH # Full path to the tomb
t@@ -87,8 +91,8 @@ typeset -H TOMBPASSWORD # Raw tomb passphrase (see gen_key(), ask_key_p
typeset -aH TOMBTMPFILES # Keep track of temporary files
typeset -aH TOMBLOOPDEVS # Keep track of used loop devices
-# Make sure sbin is in PATH
-PATH+=:/sbin:/usr/sbin
+# Make sure sbin is in PATH (man zshparam)
+path+=( /sbin /usr/sbin )
# For gettext
export TEXTDOMAIN=tomb
t@@ -116,15 +120,18 @@ _endgame() {
TOMBSECRET="$rr"; unset TOMBSECRET
TOMBPASSWORD="$rr"; unset TOMBPASSWORD
+ # Clear temporary files
for f in $TOMBTMPFILES; do
${=WIPE} "$f"
done
unset TOMBTMPFILES
+ # Detach loop devices
for l in $TOMBLOOPDEVS; do
losetup -d "$l"
done
unset TOMBLOOPDEVS
+
}
# Trap functions for the _endgame event
t@@ -138,52 +145,111 @@ TRAPPIPE() { _endgame PIPE }
TRAPTERM() { _endgame TERM }
TRAPSTOP() { _endgame STOP }
-check_shm() {
- # TODO: configure which tmp dir to use from a cli flag
- SHMPREFIX=/dev/shm
+# Identify the running user
+# Set global variables _UID, _GID, _TTY, and _USER, either from the
+# command line, -U, -G, -T, respectively, or from the environment.
+# Also update USERNAME and HOME to maintain consistency.
+_whoami() {
+ # Set global variables
+ typeset -gi _GID _UID
+ typeset -g _TTY _USER
+
+ # Get GID from option -G or the environment
+ option_is_set -G \
+ && _GID=$(option_value -G) || _GID=$(id -g)
+
+ # Get UID from option -U or the environment
+ option_is_set -U \
+ && _UID=$(option_value -U) || _UID=$(id -u)
+
+ # Set username from UID or environment
+ [[ -n $SUDO_USER ]] && _USER=$SUDO_USER
+ [[ -z $_USER && -n $USERNAME ]] && _USER=$USERNAME
+ [[ -z $_USER ]] && _USER=$(id -u)
+# _verbose "Identified caller: ::1 username:: (::2 UID:::::3 GID::)" \
+# $_USER $_UID $_GID
+
+ # Update USERNAME accordingly if we can
+ [[ EUID == 0 && $_USER != $USERNAME ]] && {
+# _verbose "Updating USERNAME from '::1 USERNAME::' to '::2 _USER::')" \
+# $USERNAME $_USER
+ USERNAME=$_USER
+ }
+
+ # Force HOME to _USER's HOME if necessary
+ local home=$(awk -F: "/$_USER/ { print \$6 }" /etc/passwd 2>/dev/null)
+ [[ $home == $HOME ]] || {
+ _verbose "Updating HOME to match user's: ::1 home:: (was ::2 HOME::)" \
+ $home $HOME
+ HOME=$home }
+
+ # Get connecting TTY from option -T or the environment
+ option_is_set -T && _TTY=$(option_value -T)
+ [[ -z $_TTY ]] && {
+ _TTY=$TTY
+ _verbose "Identified caller from tty ::1 TTY::)" $_TTY }
+}
- [[ -k /dev/shm ]] || [[ -k /run/shm ]] && { SHMPREFIX=/run/shm } \
- || {
- # mount the tmpfs if the SO doesn't already
- mkdir /run/shm
- (( $? )) && _failure "Fatal error creating a directory for temporary files"
+# Ensure temporary files remain in RAM
+# Set global variable TMPPREFIX
+# TODO: configure which tmp dir to use from a cli flag
+_ensure_safe_memory check_shm() {
+ local shmprefix=""
- mount -t tmpfs tmpfs /run/shm \
- -o nosuid,noexec,nodev,mode=0600,uid=$_UID,gid=$_GID
- (( $? )) && _failure "Fatal error mounting tmpfs in /run/shm for temporary files"
+ # Set $shmprefix to something sensible
+ [[ -z $shmprefix && -k /dev/shm ]] \
+ && shmprefix=/dev/shm || shmprefix=/run/shm
- SHMPREFIX=/run/shm
+ _whoami # Set _UID, _GID, _TTY, _USER
+
+ # Mount the tmpfs if the OS doesn't already
+ [[ -k $shmprefix ]] || {
+ mkdir -p $shmprefix/$_UID || {
+ _failure "Fatal error creating a directory for temporary files" }
+
+ mount -t tmpfs tmpfs $shmprefix/$_UID \
+ -o nosuid,noexec,nodev,mode=0700,uid=$_UID,gid=$_GID
+ [[ $? == 0 ]] || {
+ _failure "Cannot mount tmpfs in ::1 shm path::" $shmprefix }
}
- # setup a special env var for zsh to create temp files that will
- # then be deleted at the exit of each function using them.
- TMPPREFIX="$SHMPREFIX/$RANDOM.$RANDOM."
+ # Ensure all temporary files go into a user-specific directory for
+ # additional safety
+ mkdir -m 0700 -p $shmprefix/$_UID || {
+ _failure "Fatal error creating a directory for temporary files" }
+
+ # Set a global environment variable to ensure zsh will use that
+ # directory in RAM to keep temporary files by setting an. They
+ # will be created on demand and deleted as soon as the function
+ # using them ends.
+ TMPPREFIX="$shmprefix/$_UID/$RANDOM$RANDOM."
+
return 0
}
# Define sepulture's plot (setup tomb-related arguments)
-# Synopsis: _plot "/path/to/the.tomb"
+# Synopsis: _plot /path/to/the.tomb
_plot() {
# We set global variables
typeset -g TOMBPATH TOMBDIR TOMBFILE TOMBNAME
TOMBPATH="$1"
- _verbose '_plot TOMBPATH = ::1 tomb path::' $TOMBPATH
+# _verbose '_plot TOMBPATH = ::1 tomb path::' $TOMBPATH
TOMBDIR=$(dirname $TOMBPATH)
- _verbose '_plot TOMBDIR = ::1 tomb dir::' $TOMBDIR
+# _verbose '_plot TOMBDIR = ::1 tomb dir::' $TOMBDIR
TOMBFILE=$(basename $TOMBPATH)
- _verbose '_plot TOMBFILE = ::1 tomb file::' $TOMBFILE
+# _verbose '_plot TOMBFILE = ::1 tomb file::' $TOMBFILE
# The tomb name is TOMBFILE without an extension.
# It can start with dots: ..foo.tomb -> ..foo
TOMBNAME="${TOMBFILE%\.[^\.]*}"
- _verbose '_plot TOMBNAME = ::1 tomb name::' $TOMBNAME
+# _verbose '_plot TOMBNAME = ::1 tomb name::' $TOMBNAME
# Normalize TOMBFILE name
TOMBFILE="${TOMBNAME}.tomb"
- _verbose '_plot TOMBFILE = ::1 tomb file:: (normalized)' $TOMBFILE
+# _verbose '_plot TOMBFILE = ::1 tomb file:: (normalized)' $TOMBFILE
# Normalize TOMBPATH
TOMBPATH="${TOMBDIR}/${TOMBFILE}"
t@@ -415,8 +481,9 @@ lo_preserve() {
# eventually used for debugging
dump_secrets() {
- _verbose "TOMBFILE: ::1 tomb file::" $TOMBPATH
- _verbose "TOMBFILE: ::1 tomb file::" $TOMBFILE
+ _verbose "TOMBPATH: ::1 tomb path::" $TOMBPATH
+ _verbose "TOMBNAME: ::1 tomb name::" $TOMBNAME
+
_verbose "TOMBKEY: ::1 key:: chars long" ${#TOMBKEY}
_verbose "TOMBKEYFILE: ::1 key file::" $TOMBKEYFILE
_verbose "TOMBSECRET: ::1 secret:: chars long" ${#TOMBSECRET}
t@@ -611,33 +678,47 @@ progress() {
}
-# Check what's installed
-check_bin() {
- # check for required programs
+# Check program dependencies
+#
+# Tomb depends on system utilities that must be present, and other
+# functionality that can be provided by various programs according to
+# what's available on the system. If some required commands are
+# missing, bail out.
+_ensure_dependencies check_bin() {
+
+ # The messages system requires gettext
+ command -v gettext >& - || {
+ echo "Missing required dependency: gettext. Please install it."
+ exit 1
+ }
+
+ # Check for required programs
for req in cryptsetup pinentry sudo gpg; do
- command -v $req >& - || exitv=1 _failure "Cannot find ::1::. It's a requirement to use Tomb, please install it." $req
+ command -v $req >& - || {
+ _failure "Missing required dependency ::1 command::. Please install it." $req }
done
- export PATH=/sbin:/usr/sbin:$PATH
+ # Ensure system binaries are available in the PATH
+ path+=(/sbin /usr/sbin) # zsh magic
- # which dd command to use
+ # Which dd command to use
command -v dcfldd >& - && DD=(dcfldd statusinterval=1)
- # which wipe command to use
+ # Which wipe command to use
command -v wipe >& - && WIPE=(wipe -f -s)
- # check for filesystem creation progs
+ # Check for filesystem creation programs
command -v mkfs.ext4 >& - && MKFS=(mkfs.ext4 -q -F -j -L)
- # check for steghide
+ # Check for steghide
command -v steghide >& - || STEGHIDE=0
- # check for resize
+ # Check for resize
command -v e2fsck resize2fs >& - || RESIZER=0
- # check for KDF auxiliary tools
+ # Check for KDF auxiliary tools
command -v tomb-kdb-pbkdf2 >& - || KDF=0
- # check for Swish-E file content indexer
+ # Check for Swish-E file content indexer
command -v swish-e >& - || SWISH=0
- # check for QREncode for paper backups of keys
+ # Check for QREncode for paper backups of keys
command -v qrencode >& - || QRENCODE=0
}
t@@ -1701,65 +1782,87 @@ mount_tomb() {
return 0
}
-# ## Hooks execution
+## HOOKS EXECUTION
+#
+# Execution of code inside a tomb may present a security risk, e.g.,
+# if the tomb is shared or compromised, an attacker could embed
+# malicious code. When in doubt, open the tomb with the -n switch in
+# order to skip this feature and verify the files mount-hooks and
+# bind-hooks inside the tomb yourself before letting them run.
+
+# Mount files and directories from the tomb to the current user's HOME.
+#
+# Synopsis: exec_safe_bind_hooks /path/to/mounted/tomb
+#
+# This can be a security risk if you share tombs with untrusted people.
+# In that case, use the -n switch to turn off this feature.
exec_safe_bind_hooks() {
- if [[ -n ${(k)OPTS[-o]} ]]; then
- MOUNTOPTS=${OPTS[-o]}
- fi
- local MOUNTPOINT="${1}"
- local ME=${SUDO_USER:-$(whoami)}
- local HOME=$(awk -v a="$ME" -F ':' '{if ($1 == a) print $6}' /etc/passwd 2>/dev/null)
- if [ $? -ne 0 ]; then
- _warning "How pitiful! A tomb, and no HOME."
- return 1
- fi
- if [ -z "$MOUNTPOINT" -o ! -d "$MOUNTPOINT" ]; then
- _warning "Cannot exec bind hooks without a mounted tomb."
- return 1
- fi
- if ! [ -r "$MOUNTPOINT/bind-hooks" ]; then
- _verbose "bind-hooks not found in ::1 mount point::" $MOUNTPOINT
- return 1
- fi
- typeset -al mounted
- typeset -Al maps
- maps=($(<"$MOUNTPOINT/bind-hooks"))
+ local mnt="$1" # First argument is the mount point of the tomb
+
+ # Default mount options are overridden with the -o switch
+ [[ -n ${(k)OPTS[-o]} ]] && MOUNTOPTS=${OPTS[-o]}
+
+ # No HOME set? Note: this should never happen again.
+ [[ -z $HOME ]] && {
+ _warning "How pitiful! A tomb, and no HOME."
+ return 1 }
+
+ [[ -z $mnt || ! -d $mnt ]] && {
+ _warning "Cannot exec bind hooks without a mounted tomb."
+ return 1 }
+
+ [[ ! -r "$mnt/bind-hooks" ]] && {
+ _verbose "bind-hooks not found in ::1 mount point::" $mnt
+ return 1 }
+
+ typeset -Al maps # Maps of files and directories to mount
+ typeset -al mounted # Track already mounted files and directories
+
+ maps=($(<"$mnt/bind-hooks"))
for dir in ${(k)maps}; do
- if [ "${dir[1]}" = "/" -o "${dir[1,2]}" = ".." ]; then
+ [[ "${dir[1]}" == "/" || "${dir[1,2]}" == ".." ]] && {
_warning "bind-hooks map format: local/to/tomb local/to/\$HOME"
- continue
- fi
- if [ "${${maps[$dir]}[1]}" = "/" -o "${${maps[$dir]}[1,2]}" = ".." ]; then
+ continue }
+
+ [[ "${${maps[$dir]}[1]}" == "/" || "${${maps[$dir]}[1,2]}" == ".." ]] && {
_warning "bind-hooks map format: local/to/tomb local/to/\$HOME. Rolling back"
for dir in ${mounted}; do umount $dir; done
- return 1
- fi
+ return 1 }
+
if [ ! -r "$HOME/${maps[$dir]}" ]; then
_warning "bind-hook target not existent, skipping ::1 home::/::2 subdir::" $HOME ${maps[$dir]}
- elif [ ! -r "$MOUNTPOINT/$dir" ]; then
- _warning "bind-hook source not found in tomb, skipping ::1 mount point::/::2 subdir::" $MOUNTPOINT $dir
+ elif [ ! -r "$mnt/$dir" ]; then
+ _warning "bind-hook source not found in tomb, skipping ::1 mount point::/::2 subdir::" $mnt $dir
else
- mount -o bind,$MOUNTOPTS $MOUNTPOINT/$dir $HOME/${maps[$dir]}
+ mount -o bind,$MOUNTOPTS $mnt/$dir $HOME/${maps[$dir]}
mounted+=("$HOME/${maps[$dir]}")
fi
done
}
-# Post mount hooks
+# Execute automated actions configured in the tomb.
+#
+# Synopsis: exec_safe_post_hooks /path/to/mounted/tomb [open|close]
+#
+# If an executable file named 'post-hooks' is found inside the tomb,
+# run it as a user. This might need a dialog for security on what is
+# being run, however we expect you know well what is inside your tomb.
+# If you're mounting an untrusted tomb, be safe and use the -n switch
+# to verify what it would run if you let it. This feature opens the
+# possibility to make encrypted executables.
exec_safe_post_hooks() {
- local mnt=$1 # first argument is where the tomb is mounted
- local ME=${SUDO_USER:-$(whoami)}
- if ! [ -x ${mnt}/post-hooks ]; then return; fi
- # if 'post-hooks' is found inside the tomb, check it: if it is an
- # executable, launch it as a user this might need a dialog for
- # security on what is being run, however we expect you know well
- # what is inside your tomb. this feature opens the possibility to
- # make encrypted executables.
- cat ${mnt}/post-hooks | head -n1 | grep '^#!/'
- if [ $? = 0 ]; then
- _success "Post hooks found, executing as user ::1 user name::." $SUDO_USER
- exec_as_user ${mnt}/post-hooks "$2" "$1"
- fi
+ local mnt=$1 # First argument is where the tomb is mounted
+ local act=$2 # Either 'open' or 'close'
+
+ # Only run if post-hooks has the executable bit set
+ [[ -x $mnt/post-hooks ]] || return
+
+ # If the file starts with a shebang, run it.
+ cat $mnt/post-hooks | head -n1 | grep '^#!\s*/' &> /dev/null
+ [[ $? == 0 ]] && {
+ _success "Post hooks found, executing as user ::1 user name::." $USERNAME
+ exec_as_user $mnt/post-hooks $act $mnt
+ }
}
# }}} - Tomb open
t@@ -2322,8 +2425,12 @@ slam_tomb() {
# }}} - Tomb close
# {{{ Main routine
+
main() {
+ _ensure_dependencies # Check dependencies are present or bail out
+ _ensure_safe_memory # Check available memory can be used safely
+
local -A subcommands_opts
### Options configuration
#
t@@ -2457,11 +2564,9 @@ main() {
done
fi
- # when we run as root, we remember the original uid:gid
- # to set permissions for the calling user and drop privileges
- if option_is_set -U; then _UID="`option_value -U`"; fi
- if option_is_set -G; then _GID="`option_value -G`"; fi
- if option_is_set -T; then _TTY="`option_value -T`"; fi
+ # When we run as root, we remember the original uid:gid to set
+ # permissions for the calling user and drop privileges
+ _whoami # Reset _UID, _GID, _TTY
[[ "$PARAM" == "" ]] && {
_verbose "Tomb command: ::1 subcommand::" $subcommand
t@@ -2469,8 +2574,9 @@ main() {
_verbose "Tomb command: ::1 subcommand:: ::2 param::" $subcommand $PARAM
}
- [[ $_UID == "" ]] || {
- _verbose "Caller: uid[::1 uid::], gid[::2 gid::], tty[::3 tty::]." $_UID $_GID $_TTY
+ [[ -z $_UID ]] || {
+ _verbose "Caller: uid[::1 uid::], gid[::2 gid::], tty[::3 tty::]." \
+ $_UID $_GID $_TTY
}
case "$subcommand" in
t@@ -2590,15 +2696,9 @@ EOF
# }}}
# {{{ Run
-check_bin
-check_shm
+main $@ || exit $? # Prevent `tomb source tomb` from exiting
-main $@
-ret=$?
-if [[ $ret != 0 ]]; then #this "if" seems useless, but avoid source tomb source from exiting
- exit $ret
-fi
# }}}
# -*- tab-width: 4; indent-tabs-mode:nil; -*-