jailsetup.sh

   1 #!/bin/sh
   2 # The Girocco jail setup script
   3 #
   4 # We are designed to set up the chroot based on binaries from
   5 # amd64 Debian lenny; some things may need slight modifications if
   6 # being run on a different distribution.
   7
   8 set -e
   9
  10 . shlib.sh
  11
  12 # Verify we have all we neeed.
  13 if ! getent group $cfg_owning_group >/dev/null; then
  14         echo "*** Error: You do not have $cfg_owning_group in system yet." >&2
  15         exit 1
  16 fi
  17
  18 umask 022
  19 mkdir -p "$cfg_chroot"
  20 cd "$cfg_chroot"
  21 chown root "$cfg_chroot"
  22 chmod 755 "$cfg_chroot"
  23
  24 # First, setup basic directory structure
  25 mkdir -p bin dev etc lib sbin srv/git var/run proc
  26 rm -f usr lib64
  27 ln -s . usr
  28 ln -s lib lib64
  29
  30 # Set up basic user/group configuration; if there is any already,
  31 # we hope it's the same numbers and users.
  32
  33 if [ ! -s etc/passwd ]; then
  34         cat >etc/passwd <<EOT
  35 sshd:x:101:65534:priviledge separation:/var/run/sshd:/bin/false
  36 mob::65538:65534:the mob:/:/bin/git-shell
  37 EOT
  38 fi
  39
  40 if [ ! -s etc/group ]; then
  41         cat >etc/group <<EOT
  42 _repo:x:$(getent group "$cfg_owning_group" | cut -d : -f 3):
  43 sshd:x:101:65534:priviledge separation:/var/run/sshd:/bin/false
  44 mob::65538:65534:the mob:/:/bin/git-shell
  45 EOT
  46 fi
  47
  48 # Seed up /dev:
  49 rm -f dev/null dev/zero dev/random dev/urandom
  50 mknod dev/null c 1 3
  51 mknod dev/zero c 1 5
  52 mknod dev/random c 1 8
  53 mknod dev/urandom c 1 9
  54 chmod a+rw dev/null dev/zero dev/random dev/urandom
  55
  56 # Set up mob user:
  57 touch var/run/mob
  58 chown 65538 var/run/mob
  59 chmod 0 var/run/mob
  60
  61 # Set up sshd configuration:
  62 mkdir -p var/run/sshd
  63 mkdir -p etc/sshkeys
  64 chgrp $cfg_owning_group etc/sshkeys
  65 chmod g+ws etc/sshkeys
  66 mkdir -p etc/ssh
  67 if [ ! -s etc/ssh/sshd_config ]; then
  68         cat >etc/ssh/sshd_config <<EOT
  69 Protocol        2
  70 Port            22
  71 UsePAM          no
  72 X11Forwarding   no
  73 PermitRootLogin no
  74 UsePrivilegeSeparation yes
  75
  76 AuthorizedKeysFile      /etc/sshkeys/%u
  77 StrictModes     no
  78
  79 # mob user:
  80 PermitEmptyPasswords    yes
  81 ChallengeResponseAuthentication no
  82 PasswordAuthentication  yes
  83 EOT
  84 fi
  85 if [ ! -s etc/ssh/ssh_host_dsa_key ]; then
  86         yes | ssh-keygen -N "" -C Girocco -t dsa -f etc/ssh/ssh_host_dsa_key
  87         yes | ssh-keygen -N "" -C Girocco -t rsa -f etc/ssh/ssh_host_rsa_key
  88 fi
  89
  90 # Bring in basic libraries:
  91 rm -f lib/*
  92 # ld.so:
  93 cp -t lib /lib/ld-linux.so.2 /lib64/ld-linux-x86-64.so.2
  94 # libc:
  95 cp -t lib /lib/libc.so.6 /lib/libcrypt.so.1 /lib/libutil.so.1 /lib/libnsl.so.1 /lib/libnss_compat.so.2 /lib/libresolv.so.2 /lib/libdl.so.2 /lib/libgcc_s.so.1
  96
  97 # Now, bring in sshd and sh.
  98
  99 pull_in_bin() {
 100         bin="$1"; dst="$2"
 101         cp -t "$dst" "$bin"
 102         # ...and all the dependencies.
 103         ldd "$bin" | grep -v linux-vdso | grep -v ld-linux | grep '=>' | awk '{print $3}' | xargs -r -- cp -u -t lib
 104 }
 105
 106 pull_in_bin /bin/sh bin
 107 pull_in_bin /bin/nc.openbsd bin
 108 # If /sbin/sshd is already running within the chroot, we get Text file busy.
 109 pull_in_bin /usr/sbin/sshd sbin || :
 110
 111 # ...and the bits of git we need.
 112 for i in git git-index-pack git-receive-pack git-shell git-update-server-info git-upload-archive git-upload-pack git-unpack-objects; do
 113         pull_in_bin /usr/bin/$i bin
 114 done
 115
 116 echo "--- Add to your boot scripts: mount --bind $cfg_reporoot $cfg_chroot/srv/git"
 117 echo "--- Add to your boot scripts: mount --bind /proc $cfg_chroot/proc"
 118 echo "--- Add to your syslog configuration: listening on socket $cfg_chroot/dev/log"